Diagnostic Imaging: Gastrointestinal [3 ed.]

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Michael P. Federle, MD Professor and Associate Chair for Education Department of Radiology Stanford University Medical Center Stanford, California

Siva P. Raman, MD Assistant Professor of Radiology Johns Hopkins University School of Medicine Baltimore, Maryland

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1600 John F. Kennedy Blvd. Ste 1800 Philadelphia, PA 19103-2899

DIAGNOSTIC IMAGING: GASTROINTESTINAL, THIRD EDITION

ISBN: 978-0-323-37755-3

Copyright © 2015 by Elsevier. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

Publisher Cataloging-in-Publication Data Diagnostic imaging. Gastrointestinal / [edited by] Michael P. Federle and Siva P. Raman. 3rd edition. pages ; cm Gastrointestinal Includes bibliographical references and index. ISBN 978-0-323-37755-3 (hardback) 1. Digestive organs--Imaging--Handbooks, manuals, etc. 2. Diagnostic imaging. I. Federle, Michael P. II. Raman, Siva P. III. Title: Gastrointestinal. [DNLM: 1. Radiography, Abdominal--methods.--Handbooks. 2. Digestive System Diseases--radiography--Handbooks. 3. Diagnostic Imaging--Handbooks. WI 900] RC944.D526 2015 617.5/507543--dc23 International Standard Book Number: 978-0-323-37755-3 Cover Designer: Tom M. Olson, BA Cover Art: Lane R. Bennion, MS Printed in Canada by Friesens, Altona, Manitoba, Canada Last digit is the print number: 9 8 7 6 5 4 3 2 1

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Dedications This book is dedicated to the phenomenal referring physicians at Stanford and Johns Hopkins Medical Centers who attract and care for some of the most challenging and LQWHUHVWLQJSDWLHQWVRIWHQUHIHUUHGVSHFLƬFDOO\WRWKHP because of their well-earned reputations for excellence. They keep us “on our toes,” and the most rewarding part of our jobs is to participate with them in advancing the evaluation and care of patients with abdominal disease and disorders. MPF

To my loving wife, Janani Venkateswaran, for her boundless understanding and patience. To my parents, Raghu and Visali, for their support throughout my entire career and education. To all my colleagues at Johns Hopkins. SPR

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Contributing Authors

Amir A. Borhani, MD Assistant Professor of Radiology University of Pittsburgh School of Medicine Pittsburgh, Pennsylvania

Mitchell Tublin, MD Professor and Vice Chairman Chief of Abdominal Imaging Department of Radiology University of Pittsburgh School of Medicine Pittsburgh, Pennsylvania

5%URRNH-HƪUH\0' Professor and Vice Chairman Department of Radiology Stanford University School of Medicine Stanford, California

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Preface

The second edition of Diagnostic Imaging: Abdomen was a major expansion of the ƬUVWHGLWLRQFRQWDLQLQJRYHUDGGLWLRQDO diagnoses. In planning this, the third edition, we soon realized that comprehensive coverage of all of the advances in imaging and management of abdominal disorders was no longer possible in a single volume text. Therefore, we elected to separate diagnoses judged primarily “gastrointestinal,” covered in this thoroughly updated text, from the “genitourinary” topics, to be covered in a subsequent book. We have maintained the classic Amirsys style of bulleted text, allowing us to present factual material in less than half the space with greater clarity and readability. We have, however, also maintained and expanded the popular Introduction and Overview sections, which are written in a more informal prose style, to help readers grasp the essential anatomical issues, imaging protocols, and general approaches to the most common DQGLPSRUWDQWGLVRUGHUVDƪHFWLQJWKDWRUJDQ system. As a new feature, we have added lists of WKHPRVWLPSRUWDQWGLƪHUHQWLDOGLDJQRVHV to each Introduction and Overview section, helping readers to zero in, for instance, on the possible etiologies for a “cystic SDQFUHDWLFPDVVq5HIHUHQFHWRVSHFLƬF chapters on the most likely candidates will then quickly lead to a more accurate and VSHFLƬFGLDJQRVLV

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Fluoroscopy in the modern era (read, CT, and endoscopy) has evolved to focus primarily on pre- and postoperative evaluation of patients for surgical alterations of the GI tract. Therefore, we have de-emphasized the more HVRWHULFDVSHFWVRIƮXRURVFRSLFGLDJQRVLVRI diseases in favor of more expansive coverage of the radiologist’s role in evaluating patients IRUEDULDWULFVXUJHU\DQWLUHƮX[SURFHGXUHV esophageal and bowel resections, and so forth. Additional detailed diagnostic material, images, and references are included in Elsevier’s Expert Consult, an eBook that accompanies the print version of Diagnostic Imaging: Gastrointestinal, Third Edition. We have updated and replaced most images from the second edition, maintaining only those judged to be so classic that newer examples would not be an improvement. All references and text have been updated as well, with all material being current to within a few months of the publication date of this book. The rapid preparation of this book was made possible in part by limiting the primary authorship to two experienced and highly motivated authors, who took responsibility for ZULWLQJDQGLOOXVWUDWLQJDOOSOXVFKDSWHUV We hope that this new edition of Diagnostic Imaging: Gastrointestinal will be a welcome addition to your library, but only after you have read it!

Michael P. Federle, MD Professor and Associate Chair for Education Department of Radiology Stanford University Medical Center Stanford, California

Siva P. Raman, MD Assistant Professor of Radiology Johns Hopkins University School of Medicine Baltimore, Maryland

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Acknowledgements Text Editing Dave L. Chance, MA, ELS Arthur G. Gelsinger, MA Nina I. Bennett, BA Sarah J. Connor, BA Tricia L. Cannon, BA Terry W. Ferrell, MS Lisa A. Gervais, BS

Image Editing -HƪUH\-0DUPRUVWRQH%6 Lisa A. M. Steadman, BS

Medical Editing Michael Sacerdote, MD

Illustrations Richard Coombs, MS Lane R. Bennion, MS Laura C. Sesto, MA

Art Direction and Design Tom M. Olson, BA Laura C. Sesto, MA

Lead Editor Sarah J. Connor, BA

Production Coordinators Angela M. Terry, BA Rebecca L. Hutchinson, BA

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Sections 6(&7,21$EGRPLQDO0DQLIHVWDWLRQVRI6\VWHPLF&RQGLWLRQV 6(&7,213HULWRQHXP0HVHQWHU\DQG$EGRPLQDO:DOO SECTION 3: Esophagus SECTION 4: Stomach SECTION 5: Duodenum SECTION 6: Small Intestine SECTION 7: Colon SECTION 8: Spleen SECTION 9: Liver 6(&7,21%LOLDU\6\VWHP SECTION 11: Pancreas xiii

TABLE OF CONTENTS

SECTION 1: ABDOMINAL MANIFESTATIONS OF SYSTEMIC CONDITIONS

58 62

INTRODUCTION AND OVERVIEW 4

Imaging Approach to Abdominal Manifestations of Systemic Conditions Michael P. Federle, MD

INFECTION 8 12 16

HIV/AIDS Siva Raman, MD Tuberculosis Siva Raman, MD Mononucleosis Siva Raman, MD

METABOLIC OR INHERITED 18 22 26 28

Cystic Fibrosis Siva Raman, MD Sickle Cell Anemia Siva Raman, MD Amyloidosis Siva Raman, MD Sarcoidosis Michael P. Federle, MD

SECTION 2: PERITONEUM, MESENTERY, AND ABDOMINAL WALL INTRODUCTION AND OVERVIEW 66

36 38

Systemic Hypotension Siva Raman, MD and Michael P. Federle, MD Superior Vena Cava Obstruction Siva Raman, MD Vasculitis Siva Raman, MD

TRAUMA 42 48

Foreign Bodies Siva Raman, MD Barotrauma Siva Raman, MD and Amir A. Borhani, MD

TRANSPLANTATION 50

Post-Transplant Lymphoproliferative Disorder Siva Raman, MD

MALIGNANT NEOPLASMS 54

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Leukemia and Lymphoma Siva Raman, MD

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall Michael P. Federle, MD

INFECTION 72

Abdominal Abscess Siva Raman, MD

INFLAMMATION 76 80

Peritonitis Siva Raman, MD Sclerosing Mesenteritis Siva Raman, MD

DEGENERATIVE 84 88

VASCULAR DISORDERS 34

Metastatic Melanoma Siva Raman, MD Kaposi Sarcoma Siva Raman, MD and Michael P. Federle, MD

Ascites Siva Raman, MD Omental Infarct Siva Raman, MD

EXTERNAL HERNIAS 92 96 98 100 101 102 103

Inguinal Hernia Siva Raman, MD Femoral Hernia Siva Raman, MD Obturator Hernia Siva Raman, MD and Michael P. Federle, MD Ventral Hernia Siva Raman, MD Spigelian Hernia Siva Raman, MD Lumbar Hernia Siva Raman, MD and Amir A. Borhani, MD Umbilical Hernia Siva Raman, MD and Amir A. Borhani, MD

INTERNAL HERNIAS 104

Paraduodenal Hernia Siva Raman, MD

TABLE OF CONTENTS 108 112 113

Transmesenteric Postoperative Hernia Siva Raman, MD Bochdalek Hernia Siva Raman, MD Morgagni Hernia Siva Raman, MD

VASCULAR DISORDERS 114

Portal Hypertension and Varices Siva Raman, MD

INFLAMMATION 166 170 172 174 175

TRAUMA 118 120

Traumatic Abdominal Wall Hernia Siva Raman, MD Traumatic Diaphragmatic Rupture Siva Raman, MD

TREATMENT RELATED 124 126 130

Postoperative State, Abdomen Siva Raman, MD Abdominal Incision and Injection Sites Siva Raman, MD Peritoneal Inclusion Cyst Siva Raman, MD

BENIGN NEOPLASMS 132 136

Lymphangioma (Mesenteric Cyst) Siva Raman, MD Desmoid Siva Raman, MD

176 177

DEGENERATIVE 178 179 180 184 188 192 194

MALIGNANT NEOPLASMS 140 144 148

Abdominal Mesothelioma Siva Raman, MD and Michael P. Federle, MD Peritoneal Metastases Siva Raman, MD Pseudomyxoma Peritonei Siva Raman, MD

MISCELLANEOUS 152 153

Eventration and Paralysis of the Diaphragm Siva Raman, MD Vicarious Excretion Siva Raman, MD and Michael P. Federle, MD

156

Imaging Approach to the Esophagus Michael P. Federle, MD

INFECTION 162 164 165

Candida Esophagitis Michael P. Federle, MD Viral Esophagitis Michael P. Federle, MD Chagas Disease Michael P. Federle, MD

Esophageal Webs Michael P. Federle, MD Cricopharyngeal Achalasia Michael P. Federle, MD Esophageal Achalasia Michael P. Federle, MD Esophageal Motility Disturbances Michael P. Federle, MD Esophageal Scleroderma Michael P. Federle, MD Schatzki Ring Michael P. Federle, MD Hiatal Hernia Michael P. Federle, MD

VASCULAR DISORDERS 198

Esophageal Varices Michael P. Federle, MD

ESOPHAGEAL DIVERTICULA 202 206 208 209

SECTION 3: ESOPHAGUS INTRODUCTION AND OVERVIEW

Reflux Esophagitis Michael P. Federle, MD Barrett Esophagus Michael P. Federle, MD Caustic Esophagitis Michael P. Federle, MD Drug-Induced Esophagitis Michael P. Federle, MD Radiation Esophagitis Michael P. Federle, MD Eosinophilic Gastroenteritis and Esophagitis Michael P. Federle, MD Epidermolysis and Pemphigoid Michael P. Federle, MD

Zenker Diverticulum Michael P. Federle, MD Intramural Pseudodiverticulosis Michael P. Federle, MD Traction Diverticulum Michael P. Federle, MD Pulsion Diverticulum Michael P. Federle, MD

TRAUMA 210 212 216

Esophageal Foreign Body Michael P. Federle, MD Esophageal Perforation Michael P. Federle, MD Boerhaave Syndrome Michael P. Federle, MD

TREATMENT RELATED 218

Esophagectomy: Ivor Lewis and Other Procedures Michael P. Federle, MD

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TABLE OF CONTENTS BENIGN NEOPLASMS 224 226 227

Intramural Benign Esophageal Tumors Michael P. Federle, MD Fibrovascular Polyp Michael P. Federle, MD Esophageal Inflammatory Polyp Michael P. Federle, MD and Amir A. Borhani, MD

MALIGNANT NEOPLASMS 228 232

Esophageal Carcinoma Michael P. Federle, MD Esophageal Metastases and Lymphoma Michael P. Federle, MD

SECTION 4: STOMACH INTRODUCTION AND OVERVIEW 236

Imaging Approach to the Stomach Michael P. Federle, MD

CONGENITAL 242

Gastric Diverticulum Michael P. Federle, MD

INFLAMMATION 244 248 252 256 258

Gastritis Michael P. Federle, MD Gastric Ulcer Michael P. Federle, MD Zollinger-Ellison Syndrome Michael P. Federle, MD Ménétrier Disease Michael P. Federle, MD Caustic Gastroduodenal Injury Michael P. Federle, MD

DEGENERATIVE 259 260 262

Gastroparesis Michael P. Federle, MD Gastric Bezoar Michael P. Federle, MD Gastric Volvulus Michael P. Federle, MD

TREATMENT RELATED 268 270 274 280

Iatrogenic Injury: Feeding Tubes Michael P. Federle, MD Partial Gastrectomy: Bilroth Procedures Michael P. Federle, MD Fundoplication Complications Michael P. Federle, MD Imaging of Bariatric Surgery Michael P. Federle, MD

BENIGN NEOPLASMS 286

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Gastric Polyps Michael P. Federle, MD

290

Intramural Benign Gastric Tumors Michael P. Federle, MD

MALIGNANT NEOPLASMS 294 298 304

Gastric GIST Michael P. Federle, MD and R. Brooke Jeffrey, MD Gastric Carcinoma Michael P. Federle, MD Gastric Metastases and Lymphoma Michael P. Federle, MD

SECTION 5: DUODENUM INTRODUCTION AND OVERVIEW 310

Imaging Approach to the Duodenum Michael P. Federle, MD

NORMAL VARIANTS AND ARTIFACTS 314

Duodenal Flexure Pseudotumor Michael P. Federle, MD

CONGENITAL 315

Duodenal Diverticulum Michael P. Federle, MD

INFLAMMATION 316 318 322

Duodenitis Michael P. Federle, MD Duodenal Ulcer Michael P. Federle, MD Brunner Gland Hyperplasia Michael P. Federle, MD and Amir A. Borhani, MD

VASCULAR DISORDERS 324

SMA Syndrome Michael P. Federle, MD and Amir A. Borhani, MD

TRAUMA 326

Gastroduodenal Trauma Michael P. Federle, MD

TREATMENT RELATED 328

Aortoenteric Fistula Michael P. Federle, MD and R. Brooke Jeffrey, MD

BENIGN NEOPLASMS 330

Duodenal Polyps Michael P. Federle, MD

MALIGNANT NEOPLASMS 334 338

Duodenal Carcinoma Michael P. Federle, MD Duodenal Metastases and Lymphoma Michael P. Federle, MD and R. Brooke Jeffrey, MD

TABLE OF CONTENTS SECTION 6: SMALL INTESTINE INTRODUCTION AND OVERVIEW 342

Imaging Approach to the Small Intestine Michael P. Federle, MD

CONGENITAL 348 350 351 352

Malrotation Michael P. Federle, MD Duplication Cyst Michael P. Federle, MD Small Bowel Diverticula Michael P. Federle, MD and R. Brooke Jeffrey, MD Meckel Diverticulum Michael P. Federle, MD

INFECTION 356 358 360

Mesenteric Adenitis and Enteritis Michael P. Federle, MD Intestinal Parasites and Infestation Michael P. Federle, MD Opportunistic Intestinal Infections Michael P. Federle, MD

INFLAMMATION 364 368 369 370 376 380 382

Celiac-Sprue Disease Michael P. Federle, MD Whipple Disease Siva Raman, MD Mastocytosis Michael P. Federle, MD Crohn Disease Michael P. Federle, MD Intestinal Scleroderma Michael P. Federle, MD Intestinal (Angioneurotic) Angioedema Michael P. Federle, MD and Amir A. Borhani, MD Small Bowel NSAID Stricture Michael P. Federle, MD

METABOLIC OR INHERITED 384

Intestinal Lymphangiectasia Michael P. Federle, MD

DEGENERATIVE 386 388 394 398 402 403

Ileus Michael P. Federle, MD and R. Brooke Jeffrey, MD Small Bowel Obstruction Michael P. Federle, MD Pneumatosis of the Intestine Michael P. Federle, MD Intussusception Michael P. Federle, MD Malabsorption Conditions Michael P. Federle, MD Gallstone Ileus Michael P. Federle, MD

404

Enteric Fistulas and Sinus Tracts Michael P. Federle, MD and Siva Raman, MD

VASCULAR DISORDERS 412

Ischemic Enteritis Michael P. Federle, MD

TRAUMA 416

Mesenteric and Small Bowel Trauma Michael P. Federle, MD

TREATMENT RELATED 422 426

Postoperative State, Bowel Michael P. Federle, MD Radiation Enteritis and Colitis Michael P. Federle, MD

TRANSPLANTATION 430

Small Intestine Transplantation Michael P. Federle, MD

BENIGN NEOPLASMS 434 435 436

Intramural (Mesenchymal) Intestinal Tumors Michael P. Federle, MD Ileocecal Valve Lipoma and Lipomatous Infiltration Michael P. Federle, MD Hamartomatous Polyposis Syndromes Michael P. Federle, MD

MALIGNANT NEOPLASMS 438 442 444 448

Carcinoid Tumor Michael P. Federle, MD Small Bowel Carcinoma Michael P. Federle, MD Intestinal Metastases and Lymphoma Michael P. Federle, MD Intestinal GIST Michael P. Federle, MD and Amir A. Borhani, MD

SECTION 7: COLON INTRODUCTION AND OVERVIEW 452

Imaging Approach to the Colon Michael P. Federle, MD

INFECTION 458 464

Infectious Colitis Michael P. Federle, MD Neutropenic Colitis (Typhlitis) Michael P. Federle, MD

INFLAMMATION AND ISCHEMIA 466 470

Ulcerative Colitis Michael P. Federle, MD Toxic Megacolon Michael P. Federle, MD

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TABLE OF CONTENTS 474 478 484 488 492 498

Ischemic Colitis Michael P. Federle, MD Appendicitis Michael P. Federle, MD Mucocele of the Appendix Michael P. Federle, MD Colonic Diverticulosis Michael P. Federle, MD Diverticulitis Michael P. Federle, MD Epiploic Appendagitis Michael P. Federle, MD

DEGENERATIVE 502 506 508 512 513

Sigmoid Volvulus Michael P. Federle, MD Cecal Volvulus Michael P. Federle, MD Colonic Ileus and Ogilvie Syndrome Michael P. Federle, MD Fecal Impaction and Stercoral Ulceration Michael P. Federle, MD Rectal Prolapse and Intussusception Michael P. Federle, MD

TRAUMA 514

Colorectal Trauma Michael P. Federle, MD

BENIGN NEOPLASMS 516 520

Colonic Polyps Siva Raman, MD Villous Adenoma Michael P. Federle, MD

MALIGNANT NEOPLASMS 524 530 534 540 541

Colon Carcinoma Michael P. Federle, MD Rectal Carcinoma Michael P. Federle, MD Familial Polyposis and Gardner Syndrome Michael P. Federle, MD Appendiceal Tumors Michael P. Federle, MD Colonic Metastases and Lymphoma Michael P. Federle, MD and R. Brooke Jeffrey, MD

SECTION 8: SPLEEN INTRODUCTION AND OVERVIEW 544

Imaging Approach to the Spleen Michael P. Federle, MD

NORMAL VARIANTS AND ARTIFACTS 548

Accessory Spleen Siva Raman, MD

CONGENITAL 550

INFECTION 554

Splenic Infection and Abscess Siva Raman, MD

DEGENERATIVE 558

Splenomegaly and Hypersplenism Siva Raman, MD

VASCULAR DISORDERS 562

Splenic Infarction Siva Raman, MD

TRAUMA 566 570

Splenic Trauma Siva Raman, MD and R. Brooke Jeffrey, MD Splenosis Siva Raman, MD

BENIGN NEOPLASMS 572 574

Splenic Cyst Siva Raman, MD Primary Splenic Tumors Siva Raman, MD

MALIGNANT NEOPLASMS 578

Splenic Metastases and Lymphoma Siva Raman, MD

SECTION 9: LIVER INTRODUCTION AND OVERVIEW 584

Imaging Approach to the Liver Michael P. Federle, MD

CONGENITAL 590 594 598

Congenital Hepatic Fibrosis Michael P. Federle, MD AD Polycystic Liver Disease Michael P. Federle, MD Congenital Absence of Hepatic Segments Michael P. Federle, MD

INFECTION 600 604 608 612 616

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Asplenia and Polysplenia Siva Raman, MD

Hepatic Pyogenic Abscess Michael P. Federle, MD Hepatic TB and Fungal Infections Michael P. Federle, MD Hepatic Amebic Abscess Michael P. Federle, MD Hepatic Hydatid Cyst Michael P. Federle, MD Hepatic Schistosomiasis Michael P. Federle, MD

TABLE OF CONTENTS 620

Viral Hepatitis Michael P. Federle, MD

INFLAMMATION 626 630 632 638 642 652 658 662 668 676 677

Alcoholic Liver Disease Michael P. Federle, MD Autoimmune Hepatitis Michael P. Federle, MD Steatosis and Steatohepatitis Michael P. Federle, MD Hepatic Injury From Toxins Michael P. Federle, MD Cirrhosis Michael P. Federle, MD Primary Biliary Cirrhosis Michael P. Federle, MD Focal Confluent Fibrosis Michael P. Federle, MD Nodular Regenerative Hyperplasia Michael P. Federle, MD Regenerative and Dysplastic Nodules Michael P. Federle, MD Solitary Necrotic Nodule Michael P. Federle, MD Peribiliary Cysts Michael P. Federle, MD

METABOLIC OR INHERITED 678 680 684

Glycogen Storage Disease Michael P. Federle, MD Hemochromatosis Michael P. Federle, MD Wilson Disease Michael P. Federle, MD

726 732

TRAUMA 736

Hepatomegaly Michael P. Federle, MD

VASCULAR DISORDERS 690

696 700 706 710 716 718 722

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs) Michael P. Federle, MD Arterioportal Shunt Michael P. Federle, MD Portal Vein Occlusion Michael P. Federle, MD Passive Hepatic Congestion Michael P. Federle, MD Budd-Chiari Syndrome Michael P. Federle, MD Venoocclusive Disease Michael P. Federle, MD Hepatic Infarction Michael P. Federle, MD Peliosis Hepatis Michael P. Federle, MD

Hepatic Trauma Michael P. Federle, MD

TREATMENT RELATED 740 744 748 754

Radiation-Induced Liver Disease Michael P. Federle, MD Postoperative Changes, Liver Michael P. Federle, MD Transjugular Intrahepatic Portosystemic Shunt (TIPS) Michael P. Federle, MD Hepatic Transplantation Michael P. Federle, MD

BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 764 772 780 786 794 798 802

DEGENERATIVE 688

Hereditary Hemorrhagic Telangiectasia Michael P. Federle, MD HELLP Syndrome Michael P. Federle, MD

Hepatic Cyst Michael P. Federle, MD Hepatic Cavernous Hemangioma Michael P. Federle, MD Focal Nodular Hyperplasia Michael P. Federle, MD Hepatic Adenoma Michael P. Federle, MD Biliary Hamartoma Michael P. Federle, MD Hepatic Angiomyolipoma and Lipoma Michael P. Federle, MD Hepatic Inflammatory Pseudotumor Michael P. Federle, MD

MALIGNANT NEOPLASMS 806 814 820 826 832 838 842 844

Hepatocellular Carcinoma Michael P. Federle, MD Fibrolamellar Carcinoma Michael P. Federle, MD Peripheral (Intrahepatic) Cholangiocarcinoma Michael P. Federle, MD Epithelioid Hemangioendothelioma Michael P. Federle, MD Biliary Cystadenocarcinoma Michael P. Federle, MD Hepatic Angiosarcoma Michael P. Federle, MD Undifferentiated Sarcoma Michael P. Federle, MD Hepatic Metastases and Lymphoma Michael P. Federle, MD

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TABLE OF CONTENTS SECTION 10: BILIARY SYSTEM INTRODUCTION AND OVERVIEW 854

Imaging Approach to the Biliary System Michael P. Federle, MD

NORMAL VARIANTS AND ARTIFACTS 862

Biliary Normal Variants and Artifacts Siva Raman, MD

CONGENITAL 866 870 874

Congenital Abnormalities of the Gallbladder Siva Raman, MD Caroli Disease Siva Raman, MD Choledochal Cyst Siva Raman, MD

INFECTION 878 882 886 890 892

Recurrent Pyogenic Cholangitis Siva Raman, MD Ascending Cholangitis Siva Raman, MD Pancreatobiliary Parasites Siva Raman, MD AIDS Cholangiopathy Siva Raman, MD Gallbladder Hydrops and Empyema Siva Raman, MD

VASCULAR DISORDERS 942

TRAUMA 946

902 906 910 914 918 922 926 928 930 934

Gallstones and Sludge Siva Raman, MD Acute Calculous Cholecystitis Siva Raman, MD Acalculous Cholecystitis Siva Raman, MD Xanthogranulomatous Cholecystitis Siva Raman, MD and Mitchell Tublin, MD Emphysematous Cholecystitis Siva Raman, MD Mirizzi Syndrome Siva Raman, MD Hyperplastic Cholecystoses Siva Raman, MD Porcelain Gallbladder Siva Raman, MD Milk of Calcium Bile Siva Raman, MD and Mitchell Tublin, MD Autoimmune (IgG4) Cholangitis Siva Raman, MD Primary Sclerosing Cholangitis Siva Raman, MD

DEGENERATIVE 938

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Biloma Siva Raman, MD

Biliary Trauma Siva Raman, MD

TREATMENT RELATED 950

Chemotherapy-Induced Cholangitis Siva Raman, MD and Mitchell Tublin, MD

BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 952

Gallbladder Polyps Siva Raman, MD and Mitchell Tublin, MD

MALIGNANT NEOPLASMS 956 960 964 965 966

Gallbladder Carcinoma Siva Raman, MD Ampullary Carcinoma Siva Raman, MD Biliary Metastases and Lymphoma Siva Raman, MD Biliary Papillomatosis Siva Raman, MD and Mitchell Tublin, MD Biliary IPMN Siva Raman, MD

SECTION 11: PANCREAS

INFLAMMATION 896

Ischemic Bile Duct Injury Siva Raman, MD

INTRODUCTION AND OVERVIEW 972

Imaging Approach to the Pancreas Michael P. Federle, MD

CONGENITAL 980 981 982 986 988

Agenesis of Dorsal Pancreas Siva Raman, MD Annular Pancreas Siva Raman, MD Pancreas Divisum Siva Raman, MD Asymmetric Fatty Lobulation of the Pancreas Siva Raman, MD Ectopic Pancreatic Tissue Siva Raman, MD

INFLAMMATION 990

Acute Pancreatitis and Complications Siva Raman, MD 1000 Chronic Pancreatitis Siva Raman, MD 1004 Groove Pancreatitis Siva Raman, MD 1008 Autoimmune (IgG4) Pancreatitis Siva Raman, MD

TABLE OF CONTENTS DEGENERATIVE 1012 Pancreatic Lipomatous Pseudohypertrophy Siva Raman, MD and Michael P. Federle, MD

TRAUMA 1014 Pancreatic Trauma Siva Raman, MD

TREATMENT RELATED 1018 Postoperative Pancreas Siva Raman, MD 1022 Pancreatic Transplantation Siva Raman, MD

BENIGN NEOPLASMS AND TUMOR-LIKE CONDITIONS 1026 Pancreatic Serous Cystadenoma Siva Raman, MD 1030 Nonneoplastic Pancreatic Cysts Siva Raman, MD

MALIGNANT NEOPLASMS 1034 Pancreatic Ductal Carcinoma Siva Raman, MD 1042 Mucinous Cystic Pancreatic Tumor Siva Raman, MD 1048 Pancreatic IPMN Siva Raman, MD 1054 Pancreatic Neuroendocrine Tumors Siva Raman, MD 1060 Pancreatic Solid and Pseudopapillary Neoplasm Siva Raman, MD 1064 Pancreatic Metastases and Lymphoma Siva Raman, MD 1068 Atypical and Rare Pancreatic Tumors Siva Raman, MD

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SECTION 1

Abdominal Manifestations of Systemic Conditions

Introduction and Overview Imaging Approach to Abdominal Manifestations of Systemic Conditions

4

Infection HIV/AIDS Tuberculosis Mononucleosis

8 12 16

Metabolic or Inherited Cystic Fibrosis Sickle Cell Anemia Amyloidosis Sarcoidosis

18 22 26 28

Vascular Disorders Systemic Hypotension Superior Vena Cava Obstruction Vasculitis

34 36 38

Trauma Foreign Bodies Barotrauma

42 48

Transplantation Post-Transplant Lymphoproliferative Disorder

50

Malignant Neoplasms Leukemia and Lymphoma Metastatic Melanoma Kaposi Sarcoma

54 58 62

Abdominal Manifestations of Systemic Conditions

Imaging Approach to Abdominal Manifestations of Systemic Conditions

Organizational Approach to Abdominal Diseases Most information about imaging abdominal disorders, including the gastrointestinal and genitourinary systems, fits neatly into an organ-by-organ framework. However, this approach makes it difficult to discuss diseases or conditions with manifestations throughout the abdomen and beyond. For this reason, some conditions are best discussed from a systemic perspective. Doing so provides a more accurate portrayal of these entities, and avoids unwanted redundancy. Because many systemic disorders affect lymph node groups, neural structures, or major vessels throughout the abdomen, medical illustrations provide a helpful reminder of important anatomical considerations. Systemic infections (including AIDS, tuberculosis, and mononucleosis) are discussed, along with important clues to help identify the infectious and neoplastic diseases they may cause or simulate. Degenerative conditions, such as sarcoidosis and vascular disorders, are rarely limited to a single organ. These are presented in all their guises, along with tips as to how to address differential diagnoses. Foreign bodies may be encountered throughout the gastrointestinal and genitourinary system and are well-known to be found repeatedly in certain individuals. Keys to recognition on imaging and avoiding common pitfalls are covered here. Many malignant neoplasms are, by their very nature, systemic processes, such as lymphoma, leukemia, and malignant melanoma. Therefore, taking a systemic approach to such diagnoses gives us the opportunity to bring together some general principles about the presentation, diagnosis, and management of these important diseases. Finally, while some conditions, such as systemic hypotension or hypervolemia, do not represent disease per se, they can result in important clinical and imaging abnormalities that must be recognized to avoid misguided patient management.

(Left) Coronal volumerendered CTA shows the entire common hepatic artery arising from the superior mesenteric artery. The left gastric artery also has a separate origin from the aorta, though difficult to perceive on this image. The "celiac trunk" in this patient consists only of the splenic artery. Congenital variations of vascular anatomy are very common. (Right) Oblique view of CTA clearly shows the origin of the accessory right hepatic artery from the superior mesenteric artery.

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Imaging Modalities Plain radiography maintains an important role for surveillance of some generalized disease processes, such as the osseous and visceral manifestations of sickle cell anemia or cystic fibrosis. Ultrasound is an important imaging tool for the evaluation of biliary, vascular, gynecologic, and scrotal pathology, but it lacks both sensitivity and specificity in evaluating other processes, especially bowel pathology. Computed tomography (CT) has become the essential tool for the comprehensive evaluation of most traumatic, inflammatory, and neoplastic abdominal processes. In patients with cancer, for instance, the ability to quickly and accurately examine different anatomic areas (thorax, abdomen, and pelvis), organs, and structures of different composition (e.g., lung, liver, and bone) is a tremendous advantage. Thus, there is continued growth and popularity of CT even in this era of powerful "competing" modalities, such as positron emission tomography (PET) and magnetic resonance (MR) imaging. PET and MR imaging do serve an important role as problemsolving tools for evaluating abdominal pathology. MR, with its excellent soft tissue characterization, is particularly helpful in evaluating masses within solid abdominal organs. Catheter angiography remains the most accurate means of identifying certain vascular disorders and often results in catheter-based therapies in the same setting. For vasculitides, which routinely affect vessels throughout the body, angiography maintains an essential diagnostic and therapeutic role.

Imaging Approach to Abdominal Manifestations of Systemic Conditions

Inferior vena cava (IVC) Adrenal veins

Renal veins Right gonadal vein

Ascending lumbar vein

Ascending lumbar vein

Abdominal Manifestations of Systemic Conditions

Inferior phrenic veins

Middle sacral vein External iliac vein Internal iliac (hypogastric) vein

Celiac nodes Thoracic duct Superior mesenteric nodes Cisterna chyli

Lumbar trunks (of cisterna chyli)

Intestinal trunk (of cisterna chyli)

Right lumbar (retrocaval) node

Lumbar (paraaortic) nodes

Aortocaval nodes

Inferior mesenteric nodes

Common iliac nodes External iliac node Internal iliac (hypogastric) nodes

(Top) The inferior vena cava (IVC) is formed by the confluence of the common iliac veins, which are formed by the confluence of the internal and external iliac veins. Note the ascending lumbar veins, which anastomose freely between the IVC and azygous, hemiazygos, and renal veins. These form a pathway for collateral flow in the event of IVC obstruction and play an important role in the systemic spread of pelvic tumors and infection. (Bottom) The major lymphatics and lymph nodes of the abdomen are located along, and share the same name as, the major blood vessels.

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Abdominal Manifestations of Systemic Conditions

Imaging Approach to Abdominal Manifestations of Systemic Conditions

(Left) Axial CT in a 50-year-old woman with non-Hodgkin lymphoma (NHL) shows splenomegaly and marked enlargement of multiple upper abdominal and retrocrural lymph nodes. (Right) On this CT section in the same case, the duodenum is displaced by large retroperitoneal nodes; the mesenteric vessels are surrounded or "sandwiched" by mesenteric nodes . The lumbar nodes are often referred to as para- or retroaortic (or -caval) , indicating their position relative to the great vessels.

(Left) This 33-year-old African American woman presented with dyspnea and general weakness. CT shows bilateral hilar and subcarinal lymphadenopathy . (Right) CT at lung windows in the same patient shows diffuse pulmonary nodules predominantly in a peribronchial distribution.

(Left) CT in the same patient shows massive splenomegaly with innumerable small, poorly defined, hypodense nodules. Similar lesions were present in the liver, better seen on narrow window-width images (not shown). There are innumerable focal hypodense nodules in both kidneys, as well as upper abdominal lymphadenopathy . (Right) CT in the same patient shows more of the splenic , renal , and nodal disease. All lesions were found to represent sarcoidosis and responded to steroid medication.

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Imaging Approach to Abdominal Manifestations of Systemic Conditions Abdominal Manifestations of Systemic Conditions

(Left) This woman had abdominal pain for several months following laparoscopic right nephrectomy. A digital radiograph shows a curvilinear radiopaque stripe within the right side of the abdomen . (Right) CT in the same patient shows an encapsulated collection of fluid and gas density with an adjacent thin, radiopaque structure that corresponds to the stripe seen on the radiograph. This is a classic gossypiboma, a retained surgical sponge that has resulted in a chronic abscess or foreign body reaction.

(Left) This young man was injured in a motor vehicle crash (MVC). CT shows a distended IVC and periportal edema , which might be mistaken for dilated bile ducts or hepatic injury. (Right) CT in the same patient shows water density ascites in the Morison pouch. There was no hemoperitoneum nor visceral injury. The findings were due to aggressive IV hydration of the patient and resolved by the following morning.

(Left) This young man was injured in an MVC. CT shows diffuse infiltration of the peripancreatic and mesenteric fat planes. The IVC and renal veins appear flattened . (Right) CT in the same patient shows the classic "shock bowel" appearance of intense mucosal enhancement and submucosal edema. All of these findings are explainable by severe hypotension alone. There was no abdominal visceral or bowel injury, and a repeat CT scan the next morning was completely normal.

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Abdominal Manifestations of Systemic Conditions

HIV/AIDS KEY FACTS

TERMINOLOGY • Abdominal opportunistic infections and neoplasms resulting from HIV/AIDS-related immunodeficiency

IMAGING • Liver and spleen ○ Small hypodense nodules may be microabscesses ○ Larger hypodense lesions might be infectious, but AIDSrelated lymphoma should be considered ○ Pneumocystis may result in tiny calcifications • Biliary tree ○ Cholangitis or acalculous cholecystitis caused by opportunistic infections • Stomach, small bowel, and large bowel ○ Wall thickening raises concern for opportunistic infection, which can involve any segment of GI tract ○ Mural thickening of esophagus suggests esophagitis, often due to candidiasis, CMV, or HSV

(Left) Coronal volumerendered CECT in an AIDS patient with low CD4 count demonstrates diffuse thickening of the small bowel with surrounding ascites. The bowel appeared similar on several subsequent studies, and this was found to be infection with MAI. (Right) Axial CECT in an HIV-positive patient presenting with 3 weeks of fever, diarrhea, and weight loss shows multiple sites of low-attenuation lymphadenopathy involving retroperitoneal and mesenteric nodes. Biopsy confirmed MAI.

(Left) Axial CECT shows innumerable small hypodense foci in the spleen and, more subtly, in the liver. Both the liver and spleen are enlarged. (Right) Axial CECT in the same patient demonstrates multiple low-density enlarged lymph nodes . This constellation of findings was found to represent disseminated mycobacterial infection.

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○ Proctitis in homosexual men related to sexual activity may be due to Neisseria gonorrhoeae, Chlamydia, or HSV ○ Focal mass-like wall thickening in GI tract should raise concern for malignancy (lymphoma, Kaposi sarcoma) • Lymph nodes ○ Mild generalized lymphadenopathy (usually < 1.5 cm) is typically reactive and may be 1st clue to HIV infection ○ More significant adenopathy (> 1.5 cm) suggests opportunistic infection or AIDS-related lymphoma • Kidney ○ Bilateral large kidneys ( echogenicity on US) with urothelial thickening due to HIV nephropathy

PATHOLOGY • Infections more common in HIV patients even with CD4 > 200, although risk substantially with lower CD4 counts • Incidence of AIDS-defining malignancies (AIDS-related nonHodgkin lymphoma, Kaposi sarcoma) has dramatically with antiretroviral therapy

HIV/AIDS

Abbreviations • Acquired immune deficiency syndrome (AIDS) • Human immunodeficiency virus (HIV)

Definitions • Abdominal opportunistic infections and neoplasms resulting from HIV/AIDS-related immunodeficiency

IMAGING General Features • Location ○ Can affect visceral organs, gastrointestinal tract, genitourinary tract, and lymph nodes • Size ○ Variable: Ranges from microabscesses (< 1 cm) to large masses due to lymphoma or Kaposi sarcoma

Imaging Recommendations • Best imaging tool ○ CECT

CT Findings • Liver ○ Liver may appear nodular and cirrhotic due to strong demographic overlap of HIV and chronic viral hepatitis ○ Small hypodense nodules scattered throughout liver suggests microabscesses (often due to Mycobacterium avium-intracellulare [MAI], tuberculosis, histoplasmosis, Candida, Pneumocystis, etc.) ○ Liver may appear globally enlarged without focal lesions due to infiltrative infections (e.g., MAI) ○ Pneumocystis (and rarely CMV or MAI) can result in multiple tiny calcifications throughout liver – Calcifications do not signify inactive disease ○ Liver involved in up to 1/4 of patients with AIDS-related lymphoma with hypodense nodules of variable size • Biliary tree ○ Cholangitis caused by opportunistic infections – Intrahepatic and extrahepatic biliary strictures with papillary stenosis: Bile ducts may appear thickened and enhancing – Bile ducts may have beaded appearance very similar to primary sclerosing cholangitis ○ Acalculous cholecystitis due to opportunistic infections (e.g., CMV, Cryptosporidium) – Thickened gallbladder with pericholecystic fluid and stranding • Spleen ○ Splenomegaly in up to 3/4 of AIDS patients without infection or tumor ○ Small tiny hypodense foci (microabscesses) usually due to disseminated infection (e.g., Candida, MAI, tuberculosis, coccidioidomycosis, Pneumocystis, etc.) ○ Larger hypodense lesions might still be infectious, but AIDS-related lymphoma should also be considered ○ Small calcifications (similar to liver) from Pneumocystis • Stomach, small bowel, and large bowel

○ Bowel wall thickening, mucosal hyperemia, and fat stranding surrounding bowel should always raise concern for infection (including opportunistic infections) – CMV-related ulcerations of bowel may lead to GI tract perforation (one of the most common reasons for emergent abdominal surgery in AIDS patients) ○ Most opportunistic infections can involve any segment of GI tract (Cryptosporidium, CMV, MAI, tuberculosis, microsporidium, Clostridium difficile, amebiasis, etc.) – Difficult to predict pathogen based on distribution, but some organisms have predisposition for certain locations □ CMV and TB tend to involve ileum □ Giardia, microsporidium tend to involve proximal small bowel □ Colon infections often due to CMV, C. difficile, Campylobacter, amebiasis, Salmonella, and Shigella ○ Mural thickening of esophagus suggests esophagitis, often due to candidiasis, CMV, or herpes simplex ○ Proctitis in homosexual men due to sexual activity may be due to Neisseria gonorrhoeae, chlamydia, or HSV ○ Focal mass-like wall thickening anywhere in GI tract should raise concern for malignancy (AIDS-related lymphoma, Kaposi sarcoma) – Lymphoma associated with intussusceptions • Lymph nodes ○ Mild generalized lymphadenopathy (< 1.5 cm) is usually reactive and may be 1st clue to HIV infection – May persist for years in absence of symptoms (i.e., persistent generalized lymphadenopathy) ○ More significant adenopathy (> 1.5 cm) suggests opportunistic infection (MAI, tuberculosis) or AIDSrelated lymphoma/Kaposi sarcoma – Necrotic mesenteric nodes from MAI or tuberculosis – Hyperenhancing lymph nodes in Kaposi sarcoma ○ AIDS-related lymphoma may be associated with discrete lesions in liver/spleen or focal mass in GI tract – GI tract most common extranodal site of involvement (75%), most often involving colon, ileum, and stomach • Kidney ○ Bilateral large kidneys with urothelial thickening due to HIV nephropathy ○ Focal hypodense lesions could reflect infection (tuberculosis, MAI, fungus) or AIDS-related lymphoma ○ Calcifications may be present in setting of Pneumocystis (similar to liver and spleen) or rarely MAI/CMV • Pancreas ○ Opportunistic infections can cause acute pancreatitis and pancreatic duct strictures (e.g., CMV, Cryptococcus, etc.)

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Ultrasonographic Findings • Kidney ○ HIV nephropathy: Normal sized or enlarged kidneys with increased echogenicity (kidney > liver) – May be associated with urothelial thickening in pelvis/intrarenal collecting system – Parenchymal heterogeneity and loss of corticomedullary differentiation ○ Hyperechoic foci or calcifications without posterior acoustic shadowing due to Pneumocystis, MAI, or CMV • Gallbladder 9

Abdominal Manifestations of Systemic Conditions

HIV/AIDS ○ GB wall thickening may be reactive due to hepatitis or secondary to opportunistic acute acalculous cholecystitis ○ Wall thickening and dilation of extrahepatic &/or intrahepatic bile ducts due to AIDS cholangiopathy • Liver ○ Opportunistic infections present as small hypoechoic nodules (microabscesses) scattered throughout liver ○ Pneumocystis may result in small hypoechoic nodules or tiny echogenic foci • Lymph nodes ○ Necrotic nodes most often due to MAI or tuberculosis

DIFFERENTIAL DIAGNOSIS Lymphoma Unrelated to HIV/AIDS • Nodal involvement more common, unlike AIDS, where extranodal involvement is disproportionately common • AIDS-related lymphoma often aggressive with widespread dissemination, whereas non-AIDS related lymphoma may present with early stage disease confined to nodes

Biliary Hamartomas • Multiple small cystic lesions scattered throughout liver • May mimic hepatic microabscesses, but patients are asymptomatic without signs of infection

Sarcoidosis • May present with multiple small hypodense lesions in liver and spleen (mimicking microabscesses) • Upper abdominal adenopathy frequently present, and may be mistaken for HIV-related adenopathy • Mediastinal and hilar lymphadenopathy, characteristic lung disease, and lack of symptoms may allow distinction

PATHOLOGY General Features • Etiology ○ HIV results in immunodeficiency through infection and lysis of CD4(+) T cells ○ HIV-infected patients have an increased risk of developing malignancies, particularly when coinfected by Epstein-Barr virus, herpesvirus, or papillomavirus – Incidence of AIDS-defining malignancies (AIDS-related non-Hodgkin lymphoma, Kaposi sarcoma) has dramatically with antiretroviral therapy – Risk of other malignancies, which are often atypically aggressive and occur at younger ages than normal, still higher in HIV patients – Non-Hodgkin lymphoma □ AIDS-defining malignancy (usually CD4 count < 100) that includes several types of lymphoma, including diffuse large B-cell and Burkitt lymphoma □ Strong tendency to arise in extranodal sites (especially GI tract), involve unusual locations, and present with advanced disease – Kaposi sarcoma □ Low-grade soft tissue sarcoma of vascular origin associated with HHV-8 infection ○ Infections more common in HIV patients even with CD4 counts > 200, although risk increases substantially with lower CD4 counts 10

– Many different AIDS-defining infections, including disseminated MAI, tuberculosis, Pneumocystis infection, recurrent bacterial pneumonias, persistent Cryptosporidium infection, chronic HSV, etc. □ Most occur when CD4 count < 200, but can rarely occur at higher CD4 counts

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute HIV infection may resemble mononucleosis, with fever, headaches, and body aches ○ Many patients with chronic HIV infection asymptomatic when effectively treated with antiretrovirals – Skin abnormalities and mild constitutional symptoms possible even without immunosuppression ○ Patients with advanced HIV/AIDS and immunosuppression may experience symptoms related to opportunistic infections (diarrhea, cough/shortness of breath, abdominal pain, etc.) – Some patients experience wasting syndrome with profound weight loss and chronic diarrhea • Other signs/symptoms ○ Patients with low CD4 counts frequently pancytopenic (anemia, thrombocytopenia, and lymphopenia) ○ Generalized lymphadenopathy and splenomegaly common even in absence of active infection • Clinical profile ○ Clinical profile varies from country to country – HIV in developing world spread primarily by vaginal sex (small proportions due to IV drug abuse and perinatal transmission) – HIV in USA disproportionately associated with IV drug abuse and homosexual sexual contact

Demographics • Age ○ Primarily adults, but perinatal transmission possible • Gender ○ Worldwide most cases in heterosexuals, with F > M • Epidemiology ○ > 35 million affected worldwide

Natural History & Prognosis • Multiple opportunistic infections and AIDS-related tumors unless antiretroviral drugs used to suppress HIV • AIDS defined as CD4 < 200 or development of AIDSdefining illness (either infection or malignancy)

Treatment • Antiretroviral drugs to preserve immune status • Antibiotics for bacterial infections and antiviral drugs for CMV infection

SELECTED REFERENCES 1.

Tonolini M et al: Mesenterial, omental, and peritoneal disorders in antiretroviral-treated HIV/AIDS patients: spectrum of cross-sectional imaging findings. Clin Imaging. 37(3):427-39, 2013

HIV/AIDS Abdominal Manifestations of Systemic Conditions

(Left) Sagittal ultrasound demonstrates a normal-sized right kidney , which is markedly echogenic, compatible with the patient's known HIV nephropathy. Unlike other forms of chronic renal failure, the kidneys in HIV nephropathy are often normal in size or enlarged. (Right) Transverse ultrasound demonstrates innumerable tiny calcifications in the spleen of an HIV patient, representing the sequelae of the patient's known prior Pneumocystis infection.

(Left) Coronal CECT in an AIDS patient demonstrates diffuse mass-like wall thickening and aneurysmal dilatation of a loop of small bowel in the left lower quadrant with internal enteric contrast . Note the extensive lymphadenopathy more superiorly. These findings are compatible with the patient's biopsy-proven AIDS-related non-Hodgkin lymphoma. (Right) Axial CECT in an AIDS patient demonstrates extensive mesenteric lymphadenopathy found to represent AIDS-related nonHodgkin lymphoma.

(Left) Axial CECT in an AIDS patient illustrates multiple hepatic masses , including a mass with internal hemorrhage , which were proven to be non-Hodgkin lymphoma. An unusual feature in this case is the mild obstruction of the intrahepatic bile ducts . (Right) Longitudinal ultrasound in a patient with AIDS demonstrates a large hypoechoic mass . Biopsy revealed this to represent AIDS-related B-cell nonHodgkin lymphoma.

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Abdominal Manifestations of Systemic Conditions

Tuberculosis KEY FACTS

IMAGING • Most common sites of involvement in abdomen are lymph nodes, GU tract, peritoneum, and GI tract ○ Abdominal lymphadenopathy is most common • Lymphadenopathy (tuberculous lymphadenitis) ○ Enlarged, centrally necrotic nodes with hypoattenuating centers and hyperattenuating enhancing rims ○ Nodes often calcify after healing • Tuberculosis peritonitis ○ Variables amounts of free or loculated complex ascites with infiltration of omentum ± discrete masses • Gastrointestinal tuberculosis ○ Ileocecal region affected in 90% of cases ○ Asymmetric wall thickening of ileocecal valve and medial cecum • Adrenal tuberculosis ○ Acute: Enlarged adrenals (often appears as discrete, centrally necrotic adrenal mass)

(Left) Axial CECT in an asymptomatic elderly man shows calcification of mesenteric nodes usually seen in elderly individuals who have had exposure to enteric mycobacteria, often from drinking unpasteurized milk. (Right) Axial CECT in a liver transplant recipient shows marked thickening of the omentum , peritoneum, and mesentery, with enlargement of mesenteric nodes . Loculated ascites was also present (not shown). This patient's reactivated TB with TB peritonitis was first acquired in his native country.

(Left) Spot film from a small bowel follow-through in a 25year-old immigrant from India shows deformity of the terminal ileum and cecum , with asymmetric thickening and stiffening of the bowel walls, ultimately found to represent TB. (Right) Coronal CECT in an immigrant patient demonstrates asymmetric thickening of the cecum, which has a coneshaped appearance in a patient with tuberculous colitis.

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○ Chronic: Small adrenals with dots of calcification and low signal on all MR sequences • Renal tuberculosis ○ Most common CT finding is renal calcification (50%) ○ Papillary necrosis is a very common early finding ○ Focal wedge-shaped hypodense areas, small hypodense nodules, or discrete renal abscess ○ Urothelial thickening, caseous debris, and strictures of calyces and infundibuli may lead to hydronephrosis • Hepatosplenic tuberculosis ○ Hepatosplenomegaly with hypodense nodules of variable size

CLINICAL ISSUES • Often presents with fever, weight loss, and abdominal pain • May or may not have evidence of pulmonary TB ○ Negative chest radiograph or negative tuberculin skin test does not exclude extrapulmonary TB

Tuberculosis

Abbreviations • Tuberculosis (TB)

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Definitions • Infection by Mycobacterium tuberculosis

IMAGING General Features • Best diagnostic clue ○ Most common sites of involvement in abdomen are lymph nodes, GU tract, peritoneum, and GI tract – Abdominal lymphadenopathy most common (2/3 cases) – GU tract is most common organ system involved

Imaging Recommendations • Best imaging tool ○ CECT

Radiographic Findings • Often no evidence of lung disease (CXR or CT can be normal) • Lymphadenopathy (tuberculous lymphadenitis) ○ Can range from increased number of normal-sized nodes to massively enlarged conglomerate nodal masses – Mesenteric and peripancreatic lymph nodes most commonly involved – Multiple groups often affected simultaneously ○ Enlarged, necrotic nodes with hypoattenuating centers and hyperattenuating enhancing rims on CT (40-60%) – Characteristic of caseous necrosis – Mixed attenuation nodes are also possible ○ Nodes calcify with healing: TB probably most common cause of mesenteric nodal calcification • Tuberculosis peritonitis ○ 3 imaging patterns: Wet, dry, and fibrotic fixed – Wet type: Large amount of free or loculated ascites □ Higher than water density due to protein/cellular content □ Complex ascites with septations or fibrinous strands – Dry type: Mesenteric and omental thickening, fibrous adhesions, and caseous nodules – Fibrotic fixed: Discrete masses in omentum with matted loops of bowel ± loculated ascites ○ CT is ~ 69% sensitive for TB peritonitis – Difficult to distinguish from carcinomatosis – Carcinomatosis more likely to demonstrate discrete implants or omental caking • Gastrointestinal tuberculosis ○ Ileocecal region affected in 90% of cases – Common site due to presence of lymph tissue and stasis of bowel contents in that location – Cecum and terminal ileum are usually contracted (cone-shaped cecum) with asymmetric wall thickening of ileocecal valve and medial cecum – Regional lymphadenopathy with central caseation ○ Involvement of stomach and proximal small bowel is rare

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– Stomach: Affects antrum and distal body, often simulating peptic ulcer disease – Duodenum: Wall thickening and luminal narrowing Hepatosplenic tuberculosis ○ Micronodular pattern – Innumerable 0.5–2.0 mm nodules may or may not be discretely visualized (most often hypodense on CT and hyperechoic on US) – May simply appear as hepatomegaly on CT ○ Macronodular pattern – CT □ Acute: Hypoattenuating nodules with ill-defined enhancing margins □ Chronic: Tuberculomas often calcify □ TB and histoplasmosis are most common causes of calcified granulomas – MR □ T1WI: Hypointense, minimally enhancing, honeycomb lesions □ T2WI: Hyperintense with less intense rim relative to surrounding liver □ Rim enhancement on post-gadolinium images Adrenal tuberculosis ○ Unilateral (10%) or bilateral (90%) ○ Acute: Enlarged adrenals (often appear as discrete centrally necrotic adrenal masses) ○ Chronic: Small adrenals with dots of calcification and low signal on all MR sequences ○ May cause adrenal insufficiency (most common cause in developing countries) Renal tuberculosis ○ 75% unilateral ○ CT findings – Most common CT finding is renal calcification (50%) □ Affected part of kidney often nonfunctional; global nonfunction and calcification = "putty" kidney – Papillary necrosis early finding (usually upper pole) – Focal wedge-shaped areas of low attenuation, multiple small hypodense nodules, or discrete renal abscess – Urothelial thickening, caseous debris, and strictures of calyces and infundibuli may lead to hydronephrosis ○ Intravenous urography: "Moth-eaten" calyx due to erosions and progression to papillary necrosis – Strictures of renal pelvis and infundibula – Caliectasis and hydronephrosis with irregular margins and filling defects due to caseous debris – Irregular pools of contrast due to parenchymal cavitation Ureteral tuberculosis ○ Usually secondary to renal TB ○ Thickened wall of ureter with strictures most common in distal 1/3 of ureter ○ Corkscrew/beaded ureter due to chronic fibrotic strictures Bladder tuberculosis ○ Decreased bladder volume with wall thickening, ulceration, and filling defects ○ Severe: Scarring small, irregular, calcified bladder Female genital tuberculosis

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

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Abdominal Manifestations of Systemic Conditions

Tuberculosis ○ Most commonly involves fallopian tubes (in 94% of cases) – Bilateral salpingitis with strictures ± occlusion ○ Can involve endometrium resulting in deformed, irregular endometrium on US • Male genital tuberculosis ○ Affects seminal vesicles or prostate gland, rarely testes ○ Can resemble a pyogenic abscess ± calcification • Pancreatic tuberculosis ○ Appears as mass mimicking cancer (caseated peripancreatic nodes involving pancreas) – US: Well-defined hypoechoic lesions – CT: Hypodense mass (usually pancreatic head) typically without pancreatic duct dilatation or vascular invasion

DIFFERENTIAL DIAGNOSIS Peritonitis • Nontuberculous peritonitis • Peritoneal metastases and lymphoma • Mesothelioma

PATHOLOGY General Features • Etiology ○ Primary infection from M. tuberculosis ○ Abdominal TB is usually secondary to pulmonary TB – CXR normal in 2/3 of patients with abdominal TB – Only 15% have active pulmonary disease ○ Other sources of abdominal infection with TB – Swallowing infected material – Hematogenous spread from active or latent infection – Direct extension from infected tissues

Microscopic Features • Caseating granulomas are characteristic • Microscopy and culture for mycobacteria

CLINICAL ISSUES Presentation

• Amebiasis • Crohn disease • Primary cecal malignancy

• Most common signs/symptoms ○ Abdominal TB often presents with fever, weight loss, and abdominal pain ○ Negative chest radiograph or negative tuberculin skin test does not exclude extrapulmonary TB – May or may not have evidence of pulmonary TB – May or may not have positive tuberculin test □ Possibly negative in immunosuppressed, malnourished, or severe disseminated disease • Other signs/symptoms ○ Adrenal tuberculosis – Addisonian presentation (adrenal insufficiency, hypotension, and electrolyte disturbances) ○ Gastrointestinal TB – Usually few or no symptoms (partial obstruction)

Lymphadenitis

Demographics

• Metastases or lymphoma • Whipple disease • Mycobacterium avium-intracellulare infection

• Epidemiology ○ Resurgence of TB – in immunocompromised patients (especially those with AIDS) – Drug-resistant strains of M. tuberculosis – Estimated 1/3 of world population infected with TB • Risk factors for TB ○ Immunocompromise (AIDS, transplant recipients, immunosuppressive drugs) ○ Poverty, homelessness, alcoholism, immigration from developing country, imprisonment

Miliary Hepatic Lesions • Hepatic metastases and lymphoma • Hepatic opportunistic infection • Sarcoidosis

Macronodular Hepatic Lesions • Hepatic metastases and lymphoma • Hepatic pyogenic abscess • Primary hepatic malignancy

Ileocecal Lesions

Renal Lesions • Renal papillary necrosis • Renal transitional cell carcinoma • Other infections ○ (e.g., pyelonephritis, xanthogranulomatous pyelonephritis)

Adrenal Lesions • Adrenal metastases and lymphoma • Primary adrenal neoplasm • Adrenal hemorrhage

Bladder Lesions • • • •

Bladder schistosomiasis Cytoxan cystitis Radiation-induced bladder calcification Calcified bladder carcinoma

Treatment • Surgery for emergent presentations • 6-9 month course of multidrug antituberculous chemotherapy ○ Most commonly used drugs include rifampin, isoniazid, pyrazinamide, and ethambutol ○ Exact drug regimen may vary based on resistance patterns

SELECTED REFERENCES 1.

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Prapruttam D et al: Tuberculosis-the great mimicker. Semin Ultrasound CT MR. 35(3):195-214, 2014

Tuberculosis Abdominal Manifestations of Systemic Conditions

(Left) Axial CECT in a young woman with AIDS demonstrates mesenteric and retroperitoneal lymphadenopathy. Some of the enlarged nodes have a caseated or low-density centrally necrotic appearance characteristic of mycobacterial infection. (Right) Axial CECT shows a large, complex cystic mass in the porta hepatis and pancreatic head region, representing conglomerate caseated, enlarged nodes due to Mycobacterium tuberculosis infection.

(Left) Axial CECT shows cavitary and multilobar bronchoalveolar infection of the lungs, typical of active tuberculosis. This patient was a young female college exchange student from Asia. (Right) Axial CECT in the same patient shows mural thickening of the cecum , along with regional mesenteric lymphadenopathy typical of intestinal and nodal involvement by TB.

(Left) Axial CECT show a small, nonfunctional, and partially calcified "putty" kidney , typical of chronic TB infection of the kidney. The patient had a known history of pulmonary TB. (Right) Axial NECT shows calcification from healed TB granulomas within retroperitoneal and retrocrural nodes . The left kidney is totally calcified and nonfunctional, an autonephrectomy or "putty" kidney due to chronic renal TB. Small focal calcifications were also present in the adrenals.

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Abdominal Manifestations of Systemic Conditions

Mononucleosis KEY FACTS

TERMINOLOGY

PATHOLOGY

• Illness due to infection with Epstein-Barr virus (EBV)

• EBV infection (human herpesvirus 4) ○ Replicates mainly in B lymphocytes but also in epithelial cells of pharynx and parotid duct • Splenomegaly and lymphadenopathy ○ Due to congestion with activated T lymphocytes

IMAGING • Splenomegaly in 60% of patients ○ Splenic rupture: Perisplenic and splenic subcapsular hematoma (sentinel clot) ○ Splenic infarct: Rare in mononucleosis, but may be due to transient thrombophilia predisposing to arterial thrombosis • Hepatomegaly ± parenchymal heterogeneity and periportal edema ○ ± gallbladder wall thickening: May be reactive due to EBV hepatitis • Generalized or upper abdominal lymphadenopathy

• Adolescents and young adults are most often affected ○ Uncommon in adults due to prior exposure/immunity • Acute symptoms (e.g., sore throat, fever, headache) typically resolve in 1 month ○ Fatigue/myalgias may persist for several months • Laboratory findings: Lymphocytosis, positive monospot test • Treatment is typically supportive

TOP DIFFERENTIAL DIAGNOSES

DIAGNOSTIC CHECKLIST

• Long differential, including other neoplastic, inflammatory, infectious, infiltrative, and hematologic diseases

• Consider mononucleosis in previously healthy adolescent or young adult with splenomegaly and lymphadenopathy

(Left) Axial CECT in a patient with mononucleosis shows clotted blood (sentinel clot) around an enlarged spleen and lower density free intraperitoneal hemorrhage . This spontaneous splenic rupture resolved with nonoperative management. (Right) Axial CECT in a patient with mononucleosis shows an enlarged spleen with presplenic hematoma as a result of splenic rupture. This patient recovered without surgery.

(Left) Axial NECT shows an enlarged spleen with highdensity adjacent sentinel clot , and lower density free intraperitoneal blood . (Right) Surgical specimen from the same patient shows a ruptured spleen, which was enlarged due to mononucleosis. The spleen was almost 20 cm in length, and a histologic exam showed that it was congested with activated T lymphocytes.

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CLINICAL ISSUES

Mononucleosis

CLINICAL ISSUES

Abbreviations

Presentation

• Infectious mononucleosis (IM)

• Protocol advice ○ Imaging not needed unless complications are suspected ○ Contrast-enhanced CT for complications

• Most common signs/symptoms ○ Fever, pharyngitis, adenopathy, malaise, palpable lymphadenopathy (often cervical) ○ Rare – Abdominal pain or falling hematocrit with splenic rupture, neurologic syndromes (e.g., Guillain-Barre, meningitis, or transverse myelitis) ○ Complications – Splenic rupture (often associated with sports injury) □ Typically occurs in 1st through 4th week of disease □ Most common cause of death in mononucleosis – Hepatomegaly/jaundice with severe EBV hepatitis • Other signs/symptoms ○ Lab findings: Lymphocytosis (± atypical lymphocytes); positive "monospot" test (rapid latex agglutination)

Radiographic Findings

Demographics

• Spleen ○ Splenomegaly – Common (60% of patients), even if spleen is not palpable on physical exam ○ Splenic rupture – Perisplenic and splenic subcapsular hematoma (sentinel clot sign on CT) – Enlarged spleen with areas of hypodensity on CT ○ Splenic infarct – Rare, but may be due to transient thrombophilia predisposing to arterial thrombosis – Wedge-shaped areas of splenic hypodensity on CT • Liver and biliary tract ○ Hepatomegaly ± parenchymal heterogeneity and periportal edema ○ Thickened gallbladder may be reactive to EBV hepatitis • Generalized or upper abdominal lymphadenopathy • Focal lesions (nodular proliferation of EBV-infected cells or lymphomatoid granulomatosis) very rarely in spleen and liver

• Age ○ Adolescents and young adults – EBV infection in children is often asymptomatic – Symptomatic infection is much more common in adolescents – Uncommon in adults due to prior exposure/immunity

Definitions • Illness due to infection with Epstein-Barr virus (EBV)

IMAGING General Features • Best diagnostic clue ○ Splenomegaly and abdominal lymphadenopathy in previously healthy adolescent or young adult

Imaging Recommendations

DIFFERENTIAL DIAGNOSIS Splenomegaly and Lymphadenopathy • Long differential, including neoplastic, inflammatory, infectious, infiltrative, and hematologic diseases ○ Always consider leukemia and lymphoma

PATHOLOGY General Features • Etiology ○ Infection with EBV (a type of herpesvirus) – Replicates mainly in B lymphocytes but also in epithelial cells of pharynx and parotid duct – Spread by saliva ("kissing disease" among adolescents) ○ Splenomegaly and lymphadenopathy – Due to congestion with activated T lymphocytes

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Natural History & Prognosis • Acute symptoms (e.g., sore throat, fever, headache) typically resolve in 1 month • Fatigue/myalgias may persist for several months • Rare associations ○ Acute interstitial nephritis, hemolytic anemia, myocarditis/conduction abnormalities, thrombocytopenia, upper airway obstruction

Treatment • Supportive care ○ Adequate hydration, analgesics, etc. • Corticosteroids, acyclovir (Zovirax), and antihistamines ○ Not recommended for routine treatment ○ Corticosteroids helpful for respiratory compromise ○ No definitive benefit for antivirals (such as acyclovir) • Avoid contact sports for minimum of 3-4 weeks due to risk of splenic rupture

DIAGNOSTIC CHECKLIST Consider • Consider mononucleosis in previously healthy adolescent or young adult with splenomegaly and lymphadenopathy • Imaging findings may mimic lymphoma or leukemia, but diagnosis usually confirmed easily by monospot test

Image Interpretation Pearls • Imaging mostly to evaluate complications, not for diagnosis

SELECTED REFERENCES 1.

Hedgire SS et al: Mono-belly and beyond: spectrum of imaging manifestations of EBV infection in the abdomen. Clin Imaging. 37(4):711-7, 2013

17

Abdominal Manifestations of Systemic Conditions

Cystic Fibrosis KEY FACTS

TERMINOLOGY • Recessively inherited disorder of epithelial chloride transport caused by mutation of CFTR gene • Cystic fibrosis (CF) increasingly seen to affect GI tract due to improving life expectancy

IMAGING • Most common sites of involvement are lungs, pancreas, bowel, liver, and exocrine glands • Pancreas ○ Complete fatty infiltration and replacement of parenchyma (often by end of teenage years) ○ Pancreatic cysts: Usually small (< 3 mm), but can be larger and can completely replace pancreas (cystosis) ○ Repeated episodes of acute pancreatitis with development of chronic pancreatitis • Liver ○ 30-50% develop hepatic steatosis ± hepatomegaly ○ Can develop multinodular cirrhosis in severe cases

(Left) Axial CECT shows the classic lipomatous replacement and pseudohypertrophy of the pancreas in a young adult patient with cystic fibrosis (CF). (Right) Axial CECT in the same patient shows dilated proximal small bowel and collapsed distal small bowel . Just proximal to the point of transition is the classic "small bowel feces sign" associated with mechanical small-bowel obstruction, with the obstruction caused by inspissated enteric contents (distal intestinal obstruction syndrome or DIOS).

(Left) Axial CECT demonstrates heterogeneous lipomatous replacement of the pancreatic parenchyma but less pseudohypertrophy. This 29-year-old woman had longstanding pancreatic exocrine dysfunction due to CF. (Right) Coronal CECT demonstrates simpleappearing cysts in the pancreatic head in a young patient with CF. While pancreatic cysts are often very small in CF patients, they can rarely be larger, as in this case.

18

• Biliary ○ Biliary abnormalities similar to primary sclerosing cholangitis (PSC) • Bowel ○ Inspissated fecal material resulting in proximal obstruction, most often in infants (meconium ileus) ○ Obstruction can also occur in adults: Distal intestinal obstruction syndrome (DIOS) ○ Increased risk for intussusception ○ Chronically distended appendix may be difficult to distinguish from acute appendicitis

CLINICAL ISSUES • Overall prognosis for CF has dramatically improved, with average life expectancy now 35-40 years • Respiratory failure most common cause of mortality, with liver disease 2nd leading cause of death • Pancreatic insufficiency most common (~ 85%) GI manifestation of CF

Cystic Fibrosis

Abbreviations • Cystic fibrosis (CF)

Definitions • Recessively inherited disorder of epithelial chloride transport caused by mutation of CF transmembrane conductance regulator (CFTR ) gene ○ Pulmonary manifestations are primary cause of morbidity and mortality ○ CF increasingly seen to affect GI tract due to improved life expectancy

IMAGING General Features • Best diagnostic clue ○ Diffuse fatty replacement of pancreas is most common abdominal imaging finding • Location ○ Most common sites of involvement are lungs, pancreas, bowel, liver, and exocrine glands

CT Findings • Pancreatic manifestations ○ Early childhood: Heterogeneous attenuation of pancreas ○ Later childhood: Complete fatty replacement of parenchyma (often by teenage years) ○ Pancreatic cysts: Usually simple in appearance – Related to inspissated secretions which lead to ductal obstruction – Cysts are usually small (< 3 mm), but can be larger – Cysts may diffusely replace pancreas (cystosis) – Usually occur in patients in their 20s, and may be symptomatic as result of cyst hemorrhage ○ Repeated episodes of acute pancreatitis with development of chronic pancreatitis – Pancreatic ductal strictures, dilatation, beading, etc. ○ May have scattered calcifications (< 10% of patients) ○ Increased risk of pancreatic cancer (very rare)

MR Findings • Enlarged pancreas with diffuse fatty infiltration appears hyperintense on T1WI • Pancreas can also appear abnormally hypointense on T1WI due to chronic pancreatitis and fibrosis • Pancreatic cysts well demonstrated on T2WI and MRCP (hyperintense)

Ultrasonographic Findings • Pancreas may be barely identifiable as result of diffuse fibrofatty replacement

Other Abdominal Findings • Liver ○ 30-50% develop hepatic steatosis ± hepatomegaly – Can be visualized with US, CT, or chemical shift MR – Fatty liver usually asymptomatic and does not correlate with development of CF-related cirrhosis ○ Cirrhosis in 5-15% of all CF patients with portal hypertension in 1-8% • Biliary

○ Gallstones in up to 1/4 of patients with CF, often with nonspecific gallbladder wall thickening and sludge ○ Microgallbladder in 30% of CF patients at autopsy – Probably due to chronic stenosis or atresia of cystic duct (does not usually cause symptoms) ○ May develop bile duct abnormalities very similar to primary sclerosing cholangitis (PSC), including strictures, bile duct wall thickening, biliary obstruction, etc. – May develop focal biliary fibrosis (> 3/4 of patients with CF older than 24 years) □ Periductal thickening and fibrosis due to thick secretions within duct and reactive inflammation □ Focal thickening of bile duct with changes in adjacent liver parenchymal density/signal □ US: Hyperechoic periportal thickening and diffuse hepatic hyperechogenicity • Esophagus ○ Gastroesophageal (GE) reflux seen in 27% of patients younger than 5 years and increases with age • Bowel ○ frequency of peptic ulcer disease (gastric or duodenal) ○ Obstruction – Bubbly fecal mass within bowel causing proximal obstruction, most often in infants (meconium ileus) – Obstruction can also occur in adults: Distal intestinal obstruction syndrome (DIOS) (previously known as meconium ileus equivalent) □ Obstruction results from thickened intestinal secretions, poor motility, and formation of masslike fecal material which obstructs bowel □ Usually obstructs at distal ileum or right colon (rarely at distal rectum) □ Water-soluble contrast enema might be able to reduce obstruction ○ Increased risk for intussusception – More common in older patients – Most often ileocolic intussusception, usually due to inspissated fecal material acting as lead point – US: "Doughnut" or pseudokidney appearance – CT: "Target" sign of edematous bowel and intermixed mesenteric fat – Water-soluble contrast enema can be used for reduction, but high rates of recurrence ○ Chronically distended appendix common with internal inspissated high-density material – Differentiating acute appendicitis from chronic distention is difficult with imaging ○ Abnormalities of colon can include proximal colonic wall thickening, proliferation of fat surrounding the colon, and pericolonic fat stranding – Benign pneumatosis due to air dissecting below diaphragm into bowel wall due to lung disease – Increased susceptibility to pseudomembranous colitis – Increased risk of colon cancer – Rectal mucosal prolapse usually in younger patients • Renal ○ Nephrolithiasis in 3-6% CF patients ○ Interstitial nephritis due to antibiotics and amyloidosis will likely become more common as patients live longer

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

19

Abdominal Manifestations of Systemic Conditions

Cystic Fibrosis

Pancreatic Lipomatous Pseudohypertrophy • Diffuse enlargement and fatty replacement of pancreas • Associated with chronic liver disease; no signs of CF

Shwachman-Diamond Syndrome • Pancreatic lipomatosis associated with short stature • Appearance of pancreas is identical to CF

Normal Fatty Lobulation • Fatty replacement of pancreatic parenchyma with mild glandular atrophy • Common in elderly, obese, and diabetic patients

Chronic Pancreatitis • Pancreatic atrophy, parenchymal and ductal calcifications, and pancreatic ductal beading, irregularity, and dilatation

Pancreatic Cystic Neoplasms (IPMN, etc.) • May be indistinguishable from CF-related pancreatic cysts without clinical history

PATHOLOGY General Features • Etiology ○ Mutations of CFTR gene lead to multisystem pathology ○ Disruption of chloride ion, bicarbonate, and water transport in duct cells ○ Primary ductal cell chloride channel abnormality results in dehydrated protein-rich secretions obstructing proximal ducts – Leads to acinar cell destruction, fibrosis, and exocrine insufficiency – Also causes ductal obstruction leading to lung infections, biliary obstruction, etc. • Genetics ○ Mutations in CFTR gene ○ Autosomal recessive gene on chromosome 7

Lab • Positive sweat test • Genotyping has proved useful in identifying gene carriers; antenatal diagnosis and treatment

CLINICAL ISSUES Presentation • Clinical profile ○ Usually diagnosed in infants with meconium ileus, lung infections, etc. – Until recently, patients died in childhood of pulmonary infections and respiratory failure – Longer survival now reveals other multisystem manifestations of cystic fibrosis ○ 7% of CF patients do not present until adulthood – Of these, 26% present with GI symptoms and 4% with pancreatitis ○ Symptoms of pancreatic dysfunction – Steatorrhea, malabsorption, fat intolerance □ Pancreatic insufficiency usually present from birth 20

– Repetitive acute pancreatitis leading to chronic pancreatitis □ Pancreatitis in 10% of CF patients – Endocrine (diabetes) and exocrine dysfunction ○ Symptoms of hepatobiliary dysfunction – Inspissated secretions obstruct bile ducts and caustic bile acts on adjacent parenchyma – Liver disease can vary from asymptomatic elevation in liver function tests to end-stage liver disease and cirrhosis – 10-20% of patients develop chronic liver disease (including cirrhosis and portal hypertension) – Cholelithiasis in 10% of patients ○ Intestinal manifestations – Intestinal obstruction □ Usually in infancy (meconium ileus), but may occur in adults as well (DIOS or meconium ileus equivalent) – Intussusceptions (1% of patients) ○ Infertility in males (azoospermia, turbid semen)

DIFFERENTIAL DIAGNOSIS

Demographics • Age ○ Children most affected ○ Patients reaching adulthood represent rapidly growing percentage of CF population • Ethnicity ○ More common in Caucasians – Most common inherited fatal disease in Caucasians • Epidemiology ○ CF prevalence: 1 in 3,500 ○ 85–90% of CF patients have pancreatic exocrine gland insufficiency – Cystic fibrosis is major cause of pancreatic exocrine failure in childhood ○ 30-50% of CF patients have pancreatic endocrine gland dysfunction

Natural History & Prognosis • Overall prognosis for CF has dramatically improved due to screening and better treatment, with average life expectancy now 35-40 years • Respiratory failure most common cause of mortality ○ Liver disease is 2nd leading cause of death • Pancreatic insufficiency most common (~ 85%) GI manifestation of CF ○ Varies depending on degree of ductal obstruction by mucus, which leads to exocrine gland atrophy, progressive fibrosis, and cyst formation ○ CF may predispose to pancreatic cancer

Treatment • Aggressive nutritional and pancreatic enzyme therapy • DIOS usually treatable with hydration, laxatives, or water soluble contrast enema although severe cases may require surgery

SELECTED REFERENCES 1.

Keyzer C et al: Cystic fibrosis: unenhanced CT description of the appendix in asymptomatic adults. AJR Am J Roentgenol. 202(4):759-64, 2014

Cystic Fibrosis Abdominal Manifestations of Systemic Conditions

(Left) Axial CT image shows diffuse pneumatosis of the transverse and left colon. The patient was completely asymptomatic, and this was felt to be benign pneumatosis due to gas dissecting from the chest into the bowel wall as a result of the patient's lung disease. (Right) Axial NECT in a 24-year-old woman with CF shows an unusually severe degree of pancreatic calcification . Scattered, small calcifications are a more common finding in this disease.

(Left) Axial T2WI in a 16-yearold girl with CF demonstrates complete fatty replacement of the body and tail of the pancreas. Note that the pancreas consequently shows high T1WI signal. (Right) Coronal MRCP in the same patient shows a septate cystic mass in the pancreatic head that mimics a cystic neoplasm. However, pancreatic cysts of variable size are commonly encountered in patients with CF.

(Left) Axial CECT in a 31-yearold man shows classic cystic bronchiectasis in the lungs. Many patients are being kept alive longer with better medical care and even lung transplantation, resulting in an increased prevalence of extrapulmonary manifestations of CF. (Right) Axial CECT in the same patient shows that the liver is small and cirrhotic with obvious signs of portal hypertension, including splenomegaly and large varices . The pancreas shows fatty replacement .

21

Abdominal Manifestations of Systemic Conditions

Sickle Cell Anemia KEY FACTS

TERMINOLOGY • Inherited hemolytic anemia arising due to abnormal hemoglobin, resulting in deformation of red blood cells and leading to microvascular occlusions and infarcts

IMAGING • Spleen ○ Splenic autoinfarction: Absent or small calcified spleen ○ Massive splenic infarction: Rare complication defined as when > 50% of spleen is infarcted ○ Splenic sequestration: Massive splenomegaly ○ Splenic abscess: Usually due to prior infarcts • Gallbladder: Gallstones in young patients • Extramedullary hematopoiesis: Most commonly paravertebral soft tissue masses of homogeneous density • Kidneys ○ Papillary necrosis on CT urography ○ Large kidneys in early phase of disease; gradual atrophy with development of chronic renal failure

(Left) Axial NECT in a patient who presented with sickle cell anemia and severe left upper quadrant pain demonstrates a heavily calcified and heterogeneous spleen , indicating chronic and possibly acute infarction. (Right) Splenectomy specimen from the same patient illustrates a mottled spleen with capsular discoloration that was heavily calcified on microscopy.

(Left) Axial NECT in a patient with homozygous sickle cell anemia demonstrates a small and heavily calcified spleen , also known as autosplenectomy. (Right) Axial CECT in a patient with sickle cell anemia demonstrates multiple wedgeshaped hypodense areas in the spleen, representing massive splenic infarction, an uncommon complication that rarely results in the formation of a splenic abscess.

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• Bones ○ Widened medullary spaces, thinning of cortex, coarsening of trabecular pattern, and osteopenia ○ Osteonecrosis and multiple bone infarcts – High T2WI MR signal in affected areas with serpiginous low T2 signal outline (double-line sign) ○ H-shaped or "Lincoln log" vertebrae – Cortical thinning leads to endplate deformities ○ Osteomyelitis ○ Persistence of red (cellular) marrow in bones with lowsignal marrow on T1WI – Demand for increased production of RBCs prevents normal conversion of red to yellow marrow • Findings of iron deposition due to repetitive transfusions ○ Hyperdense liver on NECT ○ Liver, spleen, and bone marrow abnormally low signal on all MR pulse sequences (particularly on T2WI) ○ Involved organs demonstrate characteristic signal loss on in-phase GRE images

Sickle Cell Anemia

Abbreviations • Sickle cell anemia (SCA)

Definitions • Inherited hemolytic anemia arising due to abnormal hemoglobin (hemoglobin S), resulting in deformation of red blood cells and leading to microvascular occlusions and infarcts

IMAGING General Features • Best diagnostic clue ○ Small, densely calcified spleen on CT ○ Cholelithiasis in a young African American patient

CT Findings • Spleen ○ Splenic autoinfarction: Absent or small calcified spleen ○ Massive splenic infarction – Splenic infarcts usually small and repetitive, leading to autoinfarction – Massive splenic infarction defined as when > 50% of spleen is infarcted – Often no precipitating factor, but may be associated with hypoxia (high altitude or mountain climbing) ○ Splenic abscess: Rare (< 1%) complication usually seen in patients with persistent splenomegaly (rather than autoinfarction) and massive infarcts ○ Splenic sequestration: Often associated with massive splenomegaly • Gallbladder: Gallstones in young patients • Extramedullary hematopoiesis: May have many different manifestations, including paravertebral soft tissue masses (homogeneous soft tissue density), hepatosplenomegaly, or perinephric soft tissue "rind" encasing kidneys • Liver: Hyperdense liver due to repeated transfusions • Kidneys ○ Papillary necrosis on CT urography (blunted, irregular calyces, "golf ball-on-tee" appearance, etc.) ○ Large kidneys in early phase of disease; gradual atrophy with development of chronic renal failure ○ Renal medullary carcinoma – More common in patients with sickle cell trait than with sickle cell disease – Very rare, highly aggressive malignancy with high mortality and early metastatic disease – Poorly marginated, heterogeneous renal mass with infiltrative appearance (similar to transitional cell carcinoma or lymphoma) • Bones ○ Avascular necrosis and multiple bone infarcts ○ H-shaped vertebrae with endplate deformities ○ Osteomyelitis

MR Findings

○ Demand for increased production of RBCs (due to RBC destruction and anemia) prevents normal conversion of red to yellow marrow ○ Stimulation of RBC production leads to widened medullary spaces, thinning of cortex, coarsening of trabecular pattern, and osteopenia ○ T1 images of skull demonstrate low-signal widening of diploic spaces due to bone marrow expansion ○ Cortical thinning leads to endplate deformities of vertebral bodies • Multiple medullary bone infarcts and avascular necrosis (especially humeral and femoral heads) ○ High T2 signal in affected areas with serpiginous low T2 signal outline (double-line sign) • Findings of iron deposition (hemosiderosis) due to repetitive blood transfusions ○ Liver, spleen, and bone marrow abnormally low signal on all pulse sequences (particularly on T2WI) ○ Involved organs demonstrate characteristic signal loss on in-phase GRE images (opposite of steatosis) ○ Iron deposition can be quantified using MR (usually GRE sequences with multiple TEs)

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Ultrasonographic Findings • Heterogeneous, coarsened liver parenchyma ± hepatomegaly • Gallstones • Increased renal echogenicity

Radiographic Findings • Radiography ○ Chest x-ray – Enlarged heart due to anemia – Pulmonary opacities due to infarcts and hemorrhage, bacterial pneumonia, or acute chest syndrome – H-shaped or "Lincoln log" vertebrae in spine – Extramedullary hematopoiesis with paraspinal soft tissue thickening and enlargement ○ Abdominal radiograph – Small, calcified spleen – Splenomegaly due to sequestration syndrome ○ Skull radiograph – Marrow expansion with thickened, striated appearance of skull ○ Extremity radiographs – Patchy sclerosis and lucencies due to infarcts – Osteonecrosis (most often femoral/humeral heads) – Bone destruction due to osteomyelitis (Salmonella) ○ Hand radiographs – Hand-foot syndrome with thick periostitis and subperiosteal new bone

Imaging Recommendations • Best imaging tool ○ NECT to visualize calcified spleen ○ US to visualize gallstones ○ Radiographs or CT for pulmonary and spinal findings

• Persistence of red (cellular) marrow in bones with lowsignal marrow on T1WI

23

Abdominal Manifestations of Systemic Conditions

Sickle Cell Anemia

DIFFERENTIAL DIAGNOSIS Asplenia • Congenital absence of spleen which is often associated with other congenital anomalies

Splenectomy • History of surgical removal of spleen

Papillary Necrosis From Other Causes • Analgesic use (especially phenacetin), diabetes, renal vein thrombosis, renal tuberculosis, congestive heart failure, cirrhosis, hemophilia, etc.

Bone Infarcts From Other Causes • Trauma, steroid use, lupus erythematosus, Gaucher disease, hemophilia, thalassemia, etc.

PATHOLOGY General Features • Etiology ○ Genetically inherited disorder of hemoglobin molecule – Homozygous sickle cell (HGSC) due to point mutation in gene coding for -globin synthesis – Deformation of hemoglobin molecule distorts RBCs, creating elongated shape (sickle cells) □ Hemoglobin chains polymerize when deoxygenated, resulting in distorted RBC morphology (sickling) □ Sickling leads to microvascular obstruction/occlusion in multiple organs • Genetics ○ Autosomal recessive disorder – 1st disease found to have molecular/genetic etiology – Most common genetic disorder in African Americans ○ Sickle cell disease requires 2 sickle cell hemoglobin genes and accounts for 60-70% of cases ○ Sickle trait results when patient has only 1 abnormal sickle cell gene (30-40% of cases) – Patients with sickle cell trait typically asymptomatic with normal life expectancy, no anemia, no pain crises, and no susceptibility to infections – Associated with risk for renal medullary carcinoma ○ Some patients may have 1 copy of sickle cell hemoglobin gene and 1 copy of another abnormal hemoglobin molecule (such as -thalassemia) – Patients usually symptomatic, but less so compared to standard sickle cell disease ○ In Africa, SCA and sickle trait have been shown to reduce susceptibility to malaria (Plasmodium falciparum) ○ SCA often detected by genetic screening programs in newborns

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute, painful vasoocclusive crisis (may occur several times each year) – May be precipitated by cold weather, low oxygen levels (such as when flying), dehydration, or stress – Can affect any part of body (bones, abdomen, etc.) 24

– Patients often also have chronic low-level pain ○ Acute chest syndrome: Chest pain, fever, cough ○ Hand-foot syndrome: Dactylitis with severe pain and swelling of hands/feet (usually children < 3 years old) ○ Fatigue and poor stamina due to chronic anemia ○ Lab findings: Mild to moderate anemia (hematocrit of 20-30%), reticulocytosis, elevated lactate dehydrogenase (LDH), sickled RBCs on peripheral blood smear • Other signs/symptoms ○ Strokes may be clinically silent or symptomatic ○ Biliary colic and cholecystitis due to gallstones ○ Pulmonary hypertension ○ High-output cardiac failure due to anemia

Demographics • Age ○ Usually diagnosed in newborns, but symptoms first manifest after 6 months • Epidemiology ○ Endemic in African Americans – 1:5,000 infants overall and 1:500 African American newborns in USA

Natural History & Prognosis • Painful vasoocclusive crises present in 1/2 of SCA patients prior to 5 years of age • Acute chest syndrome accounts for 25% of deaths ○ Other causes include stroke, sepsis, and acute sequestration syndrome ○ Acute sequestration syndrome – Significant percentage of blood volume sequestered in organ (most often spleen) – May be life threatening, resulting in vascular collapse • Prognosis dramatically improved with more sophisticated therapies, with median survival in USA now 40-50 years ○ In adulthood, end organ failure (especially lungs and kidney) has major impact on survival

Treatment • Pain control in acute pain crises • Hydroxyurea can hemoglobin levels and can help patients with symptomatic anemia and pain symptoms • Transfusions utilized in select situations, including acute severe anemia, acute chest syndrome, and acute strokes ○ Iron chelation agents may be needed to treat resultant iron overload as result of multiple transfusions • Pain control, oxygen, antibiotics, and transfusions for acute chest syndrome • Bone marrow or stem cell transplant can be curative

DIAGNOSTIC CHECKLIST Consider • Consider sickle cell anemia in young African American patients when confronted with absent or small/calcified spleen, gallstones, or characteristic bone findings

SELECTED REFERENCES 1.

Orphanidou-Vlachou E et al: Extramedullary hemopoiesis. Semin Ultrasound CT MR. 35(3):255-62, 2014

Sickle Cell Anemia Abdominal Manifestations of Systemic Conditions

(Left) Coronal coned-down MIP view from a CT IVP demonstrates blunting of the right lower pole calyx with contrast extravasation ("golf ball-on-tee" appearance) within the papilla of the right lower pole calyx, consistent with papillary necrosis. (Right) Axial CECT in a young child with sickle cell trait demonstrates an aggressive, infiltrative hypodense mass in the right kidney with adjacent lymphadenopathy . This was found to represent a renal medullary carcinoma.

(Left) Coronal NECT demonstrates the characteristic H-shaped lumbar vertebra associated with sickle cell disease. Note the presence of sclerosis in the femoral head , compatible with avascular necrosis. This patient required a total left hip replacement 3 months later. (Right) Axial T2 MR demonstrates markedly low signal of both the liver and spleen in a patient with iron deposition due to repetitive transfusions.

(Left) Coronal T2 FS MR demonstrates serpiginous high T2 signal in the distal femur and proximal tibia. Affected areas show a characteristic double-line sign with adjacent hyperintense and hypointense rims around their margins, characteristic of a bone infarct. (Right) Coronal CECT demonstrates multiple, bilateral paraspinal soft tissue masses , a characteristic appearance of extramedullary hematopoiesis.

25

Abdominal Manifestations of Systemic Conditions

Amyloidosis KEY FACTS

TERMINOLOGY • Group of diseases characterized by deposition of abnormal protein (amyloid) in various tissues ○ May be systemic (involving multiple organs in 80%) or localized (in single organ or tissue in 20%) ○ Primary: Due to monoclonal plasma cell dyscrasia (associated with no other underlying disease) ○ Secondary: Develops in setting of a number of different chronic inflammatory diseases

IMAGING • CT findings ○ Acute disease: Enlarged kidneys ○ Chronic disease: Small kidneys with cortical thinning ○ Bowel wall thickening, distension, intramural hemorrhage, and intussusceptions – Wall thickening can be focal or diffuse ± calcification ○ Hepatosplenomegaly – Patchy or diffuse hypoattenuation ± calcification

(Left) Axial NECT shows an abnormally hypodense and mildly enlarged liver and spleen in this patient with biopsy-proven primary amyloid of the liver. (Right) Spot film from a small bowel followthrough shows diffuse fold thickening throughout the jejunum. This is a very nonspecific finding, one that required biopsy for the diagnosis of amyloidosis.

(Left) Axial CECT in a patient with amyloidosis demonstrates rind-like soft tissue thickening surrounding the left kidney with internal calcification . (Right) Coronal CECT in the same patient demonstrates similar thickening and calcification surrounding the left kidney, as well as a more focal soft tissue mass (amyloidoma) in the adjacent retroperitoneum.

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○ Retroperitoneal soft tissue infiltration ± calcification resembling retroperitoneal fibrosis • MR findings ○ Focal amyloid involvement may be low signal on T2WI • Fluoroscopic findings ○ Stomach: Thick folds (which may appear nodular or masslike) ± calcification ○ Small intestine: Symmetrical thickening of folds, impaired motility, and slow transit ○ Colon: Luminal narrowing, loss of haustrations, and thickened transverse folds

CLINICAL ISSUES • Symptoms depend on site of protein deposition • Most common sites are kidneys, heart, liver, and GI tract • Renal failure due to amyloid deposition in kidneys is most common cause of death (50%) • GI tract involvement: GI bleeding, intestinal dysmotility, malabsorption, and protein-losing gastroenteropathy

Amyloidosis

DIFFERENTIAL DIAGNOSIS

Definitions

Varies Depending on Organ of Involvement

• Group of diseases characterized by deposition of abnormal protein (amyloid) in various tissues ○ May be systemic (involving multiple organs in 80%) or localized (in single organ or tissue in 20%) ○ Classified based on type of protein being deposited – 30 different amyloidogenic proteins in humans • Primary: Due to monoclonal plasma cell dyscrasia (associated with no other underlying disease) • Secondary: Develops in setting of a number of different chronic inflammatory diseases

• Other causes of hepatosplenomegaly, small bowel thickening, and renal disease much more common

IMAGING General Features • Best diagnostic clue ○ Small bowel wall thickening and hypomotility in patient with underlying chronic illness

Imaging Recommendations • Best imaging tool ○ Small bowel enteroclysis or small bowel follow-through for intestinal involvement; CECT for other organs

Radiographic Findings • Small intestine: Symmetrical thickening of folds, impaired motility, and slow transit • Stomach: Thickened folds (which may appear nodular or mass-like) ± calcification • Colon: Luminal narrowing, loss of haustrations, and thickened transverse folds

PATHOLOGY General Features • Etiology ○ Primary form (i.e., amyloidosis AL) – Bone marrow overproduction of light chain (AL protein) portion of antibody protein – Can occur in association with myeloma, Waldenstrom macroglobulinemia, or non-Hodgkin lymphoma – Most common type in Western world ○ Secondary form (i.e., amyloidosis AA) – Associated with underlying chronic inflammatory illnesses (rheumatoid arthritis, Reiter syndrome, ankylosing spondylitis, Sjögren syndrome, tuberculosis, osteomyelitis) ○ Dialysis-related amyloidosis – More likely with prolonged dialysis • Genetics ○ Familial amyloidosis (i.e., amyloidosis TTR) is rare form of inherited amyloidosis (autosomal dominant) ○ Familial Mediterranean fever associated with amyloidosis

Microscopic Features • Extracellular deposition of insoluble fibrillar proteins that stain positive with Congo red stain

CLINICAL ISSUES

CT Findings

Presentation

• Genitourinary tract ○ Acute disease: Enlarged kidneys ○ Chronic disease: Small kidneys with cortical thinning ○ Focal masses (amyloidomas) may develop in kidneys ○ Perinephric mass-like soft tissue thickening extending downwards along ureters • Gastrointestinal tract ○ Small bowel, large bowel, and stomach can be involved – Bowel wall thickening, distension, intramural hemorrhage, and intussusceptions – Wall thickening can be focal or diffuse ± calcification □ Can be nodular and mimic tumor/mass ○ Hepatosplenomegaly – Patchy or diffuse parenchymal hypoattenuation ± calcification – Spleen at increased risk of spontaneous rupture ○ Gallbladder wall thickening ○ Mass-like amyloidomas in soft tissues ± calcification ○ Retroperitoneal soft tissue infiltration ± calcification resembling retroperitoneal fibrosis ○ Lymphadenopathy ± calcification

• Most common signs/symptoms ○ Symptoms depend on site of protein deposition ○ Most common sites are kidneys, heart, and liver – Renal failure due to amyloid deposition in kidneys: Most common cause of death (50%) – Heart failure: 2nd most common cause of death – Peripheral neuropathy is common symptom – GI tract involvement: GI bleeding, intestinal dysmotility, malabsorption, and protein-losing gastroenteropathy

MR Findings

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Treatment • Depends on etiology and protein type deposited ○ Primary: Stem cell transplantation ○ Secondary: Treat underlying disease (e.g., myeloma, tuberculosis) ○ Dialysis-related amyloidosis: Renal transplantation ○ Hereditary amyloidosis: Liver transplantation (protein produced by liver)

SELECTED REFERENCES 1.

Loizos S et al: Amyloidosis: review and imaging findings. Semin Ultrasound CT MR. 35(3):225-39, 2014

• Focal areas of amyloid involvement tend to be low signal on T2WI and intermediate to high signal on T1WI

Ultrasonographic Findings • Enlarged, echogenic kidneys in acute setting 27

Abdominal Manifestations of Systemic Conditions

Sarcoidosis KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Relatively common, chronic, multisystem disease of unknown origin characterized by presence of noncaseating epithelioid granulomas

• Diverse clinical presentations ○ Classic: Young African American woman with chest symptoms • Hypercalcemia, hypercalciuria, hypergammaglobulinemia, anemia, leukopenia • 3 well-recognized, but uncommon, hepatic syndromes: Chronic intrahepatic cholestasis, portal hypertension, and Budd-Chiari syndrome • Angiotensin-converting enzyme elevated in 60% of patients with sarcoidosis; nonspecific and generally not useful in following course of disease

IMAGING • Can affect almost every organ ○ Most common site of involvement is lung ○ Also lymph nodes, spleen, liver, eyes, skin, salivary glands, nervous system, heart ○ Less common: Bones, GI, GU • Most common abdominal imaging finding is nonspecific hepatosplenomegaly ○ Diffuse parenchymal heterogeneity or multinodular pattern in liver, spleen, or both ○ Multiple low-attenuation nodules on CT and MR ○ Upper abdominal lymphadenopathy is often present • Advanced disease may cause or simulate cirrhosis

(Left) Axial NECT shows bilateral hilar lymphadenopathy in the thorax, including some calcification. (Right) The lung windows in the same case show micronodularity along the bronchial tree, characteristic of pulmonary sarcoid.

(Left) Axial CECT in the same case shows a nodular liver with widened fissures; this appearance might be mistaken for cirrhosis. Subtle hypodense foci in the liver and spleen indicate the granulomatous nature of the pathology. (Right) In H&E stain of a photomicrograph, a large epithelioid, noncaseating granuloma is seen in a liver biopsy from a case of sarcoidosis with ductopenia. (Courtesy J. Misdraji, MD.)

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DIAGNOSTIC CHECKLIST • Both lung disease and nodes may be FDG avid and mimic malignancy • Do not assume that heterogeneous hepatomegaly and abdominal lymphadenopathy are always malignant

Sarcoidosis

Definitions

MR Findings

• Relatively common, chronic, multisystem disease of unknown origin characterized by presence of noncaseating epithelioid granulomas

• T1WI ○ When visualized, nodules appear hypointense to adjacent liver parenchyma – May disappear on delayed contrast-enhanced T1WI • T2WI ○ Hypointense nodules ○ Lace-like fibrosis (hyperintense bands)

Synonyms

IMAGING General Features • Best diagnostic clue ○ Multifocal small hypodense lesions (granulomas) in liver and spleen in young patient with lymphadenopathy • Location ○ Can affect almost every organ ○ Most common: Lung – Common: Lymph nodes, spleen, liver, eyes, skin, salivary glands – Less common: Bones, nervous system, heart, GI, GU • Size ○ Granulomas are generally 50-300 μm – Large nodules may be up to 2 cm – Usually remain smaller than 2 mm in diameter, even though they may aggregate into larger clusters

Ultrasonographic Findings • Grayscale ultrasound ○ Nonspecific, diffuse parenchymal heterogeneity – May mimic steatosis or cirrhosis ○ Granulomas: Hypoechoic nodules

Nuclear Medicine Findings

Abdominal Manifestations of Systemic Conditions

• Boeck sarcoid

• Genitourinary ○ Most common: Calculi due to hypercalcemia ○ Uncommon: Interstitial nephritis (striated nephrogram) ○ Rare: Focal, soft tissue, renal masses

TERMINOLOGY

• FDG PET scan ○ Both lung disease and nodes may be FDG avid and mimic malignancy • Gallium scan ○ Ga-67 localizes in areas of granulomatous infiltrates; however, nonspecific finding

CT Findings

Imaging Recommendations

• Lymphadenopathy ○ Upper abdominal adenopathy is common, may simulate lymphoma ○ Usually accompanied by mediastinal adenopathy • Hepatosplenic involvement ○ Most common finding is nonspecific hepatosplenomegaly – Liver involvement can be found on biopsy in up to 75% – Splenic involvement in ~ 25% ○ Diffuse parenchymal heterogeneity or multinodular pattern in liver, spleen, or both ○ Innumerable small (< 15 mm) low-density nodules before contrast agent injection – May become isodense with liver parenchyma on delayed CECT ○ Advanced disease may cause or simulate cirrhosis – May especially mimic primary biliary cirrhosis (lace-like fibrosis plus lymphadenopathy) • Thoracic ○ Bilateral hilar and mediastinal lymphadenopathy (especially right paratracheal) ○ Interstitial ± alveolar disease – Beading or irregular thickening of bronchovascular bundles ○ May progress to conglomerate masses, bronchiectasis, pulmonary nodules ± cavitation ○ Pleural effusion unusual (< 5%) • Gastrointestinal ○ GI tract involvement in 1% of cases ○ Mostly gastric; ulceration or mural infiltration ○ Usually asymptomatic

• Best imaging tool ○ CT and MR are more sensitive than US – Able to show full extent of abdominal involvement • Protocol advice ○ CT or MR followed by biopsy

DIFFERENTIAL DIAGNOSIS Primary Biliary Cirrhosis (PBC) • May also have heterogeneous hepatomegaly, lymphadenopathy, lace-like fibrosis • Diagnose by clinical setting and AMA(+) (antimitochondrial antibodies) in PBC

Lymphoma • Secondary lymphoma can also be multinodular or diffusely infiltrative ○ Lymphomatous deposits in liver (and spleen) are usually less discrete • Homogeneous hepatomegaly &/or hypoechoic focal nodules • Mean nodal size is greater in non-Hodgkin lymphoma (NHL) • Nodes tend to be more confluent in NHL, discrete in sarcoidosis

Opportunistic Hepatic Infection • In immunocompromised hosts • Infection by fungi, mycobacteria, viruses, etc. • Heterogeneous hepatosplenomegaly ± abdominal lymphadenopathy • May be indistinguishable by imaging alone

Amyloidosis, Abdominal Manifestations • Heterogeneous hepatomegaly, ± lymphadenopathy 29

Abdominal Manifestations of Systemic Conditions

Sarcoidosis

PATHOLOGY General Features • Etiology ○ Mechanisms that initiate formation of sarcoid granulomas are unknown – Main cause of hepatic granulomas ○ Possible association between sarcoidosis and autoimmune disorders – e.g., primary sclerosis cholangitis, primary biliary cirrhosis • Genetics ○ Several genes appear to confer increased susceptibility to sarcoidosis – HLA-DRB 11, 12, 14, 15, and 17

Gross Pathologic & Surgical Features • Hepatomegaly (18-29%) • Scattered nodular hepatic and splenic lesions (5%)

Microscopic Features • Noncaseating epithelioid granulomas with multinucleated giant cells of Langhans type are scattered throughout liver • Confluent granulomas and fibrosis can be present in cases with severe hepatic involvement • Bile ducts can be damaged and occluded by surrounding fibroinflammatory process

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Overt clinical manifestations are uncommon; usually asymptomatic – Chest symptoms: Cough, dyspnea, chest pain – Malaise, fever, weight loss – Involvement of abdominal organs is frequent in patients with advanced sarcoidosis □ Usually documented after diagnosis of lung involvement ○ Hepatosplenomegaly in about 20% of cases ○ Abdominal ± pelvic lymphadenopathy ○ Advanced disease may cause or simulate cirrhosis – Cirrhosis and focal fibrosis may be caused by ischemia secondary to primary granulomatous phlebitis of portal and hepatic veins – Nodular hyperplasia, biliary obstruction, portal hypertension, Budd-Chiari syndrome may also occur □ Due to occlusion of hepatic ± portal vein branches by fibroinflammatory process □ Portal hypertension may develop without frank cirrhosis □ Granulomatous cholangitis may ductopenia and cholestatic liver injury ○ Hilar adenopathy may obstruct larger bile ducts • Clinical profile ○ Diverse clinical presentations – Classic: Young African American women with chest symptoms 30

○ Lab data: Mild elevation of liver enzymes (4%) – Hypercalcemia, hypercalciuria, hypergammaglobulinemia, anemia, leukopenia – Angiotensin-converting enzyme (ACE) elevated in 60% of patients with sarcoidosis ○ Diagnosis: Liver biopsy specimen showing diffuse noncaseating granulomas; small (< 2 mm ) ○ Fine-needle biopsy of palpable or radiologically visible lesions has been proposed recently as reliable, costeffective method for diagnosis of sarcoidosis

• Generalized or focal low liver density, both on pre- and post-contrast enhancement scans

Demographics • Age ○ 20-40 years old at onset of symptoms • Gender ○ Women predominate 3:1 • Ethnicity ○ African Americans:Caucasians = 14:1 • Epidemiology ○ Prevalence: 10-20:100,000 – 24-79% have liver involvement on biopsy ○ Marked variation in prevalence and severity among different ethnic groups

Treatment • Spontaneous remission in many patients • Corticosteroids, anti-inflammatory agents, and cytotoxic drugs: Prednisone, chloroquine, methotrexate • Follow-up US ± CT show good correlation with improvement in liver enzyme levels after steroid therapy and normalization of liver pattern

DIAGNOSTIC CHECKLIST Consider • Imaging studies depict nodular changes in only ~ 1/3 of affected patients • Abdominal CT findings are uncommon and do not correlate with chest radiographic "stage" ○ Presence of hepatic nodules at imaging is not correlated with advanced pulmonary disease • Important to differentiate sarcoidosis from other causes of hepatic granulomas, such as infectious diseases, in which treatment with corticosteroids could be fatal

Image Interpretation Pearls • Do not assume that heterogeneous hepatomegaly and abdominal lymphadenopathy are always malignant • Keys to diagnosis ○ Compatible clinical and imaging manifestation ○ Exclusion of other diseases with similar manifestations ○ Biopsy proof of noncaseating granulomas

SELECTED REFERENCES 1.

Promteangtrong C et al: The role of positron emission tomographycomputed tomography/magnetic resonance imaging in the management of sarcoidosis patients. Hell J Nucl Med. 17(2):123-35, 2014

Sarcoidosis Abdominal Manifestations of Systemic Conditions

(Left) CT section through the chest of a 47-year-old man with multiorgan sarcoidosis shows mediastinal and hilar lymphadenopathy , including right paratracheal lymphadenopathy. (Right) CT section in the same patient shows bilateral hilar lymphadenopathy , the characteristic distribution of thoracic nodes in sarcoid.

(Left) CT section in the same patient shows 1 of numerous small nodules . (Right) Another CT section in the same patient shows peribronchial nodularity and another nodule.

(Left) CT section in the same patient shows numerous small, hypodense, spherical and wedge-shaped lesions in the liver and spleen . (Right) CT section in the same patient shows wedge-shaped and striated hypodense lesions in the right kidney . The renal involvement in this case is less typical and probably represents tubulointerstitial nephritis, a known but rare feature of sarcoid. A more common renal manifestation of sarcoid is nephrocalcinosis &/or nephrolithiasis.

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Abdominal Manifestations of Systemic Conditions

Sarcoidosis

(Left) Axial CT of a 47-year-old woman with dyspnea and hepatosplenomegaly shows innumerable small, noncalcified pulmonary nodules , especially in a periseptal and peribronchial distribution, as well as hilar lymphadenopathy . These are typical features of thoracic sarcoidosis. (Right) Coronal reformation of the chest CT in the same patient also shows confluent parenchymal fibrosis .

(Left) Abdominal MR in the same patient shows hepatosplenomegaly. Innumerable splenic granulomas are well seen hypointense nodules on T2WI , along with lace-like bands of fibrosis that are bright on T2WI . (Right) T2WI of the same patient shows more of the splenic involvement by sarcoidosis.

(Left) A venous phase enhanced T1WI in the same patient shows innumerable small hypointense granulomas within the liver and spleen . (Right) A delayed phase enhanced T1WI shows the lace-like pattern of hepatic fibrosis as bands of delayed and persistent enhancement of delayed phase T1WI. Hepatic and splenic granulomas are no longer evident. These features, along with lymphadenopathy (better shown on more caudal images), are very similar to those seen in primary biliary cirrhosis.

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Sarcoidosis Abdominal Manifestations of Systemic Conditions

(Left) Axial CECT of a 64-yearold woman with advanced (stage 4) thoracic sarcoidosis and liver disfunction shows a small liver, especially the right lobe, with widened fissures, typical of cirrhosis. Hepatic sarcoid may simulate or cause cirrhosis, as in this case. (Right) Another CT section in the same patient shows more evidence of cirrhosis, including perisplenic varices , along with granulomas in the spleen . Hepatic fibrosis and ductopenia related to sarcoid contribute to liver failure.

(Left) Axial CECT of a 45-yearold woman with palpable lymphadenopathy shows bulky lymphadenopathy throughout the abdomen, including cardiophrenic and upper paraaortic stations. (Right) CT section in the same patient shows bulky lymphadenopathy throughout the abdomen (along with splenomegaly) in a pattern very suggestive of lymphoma. No focal hepatic or splenic granulomas are detected. Biopsy revealed sarcoidosis as the cause of the lymphadenopathy.

(Left) Lower CECT section of the same patient shows lymphadenopathy and splenomegaly in a pattern very suggestive of lymphoma. (Right) CT section in the same patient shows additional lymphadenopathy . Sarcoidosis must be considered in the differential diagnosis for widespread lymphadenopathy and splenomegaly. The diagnosis is based on compatible clinical and imaging findings and the presence of noncaseating granulomas on biopsy.

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Abdominal Manifestations of Systemic Conditions

Systemic Hypotension KEY FACTS

TERMINOLOGY • Imaging findings related to shock or severe hypotension

IMAGING • Shock bowel ○ Bowel wall thickening with intense enhancement of bowel mucosa juxtaposed against submucosal edema ○ Typically involves entirety of small bowel (only rarely involves colon) • Shock pancreas ○ Peripancreatic infiltration, stranding, edema, and fluid ○ Pancreas may be hypoenhancing or hyperenhancing ○ Gland is intact (no fracture plane) • Adrenal and renal enhancement ○ Often show intense and prolonged enhancement ○ Adrenals may be enlarged and may hemorrhage ○ Very prolonged renal nephrograms • Collapsed cava sign ○ IVC and renal veins appear flattened

(Left) CECT in a hypotensive patient after trauma shows diffuse pancreatic swelling and peripancreatic edema , a classic manifestation of systemic hypotension. There is no pancreatic laceration to suggest traumatic pancreatic injury. (Right) Axial CECT in a trauma patient demonstrates marked hyperenhancement of the bowel mucosa and submucosal edema . This appearance is characteristic of shock bowel, seen during or following severe hypotension. There is no traumatic bowel injury present.

(Left) Axial CECT in a patient with multiple injuries from a motor vehicle crash shows marked edema/infiltration of the mesenteric and peripancreatic fat planes, an appearance very difficult to differentiate from acute pancreatitis without a clinical history. (Right) Axial CECT in the same patient shows intense enhancement of the small bowel mucosa and the collapsed cava sign , a flattened appearance of the IVC and renal veins due to hypovolemia. There was no bowel or other abdominal injury in this patient.

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○ Halo sign: Low density extracellular fluid surrounding collapsed intrahepatic IVC • Small aorta ○ SMA and other mesenteric arteries may also appear narrowed (often with abnormally intense enhancement) • Spleen and liver ○ May be hypoperfused and hypoenhancing on CECT

PATHOLOGY • All of these signs are indications of severe hypotension, not necessarily from blood loss or trauma ○ Similar findings reported in sepsis, diabetic ketoacidosis, cardiac arrest, head or spinal injury, etc. ○ Due to stimulation of sympathetic nerves in response to hypotension – Shifts blood away from nonessential organs in order to maintain cardiac output and cerebral perfusion • All signs are rapidly reversible with fluid resuscitation &/or correction of underlying cause

Systemic Hypotension

DIFFERENTIAL DIAGNOSIS

Synonyms

Trauma, Small Bowel

• Shock bowel syndrome, hypoperfusion syndrome, hypovolemic shock complex

• Bowel wall thickening in trauma is usually more focal and higher in attenuation (hematoma) than shock bowel

Definitions

Trauma, Pancreatic

• Imaging findings related to shock or severe hypotension

• Parenchymal disruption or fracture plane may be present • Parenchymal/peripancreatic hematoma, rather than edema

IMAGING General Features • Best diagnostic clue ○ Hypotensive, hemodynamically unstable patient with bowel wall, mesenteric, and peripancreatic edema

Acute Pancreatitis • Indistinguishable from peripancreatic edema in systemic hypotension without clinical history

Trauma, Spleen

Imaging Recommendations

• Usually at least some portion of spleen enhances normally • Intrasplenic or perisplenic hematoma ± active extravasation

• Best imaging tool ○ CECT

Splenic Infarct

CT Findings • CECT ○ Shock bowel – Diffuse bowel wall thickening with intense mucosal enhancement juxtaposed against submucosal and mesenteric edema – Diffusely involves entirety of small bowel □ Only rarely involves colon – Bowel may be distended and fluid filled ○ Shock pancreas – Gland is intact (no fracture plane) – Peripancreatic fat stranding, edema, and fluid – Abnormal pancreatic hypoenhancement or hyperenhancement ○ Adrenal and renal enhancement – Often show intense and prolonged enhancement – Adrenals may be enlarged due to hypotensive crisis and may hemorrhage (usually on right side) – Kidneys may show very prolonged nephrogram indicating shock with acute tubular necrosis – Black kidney sign: Absent enhancement of kidneys after trauma in children ○ Collapsed cava sign – Inferior vena cava (IVC)/renal veins flattened □ Defined as diameter < 9 mm over 3 sections obtained at 1 cm intervals in infrahepatic IVC □ Flattened IVC can be normal variant in elderly – Sign of hypovolemia (too little intraluminal blood) – Halo sign: Low density extracellular fluid surrounding collapsed intrahepatic IVC ○ Spleen and liver – May be hypoperfused and hypoenhancing on CECT – Sign tends to be seen more often in children ○ Small aorta – May also be sign of severe hypovolemia – Seen more often in children than adults – Defined as reduced AP diameter (< 13 mm) at 2 cm above and below origin of renal arteries – Superior mesenteric artery (SMA) and other mesenteric arteries may appear narrowed (often abnormally intense enhancement)

• Usually wedge-shaped (rarely involves entire spleen)

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ All of these signs (with possible exception of collapsed cava and small aorta) are indications of severe hypotension, not necessarily from blood loss or trauma – Similar findings reported in sepsis, diabetic ketoacidosis, cardiac arrest, head or spinal injury, etc. – Due to stimulation of sympathetic nerves in response to hypotension □ Shifts blood away from nonessential organs in order to maintain cardiac output and cerebral perfusion □ Results in visceral ischemia, loss of vascular fluid – Blood pressure/pulse may be normal, and CT findings may be 1st clue of hemodynamic compromise ○ All signs are rapidly reversible with fluid resuscitation &/or correction of underlying cause – e.g., blood transfusion for excessive bleeding, treatment of sepsis or diabetic ketoacidosis – CT findings resolve within 24 hours of stabilization

CLINICAL ISSUES Natural History & Prognosis • If treated promptly, does not typically result in frank ischemic injury of bowel or other end organs • High mortality rate (~ 70%) reflects underlying causes of shock/hemodynamic compromise

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Distinguish signs of hypotension from direct effects of visceral trauma in order to avoid unnecessary surgery

SELECTED REFERENCES 1.

Kwon OY et al: Shock bowel caused by neurogenic shock: computed tomography findings. J Emerg Med. 43(4):e251-3, 2012

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Abdominal Manifestations of Systemic Conditions

Superior Vena Cava Obstruction KEY FACTS

TERMINOLOGY

PATHOLOGY

• Occlusion of superior vena cava (SVC) by extrinsic compression, tumor invasion, or intrinsic thrombus

• > 75% of cases due to malignancy ○ Lung cancer and lymphoma most common causes • Other etiologies ○ Thrombosis due to hypercoagulable state, long-term indwelling SVC catheter, or pacemaker ○ Infectious lymphadenopathy from histoplasmosis, tuberculosis, coccidiomycosis ○ Autoimmune or postradiation mediastinal fibrosis ○ Fibrosing mediastinitis

IMAGING • Identify causes of SVC obstruction ○ Mediastinal mass, tumor, or lymphadenopathy ○ Mediastinal calcification due to TB, histoplasmosis ○ Thrombus in SVC • Imaging findings suggesting SVC obstruction ○ Dilated collateral veins (internal jugular veins, intercostal veins, azygous vein, lateral thoracic, etc.) ○ Opacification of portions of liver parenchyma (usually medial segment, quadrate lobe) through collaterals ○ Hot quadrate sign: Avid enhancement of left medial segment of liver on arterial phase (not seen on venous or delayed phases) due to intra- and perihepatic collaterals

(Left) Coronal CECT in an elderly woman who presented with a puffy face demonstrates obstruction of the superior vena cava (SVC) , with collateral flow through an enlarged azygous vein as well as various mediastinal collateral veins . (Right) Axial CECT in the arterial phase in a patient with malignant SVC occlusion demonstrates a wedge-shaped perfusion abnormality in the left medial segment of the liver (hot quadrate sign) and collateral veins over the surface of the liver.

(Left) Axial CECT in a young woman evaluated for aortic dissection shows nearcomplete occlusion of the SVC with extensive collateral veins over the chest and abdominal walls. (Right) Axial CECT in the same patient shows a segment of dense parenchymal enhancement in the medial segment of the liver due to opacification of liver parenchyma alongside the intra- and perihepatic collaterals . The liver perfusion abnormality was not seen on portal venous phase images (not shown).

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CLINICAL ISSUES • Patients with cerebral edema or airway obstruction (due to stridor) must be treated emergently ○ SVC stent placement ± radiation therapy • Remove catheter and anticoagulation for catheter-related thrombus ± catheter-directed thrombolysis

Superior Vena Cava Obstruction

Synonyms • Superior vena cava (SVC) syndrome

Definitions • Occlusion of SVC by extrinsic compression, tumor invasion, or intrinsic thrombus

IMAGING General Features • Best diagnostic clue ○ Mediastinal lymphadenopathy, masses, or calcifications with non-visualized SVC and multiple venous collaterals

CLINICAL ISSUES Presentation

• Best imaging tool ○ CECT • Protocol advice ○ Multiplanar reformations (including maximum-intensity projection reconstructions) to display venous collaterals

• Most common signs/symptoms ○ Facial/neck/arm swelling, dyspnea, cough ○ Stridor, light headache, confusion, engorged neck veins ○ Symptoms vary based on rapidity of obstruction – Slow occlusions allow collaterals (often asymptomatic) – Malignancies occlude SVC quickly, before collaterals have time to form; patients often very symptomatic

CT Findings

Demographics

• CECT ○ Identify causes of SVC obstruction – Thrombus in SVC – Mediastinal mass, tumor, or lymphadenopathy – Mediastinal calcification due to TB, histoplasmosis ○ Imaging findings suggesting SVC obstruction – Dilated collateral veins (dilated internal jugular veins, intercostal veins, azygous vein, lateral thoracic, etc.) – Hyperperfusion of portions of liver parenchyma (usually medial segment) through collaterals – Hot quadrate sign: Avid enhancement of left medial segment of liver on arterial phase (not on venous phase) due to intra-/perihepatic collaterals

• Age ○ Obstruction in young patients often due to lymphoma • Epidemiology ○ Mediastinal histoplasmosis in midwestern USA

Imaging Recommendations

Nuclear Medicine Findings • Hot quadrate (medial segment of liver) following arm injection of Tc-99m sulfur colloid ○ Due to collateral flow through liver (similar to CT finding)

Radiographic Findings • Radiography ○ Superior mediastinal widening or enlargement of right hilum due to lymphadenopathy or tumor ○ Indwelling SVC catheter

DIFFERENTIAL DIAGNOSIS

Natural History & Prognosis • If untreated, may progress to life-threatening cerebral edema and herniation • If due to malignancy, poor prognosis ○ Average life expectancy with SVC syndrome: 6 months

Treatment • Patients with cerebral edema or airway obstruction (due to stridor) must be treated emergently ○ SVC stent placement ± radiation therapy • Other symptoms may not need emergent treatment ○ Emergent radiation might prevent histologic diagnosis ○ In cases with unknown diagnosis and mild symptoms, stent placement first without radiation • Radiation/chemo depending on sensitivity of tumor • Remove catheter and anticoagulation for catheter-related thrombus ± catheter-directed thrombolysis • Surgical bypass rare in malignant obstruction due to limited life expectancy, but possible for benign causes

DIAGNOSTIC CHECKLIST

Aortic Aneurysm or Dissection

Consider

• May mimic/cause SVC obstruction clinically and on imaging

• Fibrosing mediastinitis, tuberculosis, or other granulomatous infections if calcified lymphadenopathy

Occlusion of Other Central Veins • Subclavian/IJ vein occlusions can produce venous collaterals • Often caused by venous catheters or pacemakers

PATHOLOGY General Features • Etiology ○ > 75% of cases due to malignancy – Lung cancer and lymphoma most common causes

Abdominal Manifestations of Systemic Conditions

○ Other etiologies – Thrombosis due to hypercoagulable state, long-term indwelling SVC catheter, or pacemaker – Infectious lymphadenopathy from histoplasmosis, tuberculosis, coccidiomycosis – Autoimmune or postradiation mediastinal fibrosis – Fibrosing mediastinitis □ Most commonly histoplasmosis or tuberculosis □ Soft tissue infiltration with dense calcifications ○ Venous compression due to thin endothelial wall of SVC

TERMINOLOGY

Image Interpretation Pearls • Coronal MIP reconstructions may help identify collateral veins

SELECTED REFERENCES 1.

Katabathina VS et al: Imaging of oncologic emergencies: what every radiologist should know. Radiographics. 33(6):1533-53, 2013

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Abdominal Manifestations of Systemic Conditions

Vasculitis KEY FACTS

TERMINOLOGY • General term describing group of diseases characterized by inflammation and necrosis of blood vessels • Classified by size of blood vessel involved ○ Large vessel: Takayasu arteritis ○ Medium vessel: Polyarteritis nodosa ○ Small vessel: Henoch-Schönlein purpura, lupus vasculitis, Behçet disease, Wegener granulomatosis

IMAGING • Takayasu arteritis ○ Classically involves aortic arch ○ Wall thickening of vascular segment in acute phase ○ Chronic stenoses with post-stenotic dilatation, aneurysms, occlusions, and collateral vessel formation • Polyarteritis nodosa ○ Involves bifurcations of medium and small sized arteries with branch-point aneurysms ○ Renal and mesenteric vessels most often involved

(Left) Axial CECT in a 21-yearold woman with severe abdominal pain shows wedgeshaped defects in the kidneys representing acute ischemic injury. (Right) Axial CECT in the same patient shows long-segment bowel wall thickening and submucosal edema , findings compatible with enteric ischemia. Rheumatoid vasculitis was subsequently confirmed. Findings that suggest bowel or renal ischemia in a young patient, as in this case, should raise suspicion for vasculitis.

(Left) Sagittal CECT demonstrates diffuse narrowing of the abdominal aorta below the superior mesenteric artery with surrounding soft tissue thickening . (Right) Coronal CECT in the same patient nicely demonstrates the narrowing and thickening of the abdominal aorta extending to involve the common iliac arteries. This is a common appearance for a large vessel vasculitis (giant cell vasculitis) with active inflammation.

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○ Renal infarction and atrophy with striated nephrograms • Henoch-Schönlein purpura ○ GI tract often shows manifestations of ischemia ○ Bowel wall thickening, narrowing, and intussusceptions • Wegener granulomatosis ○ Kidneys are involved in 80% of cases ○ Microaneurysms with renal parenchymal scarring, hemorrhage, and bowel ischemia • Lupus vasculitis ○ At risk for bowel complications/ischemia due to vasculitis and hypercoagulability (antiphospholipid syndrome) • Behçet disease ○ Most often involves distal ileum and closely mimics Crohn disease or malignancy

DIAGNOSTIC CHECKLIST • CT findings that resemble bowel or renal ischemia in a young person should raise concern for vasculitis

Vasculitis

Definitions • General term describing a diverse group of diseases characterized by inflammation/necrosis of blood vessels ○ Classified by size of blood vessel involved into small vessel, medium vessel, and large vessel vasculitis ○ Large vessel: Takayasu arteritis ○ Medium vessel: Polyarteritis nodosa ○ Small vessel: Henoch-Schönlein purpura, lupus vasculitis, Behçet disease, Wegener granulomatosis • Takayasu arteritis: Chronic granulomatous inflammatory vasculitis affecting aorta and its main branches • Polyarteritis nodosa: Fibrinoid necrotizing vasculitis involving small and medium vessels with formation of multiple branch-point aneurysms • Henoch-Schönlein purpura: Hypersensitivity-related acute vasculitis affecting small vessels with deposition of IgAcomplexes in skin, joints, kidneys, and GI tract • Wegener granulomatosis: Granulomatous vasculitis of respiratory tract and kidneys • Lupus vasculitis: Complex autoimmune disease with associated necrotizing vasculitis affecting small vessels • Behçet disease: Necrotizing vasculitis of small vessels affecting multiple organs

IMAGING Imaging Recommendations • Best imaging tool ○ CT angiography: First-line modality (regardless of size of vessel involved) – Allows visualization of vascular abnormalities and extravascular organ involvement ○ Conventional angiography helpful in equivocal cases ○ Duplex ultrasound: Screening test for stenosis of proximal mesenteric/renal arteries based on velocity criteria ○ PET/CT: FDG-avidity of involved vessels and visceral sites

General Features • Best diagnostic clue ○ Takayasu arteritis – Irregularity, stenosis, or inflammatory wall-thickening of aorta or main aortic branches on angiography or CT ○ Polyarteritis nodosa – Multiple aneurysms in renal and mesenteric arteries ○ Henoch-Schönlein purpura – Multifocal bowel wall thickening and luminal narrowing on CT in young patient • Location ○ Takayasu arteritis – Classically involves aortic arch, but also involves remainder of aorta in 32% of cases – Only involves descending thoracic and abdominal aorta in 12% of cases – Can involve any of the main branches of thoracic or abdominal aorta, and also frequently involves pulmonary arteries ○ Polyarteritis nodosa – Most apparent at bifurcations of medium and small sized arteries with branch-point aneurysms

○

○

○

○

– Renal (80-90%) and mesenteric arteries (50-70%) most commonly affected – Other locations: Liver, spleen, and pancreas Henoch-Schönlein purpura – Mesenteric small vessels and GI tract involved in 60% of cases – Skin disease usually 1st manifestation with joints and kidneys also often involved Wegener granulomatosis – Kidneys are involved in 80% of cases – May involve any part of GI tract Lupus vasculitis – Can affect any part of GI tract – Superior mesenteric artery commonly affected Behçet disease – GI involvement seen in 50% of cases – Ileocecal region most commonly affected with esophagus as 2nd most common location

Radiographic Findings

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

• Takayasu arteritis ○ Wall thickening of involved vascular segment in acute phase – Can mimic atherosclerotic disease (particularly in mesenteric vessels), but typically smooth, regular, and encompasses longer segment ○ Chronic involvement results in stenosis, post-stenotic dilatation, aneurysms, occlusions, and collateral vessel formation • Polyarteritis nodosa ○ Aneurysms (due to weakening of arterial wall) usually at bifurcation points – Typically small aneurysms (up to 1 cm) – Renal and mesenteric vessels most often involved, but hepatic, splenic, peripancreatic vessels also possible – Pseudoaneurysm formation in intrarenal arteries (8090%) in almost all cases □ May result in intrarenal, subcapsular, or perinephric hemorrhage ○ Renal infarction and ischemic atrophy with striated nephrograms on CT ○ Retroperitoneal hemorrhage due to ruptured aneurysms • Henoch-Schönlein purpura ○ GI tract commonly involved with signs of ischemia – Multifocal bowel wall thickening, ulceration, and luminal narrowing (with intervening normal caliber bowel) – Intramural bowel hemorrhage not uncommon – Intussusceptions very common in pediatric population (13.6% of patients), especially ileoileal and ileocolic ○ Extensive abdominal inflammation with mesenteric lymphadenopathy, mesenteric stranding, engorged mesenteric vessels, and ascites ○ Renal pelvis suburothelial hemorrhage, renal subcapsular hematoma (rare) • Wegener granulomatosis ○ Microaneurysms with renal scarring, intrarenal/perirenal hemorrhage, and bowel ischemia • Lupus vasculitis ○ At risk for bowel complications/ischemia due to vasculitis and hypercoagulability (antiphospholipid syndrome) 39

Abdominal Manifestations of Systemic Conditions

Vasculitis ○ Bowel findings suggestive of ischemia – Focal or diffuse wall thickening due to either submucosal edema or intramural hemorrhage – Avid mucosal hyperenhancement, engorged mesenteric vessels (comb sign), mesenteric edema, ascites, and mesenteric lymphadenopathy – Pneumatosis intestinales, mesenteric venous gas □ Due to infarction or steroids ○ Hydronephrosis ○ Mesenteric thrombosis common (secondary to hypercoagulability from antiphospholipid syndrome) • Behçet disease ○ Most often involves distal ileum and closely mimics Crohn disease or malignancy ○ Focal small bowel wall thickening can mimic polypoid mass – Mass-like manifestation in small bowel possibly associated with greater risk of complications – Large irregular asymmetric ulcers ○ Variable mesenteric fat stranding (due to microperforation) ○ incidence of GI complications (fistulas, sinus tracts)

PATHOLOGY Staging, Grading, & Classification • Based on type of vessels predominantly involved ○ Large vessel vasculitides: Predominantly affecting aorta and major arterial branches – Takayasu arteritis, giant cell arteritis ○ Medium vessel vasculitides: Predominantly affecting visceral arteries and their branches – Polyarteritis nodosa, Kawasaki disease ○ Small vessel vasculitides: Predominantly affecting arterioles, venules, and capillaries – Wegener granulomatosis, Churg-Strauss disease, microscopic polyangiitis, Henoch-Schönlein purpura, lupus vasculitis, Behçet disease – Rheumatoid arthritis: Patients may develop small and medium vessel vasculitis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Takayasu arteritis – Malaise, fever, weight loss, arthralgia – Abdominal pain, bowel ischemia, GI bleeding ○ Polyarteritis nodosa – Fever, malaise, weight loss, headache, myalgia – Renal failure, hypertension, peripheral neuropathy – Abdominal pain, GI bleeding, perforation – Can be fatal if untreated due to aneurysm rupture ○ Henoch-Schönlein purpura – Petechial rash and purpura (in lower extremities), arthritis (large joints), hematuria – Colicky abdominal pain, intussusceptions – Bowel ischemia, perforation (rare) ○ Wegener granulomatosis – Hematuria, proteinuria, renal failure ○ Behçet disease 40

– Oral and genital aphthous ulcers, uveitis, arthritis – Abdominal pain, peritonitis

Demographics • Age ○ Takayasu arteritis – Young and middle-aged adults ○ Polyarteritis nodosa – Middle-aged and older adults ○ Henoch-Schönlein purpura – Children 3-10 years and young adults – 30% of patients are > age 20 ○ Lupus vasculitis – Young and middle-aged adults ○ Behçet disease – More common in 20-40 year olds • Gender ○ Takayasu arteritis – M:F = 1:10 ○ Polyarteritis nodosa – M:F = 1.5:1 ○ Henoch-Schönlein purpura – M:F = 1.2-1.8:1 ○ Lupus vasculitis – M F in Mediterranean and Middle East – M < < F in northern Europe • Epidemiology ○ Takayasu arteritis – More common in Asians – Prevalence in USA: 1-3 per million ○ PAN – Prevalence: 2-33 per million ○ HSP – Prevalence: 20 in 100,000 children – Less common in African Americans ○ Behçet disease – Much more common in East Asia/Middle East – Prevalence: 1 in 500,000 in USA

Treatment • Steroids ± immunosuppressive drugs, such as cyclophosphamide

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • CT findings that resemble bowel or renal ischemia in young person should raise concern for vasculitis

SELECTED REFERENCES 1.

Muto G et al: Large vessel vasculitis in elderly patients: early diagnosis and steroid-response evaluation with FDG-PET/CT and contrast-enhanced CT. Rheumatol Int. ePub, 2014

Vasculitis Abdominal Manifestations of Systemic Conditions

(Left) Coronal CECT in a young woman shows occlusion of the left common iliac artery with collateral vessels that reconstitute the left femoral artery. The superior mesenteric artery is also completely occluded, with collaterals from an enlarged inferior mesenteric artery . (Right) Sagittal CECT in the same patient demonstrates that the origin of the celiac axis is markedly narrowed , with alternating stenoses and aneurysms of the hepatic artery. These findings were found to be secondary to Takayasu arteritis.

(Left) Coronal volumerendered CECT shows diffuse beading and irregularity of the hepatic artery and its branches. This was found to represent Takayasu arteritis, which more often affects the aortic arch. (Right) Axial CECT demonstrates large aneurysms arising from an intrahepatic branch of the hepatic artery and the origin of a replaced left hepatic artery in a patient with polyarteritis nodosa.

(Left) Axial NECT in a 46-yearold man with sudden bilateral flank pain shows bilateral renal and perirenal hemorrhage (high-attenuation fluid collections) . (Right) Catheter angiography in the same patient shows multiple small renal aneurysms that were the source of the bleeding. The diagnosis of Wegener arteritis was subsequently confirmed. Renal or perirenal hemorrhage is especially characteristic of Wegener vasculitis.

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Abdominal Manifestations of Systemic Conditions

Foreign Bodies KEY FACTS

IMAGING • Ingested foreign bodies ○ Commonly affect children, developmentally challenged or psychiatric patients, and inebriated adults ○ Most ingested foreign bodies traverse GI tract without problem: < 1% cause obstruction or perforation – Elongated or sharp objects may impact at point of intestinal narrowing or sharp angulation ○ Foreign bodies vary in radiopacity and conspicuity on radiography vs. CT ○ For most nonsharp foreign bodies, begin with visual inspection of oropharynx and plain radiographs ○ For sharp objects at risk of complications, start with CT • Inserted foreign bodies ○ Rectum, vagina, and urethra are common sites ○ Objects may be inserted during sexual practice, as a result of an assault, or to hide drugs ○ Perforation of rectosigmoid colon may occur with original insertion or during attempted removal

(Left) Plain film shows the appearance of a standard cylindrical-shaped battery after ingestion. Swallowing batteries is relatively common and can cause bowel perforation or obstruction as the acid in the battery may leak out. (Right) Axial CECT in a patient with a retained surgical sponge demonstrates the characteristic CT appearance of a chronic gossypiboma . Note the wavy, serpiginous pattern within the mass and the welldefined wall.

(Left) Axial T2 MR in the same patient demonstrates the characteristic MR appearance of a gossypiboma , with wavy, high T2 signal and a well-defined T2-hypointense wall. (Right) Transverse grayscale US in the same patient demonstrates a very similar appearance to the MR and CT images, with a welldefined mass and internal alternating bands of hyperand hypoechogenicity. Some of the hyperechoic bands with posterior acoustic shadowing may reflect gas within the mass.

42

• Retained surgical items ○ Most common in abdominal surgery (especially emergent) ○ Most commonly woven cotton surgical sponge – Most have radiopaque stripe interwoven into fabric or as attached strip of cloth – Gossypiboma:Foreign body reaction to cotton fabric of sponge or towel producing inflammatory mass with sponge at center □ Low-density heterogeneous mass with wavy, spongiform pattern and internal linear high density (representing the sponge itself) • Intentionally retained surgical material ○ Oxidized regenerated cellulose (Gelfoam/Surgicel) deliberately left in place after surgery for hemostasis ○ Usually absorbed within 7-14 days ○ Tightly packed, swirled, or linear gas on CT – May be mistaken for abscess but contains very little fluid and never shows air-fluid level

Foreign Bodies

Abbreviations • Foreign body (FB)

Definitions • Ingestion or insertion of potentially injurious foreign objects into any site within body

IMAGING Imaging Recommendations • Best imaging tool ○ Plain radiograph or CT

Ingested Foreign Bodies • Commonly affected patient groups ○ Children (vast majority of foreign body ingestions) – Peak incidence between 6 months and 6 years of age – Often swallow coins, toys, or virtually anything else ○ Developmentally challenged or psychiatric patients – Common items include jewelry, batteries, silverware ○ Prisoners and future prisoners – Razor blades (often covered in radiolucent tape to gain entry to hospital), drug packets ○ Edentulous, elderly, or inebriated adults – May swallow bones, toothpicks (common in martini drinkers), plastic tops of medication bottles, etc. – Food bolus impaction more common in edentulous older patients (often with esophageal pathology) • General principles ○ Most ingested FBs traverse GI tract without problem – < 1% cause obstruction or perforation of GI tract – Need for intervention may be higher with intentional ingestions (surgery required in 12-16%) – Overall mortality rate is very low ○ Distinguish accidental or intentional foreign body ingestion from ingestion of diagnostic devices – pH meter capsule, capsule endoscopy, and migrated biliary/pancreatic duct stents can be confusing without clinical history ○ Elongated or sharp objects may impact at point of intestinal narrowing or sharp angulation – (e.g., pylorus, duodenum, ileocecal valve, site of bowel stricture or adhesion) □ Perforations are most common near ileocecal valve – Long pointed objects (toothpick, needle) may lodge in and perforate appendix or Meckel diverticulum □ Perforation may be incomplete or fail to present with acute symptoms; many are discovered weeks to years later ○ Common ingested foreign bodies and management – Most small objects < 2.5 cm in size (i.e., coins) are likely to pass on their own □ Coins account for > 3/4 of foreign body ingestions in children □ Coins may obstruct in esophagus – Longer objects > 6 cm in length (eating utensils, toothbrushes) are unlikely to traverse duodenum and should be retrieved endoscopically – Ingested disk (e.g., watch) batteries are caustic

□ Should be removed from esophagus or stomach if possible □ Often can retrieve from esophagus with balloontipped rubber catheter, magnet, or endoscope – Sharp pointed objects (chicken/fish bones, paperclips, toothpicks, needles, etc.) have high risk of complications (1/3 of patients) □ Should be endoscopically retrieved if in duodenum or stomach □ Follow-up with radiographs if more distal □ Surgery possible if FB fails to pass or complications – Magnets □ Can cause severe injury if multiple magnets are ingested, trapping bowel loops between 2 magnets' attractive force □ Can lead to bowel wall necrosis, fistulas, bowel obstruction, etc. □ All magnets should be retrieved immediately ○ Foreign bodies vary in radiopacity and conspicuity on radiography vs. CT – Plastic and thin aluminum (e.g., pull tabs from cans) are radiolucent – Chicken and meat bones are opaque – Fish bones are often lucent on plain films, opaque on CT – Glass is always radiopaque, but very small slivers may not be detectable – Coins, except for Italian lira, are opaque – Wood is radiolucent (closer to air than soft tissue density) – Medication pills and capsules are variably opaque □ e.g., iron pills, Pepto-Bismol, phenothiazine, many enteric-coated pills – Cocaine or heroin packets are variably opaque; usually wrapped in condoms or balloons and swallowed or inserted into rectum or vagina □ May be visible as crescent of air density between 2 layers of wrapping surrounding drugs; double condom sign □ May appear as well-defined round objects in bowel (of variable attenuation depending on type of drug) ○ Examine entire GI tract for additional FBs – For most nonsharp foreign bodies, begin with visual inspection of oropharynx and plain radiographs – For sharp objects at high risk of complications, start with CT □ Avoid administering enteric contrast material; coating of bowel with contrast may make subsequent endoscopic retrieval more difficult □ IV contrast administration is preferable to better evaluate potential complications – Many patients are repeat offenders and may have swallowed several objects at different times

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Inserted Foreign Bodies • Any orifice may be involved; rectum, vagina, and urethra are common sites • Objects may be inserted during sexual practice, as a result of an assault, to hide drugs and other illegal paraphernalia, or even sharp objects/weapons in prison setting ○ Majority of foreign bodies do not cause significant injury 43

Abdominal Manifestations of Systemic Conditions

Foreign Bodies

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○ Perforation of rectosigmoid colon may occur with original insertion or during attempted removal – Consider contrast enema for diagnosis of perforation ○ Approach to removal (i.e., manual, endoscopic, surgical) will depend on type of FB, symptoms, perforation, etc. • Some rectal or vaginal FBs are result of prior medical interventions ○ e.g., thermometers, enema tips and covers, suppository wrappers, and medications intended for oral use • Any FB remaining in place within bladder or vagina will become encrusted with mineral salts, becoming progressively larger and more opaque ○ Bladder calculus of unusual shape, or in a child, is likely encrusted FB • Body piercing (labia, penis, etc.) may mimic intraluminal FB

Retained Surgical Items • Occurs in roughly 1/18,000 inpatient surgeries, but more common in abdomen (1/1,000-1,500 laparotomies) ○ Particularly common in setting of emergency surgery ○ May be immediately symptomatic but can persist unnoticed for months or even years • Crucial to distinguish intentional or expected objects from unintended ○ Common intentional devices: Surgical drains, rubber retention sutures, metallic clips for wound closure, hemoclips, or intraarterial, intravenous, and intraintestinal catheters ○ Most common unintentional retained foreign body is woven cotton surgical sponge – Suggested by incorrect sponge count, although sponge counts are notoriously inaccurate ○ Retained needles or surgical instruments – Generally easy to recognize but may be misinterpreted as lying outside of patient • Identification of retained surgical sponges or towels on imaging ○ Most have radiopaque stripe interwoven into fabric or as attached strip of cloth – Identified as curvilinear radiopaque line on radiographs or CT ○ Cotton fabric is invisible on radiographs but seen as swirled gas or soft tissue on CT scans – May recognize folded cloth pattern on CT or MR – T2WI MR especially good at depicting folded or swirled cloth pattern within encapsulated fluid collection ○ Gossypiboma:Foreign body reaction to cotton fabric of sponge or towel left inside patient produces inflammatory mass with sponge at center – Produces variable degree of inflammation, fibrosis, and adhesions to adjacent abdominal structures – May cause fistula between bowel segments or to other viscera – Low-density heterogeneous mass with wavy, spongiform pattern, internal linear high density (representing sponge itself), and well-defined wall □ Rarely calcifications in wall in chronic setting – May be difficult to distinguish from abscess (and foreign body reaction may lead to formation of frank abscess)

Intentionally Retained Surgical Material • Oxidized regenerated cellulose (Gelfoam or Surgicel) ○ Bioabsorbable sterile knitted fabric deliberately left in place within surgical bed at end of procedure to produce hemostasis ○ Upon contact with blood, the fabric induces rapid hemostasis by inducing thrombus formation, and swells into gelatinous mass, trapping air (gas) within its interstices ○ Usually absorbed within 7-14 days ○ Has radiographic and CT appearance of tightly packed, swirled, or linear gas bubbles without much fluid content – Usual appearance of soft tissue density mass surrounding gas collections – May be mistaken for abscess, but contains very little fluid and never shows air-fluid level □ Check operative note or discuss with surgeon: Correlate with surgical placement of oxidized cellulose – Presence of hemostatic sponge does not prevent formation of abscess □ Presence of larger loculated collection of fluid or air-fluid level suggests abscess ○ Ultrasound: Echogenic mass with posterior reverberation artifact (indicating gas content) ± surrounding fluid ○ MR: Low signal on T2 due to predominance of gas over fluid – Unlike abscesses, which demonstrate high T2 signal

DIAGNOSTIC CHECKLIST Consider • Expect to find multiple ingested or inserted FBs: Do not stop searching after locating 1st FB ○ Examine entire neck, chest, abdomen, and pelvis in cases of ingested FBs • Distinguish deliberately placed hemostatic material (e.g., oxidized cellulose) from retained surgical sponge or abscess ○ Call surgeon or read operative note to determine whether Surgicel was used for hemostasis

Image Interpretation Pearls • In postoperative patient when evaluating for retained FB, ensure that entire operative field is included within field of view • Distinguish between "expected" and "unexpected" FBs ○ e.g., feeding tubes, surgical clips vs. needles, drains vs. surgical sponges

Reporting Tips • Immediately call referring clinician or operating room if foreign body is detected or suspected

SELECTED REFERENCES 1.

Guelfguat M et al: Clinical guidelines for imaging and reporting ingested foreign bodies. AJR Am J Roentgenol. 203(1):37-53, 2014

Foreign Bodies Abdominal Manifestations of Systemic Conditions

(Left) Axial CECT in a patient with a long psychiatric history demonstrates a linear metallic foreign body in the small bowel, perforating the small bowel and extending into the abdominal wall. (Right) Coronal volume-rendered CECT better demonstrates that the patient has ingested many different pins and paper clips. The patient had a long history of ingesting pins and had to be taken to surgery to remove the foreign bodies.

(Left) Axial NECT shows portions of a foreign object within the bladder. The object turned out to be a penlight which was subsequently retrieved in the cystoscopy suite. (Right) Frontal radiograph in a patient with rectal pain shows a faintly opaque cylindrical object in the expected position of the rectum. Under general anesthesia the plastic dildo was retrieved.

(Left) Axial CECT in a patient who had unintentionally swallowed a metallic clip demonstrates that the clip has caused an inflammatory stricture of the adjacent small bowel, which is thickened with mucosal hyperemia. (Right) Frontal image from a small bowel follow-through demonstrates a filling defect corresponding to the clip seen on CT. Note that the stricture in the immediately distal small bowel is causing mild obstruction of the dilated proximal bowel.

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Abdominal Manifestations of Systemic Conditions

Foreign Bodies

(Left) Coronal CT scout view demonstrates a wavy radiopaque band in the pelvis, typical of a retained surgical sponge. This radiopaque tag can be directly woven into the sponge or can be attached to it. (Right) Axial CECT in the same patient demonstrates an inflammatory gas and fluidcontaining mass forming around the retained sponge, characteristic of a gossypiboma.

(Left) Axial CECT in an elderly man with pain following aortic bypass surgery shows a large mass, a gossypiboma consisting of swirled gas and soft tissue density, that was found to represent a surgical towel that had been left in the peritoneal cavity. Note the absence of a radiopaque marker. (Right) Axial CECT in a patient who had recently undergone surgery demonstrates a fluid collection with a welldefined wall and multiple foci of internal gas. Notice the radiopaque foreign body within the collection.

(Left) Coronal CECT in the same patient nicely demonstrates the full extent of the bilobed fluid collection , and once again demonstrates the linear, bandlike foreign body within the collection. (Right) Coronal volume-rendered CECT in the same patient demonstrates that the radiopaque foreign body visualized previously was the radiopaque band incorporated into a surgical sponge. Also note the presence of a plastic ring within the abdomen connected to the surgical sponge.

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Foreign Bodies Abdominal Manifestations of Systemic Conditions

(Left) Radiograph in a young man who stabbed himself in the abdomen with a ballpoint pen shows the faint outline of the plastic pen and its metal tip . (Right) Lateral spot film from a small bowel follow-through in the same patient shows a segment of small bowel that is tethered to the anterior abdominal wall with extravasation of barium into a bag overlying the anterior abdominal wall wound. At surgery, small bowel perforation was confirmed, and a plastic Bic pen was retrieved.

(Left) Axial CECT in a patient with abdominal pain and fever after cholecystectomy shows a collection of gas but little fluid in the cholecystectomy bed, mimicking an abscess. Note the adjacent surgical clips . (Right) Axial CECT in the same patient shows the gas collection , which represents retained Surgicel (oxidized cellulose), placed to control continued oozing of blood. It may be impossible to distinguish this from an abscess without the proper history, and in such cases, needle aspiration may be required.

(Left) Axial NECT in a patient with fever and pain following partial left nephrectomy shows a collection of gas and soft tissue density in the perirenal space. This represents Surgicel, not an abscess. Note the surgical clip at the site of resection. (Right) Axial CECT in a patient with a postoperative abscess following partial colectomy shows a collection of gas representing Surgicel , surrounded by a large collection of fluid with an enhancing capsule , typical for an abscess.

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Abdominal Manifestations of Systemic Conditions

Barotrauma KEY FACTS

TERMINOLOGY • Alveolar rupture caused by elevated transalveolar pressure during mechanical ventilation

IMAGING • CT findings ○ Free air in pleural and mediastinal spaces ○ Extraluminal ectopic gas in subcutaneous soft tissues and muscles, lung interstitium, retroperitoneum, intraperitoneal spaces, and bowel wall • Radiographic findings ○ Pneumothorax – Inferiorly displaced costophrenic angle on supine films (deep sulcus sign) ○ Pneumomediastinum – Radiolucent streaks outlining heart and trachea ○ Pneumoperitoneum – Best seen on upright and left decubitus films – Supine films: Air outlining bowel or falciform ligament

(Left) Axial CECT in a young man on a ventilator following a motor vehicle crash shows a tension pneumothorax on the right side and a smaller pneumothorax on the left. Gas dissects under pressure along the peridiaphragmatic fat . (Right) Axial CECT in the same patient shows the extraluminal air from the thorax dissecting into the peritoneal cavity to outline bowel loops. There was no intraabdominal injury.

(Left) Axial CECT in an elderly man on positive pressure ventilation and with known large bilateral pneumothoraces and gas in the mediastinum shows the gas dissecting under pressure into the abdomen, including the retroperitoneum and mesentery . (Right) Axial CECT in the same patient shows that in addition to the extensive retroperitoneal gas, intraperitoneal gas is also present . In some cases, gas can dissect into the bowel wall, simulating pneumatosis from bowel ischemia.

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○ Subcutaneous emphysema – Radiolucent streaks outlining fat and muscles

TOP DIFFERENTIAL DIAGNOSES • Perforated duodenal or gastric ulcer • Iatrogenic introduction of ectopic gas • Other causes of pneumothorax, pneumomediastinum, pneumoperitoneum, or pneumatosis • Ischemic enteritis

PATHOLOGY • Positive pressure ventilation alveolar rupture air leakage into pulmonary interstitium • Interstitial air can dissect along perivascular sheaths into mediastinum • Mediastinal and pleural air can leak into peritoneal and retroperitoneal cavities • Primary risk factors include interstitial lung disease, asthma, acute respiratory distress syndrome (ARDS), and mechanical ventilation with high tidal volumes

Barotrauma

PATHOLOGY

Definitions

General Features

• Alveolar rupture caused by elevated transalveolar pressure during mechanical ventilation

• Etiology ○ Positive pressure ventilation alveolar rupture air leakage into pulmonary interstitium ○ Interstitial air can dissect along perivascular sheaths into mediastinum ○ Mediastinal and pleural air can leak into peritoneal and retroperitoneal cavity ○ Rare complications include tension pneumothorax, bronchopleural fistula, subpleural air cyst, and air embolus

IMAGING General Features • Best diagnostic clue ○ Extraluminal air in patient treated with positive pressure ventilation • Location ○ Ectopic gas in pleural space, mediastinum, subcutaneous soft tissues, intraperitoneal and retroperitoneal spaces, bowel wall

Radiographic Findings • Radiography ○ Diagnosis is difficult because patient is usually supine and being ventilated ○ Pneumothorax – Radiolucent collection of gas between visceral and parietal pleura – Inferiorly displaced costophrenic angle on supine films (deep sulcus sign) ○ Pneumomediastinum – Radiolucent streaks outlining heart and trachea ○ Pneumoperitoneum – Best seen on upright and left decubitus films – Supine films: Air outlining bowel, falciform ligament ○ Subcutaneous emphysema – Radiolucent streaks outlining subcutaneous fat and muscles

CT Findings • Free air in pleural and mediastinal spaces • Free (extraluminal) gas in subcutaneous tissues and muscles, lung interstitium, retroperitoneum and mesentery, intraperitoneal spaces, and bowel wall (pneumatosis)

DIFFERENTIAL DIAGNOSIS Perforated Duodenal or Gastric Ulcer • Gas bubbles and infiltration of fat planes adjacent to duodenal bulb or in lesser sac (gastric ulcer)

Iatrogenic Introduction of Ectopic Gas • Introduction of gas or air via surgery, catheterization, peritoneal lavage, or endoscopy

Other • Multiple other causes of pneumothorax, pneumomediastinum, pneumoperitoneum, or pneumatosis (e.g., pneumoperitoneum due to bowel perforation, pneumothorax due to trauma)

Ischemic Enteritis

Staging, Grading, & Classification • Risk factors ○ Interstitial lung disease; asthma ○ Acute respiratory distress syndrome (ARDS)

CLINICAL ISSUES

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Presentation • Most common signs/symptoms ○ Some patients may be asymptomatic ○ Tachypnea, tachycardia, hypertension or hypotension, oxygen desaturation ○ Abdominal distension, tenderness ○ Subcutaneous emphysema (crepitus on palpation)

Demographics • Epidemiology ○ Older literature reported barotrauma seen in 3% of patients undergoing mechanical ventilation, but frequency has decreased due to low tidal volume ventilation becoming more common

Natural History & Prognosis • Associated with

morbidity and mortality

Treatment • Conservative management ○ Close monitoring of pneumothorax for progression ○ Pneumomediastinum, pneumoperitoneum, and subcutaneous emphysema are self-limited • Chest tube insertion for large pneumothorax • Prevention: Maintaining plateau airway pressure < 30 cm H₂O

DIAGNOSTIC CHECKLIST Consider • Pneumoperitoneum and pneumatosis are rare complications of barotrauma, and abdominal source must be excluded

SELECTED REFERENCES 1.

Santa Cruz R et al: High versus low positive end-expiratory pressure (PEEP) levels for mechanically ventilated adult patients with acute lung injury and acute respiratory distress syndrome. Cochrane Database Syst Rev, 2013

• Pneumatosis can result from ischemia, but also other causes, including medications and barotrauma • Barotrauma is usually accompanied by pneumothorax and other sites of extraluminal air 49

Abdominal Manifestations of Systemic Conditions

Post-Transplant Lymphoproliferative Disorder KEY FACTS

TERMINOLOGY • Heterogeneous group of lymphoproliferative diseases occurring after solid organ or stem cell transplants, ranging from lymphoid hyperplasias to frank malignancies

IMAGING • Can occur anywhere, with abdominal cavity most common ○ Extranodal (80%) > nodal involvement (20%) • Imaging findings of post-transplant lymphoproliferative disorder parallel those of non-Hodgkin lymphoma (NHL) in immunocompetent patients • GI tract: Imaging findings are similar to NHL, including mass-like bowel wall thickening, aneurysmal dilatation, ulcerated polyploid mass, or submucosal nodules • Liver: Most frequently involved abdominal solid organ ○ Single or multiple poorly enhancing masses, discrete mass in porta hepatis, or diffuse infiltration of liver • Spleen: Splenomegaly ± discrete lesions (usually multiple, hypoattenuating, and variable in size)

(Left) Axial CECT in a patient post liver transplant demonstrates a new hypodense mass in the porta hepatis, as well as an enlarging portacaval lymph node . (Right) Axial CECT in the same patient demonstrates extensive retroperitoneal lymphadenopathy . The findings of post-transplant lymphoproliferative disorder (PTLD) in this case are indistinguishable from traditional non-Hodgkin lymphoma (NHL) in an immunocompetent patient.

(Left) Axial NECT demonstrates mass-like wall thickening of a segment of colon with aneurysmal dilatation. (Right) Coronal NECT in the same patient again demonstrates the significant wall thickening of the bowel segment with dilatation. This is a common appearance for both NHL in immunocompetent patients and PTLD.

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• Kidney: Most common site in renal transplant recipients ○ Heterogeneous mass surrounding hilar vessels, parenchymal masses, or diffuse infiltrative disease • Nodal disease: Abdominal nodal involvement in only 1520% of cases ○ Nodal involvement much less common than in immunocompetent NHL

PATHOLOGY • Most cases are related to B-lymphocyte proliferation due to Epstein-Barr virus (EBV) infection

CLINICAL ISSUES • High mortality, with survival rates of only 25-35% • Treatment: Reduction or cessation of immunosuppression can be effective, although antiviral drugs, chemotherapy, or rituximab may be necessary

Post-Transplant Lymphoproliferative Disorder

Abbreviations

•

• Post-transplant lymphoproliferative disorder (PTLD)

Definitions • Heterogeneous group of lymphoproliferative diseases that occur in post-transplant setting (either solid organ or stem cell transplants), ranging from abnormal lymphoid hyperplasias to frank malignancies

IMAGING

•

General Features • Location ○ Extranodal involvement (80%) is much more common than nodal involvement (20%) – Unlike lymphoma in general population where nodal disease predominates ○ Can occur nearly anywhere, with common locations including lungs, GI tract, and CNS – Site of presentation may depend partially on type of transplanted organ – Abdominal cavity is most frequently involved (up to 50% of all cases) – May occur within renal and liver allografts □ Some studies have suggested that PTLD may preferentially affect allograft itself

•

•

Imaging Recommendations • Best imaging tool ○ CECT for initial diagnosis ○ PET/CT for staging and follow-up

CT Findings • Imaging findings of PTLD mostly parallel those of nonHodgkin lymphoma (NHL) in immunocompetent patients • GI tract ○ Small bowel (distal > proximal) > colon > stomach > duodenum > esophagus ○ Imaging findings are similar to NHL in immunocompetent patients – Mass-like wall thickening (most common) with aneurysmal dilatation of lumen – Dominant polyploid mass (often with ulceration) or multiple submucosal nodules – May present with intussusception ○ Unlike lymphoma in general population, there is a markedly increased prevalence of ulceration and perforation of bowel – Spontaneous perforation may be 1st symptom of PTLD • Liver ○ Most frequently involved abdominal solid organ ○ Several possible appearances – Most often single or multiple low attenuation, poorly enhancing masses □ Lesions may vary in size (few mm to few cm) – Diffuse or geographic infiltration of liver with no discrete lesions (liver appears steatotic) – Discrete mass in porta hepatis (sometimes with extension into biliary tree or gallbladder)

•

□ Unique manifestation of PTLD (not common with immunocompetent lymphoma) Spleen ○ Spleen involved in 10-40% of cases (particularly common after liver transplant) ○ Possible appearances – Splenomegaly (most common) ± discrete parenchymal lesions – Parenchymal lesions are typically multiple, lowattenuation, and variable in size ○ Spontaneous rupture is possible complication Kidney ○ Most commonly involved site in renal transplant recipients and may affect native kidneys or allograft ○ Renal allograft involvement – Heterogeneous mass surrounding hilar vessels – Multifocal parenchymal masses ○ Native kidney involvement – Almost always unilateral – Discrete round, hypoenhancing parenchymal lesions – Diffuse infiltrative disease with nephromegaly Adrenal ○ Adrenal involvement in 5% ○ Diffuse infiltration with adrenal enlargement or discrete homogeneous hypoenhancing mass Pancreas ○ Rare manifestation of PTLD only described in pancreatic allograft (not native pancreas) ○ Diffuse enlargement of pancreas mimicking acute pancreatitis ○ Focal hypoenhancing mass in pancreas mimicking pancreatic cancer – No ductal dilatation or pancreatic atrophy Nodal disease ○ Abdominal nodal involvement in only 15-20% – Less common than immunocompetent lymphoma – Nodal involvement is typically seen along with extranodal disease ○ Retroperitoneal nodes > mesenteric nodes ○ Discrete homogeneous enlarged lymph nodes or conglomerate mass of confluent enlarged nodes

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

Fluoroscopic Findings • Luminal ulceration ("target" or bull's-eye lesions) • Aneurysmal dilatation of bowel lumen • Intraluminal polypoid filling defect

Nuclear Medicine Findings • PET/CT ○ May detect disease that is occult on CT (including activity in normal-sized lymph nodes) ○ Useful for follow-up after treatment – Can differentiate viable tumor after treatment from fibrotic tissue without viable tumor ○ Importance of PET/CT partially extrapolated from role in lymphoma in immunocompetent patients ○ May be more effective in diagnosing and staging monomorphic PTLD than polymorphic PTLD

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Abdominal Manifestations of Systemic Conditions

Post-Transplant Lymphoproliferative Disorder

DIFFERENTIAL DIAGNOSIS Recurrent or New Malignancy • Patients with known prior malignancy are at high risk of recurrent malignancy after transplantation ○ e.g., liver transplantation for hepatocellular carcinoma • Previously indolent or undiscovered malignancies may grow rapidly under immunosuppressive therapy ○ Transplant recipients are at markedly increased risk for multiple cancers – Skin and lips (squamous cell carcinomas): Account for ~ 40% of malignancies in transplant recipients – Vulvar, cervical, and uterine cancers – Kaposi sarcoma (6% incidence) – Renal cell carcinoma (in native kidneys or allograft)

Intestinal Opportunistic Infection • May result in bowel wall thickening , but not discrete mass • May result in modest lymphadenopathy

Hepatic and Splenic Opportunistic Infections • Hepatic and splenic microabscesses ○ Usually due to fungal infection, such as candidiasis ○ Multiple small hypodense nodules on CECT may mimic one of the possible appearances of PTLD

PATHOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Some patients are asymptomatic in early stages ○ Fever, night sweats, weight loss, fatigue ○ GI symptoms, allograft dysfunction ○ Laboratory: Markedly elevated EBV viral load, anemia, thrombocytopenia, leukopenia

Demographics • Epidemiology ○ Frequency depends on type of allograft – Multivisceral transplant recipients (13-33%) – Intestinal transplant (7-11%) – Heart-lung transplant (10%) – Lung transplant (2-8%) – Heart transplant (3-4%) – Liver transplant (2%) – Kidney transplant (1%) ○ Highest incidence within 1st year after transplantation (accounts for > 80% of all PTLD cases)

General Features

Natural History & Prognosis

• Etiology ○ Most cases are related to B-lymphocyte proliferation due to Epstein-Barr virus (EBV) infection – Immunosuppression (with T-cell response) results in uncontrolled proliferation of EBV-infected B cells ○ Pathogenesis of EBV negative PTLD is unknown – May account for ~ 30% of all PTLD cases ○ Risk factors – Primary EBV infection – Transplant from seropositive donor to seronegative recipient – Cytomegalovirus infection – Pediatric age group or age > 60 years – Greater degrees of immunosuppression (may be associated with certain drug regimens) □ Greatest risk of PTLD in 1st year after transplant when immunosuppression is highest ○ Can occur in recipients of either – Solid organ allografts – Allogenic hematopoietic stem cell transplantation

• Despite all treatments mortality is still high ○ Survival rates of only 25-35% ○ Mortality highest with monomorphic PTLD

Staging, Grading, & Classification • Hyperplastic (early) lesions ○ Polyclonal proliferation of B-lymphocytes without evidence of frank malignancy ○ Symptoms similar to acute viral infection • Polymorphic lesions ○ Demonstrate evidence of malignant transformation, but do not meet criteria needed to diagnose traditional lymphomas in immunocompetent patients • Monomorphic (lymphomatous) lesions ○ Frank malignancies that can be described using standard nomenclature for lymphoma subtypes 52

– B-cell type (most common) – T-cell type (accounts for 14% of cases) – NK-cell type • Other lymphoproliferative disorders (e.g., Hodgkin)

Treatment • Reduction or cessation of immunosuppression for early polyclonal lesions ○ Return of intact immune system will reject early PTLD as well as allograft in most cases ○ Some patients can be weaned off immunosuppressive therapy without rejection ○ More likely to work with polymorphic PTLD; unlikely to be effective in monomorphic PTLD • Other options ○ Antiviral medication, such as acyclovir (for early polyclonal disease) ○ Chemotherapy (CHOP is most common regimen) ○ Rituximab (monoclonal antibody against CD20 receptor) ○ Localized radiation therapy

DIAGNOSTIC CHECKLIST Consider • Any soft tissue density nodal or visceral mass in transplant recipient should be considered PTLD until proven otherwise

SELECTED REFERENCES 1.

Takehana CS et al: (18)F-FDG PET/CT in the management of patients with post-transplant lymphoproliferative disorder. Nucl Med Commun. 35(3):27681, 2014

Post-Transplant Lymphoproliferative Disorder Abdominal Manifestations of Systemic Conditions

(Left) Axial NECT in a patient with a renal transplant shows large lobulated masses in the left axilla, representing dramatically enlarged left axillary lymph nodes. (Right) Axial NECT in the same patient shows markedly atrophic native kidneys and a right adrenal or retroperitoneal mass , compatible with the patient's PTLD. PTLD can affect essentially any organ or lymph node group in the body, and any soft tissue mass in a transplant recipient must be regarded as worrisome for PTLD.

(Left) Axial NECT in a patient with a renal transplant shows bilateral adrenal masses . (Right) More caudal axial NECT section in the same patient shows the renal allograft in the right iliac fossa . There is massive pelvic lymphadenopathy . Both the lymphadenopathy and the adrenal masses represent manifestations of PTLD.

(Left) Axial CECT in a liver transplant patient shows a large mass within the liver allograft that envelopes the portal vein and bile ducts. The spleen is also involved, with splenomegaly and dozens of small hypodense nodules . (Right) Axial CECT in the same patient shows porta hepatis and portacaval adenopathy present as manifestations of PTLD. Note the biliary stent placed to treat the extrinsic compression of the common bile duct by enlarged nodes and the liver mass.

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Abdominal Manifestations of Systemic Conditions

Leukemia and Lymphoma KEY FACTS

TERMINOLOGY • Heterogeneous group of hematologic malignancies of lymphoid or myeloid origin

IMAGING • Gastrointestinal tract ○ Circumferential wall thickening, large cavitary lesion, polypoid mass, or multiple discrete submucosal nodules • Spleen ○ Diffuse splenomegaly without discrete masses ○ Multiple small hypodense splenic lesions ○ Solitary dominant splenic mass • Liver ○ Solitary mass, multiple masses, or diffuse infiltration • Pancreas ○ Can present as discrete mass or diffuse infiltration ○ No ductal dilatation, glandular atrophy, or biliary obstruction • Kidney

(Left) Coronal CECT in a patient with lymphoma demonstrates massive enlargement of the spleen with innumerable tiny hypodense foci within the splenic parenchyma, in keeping with diffuse splenic lymphomatous involvement. (Right) Axial CECT demonstrates a large mass centered in the spleen extending medially to involve the stomach, which also appears thickened along the greater curvature . These findings were found to be manifestations of nonHodgkin lymphoma (NHL).

(Left) Axial CECT demonstrates diffuse enlargement and infiltration of the pancreas , superficially resembling pancreatitis. (Right) Axial CECT in the same patient demonstrates extensive adenopathy in the mesentery inferior to the pancreas. Notice the manner in which the lymph nodes surround the mesenteric vessels, often described as the sandwich sign. These findings, including the enlargement of the pancreas, were found to represent NHL.

54

○ Solitary dominant mass or bilateral nodules ○ Nephromegaly with diffuse tumor infiltration of kidney ○ Perinephric soft tissue "rind" encasing kidney • Peritoneum and omentum (lymphomatosis) ○ Can be indistinguishable from peritoneal carcinomatosis • Lymph nodes ○ Lymph node enlargement is most common, though nonspecific sign of involvement – Size criteria not reliable and vary by region • Testicles ○ Solitary or multifocal hypoechoic masses on ultrasound ○ Involved sites show increased color flow vascularity

TOP DIFFERENTIAL DIAGNOSES • • • • •

Metastatic lymphadenopathy Sarcoidosis Infections Primary visceral organ malignancies Metastatic disease

Leukemia and Lymphoma

Synonyms • Non-Hodgkin lymphoma (NHL) • Hodgkin lymphoma (HL)/Hodgkin disease

Definitions • Heterogeneous group of hematologic malignancies with lymphoid or myeloid origin

IMAGING

•

Imaging Recommendations • Best imaging tool ○ PET/CT with diagnostic quality contrast-enhanced CT

CT Findings • Gastrointestinal tract ○ Most common extranodal site of NHL (30-40% of cases) – Stomach > small bowel and duodenum > colon (including appendix) > esophagus ○ Mucosa-associated lymphoid tissue (MALT) lymphoma is 2nd most common lymphoma to involve GI tract – Marginal zone B-cell NHL: Low-grade tumor, often poorly detected by CT or PET – Arises from tissue within wall of organ, such as stomach or bowel ○ Lymphoma in any segment of GI tract may share certain patterns – Infiltrative pattern (circumferential wall thickening) □ Aneurysmal dilation of lumen may be due to destruction of myenteric plexus or complete replacement of bowel wall with large ulceration □ Lymphoma is soft lesion and less likely to obstruct bowel than carcinoma or metastases – Ulcerative pattern (often large, cavitated lesions) – Polypoid pattern (with intraluminal mass component) – Nodular pattern (usually multiple submucosal lesions) • Spleen ○ Most common malignant tumor of spleen – Commonly involved in both NHL and HL – Often 1st site of abdominal involvement in HL ○ Multiple possible imaging appearances – Diffuse splenomegaly without discrete mass(es) □ Splenomegaly in lymphoma patient does not necessarily imply lymphomatous involvement – Multiple small hypodense splenic lesions – Solitary dominant splenic mass: Hypodense, hypovascular, ill-defined • Liver ○ Liver involved in ~ 40% of NHL – Extensive regional lymphadenopathy should be clue to diagnosis ○ Can present as solitary mass, multiple masses, or diffuse infiltration of liver – Masses usually hypodense, poorly enhancing, and infiltrative – Liver can be diffusely hypodense (mimicking steatosis) as a result of lymphomatous infiltration • Pancreas

•

•

•

•

○ Can present as a discrete mass (poorly marginated, infiltrative, hypoenhancing) often mistaken for adenocarcinoma – No ductal dilatation or glandular atrophy – Vessels course through mass without narrowing or occlusion ○ Can present as diffuse infiltration and enlargement of gland often mistaken for acute pancreatitis – No peripancreatic fluid or inflammatory change Kidney ○ Several possible imaging patterns of renal lymphoma – Solitary dominant mass: Usually poorly enhancing, infiltrative, homogeneous – Multiple bilateral discrete hypodense masses – Unilateral or bilateral nephromegaly with preserved reniform shape and diffuse infiltration of kidney – Perinephric soft tissue "rind" encasing kidney □ Will often extend inferiorly to encase collecting system and ureter without hydronephrosis – Direct spread of retroperitoneal nodal disease to involve adjacent kidney Adrenal ○ Primary adrenal lymphoma usually presents with bilateral masses; secondary can be unilateral or bilateral ○ Nonspecific infiltrative, hypodense, minimally enhancing, homogeneous mass Peritoneum and omentum (lymphomatosis) ○ Most often seen in patients with aggressive NHL, including Burkitt lymphoma and AIDS-related lymphoma ○ Can be indistinguishable from peritoneal carcinomatosis (soft tissue infiltration of omentum, discrete masses, omental caking, ascites) – Usually greater degree of lymphadenopathy than carcinomatosis should be clue to correct diagnosis – Amount of ascites tends to be less than in carcinomatosis Lymph nodes ○ Lymph node enlargement is most common, though nonspecific sign of involvement – PET/CT shows that "normal size" nodes (< 1.5 cm short axis) commonly harbor tumor, while larger nodes are often due to benign hyperplasia – Nodes in clusters tend to be abnormal – Nodes with fatty hilum are usually normal ○ Hodgkin lymphoma – Usually spreads along contiguous nodal groups ○ Non-Hodgkin lymphoma – Often involves noncontiguous nodal groups and abdominal viscera ○ Lymphadenopathy can be extensive and confluent – Sandwich or hamburger sign: Mesenteric/retroperitoneal conglomerate nodal mass surrounding mesenteric vessels – Vessels may be encased or "stretched" by tumor, but remain patent without narrowing or occlusion Leukemia ○ Can cause findings identical to lymphoma ○ Granulocytic sarcoma (chloroma) – Manifestation of leukemia as soft tissue mass(es) in nodes, viscera, pleural and peritoneal cavities – Most often acute myeloid leukemia (AML)

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

55

Abdominal Manifestations of Systemic Conditions

Leukemia and Lymphoma

Ultrasonographic Findings • Testicles ○ Testes may be sites of silent, residual disease while rest of body has been cleared of cancer ○ NHL is most common tumor of testis in men > 60 years ○ Solitary or multifocal hypoechoic masses on ultrasound – Discrete mass(es) may not be present; diffuse infiltration with abnormal echotexture/echogenicity – Involved sites show increased color flow vascularity – Bilateral in 40% of cases

Nuclear Medicine Findings • PET/CT ○ High sensitivity (90%) and specificity (91%) for PET alone, with PET/CT better than PET or CT alone – PET/CT upstages patients in ~ 30% of NHL and HL cases compared to CT ○ FDG avidity relates to degree of differentiation – Low-grade indolent tumors are often not FDG avid – Higher grade, aggressive tumors show FDG avidity

DIFFERENTIAL DIAGNOSIS Metastatic Lymphadenopathy • Lymphadenopathy in lymphoma tends to be more extensive and confluent; no history of primary malignancy

Sarcoidosis • May mimic lymphoma with hepatosplenomegaly, multiple hypodense nodules in liver/spleen, and lymphadenopathy

Infections • Tuberculosis, HIV, and other infections can cause lymphadenopathy • Opportunistic infections can produce small nodules in liver/spleen

Primary Visceral Organ Malignancies • GI adenocarcinomas show more focal wall thickening and luminal narrowing with frequent obstruction • Extensive lymphadenopathy less common with primary malignancies of GI tract, liver, spleen, pancreas, etc.

Metastatic Disease • No history of primary malignancy in lymphoma patients

PATHOLOGY General Features • Etiology ○ NHL and HL are more common in patients with prior Epstein-Barr viral infection ○ Helicobacter pylori has causative role in gastric MALT lymphoma • Associated abnormalities ○ Immunosuppressed conditions (AIDS, transplantation) – Greatly increase prevalence of NHL

Staging, Grading, & Classification • Primary lymphoma: Involvement confined to single organ ± adjacent lymph node(s) • Secondary lymphoma: Involvement of distant nodes or involvement of > 1 extranodal site 56

• Ann Arbor staging system ○ Stage I: Single lymph node region (I) or localized involvement of single extralymphatic organ or site (IE) ○ Stage II: 2 or more lymph node regions on same side of diaphragm (II) ± localized involvement of single extralymphatic organ (IIE) ○ Stage III: Lymph node regions on both sides of diaphragm (III) ± localized involvement of extralymphatic organ or site (IIIE), spleen (IIIS), or both (IIISE) ○ Stage IV: Disseminated or multifocal involvement of 1 or more extralymphatic sites ± associated lymph node involvement or isolated extralymphatic organ involvement with distant (nonregional) nodal involvement • HL classification ○ Classical (nodular sclerosing, mixed cellularity, lymphocyte rich, lymphocyte depleted) ○ Nodular lymphocyte predominant

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, nausea, vomiting, weight loss, fever, organomegaly, palpable lymphadenopathy ○ Laboratory: Anemia, leukopenia, thrombocytopenia due to bone marrow infiltration or splenic involvement

Demographics • Age ○ Risk for NHL increases with age – Median age: 65 years ○ HL has bimodal peak (20-29 years and > 55 years) • Epidemiology ○ Lymphoma is 5th most common malignancy in USA, accounting for 5% of cancer deaths ○ 88% are NHL and 12% HL ○ Extranodal involvement is more common in NHL (2040%) than in HL (4-5%)

Natural History & Prognosis • HL: Usually curable • NHL: Prognosis depends on type and stage of disease ○ Generally worse prognosis than HL

Treatment • Varies depending on tumor stage, histology, symptoms, performance status, patient's age, and comorbidities ○ Surgery for primary disease limited to single organ; splenectomy for suspected isolated splenic involvement in patient with thoracic HL ○ Radiation therapy, chemotherapy (single-agent or combination therapy), rituximab (monoclonal antibody against CD20), and bone marrow transplant all options depending on type of lymphoma

SELECTED REFERENCES 1.

Cabral FC et al: Peritoneal lymphomatosis: CT and PET/CT findings and how to differentiate between carcinomatosis and sarcomatosis. Cancer Imaging. 13:162-70, 2013

Leukemia and Lymphoma Abdominal Manifestations of Systemic Conditions

(Left) Axial CECT demonstrates a "rind" of hypodense soft tissue encasing both kidneys, a classic appearance of perirenal lymphoma. (Right) Axial CECT demonstrates a large soft tissue mass surrounding the right kidney, representing a manifestation of perirenal NHL.

(Left) Coronal CECT demonstrates mass-like soft tissue thickening of a loop of ileum. Note the lack of bowel obstruction despite significant bowel involvement, a characteristic feature of lymphoma. (Right) Axial CECT in an HIV patient demonstrates a large, ulcerated mass with internal enteric contrast arising from the small bowel. Note the classic aneurysmal dilatation of the involved bowel due to tumor infiltration, a common manifestation of bowel lymphoma.

(Left) Axial CECT demonstrates multiple discrete hypodense masses in the liver, as well as more diffuse hypodense infiltration of much of the remaining liver parenchyma. This was all found to represent lymphomatous infiltration of the liver on biopsy. (Right) Axial CECT demonstrates a large conglomerate nodal mass in the mesentery. Note the encasement of vessels , which course through the mass but remain patent, characteristic of lymphoma.

57

Abdominal Manifestations of Systemic Conditions

Metastatic Melanoma KEY FACTS

TERMINOLOGY • Spectrum of metastatic lesions originating from known or occult malignant melanoma

IMAGING • Unique predisposition for metastatic disease to unusual locations (gallbladder, bowel, spleen, soft tissues, etc.) ○ Most common sites in abdomen: Liver and small bowel • Melanoma metastases are often T1 hyperintense on MR due to melanin content • Lymph nodes ○ 1st nodes to be involved are usually regional lymph nodes with contiguous spread through lymphatic chains ○ Metastatic nodes may enlarge or change in morphology ( enhancement, loss of fatty hilum) • Liver ○ Most common site of visceral organ involvement ○ May be hypervascular on arterial phase and usually hypodense on venous phase

(Left) Axial CECT in a patient with known metastatic melanoma demonstrates mass-like wall thickening and aneurysmal dilatation of 2 segments of colon, in keeping with bowel metastases. (Right) Coronal volumerendered CECT in the same patient demonstrates 3 different metastases , with several others scattered throughout the small and large bowel (not shown). Lymphoma and GI stromal tumors can also cause similar aneurysmal dilatation.

(Left) Axial CECT in a patient with melanoma demonstrates a nodular hypervascular metastasis in the small bowel causing proximal bowel obstruction . (Right) Axial CECT in the same patient demonstrates multiple other sites of nodular enhancing soft tissue in the small bowel. Multifocal metastases to the bowel are not uncommon in melanoma.

58

• Gastrointestinal tract ○ Small bowel most common site (75% of cases) ○ May present as lead point of small bowel intussusception ○ Soft tumor that does not usually cause obstruction • Gallbladder ○ Melanoma is most common metastasis to gallbladder • Kidney ○ Can involve kidney, bladder, or collecting systems ○ Unique predisposition for perirenal space

TOP DIFFERENTIAL DIAGNOSES • • • •

Leukemia and lymphoma Metastases from other primary tumors Primary GI malignancies Kaposi sarcoma

CLINICAL ISSUES • Risk of metastasis correlates with depth of primary tumor into dermis

Metastatic Melanoma

Definitions

•

• Spectrum of metastatic lesions originating from known or occult malignant melanoma

IMAGING General Features • Location ○ Unique predisposition for metastatic disease to unusual locations (gallbladder, small bowel, spleen, subcutaneous soft tissues, etc.) – Can metastasize to nearly any location and may have an isolated metastasis in atypical location – Distant metastases depend on site of primary tumor □ Lower extremity melanomas often spread to pelvis □ Ocular melanomas frequently spread to liver ○ Most common sites of metastases: Skin, lymph nodes (75%), lung (70%), liver (58%), CNS (54%), GI tract (40%) ○ Most common sites in abdomen: Liver and small bowel

Imaging Recommendations • Best imaging tool ○ PET/CT (from vertex through feet) with diagnostic CECT for total body screening

CT Findings • Lymph nodes ○ First nodes to be involved are usually regional lymph nodes with contiguous spread through lymphatic chains – Careful assessment necessary of lymph node stations adjacent to primary tumor – Abdominal nodal involvement in 30% of cases ○ Metastatic nodes may enlarge or change in morphology ( enhancement, loss of fatty hilum, irregular margins) – Involved lymph nodes may enlarge and bleed – Rarely necrotic with peripheral enhancement • Liver ○ Most common site of visceral organ involvement – Particularly common with ocular melanoma, and can occur years after initial diagnosis ○ Single or multiple lesions of variable size ± calcification – May be hypervascular on arterial phase – Most (86%) lesions hypodense on portal venous phase • Gastrointestinal tract ○ Can involve any portion of GI tract, but small bowel is most common site (75% of cases) ○ Can present with a single or multiple lesions, often with central necrosis or ulceration ○ May lead to aneurysmal dilation of bowel lumen ○ May present as lead point of small bowel intussusception ○ Soft tumor that does not usually cause obstruction • Mesenteric involvement ○ Single or multiple nodules of variable size with peritoneal/omental stranding, nodularity, and ascites ○ Melanoma should be considered with large solitary peritoneal soft-tissue mass without known primary • Gallbladder ○ Melanoma is most common metastasis to gallbladder

•

•

•

○ Small, flat, subepithelial nodule gradually progresses to discrete polypoid mass Pancreas ○ Peripancreatic nodes may simulate pancreatic mass ○ Single or multiple enhancing nodules on CECT ○ May be hypervascular on arterial phase and mimic neuroendocrine tumor Spleen ○ Melanoma is common source of metastasis to spleen ○ Multiple ill-defined low-attenuation lesions or welldefined "cystic" lesions (usually with solid component) Kidney ○ Unique predisposition for perirenal space – Large isolated mass in perirenal space should prompt consideration of melanoma – Can involve kidney, bladder, or collecting systems ○ Single or multiple lesions of variable size which can appear solid or "cystic" (never simple cystic appearance) Adrenal ○ Indistinguishable from other metastases on imaging – Usually hypodense, lobulated, and heterogeneous ○ May destroy underlying adrenal gland and result in adrenal insufficiency (Addison syndrome)

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

MR Findings • T1WI ○ Hyperintense to liver (due to melanin content) – Almost unique to melanoma metastases – Amelanotic melanoma may be T1 hypointense – T1WI hyperintensity may occur in other metastases with fat or hemorrhage • T2WI ○ Hyperintense to liver: Similar to other metastases • T1WI C+ ○ May be hyperenhancing on arterial phase imaging ○ Most are maximally conspicuous on portal venous phase

Ultrasonographic Findings • Liver metastases ○ Single or multiple hypoechoic lesions with variable size • Gallbladder metastases ○ Single or multiple masses with broad-based attachment to wall; classically thought to be hyperechoic, but hypoechoic more common ○ Increased vascularity on color Doppler

Fluoroscopic Findings • Upper GI ○ Single or multiple well-defined filling defects in wall of stomach or gut – Bull's-eye or "target" lesion (central umbilication): Mass with barium collection in center ○ May present as submucosal nodules, polypoid mass, or pedunculated intraluminal nodule ○ Usually results in luminal narrowing, but may cause aneurysmal dilation, indistinguishable from lymphoma

Nuclear Medicine Findings • PET/CT ○ FDG avidity in most sites of melanoma ○ Higher accuracy than CT or PET alone 59

Abdominal Manifestations of Systemic Conditions

Metastatic Melanoma

– PET often shows metastases to atypical sites that may be difficult to detect on CT – Used for surveillance of recurrence • Lymphoscintigraphy ○ Injection around primary tumor site in skin with Tc-99mlabeled nanocolloid ○ Allows mapping of pattern of nodal drainage sites that can be sampled at time of initial surgical resection

DIFFERENTIAL DIAGNOSIS Leukemia and Lymphoma • May have widespread lymphadenopathy • Bowel involvement may be identical to melanoma: "Bull'seye" lesions and aneurysmal dilation of lumen

Metastases From Other Primary Tumors • Melanoma may mimic other hypervascular metastases: Hepatocellular carcinoma, neuroendocrine tumor, carcinoid, renal cell carcinoma

Primary GI Malignancies (Small Bowel, Gastric, or Colon Adenocarcinoma) • May appear as annular constricting lesion, but aneurysmal dilatation uncommon • May obstruct bowel (uncommon with melanoma)

Kaposi Sarcoma • Disseminated lymphadenopathy with multifocal hepatic or intestinal nodules (often with "target" lesions) • May appear identical to melanoma, but Kaposi most common in AIDS patients with mucocutaneous lesions

PATHOLOGY General Features • Etiology ○ Originates from melanocytes (derived from neural crest cells during embryonic life) ○ Most melanomas arise from benign skin nevi – Can also arise in eyes or other mucosal surfaces – Primary tumor not identified in ~ 3% of cases which initially present with metastatic disease ○ Exposure to ultraviolet radiation is most important carcinogenic factor • Genetics ○ Multiple gene mutations, including CDKN2A/p16, which accounts for ~ 40% of familial melanomas

Staging, Grading, & Classification • Clinical staging ○ I: Localized melanoma, no metastasis (78%) ○ II: Regional lymph node involvement (18%) ○ III: Distant metastasis (4%) • Breslow staging ○ Thin: Depth < 0.75 mm (46% lead to metastases) ○ Intermediate: Depth 0.76-3.99 mm (50% lead to metastases) ○ Thick: Depth > 4 mm (84% lead to metastases) • AJCC TNM classification ○ T1: 1 mm deep; T2: 1-2 mm deep; T3: 2-4 mm deep; T4: > 4 mm deep 60

○ N0: No node; N1: 1 node involved; N2: 2-3 nodes involved; N3: 4 nodes involved ○ M0: No metastases; M1: Distant metastasis ○ Stage I: T1 or T2a with N0M0; Stage II: T2b-T4b with N0M0; Stage III: N1-N3; Stage IV: Distant metastatic disease (M1)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic or vague abdominal pain ○ Nausea, vomiting, anorexia with GI involvement – Especially with intussusception or obstruction

Demographics • Age ○ Risk increases with age ○ 3rd most common cancer in young adults • Gender ○ Slightly more common in men, who have higher mortality • Epidemiology ○ Melanoma constitutes 1% of all cancers in adults ○ Lifetime risk in USA: 1 in 75 ○ Incidence of melanoma has in past several decades – Secondary to better screening and UV exposure

Natural History & Prognosis • Rate of metastasis correlates with depth of primary tumor into dermis • 5-year survival rate correlates with stage of tumor ○ Clinical staging: Stage I (80%), stage II (45%), and stage III (15%) ○ TNM staging: Stage I (> 90%), stage II (45-77%), stage III (27-70%), and stage IV (< 20%) • Complications include gut perforation and intussusception

Treatment • Resect local primary tumor and sentinel nodes for staging (and for cure if not metastatic) ○ May resect symptomatic metastases to bowel ○ Resection of "limited" nodal or other metastases may offer survival benefit • Combination chemotherapy (dacarbazine, cisplatin, vinblastine, carmustine, tamoxifen) • Growing role for immunotherapy: High-dose interleukin-2 (IL-2), anti-CTLA-4 monoclonal antibodies (ipilimumab), or anti-PD1 monoclonal antibodies (pembrolizumab)

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Check atypical sites for melanoma metastases, including gallbladder, muscles, soft tissues, and bowel • Ocular melanoma has high incidence of liver metastases

SELECTED REFERENCES 1.

Baker JJ et al: Routine restaging PET/CT and detection of initial recurrence in sentinel lymph node positive stage III melanoma. Am J Surg. 207(4):54954, 2014

Metastatic Melanoma Abdominal Manifestations of Systemic Conditions

(Left) Axial CECT demonstrates an avidly enhancing, lobulated, heterogeneous mass in the left adrenal gland in a patient with melanoma treated 10 years ago. Biopsy of the mass found this to be metastatic melanoma. (Right) Axial CECT demonstrates several discrete lobulated, heterogeneous perirenal masses in a patient with melanoma. Metastases from melanoma have a unique predisposition for involving the perirenal space.

(Left) Coronal CECT demonstrates an enhancing mass in the bladder. Notice the additional enhancing lesion in the urethra. Both lesions were found to represent metastatic melanoma. The bladder lesion is indistinguishable from a primary bladder tumor without a clinical history. (Right) Axial CECT shows an enhancing mass in the gallbladder. The patient had a history of melanoma and the lesion had been slowly growing over time. Melanoma is the most common cause of metastases to the gallbladder.

(Left) Axial T1WI MR shows multiple metastases that have the peculiar feature of being hyperintense on T1WI, which is attributed to the melanin in these lesions. In some instances, metastases with fat or hemorrhage can also appear hyperintense on T1WI. (Right) Upper GI series shows classic bull's-eye lesions, consisting of small, intramural masses with central ulceration . Lymphoma and Kaposi sarcoma can also result in bull's-eye lesions.

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Abdominal Manifestations of Systemic Conditions

Kaposi Sarcoma KEY FACTS

TERMINOLOGY • Low-grade malignancy arising from mesenchymal lining of blood and lymphatic vessels that primarily affects skin and mucous membranes

IMAGING • Liver and spleen ○ Multifocal hypodense nodules or masses on CECT with delayed enhancement • Gastrointestinal ○ 50% of patients with cutaneous Kaposi sarcoma (KS) will have GI tract involvement ○ Upper GI tract (especially stomach and duodenum) most common, but can affect any part of GI tract ○ Submucosal nodules or polypoid masses (< 3 cm) most common, although larger infiltrative masses possible ○ Regional enhancing lymphadenopathy common ○ Submucosal nodules on barium studies with ulceration may appear as "target" or bull's-eye lesions

(Left) Axial CECT in a patient with AIDS and disseminated Kaposi sarcoma (KS) shows widespread thoracic lymphadenopathy. Many of the lymph nodes demonstrate hypervascularity , characteristic of KS. (Right) Axial CECT in the same patient shows widespread abdominal lymphadenopathy with hyperenhancing lymph nodes that help to distinguish KS from lymphoma or other causes of lymphadenopathy.

(Left) Axial CECT through the pelvis in an AIDS patient shows widespread avidly enhancing adenopathy . On excisional biopsy, there was histologic evidence of Castleman disease and KS, both of which can present with avidly enhancing lymph nodes. (Right) Axial CECT in a patient with HIV and KS shows widespread lymphadenopathy, including nodes in the groin that show hyperenhancement. This patient complained of marked edema of the lower extremities, a common symptom of KS-induced inguinal lymphadenopathy.

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• Lymphadenopathy ○ Most commonly involves retroperitoneal lymph nodes ○ Commonly hypervascular/avidly enhancing

PATHOLOGY • Associated with human herpesvirus type 8 (HHV8) infection and variable cofactors • 4 clinical subtypes of KS ○ Classic (sporadic) KS: Affects elderly men of Eastern European or Mediterranean origin with visceral involvement uncommon – Indolent cutaneous involvement of lower extremities ○ Endemic (African) KS: Not associated with HIV, and accounts for up to 1/2 of all cancers in parts of Africa ○ Iatrogenic (organ transplant-related) KS: Typically develops 1-2 years after transplant, with visceral involvement more likely with heart and liver transplants ○ Epidemic (AIDS-related) KS: prevalence with antiretroviral therapies

Kaposi Sarcoma

PATHOLOGY

Abbreviations

General Features

• Kaposi sarcoma (KS)

• Etiology ○ Associated with human herpesvirus type 8 (HHV8) infection and variable cofactors ○ 4 clinical subtypes of KS – Classic (sporadic) KS □ Elderly men of Eastern European or Mediterranean origin □ Usually indolent cutaneous involvement of lower extremities □ Visceral involvement rare (~ 10%) – Endemic (African) KS □ Not associated with HIV as risk factor □ Accounts for up to 50% of all cancers in certain parts of Africa □ Localized, indolent, cutaneous disease in > 50% □ Lymphadenopathy ± visceral involvement can be aggressive – Iatrogenic (organ transplant-related) KS □ Mucocutaneous disease in 90%; 40% develop visceral, disseminated disease □ Typically develops 1-2 years after organ transplantation □ Patients with KS after liver and heart transplants more likely to develop visceral disease (~ 50%) than kidney transplants (~ 25%) – Epidemic (AIDS-related) KS □ Prevalence among patients with AIDS is decreasing with use of effective antiretroviral therapies □ Most prevalent among homosexual men □ In patients with cutaneous KS, autopsy often identifies visceral involvement in lymph nodes (> 70%), lung (50%), GI (50%), and liver/spleen (30%)

Definitions • Low-grade malignancy arising from mesenchymal lining of blood and lymphatic vessels that primarily affects skin and mucous membranes

IMAGING General Features • Best diagnostic clue ○ Disseminated hypervascular lymphadenopathy with multifocal hepatic or intestinal nodules in patient with known cutaneous KS

Radiographic Findings • Barium studies of upper or lower gastrointestinal (GI) tract ○ May show thickened folds or submucosal nodules ○ Nodules in bowel may ulcerate, appearing as "target" or bull's-eye lesions

CT Findings • Liver and spleen: Multifocal nodules or masses (few mm to cm) ○ Typically hypodense on CECT, but may show delayed enhancement and be invisible on delayed imaging • GI tract: 50% of patients with cutaneous KS will have GI tract involvement ○ Upper GI tract (especially stomach and duodenum) most common, but can affect any part of GI tract ○ Submucosal nodules or polypoid masses (< 3 cm) most common, although larger infiltrative masses possible – Regional enhancing lymphadenopathy common ○ May ulcerate, intussuscept, or obstruct • Lymphadenopathy: Can involve any or all abdominal and pelvic nodal groups ○ Most commonly involves retroperitoneal lymph nodes ○ Commonly hypervascular/avidly enhancing

Ultrasonographic Findings • Hepatomegaly with multiple hyperechoic nodules (< 1 cm)

DIFFERENTIAL DIAGNOSIS Lymphoma • Can be indistinguishable from KS, although hyperenhancement of nodes or visceral lesions favors KS

Intestinal Opportunistic Infections • May cause thickened folds in stomach and bowel • Discrete large masses or hyperenhancing nodes uncommon with infection

Other Causes of Hypervascular Lymphadenopathy • Hypervascular lymph node metastases • Castleman disease

Other Causes of Multiple Nodules in Liver

Abdominal Manifestations of Systemic Conditions

TERMINOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Purple-brown mucocutaneous spongiform lesions ○ Similar lesions in viscera on endoscopy or gross inspection • Other signs/symptoms ○ Visceral KS rarely causes significant organ dysfunction – Patients usually succumb to opportunistic infection or lymphoma

Natural History & Prognosis • Classic form has good prognosis with resection of tumor • AIDS-related cases usually die from opportunistic infections

Treatment • Radiation and chemotherapy plus antiretroviral therapy (epidemic type) for symptomatic or disfiguring lesions

SELECTED REFERENCES 1.

Restrepo CS et al: Kaposi's sarcoma: imaging overview. Semin Ultrasound CT MR. 32(5):456-69, 2011

• Metastatic disease from other malignancies • Sarcoidosis • Hepatic microabscesses or fungal infection 63

SECTION 2

Peritoneum, Mesentery, and Abdominal Wall

Introduction and Overview Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

66

Infection Abdominal Abscess

72

,QƮDPPDWLRQ Peritonitis Sclerosing Mesenteritis

76 80

Degenerative Ascites Omental Infarct

84 88

External Hernias Inguinal Hernia Femoral Hernia Obturator Hernia Ventral Hernia Spigelian Hernia Lumbar Hernia Umbilical Hernia

92 96 98 100 101 102 103

Internal Hernias Paraduodenal Hernia Transmesenteric Postoperative Hernia Bochdalek Hernia Morgagni Hernia

104 108 112 113

Vascular Disorders Portal Hypertension and Varices

114

Trauma Traumatic Abdominal Wall Hernia Traumatic Diaphragmatic Rupture

118 120

Treatment Related Postoperative State, Abdomen Abdominal Incision and Injection Sites Peritoneal Inclusion Cyst

124 126 130

Benign Neoplasms Lymphangioma (Mesenteric Cyst) Desmoid

132 136

Malignant Neoplasms Abdominal Mesothelioma Peritoneal Metastases Pseudomyxoma Peritonei

140 144 148

Miscellaneous Eventration and Paralysis of the Diaphragm Vicarious Excretion

152 153

Peritoneum, Mesentery, and Abdominal Wall

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

Embryology and Relevant Anatomy The fetal gut is suspended between the anterior and posterior abdominal walls by the ventral and dorsal mesenteries, which separate to enclose the developing alimentary tube. Important viscera develop within the mesentery of the caudal part of the foregut, such as the liver, pancreas, spleen, and biliary tree. The various mesenteries either regress or elongate. The dorsal mesentery lengthens with the progressive elongation of the small intestine. The ventral mesentery resorbs, which allows communication between the right and left sides of the peritoneal cavity in adults.

Most mobile parts of the gut have a mesentery, while the ascending and descending colon and some parts of the duodenum are considered retroperitoneal, as they are covered only on their anterior surfaces. The root of the mesentery attaches to the posterior abdominal wall. Processes that originate in retroperitoneal organs, such as pancreatitis, may involve intraperitoneal organs by easily spreading through the "subperitoneal space" via the mesenteries.

Variations in the complex rotation, fusion, growth, and resorption of mesenteries and the viscera that develop within them result in common variations in peritoneal and retroperitoneal spaces in adults with clinical manifestations, such as internal hernias. All peritoneal recesses potentially communicate, although, adhesions and other pathologic processes may seal off loculated collections of fluid, such as infected or malignant ascites.

Omentum An omentum is a multilayered fold of peritoneum that extends from the stomach to adjacent organs. The lesser omentum joins the lesser curve of the stomach and proximal duodenum to the liver. The hepatogastric and hepatoduodenal ligaments form the lesser omentum and carry or contain the bile duct, portal vein, hepatic artery, and important lymph nodes.

Peritoneal Cavity

The greater omentum is a 4-layered fold of peritoneum that hangs from the greater curve of the stomach like an apron covering the transverse colon and much of the small intestine. The greater omentum contains variable amounts of fat and abundant lymph nodes. It is mobile and can fill gaps between viscera, acting as a barrier to generalized spread of intraperitoneal infection or tumor, hence the nickname "nature's Band-Aid."

The abdominal cavity contains all of the abdominal viscera, both intra- and retroperitoneal, and is not synonymous with the peritoneal cavity. The abdominal cavity is limited by abdominal wall muscles, diaphragm, and pelvic brim. The peritoneal cavity is a potential space within the abdomen that lies between the visceral and parietal peritoneum. It usually contains only a small amount of fluid (for lubrication). The peritoneal cavity is composed mostly of the greater sac (or general peritoneal cavity). The lesser sac (omental bursa) communicates with the greater sac through the epiploic foramen (of Winslow) and is bounded in front by the caudate lobe, stomach, and greater omentum, and in back by the pancreas and left kidney. To the left, the lesser sac is bound by the splenorenal and gastrosplenic ligaments, and on the right by the lesser omentum and epiploic foramen. While the lesser sac is in communication with the rest of the peritoneal cavity, ascites usually does not enter into it readily. Lesser sac fluid collections usually result from a local source (e.g., pancreatitis or perforated gastric ulcer) or from generalized infection or tumor (e.g., infectious or malignant ascites). Peritoneum The peritoneum is a thin serous membrane consisting of a single layer of squamous epithelium (mesothelium). The parietal peritoneum lines the abdominal wall and contains nerves to the adjacent abdominal wall, making it sensitive to pain with sharp localization. Intraabdominal disease processes that result in sharply localized pain or tenderness have generally progressed to perforation or other sources of peritoneal irritation. The visceral peritoneum (serosa) lines the abdominal organs. Its pain receptors are sensitive only to stretching (e.g., from distended bowel) and result in poor localization of the source of pain. Mesentery Each mesentery is a double layer of peritoneum that encloses an organ and connects it to the abdominal wall. These include the small bowel mesentery and the transverse and sigmoid mesocolons. The mesentery is covered on both sides by mesothelium and has a core of loose connective tissue 66

containing fat, lymph nodes, blood vessels, and nerves, which pass to and from viscera.

Ligaments All double-layered folds of peritoneum, other than the mesentery and omentum, are called peritoneal ligaments. Ligaments connect 1 viscus to another (e.g., the splenorenal ligament) or a viscus to the abdominal wall (e.g., the falciform ligament) and contain blood vessels or remnants of fetal vessels. Peritoneal Recesses Recesses are the dependent pouches formed by reflections of peritoneum. Due to their clinical importance, these often are known by eponyms, such as the Morison pouch (posterior subhepatic or hepatorenal fossa) or the pouch of Douglas (rectouterine fossa or recess). Clinical Implications The peritoneal cavity and its various mesenteries and recesses are usually not apparent on imaging studies unless they are distended or outlined by intraperitoneal fluid or air. Peritoneum that is evident on imaging is thickened due to inflammation, infection, or tumor. Nodular thickening is a sign of malignancy (peritoneal carcinomatosis). Peritoneal recesses are common sites for accumulation of peritoneal fluid (ascites), pus, and peritoneal tumor implants.

Abdominal Wall Musculature The muscles of the anterior abdominal wall and their aponeuroses (sheet-like tendons) act as a corset to confine and protect the abdominal viscera. These muscles help to flex and twist the trunk and maintain posture. They increase intraabdominal pressure voluntarily, assisting in defecation, micturition, and childbirth. The rectus sheath is formed by interlacing fibers of the aponeuroses of the oblique and transverse abdominal

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

The muscles of the posterior abdominal wall are the psoas, iliacus, and quadratus lumborum. These help maintain posture, flex and extend the trunk, and flex the thigh. Clinical Implications The rectus and iliopsoas compartments are common sites for spontaneous bleeding in patients with coagulopathy (e.g., heparin therapy). The rectus sheath is incomplete caudally, allowing rectus sheath bleeding to extend into the pelvic extraperitoneal spaces. Obesity and lack of exercise result in atrophy of the abdominal wall muscles. A pannus is a lax abdominal wall with excessive subcutaneous fat that may simulate a ventral hernia on clinical exam and imaging. Hernias may be postsurgical or occur at congenital points of weakness in aponeuroses. For example, a ventral hernia occurs through the linea alba in the midline. A Spigelian hernia occurs lateral to the rectus muscle, below the umbilicus through a defect in the aponeurosis of the internal oblique and transverse abdominal muscles. Lumbar hernias occur at a congenital point of deficiency just above the iliac crest at what is known as the inferior lumbar triangle (of Petit). Abdominal wall hernias often do not come to clinical attention until adulthood when a general weakening and thinning of the musculofascial plane allows abdominal contents to herniate through the congenital defect.

Differential Diagnosis Mesenteric or Omental Mass (Solid) Common • Lymphoma • Lymphadenopathy, mesentery • Peritoneal metastases • Pancreatitis, acute • Diaphragm insertions (mimic) • Mesenteric hematoma Less Common • Mesothelioma • Desmoid • Sclerosing mesenteritis • Tuberculous peritonitis • Carcinoid tumor • Splenosis Rare but Important • Papillary serous carcinoma of mesentery • Small bowel stromal tumor • Sarcoma of mesentery or retroperitoneum • Weber-Christian disease • Inflammatory pseudotumor • Solitary fibrous tumor • Desmoplastic small round cell tumor • Benign mesenchymal tumors • Leukemic peritoneal implants Fat-Containing Lesion, Peritoneal Cavity Common • Sclerosing mesenteritis • Omental infarct • Epiploic appendagitis • Fibrofatty mesenteric proliferation • Intussusception

• Dermoid (mature teratoma) Less Common • Retroperitoneal sarcoma (liposarcoma) • Metastatic malignant teratoma • Cystic fibrosis, pancreas (mimic) • Lipoma, intestine • Lipomatous infiltration, ileocecal valve Mesenteric Lymphadenopathy Common • Lymphoma • Metastases: Colon carcinoma, pancreatic ductal carcinoma, carcinoid tumor, small bowel carcinoma • Appendicitis • Mesenteric adenitis • Crohn disease • Sclerosing mesenteritis • Mononucleosis • Kaposi sarcoma, mycobacterial infection (intestinal) • Sarcoidosis, abdominal signs

Peritoneum, Mesentery, and Abdominal Wall

muscles. The sheath contains the rectus muscles and the superior and inferior epigastric vessels.

Less Common • Ulcerative colitis • Diverticulitis • Scleroderma, intestinal • Mastocytosis • Celiac-sprue, Whipple, or Castleman disease Abdominal Calcifications Common • Gallstones • Urolithiasis • Abdominal incision and injection sites • Pancreatitis, chronic • Arterial calcification and aneurysm • Costal cartilage calcification (mimic) • Uterine leiomyoma (fibroid) • Vas deferens calcification • Splenic and hepatic granulomas • Phleboliths • Calcified mesenteric lymph nodes • Renal cyst • Appendicolith (fecalith) Less Common • Bladder calculi • Prostatic calcifications • Ovarian carcinoma or teratoma • Pseudomyxoma peritonei • Peritonitis • Sclerosing peritonitis • Porcelain gallbladder • Calcinosis syndromes • Hydatid disease • Renal cell carcinoma, multilocular cystic nephroma • Polycystic disease • Calyceal diverticulum • Adrenal cyst: Infection, carcinoma, pheochromocytoma • Tuberculosis: Adrenal &/or renal calcifications • Mesenteric cyst • Metastases and lymphoma, hepatic • Calcified/ossified scar • Mucinous cystic pancreatic tumor • Mucocele of the appendix

67

Peritoneum, Mesentery, and Abdominal Wall

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

Pneumoperitoneum Common • Duodenal or gastric ulcer • Diverticulitis • Intestinal trauma • Iatrogenic injury, postoperative, bowel anastomotic leak • Pneumothorax, atelectasis (subsegmental), cystic lung disease, barotrauma (mimics) • Colonic interposition (mimic) • Subphrenic fat (mimic) Less Common • Perforated colon • Peritonitis • Abdominal abscess • Pneumatosis of intestine • From female genital tract • Small bowel diverticula • Foreign body perforation Hemoperitoneum Common • Splenic, hepatic, intestinal, or mesenteric trauma • Complication of surgery • Coagulopathic hemorrhage • Ruptured ovarian cyst or ectopic pregnancy, HELLP • Bladder trauma (mimic) • Ruptured aneurysm Less Common • Neoplastic hemorrhage: Hepatic adenoma, hepatocellular carcinoma, hepatic metastases and lymphoma • Ruptured spleen: Mononucleosis, lymphoma Misty (Infiltrated) Mesentery Common • Portal hypertension, varices • Acute pancreatitis • Heart or renal failure • Peritonitis • Lymphoma • Sclerosing mesenteritis • Diverticulitis • Crohn disease • Ischemic enteritis • Postsurgical mesenteric infiltration • Carcinoid tumor Less Common • Mesenteric trauma • Vasculitis, small intestine • Radiation enteritis • Peritoneal metastases • Portal or superior mesenteric vein thrombosis • Small bowel transplantation • Mesothelioma • Lymphangiectasia, intestinal • Coagulopathic hemorrhage • Leukemic infiltration, peritoneum High-Attenuation (Hyperdense) Ascites Common • Hemoperitoneum • Splenic, hepatic, intestinal, or mesenteric trauma

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• Ruptured ovarian cyst or ectopic pregnancy, endometriosis • Coagulopathic hemorrhage, HELLP syndrome • Tumor associated: Hepatic adenoma, hepatocellular carcinoma, vascular metastases • Ruptured visceral artery aneurysm • Vicarious excretion • Bladder trauma • Duodenal ulcer, gastric ulcer Less Common • Peritonitis • Pseudomyxoma peritonei Abdominal Wall Mass Common • Hernia (e.g., ventral or umbilical) • Abdominal wall abscess • Sebaceous cyst • Lipoma • Keloid • Hematoma • Paraumbilical varices • Muscle asymmetry • Injection site Less Common • Endometriosis • Calcinosis syndromes • Metastases • Lymphoma and leukemia • Desmoid • Sarcoma Elevated or Deformed Hemidiaphragm Common • Paralyzed diaphragm • Eventration of diaphragm • Hiatal, Bochdalek, Morgagni, or traumatic diaphragmatic hernia • Splenomegaly and hypersplenism, hepatomegaly, abscess • Subpulmonic pleural effusion (mimic) Defect in Abdominal Wall (Hernia) Common • Inguinal, femoral, central, incisional, spigelian, lumbar hernia • Rectus sheath hematoma (mimic) • Inguinal lymphadenopathy (mimic) Less Common • Traumatic abdominal wall hernia • Abdominal wall trauma (mimic) • Cryptorchidism (mimic) • Enterocutaneous fistula (mimic) • Urachal remnant (mimic) • Abdominal wall mass (mimic)

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

Lesser omentum

Gastrosplenic ligament Lesser sac (omental bursa) Splenorenal ligament

Peritoneum, Mesentery, and Abdominal Wall

Greater peritoneal cavity

Transverse colon

Greater omentum

Small bowel (SB) mesentery

Descending colon Ascending colon Left paracolic gutter

(Top) The borders of the lesser sac (omental bursa) include the lesser omentum, which conveys the common bile duct and hepatic and gastric vessels. The left borders include the gastrosplenic ligament (with short gastric vessels) and the splenorenal ligament (with splenic vessels). (Bottom) The paracolic gutters are formed by reflections of peritoneum covering the ascending and descending colon and the lateral abdominal wall. Note the innumerable potential peritoneal recesses lying between the bowel loops and their mesenteric leaves, accounting for the polygonal shape of many interloop or mesenteric fluid collections. The greater omentum covers much of the bowel like an apron.

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Peritoneum, Mesentery, and Abdominal Wall

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall

Hepatogastric ligament Hepatoduodenal ligament Epiploic foramen (of Winslow)

Greater omentum

Liver (caudate lobe) Lesser omentum Lesser sac Stomach

Pancreas Superior mesenteric artery Duodenum (3rd portion)

Gastrocolic ligament

Transverse mesocolon

Transverse colon

Greater omentum

Small bowel mesentery

(Top) The lesser omentum comprises the hepatoduodenal and hepatogastric ligaments and forms part of the anterior wall of the lesser sac. The greater and lesser sacs communicate through the epiploic foramen (of Winslow). (Bottom) Sagittal section of the abdomen shows the peritoneal cavity artificially distended, as with air. Note the margins of the lesser sac in this plane, including caudate lobe of liver, stomach and gastrocolic ligament anteriorly, and pancreas posteriorly. The hepatogastric ligament is part of the lesser omentum and carries the hepatic artery and portal vein to the liver. The mesenteries are multilayered folds of peritoneum that enclose a layer of fat and convey blood vessels, nerves, and lymphatics to the intraperitoneal abdominal viscera. The greater omentum is a 4-layered fold of peritoneum that extends down from the stomach covering much of the colon and small intestine. The layers are generally fused together caudal to the transverse colon. The gastrocolic ligament is part of the greater omentum.

70

Imaging Approach to the Peritoneum, Mesentery, and Abdominal Wall Peritoneum, Mesentery, and Abdominal Wall

(Left) This man has metastatic melanoma. CT shows nodular metastases on the serosal surface of the stomach and ascites. (Right) CT in the same patient shows nodular metastases to the omentum , mesentery , and serosal surface of the small bowel . Note the clustered adherence of the SB segments due to the serosal metastases, often resulting in a functional SB obstruction.

(Left) In this trauma case, CT shows extensive, heterogeneous, clotted blood surrounding the spleen, and lower density, more homogeneous blood in the right subphrenic space . This sentinel clot sign helped to identify the spleen as the source of hemorrhage. (Right) This man has malignant melanoma with acute abdominal pain. CT shows a metastasis to the liver with an adjacent sentinel clot , indicating capsular rupture and bleeding. Lower density hemoperitoneum is also seen .

(Left) This 64-year-old woman has non-Hodgkin lymphoma. CT shows splenomegaly and massive diffuse lymphadenopathy including mesenteric lymphadenopathy "sandwiching" the superior mesenteric vessels. Some of the retroperitoneal nodes are unusually low in density; a finding that can also be seen in tuberculosis and Whipple disease. (Right) Axial CECT illustrates typical features of mesenteritis, including involvement of the jejunal mesentery, cluster of enlarged nodes , thin capsule , and perivascular halo of sparing.

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Abscess KEY FACTS

TERMINOLOGY • Localized abdominal collection of pus or infected fluid

IMAGING • CT: Low density, loculated, encapsulated fluid collection with peripheral rim enhancement ○ Simple fluid density (0-10 HU) or slightly hyperdense ○ Internal gas in absence of intervention/drainage highly suspicious for infected collection ○ "Abscess" suggests a discrete, drainable fluid collection: Differentiate from ill-defined inflammation and fluid that is not drainable (i.e. phlegmon) ○ Adjacent fat stranding, edema, and fascial thickening due to inflammation ○ Intraparenchymal abscess (liver, kidney, etc.) often surrounded by low-density parenchymal edema • US: Complex fluid collection with internal low-level echoes, membranes, or septations

(Left) Axial CECT in an elderly postoperative patient demonstrates a rounded complex fluid collection with gas bubbles and an enhancing capsule , findings diagnostic for an abdominal abscess. (Right) Axial CECT in a elderly postoperative patient demonstrates multiple loculated fluid collections with prominently enhancing capsules and mass effect on adjacent structures, representing abdominal abscesses. Note the air-fluid level within one of the abscesses.

(Left) Axial CECT shows a large pelvic abscess following hysterectomy. Note the presence of a discrete enhancing rim and mass effect on adjacent loops of bowel and the bladder. (Right) Axial CECT shows placement of a percutaneous drainage catheter using a transgluteal approach. The abscess has almost completely resolved following drainage.

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○ Increasing complexity within abscess fluid suggests thicker, more viscous contents ○ Greater complexity on US often implies greater difficulty in drainage (especially with small-caliber catheters) ○ Center of abscess avascular on color Doppler imaging, with peripheral hyperemia

PATHOLOGY • Many different causes including postoperative setting, enteric perforation, generalized bacteremia, and trauma

CLINICAL ISSUES • Increased incidence in diabetics, immunocompromised patients, and postoperative patients

DIAGNOSTIC CHECKLIST • Differentiating abscess from noninfected collections after surgery may be difficult and requires correlation with clinical symptoms of infection or fluid aspiration

Abdominal Abscess

Definitions • Localized abdominal collection of pus or infected fluid

IMAGING General Features • Best diagnostic clue ○ Loculated, encapsulated fluid collection with peripheral rim enhancement ± gas bubbles or air-fluid level on CECT • Location ○ Can occur anywhere within abdominal cavity, including intraperitoneal space, extraperitoneal spaces, or intraparenchymal • Size ○ Highly variable – 2-15 cm in diameter, microabscesses < 2 cm

CT Findings • Low density, loculated, encapsulated fluid collection with peripheral rim enhancement ○ May be simple fluid density (0-10 HU) or slightly hyperdense ○ Often adjacent fat stranding, edema, and fascial thickening due to inflammation ○ Intraparenchymal abscess (liver, kidney, spleen, etc.) often shows surrounding low-density parenchymal edema • Presence of internal gas (~ 50% of cases) in absence of intervention highly suspicious for infected collection • Term "abscess" suggests a discrete, drainable fluid collection: Differentiate from ill-defined inflammation and fluid that is not drainable (i.e., phlegmon) • Can be difficult to distinguish infected from noninfected (e.g., seroma, lymphocele, hematoma) collections

MR Findings • Typically central core of abscess demonstrates fluid signal (low-signal T1WI, high-signal T2WI) ○ Internal complexity may slightly alter signal characteristics (e.g., hemorrhage, proteinaceous content) • Enhancing peripheral rim on T1WI C+ images • Abscesses anywhere in abdomen tend to show restricted diffusion (high signal on DWI with low ADC values) ○ Lower ADC values than noninfected fluid collections – However, lack of restricted diffusion cannot exclude possibility of abscess (overlap in ADC values with necrotic tumors and noninfected collections) • Usually evidence of adjacent soft tissue edema around abscess (high T2 signal)

○ Posterior acoustic through transmission may vary depending on composition of fluid in abscess – Abscesses with thick, viscous, proteinaceous fluid may have relatively little through transmission ○ Center of abscess is typically avascular on color Doppler imaging, with peripheral hyperemia ○ Fat surrounding abscess may appear markedly echogenic due to inflammation – Inflamed fat hyperemic on color Doppler ○ Internal echogenic foci with ring-down artifact and posterior "dirty" acoustic shadowing suggest presence of gas

Radiographic Findings • Radiography ○ Soft tissue "mass" or density ± internal ectopic gas (about 50% of cases) or air-fluid levels – May be associated with loss of soft tissue-fat interface ○ Dilated bowel loops due to focal ileus ○ Subphrenic abscess often results in adjacent pleural effusion and lower lobe atelectasis

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Fluoroscopic Findings • Abscess sinogram ○ Useful after percutaneous drainage to assess presence of residual abscess cavity ○ Defines catheter position and communication with abscess ○ Identifies fistulization of abscess with adjacent bowel, pancreas, or biliary tree

Nuclear Medicine Findings • Ga-67 scan ○ Most often utilized for chronic infections and fever of unknown origin ○ Nonspecific, as Ga-97 may demonstrate uptake with tumors, such as lymphoma, as well as chronic granulomatous processes (i.e., sarcoidosis) • In-111 or Tc-99m-labelled white blood cell (WBC) scan ○ Most often utilized for acute infections or inflammatory bowel disease

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Postoperative Lymphocele • History of lymph node dissection with collection adjacent to surgical clips along lymphatic drainage pathways • Loculated collection of simple fluid attenuation without peripheral enhancement or internal gas

Ultrasonographic Findings

Biloma

• Complex fluid collection with internal low-level echoes, membranes, or septations on US ○ Dependent echoes represent debris within abscess – Increasing complexity within abscess fluid suggests thicker, more viscous contents – Greater complexity on US often implies more difficult drainage (especially with small-caliber catheter)

• Fluid collection adjacent to biliary tree in patient with history of biliary or hepatic surgery • Usually simple fluid attenuation without peripheral enhancement or internal gas (unless superinfected)

Postoperative Seroma • Simple fluid attenuation without peripheral enhancement

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Abscess ○ Microabscesses due to fungal infections in immunocompromised patients

• May be loculated or contain internal gas due to recent surgery

Loculated Ascites

Natural History & Prognosis

• Often in patients with cirrhosis, chronic liver disease, chronic renal failure, or other underlying cause for ascites • Simple fluid attenuation with minimal mass effect, no peripheral enhancement, and no internal gas • May demonstrate complexity (e.g., septations) on US or MR but appear simple on CT

• Variable depending on extent of abscess, patient's immune system status, and other comorbidities • Overall excellent prognosis if treated appropriately

Pancreatic Pseudocyst • Clinical history or imaging stigmata of prior pancreatitis • Location highly variable, but most often within pancreatic parenchyma, lesser sac, anterior pararenal space, or transverse mesocolon • Pseudocyst usually requires several weeks to develop peripheral pseudocapsule

Abdominal Hematoma • Attenuation variable depending on age of blood products, but clot is typically high attenuation (> 45 HU) in the acute setting and gradually decreases in attenuation over time • May demonstrate weak peripheral enhancement as it evolves (without necessarily being infected)

Retained Oxidized Cellulose (Surgicel) • Placed at surgery to induce hemostasis and appears as collection of gas bubbles without much fluid • May mimic abscess, but no discrete fluid collection

PATHOLOGY General Features • Etiology ○ Many different causes including enteric perforation (e.g., perforated appendicitis, diverticulitis), postoperative setting, generalized bacteremia, and trauma – Postoperative abscess may be variably located depending on site of surgery, but most often occurs in intraperitoneal spaces, such as cul-de-sac, Morison pouch, subphrenic spaces • Genetics ○ Risk increased if genetically altered immune response ○ Diabetics have incidence of gas-forming abscesses

CLINICAL ISSUES

Treatment • Options, risks, complications ○ Percutaneous abscess drainage (PAD) – 80% success rate, with patient selection critical for success – Best candidates have well-defined, encapsulated, fluid-filled abscesses > 3 cm with safe catheter access route – Drainage can be performed under CT or US guidance, with multiple approaches possible (transcutaneous, transgluteal, transrectal, transvaginal) – Complex abscess (i.e., multiseptated) or abscess with enteric fistula may take weeks or months to drain, but most abscesses can be drained in 10-14 days – Catheter removed when drainage < 10 cc per shift or when abscess cavity resolves on imaging ○ Contraindications for PAD related to patient coagulopathy (elevated INR or low platelet count) ○ Contraindications for PAD related to abscess – Poorly defined collection (i.e., phlegmon) rather than discrete drainable abscess – No safe access route for catheter insertion due to intervening bowel, adjacent vital organs, or pleura □ Crossing colon is greater risk than traversing small bowel or stomach □ Crossing sterile collections (such as hematoma) or sterile pleural effusion should be avoided due to risk of superinfection – Echinococcal cyst (due to risk of leakage and resultant anaphylaxis) ○ Surgery indications – Extensive intraperitoneal abscesses – Debridement of necrotic infected tissue – Failed percutaneous drainage ○ Small abscesses (usually < 3 cm) may be treated conservatively with antibiotic therapy

DIAGNOSTIC CHECKLIST

Presentation

Consider

• Most common signs/symptoms ○ Fever, chills, abdominal pain ○ Tachycardia and hypotension in setting of sepsis • Clinical profile ○ Leukocytosis, positive blood cultures, elevated ESR ○ Elderly and immunocompromised patients may not have fever or WBC

• Differentiating an abscess from noninfected collections in postoperative setting (e.g., seroma, lymphocele, hematoma) may be difficult and requires correlation with clinical symptoms of infection or fluid aspiration

SELECTED REFERENCES 1.

Demographics • Epidemiology ○ Most commonly in postoperative setting ○ Increased incidence in diabetic and immunocompromised patients

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2.

3.

Elagili F et al: Predictors of postoperative outcomes for patients with diverticular abscess initially treated with percutaneous drainage. Am J Surg. ePub, 2014 Schmid-Tannwald C et al: Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections. Clin Radiol. 69(7):687-94, 2014 Yu H et al: The role of interventional radiology in management of benign and malignant gynecologic diseases. Obstet Gynecol Surv. 68(10):691-701, 2013

Abdominal Abscess Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT in a woman who presented with lower abdominal pain, fever, and tenderness shows extensive free intraperitoneal gas . (Right) Axial CECT in the same patient shows a loculated abscess immediately adjacent to a segment of sigmoid colon with extensive diverticulosis , which proved to be the source of the free air and abscesses.

(Left) Axial CECT in an elderly woman after ERCP and papillotomy shows a large collection of gas and fluid dissecting through the retroperitoneal spaces, especially the anterior pararenal space and the interfascial plane . (Right) Axial CECT in the same patient demonstrates the retroperitoneal abscess. The perforation site was the 2nd portion of the duodenum at the papillotomy site.

(Left) Axial CECT in a young woman with progressive fever and abdominal pain over several days reveals a large periappendiceal abscess with mass effect displacing the small bowel, bladder, and uterus. (Right) Axial CECT in a patient who underwent a cholecystectomy shows a collection of gas , but very little fluid, in the cholecystectomy bed. Surgical clips are also seen. This represents oxidized cellulose (Surgicel), which was placed for hemostasis at surgery, and not an abscess.

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Peritoneum, Mesentery, and Abdominal Wall

Peritonitis KEY FACTS

• Infectious or inflammatory process involving peritoneum or peritoneal cavity

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Ascites ± loculated fluid collections or discrete abscess ○ Ascites may be slightly higher in attenuation (15-30 HU) on CT than simple ascites ○ Internal complexity within ascites fluid (septations, debris) is common and easier to appreciate on MR or US • Smooth thickening and hyperenhancement of peritoneum • Infiltration and fat stranding within mesentery/omentum • Presence of ectopic gas suggests either hollow viscus perforation or gas-forming infection • Other imaging findings may reveal cause of peritonitis (i.e., diverticulitis, appendicitis, low-attenuation nodes in TB) • In chronic setting peritoneal lining may be thickened with smooth, curvilinear calcification

• • • •

(Left) Axial CECT in a cirrhotic patient with spontaneous bacterial peritonitis demonstrates loculated ascites with enhancement and thickening of the parietal and visceral peritoneum . There are bilateral drains in place. (Right) Axial CECT in a patient on chronic peritoneal dialysis with constant symptoms of bowel obstruction shows loculated ascites with thickened, enhancing parietal/visceral peritoneum encasing the small bowel and creating functional obstruction. Note the dilated segments of bowel .

(Left) Axial NECT in a patient with a history of peritoneal dialysis demonstrates extensive calcifications and thickening of the peritoneal lining. (Right) Axial NECT in the same patient demonstrates even more dramatic calcification surrounding bowel loops in the pelvis. These findings are classic for sclerosing peritonitis, most typically seen in patients on chronic peritoneal dialysis.

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○ Most common in sclerosing peritonitis due to chronic peritoneal dialysis: Frequently described as "abdominal cocoon" due to peritoneal thickening and calcification

TERMINOLOGY

Peritoneal carcinomatosis Benign ascites Pseudomyxoma peritonei Hemoperitoneum

PATHOLOGY • Innumerable different causes including spontaneous bacterial peritonitis in cirrhotic patients, bowel perforation, gastrointestinal infections, TB, trauma, surgery, etc. • Peritonitis does not necessarily always imply infection: Sterile peritonitis also possible ○ Sclerosing encapsulating peritonitis: Chronic form of peritoneal inflammation most often due to peritoneal dialysis resulting in severe fibrotic thickening of both visceral and parietal peritoneum

Peritonitis

Definitions • Infectious or inflammatory process involving peritoneum or peritoneal cavity

IMAGING General Features • Best diagnostic clue ○ Ascites and omental/mesenteric fat stranding with symmetric, smooth enhancement and thickening of peritoneal lining • Location ○ Peritoneal surface, mesentery, and omentum • Size ○ May be localized or generalized in peritoneal cavity

CT Findings • Ascites ± loculated fluid collections or discrete abscess ○ Ascites may be slightly higher in attenuation (15-30 Hounsfield units) than simple ascites, but lower in attenuation than hemoperitoneum • Smooth, regular thickening and enhancement of peritoneum (can be either localized adjacent to site of inflammation or generalized throughout abdomen) ○ Smooth peritoneal thickening and enhancement does not always suggest peritonitis – Can be iatrogenic (after surgery or other intervention that irritates peritoneal lining) or appear in earliest stages of carcinomatosis (more commonly nodular and irregular, rather than smooth) • Infiltration and fat stranding within mesentery and omentum (either localized or generalized) • Presence of ectopic gas suggests either hollow viscus perforation or gas-forming infection • Other imaging findings may reveal cause of peritonitis (i.e., diverticulitis, appendicitis, low-attenuation nodes in tuberculous peritonitis) • In chronic setting (usually after multiple bouts of peritonitis) peritoneal lining may be thickened with smooth, curvilinear calcification and encapsulation/tethering of bowel loops ○ Classically seen in sclerosing peritonitis as result of chronic peritoneal dialysis – Extensive peritoneal thickening and calcification may result in frequent small bowel obstructions

MR Findings • Presence of ascites (low signal on T1WI and high signal on T2WI) ○ ± loculated fluid collections or discrete abscesses with peripheral enhancement ○ Septations and complexity within ascites fluid may be present and best appreciated on T2WI • Smooth thickening and enhancement of peritoneal lining on T1WI C+ images ○ May be localized or generalized depending on site and extent of infection/inflammation • Thickening and inflammation of omentum and mesentery (generally high signal on T2WI)

Ultrasonographic Findings • Peritoneal free fluid ± evidence of loculation or complexity (internal septations, debris, hemorrhage, etc.) • Omental and mesenteric fat may appear echogenic and hyperemic on color Doppler US as result of inflammation, particularly adjacent to primary source of infection/inflammation • Ultrasound may be best tool along with MR for diagnosing many pelvic sources of peritonitis ○ i.e., dilated fallopian tube with fluid-debris level (pyosalpinx) or complex adnexal cystic masses (tuboovarian abscesses [TOAs]) in pelvic inflammatory disease (PID)

Radiographic Findings • Radiography ○ Evidence of ascites: > 500 mL required for plain film diagnosis – Flank bulging – Indistinct psoas margin – Small bowel (SB) loops floating centrally – Lateral edge of liver displaced medially (Hellmer sign): Visible in 80% of patients with significant ascites – Pelvic "dog's ear" present in 90% of patients with significant ascites – Medial displacement of cecum and ascending colon present in 90% of patients with significant ascites ○ ± free air (usually in cases with hollow viscus perforation or gas-forming infection)

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Peritoneal Carcinomatosis • Metastatic disease to omentum, peritoneum, or mesentery (most commonly ovarian cancer and gastrointestinal malignancies) • Ascites with nodularity, thickening, and induration of omentum (± discrete mass-like peritoneal implants) ○ Several patterns possible, including micronodular pattern, nodular pattern (more discrete nodules measuring > 5 mm), and omental caking (coalescence of omental metastases into larger conglomerate masses) • Frequently associated with other evidence of metastatic disease and lymphadenopathy • Smooth, regular peritoneal thickening and enhancement on CECT/MR may rarely be present in earliest stages and mimic peritonitis, but more commonly peritoneal lining appears irregular and nodular

Benign Ascites • No evidence of peritoneal thickening, abnormal peritoneal enhancement, or loculation • Clinical history usually different from peritonitis, as patients do not appear acutely ill or have abdominal pain • Multiple different causes of benign ascites ○ Cirrhosis, congestive heart failure (CHF), fluid overload, peritoneal dialysis, chronic renal failure, etc.

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Peritonitis

• Accumulation of gelatinous implants in peritoneal cavity, most commonly due to rupture of mucinous tumor of appendix • Discrete low density implants scallop contour of liver and spleen and displace loops of bowel centrally • Implants may demonstrate calcification • Slowly progressive disorder with relative chronicity of imaging findings (unlike peritonitis)

Hemoperitoneum • High-attenuation intraperitoneal hematoma ○ Free lysed blood (30-45 HU); clotted blood (60 HU) ○ Active arterial extravasation isodense with adjacent major arterial structures • Typically no evidence of peritoneal thickening or enhancement on CECT

PATHOLOGY

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□ Frequently described as "abdominal cocoon" due to peritoneal thickening and calcification □ May more rarely be associated with ventriculoperitoneal shunt catheters and certain drugs □ Frequently results in repetitive bowel obstructions

Pseudomyxoma Peritonei

Gross Pathologic & Surgical Features • Pus in peritoneal cavity • Inflammatory mesenteric changes and adhesions • Hyperemia of adherent omentum or mesentery

Microscopic Features • > 250 leukocytes per mm³ indicates infected ascites

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Fever, abdominal pain, abdominal distension

General Features

Demographics

• Etiology ○ Spontaneous: Secondary bacterial infection of chronic ascites – Most commonly spontaneous bacterial peritonitis (SBP) in setting of cirrhosis and chronic ascites ○ Bacterial infection – Bowel perforation – PID, infected intrauterine device (IUD), ruptured TOA – Gastric or duodenal ulcer – Ruptured appendicitis, ruptured diverticulitis ○ Tuberculous peritonitis: May be associated with other manifestations of abdominal TB ○ Traumatic peritonitis – May result from either frank perforation of bowel or traumatic disruption of peritoneum allowing infection – Most common sites of bowel injury include duodenum, jejunum, distal ileum □ SB injury may present 4-6 weeks post trauma – Colonic injuries are rare but result in more rapid clinical onset of peritonitis ○ Iatrogenic peritonitis – Inadvertent bowel injury or perforation during laparotomy or paracentesis – Postoperative anastomotic leak – Retained foreign body during surgery – Dropped gallstones during laparoscopic cholecystectomy – Infection or chronic sterile inflammation of peritoneum in patients with intraperitoneal dialysis catheters ○ Peritonitis does not necessarily always imply infection: Sterile peritonitis also possible – Sterile peritonitis most commonly iatrogenic, such as foreign body reaction to retained foreign body after surgery or chronic peritoneal inflammation due to peritoneal dialysis catheter – Sclerosing encapsulating peritonitis: Chronic form of peritoneal inflammation most often due to peritoneal dialysis resulting in severe fibrotic thickening of both visceral and parietal peritoneum

• Age ○ Any • Gender ○ No predilection • Epidemiology ○ Increased incidence in patients with chronic ascites (i.e., cirrhosis, peritoneal dialysis)

Natural History & Prognosis • Prompt treatment necessary to avoid sepsis (if underlying cause is infectious) • Prognosis determined by primary etiology ○ Excellent if inflammation is localized without septicemia, but prognosis more guarded with generalized infection

Treatment • Etiology determines treatment, and may include antibiotics or surgery

DIAGNOSTIC CHECKLIST Consider • Differentiate infectious or inflammatory peritonitis from peritoneal carcinomatosis, which may also result in peritoneal thickening and enhancement on CECT • Differentiate imaging findings of peritonitis from benign causes of ascites (cirrhosis, renal failure, etc.)

Image Interpretation Pearls • Smooth thickening and enhancement of peritoneal lining with associated ascites and inflammation of adjacent mesenteric/omental fat

SELECTED REFERENCES 1.

Baker PM et al: Selected topics in peritoneal pathology. Int J Gynecol Pathol. 33(4):393-401, 2014

Peritonitis Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT of TB peritonitis shows ascites, enhancement of the parietal peritoneum , and calcification within a thickened omentum. (Right) Axial CECT in a patient with peritonitis after necrotizing pancreatitis demonstrates large loculated fluid collections with prominent thickening and enhancement of the adjacent peritoneal lining .

(Left) Axial CECT in a patient who presented with alcoholic cirrhosis and abdominal pain demonstrates a nodular liver and splenomegaly with ascites, findings consistent with the patient's diagnosis of cirrhosis. Note the loculated ascites and thickened, enhancing parietal peritoneum . (Right) Axial CECT in the same patient reveals a few foci of ectopic gas within the ascites fluid, a classic imaging finding of bacterial peritonitis.

(Left) Axial NECT in a patient with Crohn disease and bacterial peritonitis shows loculations of ascites throughout the abdomen, including thick-walled collections between bowel loops in the mesentery . The thickened parietal peritoneum is further evidence of an inflammatory or exudative etiology for this process. (Right) Axial NECT in the same patient shows infiltration of the omental and mesenteric fat due to the generalized inflammatory process and peritonitis.

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Sclerosing Mesenteritis KEY FACTS

TERMINOLOGY • Idiopathic inflammatory and fibrotic disorder affecting mesentery of unknown etiology

IMAGING • Acute mesenteritis ○ Misty mesentery: Increased attenuation of mesentery with fat stranding and induration ○ Thin (usually < 3 mm) pseudocapsule encasing inflamed mesentery (tumoral pseudocapsule sign) ○ Cluster of mildly enlarged mesenteric nodes ○ Usually located in left upper quadrant mesentery ○ Mesenteric vessels and nodes have halo of spared fat (fat ring or fat halo sign) • Chronic phase ○ Chronic fibrosis results in discrete fibrotic soft tissue mass with desmoplastic reaction ○ "Stellate" appearance with calcification within mass

(Left) Initial CECT evaluation in an elderly man with abdominal pain shows infiltration of the jejunal mesentery marked by a pseudocapsule . (Right) Axial CECT in the same patient shows clusters of mildly enlarged mesenteric nodes . No diagnosis was made at this time, and the patient was not given treatment.

(Left) The same patient returned for evaluation 5 years later, having had chronic pain intermittently for the entire time without a diagnosis being made. Axial CECT shows a soft tissue mass in the mesentery that encases and narrows the mesenteric vessels. (Right) Axial CECT in a 2nd study of the same patient shows a focus of calcification within the fibrotic mesenteric mass. The infiltrated mesentery and pseudocapsule are still evident. This case illustrates progression of the disease over time.

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○ Encasement of mesenteric vessels (especially portomesenteric veins) with resultant collaterals – Small bowel wall edema and mucosal hyperemia as result of lymphatic/venous obstruction and ischemia ○ Tethering of bowel loops can lead to bowel obstruction

PATHOLOGY • Unknown etiology, but associations with prior surgery, trauma, infection, autoimmune diseases, and malignancies

CLINICAL ISSUES • Acute mesenteritis can be cause of acute abdominal pain • Natural history or frequency of progression to chronic fibrotic phase not well understood ○ Most patients have stable or slowly progressing disease without symptoms • Common complications in chronic phase include bowel obstruction, urinary tract obstruction, and bowel ischemia • Treatment: Immunosuppressive therapy should be attempted initially

Sclerosing Mesenteritis

Synonyms • Retractile mesenteritis, fibrosing mesenteritis, mesenteric panniculitis, mesenteric lipodystrophy, liposclerotic mesenteritis, systemic nodular panniculitis, xanthogranulomatous mesenteritis

Definitions • Idiopathic inflammatory and fibrotic disorder affecting mesentery of unknown etiology

IMAGING General Features • Best diagnostic clue ○ "Misty mesentery" with surrounding pseudocapsule, clustered prominent mesenteric lymph nodes, and halo of spared fat surrounding nodes and vessels • Location ○ Most common site: Root of jejunal mesentery – 90% involve small bowel mesentery and primarily to left of midline (jejunal mesentery) ○ Occasionally: Colon (transverse or rectosigmoid) ○ Rarely: Peripancreatic, omentum, and retroperitoneum • Key concepts ○ Uncommon, benign, inflammatory process involving mesenteric fat ○ Classified histologically into 3 types or stages based on predominant tissue type in mass – Mesenteric panniculitis: Acute inflammation ± fat necrosis > fibrosis – Mesenteric lipodystrophy: Fat necrosis > inflammation or fibrosis – Retractile mesenteritis: Fibrosis/retraction > inflammation or fat necrosis ○ Retractile mesenteritis – Considered as final, chronic form, with collagen deposition, fat necrosis, fibrosis, and tissue retraction ○ Often associated with other idiopathic inflammatory disorders (> 1 condition may be present) ○ May coexist with malignancy (e.g., lymphoma, breast, lung, colon cancer, and melanoma)

CT Findings • Acute mesenteritis (mesenteric panniculitis and lipodystrophy) ○ Often associated with misty mesentery: Increased attenuation of mesentery with fat stranding and induration – Nonspecific finding that can be seen with other etiologies – Usually located in left upper quadrant mesentery – Often discrete fat-attenuation "mass" with increasing soft tissue component as disease progresses ○ Thin (usually < 3 mm) pseudocapsule encasing inflamed portion of mesentery (tumoral pseudocapsule sign) ○ Cluster of mesenteric nodes (only rarely enlarged > 1 cm) within misty mesentery – Mesenteric vessels and nodes have halo of surrounding spared fat (fat ring or fat halo sign) • Chronic phase (retractile mesenteritis)

○ Chronic fibrosis results in discrete fibrotic soft tissue mass with desmoplastic reaction – Mass often has "stellate" appearance with internal calcification (and within adjacent lymph nodes) □ Can rarely show internal cystic or necrotic components – Encasement of mesenteric and collateral vessels with frequent narrowing/occlusion of portomesenteric veins □ Collaterals or engorged vessels may be present □ Small bowel wall edema and mucosal hyperemia as result of lymphatic/venous obstruction and ischemia – Tethering of bowel loops can lead to bowel obstruction

MR Findings • Variable signal intensity due to varying elements of inflammation, fat necrosis, calcification, and fibrosis • Acute mesenteritis (panniculitis and lipodystrophy) ○ T1WI: Mixed signal intensity ○ T2WI: Mixed signal intensity (usually mildly hyperintense) • Chronic phase (retractile mesenteritis): Imaging findings of mature fibrotic reaction ○ T1WI: Decreased signal intensity ○ T2WI: Very low signal intensity

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Nuclear Medicine Findings • Mesenteritis usually not FDG avid (unlike malignancy), although multiple reports suggests mesenteritis can be FDG avid

Radiographic Findings • Fluoroscopic-guided barium study ○ Dilation, fixed narrowing, and tethering of jejunum with fold thickening and luminal narrowing in advanced cases

DIFFERENTIAL DIAGNOSIS Retroperitoneal and Mesenteric Lymphoma • Early-stage lymphoma appears identical to mesenteritis with misty mesentery, mildly enlarged nodes, and rarely, fat halo sign • Large discrete/confluent lymph nodes in advanced cases ○ Calcification within lymph nodes very uncommon prior to treatment, but can be seen with treated lymphoma • Treated mesenteric lymphoma can look identical to mesenteritis (with chronic misty mesentery) • Lack of fat halo and lymphadenopathy outside of mesentery favors lymphoma

Carcinoid Tumor • Can appear identical to retractile mesenteritis, with calcified mesenteric mass, desmoplastic reaction, occlusion of vessels, and bowel obstruction • Usually involves ileal mesentery in right lower quadrant • May be associated with hypervascular primary tumor (usually in ileum) and liver metastases

Mesenteric Edema • Fluid infiltrates mesentery and increases attenuation of mesenteric fat, simulating acute mesenteritis 81

Peritoneum, Mesentery, and Abdominal Wall

Sclerosing Mesenteritis

• Misty mesentery can be seen in multiple other conditions, such as cirrhosis, heart failure, portal or mesenteric vein thrombosis, vasculitis, acute pancreatitis, and other abdominal inflammatory conditions

Desmoid Tumor (Fibromatosis) • Benign proliferation of fibrous tissue that usually presents as discrete solid mass (isodense to muscle) • Displaces but does not usually encase mesenteric vessels • Associated with Gardner syndrome or prior surgery

Carcinomatosis (Mesenteric Metastases) • Dominant tumor implant in left upper quadrant mesentery can mimic retractile mesenteritis • Additional implants usually found elsewhere, such as omentum, surface of liver, spleen, or bowel • Carcinomatosis is more frequently associated with ascites

Liposarcoma • Mass with varying soft tissue and fat components (depending on degree of tumor differentiation) and discrete surrounding capsule • More likely to present with mass effect on adjacent structures than mesenteritis

Primary Visceral Malignancy • Can mimic primary malignancy when mesenteritis abuts a visceral organ (such as bowel or pancreas) • Can resemble pancreatic cancer when it occurs near or within pancreatic parenchyma

PATHOLOGY General Features • Etiology ○ Exact etiology remains unknown ○ Several different theories have been suggested – Prior abdominal surgery or trauma – Possible associations with autoimmune disease, infections, and ischemic insults – Possible result of paraneoplastic syndrome □ Possible association with underlying malignancy (particularly lymphoma) in 1-70% of patients • Associated abnormalities ○ Reported association with different idiopathic or IgG4related inflammatory and fibrotic disorders – Retroperitoneal fibrosis, sclerosing cholangitis, Riedel thyroiditis, orbital pseudotumor, and autoimmune pancreatitis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Often incidental finding in asymptomatic patient ○ Abdominal pain (most common symptom), fever, nausea, vomiting, weight loss, and palpable mass • Other signs/symptoms ○ Lab data: Elevated ESR and C-reactive protein may be used to gauge response to therapy ○ Diagnosis: Usually presumptive diagnosis in acute phase based on imaging and elevated inflammatory markers 82

– Percutaneous or surgical excisional biopsy often required for diagnosis in chronic phase

Demographics • Age ○ 2nd-8th decades of life; average age: 60-70 years ○ Very rare in pediatric age group • Gender ○ M:F = 2:1 • Epidemiology ○ Mayo Clinic reports ~ 5 cases per year (pathologically proven) ○ Seems much more commonly recognized on CT (perhaps up to 0.6% of all patients undergoing abdominal CT) ○ Disease is probably underreported and underdiagnosed, as few patients go on to biopsy or specific treatment

Natural History & Prognosis • Natural history not clearly understood due to rarity of disorder and lack of follow-up in many patients ○ Frequency of progression from acute mesenteritis to chronic stage is unknown ○ Most patients have stable or slowly progressing disease without symptoms • Complications most common in chronic setting ○ Bowel or urinary tract obstruction ○ Ischemia due to occlusion of mesenteric vasculature ○ Questionable risk of developing malignancy • Prognosis ○ Partial or complete resolution in some cases (with some patients spontaneously resolving) ○ Most will respond to medical therapy ○ Some progress to bowel obstruction/ischemia and death

Treatment • Immunosuppressive therapy should be attempted initially ○ Tamoxifen + prednisone is first-line regimen – Most effective before fibrotic change ○ Other options include cyclophosphamide, thalidomide, colchicine, and progesterone • Relatively limited role for surgery ○ Surgical excision very difficult in advanced cases due to vascular involvement ○ Surgery may be palliative, such as bypass to relieve bowel obstruction ○ Questionable role for radiation therapy

DIAGNOSTIC CHECKLIST Consider • Differentiate sclerosing mesenteritis from other more common mimics, including other idiopathic inflammatory disorders and malignancies

SELECTED REFERENCES 1.

McLaughlin PD et al: The "misty mesentery": mesenteric panniculitis and its mimics. AJR Am J Roentgenol. 200(2):W116-23, 2013

Sclerosing Mesenteritis Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT in a patient with pain and fever shows infiltration of the jejunal mesentery, demarcated by a pseudocapsule . Multiple prominent mesenteric nodes are present with a fat halo. PET showed no increased activity, and symptoms improved with steroids. (Right) Axial NECT in a patient with chronic pain shows infiltration of the jejunal mesentery with a pseudocapsule . The mesenteric vessels are encased but not obstructed. This was found to represent sclerosing mesenteritis.

(Left) Axial CECT shows an infiltrative mesenteric mass that encases blood vessels. Note the engorgement of the mesenteric veins. This was found to represent sclerosing mesenteritis. (Right) Axial CECT in an elderly woman with chronic pain and diarrhea shows a soft tissue mass at the base of the small bowel mesentery, encasing and narrowing the mesenteric vessels . This was found to represent fibrosing mesenteritis at biopsy.

(Left) Axial CECT demonstrates a calcified mass in the left upper quadrant mesentery with tethering of surrounding bowel loops. (Right) Coronal CECT in the same patient demonstrates the calcified mass . Note the venous collaterals due to obstruction of the superior mesenteric vein, as well as diffuse small bowel wall thickening due to venous/lymphatic obstruction. This was biopsy-proven retractile mesenteritis.

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Ascites KEY FACTS

TERMINOLOGY • Pathologic accumulation of fluid within peritoneal cavity

IMAGING • Transudative ascites: Usually has density of 0-15 Hounsfield units (HU) on CT and appears free flowing ○ Free-flowing ascites conforms to shape of surrounding structures and flows to dependent recesses ○ Simple fluid signal on T1WI (hypointense) and T2WI (hyperintense) MR ○ No appreciable complexity within ascites fluid • Exudative ascites: Typically demonstrates increasing density of fluid with increasing protein content ○ Often mildly hyperdense (15-30 HU) relative to transudative ascites ○ May demonstrate complexity, including septations, peritoneal thickening/enhancement, and loculation ○ Loculated ascites fluid exerts mass effect and displaces adjacent structures (such as bowel loops)

(Left) Axial CECT shows ascites due to hepatic cirrhosis, with large varices and splenomegaly. Notice the relatively simple, uncomplicated appearance of this transudative ascites. (Right) Axial CECT shows massive ascites due to right heart failure. Like other forms of transudative ascites, note that the fluid appears simple without evidence of complexity, nodularity, or adjacent peritoneal thickening/enhancement.

(Left) Ultrasound shows large anechoic ascites in the lower abdomen displacing bowel loops in a patient with cirrhosis. As in this case, simple transudative ascites is classically anechoic, freely mobile, and shows acoustic enhancement. (Right) Ultrasound shows complicated ascites in a cirrhotic patient. The fluid was nonmobile and loculated on realtime scanning, and there are multiple internal septations , suggesting this is not simple transudative ascites. The ascites fluid was found to be infected.

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○ Usually simple fluid signal on T1WI and T2WI MR, but internal complexity and protein can result in intermediate T1 and T2 signal ○ Chylous ascites can measure < 0 HU or demonstrate fatfluid levels

PATHOLOGY • Ascites is typically divided into 2 types ○ Transudative ascites is caused by high portal venous pressures and is characterized by low protein, low LDH, normal glucose, and low specific gravity – Transudative ascites is simple ascites fluid most often caused by cirrhosis, hepatitis, heart failure, renal failure, hypoproteinemia, etc. ○ Exudative ascites is characterized by high protein and high specific gravity – Exudative ascites related to multiple causes, such as infection, ischemia, peritoneal carcinomatosis, peritonitis, or pancreatitis

Ascites

Definitions • Pathologic accumulation of fluid within peritoneal cavity

IMAGING General Features • Location ○ Free-flowing ascites fluid flows to most dependent recesses of abdomen and pelvis – Morison pouch (hepatorenal fossa): Most dependent recess in upper abdomen – Rectouterine or rectovesical space: Most dependent spaces in pelvis – Paracolic gutters and subphrenic spaces – Lesser sac usually does not fill with ascites, with the exception of cases with tense ascites or ascites due to a local source (gastric ulcer or pancreatitis) □ Otherwise, lesser sac fluid suspicious for ascites related to carcinomatosis or infection • Morphology ○ Free-flowing ascites: Conforms to shape of surrounding structures and does not deform normal shape of adjacent organs or exert mass effect – Fluid insinuates itself between organs ○ Loculated fluid: Fluid demonstrates rounded contour and appears encapsulated – Loculated ascites fluid exerts mass effect and displaces adjacent structures (such as bowel loops) • Key concepts and descriptors ○ Ascites typically divided into 2 types – Transudative ascites is caused by high portal venous pressures and is characterized by low protein, low LDH, normal glucose, and low specific gravity □ Transudative ascites is simple ascites fluid that is most often caused by cirrhosis, hepatitis, heart failure, renal failure, or hypoproteinemia – Exudative ascites characterized by high protein and high specific gravity □ Exudative ascites related to multiple causes, such as infection, ischemia, peritoneal carcinomatosis, peritonitis, and pancreatitis

Radiographic Findings • Abdominal radiograph: Insensitive for fluid, as diagnosis of ascites on radiographs requires a substantial amount of fluid to be present (usually > 500 cc) ○ Diffuse haziness and increased density of abdomen ○ Poor visualization of normally visualized soft tissue structures, such as psoas and renal outline – Obliteration of hepatic and splenic angles ○ Bulging of flanks due to fluid distending abdomen ○ Separation of small bowel loops with centralization of floating gas-containing small bowel ○ Hellmer sign: Lateral edge of liver medially displaced from adjacent thoracoabdominal wall ○ Symmetric densities on sides of bladder (dog ears sign) ○ Medial displacement of ascending and descending colon ○ Lateral displacement of properitoneal fat line

CT Findings • Transudative ascites ○ Typical transudative ascites has density of 0-15 Hounsfield units (HU) and appears free flowing ○ Small amounts of ascites typically seen in right perihepatic space, Morison pouch, and pouch of Douglas ○ Larger amounts of fluid accumulate in paracolic gutters – Ascites can cause centralization of bowel loops – Ascites accumulating in central abdomen may have triangular configuration within leaves of mesentery ○ Look for associated evidence of liver, heart, or kidney failure (most common causes of transudative ascites) • Exudative ascites ○ Exudative ascites typically demonstrates increasing density of fluid with increasing protein content – Exudative ascites often mildly hyperdense relative to transudative ascites (15-30 HU) – May demonstrate complexity, including septations, peritoneal thickening/enhancement, and loculation ○ Ascites related to peritoneal carcinomatosis: Complex ascites with nodularity and thickening of adjacent peritoneum and frequent loculation of ascites ○ Chylous ascites: Intraperitoneal and extraperitoneal fluid usually of water density, but can be < 0 HU or demonstrate fat-fluid levels (due to fat content) ○ Bile ascites: Low density fluid (usually < 15 HU) most typically localized adjacent to liver or biliary structures ○ Urinary ascites: Low density fluid (< 15 HU) usually localized adjacent to urinary tract (and site of leak) – IV contrast accumulates within ascites fluid during excretory phase (after renal concentration and excretion) ○ Cerebrospinal fluid ascites: Small amount of free fluid is expected with ventriculoperitoneal shunt – Localized collection near tip of shunt catheter is abnormal and implies malfunction ○ Pancreatic ascites: Most often accumulates surrounding pancreas, lesser sac, and anterior pararenal space – Usually seen in presence of severe pancreatitis or disruption of pancreatic duct

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

MR Findings • Transudative ascites: Fluid signal on T1WI (hypointense) and T2WI (hyperintense) • Exudative: Usually simple fluid signal on T1WI and T2WI, but internal complexity and protein can result in intermediate T1 and T2 signal ○ Internal complexity (such as debris or septations) usually more apparent on MR compared to CT • Artifacts ○ Flow voids related to bulk motion of fluid usually more evident on SSFSE/HASTE sequences (compared to T2 FSE or steady state free precession/SSFP) and should not be misinterpreted as tumor or carcinomatosis ○ Failure of fat suppression adjacent to sites of susceptibility (i.e., gas within bowel) can be misinterpreted as ascites fluid – Ascites often erroneously diagnosed near diaphragm due to susceptibility from adjacent lung

Ultrasonographic Findings • Uncomplicated ascites 85

Peritoneum, Mesentery, and Abdominal Wall

Ascites ○ Homogeneous, freely mobile, anechoic fluid with posterior acoustic through transmission ○ Free fluid forms acute angles where fluid borders organs, should shift with changes in patient position, and should compress with increased transducer pressure ○ Polycyclic, lollipop, arcuate appearance: Small bowel loops arrayed on either side of vertically floating mesentery in patients with massive ascites ○ Transverse and sigmoid colon usually float on top of fluid (nondependent gas content when patient is supine) • Complicated exudative ascites ○ May demonstrate internal echoes or septations ○ Fluid is often loculated (i.e., not freely mobile with changes in position or transducer compression) – Loculated ascites implies adhesions, malignancy, or infection of peritoneum

Imaging Recommendations • US: Simple, cost-effective, and very sensitive (can detect volumes of ascites as small as 5-10 mL) • CT: Valuable for evaluating underlying cause of ascites

DIFFERENTIAL DIAGNOSIS Hemoperitoneum • High-attenuation fluid which is typically > 30 HU (30-60 HU), although will gradually decrease in density over time ○ Sentinel clot: Highest density (> 60 HU) blood products accumulate near site of bleeding

Malignant Ascites • Exudative ascites which is often loculated and associated with nodular thickening of peritoneum and carcinomatosis • Known underlying malignancy and imaging evidence of metastatic disease are keys to correct diagnosis

Infectious Ascites • Exudative ascites with fluid demonstrating slightly higher attenuation (15-30 HU) than simple fluid • Presence of peritoneal thickening/enhancement, septations, and frank loculated fluid collections (with peripheral rim enhancement) are clues to correct diagnosis

Physiologic Free Fluid • Small fluid in cul-de-sac is physiologic in premenopausal females and should not be interpreted as pathologic ascites • Free fluid always considered abnormal in a male patient

PATHOLOGY General Features • Etiology ○ Hepatic: Cirrhosis, portal hypertension, Budd-Chiari, portal vein thrombosis, hepatitis ○ Cardiac: Congestive heart failure, constrictive pericarditis, cardiac tamponade ○ Renal: Nephrotic syndrome, chronic renal failure ○ Neoplasm: Carcinomatosis due to ovary, colon, gastric, and pancreatic malignancies (amongst many others) ○ Infections: Bacterial, fungal, parasitic, or TB ○ Trauma: Blunt, penetrating, or iatrogenic injury – Bile ascites: Trauma, cholecystectomy, biliary or hepatic surgery, biopsy, percutaneous drainage 86

– Urinary ascites: Trauma to bladder or collecting system vs. iatrogenic injury from instrumentation – Chylous: Trauma to cisterna chyli or other lymphatics ○ Hypoalbuminemia, protein-losing enteropathy

Gross Pathologic & Surgical Features • • • •

Transudate: Clear, colorless, or straw colored Exudate: Yellowish or hemorrhagic Neoplasm: Bloody, clear, or chylous Pyogenic: Turbid, chylous, yellowish white, or milky

Microscopic Features • Ascites fluid may contain blood cells, colloids, protein molecules, or crystalloids (e.g., glucose and water) • Serum-ascites albumin gradient (SAAG): Difference of < 11 g/L suggests exudative ascites • Polymorphonuclear leukocyte count > 500/mm³ suggests infection or pancreatic ascites

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Small ascites may be asymptomatic, but larger volumes result in abdominal discomfort and distension ○ Physical examination: Bulging flanks, flank dullness, fluid wave, umbilical hernia, or penile/scrotal edema • Paracentesis with US guidance or blind tap (to discern nature of ascites) required in all patients with new onset ascites of unknown etiology or chronic ascites with fever, abdominal pain, renal insufficiency, or encephalopathy ○ Fluid analysis: Protein, lactate dehydrogenase, amylase, blood cell count with differential, bacteriology, cytology, pH, triglycerides

Natural History & Prognosis • Complications: Spontaneous bacterial peritonitis, respiratory compromise, anorexia

Treatment • Sodium restriction and diuretics for transudative ascites • Cases with refractory transudative ascites may require large volume paracentesis ○ Some patients may be candidates for peritoneovenous shunting (LeVeen, Denver catheters) or transjugular intrahepatic portosystemic shunt (TIPS) • Patients with exudative ascites will not respond to salt restriction or diuretics, and only treatment is therapeutic paracentesis or treatment of underlying cause of ascites

DIAGNOSTIC CHECKLIST Consider • Recognize signs of exudative ascites and consider paracentesis for specific diagnosis

SELECTED REFERENCES 1.

Farsad K et al: Clinical and radiologic evaluation of patients before TIPS creation. AJR Am J Roentgenol. 203(4):739-45, 2014

Ascites Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial T2 FS MR demonstrates loculated T2 hyperintense ascites . Notice the presence of discrete nodules within the ascites fluid, reflecting the fact that this is malignant ascites in a patient with peritoneal carcinomatosis from appendiceal cancer. (Right) Axial NECT in a patient after small bowel transplantation demonstrates fat-fluid levels within fluid collections that indicate the chylous nature of the fluid and that it represents leakage from small bowel lymphatics.

(Left) Axial CECT shows complex, loculated ascites from bile peritonitis due to a biliary injury. Lesser sac ascites, which displaces the stomach and duodenum in this case, is usually due to a local source (e.g., pancreatitis, gastric ulcer), peritonitis, or carcinomatosis. (Right) Axial T1 FS C+ MR demonstrates loculated ascites in the pelvis. Notice the extensive peritoneal thickening and hyperenhancement more posteriorly in the pelvis, consistent with this patient's malignant ascites and peritoneal carcinomatosis.

(Left) Axial CECT shows marked thickening of the distal stomach , compatible with malignancy. Extensive ascites is present with nodular thickening of the parietal peritoneum , indicating malignant ascites from gastric carcinoma. (Right) Axial CECT in the same patient shows the tumor extending along the gastrocolic ligament to involve the transverse colon . Note the nodular thickening of the parietal peritoneum . GI malignancies are the most common source of malignant ascites in men.

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Omental Infarct KEY FACTS

TERMINOLOGY • Fat necrosis caused by interruption of arterial blood supply to omentum

IMAGING • CT appearance ○ Heterogeneous, encapsulated mass located within omentum (usually in right lower quadrant) – Surrounding inflammatory change and fat stranding ± small free fluid ○ Variable attenuation, but usually foci of fat attenuation ○ Usually well circumscribed with peripheral hyperdense rim – May appear ill defined as poorly marginated fat stranding without discrete mass in earliest stages ○ No central dot sign (seen with epiploic appendagitis) ○ Whorled pattern of vessels leading to infarct may reflect torsion of vessels feeding omentum • Ultrasound appearance

(Left) Axial CECT in a patient with abdominal pain demonstrates an ill-defined, fat-containing mass in the omentum with a subtle peripheral rim, in keeping with an omental infarct. The patient's pain resolved in a few days with conservative therapy. (Right) Axial CECT demonstrates a wellcircumscribed fatty mass with a peripheral hyperdense rim in the right omentum. The patient had experienced RLQ pain about 1 week earlier, and this was thought to be a subacute omental infarct.

(Left) Axial CECT in a patient with abdominal pain shows a classic omental infarct as a fatty mass with a hyperdense rim adjacent to the ascending colon. (Right) Axial CECT in the same patient demonstrates a "swirled" appearance of an omental vessel within the infarcted omentum, indicating twisting of the omental pedicle, which may be the etiology of the infarct in some cases.

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○ Hyperechoic, nonmobile, noncompressible fixed mass arising in omentum – Decreased or absent flow within echogenic mass ○ Focal tenderness with graded compression

PATHOLOGY • Most cases idiopathic (obesity is predisposing factor) • Other causes include abdominal surgery, trauma, incarcerated hernia, etc.

CLINICAL ISSUES • Clinical presentation may mimic acute appendicitis ○ Usually normal WBC and lack of nausea, vomiting, diarrhea, or constitutional symptoms • Benign disorder almost never associated with complications • Usually self-limiting process that resolves spontaneously and should be treated only with pain management • If diagnosed prospectively on CT, surgery should not be performed

Omental Infarct

Definitions • Fat necrosis caused by interruption of arterial blood supply to omentum

IMAGING General Features • Best diagnostic clue ○ Focal mass of heterogeneous density within omental fat with surrounding soft tissue inflammation • Size ○ Varies from 3.5-15 cm ○ Larger infarcts often associated with surgery • Morphology ○ Focal heterogeneous mass composed of inflamed omental fat ± hemorrhage ○ Usually well circumscribed, and appear triangular, ovoid, or cake-like in shape

CT Findings • Heterogeneous, encapsulated mass located within omentum between anterior abdominal wall and colon ○ Can have variable internal attenuation, but usually some internal foci of fat attenuation (-20 to -50 HU) ○ Usually well-circumscribed margins with peripheral hyperdense rim, particularly when occurring after surgery – Infarcts in earliest stages may appear ill defined: Sites of poorly marginated fat stranding without discrete mass ○ Does not have central dot sign seen with epiploic appendagitis ○ Whorled pattern of vessels leading to infarct may reflect torsion of vessels feeding omentum • Often associated with surrounding inflammatory change and fat stranding ± small free fluid • May be adherent to either colon or parietal peritoneum ○ Only rarely causes reactive colonic wall thickening ○ Rarely causes reactive thickening of overlying abdominal wall • Usually located in right inferior omentum, especially when idiopathic ○ Usually located adjacent to site of surgery when occurring in postoperative setting

Ultrasonographic Findings • Grayscale ultrasound ○ Echogenic, nonmobile, noncompressible fixed mass arising in omentum – Associated with focal tenderness when graded compression applied to site – Echogenic fat surrounding mass (reflects inflammation) ± small free fluid • Color Doppler ○ Decreased or absent flow within echogenic mass

Nuclear Medicine Findings • PET/CT ○ Omental infarcts may demonstrate FDG avidity suggesting tumor (if not correlated with CT appearance)

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Acute Appendicitis • Can mimic omental infarction clinically, but distinction readily made with cross-sectional imaging • Dilated appendix with wall thickening, mucosal hyperemia, and periappendiceal fat stranding, inflammation, and free fluid ○ May demonstrate reactive wall thickening of cecum or terminal ileum ○ Fluid collection, abscess, or ectopic gas in setting of perforation ○ Appendicolith may be seen in 10-15% of cases • Noncompressible appendix 7 mm on graded compression US often with increased color flow vascularity

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Epiploic Appendagitis • Benign and self-limited disorder: 1% of patients with acute right lower quadrant pain ○ Most commonly caused by primary thrombosis or torsion of epiploic appendage, but rarely secondary to adjacent inflammation (diverticulitis, appendicitis, etc.) • May appear similar to omental infarct, but distinction is irrelevant, as both entities treated conservatively • CT: Small fatty mass with hyperattenuating ring abutting colon with mild adjacent fat stranding ○ Central dot sign due to thrombosed vessel commonly present, not seen with omental infarcts ○ May rarely cause reactive wall thickening of colon and thickening of parietal peritoneum ○ Most common in left lower quadrant (rectosigmoid), unlike omental infarcts which occur in right lower quadrant

Liposarcoma • Large omental infarcts can mimic fatty tumor (i.e., liposarcoma) • Distinction based on clinical presentation (omental infarcts present with acute pain) and change over time (tumor grows over time while infarct should get smaller)

Pancreatitis With Extrapancreatic Fat Necrosis • Focal or diffuse enlargement of pancreas with peripancreatic fluid and stranding ± fluid collections • Release of pancreatic enzymes into surrounding tissues can cause extrapancreatic fat necrosis ○ May appear focal and mimic omental infarct or tumor

Fibrosing/Sclerosing Mesenteritis • Spiculated soft tissue mass usually found in root of small bowel mesentery ○ May be associated with calcification, mimicking mesenteric carcinoid metastasis • Often results in thickening, infiltration, displacement, and narrowing of adjacent bowel loops • Usually located in left upper quadrant mesentery (not omentum)

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Omental Infarct

• Peritoneal tumor implants usually appear more nodular or solid in appearance ○ Early carcinomatosis may appear as ill-defined nodularity and stranding in omentum, potentially mimicking infarct • Usually multifocal, whereas infarct is solitary • Known history of primary malignancy (ovarian, gastrointestinal, etc.)

PATHOLOGY General Features • Etiology ○ Rare entity due to abundant collateral vessels supplying omentum – Omental infarcts tend to occur in right inferior omentum due to its more tenuous blood supply – Right epiploic vessels involved in 90% of cases – Hemorrhagic infarction with fat necrosis inflammatory infiltrate fibrosis and retraction healing or autoamputation ○ Most cases are idiopathic – Obesity is known predisposing factor ○ Multiple other secondary causes reported – Abdominal surgery accounts for vast majority of cases with known cause – Blunt trauma – Incarcerated hernia – Omental torsion ("twisting" of omentum with compromise of omental blood supply) □ Sometimes idiopathic with predisposition for children □ More commonly secondary to omental cysts, tumors, post-surgical scarring, or hernias – Vigorous activity (reported in marathon runners) □ May result in "low flow" to omental blood vessels – Vascular congestion, kinking of vessels (usually caused by sudden positional changes), and sudden increases in intraabdominal pressure – Heart failure and digitalis – Rarely superior mesenteric artery occlusion

Microscopic Features • Fat necrosis with inflammatory infiltrate ○ Predominantly plasmocytic, lymphocytic, and histiocytic cells • Collagenous scarring in chronic cases

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Subacute right lower quadrant abdominal pain – Right-sided in 90% of cases ○ Mimics acute appendicitis or rarely acute cholecystitis ○ Fever, nausea, vomiting, diarrhea, and other constitutional symptoms are uncommon (unlike appendicitis) but do rarely occur – Children are more likely to exhibit constitutional symptoms than adults • Other signs/symptoms 90

○ Lab data – WBC and ESR are normal or mildly elevated ○ Physical examination – Rebound tenderness in right lower quadrant ± palpable mass

Peritoneal Carcinomatosis

Demographics • Age ○ Elderly obese people (85% of cases) ○ Less common in children (15% of cases) • Gender ○ M:F = 2:1 • Epidemiology ○ Very rare (1/250 as common as appendicitis) ○ Adults (85%) ○ Children (15%) – Primary infarction more prevalent in young patients

Natural History & Prognosis • Benign, self-limited disorder • Complications (very rare) ○ Abscess ○ Adhesions with eventual development of bowel obstruction • Prognosis ○ Usually self-limiting process that resolves spontaneously in 1-4 months • Surgery can be avoided if omental infarct prospectively differentiated from other entities (such as appendicitis) on imaging

Treatment • Conservative management ○ Pain management with NSAIDs ○ If diagnosed prospectively on CT, surgery should not be performed • Laparoscopic excision sometimes considered if patient mistakenly underwent laparoscopy for suspected appendicitis ○ May be missed at laparoscopy unless there is careful evaluation of omentum ○ Theoretically might reduce risk of developing adhesions and prevent future bowel obstruction

DIAGNOSTIC CHECKLIST Consider • Look carefully for omental infarction in patients with suspected appendicitis with normal appendix on CT

Image Interpretation Pearls • Heterogeneous, encapsulated, fat-containing mass in right lower quadrant omentum with surrounding fat stranding, inflammation, and small free fluid

SELECTED REFERENCES 1.

Patlas MN et al: Cross-sectional imaging of nontraumatic peritoneal and mesenteric emergencies. Can Assoc Radiol J. 64(2):148-53, 2013

Omental Infarct Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT demonstrates a small, fatcontaining mass with a hyperdense rim and adjacent inflammation in the right lower quadrant (RLQ) omentum, a classic appearance and location for an omental infarct. (Right) Coronal CECT in a patient after laparoscopic distal pancreatectomy demonstrates a large fat-containing mass in the left upper quadrant omentum, representing a large omental infarct. Omental infarcts after surgery can be quite large and in proximity to the surgical bed.

(Left) Coronal CECT in a patient with pain shows an encapsulated fatty mass in the RLQ omentum with surrounding fat stranding, characteristic of an omental infarct. (Right) Axial CECT in a patient who had recently undergone distal pancreatectomy shows a large circumscribed mass in the LUQ omentum. Note the presence of internal fat density within the mass. Omental infarcts, as in this case, can be quite large and mimic a tumor (such as a liposarcoma) or carcinomatosis.

(Left) Axial CECT in a patient with polyarteritis nodosa and abdominal pain shows focal fat stranding in the anterior omentum, corresponding to the site of the patient's pain. This represents an omental infarct likely related to the vasculitis. (Right) Axial CECT in an 11year-old boy with RLQ pain shows a well-circumscribed, oval, fat-density mass in the RLQ with adjacent fat stranding. The referring physician favored a diagnosis of appendicitis and opted for surgery, where an omental infarct was confirmed.

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Inguinal Hernia KEY FACTS

IMAGING • Direct inguinal hernia: Hernia passes through Hesselbach triangle (bounded by inguinal ligament, lateral margin of rectus abdominis, and inferior epigastric artery) ○ CT: Arises anteromedial to origin of inferior epigastric artery and extends through anterior abdominal wall lateral to rectus muscle – Contents of inguinal canal (testicular vessels, vas deferens) can be seen as a crescent of density along lateral aspect of hernia as it protrudes – No compression of femoral artery/vein • Indirect inguinal hernia: Hernia passes through internal inguinal ring, down inguinal canal, and emerges at external ring ○ CT: Arises superolateral to inferior epigastric vessels and extends lateral to medial within inguinal canal ○ Lateral crescent sign not present with indirect hernias • Ultrasound: Can scan patient either with Valsalva maneuver or in upright position to precipitate hernia

(Left) Illustration demonstrates a direct inguinal hernia , with the hernia neck located medial to the inferior epigastric artery and vein . (Right) Illustration demonstrates an indirect inguinal hernia , with the hernia neck located lateral to the inferior epigastric artery and vein . The inferior epigastric vessels serve as the key landmark in distinguishing direct and indirect inguinal hernias.

(Left) Axial CECT in an elderly man who presented with groin pain and a palpable mass demonstrates a right inguinal hernia. Note that the hernia sac is in the right inguinal canal and medial to the inferior epigastric vessels , identifying it as a direct inguinal hernia. (Right) Axial CECT in an elderly man who presented with a large groin mass and a small bowel obstruction demonstrates a large right inguinal hernia containing sections of the small bowel , colon , and omentum .

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○ US can determine reducibility of hernia (unlike CT) and identify reducible hernias that may not be seen on CT

PATHOLOGY • 75-80% of all hernias occur in inguinal region, with indirect hernias 5x more common than direct • Indirect inguinal hernia usually a congenital defect due to patency of processus vaginalis, while direct hernias are acquired due to abdominal wall weakness

CLINICAL ISSUES • Much more common in men than women • Symptoms often worse when standing, lifting, or straining • Complications: Incarceration and strangulation (much more common with indirect than direct inguinal hernia) • Emergent surgical repair (laparoscopic or open) in patients with a strangulated inguinal hernia • Symptomatic hernias usually surgically repaired on elective basis, although conservative management possible in some asymptomatic or minimally symptomatic patients

Inguinal Hernia

Abbreviations • Inguinal hernia (IH)

Synonyms • Pelvic hernia, groin hernia

Definitions • Inguinal hernia: External hernia with orifice in inguinal location • External hernia: Abnormal protrusion of intraabdominal tissue through defect in abdominal/pelvic wall, with extension outside abdominal cavity

IMAGING General Features • Location ○ Indirect IH: Hernia passes through internal inguinal ring, down inguinal canal, and emerges at external ring – Lateral IH: Arise superior and lateral to epigastric vessels (lateral umbilical fold) – Can extend along spermatic cord into scrotum (i.e., complete hernia) in males – Can follow course of round ligament of uterus into labium majus in females – Juxtafunicular hernia: Indirect hernia that passes outside spermatic cord into surrounding soft tissues – Occur most often on right in both men and women ○ Direct IH: Hernia passes through Hesselbach triangle (in floor of inguinal canal bounded by inguinal ligament, lateral margin of rectus abdominis, and inferior epigastric artery) – Arise medial to course of inferior epigastric vessels (IEV) – Not contained in spermatic cord and generally does not pass into scrotum – Medial umbilical fold divides Hesselbach triangle into medial and lateral parts, and direct IH can be divided into medial and lateral types • Morphology ○ Indirect IH within spermatic cord has smooth contour with an elongated oblique course – Juxtafunicular hernia has more irregular contour without protrusion into preformed sac ○ Direct IH appears broad and dome-shaped

CT Findings • Some IH, particularly when small, have tendency to reduce when patient is supine and may be missed on CT • Primary landmark is inferior epigastric artery, which arises opposite to origin of deep circumflex iliac artery from external iliac artery • Direct hernia: Arises anteromedial to origin of inferior epigastric artery, extends through anterior abdominal wall lateral to rectus muscle, and courses below inferior epigastric artery ○ Contents of inguinal canal (testicular vessels, vas deferens) can be seen as a crescent of density along lateral aspect of hernia as it protrudes ○ No compression of nearby femoral artery and vein (unlike femoral hernias)

○ Relationship of hernia sac relative to pubic tubercle may help differentiate inguinal and femoral hernias – IH seen anterior to horizontal plane connecting pubic tubercles (femoral hernias posterior) • Indirect hernia: Arises superolateral to inferior epigastric vessels and extends lateral to medial within inguinal canal ○ Lateral crescent sign seen with direct hernias not present with indirect hernias, as normal contents of inguinal canal are not compressed • Direct and indirect hernias can very rarely be visualized in same groin: "Saddlebag" or "pantaloon" hernia (combinedtype hernia) • CT very helpful for identifying contents of hernia sac (omental fat, bowel, bladder) and identifying complications (bowel obstruction, ischemia, perforation, etc.) ○ IH described as "sliding" hernias when partially retroperitoneal structures (bladder, distal ureters, ascending/descending colon) are within hernia sac – Key to identify, as blood vessels supplying herniated segments may be injured during surgical repair or trauma ○ Appendix within hernia sac: Amyand hernia ○ Meckel diverticulum within hernia sac: Littre hernia ○ Also helpful if other disease process mimicking or precipitating hernia suspected ○ CT should be first-line modality in patients presenting with acute symptoms from hernia

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Ultrasonographic Findings • Some debate in literature regarding efficacy of US in diagnosing hernias: Various studies have shown sensitivities ranging from 29-100% ○ Most useful if patient presents nonurgently with history suggesting reducible IH • Typically high-frequency transducer (> 10 MHz) best, since IH are superficial, but lower frequencies may be utilized in more obese patients ○ Ultrasound probe placed longitudinal to inguinal canal and anterior to inferior epigastric artery (at site of origin from external iliac artery) • Patient initially scanned supine, but advantage of US is ability to scan patient either with Valsalva maneuver or in upright position to precipitate hernia (if hernia not seen at rest in supine position) ○ Bowel loops may peristalse within hernia sac and may aid in identification of hernia ○ US can determine reducibility of hernia (unlike CT) and identify reducible hernias that may not be seen on CT due to supine scan position • Primary sonographic landmarks are pubic tubercle and inferior epigastric artery (identified along lateral border of rectus abdominis and can be traced back to external iliac artery) • Indirect IH: Hernia seen to originate lateral to inferior epigastric artery and extend medially towards pubic tubercle ○ Valsalva maneuver: Impaired swelling of pampiniform plexus • Direct IH: Hernia seen to originate medial to inferior epigastric artery and extend anteriorly toward probe ○ Valsalva maneuver: In direct IH, distended pampiniform plexus is displaced by hernia sac 93

Peritoneum, Mesentery, and Abdominal Wall

Inguinal Hernia

• Radiography ○ Soft tissue density or gas-containing mass overlying obturator foramen on affected side suggests presence of hernia ○ Presence of dilated bowel loops with convergence of distended intestinal loops toward inguinal region suggests bowel obstruction due to inguinal hernia ○ Barium examination of small or large bowel: Tapered narrowing or obstruction of intestinal segments entering hernia orifice

Imaging Recommendations • Best imaging tool ○ CECT in patients with acute symptoms or suspicion of complications related to hernia ○ US is appropriate first-line modality in patients with nonurgent presentation

DIFFERENTIAL DIAGNOSIS Femoral Hernia • Protrusion of abdominal contents through femoral ring and into femoral canal • Omental fat or bowel herniating into femoral canal medial to femoral vein and inferior to inferior epigastric vessels • Femoral vein often indented/compressed by hernia sac • Hernia sac located posterior to horizontal plane of pubic tubercle, while IH located anterior • More common in women

Lymphadenopathy • Soft tissue nodule near inguinal ligament might mimic IH clinically, but distinction easily made with imaging

Spermatic Cord Lipoma or Liposarcoma • Rare fat-containing masses that typically grow into scrotum, but can involve inguinal canal and mimic an IH containing omental fat • Well-differentiated liposarcomas or lipomas may be difficult to differentiate from omental fat in hernia, but lesions usually appear more mass-like and liposarcomas often demonstrate some internal complexity

PATHOLOGY General Features • Etiology ○ 75-80% of all hernias occur in inguinal region, with indirect hernias 5x more common than direct ○ Indirect IH considered most often congenital defect due to patency of processus vaginalis and weakness of crus lateralis at lateral aspect of inguinal canal – Although congenital, may not become clinically apparent until later in life ○ Direct IH considered acquired lesion arising due to weakness in transversalis fascia of posterior wall of inguinal canal in Hesselbach triangle

CLINICAL ISSUES Presentation • Most common signs/symptoms 94

○ Wide spectrum of presentations depending on hernia size – May be asymptomatic in many (especially when small), present as palpable lump in groin, heavy sensation in groin, or cause groin pain □ Symptoms often when standing, lifting, or straining – Incarcerated or strangulated hernias may have severe fulminant presentations ○ Most hernias diagnosed on clinical examination (without imaging), with hernia best palpated with patient standing, coughing, or performing Valsalva maneuver

Radiographic Findings

Demographics • Age ○ Indirect IH may occur from infancy to old age, but generally present by 5th decade – Occurs in 1-3% of all children with 1.5-2x greater incidence in premature infants – Pediatric IH almost always indirect with increased incarceration risk □ Usually right (60-75%) but often bilateral (10-15%) ○ Direct IH increases in incidence with age • Gender ○ Indirect IH 5-10x more common in men ○ Direct IH occurs mostly in men

Natural History & Prognosis • Complications: Incarceration, strangulation, and bowel obstruction ○ Direct IH rarely incarcerated and has a lower association with strangulation ○ Indirect IH accounts for 15% of intestinal obstructions ○ Diverticulitis, appendicitis, or primary/metastatic tumor may occur within hernia sac • IH may recur after herniorrhaphy in ~ 20% ○ Direct IH may develop after indirect IH repair

Treatment • Emergent surgical repair (laparoscopic or open) in patients with a strangulated IH • Symptomatic hernias surgically repaired on elective basis • Conservative management possible in patients who are asymptomatic or have minimal symptoms

SELECTED REFERENCES 1. 2. 3.

Burkhardt JH et al: Diagnosis of inguinal region hernias with axial CT: the lateral crescent sign and other key findings. Radiographics. 31(2):E1-12, 2011 Lassandro F et al: Abdominal hernias: Radiological features. World J Gastrointest Endosc. 3(6):110-7, 2011 Light D et al: The role of ultrasound scan in the diagnosis of occult inguinal hernias. Int J Surg. 9(2):169-72, 2011

Inguinal Hernia Peritoneum, Mesentery, and Abdominal Wall

(Left) Coronal CECT demonstrates multiple dilated loops of small bowel in the pelvis, compatible with small bowel obstruction. (Right) Coronal CECT in the same patient demonstrates that the small bowel extends into a right inguinal hernia with a transition point in the hernia sac. This incarcerated hernia could not be manually reduced, and urgent surgery was performed for repair.

(Left) Grayscale ultrasound of an inguinal hernia shows small bowel loops in the right scrotal sac . Note the contralateral left scrotum and testis . (Right) Coronal T2 MR demonstrates a "sliding" inguinal hernia containing a portion of the bladder . Sliding inguinal hernias contain portions of partially retroperitoneal structures, such as the bladder, and care must be taken at surgery to avoid damage to these structures or their supplying vessels.

(Left) Barium small bowel follow-through study in a patient with a right inguinal hernia shows the herniated small bowel lying over the right femoral head. Note the constriction of the bowel as it passes through the inguinal ring. (Right) Grayscale ultrasound shows echogenic omentum herniating into the inguinal canal. Note the fluid within hernia sac and inferiorly displaced ipsilateral testis . Omental fat on US is echogenic or slightly hypoechoic tissue without peristalsis.

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Femoral Hernia KEY FACTS

TERMINOLOGY • Protrusion of abdominal contents through femoral ring into femoral canal

IMAGING • Omental fat or bowel herniating into femoral canal medial to femoral vein and inferior to inferior epigastric vessels • Femoral vein often indented or compressed by hernia sac • Hernia sac located posterior and lateral to pubic tubercle • Narrow, funnel-shaped neck • Twice as common on right side compared to left

TOP DIFFERENTIAL DIAGNOSES • Inguinal hernia ○ Inguinal hernias seen anterior to horizontal plane of pubic tubercle ○ Abdominal contents within inguinal canal anteromedial to femoral vessels with extension into scrotum • Obturator hernia

(Left) Illustration of a femoral hernia demonstrates a characteristic "knuckle" of small bowel closely associated with the femoral vein . Femoral hernias are usually found medial to the femoral vessels with frequent compression of the femoral vein. (Right) Axial CECT demonstrates a herniated small bowel loop lying within the femoral canal, compressing the femoral vessels, compatible with a femoral hernia.

(Left) Axial CECT shows a loop of thickened, hyperemic bowel herniating into the right groin medial to the femoral vessels. Notice that the femoral vein is being compressed, and the herniated bowel lies posterolateral to the pubic tubercle. (Right) Coronal CECT in the same patient shows multiple dilated small-bowel loops with a transition point within the hernia. This thickened, hyperenhancing bowel within the hernia sac was found to be ischemic at surgery. Femoral hernias are at high risk for strangulation and obstruction.

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○ Hernia into superolateral aspect of obturator canal • Lymphadenopathy

CLINICAL ISSUES • Primarily occur in elderly women, with 36% occurring in patients > 80 years old • Relatively uncommon, representing only 2-4% of groin hernias in adults ○ ~ 1/10 as common as inguinal hernias ○ ~ 1/3 of groin hernias occur in women • Highest risk of incarceration/strangulation (25-40%) among all groin hernias ○ 8-12x more prone to incarceration/strangulation than inguinal hernias • Significant risk of mortality, primarily related to incarceration and intestinal obstruction ○ Mortality: 1% in 70-79 age group; 5% in 80-90 age group • Symptomatic hernia (or newly discovered asymptomatic hernia) should undergo immediate surgical repair

Femoral Hernia

PATHOLOGY

Synonyms

General Features

• Crural hernia, enteromerocele, femorocele

• Etiology ○ May be partially attributable to congenital defect in insertion of transversalis fascia to ileopubic tract ○ Femoral ring connective tissues may dilate during pregnancy, placing women at risk for femoral hernia ○ Associated with increased intraabdominal pressure

Definitions • Protrusion of abdominal contents through femoral ring into femoral canal

IMAGING General Features

CLINICAL ISSUES

• Location ○ Protrusion of hernia sac contents at right angle to inguinal canal through femoral ring into femoral canal – Posterior to inguinal ligament, anterior to pubic ramus periosteum (Cooper ligament), and medial to femoral vessels ○ Inguinal ligament not visible on CT as discrete structure, but horizontal plane connecting pubic tubercles defines plane of inguinal ligament – Femoral hernia posterior to plane of pubic tubercle ○ Twice as common on right side compared to left

Presentation

CT Findings

• Age ○ 36% occur in patients > 80 years old ○ < 1% of all groin hernias in children • Gender ○ Predominantly women (M:F = 1:4) • Epidemiology ○ ~ 2-4% of groin hernias in adults ○ ~ 1/10 as common as inguinal hernias ○ ~ 1/3 of groin hernias in women

• Omental fat or bowel herniating into femoral canal medial to femoral vein and inferior to inferior epigastric vessels ○ Femoral vein indented/compressed by hernia sac • Hernia sac located posterior and lateral to pubic tubercle • Narrow, funnel-shaped, or pear-shaped neck

Ultrasonographic Findings • Hernia sac visualized extending medial to femoral vein • Hernia sac may be easier to define with Valsalva maneuver

Radiographic Findings • Herniography: Hernia curves smoothly over superior pubic ramus on all projections ○ Pear-shaped hernia sac with a narrow neck

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Inguinal Hernia • Abdominal contents within inguinal canal anteromedial to femoral vessels with extension into scrotum • Seen anterior to horizontal plane of pubic tubercle • Does not involve femoral canal or compress femoral vessels

Obturator Hernia • Hernia into superolateral obturator canal • Typically occurs in elderly women (80-90%) with a high risk of incarceration

Lymphadenopathy • When medial to femoral vessels, can theoretically mimic femoral hernia on clinical exam, but distinction easily made with CT

• Most common signs/symptoms ○ Swelling, groin discomfort, vague pelvic discomfort ○ Lump usually felt at top of thigh, below groin crease ○ Pain is uncommon in absence of strangulation • Other signs/symptoms ○ Nausea, vomiting, severe pain with strangulated hernia ○ Difficult to diagnose clinically, especially in obese patients, due to deep location of femoral canal

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Demographics

Natural History & Prognosis • Complications ○ High risk of incarceration &/or strangulation (25-40%), primarily due to narrow neck and unyielding margins of femoral ring – Highest rate of incarceration of all groin hernias – 8-12x more prone to incarceration/strangulation than inguinal hernias • Morbidity and mortality ○ Primarily related to incarceration/bowel obstruction ○ Mortality: 1% in 70-79 age group; 5% in 80-90 age group

Treatment • Symptomatic hernia (or newly discovered asymptomatic hernia) should undergo immediate surgical repair • Longstanding, asymptomatic hernias may theoretically be treated conservatively with watchful waiting • No consensus on laparoscopic vs. open surgery

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Femoral hernias lie medial to femoral vein and inferior to inferior epigastric vessels, often compressing femoral vein

SELECTED REFERENCES 1.

Dahlstrand U et al: Limited potential for prevention of emergency surgery for femoral hernia. World J Surg. ePub, 2014

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Obturator Hernia KEY FACTS

IMAGING

PATHOLOGY

• Loop of bowel protruding through obturator foramen ○ Hernia most commonly contains loop of Ileum, although can rarely involve other pelvic viscera (i.e., bladder) ○ Most often trapped between obturator externus and pectineus muscles ○ May also be located between superior and middle fasciculi of obturator externus or between internal and external obturator muscles • Hernia sac exits pelvis near obturator vessels and nerve • Right side more common

• Defect in pelvic floor or laxity of pelvic muscles and fascia • Made worse by any chronic increase in abdominal pressure (COPD, constipation, pregnancy, etc.) • More common in thin or emaciated patients, as preperitoneal fat usually supports obturator canal

TOP DIFFERENTIAL DIAGNOSES • • • •

Inguinal hernia Sciatic hernia Perineal hernia Femoral hernia

(Left) Graphic shows a bowel obstruction caused by an obturator hernia. Strangulated bowel lies deep to the pectineus muscle and superficial to the obturator externus muscle . (Right) Axial CECT in a 73year-old woman shows a protrusion of portions of the bladder into bilateral obturator hernias . Obturator hernias most commonly contain herniated ileum, but other pelvic viscera can also herniate, as in this case.

(Left) Axial CECT in a 90-yearold woman with bowel obstruction shows dilated proximal small bowel loops and collapsed distal bowel . (Right) Axial CECT in the same patient shows the herniated and strangulated segment of the ileum trapped between the obturator externus and the pectineus muscles. These are the classic imaging findings of an obturator hernia.

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CLINICAL ISSUES • Accounts for < 1% of all hernias • > 90% occur in elderly women (mean age 82) • Acute or recurrent small bowel obstruction, partial > complete ○ 80% of patients present with symptoms of bowel obstruction ○ Majority require resection of strangulated small bowel • Rare occurrence and nonspecific signs often lead to late diagnosis ○ Correct clinical diagnosis in only 10–30% of cases ○ Diagnosis best made by CT/MR rather than clinical exam

Obturator Hernia

Definitions • Pelvic hernia protruding through obturator foramen

IMAGING General Features • Best diagnostic clue ○ CT evidence of herniated bowel lying between pectineus and obturator muscles in an elderly woman

Radiographic Findings • Abdominal radiographs or barium studies ○ Small bowel obstruction with a fixed loop containing gas or contrast medium in obturator region

CT Findings • Loop of bowel protruding through obturator foramen ○ Hernia most commonly contains loop of Ileum, although can rarely involve other pelvic viscera (i.e., bladder) ○ Most often trapped between obturator externus and pectineus muscles • 3 forms of hernia (in decreasing frequency) ○ Extending between pectineus and obturator muscles ○ Between superior and middle fasciculi of obturator externus ○ Between internal and external obturator muscles • Hernia sac exits pelvis near obturator vessels and nerve • Right side is more common

Imaging Recommendations • Best imaging tool ○ CECT: Images should include inferior pelvis and upper thigh to ensure hernia is fully imaged

DIFFERENTIAL DIAGNOSIS Inguinal Hernia • Abdominal contents within inguinal canal with extension into scrotum

Sciatic Hernia • Hernia extends through greater sciatic foramen with extension laterally into subgluteal region

Perineal Hernia • Anterior: Through urogenital diaphragm • Posterior: Between levator ani and coccygeus muscle

Femoral Hernia • Hernia extends through femoral ring into femoral canal medial to femoral vein

PATHOLOGY General Features • Etiology ○ Defect in pelvic floor or laxity of pelvic muscles and fascia ○ Made worse by any chronic increase in abdominal pressure (COPD, constipation, pregnancy, etc.) ○ More common in thin or emaciated patients, as preperitoneal fat usually supports obturator canal • Associated abnormalities

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute or recurrent small bowel obstruction, partial > complete – 80% of patients present with symptoms of bowel obstruction – Obstruction is more likely to be intermittent if Richter herniation of bowel into obturator canal ○ May present as tender mass in obturator region on rectal or vaginal examination • Other signs/symptoms ○ Howship-Romberg sign: Pain in medial aspect of thigh/hip with abduction, extension, or internal rotation of knee; flexion relieves pain (25-50% of cases) – Compression and irritation by hernia of the obturator nerve ○ Hannington-Kiff sign: Absent adductor reflex in thigh (15-50% of patients) ○ Obturator neuralgia: Pain or paresthesias along inner surface of thigh to knee • Rare occurrence and nonspecific signs often lead to late diagnosis, with correct clinical diagnosis in only 10–30% of cases

Peritoneum, Mesentery, and Abdominal Wall

○ May be coexistent with other hernias (e.g., inguinal, femoral)

TERMINOLOGY

Demographics • Gender ○ > 90% of obturator hernias occur in elderly women (mean age 82) – Less common complication of pelvic floor laxity (incontinence, prolapse, etc.) • Epidemiology ○ Accounts for < 1% of all hernias – Bilateral obturator hernias rare: 6% of cases

Natural History & Prognosis • Mortality rates up to 25% ○ Diagnosis is elusive; best made by CT or MR rather than by clinical exam

Treatment • Majority require resection of strangulated small bowel • Abdominal/inguinal approach for reduction and repair • Contralateral side exploration is recommended

DIAGNOSTIC CHECKLIST Consider • Obturator hernia in any elderly, debilitated, chronically ill woman with symptoms of recurrent small bowel obstruction and pain along ipsilateral thigh and knee

SELECTED REFERENCES 1.

Hodgins N et al: Obturator hernia: A case report and review of the literature. Int J Surg Case Rep. 4(10):889-92, 2013

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Ventral Hernia KEY FACTS

TERMINOLOGY • Ventral hernia is generic term encompassing variety of hernias through anterior and lateral abdominal wall

IMAGING • Epigastric and hypogastric hernias occur at midline through linea alba ○ Epigastric hernias arise above umbilicus and below xiphoid process ○ Hypogastric hernias arise below umbilicus • Incisional hernias develop at prior abdominal wall incision • CT: Most accurate test for detection of ventral hernias ○ Defect in musculofascial layers of abdominal wall through which omentum ± bowel protrude anteriorly

PATHOLOGY • Depending on hernia type, ventral hernias may be due to either acquired or congenital factors

(Left) Axial CECT demonstrates a hernia containing small bowel arising in the midline above the umbilicus and below the xiphoid, characteristic of an epigastric hernia. The bowel within the hernia appears normal, without evidence of obstruction or ischemia. (Right) Axial CECT in a younger woman with nausea and vomiting due to a strangulated hernia shows herniation of small bowel through a laparoscopy port with bowel obstruction. Bowel distal to the hernia is collapsed .

(Left) Axial CECT in a middleaged woman with nausea and vomiting shows a ventral hernia with strangulated, obstructed small bowel as well as ascites , suggesting bowel ischemia. (Right) Axial CECT demonstrates a ventral hernia containing a markedly thickened, hypoenhancing loop of small bowel . The hernia was not reducible at clinical examination, and the bowel loop within the hernia sac was found to be ischemic at surgery.

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○ Incisional hernias: Acquired hernias at the site of prior surgery, incision, or abdominal wall injury – May be related to previous abdominal surgery, laparoscopy, peritoneal dialysis, or stab wound ○ Epigastric and hypogastric hernias: Possible congenital predisposition due to weakness of linea alba – Acquired risk factors include obesity, increased intraabdominal pressures, and abdominal wall strains

CLINICAL ISSUES • Incisional hernias usually occur during first 4 months after surgery, but can develop many years later • Ventral hernias do not close spontaneously and almost always enlarge over time • Incarceration and strangulation are common • Some debate about treatment of asymptomatic ventral hernias, but in principle, surgical closure is recommended due to risk of incarceration and strangulation ○ Tension-free mesh repair is now gold standard

Spigelian Hernia

TERMINOLOGY • Hernia through defect in aponeurosis of internal oblique and transverse abdominal muscles

IMAGING • Hernia occurs along lateral border of rectus abdominis muscles, inferior/lateral to umbilicus, at level of arcuate line ○ Lies deep to external oblique aponeurosis and muscle ○ 90% within spigelian belt of Spangen, 6-cm transverse band above line joining anterior superior iliac spines. • Most often contains portions of greater omentum, small bowel, or colon ○ Rarely can involve appendix, bladder, and other abdominal/pelvic structures • Defect size is small (usually < 2 cm in size) resulting in narrow hernia neck and high risk of strangulation

TOP DIFFERENTIAL DIAGNOSES • Ventral hernia

• Umbilical hernia • Hernia through laparoscopy port

PATHOLOGY • Probably multifactorial etiology, including congenital weakness of spigelian fascia ○ Usually congenital defect in children and acquired in adults ○ Prior history of abdominal surgery and obesity are biggest risk factors in adults ○ Other risk factors include multiple pregnancies, rapid weight loss, COPD, and trauma

CLINICAL ISSUES • Rare hernia; accounts for 1-2% of anterior abdominal hernias • Difficult to diagnose clinically due to deep anatomic location, especially in obese patients • Surgical treatment indicated in virtually all patients due to high risk of strangulation and incarceration

Peritoneum, Mesentery, and Abdominal Wall

KEY FACTS

(Left) Radiograph in a 52-yearold man with a palpable tender abdominal mass shows a partial colonic obstruction due to herniation of the descending colon through a spigelian hernia (SH). (Right) Axial CECT in the same patient shows herniation of the colon into an intermuscular space between the internal oblique and transverse abdominal muscles (deep) and the external oblique muscle and fascia (superficially).

(Left) Axial CECT more caudal (same patient) shows the defect in the spigelian aponeurosis (that of the internal oblique and transverse abdominal muscles). Note the hernia sac covered by intact aponeurosis of external oblique muscle , and the hernia caudal to the umbilicus and just lateral to the rectus sheath. (Right) CT shows a small bowel obstruction and an SH . The hernia is evident just lateral to the rectus muscle. A segment of small bowel herniates through the defect, resulting in partial obstruction.

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Lumbar Hernia KEY FACTS

TERMINOLOGY • Lumbar hernia: Protrusion of abdominal contents through defect in lumbar region ○ Can occur in either superior lumbar triangle of GrynfelttLesshaft or inferior lumbar triangle of Petit – Superior lumbar triangle of Grynfeltt-Lesshaft defined by 12th rib superiorly, superior border of internal oblique inferiorly, and erector spinae medially – Inferior lumbar triangle of Petit defined by latissimus dorsi muscle medially, iliac crest inferiorly, and free border of external oblique muscle laterally ○ Overall, hernias are more common in superior triangle

IMAGING • Disruption of thoracolumbar fascia at insertion of aponeurosis of internal oblique and transverse abdominal muscles • Hernia may contain extraperitoneal fat, colon, kidney, or intraperitoneal structures (small bowel, ascites)

(Left) Axial CECT shows herniation of retroperitoneal fat that is covered only by the thinned latissimus dorsi muscle in a patient with right flank discomfort. (Right) Axial CECT in the same patient shows the site of herniation immediately above the iliac crest. The lumbar hernia is a defect in the aponeurosis of the internal oblique and transverse abdominal muscles, which should insert on the thoracoabdominal fascia that envelops the quadratus lumborum and erector spinae muscles.

(Left) Axial CECT in an elderly female patient shows a defect in the left thoracolumbar fascia through which the descending colon herniates dorsally. The thoracolumbar fascia should be a strong sheet of tissue that inserts on the iliac crest. (Right) Axial NECT demonstrates a fascial defect in the right lumbar region with herniation of the liver and colon . Notice that while the liver is diffusely steatotic, the liver within the lumbar hernia is higher in density, probably as a result of differential perfusion due to entrapment in the hernia.

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○ Most commonly involved are colon and small bowel

PATHOLOGY • 80% of lumbar hernias are acquired ○ Can be spontaneous (especially in older patients and patients with excessive weight loss) or secondary to trauma, infection, or previous surgery in flank ○ Most commonly occurs following flank incision for renal surgery or iliac crest bone harvesting • 20% of lumbar hernias are congenital

CLINICAL ISSUES • Very difficult to detect (and often missed) on physical examination and more likely to be diagnosed on CT • Incarceration and strangulation are uncommon because of large size of opening into hernia ○ Incarceration more common with acute traumatic lumbar hernias (8-10%) • Treatment: Early surgical repair because repair becomes technically more difficult as hernia enlarges

Umbilical Hernia

TERMINOLOGY • Protrusion of abdominal contents (omental fat ± bowel) into or through anterior abdominal wall via umbilical ring

IMAGING • Hernia sac located at midline (usually upper 1/2 of umbilicus) with protrusion of omental fat ± bowel loops • Fat stranding/fluid within hernia sac (in absence of abnormal bowel) suggests fat necrosis due to incarceration • Findings of bowel ischemia include evidence of bowel obstruction, bowel wall thickening, fat stranding, etc.

TOP DIFFERENTIAL DIAGNOSES • Omphalocele • Ventral hernia • Spigelian hernia

PATHOLOGY • Congenital: Due to incomplete closure of umbilical ring

○ More likely in children with Down syndrome, trisomy 18, mucopolysaccharidoses, Ehlers-Danlos syndrome, and Beckwith-Wiedemann syndrome • Acquired: Results from weakening of cicatricial tissue that normally closes umbilical ring ○ Usually secondary to intraabdominal pressure (e.g., obesity, multiple pregnancies, tense ascites, etc.)

CLINICAL ISSUES • Congenital type: Diagnosed in infancy ○ Congenital type 8x more common in African Americans ○ 80% close spontaneously within 4-6 years ○ Treatment only if hernia is large, symptomatic, or persistent (> 5 years of age) • Acquired type: Develops in later life (usually middle age) ○ Acquired type more common in women (M:F = 1:3) ○ Small and asymptomatic hernias do not undergo repair ○ Symptoms, large hernia size, and incarceration all necessitate surgical repair

Peritoneum, Mesentery, and Abdominal Wall

KEY FACTS

(Left) Axial CECT shows herniation of omental fat into the umbilicus between the rectus sheaths, a characteristic appearance for a small umbilical hernia. (Right) Axial CECT demonstrates an umbilical hernia with internal fluid and fat stranding in a patient with intense pain at this site. Extensive internal fat necrosis due to strangulation was found within the hernia sac at surgery. Incarcerated umbilical hernias with fat necrosis can be very painful but do not necessitate emergent surgery.

(Left) Axial CECT in a middleaged man with cirrhosis shows ascites, dilated small bowel , and an umbilical hernia containing ascites and small bowel. (Right) Axial CECT in the same patient again demonstrates the umbilical hernia . Note the collapsed loop of small bowel leaving the hernia sac, confirming the hernia as the cause of the small bowel obstruction. Umbilical hernias are common among patients with cirrhosis and ascites due to thin abdominal wall musculature and chronically increased intraabdominal pressure.

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Paraduodenal Hernia KEY FACTS

TERMINOLOGY • Congenital internal hernia resulting from protrusion of bowel loops through abdominal mesenteric defect

IMAGING • Paraduodenal hernias may be located either on left or right ○ Left (75%): Protrusion of small bowel through paraduodenal mesenteric fossa of Landzert ○ Right (25%): Protrusion of small bowel through jejunal mesentericoparietal fossa of Waldeyer • CT features ○ Left paraduodenal hernia – Encapsulated "cluster" or sac-like mass of small bowel loops located between pancreatic body/tail and stomach to left of ligament of Treitz – Crowded, engorged mesenteric vessels supplying bowel loops within hernia sac ○ Right paraduodenal hernia

(Left) Graphic shows a left paraduodenal hernia containing dilated proximal jejunal loops in a peritoneal sac. (Right) Small bowel follow-through demonstrates an ovoid cluster of mildly dilated jejunal segments in the left upper quadrant. The outer confines of the hernia sac are well defined. The herniated bowel exerts mass effect on the greater curvature of the stomach, characteristic of a left paraduodenal hernia.

(Left) Abdominal radiograph shows an unusual cluster of dilated jejunal small bowel loops in the left upper quadrant. (Right) Axial CECT in the same patient shows the same cluster of dilated bowel interposed between the pancreas and stomach. Note the displaced inferior mesenteric vein that runs along the anterior edge of the hernia sac. This constellation of findings is characteristic of a left paraduodenal hernia.

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– Clustered, encapsulated small bowel in right upper abdomen lateral/inferior to descending duodenum – Unusual "looping" course of SMA and SMV to supply bowel in hernia sac • Small bowel follow-through ○ Abnormally crowded, clustered bowel loops to left or right side of colon ○ Fixation, stasis, and delayed flow of contrast seen in bowel within hernia sac

PATHOLOGY • Usually result of congenital mesenteric anomaly

CLINICAL ISSUES • Most often occurs in men during 4th-6th decades of life • Smaller hernias clinically silent and reduce spontaneously • Larger hernias more commonly symptomatic (i.e., vague discomfort, abdominal distension, postprandial pain) ○ Very high (~ 50%) lifetime risk of strangulation or incarceration

Paraduodenal Hernia

Definitions • Congenital internal hernia resulting from protrusion of bowel loops through abdominal mesenteric defect

○ Consider bowel ischemia if bowel within hernia sac appears thickened, inflamed, or abnormally enhancing

Fluoroscopic Findings

• Radiography ○ Supine abdomen: Distended, clustered loops of small bowel (SB) in right or left upper abdomen

• Small bowel follow-through ○ Abnormally crowded, clustered bowel loops in right or left upper abdomen with small bowel often absent from pelvis – Left: Circumscribed ovoid mass of jejunal loops in LUQ lateral to ascending duodenum – Right: Ovoid mass of small bowel loops lateral and inferior to descending duodenum – Configuration of small bowel loops appears as sac-like "mass" with confining border ○ In cases with bowel obstruction (either complete or partial), point of transition between dilated and nondilated bowel may be visualized ○ Fixation, stasis, and delayed flow of contrast seen in bowel within hernia sac – Right-sided paraduodenal hernias are often larger than on the left and herniated loops on right are typically more "fixed" than on left ○ Lateral film: Retroperitoneal displacement of herniated bowel loops

CT Findings

Angiographic Findings

• Left paraduodenal hernia ○ Encapsulated "cluster" or sac-like mass of small bowel loops located between pancreatic body/tail and stomach to the left of ligament of Treitz – Bowel loops herniate into sac created by descending and distal transverse mesocolon – Hepatic flexure of colon usually located anterior to hernia sac ○ Hernia sac may exert mass effect on posterior wall of stomach, duodenojejunal junction inferiorly and medially, and transverse colon inferiorly/anteriorly ○ Crowded, engorged mesenteric vessels supplying bowel loops within hernia sac – Inferior mesenteric vein (IMV) and left colic artery lie in anterior and medial border of hernia sac, with IMV often displaced to left • Right paraduodenal hernia ○ Clustered, encapsulated small bowel loops in right upper abdomen lateral and inferior to descending duodenum – Ascending colon located lateral to hernia sac – Mass effect from hernia sac displaces right ureter laterally ○ Unusual "looping" course of superior mesenteric artery (SMA) and vein (SMV) to supply bowel in hernia sac – SMV rotated anteriorly and to left – Twisted vascular jejunal branches behind SMA extend into hernia sac – Main trunk of SMA and right colic vein located along anterior medial border of hernia sac ○ Commonly associated with intestinal nonrotation • Small bowel obstruction (SBO) ○ Bowel loops within hernia sac may or may not be dilated depending on presence or absence of SBO, with transition point between dilated loops within hernia sac and decompressed distal small bowel

• Superior mesenteric arteriogram: Normal jejunal branches arise from left margin of main trunk, abruptly course right, and pass behind to supply herniated loops

IMAGING General Features • Best diagnostic clue ○ CECT: Cluster of dilated bowel loops in right or left upper abdomen with distorted mesenteric vessels • Location ○ Left (75%): Protrusion of small bowel through paraduodenal (lateral to 4th part) mesenteric fossa of Landzert (located near ligament of Treitz) ○ Right (25%): Protrusion of small bowel through jejunal mesentericoparietal fossa of Waldeyer (located inferior to 3rd portion of duodenum)

Radiographic Findings

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT, small bowel follow-through

DIFFERENTIAL DIAGNOSIS Transmesenteric Internal Hernia • Internal hernia that is most often acquired in setting of prior surgery (most commonly Roux-en-Y gastric bypass and liver transplantation) ○ Rarely results from congenital mesenteric defect (usually in pediatric age group) • Clustered loops of small bowel in periphery of abdomen, with loops of bowel abnormally contacting abdominal wall and located lateral to colon ○ Most commonly occur in right hemiabdomen ○ Unlike paraduodenal hernias, transmesenteric hernias do not appear encapsulated or enveloped in a sac • Large transmesenteric hernias may present with bowel obstruction, strangulation, or ischemia

Closed Loop Obstruction • Obstruction of small bowel at 2 separate points in single location forming "closed loop" • Usually caused by adhesive band but rarely can result from internal or external hernia • Dilated bowel loops appear abnormally tethered or clumped, with radiating configuration of bowel and stretched mesenteric vessels toward a central point ○ Mesentery and vasculature may demonstrate whirl sign, with swirling of mesentery and stretched mesenteric vessels toward a central point • High risk of volvulus, strangulation, and bowel infarction 105

Peritoneum, Mesentery, and Abdominal Wall

Paraduodenal Hernia

Pericecal Internal Hernia • Cluster of bowel loops (usually ileum) abnormally located posterior and lateral to cecum with extension into paracolic gutter • Herniation of bowel through pericecal fossa (defect in cecal mesentery) • Lies more inferiorly compared to right-sided paraduodenal hernia (right lower quadrant rather than right upper quadrant)

PATHOLOGY General Features • Etiology ○ Most commonly results from congenital or developmental mesenteric anomaly – Anomalies in mesenteric fixation of ascending or descending colon abnormal openings internal hernia ○ Can also result from complication of surgery or trauma – Abnormal mesenteric defect created during surgery or trauma abnormal mobility of SB and right colon internal hernia ○ Left paraduodenal hernia: Herniation of small bowel via abnormal mesenteric fossa of Landzert – Discrete peritoneal opening lateral to distal duodenum found in 2% of population – Bowel loop herniates into pocket of distal transverse and descending mesocolon, posterior to SMA ○ Right paraduodenal hernia: Herniation via abnormal mesentericoparietal fossa of Waldeyer – Fossa of Waldeyer seen in ~ 1% of population – Jejunal mesentery located immediately behind SMA and inferior to transverse duodenum – Bowel loop herniates into pocket of ascending mesocolon • Associated abnormalities ○ Right-sided paraduodenal hernias often associated with intestinal nonrotation

Presentation • Most common signs/symptoms ○ Smaller hernias clinically silent and reduce spontaneously ○ Larger hernias can produce vague discomfort, abdominal distension, periumbilical colicky pain, palpable mass, and localized tenderness – Nonspecific symptoms make clinical diagnosis virtually impossible, making role of imaging critical ○ Both right and left paraduodenal hernias may present with postprandial pain, often with symptoms present (in retrospect) since childhood ○ May present with symptoms of bowel obstruction (nausea, vomiting, abdominal pain, distension)

Demographics • Age ○ All ages, but most common between 4th and 6th decades • Gender ○ M:F = 3:1 • Epidemiology ○ Most common subtype of internal hernia, accounting for > 50% of all internal hernias ○ Usually congenital and only rarely acquired due to surgery or trauma ○ Rare cause of SBO, accounting for only 0.5 - 4.1% of all small bowel obstructions ○ Very high (~ 50%) lifetime risk of strangulation or incarceration

Natural History & Prognosis • Complications ○ Volvulus, ischemia, strangulation ○ Bowel gangrene, shock, death • Good prognosis with early surgical correction, but risk of poor outcomes in patients who present with bowel obstruction and other complications

Staging, Grading, & Classification

Treatment

• Hernias classified based on anatomic location ○ Internal or intraabdominal: Herniation of bowel loops via defect within abdominal cavity ○ External: Prolapse of bowel loops via defect in wall of abdomen or pelvis ○ Diaphragmatic: Protrusion of bowel loops via hiatus or congenital defect • Subclassification of internal hernias ○ Paraduodenal hernia ○ Transmesenteric postoperative hernia ○ Foramen of Winslow, pericecal hernias ○ Intersigmoid and transomental hernias • Subclassification of paraduodenal hernias based on location ○ Left (75%), right (25%)

• All paraduodenal hernias should be surgically repaired (with closure of mesenteric defect) ○ Most often performed with open laparotomy, although laparoscopic approach may be possible

Gross Pathologic & Surgical Features • Dilated bowel loops herniating via mesenteric defect

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CLINICAL ISSUES

DIAGNOSTIC CHECKLIST Consider • Consider incarceration with ischemia if bowel loops within hernia appear thickened or abnormally enhancing

Image Interpretation Pearls • Cluster of dilated SB loops lateral to ascending/descending duodenum with crowded/twisted mesenteric vessels

SELECTED REFERENCES 1.

Liao YH et al: Right paraduodenal hernia: characteristic MDCT findings. Abdom Imaging. 36(2):130-3, 2011

Paraduodenal Hernia Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial NECT demonstrates a cluster of encapsulated small bowel in the left abdomen. Notice the location of these loops, immediately adjacent to the distal duodenum, posterior wall of the stomach, and colon, in keeping with a paraduodenal hernia. (Right) Axial CECT demonstrates a cluster of mildly dilated small bowel loops in the left upper quadrant, displacing the stomach forward. Mesenteric vessels supplying the herniated bowel segments converge toward the center of the cluster.

(Left) Axial CECT shows an oval cluster of jejunum in the left upper quadrant. Note the sharply defined outer margin of the peritoneal sac around the herniated bowel, and the mesenteric vessels converging toward the sac center, compatible with a left paraduodenal hernia. (Right) Delayed film from an upper GI series in the same patient shows a tight cluster of dilated jejunum and delayed passage of contrast to the normal caliber distal small bowel.

(Left) Axial CECT shows a right paraduodenal hernia causing small bowel obstruction. Note the U-shaped configuration of the bowel loop within the right paraduodenal hernia sac . (Right) Coronal CECT demonstrates the characteristic "encapsulated" morphology of a left paraduodenal hernia . Note the engorged mesenteric vessels extending directly into the hernia sac.

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Transmesenteric Postoperative Hernia KEY FACTS

TERMINOLOGY

PATHOLOGY

• Protrusion of bowel loops through acquired or congenital abdominal mesenteric defect

• Usually related to prior abdominal surgery in adults ○ Most commonly Roux-en-Y gastric bypass and liver transplantation ○ Much more common when Roux loop is placed in retrocolic position • Almost always congenital in children ○ May be secondary to prenatal intestinal ischemia with thinning of mesenteric leaves

IMAGING • Small bowel obstruction with dilated bowel loops and discrete transition point from dilated to nondilated bowel • Clustered loops of small bowel in periphery of abdominal cavity • Displaced overlying omental fat of herniated bowel loop, with bowel loops directly contacting abdominal wall • Bowel loops found lateral to colon (unlike normal appearance, where colon is lateral to small bowel) • Hernia usually not encapsulated or enveloped in sac • Most often occurs in the right hemiabdomen

TOP DIFFERENTIAL DIAGNOSES • Closed loop bowel obstruction • Paraduodenal or pericecal internal hernia with obstruction

(Left) Axial graphic shows dilated small bowel herniating through a mesenteric defect . Note the peripheral position of the small bowel , medial displacement of the colon , and the displaced mesenteric vessels . (Right) Axial CECT in a patient with prior colonic resection shows a cluster of dilated small bowel in the left abdomen. These loops lie ventral to the transverse colon , and the mesenteric vessels are distorted and congested. These findings are typical of a transmesenteric hernia.

(Left) Axial CECT in a patient with a history of prior abdominal surgery demonstrates multiple dilated, fecalized loops of small bowel in the left abdomen, in keeping with a small bowel obstruction. (Right) Coronal CECT in the same patient demonstrates that these bowel loops are clustered in the lateral aspect of the abdomen, directly abutting the abdominal wall, and displacing the colon . This constellation of findings is classic for a postoperative transmesenteric hernia.

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CLINICAL ISSUES • Larger transmesenteric hernias present with symptoms of small bowel obstruction ○ Symptoms are more likely to be acute compared to other types of internal hernias ○ High risk of volvulus (~ 30%) and ischemia (~ 40%) ○ Onset usually months after original surgery • Treatment: Laparotomy with bowel decompression and surgical correction of mesenteric defect

Transmesenteric Postoperative Hernia

Definitions • Protrusion of bowel loops through acquired or congenital abdominal mesenteric defect

IMAGING General Features • Best diagnostic clue ○ Small bowel obstruction in patient status post liver transplant or Roux-en-Y surgery with dilated bowel loops abnormally clustered at periphery of abdomen • Location ○ Abnormal opening in mesentery of small bowel or colon – Most commonly found in right mid abdomen ○ Postoperative hernias from Roux-en-Y gastric bypass surgery occur in 3 primary locations – Transverse mesocolon (80%) – Small bowel mesentery (14%) – Behind Roux loop (6%) (Peterson-type hernia) ○ Hernias after liver transplant can occur in transverse mesocolon (more common) or small bowel mesentery • Size ○ Mesenteric defect varies from few mm to few cm

Radiographic Findings • Radiography ○ "Closed loop" obstruction: Markedly distended segment of small bowel with multiple air-fluid levels ○ Crowded and dilated small bowel loops in abnormal location (often towards periphery of abdomen)

CT Findings • Small bowel obstruction with dilated small bowel loops and discrete transition point from dilated to nondilated bowel and distally decompressed small bowel loops • Clustered, tethered loops of small bowel in periphery of abdominal cavity immediately adjacent to abdominal wall ○ Bowel loops found lateral to colon unlike normal appearance, where colon is lateral to small bowel ○ Displacement of overlying omental fat of herniated bowel loop, with obstructed bowel loops directly contacting abdominal wall ○ Colon displaced posteriorly and inferiorly (most common) or medially (less common) ○ Right or left displacement of main mesenteric trunk with stretching and tethering of more distal mesenteric vascular branches ○ Most often occurs in right hemiabdomen ○ Hernia usually not encapsulated or enveloped in sac unlike paraduodenal hernias • Additional findings often suggestive of closed loop obstruction or volvulus ○ Whirl sign (small bowel volvulus with twisting of mesenteric vessels around a central point) ○ Mesenteric vessels appear engorged, crowded, or twisted ○ Thickened bowel wall and ascites, particularly in cases with bowel ischemia • Smaller transmesenteric hernias after Roux-en-Y gastric bypass via transverse mesocolon

○ Small retrogastric cluster of small bowel loops with mass effect on posterior stomach wall – Redundant dilated Roux loop – No colon or fat displacement

Fluoroscopic Findings • Small bowel follow through ○ Crowding of bowel loops in abnormal location at periphery of abdomen (most common on right side of abdomen) ○ Bowel loops do not appear contained in sac or have confining border ○ Varying degrees of small bowel obstruction (SBO) with discrete point of transition between dilated and nondilated bowel ○ Some degree of fixation, stasis, and delayed flow of contrast seen in herniated bowel ○ Lateral films useful to demonstrate displacement of herniated bowel loops

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Closed Loop Bowel Obstruction • Obstruction of small bowel at 2 points in single location forming "closed loop" • Most often due to adhesions, but caused occasionally by internal or external hernia • High risk of bowel infarction, strangulation, and volvulus • Fluid-filled loops of markedly dilated small bowel with tethered, clumped configuration ○ Dilated bowel loops and stretched mesenteric vessels appear to radiate towards a central point • May be indistinguishable from transmesenteric hernia, especially if associated with volvulus

Paraduodenal Internal Hernia With Obstruction • Cluster of dilated small bowel loops in right or left (most common) upper abdomen that appear encapsulated • Presence of encapsulation is key feature to differentiate from transmesenteric hernia

Pericecal Internal Hernia With Obstruction • Herniation of small bowel through defect in cecal mesentery • Cluster of small bowel loops lies posterior and lateral to cecum with extension into right paracolic gutter • No history of prior surgery and lies in right lower quadrant (transmesenteric hernias more common in right upper quadrant)

PATHOLOGY General Features • Etiology ○ Pathogenesis and mechanism – Abnormal spaces or defects created in abdominal mesentery due to prior abdominal surgery or developmental mesenteric anomalies

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Transmesenteric Postoperative Hernia

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□ Abnormal mesenteric fixation or defects may lead to abnormal mobility of small bowel, facilitating herniation of small bowel loops (jejunum/ileum) □ Defect may enlarge over time due to repeated herniation or rapid weight loss in bariatric surgery patients □ Herniation of bowel loops may be transient or intermittent ○ Transmesenteric postoperative hernia – Mesenteric hernias in adults are almost always related to prior abdominal surgery □ Defect in mesentery either due to failure to close mesenteric defect during surgery or breakdown of closure – Most commonly Roux-en-Y gastric bypass and liver transplantation, but can be associated with any small or large bowel surgery □ Much more common when Roux loop is placed in retrocolic position (extending inferiorly behind transverse colon) □ Much less common when Roux loop is placed in antecolic position (extending anteriorly to transverse colon), as no defect is created in transverse mesocolon □ More common with laparoscopic procedures than open surgery ○ Transmesenteric congenital hernia – Mesenteric hernias in children are almost always congenital – Mesenteric defect (usually 2-5 cm in diameter) located close to ligament of Treitz or ileocecal valve – Cause unknown, but may be secondary to prenatal intestinal ischemia with associated thinning of mesenteric leaves

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Smaller hernias may be clinically silent ○ Larger hernias present with symptoms of SBO – Vague discomfort, periumbilical pain, abdominal distension, palpable mass, nausea, and vomiting ○ Symptoms can be chronic and recurrent (low grade) or acute (high grade), although more likely to be acute compared to other types of internal hernias ○ Onset usually months after original surgery (mean 235 days after surgery) – SBO in 1st month after surgery is much more likely due to adhesions

Demographics • Age ○ Bimodal distribution, occurring in both adults and children – Most common internal hernia in children □ Congenital defect in small bowel mesentery (usually near ligament of Treitz or ileocecal region) – Usually iatrogenic in adults: Transmesenteric postoperative hernias □ Usually obese adults who have had Roux-en-Y gastric bypass □ Typically between 4th and 6th decades • Gender ○ M liver > small bowel > stomach ○ Hernias in adults usually contain omental fat; involvement of bowel or liver more likely in children

○ With pericardial defect, hernia sac may protrude into pericardial cavity or heart may protrude downwards

TOP DIFFERENTIAL DIAGNOSES • Pericardial fat pad • Mediastinal and thoracic masses • Pulmonary parenchymal lesions

CLINICAL ISSUES • Rare, 3-4% of all diaphragmatic hernias • Most cases are diagnosed in adults • Often asymptomatic in adults, and more likely symptomatic in children ○ Symptoms often include chronic GI complaints ○ Rarely acute symptoms due to incarceration, strangulation, obstruction, or volvulus • Surgical repair in symptomatic patients via thoracotomy, laparotomy, or laparoscopic approach • Surgical repair in asymptomatic patients more controversial

Peritoneum, Mesentery, and Abdominal Wall

KEY FACTS

(Left) Frontal radiograph shows a large, relatively lucent mass in the right costophrenic angle. (Right) Axial NECT in the same patient shows that the opacity on the radiograph corresponds to a fat-containing mass in the right cardiophrenic angle.

(Left) Sagittal NECT in the same patient shows that the previously visualized fatty mass actually represents a Morgagni hernia with omental fat herniating into the chest. Notice the discrete defect in the diaphragm and the numerous small omental vessels extending upwards into the hernia sac. (Right) Coronal NECT in the same patient again demonstrates the Morgagni hernia with a discrete diaphragmatic defect and omental fat herniating into the chest.

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Portal Hypertension and Varices KEY FACTS

TERMINOLOGY • Portal hypertension: Elevated portal pressures due to resistance to portal blood flow

IMAGING • Imaging features of portal hypertension ○ Ascites: Fluid in dependent recesses of peritoneal cavity ○ Splenomegaly: Spleen is enlarged > 500 cc ○ Varices: Well-defined, tubular or serpentine collateral vessels with same enhancement as adjacent veins ○ Mesenteric edema: attenuation of mesenteric fat ○ Dilation of mesenteric veins: Portal vein > 13 mm ○ Slow or reversed flow in portal veins on ultrasound – Slow flow in portal vein (< 15 cm/sec) – Portal flow may be biphasic or completely reversed – risk of portal vein thrombosis ○ Portal gastropathy, enteropathy, and colopathy – May manifest as thickening of colon (especially right colon), small bowel, and stomach

(Left) Graphic shows esophageal varices as serpiginous, longitudinally oriented submucosal venous collaterals extending into the gastric fundus. (Right) Esophagram performed after endoscopic sclerosis of varices shows defects in the esophageal wall. Varices are usually pliable and easily compressed. Varicoid carcinoma could have a similar appearance.

(Left) Coronal CECT demonstrates multiple varices in the left upper quadrant in communication with the splenic vein and the left renal vein , which appears dilated, forming a splenorenal shunt. (Right) Coronal CECT in a patient with cirrhosis and portal hypertension demonstrates thrombus in the portal and superior mesenteric veins, with calcification suggesting chronicity. Portal hypertension increases the risk of portal vein thrombus due to stasis and slow flow.

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○ Gallbladder wall thickening

PATHOLOGY • Causes of portal hypertension divided into 3 categories ○ Pre sinusoidal: Portal vein/splenic vein thrombosis ○ Sinusoidal: Cirrhosis (most common), extensive hepatic tumor, or any severe hepatocellular disorder ○ Post sinusoidal: Right-sided heart failure, constrictive pericarditis, Budd-Chiari syndrome • Varices (portosystemic collaterals) develop when portal pressures increase beyond critical value ○ Blood in portal venous system bypasses liver and empties into systemic veins via portosystemic collaterals

CLINICAL ISSUES • Asymptomatic until varices rupture or ascites are infected • 30% of patients with esophageal varices experience variceal hemorrhage within 2 years of diagnosis • Many patients with cirrhotic ascites develop spontaneous bacterial (or rarely tuberculous) peritonitis

Portal Hypertension and Varices

Definitions • Portal hypertension: Elevated portal pressures due to resistance to portal flow, defined as absolute portal venous pressure of > 10 mm Hg or gradient between portal and systemic veins of > 5 mm Hg • Varices: Abnormally dilated and tortuous veins due to rerouting of blood flow away from liver into lower pressure systemic veins through collateral pathways

IMAGING General Features • Common features of portal hypertension ○ Ascites: Water density fluid in dependent recesses of peritoneal cavity ○ Splenomegaly: Spleen is enlarged > 500 cc – Usual upper limits: 13 cm in length and 6 x 8 cm in width and breadth, respectively ○ Varices: Well-defined, tubular or serpentine portosystemic collateral vessels with same enhancement as adjacent veins – Usually opacify on venous phase images (not on arterial phase) ○ Mesenteric edema: Stranding and increased attenuation in mesenteric fat ○ Dilation of mesenteric veins (portal vein, superior mesenteric vein, and splenic vein) – Portal vein is often dilated > 13 mm ○ Slow or reversed flow in portal veins on Doppler ultrasound – Normal portal vein flow is hepatopetal (toward liver) with normal flow velocity of 15-40 cm/sec – As portal hypertension progresses, portal blood flow velocities decrease – Eventually, portal flow may be biphasic (alternating hepatopetal/hepatofugal flow) or completely reversed – Stasis of blood flow in portal vein as well as hypercoagulability due to intrinsic liver disease increases risk of portal vein thrombosis ○ Portal gastropathy, enteropathy, and colopathy – May manifest as thickening of colon (especially right colon), small bowel, and stomach ○ Gallbladder wall thickening: Due to combination of portal hypertension, hepatocellular dysfunction, and hypoproteinemia • Varices: Types or locations ○ Left gastric venous collateral vessels – Vascular channels in triangular fatty tissue between medial wall of upper gastric body and posterior margin of left hepatic lobe in lesser omentum – Coronary (left gastric) vein 5-6 mm in diameter is considered abnormal – Usually accompanied by esophageal or paraesophageal varices ○ Esophageal varices – Dilated tortuous submucosal venous plexus of esophagus can be divided into "uphill" and "downhill" varices

□ Uphill varices (collateral blood flow into superior vena cava (SVC) from portal vein via azygous vein): Result from portal hypertension and found in distal 1/2 of esophagus □ Downhill varices (collateral flow from SVC into inferior vena cava [IVC] or portal system): Usually due to SVC obstruction and found in proximal 1/3 of esophagus – Tortuous or serpiginous longitudinal filling defects on esophagography □ Varices may collapse during esophageal peristalsis or with distention of lumen □ Best detected when esophagus is collapsed and esophageal mucosa coated with thick barium – CECT has limited sensitivity for small esophageal varices, which may not be evident when collapsed – Endoscopy is most sensitive diagnostic tool ○ Paraesophageal varices – Collateral vessels in posterior mediastinum behind esophageal wall connect coronary vein with azygos and hemiazygos veins and vertebral plexus ○ Recanalized paraumbilical vein – Dilated collateral vein ( 3 mm) arising from left portal vein and coursing between medial and lateral segments of left hepatic lobe in anterior edge of falciform ligament – Presence is virtually diagnostic of portal hypertension ○ Abdominal wall varices – Prominent collateral veins radiating from umbilicus referred to as "caput medusae" (head of Medusa, a mythological figure who had snakes for hair) – Connect with superior and inferior epigastric veins and fed by paraumbilical and omental veins ○ Perisplenic varices – Dilated veins in anteroinferior aspect of spleen traversing splenocolic ligament – May lead to spontaneous splenorenal shunt (communication between left renal vein and splenic vein) ○ Retrogastric varices – Dilated veins in posterior or posteromedial aspect of gastric fundus near cardia – Fed by coronary (left gastric) vein or gastroepiploic vein; drain into esophageal or paraesophageal veins – Can mimic tumors on NECT, barium study, or endoscopy ○ Omental varices – Small and numerous varices throughout greater omentum – Should not be mistaken for metastases or granulomas ○ Retroperitoneal-paravertebral varices – Arise from colic or mesenteric branches ○ Mesenteric varices – Dilated and tortuous branches of superior mesenteric vein in leaves of mesentery ± bowel wall – Can be cause of lower GI bleeding ○ Varices may develop in sites of previous abdominal surgery or intraabdominal inflammation – e.g., peristomal varices surrounding ostomy in patient with cirrhosis following colectomy • Ascites

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

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Portal Hypertension and Varices ○ Cirrhosis present in 80-85% of cases ○ Ascites should have near-water attenuation on CT – Rarely mildly hyperdense due to prior episodes of infection or hemorrhage ○ Anechoic on ultrasound unless complicated ○ Accumulates in dependent recesses of peritoneal cavity – Morison pouch, subphrenic spaces, paracolic gutters, and pelvis

Imaging Recommendations • Best imaging tool ○ CECT is best study to identify varices and other manifestations of portal hypertension

DIFFERENTIAL DIAGNOSIS Esophageal Carcinoma • Varicoid carcinoma: Serpiginous filling defects in submucosa that are fixed and unchanged with peristalsis • Can be simulated by sclerosed or thrombosed varices

Gastric Carcinoma

CLINICAL ISSUES Presentation

• Obstruction of SVC results in downhill varices as collaterals follow esophagus and azygous-hemiazygos system

• Most common signs/symptoms ○ May be asymptomatic in mild cases ○ Hematemesis or melena due to bleeding from esophageal or gastric varices ○ Abdominal distension due to accumulation of ascites ○ Abdominal pain, fever, and WBC due to spontaneous bacterial peritonitis ○ Altered mental status due to hepatic encephalopathy

Other Cause of Ascites

Natural History & Prognosis

• Congestive heart failure (cardiac ascites), peritonitis, peritoneal carcinomatosis, renal failure (especially nephrotic syndrome), pancreatitis, peritoneal dialysis, etc.

• 30% of patients with esophageal varices experience variceal hemorrhage within 2 years of diagnosis ○ Most serious complication of portal hypertension (2035% of all deaths in cirrhotic patients) ○ Mortality rate is 40-70% within 6 weeks ○ Highest risk for variceal bleeding is in patients with portosystemic gradient of > 12 mm Hg • Many patients with cirrhotic ascites develop spontaneous bacterial (or rarely tuberculous) peritonitis ○ Diagnosis may not be evident (often causes new onset of encephalopathy, pain, fever) ○ Early diagnosis and antibiotic treatment are essential

• Gastric masses may be simulated by gastric varices on either NECT or fluoroscopic barium studies • Distinction readily made on CECT, which shows characteristic morphology and enhancement of varices

Superior Vena Cava Obstruction

Other Causes of Gastrointestinal Bleeding • Not always due to variceal hemorrhage in cirrhotic patients • Other etiologies include gastritis, gastric ulcers, and Mallory-Weiss tear of distal esophagus

PATHOLOGY General Features • Etiology ○ Causes of portal hypertension are divided into 3 categories – Pre sinusoidal: Portal vein thrombosis, splenic vein thrombosis, compression of portal vein by tumor or lymphadenopathy, schistosomiasis – Sinusoidal: Cirrhosis (most common cause: ~ 80% of cases), extensive hepatic tumor (metastases, hepatocellular carcinoma), or any other severe hepatocellular disorder – Post sinusoidal: Right-sided heart failure, constrictive pericarditis, tricuspid insufficiency, Budd-Chiari syndrome, hepatic veno-occlusive disease ○ Varices begin to develop when portal pressures increase beyond critical value – Result from dilation of embryonic channels or redirection of flow within existing veins ○ Blood flow always seeks path of least resistance and lowest pressure 116

– When portal hypertension is severe, blood flows away from liver (hepatofugal flow) – Blood in portal venous system will bypass liver and empty into adjacent systemic veins via portosystemic collaterals – Coronary venous collateral vessels are most common varices in portal hypertension (80%) – Esophageal varices are most important clinically due to risk of bleeding ○ Ascites pathophysiology – Portal hypertension increased nitric oxide renal sodium retention vasodilation increased intravascular volume ascites – Loss of intravascular fluid to ascites stimulates sympathetic nervous activity and more secretion of renin and aldosterone □ Leads to more sodium retention and more ascites

Treatment • Primary goal is to prevent/treat symptomatic complications ○ Dietary sodium restriction, spironolactone, and diuretics to prevent ascites – Regular paracentesis for symptomatic relief ○ -blockers and obliteration of varices (endoscopic sclerotherapy, endoscopic variceal ligation, surgical devascularization) to prevent bleeding ○ Transjugular intrahepatic portosystemic shunt (TIPS) or surgical portosystemic shunts to reduce portal pressures in patients with intractable ascites or variceal bleeding

SELECTED REFERENCES 1.

Lee JY et al: Clinically Severe Portal Hypertension: Role of Multi-detector Row CT Features in Diagnosis. Dig Dis Sci. 59(9):2333-43, 2014

Portal Hypertension and Varices Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT in a cirrhotic patient demonstrates a recanalized paraumbilical vein in communication with the left portal vein , a virtually pathognomonic finding for portal hypertension. Note the multiple periumbilical collaterals forming a caput medusae. (Right) Sagittal volume-rendered CECT nicely demonstrates the direct communication between a recanalized paraumbilical vein and multiple abdominal wall varices .

(Left) Coronal volumerendered CECT demonstrates extensive varices surrounding the rectum in a cirrhotic patient. While often asymptomatic, rectal varices (like varices elsewhere) can bleed and result in gastrointestinal hemorrhage. (Right) Axial CECT demonstrates multiple large gastric varices in the left upper quadrant. Although the diagnosis is straightforward on these venous phase images, the varices could mimic an intramural mass on NECT or arterial phase CECT images.

(Left) Axial CECT in a middleaged man with ulcerative colitis and primary sclerosing cholangitis shows a descending colostomy and large varices around the stoma. Surgical creation of the stoma creates a new site of portosystemic anastomosis and a potential site for the development of varices. (Right) Axial CECT demonstrates large varices surrounding the esophagus . Paraesophageal varices are not infrequently mistaken for a mediastinal mass on either CXR or NECT.

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Traumatic Abdominal Wall Hernia KEY FACTS

TERMINOLOGY • Traumatic disruption of musculature and fascia of anterior abdominal wall due to blunt trauma

IMAGING • Roughly 75% occur in lower abdomen • Common locations include iliac crest region in seat belt injuries and lower abdomen (lateral to rectus sheath or inguinal region)

PATHOLOGY • Most hernias develop due to combination of sudden increase in intraabdominal pressure, direct force of traumatic impact, acceleration-deceleration shear injury, and compressive force of seat belt ○ High-energy injuries: Motor vehicle accidents constitute ~ 50% of cases, with seat belts increasing risk – "High-riding" seat belt incorrectly placed over abdomen increases risk (muscle avulsion from iliac crest)

(Left) Axial CECT demonstrates small bowel and colon herniating through a traumatic abdominal wall defect. At surgery, several segments of small bowel had serosal tears and avulsions, requiring resection. (Right) Axial CECT demonstrates a traumatic lumbar hernia, with herniated abdominal fat covered only by the latissimus dorsi muscle . Also noted is infiltration of the intraabdominal fat adjacent to the hernia. At surgery, a serosal tear of the descending colon was identified.

(Left) Axial CECT demonstrates a large amount of hypoenhancing small bowel herniated through a traumatic hernia of the right abdominal wall. Active arterial bleeding is evident. Much of the herniated bowel was not viable at the time of surgery. (Right) Axial CECT shows disruption of the abdominal wall muscles in the left lower quadrant, with the muscles avulsed from their attachment to the iliac crest. Note the presence of adjacent subcutaneous hematoma . This is a typical example of a seat belt injury.

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– Other traumatic injuries are common (~ 80%), with up to 50% of patients suffering other abdominal injuries requiring surgery ○ Low-energy injuries (most common in children): Impact by small blunt object (such as bicycle handlebar, i.e., handlebar hernia)

CLINICAL ISSUES • May be overlooked clinically at time of injury and often diagnosed due to hernia-related complications ○ Complications: Incarceration; bowel strangulation, perforation, and ischemia • Peak incidence in children < 10 years of age due to handlebar injuries ○ 2nd most common age group is 20-50 years due to motor vehicle accidents • Treatment: Delayed repair of hernia usually performed 6-8 weeks following high-energy injuries to allow primary tissue damage to subside

Traumatic Abdominal Wall Hernia

Abbreviations • Traumatic abdominal wall hernia (TAWH)

Definitions • Traumatic disruption of musculature and fascia of anterior abdominal wall due to blunt trauma (in absence of penetrating injury) ± herniation of bowel or visceral organs into subcutaneous space • Handlebar hernia: Localized abdominal wall hernia caused by handlebar (or similar) injury

IMAGING General Features • Best diagnostic clue ○ Development of new abdominal wall hernia in patient with recent blunt trauma (without penetrating injury) • Location ○ Roughly 75% occur in lower abdomen – May reflect inherent weakness of lower abdomen due to natural orifices (such as inguinal canals) and susceptibility to increased intraabdominal pressures ○ Equally common in right and left sides of abdomen ○ Common locations include – Region of iliac crest in seat belt injury (site of lap and shoulder strap junction) – Focal hernias often occur in lower abdomen lateral to rectus sheath or inguinal region – Larger, diffuse abdominal wall defects most often sustained in motor vehicle accidents • Size ○ Anatomical defects vary from small defects (few centimeters) to large disruptions • Morphology ○ All layers of muscle and fascia are usually involved, while skin remains intact

CT Findings • Best modality to demonstrate size of defect, contents of hernia, and concomitant visceral organ injuries

DIFFERENTIAL DIAGNOSIS Other Nontraumatic Hernias • Post-traumatic hernias may have identical appearance to multiple other types of nontraumatic hernias, and key to distinction is clinical history of trauma

PATHOLOGY General Features • Etiology ○ Most hernias develop due to combination of sudden increase in intraabdominal pressure, direct force of traumatic impact, acceleration-deceleration shear injury, and compressive force of seat belt – Force is insufficient to penetrate skin but strong enough to disrupt muscle and fascia ○ High-energy injuries: ~ 50% of cases result from motor vehicle accidents, with seat belts increasing risk

– Shearing force applied across bony prominences (e.g., iliac crest) – "High-riding" seat belt incorrectly placed over abdomen (rather than bony pelvis) increases risk of TAWH (particularly muscle avulsion from iliac crest) □ Obese patients at higher risk for this mechanism ○ Low-energy injuries: Impact by small blunt object – e.g., impaction of bicycle handlebar on abdominal wall (handlebar hernia) – Hernias can develop after relatively minor trauma in children • Associated abnormalities ○ Other traumatic injuries are common (~ 80% of cases), with up to 50% of patients suffering other intraabdominal injuries requiring surgery and 1/3 of patients suffering bone injuries

CLINICAL ISSUES

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Presentation • Abdominal skin ecchymosis or abrasions ("seat belt" ecchymosis)

Demographics • Age ○ Peak incidence < 10 years due to handlebar injuries ○ 2nd most common 20-50 years due to motor vehicle accidents • Epidemiology ○ TAWH uncommon (< 1% of blunt abdominal trauma)

Natural History & Prognosis • May be overlooked at time of injury due to attention focused on concomitant injuries, and often diagnosed due to development of hernia-related complications ○ Only 22% of TAWH patients in 1 series were diagnosed clinically, making CT essential to diagnosis • Complications: Incarceration, bowel strangulation, bowel perforation, and bowel ischemia

Treatment • High-energy injuries: Immediate exploratory laparotomy to treat visceral injuries ○ Delayed repair of hernia can be performed 6-8 weeks following injury to allow primary tissue damage to subside ○ In rare cases, stable patients with only mild intraabdominal injuries may undergo simultaneous repair of hernia during initial exploratory laparotomy • Low-energy injuries: Surgical options include local exploration, incision overlying defect, laparoscopic repair, and open repair

DIAGNOSTIC CHECKLIST Consider • TAWH can be easily missed both on clinical examination and imaging due to presence of concomitant major injuries

SELECTED REFERENCES 1.

Gutteridge I et al: Traumatic abdominal wall herniation: case series review and discussion. ANZ J Surg. 84(3):160-5, 2014

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Traumatic Diaphragmatic Rupture KEY FACTS

IMAGING • 90-98% occur on left side (usually posterolateral diaphragm) • Multiple different CT signs of diaphragmatic injury, each with variable sensitivity and specificity ○ Discontinuity of hemidiaphragm with focal defect (segmental diaphragmatic defect) ○ Dangling diaphragm sign: Free edge of torn diaphragm curls inward on axial images rather than continuing its normal course parallel to chest wall ○ Absent diaphragm sign: Absence of diaphragm in expected location without visualization of discrete tear ○ Herniation of abdominal contents through a discrete diaphragmatic defect ○ Collar sign: Waist-like narrowing of herniated structure as it extends through diaphragmatic tear ○ Fallen or dependent viscus sign: Herniated viscus abuts posterior ribs and thoracic wall without intervening lung

(Left) Chest x-ray in a young man following a motor vehicle crash shows a pneumothorax, chest tube, and an NG tube that is curved up toward the chest. (Right) Axial CT in the same patient shows the typical signs of diaphragmatic injury, including the fallen viscus sign. The stomach lies in the chest. Note that it has "fallen" medially and posteriorly to lie against the posteromedial chest wall. The stomach appears pinched as it traverses the defect in the diaphragm (collar sign).

(Left) Axial CECT shows the stomach in the thorax, and it has "fallen" through the diaphragmatic defect to lie against the posteromedial chest wall. The anterior wall of the stomach directly abuts the lung, and is not confined by the diaphragm. (Right) Coronal CECT in the same patient demonstrates the stomach extending upward through a diaphragmatic defect.

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○ Secondary signs of injury include simultaneous presence of pneumothorax and pneumoperitoneum or hemothorax and hemoperitoneum, active extravasation of contrast in or near diaphragm, or injuries to organs lying near diaphragm

PATHOLOGY • 75% of cases caused by blunt trauma, and 25% caused by penetrating trauma • Strong association with polytrauma and other major traumatic injuries

CLINICAL ISSUES • 1-5% of all patients with substantial blunt abdominal or thoracic trauma • True incidence is likely underestimated, as these injuries may be frequently missed on imaging • Surgical repair of diaphragm indicated for all diaphragmatic injuries, even when small

Traumatic Diaphragmatic Rupture

Synonyms • Traumatic diaphragmatic hernia

IMAGING General Features • Best diagnostic clue ○ Discontinuity of hemidiaphragm with fallen or dependent viscus sign • Location ○ 90-98% occur on left side (usually posterolateral part of diaphragm, medial to spleen) – Left hemidiaphragm has weaker pleuroperitoneal membrane, while right hemidiaphragm is protected by liver • Size ○ Blunt trauma – Most tears are large (> 10 cm in length) ○ Penetrating trauma – Gunshot wounds (blast injuries) large defects in diaphragm – Stab wounds shorter lacerations (usually 1-2 cm) □ More likely to have delayed diagnosis □ Initial short laceration may be overlooked, but will often enlarge over time

CT Findings • Multiple different direct and indirect signs of diaphragmatic injury, each with variable sensitivity and specificity ○ Discontinuity of hemidiaphragm with focal defect (segmental diaphragmatic defect) – Free edge of diaphragm may appear thickened and hypoenhancing due to muscle retraction or hemorrhage ○ Dangling diaphragm sign: Free edge of torn diaphragm curls inward on axial images rather than continuing its normal course parallel to chest wall ○ Absent diaphragm sign: Absence of diaphragm in expected location (without visualization of discrete tear) ○ Herniation of abdominal contents through discrete diaphragmatic defect – Herniated organs: Stomach > omentum, colon, small bowel, spleen, liver ○ Collar sign: Waist-like narrowing of herniated structure as it extends through diaphragmatic tear – Often easier to appreciate on coronal multiplanar reformats – May be associated with hump sign: Unusual contour of liver as it extends through diaphragmatic defect, often with a band-like region of hypoperfusion of liver at base of hernia ○ Fallen or dependent viscus sign: Herniated viscus abuts posterior ribs and thoracic wall without intervening lung ○ Abdominal contents lateral to diaphragm on axial images ○ Secondary signs of injury include simultaneous presence of pneumothorax and pneumoperitoneum or hemothorax and hemoperitoneum, active extravasation of contrast in or near diaphragm, or injuries to organs lying near diaphragm

– Trajectory of penetrating injury can often be surmised from other injuries and ectopic gas, and can increase suspicion for diaphragmatic injury • Diaphragmatic rupture remains difficult diagnosis on CT, with reported sensitivities as low as 73% and specificities as low as 50% ○ Multiplanar reformations are critical to diagnosis, and partially explain superior performance of modern MDCT compared to pre-MDCT technology

MR Findings • Normal diaphragm on T1- and T2WI appears as a continuous hypointense band ○ Diaphragm is generally easier to visualize on MR than on CT, but MR is usually more appropriate for evaluation of stable patient, not in acute trauma setting • Imaging findings parallel those on CT

Radiographic Findings

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

• Radiography ○ Radiographs are significantly less sensitive than CT for diaphragmatic injury, but may often be initial study performed – Nonvisualized or abnormal diaphragmatic contour with abnormally elevated hemidiaphragm contour □ Upper diaphragmatic contour may be elevated > 6 cm above contralateral hemidiaphragm – Presence of lower thoracic soft tissue density mass or gas density suggesting herniated abdominal viscera □ Herniation of hollow viscus (stomach, colon, small bowel with air-fluid levels) should not be confused with loculated hydropneumothorax or vice-versa □ Focal constricted gas-filled bowel loop (collar sign) may be visualized at site of diaphragmatic tear (similar to CT) – Visualization of nasogastric (NG) tube above left hemidiaphragm with abnormal U-shaped course and tip directed back toward left shoulder – Secondary findings include contralateral shift of mediastinum and presence of ipsilateral thoracic injuries (pneumothorax, rib fractures, pulmonary contusion, etc.)

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformations

DIFFERENTIAL DIAGNOSIS Congenital Diaphragmatic Hernias (Bochdalek or Morgagni Hernias) • Bochdalek hernia is a congenital defect in posteromedial diaphragm, while Morgagni hernia is a parasternal defect of anteromedial diaphragm • Key distinction is lack of trauma history or other secondary signs of trauma adjacent to diaphragm

Eventration of Diaphragm • Thinning of diaphragmatic muscle, which still retains its continuity and attachments to costal margin ○ Usually anteromedial aspect of right hemidiaphragm • No evidence of a discrete diaphragmatic defect, collar sign, or fallen viscus sign 121

Peritoneum, Mesentery, and Abdominal Wall

Traumatic Diaphragmatic Rupture

Paralyzed Diaphragm • Properly formed diaphragm that fails to contract, resulting in asymmetric elevation of involved hemidiaphragm • Can occur due to abnormalities of brain, spinal cord, neuromuscular junction, phrenic nerve, or muscle • No evidence of a discrete diaphragmatic defect, collar sign, or fallen viscus sign

Pleural Effusion or Pulmonary/Extrapleural Mass • Can mimic traumatic diaphragmatic hernia on radiographs, but not on CT

PATHOLOGY General Features • Etiology ○ 75% of cases caused by blunt trauma – Most common cause of blunt diaphragmatic injury is motor vehicle collision (MVC) – Other causes include fall from height or crushing blow – Lateral impact more likely to injure diaphragm through shear injury, while frontal impact increases intraabdominal pressures which cause diaphragmatic rupture ○ 25% of cases caused by penetrating trauma – Most often due to gunshot and stab wounds ○ Iatrogenic (surgery near diaphragm) • Associated abnormalities ○ Strong association with polytrauma and other major traumatic injuries (52-100% of cases) – Left-sided blunt diaphragmatic injuries most associated with injuries to spleen – Right-sided blunt diaphragmatic injuries associated with injuries to liver, right kidney, aorta, heart, and bones (pelvis, ribs, spine) ○ Frequently associated thoracic injuries (pneumothorax, rib fractures, pleural effusion)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most commonly dyspnea, upper abdominal pain, and chest pain ○ Physical exam may reveal bowel sounds auscultated in chest, decreased breath sounds on affected side, asymmetry of chest wall, and dullness on percussion ○ Hypotension, tachycardia, and other symptoms of severe polytrauma

Demographics • Age ○ More common in young adults (more often injured in MVC and penetrating injuries) • Gender ○ M > F (due to greater incidence of trauma in males) • Epidemiology ○ 1-5% of all patients with substantial blunt abdominal or thoracic trauma ○ True incidence is likely underestimated, as these injuries may be frequently missed on imaging – Diaphragmatic injuries missed in 7-66% of cases 122

– Right-sided diaphragmatic injuries more likely to be missed

Natural History & Prognosis • Complications ○ Obstruction and ischemia of bowel herniated into chest ○ Torsion, devascularization, and ischemia of herniated solid organs ○ Lung injuries: Laceration with hemopneumothorax, pneumonia, respiratory failure ○ Central venous obstruction due to mass effect from herniated structures ○ Accounts for 5% of all diaphragmatic hernias – 90% of all strangulated diaphragmatic hernias are due to trauma • Prognosis ○ Patients with diaphragmatic injury have high mortality from other severe injuries (12-42%) ○ Early diagnosis and repair: Good prognosis ○ Delayed diagnosis and repair: Poor prognosis – Diagnosis delayed in a large proportion of cases – Initial diaphragmatic injury may be missed, even at surgery, due to attention to life-threatening injuries – In pre-CT era, many or most cases were diagnosed months after initial trauma – Diaphragmatic injuries will not heal spontaneously without treatment – Even if abdominal contents do not herniate into chest immediately, will eventually herniate in most patients due to negative intrapleural pressure (80% within 3 years) □ Positive pressure ventilation in acute setting may prevent herniation into chest and cause injury to be missed – Morbidity and mortality rate: Up to 50% in visceral herniation and strangulation

Treatment • Surgical repair of diaphragm indicated for all diaphragmatic injuries, even when small

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Multiplanar reformations are critical for identification of subtle diaphragmatic injuries • Lung contusion, pneumothorax, effusion, atelectasis, and phrenic nerve palsy can mask a diaphragmatic injury

SELECTED REFERENCES 1.

Dreizin D et al: Evolving concepts in MDCT diagnosis of penetrating diaphragmatic injury. Emerg Radiol. ePub, 2014

Traumatic Diaphragmatic Rupture Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT in a patient following MVC shows the stomach lying too far medial, posterior, and superior, indicating herniation through the diaphragm. This is the fallen viscus sign. (Right) Axial CECT in a patient after a stab wound demonstrates a splenic laceration with hematoma, left hemothorax , and subcutaneous emphysema . The presence of hematoma above and below the left diaphragm was concerning for diaphragmatic injury, subsequently confirmed at surgery.

(Left) Coronal CECT in a trauma patient demonstrates a gap in the left hemidiaphragm with the colon protruding into the thorax. Note the extensive enteric contrast material throughout the left thorax due to colonic perforation. (Right) Coronal T2 MR demonstrates diaphragmatic injury due to surgical error. A tear is seen in the left hemidiaphragm with the stomach herniating into the chest. The diaphragm is identified as a low-signal curvilinear structure with a central gap.

(Left) Axial CECT in a trauma patient demonstrates that the stomach is "pinched" as it traverses a defect in the left diaphragm. Another sign of diaphragmatic rupture is the presence of abdominal fat outside the confines of the diaphragm (therefore, in the thorax). (Right) Coronal CECT in the same patient demonstrates how coronal reformations help to visualize the diaphragmatic defect .

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Peritoneum, Mesentery, and Abdominal Wall

Postoperative State, Abdomen KEY FACTS

TERMINOLOGY • Presence of intraperitoneal or body wall gas/fluid following surgery

IMAGING • Pneumoperitoneum is a common imaging finding after surgery on both plain radiographs and CT ○ CT has 2x the sensitivity of plain films for detection of pneumoperitoneum ○ Pneumoperitoneum is seen on CT in 87% of patients following uncomplicated laparotomy at 3 days post surgery and 50% of patients at 6 days ○ No upper limit to normal persistence of pneumoperitoneum, but gas resolves in most patients within 1 week ○ Pneumoperitoneum more likely to persist in patients who have had prior surgery or peritonitis, have undergone open (rather than laparoscopic) surgery, or who have surgical drains

(Left) Axial NECT in a patient after surgery shows skin staples in the anterior abdominal wall, with evidence of free air and perihepatic free fluid . The patient was free of symptoms of infection or bowel leak and recovered without incident. (Right) Axial NECT in a patient after sigmoid colectomy demonstrates large amounts of free intraperitoneal gas , much more than would be normally expected after surgery. Large free air after surgery must raise concern for an anastomotic leak or perforation.

(Left) NECT in the same patient after administration of rectal enteric contrast demonstrates a leak of contrast media at the sigmoid anastomotic staple line . (Right) Axial CECT in a patient with a recent hysterectomy shows a thin, encapsulated collection of gas and fluid in the abdominal wall musculofascial plane at the incision site. Needle aspiration of the collection revealed no evidence of infection, and the collection resolved.

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○ Volume of postoperative pneumoperitoneum is normally small (< 10 cc) in most patients ○ Large or massive pneumoperitoneum is not a normal finding, even in immediate postoperative setting – Presence of massive pneumoperitoneum should raise concern for anastomotic leak or hollow viscus perforation • Free intraperitoneal fluid is present in nearly all patients following open laparotomy or laparoscopy ○ Small, nonloculated collections without enhancing wall or mass effect are of little concern ○ Large volume free fluid or collection with mass effect, enhancing rim, or internal gas should raise concern for infected fluid collection or bowel/anastomotic leak • Extraperitoneal collections (e.g., retroperitoneal and abdominal wall collections) of gas and fluid take longer to resolve than peritoneal air/fluid ○ Peritoneum is much better absorptive surface than granulation tissue, fat, or muscle

Postoperative State, Abdomen

Radiographic Findings

Ultrasonographic Findings

• Plain radiographs may show evidence of free intraperitoneal gas (air) ○ Upright chest x-ray or left lateral decubitus position is most sensitive ○ Requires horizontal x-ray beam centered on most nondependent position of peritoneal cavity – Gas under diaphragm on upright chest film – Gas lateral to liver or medial to iliac crest on decubitus film ○ Requires minimum of several minutes for air to equilibrate (move into antidependent position) ○ Radiographically detectable pneumoperitoneum is seen in 30-77% of patients soon after surgery – Falls to average of 38% by day 3 and 17% by day 7

• Has been shown to detect free air about as well as plain films but not as well as CT ○ Echogenic foci with ring-down artifact (dirty shadow) ○ Up against anterior abdominal wall in supine patient

Definitions • Presence of intraperitoneal or body wall gas/fluid following surgery

IMAGING General Features • Patients who have had prior surgery or peritonitis seem to resorb free air and fluid less readily than those with normal peritoneal cavity • Patients with surgical drains may have a greater incidence of persistent free air (possibly introduced through drain) • Persistent pneumoperitoneum is less likely after laparoscopic procedures compared to open procedures ○ Carbon dioxide is absorbed more readily than room air ○ Pig model showed persistent free air on CT at 2 days after laparoscopy and 6 days after open laparotomy • Some older sources have suggested free air may resorb more quickly in obese patients, at least on plain films ○ More likely that plain films fail to detect small amounts of free air in obese patients ○ CT shows similar prevalence of persistent free air in both obese and thin patients

Imaging Recommendations

CT Findings • CT detects free air with 2x the sensitivity of plain films in studies comparing CT and plain films in same patients ○ Pneumoperitoneum was seen on CT in 87% of patients following uncomplicated laparotomy at 3 days post surgery and 50% of patients at 6 days – Plain film detection was 53% at 3 days and 18% (1 patient) at 6 days ○ No upper limit to normal persistence of pneumoperitoneum, but gas resolves in most patients within 1 week – CT evidence of persistent pneumoperitoneum in 44% up to 3 days post surgery and 30% between 4 and 18 days post surgery – Reports of persistent pneumoperitoneum 8 weeks after colectomy

Peritoneum, Mesentery, and Abdominal Wall

• Best imaging tool ○ CT

○ Frequent sites of collection on supine CT exam – Subphrenic spaces (right > left) – Abutting anterior abdominal wall □ Between or along rectus muscles, which form concave recesses pointed downward – Between mesenteric leaves ○ Most patients have < 10 mL of free air – Volumes up to 40 mL have been documented • Large or massive pneumoperitoneum is not a normal finding, even in immediate postoperative setting ○ Presence of massive pneumoperitoneum should raise concern for anastomotic leak or hollow viscus perforation • Free intraperitoneal fluid is present in nearly all patients following open laparotomy or laparoscopy ○ Small, nonloculated collections without enhancing wall or mass effect are of little concern ○ Large-volume free fluid collection or collections with mass effect, enhancing rim, or internal gas should raise concern for infected fluid collection or bowel/anastomotic leak • Extraperitoneal collections (e.g., retroperitoneal and abdominal wall collections) of gas and fluid take longer to resolve ○ Fluid and gas may persist for many days (much longer than equivalent amount of intraperitoneal gas or fluid) ○ Peritoneum is much better absorptive surface than granulation tissue, fat, or muscle

TERMINOLOGY

CLINICAL ISSUES Natural History & Prognosis • Significance of persistent free intra- or extraperitoneal gas and fluid largely determined by clinical condition of patient ○ Persistent fever, leukocytosis, or signs of peritonitis increase likelihood of postoperative infection or clinically significant gas leak from bowel ○ Presence of large amounts of gas or fluid raises concern, especially if increasing over time after surgery ○ Presence of loculation, mass effect, or rim enhancement of fluid collection raises concern

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Presence of large or increasing pneumoperitoneum after surgery is an abnormal finding that should raise concern for perforation or anastomotic leak

SELECTED REFERENCES 1.

Peirce GS et al: Postoperative pneumoperitoneum on computed tomography: is the operation to blame? Am J Surg. ePub, 2014

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Incision and Injection Sites KEY FACTS

IMAGING • Injection site fluid or gas collection ○ Usually result from injection of subcutaneous heparin, self-injection of insulin, etc. ○ Low-density nodules associated with ectopic gas or fluid • Injection or incision site hematoma or seroma ○ May be misinterpreted as neoplasm but should resolve over time • Injection or incision site abscess ○ Suspicious imaging features include peripheral enhancement, surrounding soft tissue edema and stranding (i.e., cellulitis), and internal ectopic gas • Diabetic lipodystrophy ○ Insulin-dependent diabetic patients may develop atrophy or hypertrophy of fat at injection sites • Keloid (hypertrophic scar) ○ Benign fibrotic scar tissue or soft tissue overgrowth at site of healed skin injury (i.e., incisional scar)

(Left) Plain film radiograph shows rounded calcifications that overlap the lower abdomen. Some of these are lateral to the descending colon and close to the skin, establishing their extraabdominal location. (Right) Axial NECT in the same patient shows heavily calcified injection sites in the subcutaneous tissues over the buttocks. Renal failure may have contributed to the deposition of so much calcium in these lesions.

(Left) Axial CECT shows a heavily calcified or ossified upper abdominal incision site immediately caudal to the xiphoid process. (Right) Coronal CECT in another patient shows a long ossification (over 10 cm) of the midline incision site . The appearance is very similar to that of a rib, with both the cortex and medulla clearly seen.

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○ No clear distinguishing imaging features • Calcified or ossified scar ○ Abdominal incision may develop cartilaginous, osseous, or myelogenous (bone marrow) elements • Endometrial implantation in abdominal incision ○ Most often seen after cesarean section (80% of cases) ○ Cyclical pain at incision site with menstruation ○ Lesions appear solid and irregularly shaped/spiculated on CT or MR with moderate enhancement • Tumor implantation in incision sites ○ Probably more common after laparoscopic surgery ○ Nonspecific imaging appearance, with soft tissue density mass near or within incision site • Injection granulomas ○ Sequelae of subcutaneous injection of drugs resulting in local fat necrosis, scarring, and calcification ○ Usually rounded or linear soft tissue or calcific density lesion seen in subcutaneous fat of buttocks

Abdominal Incision and Injection Sites

Definitions • Lesions in abdominal wall at either incision or injection sites that may be mistaken for other pathologic conditions

IMAGING

□ Absorption of insulin at these sites is erratic □ Nurses caring for diabetic patients are very familiar with this and should encourage patients to change injection sites frequently to avoid this problem • Imaging appearance: Mixed fatty mass in subcutaneous soft tissues on CT or MR ○ Rarely requires imaging (easily recognized clinically)

Imaging Recommendations

Keloid (Hypertrophic Scar)

• Best imaging tool ○ CT

• Benign fibrotic scar tissue or soft tissue overgrowth at site of healed skin injury (i.e., incision scar) ○ Exact etiology unknown, but can occur after any tissue injury (including surgical incisions) ○ 15x increased incidence in African Americans and other heavily pigmented people ○ Represent benign proliferation of type 1 and 3 collagen with excessive deposition of extracellular matrix (collagen, elastin, etc.) • Symptoms ○ Most patients asymptomatic, but can be painful, pruritic, or become superinfected (with ulceration) ○ Can become large and disfiguring • Imaging appearance: Nonspecific soft tissue density mass at site of incision ○ No clear distinguishing features from other entities on differential diagnosis • Multiple different treatment options available ○ Intralesional steroids and other injected medications ○ Surgical excision (with danger of repeat formation of keloids) ○ Laser or electron beam therapy

Injection Site Fluid or Gas Collection • Very common finding in subcutaneous tissues of anterior abdominal wall ○ Usually associated with injection of subcutaneous heparin, self-injection of insulin, etc. • Usually appear as small, low-density nodular foci associated with small ectopic gas, fluid, or blood products • May be misinterpreted as hematoma, abscess, or soft tissue infection but usually has little fluid and resolves quickly

Injection or Incision Site Hematoma or Seroma • Hematoma: Heterogeneous, high-attenuation (> 60 HU) mass in abdominal wall • Seroma: Lower density, more homogeneous collection of fluid without peripheral enhancement • May be misinterpreted as neoplasm (i.e., tumor implant at incision or laparoscopic port following surgical resection of malignancy), but imaging appearance is usually characteristic and should resolve over time

Injection or Incision Site Abscess • May be indistinguishable from uninfected hematoma or seroma ○ May require needle aspiration and fluid analysis in cases with high clinical suspicion • Suspicious imaging features for abscess include peripheral enhancement, worsening surrounding soft tissue edema and stranding (i.e., cellulitis), and internal foci of ectopic gas

Diabetic Lipodystrophy • Insulin-dependent diabetic patients may develop atrophy or hypertrophy of fat at insulin injection sites ○ Can be seen less commonly with several other drugs, including injected steroids (atrophy), octreotide (atrophy), and IGF-1 (hypertrophy) • Injection site lipoatrophy ○ Loss of fat at sites of repeated insulin injections ○ May be caused by allergic response to insulin, but now less common with use of human insulin • Injection site lipohypertrophy ○ Proliferation of fat and fibrous tissue at site of repeated injections – Common problem that is estimated to occur in almost 50% of insulin-dependent patients to some extent – Easier to palpate than to see visually or by imaging □ Forms palpable lump in subcutaneous tissues resembling miniature breast – Caused by repeated injections at 1 site without rotation to others □ Patients may prefer to do so as injections into sites of lipohypertrophy are less painful

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Calcified or Ossified Scar • Form of heterotopic ossification, which is also known as myositis ossificans traumatica ○ Relatively common sequela of abdominal surgery (25% in 1 series) ○ May be mild and self-limiting or more severe – May form hard, painful lesion that limits patient mobility • Abdominal incision may develop cartilaginous, osseous, or myelogenous (bone marrow) elements ○ Ossified scar may resemble rib, complete with cortex and medulla – Presumed to result from differentiation of multipotent mesenchymal cells into osteoblasts or chondroblasts ○ Particularly common in patients with renal failure or hypercalcemia ○ Usually located in subcutaneous tissues or musculofascial layer of abdominal wall – Often within linea alba following upper abdominal incision – Much more common in vertical incisions compared to horizontal incisions • Clinically evident as palpable hard mass and may raise concern for tumor within abdominal wall • Imaging appearance ○ Plain radiography: Ossified scar may be misinterpreted as retained foreign body or tumor

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Incision and Injection Sites ○ Most commonly seen in subcutaneous fat of buttocks, but very rarely seen in gluteal musculature itself (even though nurses have given "intramuscular" injections in buttocks for decades) – More common with injection of alkaline solutions Imaging appearance ○ Usually rounded (or linear) soft tissue or calcific density lesion ○ Appearance partially depends on phase of evolution and can resemble fat necrosis on CT with central fat density ○ Usually T1 hyperintense on MR with variable T2 signal depending on stage of evolution ○ Can be misinterpreted as a vascular, neoplastic, or inflammatory process within abdomen May be mistaken for other concerning entities on plain radiographs, including appendicolith, ureteral calculus, barium-lined diverticula, atherosclerotic calcification, etc. Not infrequently misinterpreted as sclerotic lesion in bones of pelvis on radiographs, but key is to note change in position relative to bone on other radiographs Easy diagnosis on CT due to subcutaneous location and characteristic appearance

○ Easily recognized on CT, with multiplanar reformations especially informative and demonstrating relationship of calcification to the incision line – Often appears linear, paralleling orientation of incision line

Endometrial Implantation in Abdominal Incision • Most often seen after cesarean section (80% of cases) or other uterine surgery ○ Abdominal wall endometriomas occasionally occur in patients without history of surgery, with exact method of dissemination in such cases unknown • Clinical symptoms ○ May first become clinically evident months to years after surgery ○ Classical symptoms include cyclical pain at incision site (usually suprapubic region with cesarean section) with menstruation ○ Very rarely may be incidental imaging finding in asymptomatic patient ○ Rare reports in literature of malignant transformation of abdominal wall endometriomas • Imaging ○ Abdominal wall endometrial implants do not resemble conventional endometriomas seen in pelvic cavity ○ Lesions appear solid and irregularly shaped/spiculated on CT or MR with moderate enhancement – Lesions typically hypointense on T1WI and hyperintense on T2WI (but can be T1 hyperintense like intrapelvic endometriomas) ○ Lesions appear solid, hypoechoic, and irregularly shaped on US with internal color Doppler flow (and discrete feeding vascular pedicle) • Characteristic imaging appearance with appropriate clinical history is virtually diagnostic, although lesions can be easily biopsied for confirmation • Lesions are typically surgically resected to alleviate symptoms

Tumor Implantation in Incision Sites • Can occur after open or laparoscopic incisions, although probably more common after laparoscopic surgery ○ Exact reason for higher risk of incision site metastasis with laparoscopy unclear, although almost certainly partially related to surgical technique – Some argue that CO₂ may spread tumor, although there is little supporting evidence • Imaging appearance is usually nonspecific, with soft tissue density mass in abdominal wall near or within incision site (either subcutaneous or musculofascial) ○ Usually resembles primary tumor (e.g., hypervascular mass for renal cell cancer implant) • Growth on sequential exams or FDG avidity is strongly suggestive, and abdominal wall lesions are typically easy to biopsy

Injection Granulomas • Usually sequelae of subcutaneous injection of drugs resulting in local fat necrosis with subsequent scarring and calcification

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DIFFERENTIAL DIAGNOSIS Desmoid • Locally aggressive mesenchymal neoplasms of connective or fibrous tissue that can be intraabdominal or extraabdominal (including abdominal wall) ○ When in abdominal wall, most often arise in rectus or oblique muscles (frequent incision sites) ○ 75% of patients with desmoids have had prior surgery (with Gardner syndrome representing another major risk factor) • Usually solid mass with well-defined margins that is hypoenhancing on CECT and classically low signal on all MR pulse sequences due to fibrous content

Abdominal Wall Neoplasms • Distinction between abdominal wall neoplasms (whether primary or metastatic) and postoperative change may not always be possible based on imaging appearance alone

Enterocutaneous Fistula • Enterocutaneous fistula in anterior abdominal wall may resemble fluid collection or abscess, especially if no clear tract from underlying bowel is visible • Distinction between incipient fistula and fluid collection may not be apparent clinically if cutaneous opening has not yet developed

DIAGNOSTIC CHECKLIST Consider • Always consider iatrogenic causes (incisions and injection sites) when confronted by subcutaneous and soft tissue masses

SELECTED REFERENCES 1. 2.

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Ecker AM et al: Abdominal wall endometriosis: 12 years of experience at a large academic institution. Am J Obstet Gynecol. 211(4):363.e1-5, 2014 Blanco M et al: Prevalence and risk factors of lipohypertrophy in insulininjecting patients with diabetes. Diabetes Metab. 39(5):445-53, 2013

Abdominal Incision and Injection Sites Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT in a young woman with history of cesarean section and cyclical anterior pelvic wall pain demonstrates a spiculated mass in the left anterior pelvic wall. (Right) Axial T1WI C+ MR in the same patient demonstrates the mass to be avidly enhancing. The location of the mass corresponded to the patient's cesarean section scar, and this was found to be an abdominal wall endometrioma at surgery.

(Left) Axial T1WI C+ MR in a young woman with cyclical abdominal wall pain at her cesarean section incision demonstrates an avidly enhancing mass , found to be an abdominal wall endometrioma. (Right) Sagittal T2WI MR in the same patient shows the lesion to be T2 hyperintense, and the lesion was hypointense on T1WI (not shown). Abdominal wall endometriomas often look different from conventional endometriomas, appearing T1 hypointense, T2 hyperintense, and moderately enhancing.

(Left) Axial CECT in a patient status post Whipple surgery for pancreatic cancer demonstrates an irregularly shaped hypodense mass arising within the abdominal wall incision, found to be recurrent tumor at surgery. (Right) Diabetic lipohypertrophy in an elderly man shows fibrofatty masses present bilaterally in the subcutaneous tissues of the periumbilical region. This patient had been injecting insulin into these same 2 sites for many months.

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Peritoneum, Mesentery, and Abdominal Wall

Peritoneal Inclusion Cyst KEY FACTS

• Loculated fluid trapped within peritoneal adhesions, typically surrounding ovary

IMAGING • Most often in pelvis (can rarely occur elsewhere) • Ultrasound ○ Loculated cystic mass with "spiderweb" pattern due to peritoneal adhesions reflecting from ovary ○ Fine septations throughout collection ○ Normal ovary at center or lateral margin of cyst ○ No solid mural or septal nodule to suggest malignancy ○ Usually anechoic fluid, but can have internal echoes due to hemorrhagic or proteinaceous contents • MR ○ Cystic mass with serous fluid (low signal on T1, high signal on T2) and thin internal septations ○ Margins of cyst outlined by other structures in pelvis (pelvic side walls, uterus, ovaries, loops of bowel)

(Left) Transvaginal US in a patient with history of multiple prior surgeries for Crohn disease shows an anechoic cyst with internal septations enveloping a normal-appearing ovary ,a classic appearance for peritoneal inclusion cyst. (Right) Axial CECT in a patient who had undergone colectomy with creation of a Hartmann pouch shows a loculated, thin-walled pelvic fluid collection partially surrounding the left ovary , characteristic features of a peritoneal inclusion cyst.

(Left) Longitudinal endovaginal US in a woman with 2-year history of pelvic pain and prior surgery for endometriosis demonstrates a complex fluid collection with internal septations surrounding the left ovary , which contains normal follicles. Surgery revealed a peritoneal inclusion cyst and normal ovary. (Right) Transvaginal US shows the right ovary enveloped by an anechoic fluid collection . A normal follicle is present within the ovary . This is a typical appearance of a peritoneal inclusion cyst.

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○ Morphologically normal ovary at center of cyst

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • •

Ovarian cancer Ovarian cyst or follicle Paraovarian cyst Hydrosalpinx

PATHOLOGY • Most often in women with prior pelvic surgery or inflammatory disorders (endometriosis, pelvic inflammatory disease, inflammatory bowel disease)

CLINICAL ISSUES • Primarily women of reproductive age • Can rarely occur in men or post-menopausal women

DIAGNOSTIC CHECKLIST • Cystic ovarian neoplasm or malignancy if thick septations, solid component/mural nodularity, or large ascites

Peritoneal Inclusion Cyst

Definitions • Loculated fluid trapped within peritoneal adhesions, typically surrounding ovary

IMAGING General Features • Best diagnostic clue ○ Loculated fluid collection surrounding ovary on endovaginal US with "spiderweb" pattern • Location ○ Primarily arise in pelvis ○ Rarely in other locations (usually intraperitoneal) • Size ○ 1-30 cm (large cysts can occupy entire pelvis)

Lymphocele • Prior history of lymph node dissection • Rounded cysts along pelvic side wall

PATHOLOGY General Features • Etiology ○ Most often found in women with history of prior pelvic surgery or inflammatory disorder of abdomen/pelvis – Most often after gynecologic surgery – Inflammatory causes include endometriosis, pelvic inflammatory disease, inflammatory bowel disease ○ Active ovarian function exudates fluid that then becomes trapped by adhesions

CLINICAL ISSUES

Imaging Recommendations

Presentation

• Best imaging tool ○ Ultrasound and MR

• Most common signs/symptoms ○ Pelvic pain, abdominal distension • Other signs/symptoms ○ Bowel or urinary symptoms due to mass effect ○ Can cause infertility ○ 10% are incidental findings on imaging or pelvic surgery ○ Laboratory markers: Cancer antigen 125 (CA-125) normal

Ultrasonographic Findings • Loculated cystic mass with "spiderweb" pattern due to peritoneal adhesions reflecting from ovary ○ Fine septations throughout collection – Rarely, low-resistance flow in vascularized septations ○ Normal ovary at center or lateral margin of inclusion cyst ○ No solid mural or septal nodule to suggest malignancy ○ Usually anechoic fluid, but can have internal echoes due to hemorrhagic or proteinaceous contents ○ Calcifications very uncommon ○ Only physiologic free fluid in pelvis (no frank ascites)

MR Findings • Cystic mass with serous fluid (low signal on T1, high signal on T2), thin internal septations, and discrete wall • Margins of cyst outlined by other structures in pelvis (pelvic side walls, uterus, ovaries, loops of bowel) • Normal ovary often at center of cyst

CT Findings • Loculated cyst in pelvis outlined by normal pelvic structures • Ovary may be seen within cyst

DIFFERENTIAL DIAGNOSIS Ovarian Cancer • Mural or septal nodularity, thick septations, low resistance vascularity within septations or solid components, ascites, and lymphadenopathy raise suspicion for malignancy • Normal ovary is not seen within cystic mass

Ovarian Cyst or Follicle • Cyst located within ovary adjacent to normal ovarian stroma or follicles

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Demographics • Age ○ 16-45 • Gender ○ Primarily women of reproductive age ○ Can rarely occur in post-menopausal women and men with extensive surgical history

Natural History & Prognosis • May be stable for many years • May decrease in size or resolve during menopause

Treatment • No treatment for asymptomatic cysts if cyst can be confidently distinguished from malignancy • Oral contraceptives can decrease cyst size by reducing ovarian fluid from ovulation • Cyst aspiration may provide short term symptom relief ○ Temporary solution, as fluid usually reaccumulates • Image-guided sclerotherapy may be an option • Surgery for symptomatic patients or if malignancy cannot be confidently excluded based on imaging and CA-125 ○ Cysts recur in 30-50% of patients undergoing surgery

DIAGNOSTIC CHECKLIST Consider • Cystic ovarian neoplasm or malignancy if thick septations, solid component/mural nodularity, or large ascites

Paraovarian Cyst • Cyst in broad ligament adjacent to ovary • Does not surround ovary like peritoneal inclusion cyst

Hydrosalpinx

SELECTED REFERENCES 1.

Veldhuis WB et al: Peritoneal inclusion cysts: clinical characteristics and imaging features. Eur Radiol. 23(4):1167-74, 2013

• Oblong, tubular cystic mass with "cog wheel" appearance • Ovary separate from dilated tube 131

Peritoneum, Mesentery, and Abdominal Wall

Lymphangioma (Mesenteric Cyst) KEY FACTS

• Congenital benign malformation of lymphatic system due to failure of embryologic lymphatic development • Generic descriptive term for benign congenital cystic mass arising in mesentery or omentum

IMAGING • Lymphangiomas of the abdomen are rare (7% of all lymphangiomas) ○ Can arise from or involve virtually any structure • Circumscribed cystic mass with variable density ○ Typically water density (near 0 HU) or chylous (< -20 HU), and only rarely hemorrhagic ○ No internal enhancement ○ Can be multiloculated (± septations) with "feathery" appearance ○ Soft lesions without mass effect: Easily indented by surrounding structures, such as mesenteric vessels/bowel

(Left) Axial CECT shows a complex cystic mass in the mesentery sandwiching a small bowel segment . The mass is near water density and has small foci of calcification in its septa and peripheral walls . The soft nature of the mass is indicated by the absence of bowel obstruction. (Right) Axial CECT shows a complex water-density mass in the mesentery, immediately adjacent to the pancreas and duodenum. The mass is divided by multiple septa , which, like the peripheral walls, are thin.

(Left) Axial CECT in a female patient shows a large, cystic mass with multiple septations filling much of the lower abdomen. Note the calcifications in the septa and the peripheral walls. (Right) Axial CECT in a female patient shows a cystic retroperitoneal mass with subtle septa and a small focus of calcification . The mass was resected and found to contain chylous fluid (typical of a lymphangioma) and an epithelial lining, features that help account for the variety of names for this tumor.

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○ Usually hypointense on T1WI MR and hyperintense on T2WI

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • • •

Loculated ascites Gastrointestinal duplication cyst Pancreatic pseudocyst Peritoneal inclusion cyst Cyst or cystic tumor arising from visceral organ

CLINICAL ISSUES • Symptoms are rare (particularly in adults) ○ Rare symptoms due to mass effect, superinfection, or internal hemorrhage • Surgery is treatment of choice when necessary

DIAGNOSTIC CHECKLIST • Differentiate from other primary cystic lesions or tumors of visceral organs

Lymphangioma (Mesenteric Cyst)

Synonyms • Lymphoepithelial cyst, cystic lymphangioma, mesenteric cyst, lymphatic malformation

Definitions • Congenital benign malformation of lymphatic system arising due to failure of embryologic lymphatic development • Generic descriptive term for benign congenital cystic mass arising in mesentery or omentum

IMAGING General Features • Best diagnostic clue ○ Cystic mass (without mass effect) in mesentery or retroperitoneum • Location ○ Majority of lymphangiomas arise in head, neck, or axillae ○ Lymphangiomas of abdomen rare (7% of all lymphangiomas) – Can involve multiple compartments of peritoneum or retroperitoneum – Can arise from or involve virtually any structure ○ Lymphangiomatosis: Widespread lymphangiomas (usually liver, spleen, mediastinum, lungs, mesentery) – Usually presents in infants and young children • Size ○ Few mm to 40 cm in diameter

CT Findings • Circumscribed cystic mass with variable density ○ Typically water density (near 0 HU) or chylous (< -20 HU), with lesions rarely demonstrating hemorrhagic contents ○ No internal enhancement • Can be multiloculated (± septations) with "feathery" appearance ○ ± fine calcifications along cyst wall • Soft lesions without mass effect that are indented by surrounding structures (e.g., mesenteric vessels or bowel)

Ultrasonographic Findings • Fluid-filled cystic structure with thin internal septa ○ ± internal echoes due to debris, hemorrhage, or infection

MR Findings • Multiloculated cyst, usually hypointense on T1WI and hyperintense on T2WI ○ Can be T1 hyperintense due to internal fat/chyle

DIFFERENTIAL DIAGNOSIS Loculated Ascites • May appear similar to lymphangioma, but there is typically a known underlying cause for ascites (e.g., cirrhosis)

Gastrointestinal Duplication Cyst • Cystic mass with thick wall abutting bowel

Cyst or Cystic Tumor Arising From Visceral Organ • Mesenteric cysts can abut visceral organs (such as pancreas or kidneys) and mimic cystic lesion arising from organ (e.g., exophytic renal cyst)

Peritoneal Inclusion Cyst • Cystic mass in reproductive-age female after surgery • Loculated cystic lesion conforming to shape of pelvis and often surrounding ovary

PATHOLOGY General Features • Etiology ○ Failure of normal embryologic development with lymphatic tissue not communicating with rest of lymphatic system

Gross Pathologic & Surgical Features

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

• Thin walled and multiseptated with serous, serosanguineous, or chylous fluid contents

Microscopic Features • Cuboidal or columnar cells lining cyst ± smooth muscle, lymphatics, and blood vessels within walls

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Usually asymptomatic (particularly in adults) ○ Rare symptoms (abdominal distention, pain) due to size (particularly in neonates) or superinfection ○ Theoretical risk of pseudomyxoma peritonei

Demographics • Epidemiology ○ Can occur at any age, but 75% discovered age < 5 years – 90% continue to grow until 2 years of age ○ M>F ○ Rare (1/40,000 persons)

Treatment • Follow asymptomatic patients with repeat imaging • Aspiration and sclerosing agents are usually ineffective • Open or laparoscopic surgical resection if lesion is symptomatic or cannot be differentiated from malignancy ○ Good prognosis after surgery: 0-13.6% recurrence rate

DIAGNOSTIC CHECKLIST Consider • Differentiate from other primary cystic lesions or tumors of visceral organs ○ Look for claw sign of cystic mass arising from visceral organ

SELECTED REFERENCES 1.

Kwag E et al: CT features of generalized lymphangiomatosis in adult patients. Clin Imaging. 37(4):723-7, 2013

Pancreatic Pseudocyst • Cyst with visible wall in patient with history of pancreatitis 133

Peritoneum, Mesentery, and Abdominal Wall

Lymphangioma (Mesenteric Cyst)

(Left) Axial CECT demonstrates innumerable low density, cystic masses throughout the retroperitoneum. The lesions surround major vasculature without mass effect or narrowing. (Right) Axial CECT more caudal in the same patient demonstrates similarappearing cystic lesions along the iliac chains in the pelvis. Patients with lymphangiomatosis, as in this case, can have innumerable lymphangiomas anywhere in the body.

(Left) T2WI MR demonstrates a lymphangioma in the left pelvic retroperitoneum. As in this case, most lymphangiomas are uniformly T2 hyperintense, although intralesional hemorrhage, debris, or fat can result in a more intermediate T2 signal. (Right) Axial T1 C+ MR in the same patient demonstrates an absence of internal enhancement or nodularity within the cystic lesion , features that would cast doubt on the diagnosis of a lymphangioma.

(Left) Axial CECT demonstrates a cystic mass in the retroperitoneum. Notice the lack of any internal enhancing soft tissue or mural nodularity. (Right) Coronal VR CECT better illustrates how the mass envelops vasculature without appreciable mass effect or narrowing (characteristic of lymphangiomas).

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Lymphangioma (Mesenteric Cyst) Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT demonstrates a cystic mass in the left retroperitoneum. The lesion abuts the pancreatic tail and left colon without appreciable mass effect. (Right) Axial CECT in the same patient nicely demonstrates the multiloculated, "feathery" morphology of the lesion . This appearance is quite common with lymphangiomas, which frequently appear to have multiple internal discrete components or locules.

(Left) Coronal volumerendered CECT demonstrates a multiloculated cystic lesion in the left retroperitoneum. The lesion envelops multiple arteries and veins , which do not appear deviated or narrowed. (Right) Coronal VR CECT again nicely demonstrates the morphology of the lymphangioma , which has several discrete cystic components and appears multiloculated. These lesions are characteristically soft, and while they abut adjacent structures, there is typically no mass effect.

(Left) Axial CECT shows a thinwalled mass with water density, indented by a mesenteric vessel in this patient with cystic lymphangioma. (Right) Axial CECT shows another view of the water-density, thin-walled mass being indented by a mesenteric vessel .

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Peritoneum, Mesentery, and Abdominal Wall

Desmoid KEY FACTS

• Rare, benign, locally aggressive, nonencapsulated mesenchymal neoplasms of connective or fibrous tissue

IMAGING • Can be intraabdominal or extraabdominal (including abdominal wall) ○ When involving abdominal wall, often involve rectus or oblique muscles, frequently at incision sites ○ When involving mesentery, may retract or compress adjacent bowel loops ± small bowel obstruction • Usually solid with well-defined margins (but can be infiltrative in appearance) • CT: Hyperdense to muscle on NECT and usually hypoenhancing on CECT (but rarely avidly enhancing) • MR: Classically thought to be low signal on all MR pulse sequences due to fibrous content but this is unreliable ○ Usually heterogeneously high signal on T2WI and STIR ○ Usually homogeneously isointense/hypointense on T1WI

(Left) Axial CECT in a 43-yearold man with Gardner syndrome shows a huge mesenteric mass that encases and partially obstructs the small bowel. A portion of the mass has central cavitation and an air-fluid level that might be misinterpreted as aneurysmal dilation of the bowel lumen. (Right) Gross pathology of the resected mass from the same case shows encasement of the small bowel. A portion of the mass is necrotic and communicates with the bowel lumen, accounting for the airfluid level on CT.

(Left) Axial CECT demonstrates a relatively homogeneous, enhancing, well-circumscribed mass in the right anterior pelvis. (Right) Axial CECT in the same patient demonstrates a very similar-appearing smaller mass in the more inferior pelvis. This was a patient with Gardner syndrome, and both of these lesions were found to represent desmoid tumors.

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○ Bands of internal low signal on all pulse sequences

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • •

Soft tissue sarcoma Leukemia and lymphoma Carcinoid tumor Primary small bowel tumors extending into mesentery

PATHOLOGY • Strong associations with Gardner syndrome and familial adenomatous polyposis (FAP) • Other major risk factors include previous abdominal surgery (75% of cases), trauma, or oral contraceptives

CLINICAL ISSUES • Complications arise from locally aggressive growth pattern with compression and invasion of adjacent structures • Surgical resection difficult in many cases as result of involvement of adjacent critical structures • Recurrence after surgery is very common

Desmoid

Synonyms • Deep or aggressive fibromatosis

Definitions • Rare, benign, locally aggressive, nonencapsulated mesenchymal neoplasms of connective or fibrous tissue

IMAGING General Features • Best diagnostic clue ○ Small bowel mesentery or abdominal wall mass arising at site of scarring from prior surgery • Location ○ Can be intraabdominal or extraabdominal (including abdominal wall) – Abdominal desmoids □ Account for 2/3 of all desmoid tumors □ Tumors associated with Gardner syndrome or familial adenomatous polyposis (FAP), usually intraabdominal □ Most commonly occur in small bowel mesentery, but can occur nearly anywhere – Extraabdominal □ Pregnancy-related desmoid tumors tend to occur within abdominal wall □ 1/3 occur in shoulder and upper extremity □ ~ 20% in chest wall, ~ 10% in head and neck □ Musculature most often involved: Rectus, internal/external oblique, psoas, pelvic (rare) • Morphology ○ Clear, lobulated margin (75%) ○ Ill defined, infiltrative (25%) • Key concepts ○ Locally aggressive primary mesenchymal tumor – Sometimes classified as low-grade fibrosarcoma or subgroup of fibromatosis – Tend to arise in musculoaponeurotic planes – Tend to invade locally, recur after treatment, and grow very rapidly, especially in Gardner syndrome – May involve bowel loops, bladder, ribs, pelvic bones, and virtually any other structure ○ Desmoids can be solitary or multiple (15% of cases) ○ Etiology – Most cases are sporadic – 75% of patients with desmoid tumors have had prior abdominal surgery – May be associated with Gardner syndrome and FAP □ Familial polyposis coli, osteomas, dental defects, congenital pigmented lesions of retina □ Epidermoid (sebaceous) cyst and fibromas of skin □ Periampullary, adrenal, thyroid, and liver carcinomas

CT Findings • Abdominal wall desmoids ○ Usually solid with well-defined margins (but can be infiltrative in appearance)

○ Homogeneous or heterogeneous density on NECT (hyperdense compared to surrounding muscle) ○ Usually hypoenhancing on CECT (but rarely avidly enhancing) ○ Often involve rectus or oblique muscles, frequently at incision sites • Mesenteric desmoids ○ Soft tissue mass with well-defined or ill-defined margins ○ Hyperdense relative to muscle on NECT with variable, heterogenous enhancement on CECT ○ Whorled appearance: Radiating fibrotic strands into adjacent mesenteric fat ○ May displace, retract, or compress adjacent bowel loops ± small bowel obstruction ○ ± infiltration into adjacent organs and musculature ○ Calcification uncommon

MR Findings

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

• Can be poorly marginated or very well circumscribed ○ Often will cross fascial boundaries (1/3 of cases) and may be lobulated or infiltrative • Classically thought to be low signal on all pulse sequences due to fibrous content ○ Not a consistent or common feature, and may be seen with other entities (including malignancies such as fibrosarcoma and malignant fibrous histiocytoma) ○ Usually homogeneously isointense or mildly hypointense on T1WI ○ Heterogeneously high signal on T2WI and STIR – Higher T2 signal more common with actively growing or aggressive desmoids ○ Bands of low signal on all pulse sequences (likely corresponding to bands of fibrosis and collagen) seen in 2/3 of cases ○ Variable enhancement on post-gadolinium sequences; usually heterogeneous

Ultrasonographic Findings • Well-defined mesenteric mass with variable echogenicity

Radiographic Findings • Fluoroscopic double-contrast studies ○ Familial adenomatous polyposis: Innumerable, variably sized radiolucent filling defects in colon

DIFFERENTIAL DIAGNOSIS Soft Tissue Sarcoma • Imaging cannot differentiate desmoid tumor in abdominal wall or musculature from sarcoma; biopsy required • History of prior surgical incision at site of mass suggests desmoid rather than malignancy

Leukemia and Lymphoma • Discrete or confluent retroperitoneal and mesenteric lymphadenopathy • Much softer than desmoid (envelops, but rarely obstructs, bowel or vessels)

Omental or Mesenteric Metastases • Usually multiple, less well-defined lesions; often associated with stranding/induration in mesentery/omentum 137

Peritoneum, Mesentery, and Abdominal Wall

Desmoid

Carcinoid Tumor • Usually occurs in right lower quadrant (ileal) mesentery • Desmoplastic reaction and calcification very common (not found in desmoids)

Small Bowel Tumors Extending Into Mesentery • GI stromal tumors (GIST) or small bowel adenocarcinoma can extend into mesentery and appear similar to desmoid tumor

Sclerosing Mesenteritis • Usually less mass-like than desmoid • Retractile mesenteritis can produce discrete mesenteric mass with desmoplastic reaction and calcification

PATHOLOGY General Features • Etiology ○ Exact cause is unknown ○ Majority of cases are sporadic ○ Strong associations with Gardner syndrome and FAP – Due to mutation in APC gene (5q22) – Autosomal dominant disorder characterized by innumerable colonic polyps and multiple extracolonic tumors (including desmoids in 18-20% of cases) ○ Other major risk factors include previous abdominal surgery (75% of cases), trauma, or oral contraceptives ○ Most often in women of childbearing age

Gross Pathologic & Surgical Features • Desmoid tumors may be intermediate step between reparative process and true malignancy • Tan/white, firm, well- or poorly defined mass • May be "rock hard" and resistant to percutaneous biopsy

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Patients may be asymptomatic or may present with abdominal pain and palpable mass ○ Acute abdominal findings – Due to ischemia/ulceration of mass – Encasement of mesentery and bowel ischemia and obstruction progressive resection of bowel short gut syndrome – Hydronephrosis due to ureteral encasement

Demographics • Age ○ 70% of cases between 20-40 years old ○ Tends to be more aggressive in younger patients • Gender ○ M:F = 1:3 ○ Increased incidence in women of childbearing age • Epidemiology ○ Rare: 2-4 cases per million per year ○ 18-20% of patients with Gardner syndrome develop desmoid tumor

Natural History & Prognosis • Complications 138

○ Locally aggressive growth pattern with compression and invasion of adjacent structures – Intraabdominal desmoids tend to be most aggressive and infiltrative (particularly when associated with FAP or Gardner syndrome) – Can cause bowel obstruction, ureteral obstruction, chronic bowel ischemia due to encasement and narrowing of vasculature – In pelvis, can involve bladder and cause bladder outlet obstruction, involve fallopian tubes and cause hydrosalpinx – Extraabdominal desmoids can involve nerves and cause pain; chest wall desmoids can invade pleura ○ Short gut syndrome after multiple small bowel resections ○ High recurrence rate (up to 2/3 of cases) – Imaging and pathology not predictive of recurrence • Poor prognostic features ○ Large size of tumor ( > 10 cm) and multiplicity ○ Extensive involvement of bowel loops, encasement of mesenteric vessels, and ureters

Treatment • Stable, asymptomatic desmoids: Follow with serial imaging • Symptomatic desmoids should be surgically resected whenever possible ○ May be difficult due to involvement of adjacent critical structures – Surgery for sporadic cases often curative but morbidity significant – Particularly when small bowel mesentery involved, surgical resection can result in significant morbidity (bowel ischemia, short gut syndrome, obstruction, fistula, etc.) ○ Recurrence after surgery is very common, particularly with extraabdominal desmoids • Conservative management recommended for symptomatic desmoids which are unresectable ○ Radiation therapy: More successful in abdominal wall rather than mesentery ○ Systemic therapy: cytotoxic agents (including anthracyclines), antiestrogen agents (e.g., tamoxifen), interferon, molecular-targeted agents (e.g. imatinib), steroids, NSAIDs (e.g., sulindac)

DIAGNOSTIC CHECKLIST Consider • Consider desmoid tumors in patients with history of prior abdominal surgery • Look for other features of Gardner syndrome • Rule out other more common causes of a solid mesenteric mass

SELECTED REFERENCES 1. 2.

Lamboley JL et al: Desmoid tumour of the chest wall. Diagn Interv Imaging. 93(7-8):635-8, 2012 Shinagare AB et al: A to Z of desmoid tumors. AJR Am J Roentgenol. 197(6):W1008-14, 2011

Desmoid Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT demonstrates an infiltrative, hypoenhancing mass in the right anterior abdominal wall musculature at the site of a prior surgical incision. (Right) Axial T1WI C+ FS MR in the same patient demonstrates relatively avid enhancement of the mass , which is once again noted to be quite infiltrative and poorly marginated. In cases like this, only histologic confirmation can differentiate a desmoid from a soft tissue malignancy.

(Left) Axial CECT in a patient with Gardner syndrome shows a small soft tissue density mesenteric mass , a typical desmoid in this setting. This caused no symptoms and was not resected. (Right) Axial CECT in the same patient 8 months later shows the mesenteric desmoid to have dramatically grown and now encases mesenteric vessels and the bowel. The patient was treated with complete resection of the small bowel and mesentery followed by small bowel transplantation.

(Left) Axial CECT in a young woman with Gardner syndrome 2 years after total colectomy shows mesenteric fibromatosis (desmoids) encasing the entire small bowel mesentery, filling the abdominal cavity. (Right) Axial CECT demonstrates a very homogeneous, hypoenhancing mass in the pelvis encasing loops of adjacent bowel. This was found to be a desmoid tumor. Desmoids with extensive involvement of the bowel can be very difficult to surgically resect.

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Mesothelioma KEY FACTS

TERMINOLOGY

• Typically no distant metastatic disease or lymphadenopathy

• Primary malignant neoplasm arising from peritoneum

TOP DIFFERENTIAL DIAGNOSES

IMAGING

• • • • •

• Malignant mesothelioma can arise from any serosal membrane (pleura, peritoneum, pericardium, tunica vaginalis) ○ 20-30% of malignant mesotheliomas arise in peritoneum • CT: Omental and peritoneal stranding, nodularity, and discrete masses ○ Stellate, thickened (pleated) mesentery secondary to encasement and straightening of mesenteric vessels ○ Tumor spreads along serosal surfaces and can directly invade adjacent viscera, especially colon and liver ○ Can spread across diaphragm into pleural cavity ○ Less ascites than peritoneal carcinomatosis ○ Calcified pleural plaques may be clue to diagnosis • MR: Low to intermediate T1WI and intermediate to high T2WI signal intensity of omental and peritoneal masses

(Left) Axial CECT in an elderly man with abdominal distention shows a calcified pleural asbestos plaque . The parietal peritoneum under the diaphragm is diffusely thickened with a discrete mass . (Right) Axial CECT in the same patient shows an omental mass with loculated ascites. The abdominal findings are indistinguishable from peritoneal carcinomatosis, but the asbestos plaque is an important clue to the diagnosis of mesothelioma.

(Left) Axial CECT in an elderly man with abdominal pain shows marked mass-like omental thickening and encasement of bowel loops . Open biopsy confirmed malignant mesothelioma. (Right) Axial NECT in a patient with renal insufficiency shows a lobulated mass in the omentum abutting the anterior abdominal wall. Surgical biopsy confirmed malignant mesothelioma. Such an isolated mass is an unusual manifestation of the disease, which is usually widespread at the time of diagnosis.

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Peritoneal carcinomatosis Lymphomatosis Pseudomyxoma peritonei Tuberculous peritonitis Sclerosing mesenteritis

PATHOLOGY • Relationship with asbestos exposure is less strong than with pleural mesothelioma (requires much higher exposure to asbestos than pleural mesothelioma)

CLINICAL ISSUES • Rare tumor (1-2 cases per million) with extremely poor prognosis (most patients die within 1 year) • M:F > 4:1; usually 6th-7th decade • Treatment: Cytoreductive surgery and peritonectomy combined with heated intraperitoneal chemotherapy

Abdominal Mesothelioma

• Malignant mesothelioma, peritoneal mesothelioma

MR Findings

Definitions

• Low to intermediate T1WI signal intensity of peritoneal masses • Intermediate to high T2WI signal of peritoneal masses ○ Fluid-fluid levels secondary to hemorrhage • Nodules and peritoneal thickening are relatively hypoenhancing on T1WI C+ images

• Primary malignant neoplasm arising from peritoneum

IMAGING General Features • Best diagnostic clue ○ Peritoneal masses or omental caking associated with calcified pleural plaques • Location ○ Malignant mesothelioma can arise from pleura, peritoneum, pericardium, tunica vaginalis, or any other serosal membrane in body – 70% of malignant mesotheliomas arise in pleura – 20-30% arise in peritoneum – Very few cases involve both pleura and peritoneum • Size ○ Usually involves peritoneal surfaces diffusely or multifocally ○ Focal masses range from few mm to many cm

Ultrasonographic Findings • Hypoechoic, sheet-like peritoneal and omental masses • Echogenic areas within hypoechoic masses may represent entrapped mesenteric or omental fat

Nuclear Medicine Findings • Tumor tends to be FDG-avid, although little data regarding use of PET/CT in diagnosis, staging, or surveillance

Imaging Recommendations • Best imaging tool ○ Contrast-enhanced CT

DIFFERENTIAL DIAGNOSIS

Radiographic Findings

Peritoneal Carcinomatosis

• Radiography ○ Calcified pleural plaques in 50% of patients with peritoneal mesotheliomas – Only 20% of pleural mesotheliomas have calcified plaques – Suggests heavier asbestos exposure in patients with peritoneal mesothelioma

• Most common cause of omental caking and peritoneal implants • Usually metastatic adenocarcinoma, especially ovarian and other gynecological cancers, stomach, colon, and pancreatic cancers • Cannot be distinguished from mesothelioma by imaging ○ Often associated with liver metastases and lymphadenopathy unlike mesothelioma ○ Usually greater degree of ascites than mesothelioma for a given solid tumor burden

CT Findings • Omental and peritoneal stranding, nodularity, and discrete masses ○ Stellate, thickened (pleated) mesentery secondary to encasement and straightening of mesenteric vessels ○ Spreads along serosal surfaces and can directly invade adjacent viscera, especially colon and liver ○ Can spread across diaphragm into pleural cavity ○ Calcification in peritoneal masses is very uncommon • 2 primary forms ○ Diffuse (desmoplastic) peritoneal mesothelioma: Diffuse thickening of peritoneal surfaces and omentum with involvement of entire abdomen and multiple discrete masses – Aggressive form that accounts for majority of cases ○ Localized (focal) peritoneal mesothelioma: Solid dominant mass in 1 portion of abdomen without widespread disease or nodularity – Mass may infiltrate and involve adjacent local organs, but does not spread to distant sites in abdomen – Lesser degree of ascites – May have better prognosis, but only represents a minority of cases • Variable amount of ascites: Massive ascites uncommon ○ Amount of ascites in mesothelioma (for a given amount of solid tumor burden) tends to be less than is seen with peritoneal carcinomatosis

Peritoneum, Mesentery, and Abdominal Wall

Synonyms

• Calcified pleural plaques may be clue to diagnosis • Does not typically demonstrate distant metastatic disease or lymphadenopathy

TERMINOLOGY

Lymphomatosis • Usually associated with Burkitt lymphoma, high-grade lymphomas, and AIDS-related lymphoma • May be virtually identical in appearance to carcinomatosis or mesothelioma • Omental and peritoneal nodules, masses, and caking • Usually concomitant lymphadenopathy in most cases

Pseudomyxoma Peritonei • Disseminated low-density mucinous implants which "scallop" margins of visceral serosal surfaces, especially liver and spleen ○ Lower in density than solid implants from mesothelioma and carcinomatosis ○ Curvilinear calcifications common in implants • Most result from appendiceal tumors, but can arise from any mucinous neoplasm including ovary

Tuberculous Peritonitis • Smooth peritoneal thickening with pronounced enhancement (discrete masses less common) • High-attenuation ascites (25-45 HU) that is often loculated • Often associated with low-attenuation lymphadenopathy

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Peritoneum, Mesentery, and Abdominal Wall

Abdominal Mesothelioma

Sclerosing Mesenteritis

Demographics

• Increased attenuation and infiltration of mesentery with small prominent mesenteric nodes • Can present with solitary discrete calcified mass in endstage form

• Age ○ Usually 6th-7th decade but can occur at any age ○ Slightly lower mean age compared to pleural mesothelioma • Gender ○ M:F > 4:1 ○ Higher incidence in women compared to pleural mesothelioma • Epidemiology ○ Rare: 1-2 cases per million ○ 200-400 cases diagnosed annually in USA (vs. 2,0003,000 cases of all types/locations) ○ Disease clusters around shipyards, docks, asbestos mines, and factories ○ Nonoccupational exposure to asbestos and zeolites common in Turkey

Peritoneal Inclusion Cyst • Walled-off collection of fluid lined by peritoneum • Occurs almost exclusively in women of reproductive age who have had prior abdominal surgery • Sometimes (incorrectly) called benign cystic or multicystic mesothelioma ○ Unfortunate and potentially confusing misnomer, whose use should be discouraged ○ Has nothing in common with malignant mesothelioma

PATHOLOGY General Features • Etiology ○ Relationship with asbestos exposure is less strong than with pleural mesothelioma – Likely requires much higher exposure to asbestos than pleural mesothelioma – Asbestos may be inhaled or ingested, and likely increases risk for malignancy through chronic irritation of pleura or peritoneum – 20-40 year latency between exposure and diagnosis ○ Other major risk factors include radiation and other carcinogens (especially metal fibers) ○ Questionable link with simian virus 40 as cocarcinogen • Associated abnormalities ○ Asbestos-related pleural and parenchymal lung disease ○ Multifocal origin from mesothelial lining of abdomen and pelvis ○ 3 histologic types – Epithelial (54%) – Sarcomatoid (21%) – Biphasic (mixed epithelial-sarcomatoid) (25%)

• Extremely poor prognosis ○ Median survival = 6 months; death usually within 1 year ○ Probably slightly worse prognosis than pleural mesothelioma • Solitary tumors have better prognosis than diffuse intraabdominal disease • Remains confined to abdominal cavity and invades locally ○ Does not disseminate hematogenously to brain, bone, or lung

Treatment • Options, risks, complications ○ Cytoreductive surgery and peritonectomy combined with heated intraoperative intraperitoneal chemotherapy ○ Systemic chemotherapy in patients who are not candidates for cytoreduction or intraperitoneal chemotherapy

DIAGNOSTIC CHECKLIST

Gross Pathologic & Surgical Features

Consider

• Solid tumor masses growing along peritoneal surfaces • Encasement and invasion of adjacent viscera • Recurs along surgical and laparoscopy tracts

• Consider in patients with diffuse peritoneal tumor on CT and stigmata of asbestos exposure • Peritoneal carcinomatosis is much more common than mesothelioma

Microscopic Features • Variable histologic appearance of tumor cells ○ Open biopsy rather than FNA often needed for diagnosis • Positive immunostaining for calretinin, keratin, vimentin, and thrombomodulin

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pain-predominant type: Patients present with abdominal pain and dominant tumor mass with little ascites ○ Ascites-predominant type: Patients present with abdominal distention as a result of ascites and widespread disease (usually without dominant mass) ○ Other signs/symptoms – Weight loss, malaise, cramping, new onset hernia 142

Natural History & Prognosis

Image Interpretation Pearls • Presence of distant metastases outside abdominal cavity makes malignant mesothelioma unlikely

SELECTED REFERENCES 1.

Diop AD et al: CT imaging of peritoneal carcinomatosis and its mimics. Diagn Interv Imaging. ePub, 2014

Abdominal Mesothelioma Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT shows subtle infiltration of the omental fat and ascites , findings that may be seen in infectious, inflammatory, or malignant disease. (Right) Axial CECT in the same patient shows a more discrete tumor mass in the pelvis. At surgery, tumor was found along the entire surface of the peritoneal lining and omentum, and mesothelioma was confirmed.

(Left) Axial CECT shows an infiltrative, discrete omental mass . No other primary malignancy was evident. At laparotomy, there was extensive tumor throughout the omentum and mesentery, diagnosed as primary peritoneal mesothelioma. (Right) Axial CECT of recurrent mesothelioma shows distention of the abdomen due to bowel dilation (partial obstruction) and extensive tumor. The tumor is somewhat difficult to recognize, as it surrounds the bowel and infiltrates the mesentery.

(Left) Axial CECT demonstrates extensive tumor surrounding the liver and invading the abdominal wall. Other tumor implants are found elsewhere in the omentum. Notice the relative lack of ascites despite the large amount of tumor. This was found to represent peritoneal mesothelioma. (Right) Coronal NECT in the same patient demonstrates discrete, pleural-based masses in the right hemithorax, also found to represent mesothelioma. Pleural and peritoneal mesothelioma in the same patient is quite rare.

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Peritoneum, Mesentery, and Abdominal Wall

Peritoneal Metastases KEY FACTS

• Metastatic disease to omentum, peritoneal surface, peritoneal ligaments, or mesentery

IMAGING • CT: Poor sensitivity for implants < 1 cm (7-50%) ○ Micronodular pattern: Earliest findings may be subtle peritoneal thickening and hyperenhancement – Stranding and nodularity in mesentery may result in "pleated" or "stellate" appearance ○ Nodular pattern: More discrete nodules may be present measuring > 5 mm in size ○ Omental caking: Discrete omental masses coalesce into larger conglomerate omental masses ○ Thickening and nodularity along surface of bowel may reflect tumor implants on serosal surface ○ Ascites (often loculated) may be present • MR: Sensitivity of MR is comparable to, or greater than, CT for implants > 1 cm, but limited for small implants

(Left) Axial anatomic rendering of peritoneal metastases. Note the anterior omental cake and serosal implants . (Right) Axial CECT demonstrates extensive omental caking in the anterior pelvic omentum, compatible with carcinomatosis. Notice the presence of ascites , which is commonly associated with carcinomatosis.

(Left) Axial T1 C+ FS MR in the same patient demonstrates enhancing soft tissue in the omentum. Although debatable, some sources suggest that MR may have slightly increased sensitivity for carcinomatosis compared to CT. (Right) Axial PET/CT image in the same patient demonstrates that the omental caking shows avid FDG uptake. No primary tumor was discovered in this case, and this was found to be peritoneal serous papillary carcinoma.

144

○ Diffusion-weighted imaging (DWI) may sensitivity ○ Tumor implants typically T1WI hypointense, intermediate signal on T2WI, and variable enhancement on T1WI C+ images depending on type of tumor

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • • •

Tuberculous peritonitis Abdominal mesothelioma Peritoneal lymphomatosis Primary peritoneal serous papillary carcinoma Pseudomyxoma peritonei

PATHOLOGY • Usually due to peritoneal spread of surface epithelium tumors, although hematogenous spread also possible • Most common: Ovarian and GI adenocarcinomas (gastric, colorectal, pancreas, appendix, gallbladder)

CLINICAL ISSUES • Common complications: Bowel and ureteral obstruction

Peritoneal Metastases

Synonyms • Peritoneal carcinomatosis, peritoneal implants, omental caking

Definitions • Metastatic disease to omentum, peritoneal surface, peritoneal ligaments, or mesentery

IMAGING General Features • Best diagnostic clue ○ Peritoneal stranding, nodularity, omental caking, or complex ascites in a patient with a known history of malignancy • Location ○ Peritoneum, mesentery, peritoneal ligaments • Size ○ Variable, ranging from tiny micronodules (< 5 mm) to large, confluent omental caking

CT Findings • CT has limited sensitivity for peritoneal metastases (2590%), particularly implants measuring < 1 cm (7-50%) ○ Particularly difficult to identify tumor implants in certain anatomic locations (liver hilum, bladder dome, subdiaphragmatic positions, mesenteric root, lesser omentum, serosal surface of small bowel) ○ Utilizing positive oral contrast media may be helpful in better differentiating tumor implants from adjacent bowel loops • 3 primary patterns of carcinomatosis on imaging ○ Micronodular pattern – Earliest findings may be subtle peritoneal thickening and hyperenhancement ± nodularity – Omentum often easiest site to appreciate carcinomatosis with nodularity, stranding, and infiltration □ Other common sites include paracolic gutters, along surface of liver, along undersurface of diaphragms, and pelvic cul-de-sac – Stranding and nodularity in mesentery may result in a "pleated" or "stellate" appearance ○ Nodular pattern – More discrete peritoneal nodules measuring > 5 mm in size ○ Omental caking – Omental nodules coalesce into larger conglomerate omental masses • Thickening and nodularity along surface of bowel may reflect tumor implants along serosal surface of bowel ○ Thickened bowel loops may appear encapsulated as result of extensive serosal metastases • Tumor implant density will vary based on histology of primary malignancy, with most hypovascular tumors appearing as solid, hypodense soft tissue nodules ○ Mucinous tumors may appear as low density or cystic tumor implants

○ Hypervascular tumors such as renal cell carcinoma may have hyperenhancing peritoneal metastases, which are more conspicuous on arterial phase imaging ○ Calcifications may be associated with certain mucinous neoplasms • Ascites usually present with loculated ascites common in cases with advanced peritoneal carcinomatosis • Tumor implants may cause bowel obstruction with thickening and nodularity at site of transition from dilated to nondilated bowel

MR Findings • Sensitivity of MR is comparable to, and perhaps even greater than, CT for implants > 1 cm ○ Fat suppression increases conspicuity of tumor implants in omentum and mesentery ○ Diffusion-weighted imaging (DWI) offers increased sensitivity for tumor implants, which demonstrate restricted diffusion ○ Sensitivity of MR, even with inclusion of DWI, is still limited for small implants < 1 cm in size • Caution needed when interpreting SSFSE/HASTE images, as bulk motion of fluid within ascites can lead to signal voids that might be confused for tumor implants • Tumor implants typically are hypointense on T1WI, intermediate to high signal on T2WI, and demonstrate variable enhancement on T1WI C+ images depending on type of tumor ○ Peritoneal thickening and hyperenhancement often present on T1WI C+ images • T2 hyperintense ascites fluid often present ± internal complexity (e.g., septations) and loculation

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Not sensitive for detection of peritoneal implants, particularly in absence of ascites ○ Complex ascites with septations and hypoechoic tumor implants/omental caking

Nuclear Medicine Findings • PET/CT ○ Offers greater sensitivity relative to PET, CT, or MR in isolation (> 90%) – May detect occult metastases which were difficult to appreciate on CT or MR due to anatomic location – Still limited in its sensitivity for lesions < 1 cm in size – Certain tumors which commonly metastasize to peritoneum may not be highly FDG avid (mucinous neoplasms and signet ring gastric cancers) – Mistaking focal physiologic uptake in bowel or ureters for tumor implant is common pitfall ○ Carcinomatosis may present as focal uptake in discrete masses or diffuse peritoneal uptake (with radiotracer uptake highlighting contours of peritoneal lining)

Fluoroscopic Findings • Mural extrinsic filling defects secondary to serosal implants on surface of small bowel ± findings of small bowel obstruction • Spiculated extrinsic impression secondary to tethering of rectosigmoid from intraperitoneal mets to pouch of Douglas 145

Peritoneum, Mesentery, and Abdominal Wall

Peritoneal Metastases

Imaging Recommendations • Best imaging tool ○ CECT or MR • Protocol advice ○ Positive oral contrast may help distinguish peritoneal tumor implants from adjacent loops of bowel

DIFFERENTIAL DIAGNOSIS Tuberculous (TB) Peritonitis • May be virtually identical in appearance to peritoneal carcinomatosis • Complex, loculated, high-density ascites with omental thickening, hyperenhancement, and nodularity • Less likely to demonstrate discrete nodules or omental caking compared to carcinomatosis • May be associated with other manifestations of abdominal TB, including low-attenuation mesenteric lymphadenopathy, ileocecal mural wall thickening, etc.

Abdominal Mesothelioma • Primary malignant neoplasm arising from peritoneum (2030% of all mesotheliomas) • May be indistinguishable from peritoneal carcinomatosis • Omental stranding, nodularity, discrete masses, or omental caking • Propensity for less ascites than carcinomatosis • Calcified pleural plaques may be clue to correct diagnosis

Peritoneal Lymphomatosis • Peritoneal involvement by lymphoma, most often Burkitt lymphoma, AIDS-related lymphoma, and high-grade lymphomas • Identical to carcinomatosis, with omental/peritoneal nodularity, masses, and omental caking • Usually significant lymphadenopathy throughout abdomen

Primary Peritoneal Serous Papillary Carcinoma • Peritoneal metastases (implants, ascites, omental caking) without primary source of tumor (no ovarian or GI tract primary tumor) ○ Histologically identical to serous ovarian cancer • Identical CT, US, MR findings to carcinomatosis from ovarian carcinoma

Pseudomyxoma Peritonei • Low-density or cystic mucinous implants throughout peritoneum which scallop margins of visceral organs of abdomen (e.g., liver and spleen) ○ May be associated with curvilinear calcification in implants • Most often develops due to perforation of mucinous neoplasm of appendix, but can also develop from dissemination of other mucinous neoplasms

PATHOLOGY General Features • Etiology 146

○ Metastatic disease to peritoneal surfaces, omentum, and mesentery ○ Most commonly arise due to peritoneal cavity spread of surface epithelium tumors (e.g., ovarian carcinoma), although hematogenous spread to peritoneum is also possible – Tumors typically demonstrate peritoneal spread once they gain local access to peritoneum (such as GI tract malignancies which extend though bowel wall and mucosa) ○ Most common malignancies include ovarian and GI tract adenocarcinomas (gastric, colorectal, pancreas, appendix, gallbladder) ○ Less common malignancies to spread to peritoneum include lung, breast, renal cell carcinoma, and sarcoma

• Scalloping of cecum from peritoneal implants • Omental caking may invade transverse mesocolon with nodularity and spiculation of superior contour

Staging, Grading, & Classification • Peritoneal metastases indicate stage IV disease

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ May be asymptomatic if metastases are small or isolated ○ Abdominal distension and pain due to malignant ascites or small bowel obstruction ○ Patients may experience symptoms mimicking bowel obstruction even in absence of true obstruction due to serosal implants on surface of bowel • Clinical profile ○ No reliable lab data ○ In absence of clear primary malignancy on imaging, diagnosis may be made based on positive cytology on paracentesis or positive FNA of omental mass

Demographics • Age ○ Adults; generally > 40 years old (patients with highest risk of developing malignancies) • Epidemiology ○ Varies according to primary tumor

Natural History & Prognosis • Variable depending on individual tumor, but prognosis is very poor in general ○ Typically progressive if untreated ○ Complications: Bowel obstruction, ureteral obstruction

Treatment • Ovarian cancer with peritoneal spread usually treated with cytoreductive surgery followed by chemotherapy • Most other tumors: Combination of systemic and intraperitoneal chemotherapy

SELECTED REFERENCES 1.

Diop AD et al: CT imaging of peritoneal carcinomatosis and its mimics. Diagn Interv Imaging. ePub, 2014

Peritoneal Metastases Peritoneum, Mesentery, and Abdominal Wall

(Left) Axial CECT demonstrates a large mixed cystic/solid mass in the pelvis with adjacent ascites , ultimately found to be a primary ovarian cancer. (Right) Axial CECT in the same patient demonstrates a micronodular pattern of carcinomatosis with ill-defined soft tissue induration studding the omentum with adjacent ascites .

(Left) Axial CECT in a patient with ocular melanoma demonstrates extensive confluent soft tissue in the omentum, compatible with peritoneal carcinomatosis and omental caking. (Right) Color Doppler ultrasound image in the same patient demonstrates extensive soft tissue throughout the omentum with internal color flow vascularity, in keeping with carcinomatosis.

(Left) Axial CECT in an elderly woman demonstrates bilateral cystic and solid masses with adjacent small ascites , ultimately found to represent primary ovarian cancer. (Right) Axial CECT in the same patient demonstrates several discrete nodular soft tissue tumor implants in the omentum, consistent with carcinomatosis.

147

Peritoneum, Mesentery, and Abdominal Wall

Pseudomyxoma Peritonei KEY FACTS

TERMINOLOGY • Diffuse intraperitoneal accumulation of gelatinous mucinous implants due to rupture of appendiceal mucinous neoplasm • Terminology is debated, and some authors also use term pseudomyxoma peritonei (PMP) for mucinous dissemination after rupture of mucin-producing tumors at other sites (i.e., colon, ovary, etc.)

IMAGING • CT: Low-attenuation masses (usually < 20 HU) scattered throughout peritoneum ○ Frequently associated with loculated ascites of similar attenuation to individual implants ○ Implants cause mass effect on liver and spleen, producing characteristic "scalloped" appearance ○ Implants may demonstrate curvilinear calcification ○ Dominant cystic or solid mass often present in right lower quadrant (in expected location of appendix)

(Left) Axial CECT in a patient with a ruptured appendiceal tumor demonstrates large low-density mucinous implants "scalloping" the border of the liver, a characteristic appearance of pseudomyxoma peritonei. At least 1 implant demonstrates peripheral calcification . (Right) Coronal volume-rendered CECT in the same patient demonstrates the full extent of this patient's extensive pseudomyxoma, with implants surrounding the liver and stomach, as well as extending into the pelvis.

(Left) Axial CECT in a patient with pseudomyxoma peritonei after a ruptured appendiceal tumor demonstrates extensive cystic implants throughout the upper abdomen, some of which demonstrate subtle curvilinear calcification . (Right) Coronal volumerendered CECT better demonstrates the extensive nature of this process, with implants filling nearly the entire abdominal cavity. The patient suffered from periodic bowel obstructions and required several different debulking surgeries.

148

○ Metastases to ovary are common, so cystic masses in ovaries may not represent primary ovarian neoplasm ○ Imaging findings of bowel obstruction

PATHOLOGY • Mucin-producing neoplasm of appendix causes appendiceal distension and subsequent perforation with diffuse intraperitoneal spread of mucinous implants

CLINICAL ISSUES • Slowly progressive process with accumulation of implants and development of multiple bowel obstructions • Primary treatment is cytoreductive surgery and infusion of heated intraperitoneal chemotherapy • Survival improved with addition of hyperthermic intraperitoneal chemotherapy to cytoreduction, with 5-year survival as high as 77% and 10-year survival of 57% • Treatment is not curative and is primarily designed to reduce symptoms and prolong survival

Pseudomyxoma Peritonei

Abbreviations • Pseudomyxoma peritonei (PMP)

Definitions • Diffuse intraperitoneal accumulation of gelatinous mucinous implants due to rupture of appendiceal mucinous neoplasm • Terminology is highly debated and variable, and some authors also use the term PMP for mucinous dissemination after rupture of mucin-producing tumors at other sites (i.e., colon, stomach, fallopian tube, ovary, urachus, etc.)

IMAGING General Features • Best diagnostic clue ○ "Scalloping" of liver and spleen by low-attenuation masses • Location ○ Diffuse involvement of peritoneum, with implants often quite extensive ○ Most common locations include greater omentum and bilateral subphrenic spaces (perihepatic/perisplenic) ○ Implants on serosal surface of bowel are much less common than with peritoneal carcinomatosis ○ Classically does not metastasize to any distant organs or lymph nodes (other than ovarian implants) • Size ○ Implants variable in size, with very small or large implants possible

CT Findings • Low-attenuation masses (usually < 20 HU) scattered throughout peritoneum with central displacement of bowel loops ○ Frequently associated with loculated ascites of similar attenuation to individual implants • Implants cause characteristic mass effect on liver and spleen, producing "scalloped" appearance • Undersurface of diaphragm may appear thickened and irregular due to frequent subphrenic implants • Implants may demonstrate curvilinear peripheral calcification • Dominant cystic or solid mass often present in right lower quadrant (in expected location of appendix) • Metastases to ovary are common, so cystic masses in 1 or both ovaries may not necessarily represent primary ovarian neoplasm • Imaging findings of bowel obstruction (dilated small bowel, discrete transition point, and decompressed distal bowel)

MR Findings • Implants usually low signal on T1WI and high signal on T2WI ○ Exact signal characteristics can vary depending on amount of mucin in implants ○ Areas of enhancement within lesions may be visible on T1WI C+ images (more apparent than with CT) • Characteristic "scalloping" of both liver and spleen by perihepatic and perisplenic implants • Larger collections of T2 hyperintense loculated ascites often accompany cystic implants

Nuclear Medicine Findings • PET/CT ○ FDG uptake often present, but variable: Aggressive histologic subtypes tend to have higher FDG uptake, whereas less aggressive forms have lower uptake ○ Limited sensitivity for small implants (particularly < 1 cm)

Radiographic Findings • Radiography ○ Multiple indirect signs of ascites or peritoneal implants – Displacement of bowel loops centrally – Lateral displacement of liver margin and cecum – Pelvic dog's ears sign: Lobulated fluid collections in pelvis on either side of urinary bladder

Ultrasonographic Findings • Mucinous intraperitoneal masses may appear hypoechoic or hyperechoic with no internal color flow vascularity ○ Conglomerate omental masses may appear echogenic and solid on US (despite appearing cystic on CT) • Complex multiseptated ascites with characteristic echogenic foci in ascites (likely due to gelatinous fluid)

Peritoneum, Mesentery, and Abdominal Wall

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT • Protocol advice ○ Positive oral contrast may helpful to distinguish gelatinous implants from bowel loops

DIFFERENTIAL DIAGNOSIS Peritoneal Carcinomatosis Without Mucinous Ascites • Peritoneal metastases most often result from ovarian and GI tract primary tumors • Discrete tumor implants, when visible on imaging, are more often solid in appearance with frequent associated ascites ○ Solid tumor implants may become confluent and develop into large conglomerate omental masses (omental caking) • Very rarely may cause "scalloping" of liver and spleen, but density of implants and known primary malignancy are key to diagnosis

Peritoneal Carcinomatosis With Mucinous Ascites • Some authors use the term PMP for disseminated spread of any mucin-producing neoplasm (not simply cases with appendiceal primary) • Implants may appear low density (with "scalloping" of liver and spleen) and be indistinguishable from classic PMP due to appendiceal primary neoplasm • Primary mucinous ovarian tumors usually present with unilateral dominant pelvic mass, although distinction from PMP often possible only at laparoscopy • Normal appendix may be clue to diagnosis on CT • Appendectomy frequently performed during surgery for presumed metastatic ovarian cancer or mucinous carcinomatosis without known primary in order to exclude PMP

Tuberculosis Peritonitis • Variable amounts of free or loculated complex ascites with infiltration of omentum ± discrete masses 149

Peritoneum, Mesentery, and Abdominal Wall

Pseudomyxoma Peritonei

• Often associated with other evidence of tuberculosis in abdomen, including low-attenuation mesenteric nodes and thickening of cecum and terminal ileum

Bacterial Peritonitis • Ascites ± loculated fluid collections or discrete abscess with smooth thickening and hyperenhancement of peritoneum • Ascites may be slightly higher in attenuation than simple ascites and may demonstrate internal complexity (septations, debris)

Abdominal Mesothelioma • Rare primary malignant neoplasm arising from peritoneum • Omental and peritoneal stranding, nodularity, and discrete masses on CT with variable ascites (usually less ascites than carcinomatosis) • Tumor appears solid, rather than cystic implants seen more frequently with PMP

PATHOLOGY General Features • Etiology ○ Mucin-producing neoplasm of appendix causes appendiceal distension and subsequent perforation with diffuse intraperitoneal spread of mucinous implants ○ Strict definition of PMP encompasses only mucinous dissemination from primary appendiceal tumor ○ Much confusion about terminology, as many authors use the term PMP to refer to intraperitoneal spread of any mucin-producing adenocarcinoma of appendix, ovary, fallopian tube, GI tract, lung, etc. • Genetics ○ No known genetic association

Staging, Grading, & Classification • Ronnet classification (1995) ○ Type I: Adenomucinosis (also known as disseminated peritoneal adenomucinosis or DPAM) – Cytologically bland adenomatous cells and mucin without frank adenocarcinoma and better prognosis □ Some consider it as not truly benign, but representing well-differentiated adenocarcinoma ○ Type II: Mucinous adenocarcinoma (also known as peritoneal mucinous carcinomatosis or PMCA) – Frank adenocarcinoma and mucin with worse prognosis ○ Type III: Intermediate – Mixture of types I and II with combination of adenoma and adenocarcinoma cells with mucin • World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) divided PMP into 2 types: Low-grade mucinous adenocarcinoma and high-grade mucinous adenocarcinoma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most commonly abdominal distension and development of new-onset inguinal hernia ○ Abdominal pain, weight loss 150

○ Patients with more extensive disease may present with symptoms of bowel obstruction ○ Not uncommonly an unexpected finding encountered at surgery performed for other suspected diagnoses (i.e., appendicitis) • Clinical profile ○ Elevated CEA and CA19-9 often present

Demographics • Age ○ Adults with mean age of 53 years • Gender ○ F > M (2-3x more frequent in females) • Ethnicity ○ No known association • Epidemiology ○ Rare, with incidence of 1 per million

Natural History & Prognosis • Slowly progressive process with progressive accumulation of implants and loculated ascites and development of multiple bowel obstructions • Survival has improved with addition of hyperthermic intraperitoneal chemotherapy to standard cytoreduction, with 5-year survival as high as 77% and 10-year survival of 57% • In general, all patients eventually die from this disease

Treatment • Primary treatment is cytoreductive surgery (Sugarbaker procedure) with debulking of intraperitoneal implants and infusion of heated intraperitoneal therapy ○ Complex surgery with significant morbidity (11-21% require reoperation due to complications) and mortality (0-14%) • Some groups have reported using systemic chemotherapy, radiotherapy, or intraperitoneal isotope therapy, although little supportive evidence • Multiple repeat surgeries often required due to progressive disease, and each surgery becomes more difficult due to adhesions and fibrosis • Treatment is not curative and is primarily designed to reduce symptoms and prolong survival

DIAGNOSTIC CHECKLIST Consider • Consider pseudomyxoma peritonei in patients with lowdensity tumor implants throughout abdomen with "scalloping" of liver and spleen • Presence of dominant unilateral ovarian mass in conjunction with mucinous implants in peritoneum makes metastatic ovarian cancer more likely than PMP

SELECTED REFERENCES 1. 2.

Carr NJ: Current concepts in pseudomyxoma peritonei. Ann Pathol. 34(1):913, 2014 Que Y et al: Pseudomyxoma peritonei: some different sonographic findings. Abdom Imaging. 37(5):843-8, 2012

Pseudomyxoma Peritonei Peritoneum, Mesentery, and Abdominal Wall

(Left) Coronal CECT demonstrates the earliest stage of pseudomyxoma peritonei, with a dominant mucinous implant in the right lower quadrant found to be the result of a ruptured appendiceal mucocele. No other implants were present elsewhere. (Right) Sagittal ultrasound in a patient with pseudomyxoma peritonei demonstrates a perihepatic implant . Despite appearing cystic on CECT, implants on US can appear solid or echogenic.

(Left) Axial CECT demonstrates characteristic "scalloping" of the liver by small perihepatic implants . The implants are low density, but slightly higher in attenuation (~ 20 HU) than simple fluid. (Right) Coronal CECT in the same patient demonstrates extensive lowdensity implants occupying a substantial portion of the abdomen. Not surprisingly, the patient suffered from frequent bouts of bowel obstruction.

(Left) Axial CECT in a patient with pseudomyxoma peritonei shows extensive lowattenuation gelatinous masses involving the lesser sac and surrounding the stomach, with more nodular soft tissue infiltration laterally . (Right) Axial CECT in a patient with cystic peritoneal implants from pseudomyxoma peritonei shows calcified perisplenic implants . Calcifications, often curvilinear and peripheral, are not uncommonly seen with implants in pseudomyxoma.

151

Peritoneum, Mesentery, and Abdominal Wall

Eventration and Paralysis of the Diaphragm KEY FACTS

TERMINOLOGY • Eventration: Thinning of diaphragmatic muscle, which still retains its continuity and attachments to costal margin • Paralysis: Properly formed diaphragm that fails to contract

IMAGING • Chest radiograph ○ Eventration: Diaphragmatic contour is eccentric, with upward bulging of affected portion of diaphragm – Usually anteromedial aspect of right hemidiaphragm ○ Paralysis: Asymmetric elevation of involved hemidiaphragm with basal atelectasis • US ○ Sonography superior to fluoroscopy for diaphragmatic abnormalities ○ Diaphragmatic paralysis: No motion or paradoxical motion during inspiration ○ Eventration seen best during inspiration • Chest fluoroscopy

(Left) Coronal CECT demonstrates a focal "hump" or "bulge" in the right hemidiaphragm, characteristic of eventration. Eventration typically occurs in the anteromedial aspect of the right hemidiaphragm. (Right) Sagittal CECT shows focal eventration or thinning of the central portion of the right hemidiaphragm. Compare this with the normal thickness of the more anterior portion of the diaphragm . Note the "mushrooming" of the liver at the site of eventration.

(Left) Coronal CECT demonstrates marked asymmetric elevation of the left hemidiaphragm. (Right) Axial CECT in the same patient demonstrates a soft tissue mass in the expected location of the phrenic nerve (later found to be lymphoma). Diaphragmatic paralysis can occur due to abnormalities in the brain, spinal cord, neuromuscular junction, phrenic nerve, or muscle.

152

○ Paralysis: Movement of affected hemidiaphragm is paradoxical (upward during inspiration or sniff test) – Mediastinum shifts away from paralyzed side during inspiration – Much less sensitive for bilateral paralysis ○ Eventration: Paradoxical motion may or may not be present depending on size of eventration • CT ○ Liver or spleen "mushrooms" through site of eventration

PATHOLOGY • Eventration is a congenital abnormality due to incomplete muscularization of central membranous diaphragm in utero • Paralysis can occur due to abnormalities of brain, spinal cord, neuromuscular junction, phrenic nerve, or muscle

CLINICAL ISSUES • No treatment for asymptomatic patients • Surgical plication of diaphragm for symptomatic patients

Vicarious Excretion

TERMINOLOGY • Excretion of parenterally injected contrast medium by organs other than kidneys

IMAGING • CT Findings ○ High-density material within gallbladder (GB) – CT > 10x more sensitive than radiographs in detecting slight differences in density – Mild to moderate opacification of GB bile on day after CECT or angiogram is a normal and expected finding □ Does not necessarily imply abnormal renal function – Dense opacification on CT indicates renal function ○ Increased attenuation of ascites fluid – Visible a few hours after IV administration of contrast – Results from hepatobiliary and peritoneal contrast excretion into ascites – Mildly increased density of ascites fluid may not indicate renal impairment

– Significantly attenuation suggests renal function ○ Increased attenuation of pericardial fluid – Most common in first few hours after IV contrast – Mildly attenuation can be normal finding • Radiographic findings ○ Opacification of bile within GB after IV contrast always implies impaired or delayed renal function ○ Mild to moderate vicarious excretion is visible on CT in normal patients, but is insufficient to be visible on radiographs ○ Often associated with prolonged nephrograms suggesting acute tubular necrosis or other causes of acute kidney injury

TOP DIFFERENTIAL DIAGNOSES • • • •

Milk of calcium bile, gallstones, or sludge Iatrogenic high density bile due to cholangiography Hemobilia Exudative ascites or hemoperitoneum

Peritoneum, Mesentery, and Abdominal Wall

KEY FACTS

(Left) Radiograph in a patient with acute renal failure following coronary angiography shows dense opacification of the gallbladder bile and both kidneys many hours after the angiogram, compatible with vicarious excretion and shock- or contrast-induced nephropathy. (Right) Axial NECT following embolization of a ruptured splenic artery aneurysm shows dense opacification of bile in the gallbladder and persistent nephrograms (left > right), the latter due to acute tubular necrosis.

(Left) Axial NECT in a patient with sickle cell disease who had a recent angiogram shows persistent opacification of the ureters due to slow excretion from the impaired kidneys. The bile is dense due to vicarious excretion. (Right) Axial NECT a few hours after angiography shows persistent enhancement of the kidneys , compatible with shock- or contrast-induced nephropathy. The ascites measured 60 HU due to vicarious excretion of contrast medium from the peritoneum as a means of compensating for the failed renal excretion.

153

SECTION 3

Esophagus

Introduction and Overview Imaging Approach to the Esophagus

156

Infection Candida Esophagitis Viral Esophagitis Chagas Disease

162 164 165

,QƮDPPDWLRQ 5HƮX[(VRSKDJLWLV Barrett Esophagus Caustic Esophagitis Drug-Induced Esophagitis Radiation Esophagitis Eosinophilic Gastroenteritis and Esophagitis Epidermolysis and Pemphigoid

166 170 172 174 175 176 177

Degenerative Esophageal Webs Cricopharyngeal Achalasia Esophageal Achalasia Esophageal Motility Disturbances Esophageal Scleroderma Schatzki Ring Hiatal Hernia

178 179 180 184 188 192 194

Vascular Disorders Esophageal Varices

198

Esophageal Diverticula Zenker Diverticulum Intramural Pseudodiverticulosis Traction Diverticulum Pulsion Diverticulum

202 206 208 209

Trauma Esophageal Foreign Body Esophageal Perforation Boerhaave Syndrome

210 212 216

Treatment Related Esophagectomy: Ivor Lewis and Other Procedures

218

Benign Neoplasms Intramural Benign Esophageal Tumors Fibrovascular Polyp (VRSKDJHDO,QƮDPPDWRU\3RO\S

224 226 227

Malignant Neoplasms Esophageal Carcinoma Esophageal Metastases and Lymphoma

228 232

Esophagus

Imaging Approach to the Esophagus

Esophageal Anatomy and Terminology The esophagus is a fibromuscular tube about 25 cm long extending from the pharynx to the stomach. It begins at the upper esophageal sphincter, which is formed primarily by the cricopharyngeus muscle. The lower esophageal sphincter (LES) is also known as the phrenic ampulla or the esophageal vestibule and is further defined as the zone of higher resting tone or pressure. The LES is occasionally recognized radiographically as a 2-4 cm long luminal dilation between the esophageal "A" and "B" rings. The A ring is a sporadically imaged indentation of the esophageal lumen at the cephalic end of the LES. The B ring is a transverse mucosal fold that marks the gastroesophageal (GE) junction and often corresponds to the mucosal junction between the epithelium of the esophagus and that of the stomach. The endoscopist often recognizes a "Z" line at this junction, with the esophageal mucosa appearing pearly pink in color and texture, while the gastric mucosa is more textured and deeper in color.

Pharynx The pharynx is essential for effective speech, respiration, and swallowing. The nasopharynx extends from the skull base to the top of the soft palate and lies posterior to the nasal cavity. The oro (mesopharynx) lies between the soft palate and the hyoid bone. It lies posterior to the oral cavity. The hypo (laryngopharynx) extends from the hyoid to the cricopharyngeus muscle. It lies posterior and lateral to the larynx.

Mural Anatomy The esophagus has an internal circular and an outer longitudinal layer of muscle. The upper 1/3 of the esophagus (to about the level of the aortic arch) is composed of striated ("voluntary") muscle, while the lower 2/3 is smooth muscle. The esophagus lacks a serosal coat and is lined by stratified columnar epithelium. The GE junction is attached to the diaphragm by the phrenicoesophageal ligaments (collagenous bands), which tend to weaken and elongate with age, predisposing to hiatal hernia and reflux. The venous drainage of the esophagus is through the azygous system (systemic) and left gastric (portal). Lymphatic drainage is variable, but the upper 2/3 usually drain primarily to the posterior mediastinal nodes, while the lower 1/3 drains to the left gastric and celiac nodes. Overlaps and variations of these patterns are common.

Imaging Protocols Imaging should be tailored to the specific symptom complex. • For dysphagia, choking, aspiration pneumonitis, dysphonia: Modified barium swallow to evaluate motility or plan therapy (usually performed with a speech pathologist); varying consistencies of barium are given by mouth with a recording of swallowing • For odynophagia, evaluation for Barrett esophagus or early cancer: Air-contrast barium esophagram performed using gas-forming crystals to distend esophagus and heavy barium to coat mucosa; procedure is complementary to, or competitive with, endoscopy 156

• For stricture or suspected mass lesion (food sticking in esophagus): Single-contrast barium esophagram using no gas distention and lighter weight barium (complementary to endoscopy) • For suspected reflux (GERD): Barium esophagram using provocative maneuvers to elicit reflux plus pH testing by esophageal probe or capsule • For dysphagia or chest pain possibly related to esophageal dysmotility: Single-contrast esophagram (complementary to esophageal manometry) • For symptoms of dyspepsia, early satiety, abdominal &/or chest pain: Upper GI series with esophageal evaluation (complementary to endoscopy and CT) • For evaluation of depth of esophageal tumor invasion: Endoscopic ultrasonography • For staging known esophageal cancer: PET/CT

Anatomy-Based Imaging Issues Pharyngeal dysfunction is extremely common. Etiologies include cerebrovascular accident, deconditioning, prior surgery, etc. Barium fluoroscopic examinations of the pharynx and esophagus are critical to diagnosing the source of the problem and identifying possible therapeutic endeavors (e.g., modified diet). Gastroesophageal reflux is very common and accounts for the epidemic of GERD and the increasing prevalence of Barrett esophagus, with its attendant risk of adenocarcinoma. Hiatal hernia may result from or cause GERD. Reflux irritates the esophageal mucosa and may interrupt motility with spasm of the longitudinal muscle layer. This leads to a foreshortened esophagus, with the gastric cardia pulled into the thorax (type 1 hernia). Paraesophageal hernias are becoming more common, especially type 3. These are often quite symptomatic and require surgical repair, often involving repair of the large diaphragmatic defect as well as fundoplication. Even with the widespread use of proton-pump inhibitors and other antacids, many patients elect to have surgical intervention for GERD, with fundoplications of various types the most common approach. It is important for radiologists to understand the expected appearance of the esophagus and stomach following fundoplication and to recognize the imaging signs of operative complications. Esophageal cancer is also becoming more common, with a shift in its epidemiology, with adenocarcinoma becoming more prevalent as a direct result of GERD and development of Barrett metaplasia of the esophagus. The lack of a serosal coat allows esophageal cancer to invade adjacent mediastinal structures, and the rich and varied lymphatic and venous drainage predispose to widespread metastases. Accurate staging may require a combination of modalities, including endoscopic sonography (for depth of wall invasion), thoracoabdominal CT, &/or PET/CT. The most common treatment for esophageal carcinoma has become esophagectomy with some form of gastric interposition (Ivor-Lewis or other modification). Once again, familiarity with the expected postoperative findings, as well as its complications, is essential. Esophageal dysmotility has also become more prevalent with the aging population, and imaging plays a major role in its

Imaging Approach to the Esophagus

Esophageal dysmotility accounts for nearly all pulsion diverticula of the pharynx or esophagus. Effective therapy often depends on recognition and intervention for the underlying motility disorder. Esophagitis may result from several infectious, inflammatory, and other causes. Clinical history, physical findings, and esophagoscopy often obviate imaging evaluation, such as for Candida esophagitis in an immunosuppressed patient. However, imaging can play a primary role in diagnosing and "staging" other forms of esophagitis, such as medication induced, radiation, or caustic. Esophageal perforation may result from surgery, endoscopy (most cases), or may be spontaneous (Boerhaave syndrome). Regardless of the etiology, prompt diagnosis and intervention are essential to avoid major morbidity and mortality.

Differential Diagnosis Intraluminal Mass, Esophagus Common • Esophageal carcinoma • Esophageal foreign body • Intramural benign esophageal tumors Less Common • Thrombosed esophageal varix • Inflammatory polyp, esophagus • Candida esophagitis • Viral esophagitis • Papilloma, esophagus Rare but Important • Fibrovascular polyp • Esophageal metastases and lymphoma • Esophageal adenoma Extrinsic Mass, Esophagus Common • Left main bronchus • Aortic arch • Aortic aneurysm • Heart • Cervical osteophytes • Hiatal hernia • Mediastinal lymph nodes • Aberrant right subclavian artery • Metastases and lymphoma, esophageal • Enlarged thyroid Less Common • Intramural benign esophageal tumors • Esophageal carcinoma (mimic) • Gastric carcinoma (mimic) • Bronchogenic cyst • Esophageal varices Lesion at Pharyngoesophageal Junction Common • Achalasia, cricopharyngeal • Cervical osteophytes Less Common • Esophageal webs

• Esophageal carcinoma • Esophagitis, drug-induced • Neck mass Esophageal Ulceration Common • Reflux esophagitis • Candida esophagitis • Drug-induced esophagitis • Viral esophagitis

Esophagus

evaluation, being complementary to manometry. Proper characterization of the type and degree of dysmotility helps in planning effective therapy, such as a Heller myotomy for achalasia or a modified fundoplication for scleroderma of the esophagus.

Less Common • Caustic esophagitis • Radiation esophagitis • Nasogastric intubation • Crohn disease Rare but Important • Behçet disease • Epidermolysis bullosa dystrophica and pemphigoid Esophageal Strictures Common • Reflux esophagitis • Barrett esophagus • Esophageal carcinoma • Scleroderma, esophagus Less Common • Esophageal metastases and lymphoma • Radiation esophagitis • Caustic esophagitis • Drug-induced esophagitis • Candida esophagitis • Nasogastric intubation Rare but Important • Crohn disease • Graft-vs.-host disease (GVHD) • Glutaraldehyde-induced injury • Epidermolysis and pemphigoid • Esophagitis, eosinophilic Dilated Esophagus Common • Achalasia, esophagus • Scleroderma, esophagus • Post-vagotomy state • Fundoplication complications • Reflux esophagitis • Esophageal carcinoma • Hiatal hernia (mimic) • Post-esophagectomy (mimic) Less Common • Gastric carcinoma • Metastases and lymphoma, esophageal • Chagas disease Esophageal Outpouchings (Diverticula) Common • Zenker diverticulum • Traction diverticulum • Pulsion diverticulum • Hiatal hernia (mimic) • Post-esophagectomy (mimic) • Fundoplication complications (mimic) Less Common • Killian-Jamieson diverticulum • Intramural pseudodiverticulosis 157

Esophagus

Imaging Approach to the Esophagus

Esophageal Dysmotility Common • Presbyesophagus • Diffuse esophageal spasm • Achalasia, esophagus • Scleroderma, esophagus • Reflux esophagitis • Fundoplication complications • Post-vagotomy state

Less Common • Caustic esophagitis • Radiation esophagitis

Less Common • Neuromuscular disorders • Esophageal carcinoma • Gastric carcinoma

3.

Odynophagia Common • Pharyngitis • Reflux esophagitis • Candida esophagitis • Viral esophagitis • Drug-induced esophagitis

(Left) Graphic shows the nasopharynx (A, purple, base of skull to palate), oropharynx (B, blue, palate to base of epiglottis), hypopharynx, (C, green, epiglottis to cricopharyngeus), and esophagus (D, below cricopharyngeus muscle). The cricopharyngeal muscle usually lies at the C5-6 level. (Right) Graphic shows normal esophageal landmarks and anatomy. The lower esophageal sphincter extends from the "A" to the "B" ring and is sometimes referred to as the phrenic ampulla, or vestibule.

(Left) Spot film from an esophagram shows the lower esophageal sphincter, marked by the "A" ring proximally and the "B" ring distally. Just below the "B" ring is the herniated portion of the gastric cardia . (Right) Spot film from an esophagram shows a type 1 hiatal hernia above the diaphragm . The esophagus is shortened, probably due to esophagitis and spasm of the longitudinal muscles. GE reflux was demonstrated. The "B" ring marks the GE junction .

158

• Esophageal foreign body

• Boerhaave syndrome (mimic)

Selected References 1. 2.

4.

Goldberg MF et al: Diffuse esophageal spasm: CT findings in seven patients. AJR Am J Roentgenol. 191(3):758-63, 2008 Nguyen NP et al: Prevalence of pharyngeal and esophageal stenosis following radiation for head and neck cancer. J Otolaryngol Head Neck Surg. 37(2):219-24, 2008 Fry LC et al: Incidence, clinical management and outcomes of esophageal perforations after endoscopic dilatation. Z Gastroenterol. 45(11):1180-4, 2007 Dibble C et al: Detection of reflux esophagitis on double-contrast esophagrams and endoscopy using the histologic findings as the gold standard. Abdom Imaging. 29(4):421-5, 2004

Imaging Approach to the Esophagus Esophagus

Outer longitudinal muscle layer Inner circular muscle layer

Phrenicoesophageal ligament (ascending leaf) Diaphragm

Thickened muscle of LES

Phrenicoesophageal ligament (descending leaf) "Z" line

Right crus of diaphragm

Circular muscle layer of stomach

(Top) The esophagus is about 25 cm long and extends from the level of the cricopharyngeus muscle (at the C5-6 level) to the GE junction (at about the T10-11 level). Note the relationship between the esophagus and adjacent structures, including the heart, which may indent or displace the esophageal lumen. The mid esophagus is normally indented by the aortic arch and the left main bronchus. The esophageal hiatus is often at the level of the T10 vertebra. (Bottom) The esophageal wall musculature consists of an inner circular layer and an outer longitudinal layer. In the region of the lower esophageal sphincter (LES), the muscle layers are thickened. The "Z" line marks the junction of the esophageal and gastric mucosa.

159

Esophagus

Imaging Approach to the Esophagus

(Left) This woman had dysphagia with "food sticking in her throat." A film from a rapid sequence filming of the pharynx during swallowing shows prominence and spasm of the cricopharyngeal muscle at the level of the C5-6 vertebral disk space. (Right) Film of the lower esophagus in the same patient shows a type 1 hiatal hernia , a patulous GE junction , and free reflux. In this patient, cricopharyngeal achalasia is probably related to reflux esophagitis and the dysmotility that often accompanies GERD.

(Left) Spot film from an upper GI series demonstrates a type 3 paraesophageal hernia, in which the GE junction and fundus lie within the thorax. The herniated stomach is pinched at the esophageal hiatus . (Right) Two views from an esophagram in an elderly man with dysphagia demonstrate deep, nonpropulsive, tertiary contractions , imparting a "corkscrew" appearance to the esophagus. There is a persistent large outpouching from the mid esophagus representing a pulsion diverticulum.

(Left) Spot film from a barium esophagram shows a shortened and strictured esophagus, with the proximal stomach pulled into the chest. This benign-appearing stricture was due to caustic ingestion. (Right) Spot film from an esophagram shows an "apple core" lesion of the distal esophagus representing carcinoma. There is an abrupt transition, or shoulder, at the proximal end of the tumor as it abuts normal esophagus.

160

Imaging Approach to the Esophagus Esophagus

(Left) This patient had a partial esophagectomy with gastric pull-through for esophageal carcinoma. An upright film from an esophagram shows a dilated gastric conduit with bariumfluid-air levels indicating delayed emptying. The stomach is narrowed as it traverses the diaphragm . The abdominal portion of the stomach is normal. (Right) CT in a similar case shows a dilated, fluid-distended gastric conduit , along with bilateral pleural effusions and airspace consolidation due to aspiration pneumonia.

(Left) This elderly man had a recent esophagectomy for carcinoma. Spot film from an esophagram shows displacement of the gastric conduit to the right and a leak of contrast from the esophagogastric anastomosis . (Right) Coronal CT in the same case shows the leak extending into the mediastinum.

(Left) Following a recent fundoplication this patient was evaluated by esophagography. Spot film shows the expected compression by an intact fundal wrap, but also shows extravasated gas and contrast material into the mediastinum. (Right) CT in the same case shows mediastinal gas and fluid due to perforation of the wrap or distal esophagus.

161

Esophagus

Candida Esophagitis KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Esophageal candidiasis, moniliasis • Infectious esophagitis caused by fungi of Candida species, usually Candida albicans

• Odynophagia (sharp pain on swallowing) • Immunocompromised patients ○ Occurs in patients with AIDS, hematologic malignancies • Other patients with physiologic or mechanical obstruction of esophagus and local stasis (e.g., achalasia) • Usually self-limited with rapid response to oral therapy

IMAGING • Double-contrast esophagram ○ Mucosal plaques in immunocompromised patients ○ Predominantly mid or upper esophagus ○ Plaques: Several mm in size, usually < 1 cm ○ Longitudinally oriented plaques ○ 90% sensitivity in detecting Candida esophagitis

PATHOLOGY • Most common cause of infectious esophagitis ○ Only 50% of patients with Candida esophagitis are found to have thrush

(Left) Graphic shows longitudinally oriented mucosal plaques characteristic of Candida esophagitis. (Right) Double-contrast barium esophagram shows longitudinally oriented filling defects representing Candida plaques . This modality is quite accurate in depicting the characteristic mucosal plaques, ulcers, and less common manifestations of Candida esophagitis. However, in most patients, the combination of odynophagia and oral thrush is sufficient to make the diagnosis and begin treatment.

(Left) Esophagram shows a shaggy appearance of the esophagus due to ulcers and raised plaques. Note the innumerable pseudodiverticula , which are narrow, flaskshaped dilations of excretory ducts. These nonspecific findings have also been observed in patients with chronic esophagitis or dysmotility syndromes. (Right) Esophagram shows a severely irregular surface pattern, due to innumerable plaques and ulcers. A mild stricture was present in the upper esophagus (not shown).

162

DIAGNOSTIC CHECKLIST • Odynophagia with plaques in immunocompromised patient should suggest candidiasis • Plaques are raised mucosal lesions; if central contrast collection is present then lesion is ulcer • Oral thrush plus odynophagia is presumptive evidence of Candida esophagitis

Candida Esophagitis

Synonyms • Esophageal candidiasis, moniliasis

Definitions • Infectious esophagitis caused by fungi of Candida species, usually Candida albicans

IMAGING General Features • Best diagnostic clue ○ Mucosal plaques in immunocompromised patient • Location ○ Any part or entire esophagus

Fluoroscopic Findings • Double-contrast esophagram ○ Discrete plaques with longitudinal orientation – Plaques are raised mucosal lesions (filling defects in barium pool); if there is central collection of barium, then lesion is an ulcer ○ "Cobblestone" or "snakeskin" appearance with confluent plaques ○ Severe cases: Deep ulcers ○ Foamy esophagus, usually in scleroderma or achalasia patients (bubbles of gas released by yeast)

CT Findings • CECT ○ Uniform circumferential wall thickening (> 5 mm)

Imaging Recommendations • Best imaging tool ○ Double-contrast esophagram – 90% sensitivity in detecting Candida esophagitis

DIFFERENTIAL DIAGNOSIS Reflux Esophagitis • Ulcers, strictures in distal esophagus

Viral Esophagitis • Usually flat ulcerations on normal mucosa • Advanced cases may have exudate simulating Candida

Superficial Spreading Carcinoma • Confluent nodules without intervening normal mucosa

Esophagus

○ Oral thrush – Oral candidiasis and odynophagia: 71-100% positive predictive value for Candida esophagitis – Only 50% of patients with esophageal candidiasis have oral thrush ○ Esophageal intramural pseudodiverticulosis – Candidiasis likely represents superinfection secondary to stasis in pseudodiverticula

TERMINOLOGY

Gross Pathologic & Surgical Features • Patchy, creamy white, small (< 1 cm) plaques on friable erythematous mucosa ○ Plaques represent necrotic epithelial debris &/or Candida colonies • Advanced cases ○ Ulcerated, necrotic mucosa with pseudomembranes ○ May lead to esophageal stricture, perforation, or even fistula into aorta

Microscopic Features • Tissue invasion by fungal mycelia seen on endoscopic mucosal biopsy • Budding yeast cells, hyphae, and pseudohyphae on silver stain, PAS stain, or Gram stain

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Odynophagia (sharp pain on swallowing) • Clinical profile ○ Immunocompromised patients – AIDS, transplantation, hematologic malignancies ○ Patients with physiologic or mechanical obstruction of esophagus and local stasis – Scleroderma, achalasia, esophageal strictures ○ Can occasionally occur in immunocompetent patients ○ Chronic proton-pump inhibitor therapy may be predisposing factor

Demographics • AIDS with CD4 cell counts below 200 cells/μL

Natural History & Prognosis • Usually rapid response to antifungal therapy

Treatment • Oral antifungals: Ketoconazole or fluconazole • Amphotericin-B for treatment failures or recurrences

Glycogenic Acanthosis • In elderly individuals with no esophageal symptoms • Mucosal plaques or nodules more uniform, rounded, and less well defined than candidiasis

PATHOLOGY General Features • Etiology ○ Most common cause of infectious esophagitis – Downward spread of Candida albicans from mouth to esophagus • Associated abnormalities ○ May coexist with herpes or CMV esophagitis

DIAGNOSTIC CHECKLIST Consider • Odynophagia with plaques in immunocompromised patient should suggest candidiasis

SELECTED REFERENCES 1. 2.

Kim KY et al: Acid suppression therapy as a risk factor for Candida esophagitis. Dig Dis Sci. 58(5):1282-6, 2013 Hyun JJ et al: Candida esophagitis complicated by esophageal stricture. Endoscopy. 42 Suppl 2:E180-1, 2010

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Esophagus

Viral Esophagitis KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Inflammation of esophagus due to viral infection

• Odynophagia is most common presenting symptom • Herpes: Usually in immunocompromised patients but can occur in otherwise healthy patients ○ Especially in sexual partners of patients with active herpes infection • Treatment ○ Analgesics for odynophagia ○ Antiviral therapy for CMV, VZV, and persistent herpes

IMAGING • Double-contrast esophagram is best imaging study ○ Herpes: Multiple small, discrete, punched-out ulcers on background of normal mucosa ○ CMV and HIV: 1 or more large, flat ulcers ○ HPV: Multiple papillary excrescences ○ EBV: Deep, linear ulcers

TOP DIFFERENTIAL DIAGNOSES • Candida, reflux, or drug-induced esophagitis

PATHOLOGY • Impaired immune surveillance: Radiation and chemotherapy render esophageal mucosa vulnerable to infection

(Left) Spot film from esophagram shows tiny ulcers surrounded by a radiolucent halo of edematous mucosa in a patient with herpes esophagitis. Ulcers are seen en face and in profile . (Right) Double-contrast esophagram shows elongated plaques in a patient with herpes esophagitis. The findings are indistinguishable from Candida esophagitis.

(Left) Barium esophagram film demonstrates at least 1 large superficial ulcer in this biopsy-proven HIV-induced ulceration. Giant superficial esophageal ulcers are usually caused by cytomegalovirus or HIV in the setting of AIDS. (Right) Double-contrast esophagram film shows clusters of nodules due to a human papillomavirus infection, findings typical of squamous papillomatosis.

164

DIAGNOSTIC CHECKLIST • Small discrete, or large shallow ulcers should suggest viral esophagitis in immunocompromised patients with odynophagia • Careful analysis of double-contrast patterns is necessary to distinguish plaques from ulcers

Chagas Disease

TERMINOLOGY • Trypanosomiasis

IMAGING • Cardiomegaly • Esophageal "pseudoachalasia" ○ Aperistalsis ○ Dilation of lumen • Megaduodenum ○ Aperistalsis; dilated lumen • Small bowel dilation ○ With delayed transit • Megacolon ○ Striking elongation and dilation ○ Especially rectosigmoid and descending colon

TOP DIFFERENTIAL DIAGNOSES

Esophagus

KEY FACTS • Myxedema • Amyloidosis • Neuropathies ○ Diabetes ○ Porphyria ○ Thiamine deficiency

PATHOLOGY • Neurotoxin from protozoan parasite Trypanosoma cruzi attacks autonomic ganglion cells

CLINICAL ISSUES • Spread by bite of reduviid bug • Endemic in Central America, Brazil, northern Argentina, Venezuela ○ Affects millions of patients in these countries • Reported in southern USA

• Achalasia • Scleroderma

(Left) Esophagram in a 56year-old woman with known Chagas disease (who had recently complained of dysphagia) shows decreased esophageal motility with mild narrowing at the gastroesophageal junction . The esophagus is only mildly dilated. (Right) Esophagram shows esophageal dilatation. Esophageal contractions were seen during fluoroscopy, but there was failure of the lower esophageal sphincter to relax.

(Left) Esophagram on a 48year-old man from Brazil with known Chagas disease shows esophageal dilatation with abrupt tapering at the gastroesophageal junction and lack of peristalsis. The degree of esophageal involvement in Chagas disease is quite variable, ranging from normal to megaesophagus. (Right) PA radiograph shows global cardiomegaly and clear lung fields in a patient with chronic cardiomyopathy from Chagas disease. There is no evidence of pulmonary congestion or pleural effusion.

165

Esophagus

Reflux Esophagitis KEY FACTS

TERMINOLOGY • Inflammation of esophageal mucosa due to gastroesophageal (GE) reflux

• Viral esophagitis • Candida esophagitis • Caustic esophagitis

IMAGING

PATHOLOGY

• Mucosal nodularity: Fine nodular, granular, or discrete plaques • Irregular ulcerated mucosa of distal esophagus • Foreshortening of esophagus: Due to muscle spasm • Inflammatory esophagogastric polyps: Smooth, ovoid elevations • Hiatal hernia in > 95% of patients with stricture ○ Probably result and not cause of reflux • Peptic stricture (1-4 cm length): Concentric, smooth, tapered narrowing of distal esophagus

• Lower esophageal sphincter (LES): Decreased tone leads to increased reflux • Hydrochloric acid (HCl) and pepsin: Synergistic effect

TOP DIFFERENTIAL DIAGNOSES • Scleroderma • Drug-induced esophagitis

(Left) Graphic shows a small type 1 (sliding) hiatal hernia, associated with foreshortening of the esophagus, ulceration of the mucosa, and tapered stricture of the distal esophagus. (Right) Film from an aircontrast esophagram demonstrates a small hiatal hernia , foreshortening of the esophagus, and a mild stricture at the gastroesophageal (GE) junction. There are several subtle esophageal ulcers at the level of the stricture.

(Left) Spot film from a barium esophagram shows a small hiatal hernia. Note the gastric folds extending above the diaphragm. The esophagus appears shortened, presumably due to spasm of the longitudinal muscles within its wall. A stricture is present at the GE junction, and persistent collections of barium indicate mucosal ulceration . (Right) An esophagram in the same patient shows that a 13 mm barium-impregnated pill cannot pass through the peptic stricture.

166

CLINICAL ISSUES • 15-20% of Americans have heartburn due to reflux ○ Prevalence of GERD has increased sharply with obesity epidemic • Symptoms: Heartburn, regurgitation, angina-like pain ○ Dysphagia, odynophagia • Confirmatory testing: Manometric/ambulatory pHmonitoring techniques ○ Endoscopy, biopsy, and histological studies

Reflux Esophagitis

Definitions • Inflammation of esophageal mucosa due to gastroesophageal (GE) reflux

IMAGING General Features • Best diagnostic clue ○ Irregular ulcerated mucosa of distal esophagus on barium esophagram ○ Most common sign – Finely nodular or granular appearance with poorly defined radiolucencies that fade peripherally due to edema and inflammation of mucosa • Location ○ Distal 1/3 or 1/2 of esophagus • Other general features ○ Complication of gastroesophageal reflux disease (GERD) ○ Based on onset, classified clinically and radiologically – Acute or chronic reflux esophagitis ○ Severity of reflux esophagitis – Depends on intrinsic resistance of mucosa

Radiographic Findings • Double-contrast esophagography ○ Acute reflux esophagitis – Decreased primary wave of peristalsis with increased tertiary contractions – Mucosal nodularity □ Fine nodular, granular, or discrete plaque-like defects (pseudomembranes) – Foreshortening of esophagus □ Due to spasm of longitudinal muscles □ Not necessarily fibrotic stricture – Ulcers □ Single or multiple tiny collections of barium with surrounding mounds of edematous mucosa □ Radiating and puckering of folds □ Usually at or near GE junction – Thickened vertical or transverse folds (> 3 mm) ○ Chronic or advanced reflux esophagitis – Decreased distal esophageal distensibility with irregular, serrated contour (due to ulceration/edema/spasm) □ Due to ulceration, edema, or spasm – Sacculations and pseudodiverticula may be seen – Peptic stricture (1-4 cm length/0.2-2 cm width) □ Concentric smooth-tapered narrowing of distal esophagus with proximal (upstream) dilatation □ Some may resemble Schatzki rings, but are generally thicker – "Stepladder" appearance □ Transverse folds due to vertical scarring – Hiatal hernia □ Seen in > 95% of patients with peptic stricture □ Probably result and not cause of reflux – Inflammatory pseudopolyp □ Single enlarged fold arising at GE junction

□ No malignant potential but may need endoscopy with biopsy to rule out cancer

CT Findings

Esophagus

TERMINOLOGY

• CECT ○ Target sign: Combination of esophageal mucosal enhancement and surrounding hypodense submucosa ○ Hiatal hernia usually evident

Imaging Recommendations • Videofluoroscopic double-contrast esophagram ○ En face and profile views ○ 90% sensitivity • Biphasic examination with upright double-contrast and prone single-contrast views of esophagus • Include provocative maneuvers to test for reflux ○ Not always evident on esophagram in spite of other evidence of reflux esophagitis ○ Perform with fluoroscopy table horizontal ○ Roll patient back and forth

DIFFERENTIAL DIAGNOSIS Scleroderma • Also results in decreased peristalsis, distal esophageal stricture • Diminished peristalsis is earlier and more prominent feature in scleroderma • Correlation with skin changes of scleroderma usually allows diagnosis

Drug-Induced Esophagitis • Usually abrupt onset of odynophagia • Ulceration &/or stricture in upper esophagus at sites of narrowing ○ e.g., at aortic arch indentation • Usually not associated with hiatal hernia or foreshortened esophagus

Viral Esophagitis • Usually in immunocompromised patients • Small or large shallow ulcers on background of normal mucosa • Usually no hiatal hernia, reflux, or stricture

Candida Esophagitis • Usually in immunocompromised patients • Usually more raised plaques than ulceration • No associated hiatal hernia, reflux, or stricture

Caustic Esophagitis • History of caustic ingestion is key • Strictures are usually more severe and longer than with peptic strictures

PATHOLOGY General Features • Etiology ○ GERD – Irritants: Drugs, alcohol, smoking – Obesity and tight clothing provoke reflux ○ Pathogenesis of reflux esophagitis 167

Esophagus

Reflux Esophagitis

– Lower esophageal sphincter (LES) □ Decreased tone leads to increased reflux – Hydrochloric acid (HCl) and pepsin □ Synergistic effect producing more injury than HCl alone

Staging, Grading, & Classification • Double-contrast esophagrams can classify risk for Barrett esophagus ○ Low risk: No structural abnormalities (regardless of presence/absence of reflux or hiatal hernia) – Can treat empirically without endoscopy ○ Moderate risk: Esophagitis or short peptic strictures in distal esophagus – Endoscopy based on severity of symptoms, age, and health of patient ○ High risk: Midesophageal, long (> 3 cm) stricture, ulcer, or reticular pattern of mucosa – Endoscopy with biopsy for possible Barrett esophagus

Gross Pathologic & Surgical Features • Hyperemia, inflammation • Superficial ulceration, necrosis, white plaques, strictures

Microscopic Features • • • •

Thinning of stratified squamous epithelium Superficial necrosis and ulceration Basal cell hyperplasia, edema Submucosal polymorphonuclear leukocyte infiltrate

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Heartburn, regurgitation, angina-like pain ○ Dysphagia, odynophagia • Lab data ○ Manometric/ambulatory pH-monitoring techniques – Reveal increased presence of acid in esophagus – Often decreased esophageal peristalsis • Diagnosis ○ Endoscopy, biopsy, and histological studies

Demographics

168

– Longitudinal esophageal shortening (muscle spasm, not fibrosis) – Disruption of ligaments surrounding GE junction □ Pulls gastric fundus into thorax ○ Barrett esophagus/adenocarcinoma • Prognosis ○ Acute reflux esophagitis: Good ○ Chronic reflux esophagitis: Poor without treatment

Treatment • • • • •

H2 receptor antagonists, proton-pump inhibitors Antacids, cessation of irritants Weight loss for obese patients Metoclopramide: Increases LES tone Surgery (fundoplication)

DIAGNOSTIC CHECKLIST Consider • Differentiate from other types of esophagitis

Image Interpretation Pearls • Smooth, tapered, concentric narrowing in distal esophagus above hiatal hernia is diagnostic of peptic stricture due to reflux esophagitis

SELECTED REFERENCES 1.

2.

3.

4. 5.

6. 7.

8.

• Age ○ Usually middle-aged adults • Gender ○ M=F • Epidemiology ○ 15-20% of Americans have heartburn due to reflux ○ Prevalence of GERD has increased sharply with obesity epidemic

9.

Natural History & Prognosis

14.

• Some degree of GE reflux is considered normal ○ GERD implies damage to esophagus or symptoms that interfere with quality of life • Complications ○ Ulceration, bleeding, stenosis ○ Sliding hiatal hernia due to – Inflammation of mucosa

15.

10.

11. 12. 13.

16. 17.

Li B et al: Reducing the gastroesophageal reflux with lip-type reinforcement technique during intrathoracic esophagogastrostomy. Hepatogastroenterology. 60(127):1541-6, 2013 Pelechas E et al: Gastroesophageal reflux disease: epidemiological data, symptomatology and risk factors. Rev Med Chir Soc Med Nat Iasi. 117(1):1838, 2013 Zagari RM et al: Gastro-oesophageal reflux symptoms, oesophagitis and Barrett's oesophagus in the general population: the Loiano-Monghidoro study. Gut. 57(10):1354-9, 2008 Moayyedi P et al: Gastro-oesophageal reflux disease. Lancet. 367(9528):2086-100, 2006 Vakil N et al: The Montreal definition and classification of gastroesophageal reflux disease: a global evidence-based consensus. Am J Gastroenterol. 101(8):1900-20; quiz 1943, 2006 Levine MS et al: Diseases of the esophagus: diagnosis with esophagography. Radiology. 237(2):414-27, 2005 Dibble C et al: Detection of reflux esophagitis on double-contrast esophagrams and endoscopy using the histologic findings as the gold standard. Abdom Imaging. 29(4):421-5, 2004 Hu C et al: Solitary ulcers in reflux esophagitis: radiographic findings. Abdom Imaging. 22(1):5-7, 1997 Levine MS: Reflux esophagitis and Barrett's esophagus. Semin Roentgenol. 29(4):332-40, 1994 Thompson JK et al: Detection of gastroesophageal reflux: value of barium studies compared with 24-hr pH monitoring. AJR Am J Roentgenol. 162(3):621-6, 1994 Levine MS: Radiology of esophagitis: a pattern approach. Radiology. 179(1):1-7, 1991 Levine MS et al: Update on esophageal radiology. AJR Am J Roentgenol. 155(5):933-41, 1990 Mann NS et al: Barrett's esophagus in patients with symptomatic reflux esophagitis. Am J Gastroenterol. 84(12):1494-6, 1989 Levine MS et al: Pseudomembranes in reflux esophagitis. Radiology. 159(1):43-5, 1986 Levine MS et al: Fixed transverse folds in the esophagus: a sign of reflux esophagitis. AJR Am J Roentgenol. 143(2):275-8, 1984 Creteur V et al: The role of single and double-contrast radiography in the diagnosis of reflux esophagitis. Radiology. 147(1):71-5, 1983 Graziani L et al: Reflux esophagitis: radiologic-endoscopic correlation in 39 symptomatic cases. Gastrointest Radiol. 8(1):1-6, 1983

Reflux Esophagitis Esophagus

(Left) Supine spot film from a barium esophagram demonstrates free and repeated reflux and a stricture at the GE junction. Tertiary contractions and diminished primary peristalsis were also noted during fluoroscopy. (Right) The stricture at the GE junction is again noted on this prone film from the esophagram. Tertiary contractions are also seen.

(Left) Two views from a barium esophagram demonstrate a small hiatal hernia and a stricture at the GE junction. Endoscopic biopsy of the strictured lesion was performed to rule out Barrett metaplasia. (Right) Following biopsy, a repeat esophagram (with watersoluble contrast medium) shows a contained leak from the biopsy site. Leaks such as this can also result from balloon dilation of strictures.

(Left) Prone film from an esophagram shows a tight stricture just above the GE junction with upstream dilation of the esophagus. The herniated stomach is pulled taut as a result of the foreshortening of the esophagus, a common and important sign of reflux esophagitis. (Right) Endoscopic image of the distal esophagus in the same patient demonstrates pseudomembranes , mucosal ulceration , nodularity, and stricture.

169

Esophagus

Barrett Esophagus KEY FACTS

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Mid esophageal stricture with hiatal hernia and reflux is essentially pathognomonic • Long segment: Columnar epithelium > 3 cm above gastroesophageal (GE) junction ○ Due to more severe reflux disease ○ Hiatal hernia in almost all patients ○ Mid esophageal mucosal irregularity, stricture, deep ulceration ○ Risk of cancer > short-segment type • Short segment: Columnar epithelium 3 cm above GE junction ○ More common than long segment (reported in 2-12% of patients with chronic reflux at endoscopy) ○ Due to less severe reflux disease ○ Distal esophageal reticular mucosa, ± stricture, ± shallow ulceration

• • • • • • • •

(Left) Graphic shows a type 1 hiatal hernia, distal esophageal stricture, and nodular mucosal surface. Note the discrete ulcer and an adenocarcinoma represented by a raised sessile lesion with an irregular surface. (Right) 2 views from an esophagram show a mid esophageal stricture and ulcer in a patient with a small hernia and reflux.

(Left) Endoscopic image shows a large ulcer with the velvet texture of Barrett mucosa and stricture. Normal esophageal mucosa has a shiny, smooth, pink surface. (Right) Two views from an esophagram show a polypoid mass that represents an adenocarcinoma arising in Barrett mucosa.

170

Esophageal carcinoma Reflux esophagitis Candida esophagitis Viral esophagitis Radiation esophagitis Caustic esophagitis Drug-induced esophagitis Scleroderma

CLINICAL ISSUES • Risk of adenocarcinoma based on morphology ○ High risk: Midesophageal stricture, ulcer, reticular mucosa ○ Moderate risk: Distal peptic stricture and reflux esophagitis ○ Low risk: If none of above findings are present • Diagnosis: Endoscopy with biopsy

Barrett Esophagus

Definitions • Metaplasia of distal esophageal squamous epithelium to columnar epithelium

IMAGING General Features • Best diagnostic clue ○ Mid esophageal stricture with hiatal hernia and reflux is essentially pathognomonic

Gross Pathologic & Surgical Features • Velvety, pinkish-red columnar mucosa

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Reflux symptoms – "Heartburn," and angina-like pain – 20-40% of patients are asymptomatic • Diagnosis ○ Endoscopy, biopsy, and histopathology

Radiographic Findings

Demographics

• Double contrast esophagography is imaging of choice • Classified into 2 types based on endoscopy and histopathologic findings ○ Long segment: Columnar epithelium > 3 cm above gastroesophageal (GE) junction – Due to more severe reflux disease – Hiatal hernia in almost all patients – Mid esophageal mucosal irregularity, stricture, ulceration – Greater cancer risk in long- vs. short-segment type ○ Short segment: Columnar epithelium 3 cm above GE junction – Due to less severe reflux disease – Hiatal hernia present in 72% of patients

• Age ○ Mean: 55-65 years; prevalence increases with age • Gender ○ M:F = 2:1 • Ethnicity ○ Caucasians > African Americans (10:1) • Epidemiology ○ Prevalence: 2-12 % of patients with reflux esophagitis ○ Increased risk of adenocarcinoma in Barrett mucosa – Estimated 30-40x higher risk than general population – Accounts for almost all cases of adenocarcinoma

DIFFERENTIAL DIAGNOSIS Esophageal Carcinoma • Asymmetric contour with abrupt proximal borders ("rat tail" appearance)

Esophagitis • Reflux esophagitis ○ May be impossible to distinguish from short-segment Barrett esophagus on imaging • Candida esophagitis ○ Multiple tiny, round lucencies ± ulcers • Viral esophagitis ○ Superficial ulcers on normal mucosa ○ Usually in immunocompromised patients • Caustic esophagitis ○ Long ulceration and stricture ○ Diagnosis: History and endoscopic biopsy • Drug-induced esophagitis ○ Acute onset of odynophagia with ulceration and spasm ○ Diagnosis made by imaging and classic history

Scleroderma • Aperistalsis, dilated esophagus, patulous or strictured GE junction

PATHOLOGY

Treatment • Medical (nonoperative): Antacids, cessation of irritants • Surgical ○ Fundoplication to prevent reflux ○ Partial esophagectomy for long-segment Barrett esophagus with severe ulceration, stricture, or dysplasia

Clinical Features • Risk of adenocarcinoma based on morphology ○ High risk: Midesophageal stricture, ulcer, reticular mucosa ○ Moderate risk: Distal peptic stricture and reflux esophagitis ○ Low risk: If none of above findings are present • Diagnosis: Endoscopy with biopsy

DIAGNOSTIC CHECKLIST Consider • Rule out other causes of esophageal stricture ± ulceration; consider carcinoma

Image Interpretation Pearls • Long to mid esophageal or short distal esophageal stricture/ulcer associated with hiatal hernia/GE reflux

SELECTED REFERENCES 1. 2.

General Features • Etiology ○ Chronic GE reflux of acid and pepsin with chronic esophagitis – Re-epithelialization by pluripotent stem cells □ Differentiate into gastric or intestinal epithelium

Esophagus

TERMINOLOGY

3.

Dunbar KB et al: Controversies in Barrett Esophagus. Mayo Clin Proc. ePub, 2014 Melson J et al: Negative surveillance endoscopy occurs frequently in patients with short-segment non-dysplastic Barrett's esophagus. Dis Esophagus. ePub, 2014 Waxman I et al: Endoscopic diagnosis and therapies for Barrett esophagus. A review. Rev Esp Enferm Dig. 106(2):103-19, 2014

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Esophagus

Caustic Esophagitis KEY FACTS

TERMINOLOGY • Esophageal injury due to ingestion of strong alkali or acid ○ Causes mild to severe injury to upper GI tract – Esophagus > stomach > duodenum

IMAGING • Imaging evaluation: CECT for acute injury; barium esophagram for chronic ○ If esophagram done in acute phase, use nonionic, watersoluble agent (e.g., Omnipaque) • Fluoroscopic: Esophagram ○ Stage 1: Acute severe phase (1-4 days) – Narrowed lumen with irregular contour/ulcerations – May have signs of perforation (extraluminal gas and contrast medium) ○ Stage 2: Ulcer granulation phase (5-28 days) – More defined ulcers; spasm ○ Stage 3: Cicatrization and scarring (3-4 weeks)

(Left) Graphic shows a long stricture of the esophagus and ulceration of the mucosa. The stomach is pulled up into the chest due to foreshortening of the esophagus by fibrosis &/or spasm. (Right) Spot film from a barium esophagram in a patient with chronic stricture from caustic ingestion shows a shortened and strictured esophagus, with the proximal stomach pulled into the chest. This stricture has been treated repeatedly by balloon dilation, and the patient has not required surgery.

(Left) Axial CECT of a patient 2 hours after caustic ingestion shows marked thickening of the esophageal wall and bilateral aspiration pneumonitis . (Right) Axial CECT in the same patient shows marked thickening of the gastric wall with submucosal edema , indicating corrosive gastritis.

172

– Strictures, usually long and smooth, can be irregular and eccentric – Sacculations, pseudodiverticula – Stomach is often pulled up into chest by esophageal shortening • CT Findings ○ Acute phase – Target sign: Mucosal enhancement and hypodense submucosa – Esophageal perforation: Pneumomediastinum, pleural effusion ○ Chronic phase: Luminal irregularity and narrowing – Similar findings in stomach ± duodenum

CLINICAL ISSUES • Complications: Perforation, mediastinitis, peritonitis, fistulas, shock

Caustic Esophagitis

Synonyms

Iatrogenic Injury: Feeding Tubes • Usually seen in patients with longstanding intubation • Long, smooth stricture of esophagus seen

• Corrosive esophagitis

Definitions • Esophageal injury due to ingestion of strong alkali or acid

IMAGING General Features • Best diagnostic clue ○ Long stricture ± diffuse ulceration of esophagus

Radiographic Findings • Chest PA and lateral views (acute) ○ Dilated, gas-filled esophagus ○ May show aspiration pneumonitis ○ Esophageal perforation – Pneumomediastinum, pleural effusion • Fluoroscopic: Esophagram ○ Stage 1: Acute severe phase (1-4 days) – Narrowed lumen with irregular contour/ulcerations – May have signs of perforation □ Gas, fluid, or oral contrast medium in mediastinum ± pleural space ○ Stage 2: Ulcer granulation phase (5-28 days) – More defined ulcers; spasm ○ Stage 3: Cicatrization and scarring (3-4 weeks) – Strictures, usually long and smooth, can be irregular and eccentric – Sacculations, pseudodiverticula – Stomach is often pulled up into chest by esophageal shortening

PATHOLOGY General Features • Etiology ○ Strong alkaline agents: Liquid lye (sodium hydroxide) – Most common agent in USA; used as liquid drain cleaner ○ Strong acids: Hydrochloric, sulfuric, acetic, oxalic, carbolic/nitric • Associated abnormalities ○ Associated gastroduodenal injuries seen in most on CT, fewer on esophagram and upper GI series

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pain, drooling, vomiting, hematemesis ○ Odynophagia, fever, shock • Clinical profile ○ Patient with history of caustic ingestion and painful swallowing

Demographics • Age ○ Adults: Usually intentional (suicide attempt) ○ Children: Accidental • Epidemiology ○ Most common cause of caustic esophagitis in USA: Ingestion of liquid lye drain cleaner

CT Findings

Natural History & Prognosis

• Circumferential esophageal wall thickening ( 5 mm) • Acute phase ○ Target sign: Mucosal enhancement and hypodense submucosa ○ Esophageal perforation: Pneumomediastinum, pleural effusion • Chronic phase: Luminal irregularity and narrowing • Similar findings in stomach ± duodenum

• Complications ○ Perforation, mediastinitis, peritonitis, fistulas, shock ○ Increased risk of cancer after 20-40 years • Prognosis ○ Acute mild phase with early treatment: Good ○ Acute severe and chronic phases: Poor

Imaging Recommendations • Best imaging tool ○ CECT for acute injury; barium esophagram for chronic ○ Acute phase esophagram (if needed): Water-soluble, nonionic contrast agent

DIFFERENTIAL DIAGNOSIS

Treatment • Medical ○ Steroids, antibiotics, parenteral feedings ○ Esophageal bougienage for strictures • Surgical ○ Esophageal (± gastric) bypass with jejunal or colonic interposition

DIAGNOSTIC CHECKLIST

Radiation Esophagitis

Image Interpretation Pearls

• Stricture: Usually smooth, tapered narrowing within area of radiation

• History of caustic ingestion and imaging findings are usually diagnostic

Reflux Esophagitis • Short, distal esophageal stricture ± hiatal hernia and reflux

Esophageal Carcinoma • Patients with caustic injury may develop carcinoma later

Esophagus

TERMINOLOGY

SELECTED REFERENCES 1.

Youn BJ et al: Balloon dilatation for corrosive esophageal strictures in children: radiologic and clinical outcomes. Korean J Radiol. 11(2):203-10, 2010

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Esophagus

Drug-Induced Esophagitis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Esophageal injury induced by direct contact with oral medications

• • • •

IMAGING • Ulcers and spasm occur at sites of esophageal narrowing ○ Aortic arch, left main bronchus, retrocardiac • Findings on esophagram (double contrast) ○ Solitary or localized cluster of tiny ulcers distributed circumferentially on normal background mucosa ○ Punctate, linear, stellate, serpiginous, or ovoid; collections of barium on esophageal surface ○ Longer areas of ulceration with potassium chloride, quinidine, biphosphonates, and in patients with cardiomegaly ○ Mass effect surrounding ulcer due to edema and inflammation; can mimic ulcerated carcinoma • Superficial ulceration ○ Giant, flat ulcers are uncommonly seen

(Left) Graphic shows medication pills stuck at the level of the aortic arch with focal spasm and ulceration . (Right) Esophagram shows broad, shallow ulceration at the aortic arch level. The patient had odynophagia and recent tetracycline ingestion, and the symptoms resolved spontaneously. Physiological points of esophageal narrowing, such as at the aortic arch and the retrocardiac portion of the esophagus, are the most commonly cited for pillinduced esophagitis.

(Left) Double-contrast barium esophagram in a 50-year-old woman with odynophagia while taking tetracycline shows multiple ulcerations and a subtle stricture or spasm of the distal esophagus. (Right) This 70-year-old woman with cardiac disease awoke with severe odynophagia the morning after taking her quinidine at bedtime. Barium esophagram demonstrates a long stricture or focal spasm from the thoracic inlet to the aortic arch without definite ulceration.

174

Reflux esophagitis Viral esophagitis Esophageal carcinoma Barrett esophagus

CLINICAL ISSUES • Patient wakes up with severe odynophagia in morning after taking medications at bedtime with insufficient water ○ Usually resolves spontaneously • Main classes of medications at fault ○ Antibiotics (especially tetracyclines) ○ Anti-inflammatories (aspirin , NSAIDS, etc.) ○ "Cardiac" drugs (quinidine, potassium chloride, etc.) ○ Biphosphonates (to prevent bone loss; can cause severe, longer segment esophageal ulceration)

Radiation Esophagitis

IMAGING • Videofluoroscopic esophagram ○ Start with nonionic, low osmolar, water-soluble contrast medium (e.g., Omnipaque) – Concern for aspiration and fistula ○ Follow with barium if no leak or fistula • Acute radiation esophagitis (RE) ○ Superficial ulcers; shallow, irregular collections of barium on esophageal mucosa ○ Location: Usually conforms to radiation portal ○ Disordered motility, interruption of primary peristalsis ○ May be seen within days to weeks of RT • Chronic RE ○ Strictures: Concentric, smooth, tapered narrowing ○ Upper or mid esophagus within radiation portal ○ Usually 4-8 months after completion of RT ○ Late-developing deep ulcers; ominous, raising concern for fistula, especially to bronchus

○ Motility disturbance may persist forever • CT shows radiation port indirectly ○ Scarring of lung in paramediastinal distribution ○ Thick-walled esophagus ○ Shows any residual tumor or lymphadenopathy • PET/CT ○ Caution: radiation injury to esophagus and mediastinum may be FDG avid

Esophagus

KEY FACTS

TOP DIFFERENTIAL DIAGNOSES • • • • •

Reflux esophagitis Caustic esophagitis Infectious esophagitis Nasogastric intubation esophagitis Tumor recurrence

CLINICAL ISSUES • Treatment: Viscous lidocaine, indomethacin for acute ○ Strictures: Endoscopic dilation and stent

(Left) Axial CECT in an elderly man with lung cancer who developed dysphagia and odynophagia while receiving radiation therapy to his mediastinum shows a right lung tumor and mediastinal lymphadenopathy . The esophageal wall is thickened and the lumen is narrowed. (Right) Esophagram in the same patient shows a long stricture of the mid thoracic esophagus with dilation of the proximal portion , indicating partial obstruction in this classic example of radiation esophagitis.

(Left) Axial CECT in a middleaged man with lung cancer who received radiation and chemotherapy demonstrates extensive fibrosis and volume loss of the right lung in a paramediastinal distribution, corresponding to the radiation port. (Right) Barium esophagram in the same patient demonstrates a long, tight stricture of the upper and mid esophagus, corresponding to the radiation port. The pharynx is dilated above the stricture.

175

Esophagus

Eosinophilic Gastroenteritis and Esophagitis KEY FACTS

TERMINOLOGY • Inflammatory disease of GI tract characterized by tissue eosinophilia that can involve all layers of wall ○ "Eosinophilic gastroenteritis" is a misnomer; can affect any portion of GI tract • Requires 4 criteria for diagnosis ○ Presence of GI symptoms ○ Biopsy proof of eosinophilic infiltration of 1 or more areas of GI tract ○ Absence of eosinophilic involvement of multiple organs outside GI tract ○ Absence of parasitic infestation

IMAGING • Esophageal involvement (eosinophilic esophagitis) ○ Most characteristic findings: Ringed esophagus (concentric, thin, web-like strictures) ○ May coexist with longer strictures

(Left) Films from an esophagram in a 33-year-old woman complaining of food sticking in her esophagus demonstrate several ring-like strictures of the proximal esophagus as well as more distal and longer strictures . These were persistent on multiple films. (Right) Endoscopic photograph in the same patient shows the same ring-like strictures likened to tracheal rings and considered characteristic of this disorder.

(Left) Spot film from an esophagram in a 7-year-old girl shows a shortened esophagus pulling the stomach into the chest. A mild mid esophageal stricture is also noted. The appearance is diagnostic of esophagitis, but not the specific type. (Right) Oblique esophagram in the same patient shows the hiatal hernia and stricture again.

176

○ Strictures, webs, and spasm account for symptoms of food and pill impaction within esophagus • GI involvement ○ Most common site of GI tract involvement ○ Nonspecific fold thickening ± submucosal edema ○ ± malabsorption pattern (dilution of barium, etc.)

TOP DIFFERENTIAL DIAGNOSES • Intestinal parasites and infestation • Other causes of esophagitis and stricture • Esophageal webs

PATHOLOGY • Most patients have history of food intolerance &/or multiple allergies

DIAGNOSTIC CHECKLIST • Yield of imaging is probably highest in eosinophilic esophagitis

Epidermolysis and Pemphigoid

TERMINOLOGY • Epidermolysis bullosa: Rare inherited disease that causes blistering of skin and mucous membranes • Benign mucous membrane pemphigoid: Acquired autoimmune skin-blistering disease

IMAGING • Esophageal strictures ○ Most commonly in upper 1/3 of esophagus • Esophageal webs seen early in benign mucous membrane pemphigoid; occasionally seen in epidermolysis bullosa

CLINICAL ISSUES • Both diseases are rare • Epidermolysis bullosa ○ Presents in early childhood ○ Severe skin blistering, nail dystrophy ○ Webbing between fingers and toes, can eventually lead to contractures or amputation of digits

○ Diffuse osteopenia, muscle atrophy secondary to underuse ○ Genitourinary abnormalities: Vaginal stenosis, bladder wall thickening • Benign mucous membrane pemphigoid ○ Presents in 4th decade ○ Bullae, preference for mucous membranes ○ Individual bullae may resolve or progress to ulceration or stenosis ○ Oral mucosa involved in all patients, conjunctiva in most patients • Treatment: Endoscopic dilation may be tried but it may lead to worse strictures • Colonic interposition: To bypass refractory esophageal lesions

Esophagus

KEY FACTS

(Left) Oblique esophagram in a 19-year-old man with epidermolysis bullosa shows a tight, long stricture of the proximal esophagus. The proximal end of the stricture is fairly abrupt, while the distal end is more tapered. (Right) Oblique esophagram in the same patient after attempted dilation shows that the stricture remains , now with extravasation of the contrast material , indicating perforation. The contrast material extends along the esophageal wall within the mediastinum.

(Left) Spot film from an esophagram in a 30-year-old woman with severe epidermolysis bullosa demonstrates a long stricture of the distal esophagus. Other films demonstrated more proximal strictures. These were treated with balloon dilation but have recurred. (Right) Lateral esophagram in an 18-year-old man shows a web-like stricture near the pharyngoesophageal junction that is the result of repeated episodes of mucosal ulceration, typical of patients with epidermolysis bullosa.

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Esophagus

Esophageal Webs KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Thin mucosal fold narrowing esophageal lumen ○ Lacks muscle layer (unlike distal esophageal A and B rings)

• Esophageal strictures ○ Longer length of luminal narrowing of esophagus • Schatzki ring ○ Lower (GE junction) esophageal or Β ring

IMAGING • Full column barium esophagram with rapid-sequence filming or have patient swallow small marshmallow followed by barium • Appearance: 1-2 mm wide, shelf-like filling defect ○ Usually along anterior wall of cervical esophagus ○ Circumferential, radiolucent ring in some cases ○ May occur at other sites in esophagus • Mild, moderate, or severe luminal narrowing • Partial obstruction suggested by ○ Jet phenomenon: Barium spurting through ring ○ Dilatation of esophagus or pharynx proximal to web

(Left) Rapid-sequence barium esophagram in a 45-year-old woman with dysphagia shows a thin, shelf-like indentation from the anterior and lateral walls of the pharyngoesophageal junction. (Right) Frontal esophagram in the same patient shows abnormal distension of the pharynx above this web , confirming that it is causing partial obstruction and luminal narrowing.

(Left) Barium esophagram in a 50-year-old woman with solid food dysphagia shows a shelflike narrowing of the proximal esophageal lumen. This web is unusually thick and circumferential. (Right) Lateral esophagram in a young patient with epidermolysis bullosa shows a web-like stricture near the pharyngoesophageal junction, representing a stricture due to repeated episodes of mucosal ulceration, typical of patients with epidermolysis.

178

PATHOLOGY • Esophageal webs may be associated with ○ Plummer-Vinson (Paterson-Kelly) syndrome ○ Epidermolysis, pemphigoid ○ Eosinophilic esophagitis ○ Celiac-sprue disease ○ Chronic GE reflux ○ Graft vs. host disease

CLINICAL ISSUES • Usually asymptomatic • Dysphagia with impaction of food or pills above web • Respond to balloon or bougie dilation, but often recur

Cricopharyngeal Achalasia

TERMINOLOGY

PATHOLOGY

• Failure of cricopharyngeal muscle (upper esophageal sphincter) relaxation due to hypertrophy or spasm

• Usually just "poor timing" of cricopharyngeal contraction ○ Due to "presbyesophagus" or other cause of dysmotility in most cases • May occur as an isolated abnormality

IMAGING • Prominent cricopharyngeus muscle at pharyngoesophageal junction with retention of barium in pharynx on lateral view ○ Pharyngoesophageal junction: C5-6 level • Videofluoroscopic recording: Frontal, lateral, and oblique ○ Rapid sequence filmong required for demonstration

TOP DIFFERENTIAL DIAGNOSES • Cervical osteophytes (indentation) ○ Large anterior cervical osteophytes can impinge on pharyngoesophageal junction, simulating cricopharyngeal achalasia • Esophageal tumor ○ Tumor at pharyngoesophageal junction may constrict lumen concentrically or eccentrically

Esophagus

KEY FACTS

CLINICAL ISSUES • Intermittent symptoms: Dysphagia, food "sticking" in throat (at suprasternal level) • Treat underlying problem ○ e.g., reflux esophagitis with spasm • Rarely requires cricopharyngeal myotomy or botulinim toxin injection

DIAGNOSTIC CHECKLIST • Persistent narrowing or just intermittent indentation • Smoothly outlined lip-like projection posteriorly at C5-6 level with jet effect seen via narrowed lumen

(Left) Graphic shows hypertrophied contracted cricopharyngeus muscle at the pharyngoesophageal junction (usually near the C5-6 cervical level). (Right) Lateral view from an esophagram shows a typical appearance of cricopharyngeal achalasia, with a large filling defect along the posterior wall of the pharyngoesophageal junction, at the C5-6 level. Note the distension of the pharynx proximal to this process.

(Left) Lateral film from an esophagram shows a prominent cricopharyngeal "bar" at the C5-6 level in a woman with symptoms of reflux and pills "sticking" in her throat. (Right) Spot film of the lower esophagus in the same woman shows a hiatal hernia and marked gastroesophageal reflux. Cricopharyngeal achalasia is most often seen in patients with other esophageal disorders, such as reflux esophagitis or motility disorders.

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Esophagus

Esophageal Achalasia KEY FACTS

IMAGING • Classified based on etiology: Primary or secondary • Primary (idiopathic) ○ "Bird beak" deformity: Dilated esophagus with smooth, symmetric, tapered narrowing at esophagogastric region ○ Transient flow of fluid into stomach when hydrostatic pressure of fluid column exceeds tonic LES pressure ○ Length of narrowed segment < 3.5 cm; widest diameter upstream is > 4 cm • Secondary (pseudoachalasia) ○ Intrinsic or extrinsic tumor, peptic stricture, postvagotomy, Chagas disease • Manometric characteristics of achalasia ○ Increased or normal resting lower esophageal sphincter pressures ○ Incomplete or absent LES relaxation on swallowing

TOP DIFFERENTIAL DIAGNOSES • Esophageal scleroderma

(Left) Upright frontal esophagram shows a dilated esophagus with an abrupt taper ("bird beak") just above the gastroesophageal (GE) junction . Note the absent gastric air bubble and the fluid-barium level within the esophagus. (Right) Esophagram shows a grossly dilated, tortuous esophagus with a "sigmoid" appearance. This is an example of longstanding achalasia.

(Left) Upright chest radiograph shows an absent air-fluid level in the stomach of a 28-year-old woman with a recent onset of dysphagia and halitosis. (Right) Esophagram in the same young woman shows marked dilation of the esophageal lumen ending in a smoothly tapered "bird beak" deformity .

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• Esophageal carcinoma • Esophagitis with stricture

PATHOLOGY • Complications ○ Aspiration pneumonitis ○ Superimposed infection (e.g., Candida esophagitis) ○ 10x increased risk of carcinoma

CLINICAL ISSUES • Treatment ○ Heller myotomy (partial thickness incision of lower esophageal sphincter) – Partial (Toupet) fundoplication often incorporated into myotomy procedure ○ Per-oral endoscopic myotomy (POEM) procedure – Relief of symptoms with fewer complications

Esophageal Achalasia

Definitions • Primary esophageal motility disorder due to defective neural stimulation of lower esophageal sphincter

IMAGING

○ Secondary achalasia (pseudoachalasia) – Mildly dilated esophagus (< 4 cm at its widest point) – Decreased or absent peristalsis – Eccentricity, nodularity, shouldering of narrowed distal segment – Length of distal narrowed esophageal segment: Usually > 3.5 cm

General Features

CT Findings

• Best diagnostic clue ○ "Bird beak" deformity: Dilated esophagus with smooth, symmetric, tapered narrowing at esophagogastric region • Morphology ○ Grossly dilated esophagus with smooth tapering at lower end of esophagus • Other general features ○ Classified based on etiology – Primary (idiopathic) – Secondary (pseudoachalasia) ○ Manometric characteristics of achalasia – Absence of primary peristalsis – Increased or normal resting lower esophageal sphincter (LES) pressures – Incomplete or absent LES relaxation on swallowing ○ Variants of achalasia: Atypical manometric findings – Early: Characterized by aperistalsis with normal LES pressure – Vigorous: Simultaneous high amplitude and repetitive contractions – Both variants are transitional and finally evolve into classic achalasia ○ Classic achalasia (primary): Simultaneous low amplitude contractions ○ Motor function of pharynx and upper esophageal sphincter are normal

• Moderate to marked dilatation of esophagus with diameter > 4 cm • Decreased or normal wall thickness • Air-fluid level within dilated esophagus • Abrupt, smooth narrowing of distal esophageal segment near GE junction • Squamous cell carcinoma of esophagus in longstanding achalasia ○ Irregular wall thickening ○ Eccentric narrowing of distal esophagus extending into GE junction ○ Involvement of periesophageal soft tissues and blood vessels ○ Enlarged mediastinal lymph nodes

Radiographic Findings • Radiography ○ Chest x-ray AP and lateral views – Advanced achalasia □ Mediastinal widening, double contour of mediastinal borders □ Outer borders represent dilated esophagus projecting beyond shadows of aorta and heart □ Anterior tracheal bowing – Air-fluid level in mediastinum, small or absent gastric air bubble – Lower lobes: Decreased lung volume, linear opacities, and tubular radiolucencies □ Evidence of aspiration pneumonitis • Videofluoroscopic barium study findings ○ Primary achalasia – Markedly dilated esophagus – Absent primary peristalsis – "Bird beak" deformity: V-shaped, conical, and smooth; symmetric tapered narrowing of distal esophagus extending to gastroesophageal (GE) junction – Esophagus empties when hydrostatic pressure of fluid column is above tonic LES pressure – Length of narrowed segment < 3.5 cm; widest diameter upstream > 4 cm

Esophagus

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Barium esophagography • Videofluoroscopic barium studies • Helical CT including sagittal reconstructions • Timed barium swallow studies ○ Aid in diagnosis and management of achalasia • Transit and emptying studies ○ Quantitate esophageal retention before and after therapy ○ Standing films taken after ingestion of 200 mL barium at 1, 2, and 5 minutes

DIFFERENTIAL DIAGNOSIS Esophageal Scleroderma • Uncomplicated cases: Dilated esophagus with patulous esophagogastric region • Later findings ○ Aperistalsis, dilated esophagus ○ Peptic stricture in distal 1/3 – May simulate primary achalasia

Esophageal Carcinoma • Asymmetric contour with abrupt proximal borders of narrowed distal segment ("rat tail" appearance) • Mucosal irregularity, shouldering, mass effect • Periesophageal and distal spread may be seen • Occasionally, smooth, tapered narrowing of lower esophagus with aperistalsis is present, simulating achalasia • Diagnosis: Endoscopic biopsy and history

Gastric Carcinoma • Malignancy involving gastric cardia with extension into distal esophagus ○ Smooth or irregular tapered narrowing of lower esophagus with aperistalsis, simulating achalasia • Look for mass within fundus of stomach 181

Esophagus

Esophageal Achalasia

• Diagnosis: Endoscopic biopsy

Demographics

Esophagitis With Stricture • Peptic stricture: Smooth, tapered narrowing of short distal segment ○ Almost always associated with hiatal hernia and GE reflux ○ Rarely associated with aperistalsis or gross dilatation • Diagnosis: Endoscopic biopsy and history

• Age ○ Primary achalasia: Younger patients (30-50 years old) – Prevalence: 1 in 10,000 ○ Secondary achalasia: Older patients • Gender ○ M=F

Neuromuscular Disorders

Natural History & Prognosis

• Diffuse esophageal spasm (DES) ○ Characterized by chest pain, radiation to shoulder simulating angina, and dysphagia ○ Sometimes contractions are repetitive and esophageal lumen may show typical "corkscrew" or "rosary bead" appearance ○ Mostly normal LES function with complete sphincter relaxation during swallowing ○ Diagnosis: Clinical, radiographic, and manometric

• Complications ○ Coughing, aspiration, pneumonia, lung abscess ○ Esophageal carcinoma (in 0.1-7% of cases) • Prognosis ○ Treatment cannot correct abnormal esophageal motility and LES dysfunction ○ Aimed at improving esophageal emptying by disrupting increased LES pressure

Postoperative State, Esophagus

• Temporary palliation ○ Calcium channel blockers, botulinum toxin injection ○ Pneumatic dilatation (effects last 5-10 years) • Heller myotomy (partial thickness incision of LES) ○ Coupled with "partial" fundoplication (e.g., 270° Toupet) • Per-oral endoscopic myotomy (PEM) ○ "Incisionless"; relieves LES pressure and dysphagia symptoms with low complication risk • Risks of treatment ○ Pneumatic dilatation: Perforation ○ Myotomy: Perforation and reflux – Partial (Toupet) fundoplication often incorporated into myotomy procedure

• Stricture and neural damage may simulate achalasia • Vagotomy reduces peristalsis

PATHOLOGY General Features • Etiology ○ Pathogenesis of primary achalasia – Idiopathic; abnormality of myenteric ganglia (decrease in number) in Auerbach plexus – Degenerative vagal nerve changes ○ Secondary achalasia: Intrinsic/extrinsic neoplasm, peptic stricture, scleroderma, Chagas disease, post-vagotomy effect • Associated abnormalities ○ Marked esophageal wall thinning + risk of rupture ○ Following mucosal changes may be seen – Ulceroinflammatory lesions with white thickened patches (leukoplakia) – Superimposed infection (e.g., Candida esophagitis) – Sites of dysplasia or neoplasia □ 10x increased risk of carcinoma

Treatment

DIAGNOSTIC CHECKLIST Consider • Seek evidence of cancer, prior surgery, severe gastroesophageal reflux disease

SELECTED REFERENCES 1.

Gross Pathologic & Surgical Features

2.

• Massively dilated esophagus with smooth, narrowed distal segment

3.

Microscopic Features • Decreased number of ganglion cells in myenteric plexus of esophagus

4. 5.

6.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Primary achalasia – Longstanding dysphagia, weight loss – Regurgitation, foul breath (90% of patients) – Aspiration pneumonitis ○ Secondary achalasia – Short duration of dysphagia – Chest pain or odynophagia 182

7.

8.

Teitelbaum EN et al: Symptomatic and physiologic outcomes one year after peroral esophageal myotomy (POEM) for treatment of achalasia. Surg Endosc. ePub, 2014 Richter JE: Update on the management of achalasia: balloons, surgery and drugs. Expert Rev Gastroenterol Hepatol. 2(3):435-45, 2008 Williams VA et al: Achalasia of the esophagus: a surgical disease. J Am Coll Surg. 208(1):151-62, 2009 Sabharwal T et al: Balloon dilation for achalasia of the cardia: experience in 76 patients. Radiology. 224(3):719-24, 2002 Vaezi MF et al: Timed barium oesophagram: better predictor of long term success after pneumatic dilation in achalasia than symptom assessment. Gut. 50(6):765-70, 2002 Adler DG et al: Primary esophageal motility disorders. Mayo Clin Proc. 76(2):195-200, 2001 Woodfield CA et al: Diagnosis of primary versus secondary achalasia: reassessment of clinical and radiographic criteria. AJR Am J Roentgenol. 175(3):727-31, 2000 de Oliveira JM et al: Timed barium swallow: a simple technique for evaluating esophageal emptying in patients with achalasia. AJR Am J Roentgenol. 169(2):473-9, 1997

Esophageal Achalasia Esophagus

(Left) Esophagram shows a typical appearance of achalasia, pre-Heller myotomy, with "bird beak" deformity of the distal esophagus , marked dilation of the proximal esophageal lumen, and absent peristalsis. (Right) Esophagram in the same patient following Heller myotomy shows that the esophageal lumen is no longer dilated. The esophagus emptied readily in the upright position, due to gravity, while peristalsis was still absent.

(Left) Esophagram shows typical findings of achalasia plus numerous irregular plaques due to Candida esophagitis. (Right) Upright barium esophagram shows retained food and fluid within the dilated esophagus of a 78-year-old woman with dysphagia. Deep, nonpropulsive tertiary contractions are noted. This is an example of vigorous achalasia, in which esophageal contractions are seen but are not effective. Manometry confirmed achalasia.

(Left) Esophagram in a patient with longstanding achalasia shows an irregular constricting, "apple core" mass , which proved to be squamous cell carcinoma. (Right) Esophagram shows a dilated esophagus with tertiary contractions simulating achalasia. The abrupt narrowing of the lumen with overhanging edges and presence of nodular thickened folds suggests the true diagnosis of gastric carcinoma, causing this pseudoachalasia appearance.

183

Esophagus

Esophageal Motility Disturbances KEY FACTS

IMAGING • Primary: Achalasia, diffuse esophageal spasm, presbyesophagus • Secondary: Scleroderma, various causes of esophagitis • Achalasia: Idiopathic or neurogenic disorder ○ Markedly dilated esophagus; absent primary peristalsis ○ "Bird's beak" deformity in esophagogastric region • Diffuse esophageal spasm (DES) ○ Contractions are repetitive, esophageal lumen may show "corkscrew" or "rosary bead" pattern ○ Often with chest pain during contractions • Presbyesophagus or nonspecific esophageal motility disorder: Multiple aperistaltic (tertiary) contractions and primary peristalsis ○ Extremely common • Scleroderma ○ Patulous gastroesophageal region and reflux fusiform distal peptic stricture ± hiatal hernia

(Left) Barium esophagram in an elderly man with dysphagia and heartburn demonstrates a small hiatal hernia and a stricture at the gastroesophageal junction . Tertiary contractions are also noted . (Right) Esophagram in the same patient shows free GE reflux noted on rolling the patient into a supine position. The esophageal dysmotility in this patient is probably a result of age as well as the effects of reflux esophagitis on motility.

(Left) Spot film from an esophagram in an elderly man with diffuse esophageal spasm shows intermittent obliterative contractions, imparting a "corkscrew" appearance to the esophagus. (Right) Spot films from an esophagram in an elderly woman with esophageal spasm show obliterative, deep contractions. Multiple bariumfilled pulsion diverticula are evident , especially after the barium bolus has passed. Pulsion diverticula are closely associated with esophageal dysmotility.

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○ Absence of peristalsis in lower 2/3 of esophagus

TOP DIFFERENTIAL DIAGNOSES • Reflux esophagitis ○ Esophagitis may impair peristalsis • Fundoplication complications (especially in elderly) • Esophageal (or gastric fundus) carcinoma • Postoperative state, esophagus ○ Vagotomy may impair peristalsis ○ Esophagectomy with gastric conduit

DIAGNOSTIC CHECKLIST • Correlate: Clinical, radiographic, and manometric findings • Fluoroscopic diagnosis requires imaging in prone or supine position, not upright • Patients with esophageal dysmotility often complain of food sticking in cervical esophagus • Intermittent cricopharyngeal spasm identified, but not primary dysfunction

Esophageal Motility Disturbances

Definitions • Primary and secondary motility disorders of esophageal smooth muscle

IMAGING General Features • Best diagnostic clue ○ Achalasia: "Bird's beak" deformity (dilated esophagus with smooth, tapered narrowing at GE junction) ○ Scleroderma: Dilated, atonic esophagus with distal stricture (late finding) ○ Presbyesophagus: Weak primary peristalsis ± intermittent tertiary contractions • Other general features ○ Classification of esophageal motility disorders – Primary: Achalasia, diffuse esophageal spasm, presbyesophagus – Secondary: Scleroderma, various causes of esophagitis ○ Achalasia: Idiopathic or neurogenic disorder – Absence of primary peristalsis – Simultaneous low-amplitude contractions □ May have prominent tertiary contractions (vigorous achalasia) – Increased or normal resting lower esophageal sphincter (LES) pressures – Incomplete or absent LES relaxation on swallowing – Normal upper esophageal sphincter ○ Diffuse esophageal spasm (DES): Related to varying degrees of neurogenic damage – Simultaneous contractions and intermittent primary peristalsis – Repetitive or prolonged-duration contractions – High amplitude and frequent spontaneous contractions – Normal LES function with complete sphincter relaxation during swallowing – Intermittent disruption of primary peristalsis associated with focal obliterative contractions ○ Presbyesophagus: Esophageal motility dysfunction associated with aging – Also called nonspecific esophageal motility disorder (NEMD) – Decreased frequency of normal peristalsis – Increased frequency of aperistaltic contractions – Less commonly, incomplete LES relaxation ○ Scleroderma: Multisystemic disorder of small vessels and connective tissue – Decreased or absent resting LES pressure – Absent peristalsis in lower 2/3 of esophagus ○ Other esophagitises: Reflux, infectious, caustic – Irritated esophageal mucosa often results in abnormal peristalsis – Can become feedback loop with more stasis of irritant more injury more dysmotility

Fluoroscopic Findings • Videofluoroscopic barium studies ○ Achalasia

– Markedly dilated esophagus – Absent primary peristalsis – "Bird's beak" deformity: V-shaped conical and smooth, tapered narrowing at esophagogastric region ○ DES – Primary peristalsis present in cervical esophagus – Intermittent absence of primary peristalsis in thoracic esophagus and focally obliterative contractions – Contractions are repetitive; esophageal lumen may show "corkscrew" or "rosary bead" pattern □ Often with chest pain during contractions ○ Presbyesophagus or NEMD: Multiple aperistaltic (tertiary) contractions and primary peristalsis ○ Scleroderma – Patulous GE region and reflux fusiform distal peptic stricture ± hiatal hernia – Absence of peristalsis in lower 2/3 of esophagus – Late: Mild to moderate dilatation of proximal esophagus □ ± wide-mouthed sacculations of esophagus (rare) – Scleroderma: 70% have GE reflux 37% develop Barrett esophagus

Esophagus

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Reflux Esophagitis • Ulcers: Multiple tiny ulcers with thickened folds • Peptic stricture: Smooth narrowing of distal segment ○ Associated with hiatal hernia and GE reflux ○ Esophagitis may impair peristalsis ○ Usually less esophageal dilation than with achalasia

Fundoplication Complications • Dilated esophagus, narrowed GE junction, and delayed esophageal emptying • Fairly common result or complication of fundoplication, especially in elderly ○ Elderly commonly have weak primary peristalsis

Esophageal (or Gastric Fundal) Carcinoma • Asymmetric contour with abrupt proximal borders of narrowed distal segment ("rat tail" appearance) • Mucosal irregularity, shouldering, mass effect • Smooth, tapered narrowing of lower esophagus with aperistalsis simulates achalasia or scleroderma • Gastric cancer invading esophagus submucosa may closely mimic achalasia • Diagnosis: Endoscopic biopsy and history

Postoperative State, Esophagus • Vagotomy may impair peristalsis • Esophagectomy with gastric conduit ○ Redundant conduit can closely resemble dilated, aperistaltic esophagus (achalasia)

PATHOLOGY General Features • Etiology ○ Achalasia: Idiopathic or neurogenic disorder – Abnormality of myenteric ganglia in Auerbach plexus; degenerative vagal nerve changes 185

Esophagus

Esophageal Motility Disturbances ○ Diffuse esophageal spasm – Unknown – Related to varying degrees of neurogenic damage ○ Presbyesophagus: Due to aging ○ Scleroderma – Unknown; autoimmune and genetic predisposition – Environmental antigens: Silica, L-tryptophan • Genetics ○ Scleroderma – Localized: Associated with HLA-DR1, 4, and 5 – Diffuse: Associated with HLA-DR5 • Associated abnormalities ○ Scleroderma may be associated with lupus, polymyositis, or dermatomyositis ○ Achalasia – May have superimposed infection (e.g., Candida) – Increased risk of carcinoma ○ Scleroderma – Other organ system involvement, such as lung and bowel

Gross Pathologic & Surgical Features • Achalasia: Massively dilated esophagus with smooth, narrowed distal segment • DES: Esophageal muscle is normal or hypertrophied • Scleroderma ○ Rubber hose inflexibility: Lower 2/3 esophagus ○ Thin and ulcerated mucosa + distal stricture

Natural History & Prognosis • Complications ○ Coughing, aspiration, pneumonia, lung abscess ○ Scleroderma and achalasia: Barrett esophagus, adenocarcinoma • Prognosis ○ Achalasia: Fair by improving esophageal emptying with balloon dilatation or myotomy ○ Scleroderma: Limited disease (good); diffuse (poor)

Treatment • Achalasia: Calcium channel blockers; botulinum toxin injection, pneumatic dilatation; Heller or peroral endoscopic myotomy • Scleroderma: Elevation of head end of bed, proton-pump inhibitors, metoclopramide

DIAGNOSTIC CHECKLIST Consider • Correlation between clinical, radiographic, and manometric findings

Microscopic Features

Image Interpretation Pearls

• Achalasia: number of ganglia in myenteric plexus • DES: Cellular hypertrophy of esophageal muscle • Scleroderma: Atrophy and fragmentation of smooth muscle collagen deposition + fibrosis

• Achalasia: Dilated esophagus, absence of primary peristalsis and "bird's beak" deformity of distal esophagus • Scleroderma: Mild to moderate dilatation of esophagus with distal fusiform stricture and or absent peristalsis • DES: Disrupted primary peristalsis; "corkscrew" or "rosary bead" pattern of esophagus • Presbyesophagus: Decreased primary peristalsis, shallow tertiary contractions in elderly person • Patients with esophageal dysmotility often complain of food sticking in cervical esophagus ○ Intermittent cricopharyngeal spasm identified, but not primary dysfunction

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Longstanding dysphagia for solids or liquids ○ Epigastric fullness, regurgitation, foul breath ○ Sensation of food sticking in chest; weight loss ○ Diffuse esophageal spasm – Chest pain ± radiation to shoulder or back, simulating angina – Acute odynophagia due to food impaction • Diagnosis ○ Correlate clinical, radiographic, and manometric findings ○ Endoscopic biopsy and histology

Demographics • Age ○ Achalasia and scleroderma: Young patients ○ Presbyesophagus: Elderly • Gender ○ Primary motility disorders: M = F ○ Scleroderma – Predominately women (M:F = 1:3) • Ethnicity ○ Scleroderma: African Americans > Caucasians • Epidemiology 186

○ Primary motility disorders – Achalasia and DES (uncommon) – Presbyesophagus (extremely common) ○ Secondary motility disorder (scleroderma) – Incidence: 14.1 in 1 million – Prevalence: 19-75 in 100,000

SELECTED REFERENCES 1.

2.

3. 4.

5. 6.

Côté-Daigneault J et al: High prevalence of esophageal dysmotility in asymptomatic obese patients. Can J Gastroenterol Hepatol. 28(6):311-4, 2014 Kahrilas PJ: Esophageal motor disorders in terms of high-resolution esophageal pressure topography: what has changed? Am J Gastroenterol. 105(5):981-7, 2010 Lahcene M et al: Esophageal dysmotility in scleroderma: A prospective study of 183 cases. Gastroenterol Clin Biol. 33(6-7):466-9, 2009 Morganstern B et al: GERD and Barrett's esophagus: diagnostic and management strategies in the geriatric population. Geriatrics. 64(7):9-12, 2009 Adler DG et al: Primary esophageal motility disorders. Mayo Clin Proc. 76(2):195-200, 2001 Woodfield CA et al: Diagnosis of primary versus secondary achalasia: reassessment of clinical and radiographic criteria. AJR Am J Roentgenol. 175(3):727-31, 2000

Esophageal Motility Disturbances Esophagus

(Left) Spot film from an esophagram in a middle-aged man with presbyesophagus shows a small hiatal hernia with the gastroesophagealesophageal junction marked by a Schatzki ring . (Right) Esophagram in the same patient shows intermittently evident nonpropulsive tertiary contractions .The Schatzki ring and dysmotility resulted in obstructed passage of a barium pill (not shown).

(Left) Upright esophagram in a 28-year-old woman with primary achalasia shows marked dilation of the esophageal lumen, ending in a smoothly tapered "bird's beak" deformity . (Right) Esophagram in the same patient shows absent primary peristalsis and only weak intermittent tertiary contractions, causing the undulating surface contour. Retained fluid within the esophagus dilutes the barium.

(Left) Spot film from an esophagram in a 38-year-old woman with scleroderma shows a stricture at the GE junction and dilation of the aperistaltic esophagus, with an air-fluid level indicating stasis. (Right) The same patient also had scleroderma affecting the intestine, with a dilated, aperistaltic duodenum and gastric outlet obstruction noted.

187

Esophagus

Esophageal Scleroderma KEY FACTS

TERMINOLOGY • Multisystem disorder of small vessels and connective tissue of unknown etiology

IMAGING • Atrophy, fibrosis, sclerosis of skin, vessels, and organs ○ GI tract, lungs, heart, kidneys, and nervous system • GI: 3rd most common manifestation after skin changes and Raynaud phenomenon ○ Seen in up to 90% of patients ○ Most common sites – Esophagus > duodenum > anorectal > small bowel > colon • Interstitial pulmonary fibrosis, often severe • Scleroderma is classified into 2 types ○ Diffuse scleroderma and CREST syndrome • Diffuse scleroderma ○ Cutaneous and visceral involvement – Often severe

(Left) Upright film from an esophagram in a 29-year-old woman with dysphagia and shortness of breath shows a dilated, atonic esophagus with a distal esophageal stricture . Esophageal peristalsis was completely absent. (Right) Chest CT in the same patient shows interstitial fibrosis and a massive dilated esophagus , all findings due to scleroderma.

(Left) Film from an esophagram in a young woman with dysphagia shows a dilated esophagus with a persistent air-fluid level, indicating delayed emptying. There is stricture of the distal esophagus . (Right) Subsequent film in the same patient shows a dilated duodenum with functional narrowing of its 3rd portion. The duodenum is often dilated and atonic in patients with scleroderma.

188

• CREST syndrome: Minimal cutaneous and late visceral ○ C: Calcinosis of skin ○ R: Raynaud phenomenon ○ E: Esophageal dysmotility ○ S: Sclerodactyly (involvement of fingers) ○ T: Telangiectasia • Esophagography ○ Atony or aperistalsis: Lower 2/3 (smooth muscle) ○ Mild to moderate dilatation of esophagus ○ Patulous lower esophageal sphincter (early) ○ Ulcers, fusiform peptic stricture (later) ○ Gastroesophageal reflux (70% of patients) ○ 40% develop Barrett esophagus

TOP DIFFERENTIAL DIAGNOSES • • • •

Esophageal achalasia Reflux esophagitis (with stricture) Esophageal carcinoma Iatrogenic

Esophageal Scleroderma

Synonyms • Progressive systemic sclerosis

Definitions • Multisystem disorder of small vessels and connective tissue (collagen vascular disease) of unknown etiology

IMAGING General Features • Best diagnostic clue ○ Dilated atonic esophagus with distal stricture (late findings) • Other general features ○ Multisystemic disorder with immunologic and inflammatory changes ○ Characterized by atrophy, fibrosis, and sclerosis of skin, vessels, and organs ○ Involves skin, synovium, and parenchyma of multiple organs – Gastrointestinal tract, lungs, heart, kidneys, and nervous system ○ Gastrointestinal (GI) tract scleroderma – 3rd most common manifestation after skin changes and Raynaud phenomenon – Seen in up to 90% of patients – Most common sites: Esophagus > duodenum > anus/rectum > small bowel > colon – Most frequent cause of chronic intestinal pseudoobstruction ○ Scleroderma is classified into 2 types – Diffuse scleroderma – CREST syndrome (more benign course) ○ Diffuse scleroderma: Cutaneous and visceral involvement – Interstitial pulmonary fibrosis, often severe – Organ failure more likely – Associated with antitopoisomerase 1 antibody (antiScl 70) ○ CREST syndrome: Minimal cutaneous and late visceral involvement – C: Calcinosis of skin – R: Raynaud phenomenon – E: Esophageal dysmotility – S: Sclerodactyly (involvement of fingers) – T: Telangiectasia – Associated with anticentromere antibodies

Radiographic Findings • Fluoroscopic-guided esophagography ○ Normal peristalsis above aortic arch (striated muscle) ○ Atony or aperistalsis: Lower 2/3 (smooth muscle) ○ Mild to moderate dilatation of esophagus ○ Patulous lower esophageal sphincter (LES) – Early finding of scleroderma ○ Erosions, superficial ulcers, fusiform peptic stricture – Due to reflux esophagitis ○ Gastroesophageal reflux (70% cases) – 40% develop Barrett esophagus

○ Hiatal hernia • Upper GI series ○ Stomach: Gastric dilation and delayed emptying • Small bowel follow-through ○ Duodenal dilation – Often mimics SMA syndrome – Abrupt transition to nondilated duodenum after crossing over spine in midline ○ Pathognomonic: Hidebound sign – Dilated jejunum with crowded, thin, circular folds – Seen in > 60% cases of scleroderma-related pseudoobstruction – Due to muscle atrophy and its uneven replacement by collagen in longitudinal fibers + intense fibrosis of submucosa ○ Wide-mouthed sacculations (true diverticula) on antimesenteric border ○ Prolonged transit time with barium retention in duodenum and small bowel up to 24 hours ○ ± pneumatosis intestinalis ± pneumoperitoneum – Can be due to steroid medication plus dilated bowel lumen ○ ± transient, nonobstructive intussusceptions • Barium enema ○ Sacculations on antimesenteric border of colon ○ Marked dilatation (simulates Hirschsprung disease) ○ Chronic phase: Complete loss of haustrations – Simulates cathartic colon or chronic ulcerative colitis ○ Stercoral ulceration (from retained fecal material)

Esophagus

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Esophageal Achalasia • Grossly dilated esophagus with smooth, beak-like tapering at lower end • Scleroderma shows moderate dilatation of esophagus with fusiform stricture

Reflux Esophagitis (With Stricture) • Longer tapered distal stricture • Less luminal dilation • Distinguished from scleroderma by normal peristalsis

Esophageal Carcinoma • Abrupt proximal borders of strictured segment ("rat tail" appearance) • Mucosal irregularity, shouldering, mass effect

Iatrogenic • e.g., fundoplication and vagotomy ○ Tight wrap narrows esophageal lumen ○ Vagotomy, scarring decrease peristalsis

PATHOLOGY General Features • Etiology ○ Unknown; autoimmune condition with genetic predisposition ○ May be initiated by environmental antigens like silica and L-tryptophan ○ Immunologic mechanism (delayed hypersensitivity) 189

Esophagus

Esophageal Scleroderma

– Increased production of cytokines (TNF- or IL-1) collagen production – Vascular damage and activation of fibroblasts • Genetics ○ Localized: Anticentromere antibodies associated with HLA-DR1, HLA-DR4, and HLA-DR5 ○ Diffuse: Antitopoisomerase 1 antibodies (anti-Scl 70) associated with HLA-DR5 • Associated abnormalities ○ Systemic lupus, polymyositis, or dermatomyositis

Gross Pathologic & Surgical Features • Rubber-hose inflexibility: Lower 2/3 of esophagus • Thin and ulcerated mucosa • Dilated gas and fluid-containing small bowel loops with sacculations

Small, frequent meals; elevation of head of bed Avoid tea and coffee Cimetidine, ranitidine, omeprazole Metoclopramide, laxatives Patients with severe malabsorption ○ Parenteral hyperalimentation

DIAGNOSTIC CHECKLIST Consider • Rule out other pathologies that cause distal esophageal stricture ± dysmotility • Check for family history of collagen vascular diseases

Image Interpretation Pearls

SELECTED REFERENCES collagen

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Esophagus – Dysphagia, regurgitation – Epigastric fullness and burning pain ○ Small bowel – Bloating, abdominal pain – Weight loss, diarrhea, anemia ○ Colon – Chronic constipation • Lab data ○ Increased erythrocyte sedimentation rate (ESR) ○ Iron, B12, and folic acid deficiency anemias ○ Increased antinuclear antibodies (ANA) ○ CREST syndrome: Anticentromere antibodies ○ Diffuse scleroderma – Antitopoisomerase 1 antibody

Demographics • Age ○ Onset usually by 30-50 years • Gender ○ M:F = 1:3 • Ethnicity ○ African American > Caucasian • Epidemiology ○ Incidence: ~ 20 cases per million adults in USA ○ Prevalence: 200 per million adults

Natural History & Prognosis • Complications ○ Barrett esophagus adenocarcinoma ○ Bowel pseudo-obstruction • Prognosis ○ Limited disease with ANA bodies: Good prognosis ○ Diffuse disease: Poor with involvement of kidneys, heart, and lungs rather than GI tract 190

• • • • •

• Mild to moderate dilatation of esophagus with distal fusiform stricture + decreased or absent peristalsis

Microscopic Features • Perivascular lymphocytic infiltrates • Early capillary and arteriolar injury • Atrophy and fragmentation of smooth muscle deposition and fibrosis

Treatment

1.

2.

3. 4.

5. 6.

7. 8. 9.

10. 11.

12. 13. 14. 15.

Simeón-Aznar CP et al: Systemic sclerosis sine scleroderma and limited cutaneous systemic sclerosis: similarities and differences. Clin Exp Rheumatol. ePub, 2014 Savarino E et al: Gastroesophageal reflux and pulmonary fibrosis in scleroderma: a study using pH-impedance monitoring. Am J Respir Crit Care Med. 179(5):408-13, 2009 Hinchcliff M et al: Systemic sclerosis/scleroderma: a treatable multisystem disease. Am Fam Physician. 78(8):961-8, 2008 Vonk MC et al: Oesophageal dilatation on high-resolution computed tomography scan of the lungs as a sign of scleroderma. Ann Rheum Dis. 67(9):1317-21, 2008 Sifrim D et al: Non-achalasic motor disorders of the oesophagus. Best Pract Res Clin Gastroenterol. 21(4):575-93, 2007 Ntoumazios SK et al: Esophageal involvement in scleroderma: gastroesophageal reflux, the common problem. Semin Arthritis Rheum. 36(3):173-81, 2006 Mayes MD: Scleroderma epidemiology. Rheum Dis Clin North Am. 29(2):23954, 2003 Goldblatt F et al: Antibody-mediated gastrointestinal dysmotility in scleroderma. Gastroenterology. 123(4):1144-50, 2002 Coggins CA et al: Wide-mouthed sacculations in the esophagus: a radiographic finding in scleroderma. AJR Am J Roentgenol. 176(4):953-4, 2001 Duchini A et al: Gastrointestinal hemorrhage in patients with systemic sclerosis and CREST syndrome. Am J Gastroenterol. 93(9):1453-6, 1998 Weston S et al: Clinical and upper gastrointestinal motility features in systemic sclerosis and related disorders. Am J Gastroenterol. 93(7):1085-9, 1998 Lock G et al: Gastrointestinal manifestations of progressive systemic sclerosis. Am J Gastroenterol. 92(5):763-71, 1997 Young MA et al: Gastrointestinal manifestations of scleroderma. Rheum Dis Clin North Am. 22(4):797-823, 1996 Kahan A et al: Gastrointestinal involvement in systemic sclerosis. Clin Dermatol. 12(2):259-65, 1994 Ott DJ: Esophageal motility disorders. Semin Roentgenol. 29(4):321-31, 1994

Esophageal Scleroderma Esophagus

(Left) Film from an esophagram in a 50-year-old man shows absence of primary peristalsis, with repetitive and deep tertiary contractions . The esophageal lumen is mildly dilated, and there is a stricture at the GE junction . (Right) Film obtained 2 hours after the esophagram in the same patient shows markedly delayed passage of the barium through the small bowel. The folds within the jejunum are thin and closely spaced , and the lumen is dilated with minimal peristalsis in this classic "hidebound" bowel.

(Left) A single film from a barium esophagram in a middle-aged woman with scleroderma shows a dilated, atonic esophagus with a tight stricture at the GE junction. The esophagus was slow to empty, even in the upright position, with a fluid-barium level seen . (Right) A subsequent film in the same patient shows a markedly dilated 2nd part of the duodenum , with abrupt narrowing as it crosses the spine. The duodenum is the most frequently affected part of the GI tract beyond the esophagus.

(Left) Film from an upper GI series shows reflux into the esophagus through a patulous GE junction . The esophagus had no primary peristalsis. These are relatively early signs of scleroderma, and no stricture or ulcerations have yet developed. (Right) Supine film from an upper GI series in the same patient shows reflux of barium into the dilated esophagus .

191

Esophagus

Schatzki Ring KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Annular, inflammatory, symptomatic narrowing of normal lower esophageal mucosal or B ring

• • • •

IMAGING • Most likely results from reflux or eosinophilic esophagitis • Classification based on ring diameter ○ Ring < 13 mm in diameter: Symptomatic ○ Ring 13-20 mm: Occasionally symptomatic ○ Ring > 20 mm in diameter: Asymptomatic • Single-contrast barium esophagram ○ Thin (2-4 mm in height), web-like constriction at gastroesophageal junction ○ Margins: Smooth and symmetric ○ Sliding hiatal hernia seen below ring • Schatzki ring best visualized ○ In prone right anterior oblique position ○ During suspended deep inspiration and Valsalva ○ With lumen distended with barium

(Left) Graphic shows a small hiatal hernia and an annular ring-like narrowing at the gastroesophageal (GE) junction. (Right) Film from a barium esophagram demonstrates a small hiatal hernia and a Schatzki ring with a luminal diameter of only 5-7 mm. Symptomatic narrowing of the B ring, which constitutes the Schatzki ring, probably results from reflux esophagitis.

(Left) In this young man with abrupt onset of chest pain after swallowing a piece of meat, a spot film from an esophagram shows a Schatzki ring with the piece of meat impacted above it. (Right) Initial views of the esophagus (not shown) were normal. Repeat films, taken during deep inspiration and Valsalva maneuver, show the Schatzki ring at the GE junction. This lesion can be missed if it is tilted relative to the plane of imaging or if the esophagus is not optimally distended.

192

Reflux esophagitis Esophageal webs Esophageal carcinoma Muscular or contractile or A ring

CLINICAL ISSUES • "Cheap steakhouse" syndrome: Due to inadequately chewed piece of meat impacted above ring • Recurrent dysphagia; intermittent obstruction by food ○ Treatment: Mechanical disruption by bougienage or pneumatic dilation

DIAGNOSTIC CHECKLIST • Need deep inspiration, Valsalva, distention to demonstrate Schatzki ring • Give a 13 mm barium pill to judge diameter of ring

Schatzki Ring

Definitions • Annular, inflammatory, symptomatic narrowing of normal lower esophageal mucosal or B ring

IMAGING General Features • Best diagnostic clue ○ Thin, web-like, or annular constriction at gastroesophageal (GE) junction • Other general features ○ Most likely results from reflux esophagitis – Has also been linked to eosinophilic esophagitis ○ Normal lower esophageal mucosal or B ring – Thin, waist-like indentation that marks GE junction ○ Classification based on ring diameter – Ring < 13 mm in diameter: Symptomatic – Ring 13-20 mm: Occasionally symptomatic □ e.g., with swallowing large piece of meat or pill – Ring > 20 mm in diameter: Asymptomatic

Radiographic Findings • Single-contrast barium esophagram ○ Thin (2-4 mm in height), web-like constriction at GE junction – Sliding hiatal hernia: Seen below ring ○ Margins: Smooth and symmetric ○ Fixed, anatomic, nondistensible, transverse ring with constant shape • Schatzki ring best visualized ○ When lumen above and below ring is distended beyond caliber of ring ○ With adequate distention of GE junction ○ In prone right anterior oblique position – During suspended deep inspiration and Valsalva – With lumen distended with barium ○ 50% of rings seen on prone single-contrast are not visualized on double-contrast or upright films

Imaging Recommendations • Position: Prone, right anterior oblique ○ Must distend esophagus with continuous swallows ○ Later give 13 mm diameter barium pill to swallow – Persistent obstruction to passage: Ring diameter of < 13 mm – Momentary obstruction: Diameter of 13-20 mm – No obstruction to passage: Diameter of > 20 mm

DIFFERENTIAL DIAGNOSIS Reflux Esophagitis • Irregular, asymmetric stricture; longer than Schatzki ring

Esophageal Webs • Located some distance above GE junction

Esophageal Carcinoma • Asymmetric, irregular borders within narrowed part • Longer stricture

Muscular or Contractile or A Ring • Located at superior border of esophageal vestibule • Caused by active muscular contraction • Broad, smooth area of narrowing

Esophagus

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ GE reflux disease (GERD), reflux esophagitis ○ Exaggeration of lower esophageal mucosal B ring by inflamed mucosa ± fibrosis • Associated abnormalities ○ GERD, hiatal hernia

Microscopic Features • Squamous epithelium superiorly and columnar inferiorly • Often has smooth muscle core, unlike other esophageal webs

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Symptoms relate to diameter of opening through ring ○ "Cheap steakhouse" syndrome: Due to inadequately chewed piece of meat impacted above ring – Severe chest pain, sticking sensation

Demographics • Age: More common in old age than young age • Gender: M > F • Epidemiology ○ Prevalence: 6-14% of population

Natural History & Prognosis • Complications ○ Peptic stricture with longstanding reflex ○ Perforation due to bolus obstruction, endoscopic removal and dilatation • Prognosis ○ Decrease in caliber over 5 years (in 25-33%)

Treatment • Advise to eat more slowly and chew food more carefully • Recurrent dysphagia: Mechanical disruption of ring by ○ Endoscopic rupture, bougienage, pneumatic dilation ○ Electrocautery incision, rarely surgery

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Need deep inspiration, Valsalva, distention to demonstrate Schatzki ring • Thin, nonobstructing web at GE junction should be regarded as usual B ring, not Schatzki ring

SELECTED REFERENCES 1.

Müller M et al: Endoscopic findings in patients with Schatzki rings: evidence for an association with eosinophilic esophagitis. World J Gastroenterol. 18(47):6960-6, 2012

193

Esophagus

Hiatal Hernia KEY FACTS

IMAGING • 2 general types ○ Sliding (axial) hiatal hernia (HH): Gastroesophageal (GE) junction and gastric cardia pass through esophageal hiatus ○ Paraesophageal (rolling) hernia: Gastric fundus ± other parts of stomach herniate into chest • Surgical classification ○ Type I: Sliding HH (only cardia in chest); most common type ○ Type II Paraesophageal (PEH): GE junction in normal position under diaphragm, fundus in chest (very rare) ○ Type III PEH: GE junction in chest, along with fundus ± other portions of stomach (2nd most common HH) ○ Type IV PEH: Intrathoracic stomach ± volvulus • Type I (sliding HH): Signs on upper GI series ○ Lower esophageal mucosal (B) ring observed 2 cm above diaphragmatic hiatus ○ Often reducible in erect position

(Left) Graphic outlines the surgical classification of hiatal hernias (HH). Type I is a sliding HH, and types II-IV are paraesophageal hernias. Type III is the 2nd most common type, but it is rare compared to type I (sliding HH). (Right) Esophagram in a patient with type I sliding HH shows the lower esophageal sphincter, or phrenic ampulla, marked by the A ring proximally and the B ring distally. Just below the B ring is the herniated portion of the gastric cardia .

(Left) Film from a barium esophagram in a patient with type I sliding HH shows the gastroesophageal (GE) junction, marked by the B ring . Gastric folds extend up through the hiatus. (Right) Esophagram in the same patient (supine position) reveals reflux . While reflux is commonly seen in patients with sliding HHs, it is uncertain whether the HH causes the reflux or vice versa.

194

○ Numerous (> 6) longitudinal gastric folds within HH continue through hiatus into abdominal part of stomach ○ Gastric folds converging superiorly toward a point several centimeters above diaphragm

TOP DIFFERENTIAL DIAGNOSES • Phrenic ampulla • Postoperative change • Pulsion diverticulum

CLINICAL ISSUES • Medical treatment and lifestyle modification (treatment same as for gastroesophageal reflux disease [GERD]) • Increasing use of laparoscopic fundoplication to treat GERD and to repair all types of HH

Hiatal Hernia

Abbreviations

– ± gastric ulcer of lesser curvature at level of diaphragmatic hiatus – Type III and IV: Prone to volvulus

• Hiatal hernia (HH)

CT Findings

Definitions

• Widening of esophageal hiatus ○ Dehiscence of diaphragmatic crura (> 15 mm); increased distance between crura and esophageal wall • Focal fat collection in middle compartment of lower mediastinum ○ Omentum herniates through phrenicoesophageal ligament ○ May see in fat surrounding distal esophagus • CT clearly demonstrates paraesophageal hernia through widened esophageal hiatus ○ Visualize size, contents, orientation of herniated stomach within lower thoracic cavity ○ Herniated contents lie alongside esophagus

• Protrusion of part of stomach through esophageal hiatus of diaphragm

IMAGING General Features • Best diagnostic clue ○ Fluoroscopy after barium meal showing some portion of stomach in thorax • 2 general types ○ Sliding (axial) – Gastroesophageal (GE) junction and gastric cardia pass through esophageal hiatus of diaphragm into thorax ○ Paraesophageal (rolling) hernia – Gastric fundus ± other parts of stomach herniate into chest • Surgical classification ○ Type I: Sliding HH (only cardia in chest) ○ Type II paraesophageal (PEH): GE junction in normal position (under diaphragm) – Fundus herniates alongside esophagus (very rare) ○ Type III PEH: GE junction in chest, along with fundus ± other portions of stomach – 2nd most common type (after type I) ○ Type IV PEH: Intrathoracic stomach ± volvulus

Radiographic Findings • Fluoroscopic-guided barium esophagram and upper GI ○ Type I (sliding HH) – Lower esophageal mucosal (B) ring observed 2 cm above diaphragmatic hiatus – Prominent diagonal notch may be seen on left lateral and superior aspect of HH □ Due to crossing gastric sling fibers at cardiac incisura – ± kink or narrowing of HH at esophageal hiatus; extrinsic compression by diaphragm – Esophageal peristaltic wave stops at GE junction – Tortuous esophagus that has eccentric junction with hernia – Often reducible in erect position – Numerous (> 6) longitudinal gastric folds within HH continue through hiatus into abdominal part of stomach □ Gastric folds converging superiorly toward point several centimeters above diaphragm – Areae gastricae pattern demonstrated within herniated portion of fundus – "Riding ulcers" at hiatal orifice □ Repeated trauma of gastric mucosa on ridge riding over hiatus ○ Paraesophageal hernia (types II to IV) – Portion of stomach anterior or lateral to esophagus in chest – Frequently nonreducible

Esophagus

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Barium esophagram and upper GI studies • Protocol advice ○ Fluoroscopic-guided single-contrast barium studies (patient prone right anterior oblique) – Obtain fully distended views in several positions, including upright – Film with full inspiration and Valsalva ○ Sensitivity: Full-column technique (100%), mucosal relief (52%), double-contrast techniques (34%)

DIFFERENTIAL DIAGNOSIS Phrenic Ampulla • Saccular, slightly more distensible distal segment of esophagus that communicates with stomach • Phrenic ampulla or vestibule corresponds to location of lower esophageal sphincter (LES) ○ 2-4 cm long high-pressure zone extends up from GE junction into thorax ○ At upper end of sphincter; muscle coalescence called A ring, B ring at lower end of ampulla at GE junction ○ Ampulla has bulbous configuration when fully distended

Postoperative Change • Esophagectomy with gastric pull-up procedure ○ Gastric conduit is pulled into chest to replace resected esophagus

Pulsion Diverticulum • Usually large sac-like protrusion in epiphrenic region; tends to remain filled after most barium is emptied • From lateral esophageal wall of distal 10 cm • Lack of gastric folds within diverticulum helps distinguish from hernia

PATHOLOGY General Features • Etiology ○ Acquired complex multifactorial etiology – Becoming more common with obesity, aging, lack of conditioning 195

Esophagus

Hiatal Hernia

– Multiparous women have increased incidence – Reflux itself induces irritation that causes spasm of longitudinal muscles of esophagus □ Shortens esophagus, which pulls stomach up into chest

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Sliding HH – Symptoms of GE reflux disease (GERD) – Substernal or epigastric burning pain, regurgitation, dysphagia, hoarse voice ○ Paraesophageal hernia (PEH) – May be asymptomatic; incidental finding on imaging – Anemia, abdominal or chest pain, vomiting □ Especially if strangulation or volvulus occur – Common in elderly with multiple other medical problems – GERD and reflux esophagitis are uncommon in PEH (according to some authors) – Others believe reflux is common, and danger of volvulus makes repair necessary • May be incidentally noted on upper GI series or CT • Found during endoscopy ○ Cameron ulcers and erosions within herniated stomach – In 5.2% of patients with HH – Acute upper GI bleeding (6.3%) – Persistent, recurrent iron deficiency anemia (8.3%) – Pathogenesis: Mechanical trauma, ischemia, acid mucosal injury

Demographics • Age ○ Prevalence increases with age • Gender ○ M 90% of all HH are sliding (type I) ○ < 10% are paraesophageal – Seem to be increasing in prevalence – May be due to age and obesity in population

Natural History & Prognosis • Sliding (type I) HH ○ Morbidity is due to associated GERD ○ incidence of Barrett esophagus, and incidence of carcinoma • Complications of PEH ○ PEHs may enlarge ○ Types III and IV at risk for volvulus, strangulation, ischemia, perforation ○ Complications of nonsurgical treatment may be sudden and severe

Treatment • Sliding HH ○ Medical treatment and lifestyle modification; treatment same as for GERD ○ Increasing use of laparoscopic fundoplication to treat GERD and to repair HH 196

• PEH ○ Surgery is warranted unless patient is prohibitive operative risk – Hernial sac excision, crural closure, and antireflux procedure (fundoplication or gastropexy) – Increasing use of laparoscopic repair has decreased morbidity of procedure

DIAGNOSTIC CHECKLIST Consider • Esophagram and upper GI series remain best test to demonstrate and classify HHs • CT (and MR) are complementary to barium studies

SELECTED REFERENCES 1. 2.

3. 4. 5. 6.

7. 8.

9.

10.

11. 12.

13. 14. 15. 16.

D'Netto TJ et al: A technique for the laparoscopic repair of paraoesophageal hernia without mesh. J Gastrointest Surg. 18(4):851-7; discussion 857, 2014 Sheikh I et al: Consumer Use of Over-the-Counter Proton Pump Inhibitors in Patients With Gastroesophageal Reflux Disease. Am J Gastroenterol. 109(6):789-94, 2014 Dean C et al: Hiatal hernias. Surg Radiol Anat. 34(4):291-9, 2012 Nason KS et al: The laparoscopic approach to paraesophageal hernia repair. J Gastrointest Surg. 16(2):417-26, 2012 Belhocine K et al: Epidemiology of the complications of gastroesophageal reflux disease. Dig Dis. 27(1):7-13, 2009 Larusson HJ et al: Predictive factors for morbidity and mortality in patients undergoing laparoscopic paraesophageal hernia repair: age, ASA score and operation type influence morbidity. World J Surg. 33(5):980-5, 2009 Yano F et al: Outcomes of surgical treatment of intrathoracic stomach. Dis Esophagus. 22(3):284-8, 2009 Granderath FA et al: Laparoscopic revisional fundoplication with circular hiatal mesh prosthesis: the long-term results. World J Surg. 32(6):999-1007, 2008 Linke GR et al: Is a barium swallow complementary to endoscopy essential in the preoperative assessment of laparoscopic antireflux and hiatal hernia surgery? Surg Endosc. 22(1):96-100, 2008 Wykypiel H et al: Laparoscopic partial posterior (Toupet) fundoplication improves esophageal bolus propagation on scintigraphy. Surg Endosc. 22(8):1845-51, 2008 Huang SY et al: Large hiatal hernia with floppy fundus: clinical and radiographic findings. AJR Am J Roentgenol. 188(4):960-4, 2007 Rantanen TK et al: Gastroesophageal reflux disease as a cause of death is increasing: analysis of fatal cases after medical and surgical treatment. Am J Gastroenterol. 102(2):246-53, 2007 Zaninotto G et al: Long-term results (6-10 years) of laparoscopic fundoplication. J Gastrointest Surg. 11(9):1138-45, 2007 Canon CL et al: Surgical approach to gastroesophageal reflux disease: what the radiologist needs to know. Radiographics. 25(6):1485-99, 2005 Insko EK et al: Benign and malignant lesions of the stomach: evaluation of CT criteria for differentiation. Radiology. 228(1):166-71, 2003 Pierre AF et al: Results of laparoscopic repair of giant paraesophageal hernias: 200 consecutive patients. Ann Thorac Surg. 74(6):1909-15; discussion 1915-6, 2002

Hiatal Hernia Esophagus

(Left) The GE junction in this patient with a type III PEH is in the chest, along with a substantial portion of the stomach. The stomach is pinched as it traverses the diaphragmatic hiatus . Type III PEHs are encountered with increased frequency. (Right) Upper GI in a patient with type IV PEH is shown. Intrathoracic stomach shows that while an air-fluid level is present within the stomach, there is no evidence of twisting or obstruction of the stomach; however, this patient is at risk for volvulus and strangulation.

(Left) Chest film in an elderly man with chest pain shows a widened mediastinum with an air-fluid level to the right of the spine and what appear to be bowel segments to the left of the thoracic spine. (Right) Axial CT in the same patient shows that most of the stomach lies within the right hemithorax and the colon lies to the left and behind the heart, along with omental fat, all herniating through a wide defect in the esophageal hiatus.

(Left) A barium enema in the same patient confirms that the splenic flexure of the colon is herniated, and there is a "waist" or compression of the colon as it traverses the hiatus. (Right) Post evacuation film from the barium enema shows barium retained within the herniated colon . Note the position of a nasogastric tube within the herniated stomach and duodenum, which is within the abdomen.

197

Esophagus

Esophageal Varices KEY FACTS

IMAGING • Uphill varices: portal venous pressure upward venous flow via dilated esophageal collaterals to superior vena cava (SVC) ○ Distal 1/3 or 1/2 of esophagus ○ More common • Downhill varices: Obstruction of SVC downward venous flow via esophageal collaterals to portal vein and inferior vena cava (IVC) ○ Upper or middle 1/3 of esophagus ○ Less common • Fluoroscopy: Tortuous, serpiginous, longitudinal radiolucent filling defects in collapsed or partially collapsed esophagus ○ After sclerotherapy varices may appear as fixed, rigid filling defects • CECT: Serpiginous periesophageal, gastric, etc. ○ Enhance as other abdominal veins

(Left) Graphic shows dilated, tortuous, submucosal collateral veins (varices) within the wall of the esophagus. (Right) Doublecontrast esophagram shows tortuous, nodular longitudinal folds, typical of varices. These are unusually well depicted, even with the esophageal lumen distended, suggesting that the varices may be thrombosed or sclerosed by endoscopic injection.

(Left) Axial CECT in a 55-yearold man with upper GI bleeding shows large esophageal varices . (Right) Esophagram in the same patient performed after endoscopic sclerosis of the varices shows fixed filling defects in the esophageal wall and lumen. The fixed nature of these mimics the appearance of the "varicoid" morphology of some esophageal carcinomas.

198

○ Esophageal, coronary ± paraumbilical: Most commonly visualized

TOP DIFFERENTIAL DIAGNOSES • Esophageal (varicoid) carcinoma ○ Thickened, tortuous folds due to submucosal spread of tumor ○ Rigid, fixed appearance; abrupt demarcation; welldefined borders • Reflux esophagitis ○ Submucosal edema may cause thickened folds • Esophageal metastases and lymphoma

CLINICAL ISSUES • Esophageal variceal hemorrhage ○ Accounts for 20-50% of all deaths from cirrhosis • Transjugular intrahepatic portosystemic shunt (TIPS) provides more physiological means of treating varices and ascites than other surgical procedures

Esophageal Varices

Definitions • Dilated tortuous submucosal venous plexus of esophagus

IMAGING General Features • Best diagnostic clue ○ Tortuous or serpiginous longitudinal filling defects on esophagography • Location ○ Uphill varices: Distal 1/3 or 1/2 of esophagus (more common) ○ Downhill varices: Upper or middle 1/3 of esophagus (less common) • Morphology ○ Tortuous dilated veins in long axis of esophagus, protruding directly beneath mucosa or in periesophageal tissue • Other general features ○ Usually due to portal hypertension (HTN) with cirrhosis or other liver diseases ○ Idiopathic varices: In patients with no portal HTN or superior vena cava (SVC) block (very rare) ○ Classification of esophageal varices based on pathophysiology – Uphill varices: portal venous pressure upward venous flow via dilated esophageal collaterals to SVC – Downhill varices: Obstruction of SVC downward venous flow via esophageal collaterals to portal vein and inferior vena cava (IVC)

Radiographic Findings • Radiography ○ Chest radiograph – Retrocardiac posterior mediastinal lobulated mass – ± mediastinal widening, abnormal azygoesophageal recess • Fluoroscopic-guided esophagography ○ Mucosal relief views – Tortuous, serpiginous, longitudinal radiolucent filling defects in collapsed or partially collapsed esophagus ○ Double-contrast study – Multiple radiolucent filling defects etched in white ○ Distended views of esophagus – Varices may be obscured ○ Varices may appear as fixed, rigid filling defects after sclerotherapy

CT Findings • NECT ○ Thickened esophageal wall, lobulated outer contour ○ Scalloped esophageal mural masses ○ Uni-/bilateral soft tissue masses (paraesophageal varices) • CECT ○ Well-defined round, tubular, or smooth serpentine structures ○ Homogeneous; enhance to same degree as adjacent veins ○ Location

– Esophageal, coronary ± paraumbilical: Most commonly visualized – Abdominal wall, perisplenic, perigastric, paraesophageal, retroperitoneal, omental, mesenteric – Commonly see spontaneous shunts develop between varices and systemic veins □ Left renal > gonadal > other intra- and retroperitoneal veins – Mesenteric varices □ Commonly form around ostomy sites in patients with portal hypertension (e.g., patient with cirrhosis due to primary sclerosing cholangitis whose ulcerative colitis was treated with colectomy)

Esophagus

TERMINOLOGY

MR Findings • T1WI and T2WI ○ Multiple areas of flow void • T1WI C+ ○ Portal venous phase (PVP) – Enhancement of varices seen

Ultrasonographic Findings • Grayscale ultrasound ○ Increased esophageal wall thickness at least 5 mm with irregular wall surface • Color Doppler ○ Hepatofugal venous flow within esophageal wall

Angiographic Findings • Conventional ○ Portal venogram – Uphill varices: May show cavernous transformation of portal vein and reversal of blood flow via splenic vein coronary vein esophageal varices

Imaging Recommendations • Helical NE + CECT • Fluoroscopic-guided esophagography ○ Position: Prone right anterior oblique (RAO) ○ Mucosal relief views; avoid repetitive swallowing

DIFFERENTIAL DIAGNOSIS Esophageal Carcinoma • May simulate varices • Varicoid carcinoma ○ Produce thickened, tortuous folds in esophagus due to submucosal spread of tumor ○ Rigid, fixed appearance; abrupt demarcation, welldefined borders • Varices change in size and shape with peristalsis, respiration, and Valsalva maneuvers • Diagnosis: Imaging and endoscopic biopsy

Reflux Esophagitis • May mimic varices • Submucosal edema may cause thickened folds • Diagnosis: Endoscopy and history

Esophageal Metastases and Lymphoma • Esophagus: Least common site within GI tract • Usually non-Hodgkin and less commonly Hodgkin 199

Esophagus

Esophageal Varices

• Patients almost always have generalized lymphoma or cancer • Primary esophageal lymphoma seen in AIDS cases • Diagnosis: Endoscopy with deep esophageal biopsy

PATHOLOGY General Features • Etiology ○ Uphill varices – Cirrhosis and portal HTN – Pathogenesis: Collateral blood flow from portal vein azygos vein SVC ○ Downhill varices – Obstruction of SVC distal to entry of azygos vein – Usually due to lung cancer, lymphoma, fibrosing mediastinitis – Pathogenesis: Collateral blood flow from SVC azygos vein IVC or portal system ○ Idiopathic varices: Exact mechanism is unknown – Postulated to be result of congenital weakness in venous channels of esophagus • Associated abnormalities ○ Cirrhosis with portal HTN ○ Normal esophageal venous drainage – Upper 1/3 of esophagus: Via intercostal, bronchial, and inferior thyroid veins – Middle 1/3: Via azygous and hemiazygos venous systems – Distal 1/3: Via periesophageal plexus of veins coronary vein splenic vein

Gross Pathologic & Surgical Features • Tortuous dilated veins in long axis of esophagus

Microscopic Features • Tortuous, serpiginous, dilated veins protruding beneath mucosa • ± superficial ulceration, inflammation, blood clot

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic until rupture – Usually discovered on imaging (e.g., CECT for cirrhosis) ○ Uphill varices: Hematemesis/mild bleeding (melena) ○ Downhill varices: SVC syndrome – Facial, periorbital, neck, bilateral arm swelling – Dilated superficial veins over chest ○ Lab data: Guaiac-positive stool or iron deficiency anemia • Clinical profile ○ Patient with history of cirrhosis, portal HTN, hematemesis/melena, facial/arm swelling

Demographics • Age ○ Middle-aged and elderly • Gender ○ M=F • Epidemiology ○ Incidence: 30-70% cases of cirrhosis and portal HTN 200

Natural History & Prognosis • Complications ○ Inflammation, ulceration, hemorrhage, hematemesis ○ Esophageal variceal hemorrhage – Common cause of acute upper GI bleeding – Alcoholic cirrhosis: Most prevalent cause in USA – Accounts for 20-50% of all deaths from cirrhosis □ May be less now due to transjugular intrahepatic portosystemic shunt (TIPS) and transplantation • Prognosis ○ Varices without bleeding – Usually good after treatment ○ Varices with massive bleeding – Poor ± treatment

Treatment • Nonbleeding varices ○ -blocker medication or esophageal variceal ligation • Bleeding varices ○ Vasopressin infusion ○ Balloon tamponade (Sengstaken-Blakemore tube) ○ Endoscopic sclerotherapy or variceal ligation ○ TIPS: Has largely replaced surgical shunts

DIAGNOSTIC CHECKLIST Consider • Lack of change for thick folds should suggest esophagitis or cancer rather than varices

Image Interpretation Pearls • Mucosal relief views: Tortuous, serpiginous, longitudinal radiolucent filling defects in collapsed esophagus

Reporting Tips • Estimate size of varices on CT interpretation ○ Correlates with likelihood of hemorrhage

SELECTED REFERENCES 1.

2. 3. 4.

5.

Aguilar-Olivos N et al: Hemodynamic effect of carvedilol vs. propranolol in cirrhotic patients: Systematic review and meta-analysis. Ann Hepatol. 13(4):420-8, 2014 Hong WD et al: Predictors of esophageal varices in patients with HBVrelated cirrhosis: a retrospective study. BMC Gastroenterol. 9:11, 2009 Sass DA et al: Portal hypertension and variceal hemorrhage. Med Clin North Am. 93(4):837-53, vii-viii, 2009 Kang HK et al: Three-dimensional multi-detector row CT portal venography in the evaluation of portosystemic collateral vessels in liver cirrhosis. Radiographics. 22(5):1053-61, 2002 Matsumoto A et al: Three-dimensional portography using multislice helical CT is clinically useful for management of gastric fundic varices. AJR Am J Roentgenol. 176(4):899-905, 2001

Esophageal Varices Esophagus

(Left) Axial CECT in a middleaged man with cirrhosis demonstrates cirrhosis but relatively small esophageal varices. The portal vein was thrombosed (not shown). (Right) Axial CECT in the same patient shows large perisplenic varices and calcification present in the walls of some varices that might be mistaken for arterial aneurysms.

(Left) Axial CECT in the same patient shows a spontaneous splenorenal shunt with enlargement of the left renal vein . Spontaneous or surgically created shunts help to decompress esophageal varices but increase the incidence of encephalopathy and portal vein thrombosis, making subsequent liver transplantation difficult or impossible. (Right) Celiac arteriogram in the same patient shows opacification of the splenic vein and varices but no portal vein flow.

(Left) Axial CECT in an elderly woman presenting with a puffy face shows obstruction of superior vena cava (SVC) with collateral flow through an enlarged azygous vein and various mediastinal collateral veins. (Right) Coronal CECT (same patient) shows enlarged azygous vein and mediastinal collateral veins . The collaterals are carrying flow from tributaries of the SVC into abdominal circulation to be returned to the heart via the inferior vena cava (IVC). These are sometimes referred to as "downhill varices."

201

Esophagus

Zenker Diverticulum KEY FACTS

• Mucosal herniation through area of anatomic weakness just above cricopharyngeal muscle (Killian triangle)

○ Protrudes laterally • Esophageal webs • Epidermolysis and pemphigoid

IMAGING

CLINICAL ISSUES

• Barium-filled sac posterior to cervical esophagus ○ Opening into pouch just above cricopharyngeus muscle (C5-6 level) ○ Prominent or thickened cricopharyngeal muscle ○ Luminal narrowing at pharyngoesophageal junction due to extrinsic compression ○ Large diverticulum may protrude laterally to left or compress cervical esophagus • Almost all patients have associated esophageal dysmotility, often with hiatal hernia and GERD

• Upper esophageal dysphagia ○ Regurgitation and aspiration of undigested food • Complications ○ Risk of perforation during endoscopy or placement of nasogastric tube ○ Aspiration pneumonia (in 30% of cases) ○ Risk of carcinoma (seen in 0.3% of cases) • Treatment: Surgical diverticulectomy or endoscopic repair

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • Killian-Jamieson diverticulum ○ Opening below cricopharyngeus muscle

(Left) Graphic shows a pouchlike herniation through the Killian dehiscence just above cricopharyngeal muscle. (Right) Lateral view of a barium swallow shows a large pouch arising from the posterior pharyngoesophageal junction.

(Left) Film from a barium esophagram shows a large diverticulum arising from the pharyngoesophageal junction and extending into the mediastinum. The esophagus is displaced, and its lumen is compressed by the diverticulum. Note the barium aspirated into the trachea . (Right) Axial NECT in the same patient shows the diverticulum filled with debris, fluid, and gas. Large diverticula often compress the lumen of the esophagus and extend to 1 side of the midline due to mass effect.

202

DIAGNOSTIC CHECKLIST • Following repair of Zenker diverticulum, residual outpouching will still be seen in most cases

Zenker Diverticulum

Synonyms • Pharyngoesophageal diverticulum or posterior hypopharyngeal diverticulum/outpouching

Definitions • Outpouching of mucosa through Killian triangle, an area of muscular weakness between transverse fibers of cricopharyngeus and oblique fibers of lower inferior constrictor

IMAGING General Features • Best diagnostic clue ○ Barium-filled sac posterior to cervical esophagus • Location ○ Pharyngoesophageal junction – Killian dehiscence (triangular anatomical area of weakness) – Midline posterior wall of pharyngoesophageal segment just above cricopharyngeus muscle (C5-6 level) □ Formed by oblique fibers of inferior pharyngeal constrictor muscle and cricopharyngeal sphincter – Area of weakness occurs in 1/3 of patients • Size ○ Average maximal dimension: 2.5 cm ○ Range: 0.5-8 cm • Morphology ○ Posterior hypopharyngeal saccular outpouching with neck opening above cricopharyngeus muscle • Zenker diverticulum is false diverticulum ○ Presence of mucosa and submucosa, no muscle • Almost all patients have associated esophageal dysmotility, often with hiatal hernia and gastroesophageal reflux disease (GERD) • On barium studies: Any irregularity of contour of Zenker diverticulum suggests either inflammatory or neoplastic complication

Radiographic Findings • Radiography ○ Chest x-ray – May show air-fluid level in superior mediastinum • Fluoroscopic-guided barium study ○ Frontal view – Barium-filled sac below level of hypopharynx – Large diverticulum: Extends inferiorly into mediastinum ○ Lateral or oblique view – Barium-filled sac posterior to cervical esophagus – Neck of diverticulum with its opening into posterior hypopharyngeal wall above cricopharyngeus muscle – Prominent or thickened cricopharyngeal muscle – Luminal narrowing of proximal esophagus due to extrinsic compression □ Persists after passage of bolus through esophagus – ± nasopharyngeal regurgitation ○ During swallowing

– Diverticulum appears as posterior bulging of distal pharyngeal wall above anteriorly protruding pharyngoesophageal segment (cricopharyngeal muscle) ○ At rest – Barium-filled diverticulum extends below level of cricopharyngeal muscle and is posterior to cervical esophagus – Large diverticulum may protrude laterally to left or compress cervical esophagus ○ After swallowing – Regurgitation or emptying of barium into hypopharynx ○ Pseudo-Zenker diverticulum is important potential pitfall – Barium trapped between peristaltic wave and prominent cricopharyngeal muscle or early closure of upper cervical esophagus – Does not extend posteriorly beyond contour of cervical esophagus – After peristaltic wave has passed, during suspended respiration, trapped barium is cleared and pseudoZenker diverticulum is not evident

Esophagus

TERMINOLOGY

Imaging Recommendations • Fluoroscopic-guided pharyngoesophagram • AP, lateral, and oblique views • Lateral view during suspended respiration ○ To rule out pseudo-Zenker diverticulum

DIFFERENTIAL DIAGNOSIS Killian-Jamieson Diverticulum • Transient or persistent protrusions of anterolateral cervical esophagus into Killian-Jamieson (KJ) space (lateral cervical esophageal pouch or diverticulum) • Morphology ○ Round to oval, smooth-surfaced outpouching • Location ○ Seen in anterolateral wall of cervical esophagus (triangular area of weakness) – Just below cricopharyngeus muscle • Size: 3-20 mm in diameter • Less common and smaller than Zenker diverticulum • Less likely to cause symptoms • Less likely to be associated with overflow aspiration or gastroesophageal (GE) reflux than Zenker diverticulum • Fluoroscopic-guided barium study ○ Frontal views – Appears as shallow and broad-based protrusion – Location: Lateral upper esophageal wall – Fills late during swallowing; empties late after swallowing ○ Lateral views – Barium-filled saccular protrusions – Neck of KJ diverticulum opening below level of cricopharyngeus muscle – Zenker diverticulum: Neck opens into posterior hypopharyngeal wall above cricopharyngeus muscle (C5-6 level) and sac extends inferiorly behind cervical esophagus

203

Esophagus

Zenker Diverticulum

Esophageal Webs

Natural History & Prognosis

• Radiolucent ring in proximal cervical esophagus near cricopharyngeus • On imaging ○ 1-2 mm wide, shelf-like filling defect along anterior wall of cervical esophagus ○ Mild, moderate, or severe luminal narrowing

• Complications ○ Aspiration pneumonia (in 30% of cases) ○ Bronchitis, bronchiectasis, lung abscess ○ Diverticulitis, ulceration, fistula formation ○ Risk of perforation during endoscopy or placement of nasogastric tube ○ Risk of carcinoma (seen in 0.3% of cases) • Associated abnormalities ○ 15-20% have Barrett esophagus • Prognosis ○ Usually good after surgery ○ Poor prognosis: Neoplastic complication

Epidermolysis and Pemphigoid • Stricture and proximal dilatation of cervical esophagus • Cervical esophageal webs near cricopharyngeus (or lower) • High-esophageal strictures or webs in children or young adults with clinical history suggests diagnosis

PATHOLOGY General Features • Etiology ○ Cricopharyngeal dysfunction (achalasia, spasm, premature closure); intraluminal pressure ○ Spasm, incoordination, or abnormal relaxation of upper esophageal sphincter (achalasia) ○ Other contributing factors to development of Zenker diverticulum – GE reflux – Reflux esophagitis – Hiatal hernia – Esophageal spasm and achalasia • Associated abnormalities ○ GE reflux ○ Reflux esophagitis, hiatal hernia • False diverticulum ○ Only mucosa and submucosa are present ○ No muscle tissue

Gross Pathologic & Surgical Features • Posterior hypopharyngeal saccular outpouching with broad or narrow neck

Microscopic Features • Mucosal and submucosal layers of hypopharynx • Lack of muscle

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Upper esophageal dysphagia ○ Regurgitation and aspiration of undigested food ○ Halitosis, choking, hoarseness, neck mass ○ Some patients are asymptomatic

Demographics • Age ○ More common in elderly ○ 50% of cases seen in 7th-8th decade • Gender ○ M>F • Epidemiology ○ Prevalence: 1% of patients with dysphagia ○ 2 per 100,000 general population 204

Treatment • Small asymptomatic diverticula: No treatment • Asymptomatic and symptomatic large diverticula ○ Surgical diverticulectomy or endoscopic repair ± cricopharyngeal myotomy • Treat underlying esophageal motility disorder

DIAGNOSTIC CHECKLIST Consider • Differentiate from Killian-Jamieson diverticula

Image Interpretation Pearls • Following repair of Zenker diverticulum, residual outpouching will still be seen in most cases

SELECTED REFERENCES 1.

Prisman E et al: Zenker diverticulum. Otolaryngol Clin North Am. 46(6):110111, 2013 2. Fama AF et al: Harmonic scalpel in the treatment of Zenker's diverticulum. Laryngoscope. 119(7):1265-9, 2009 3. Grant PD et al: Pharyngeal dysphagia: what the radiologist needs to know. Curr Probl Diagn Radiol. 38(1):17-32, 2009 4. Hillel AT et al: Evolution of endoscopic surgical therapy for Zenker's diverticulum. Laryngoscope. 119(1):39-44, 2009 5. Osammor JY: Excision of Zenker's diverticulum: a new surgical approach. Clin Otolaryngol. 34(1):85-6, 2009 6. Skrobić OM et al: Current concepts in the anatomy and origin of pharyngeal diverticula. Acta Chir Iugosl. 56(1):17-24, 2009 7. Syamal MN et al: Operative adaptation for endoscopic identification of Zenker's diverticulum. Laryngoscope. 119(5):861-3, 2009 8. Sakai P: Endoscopic treatment of Zenker's diverticulum. Gastrointest Endosc. 65(7):1054-5, 2007 9. Ibrahim IM: Zenker diverticulum. Arch Surg. 138(1):111, 2003 10. Postma GN: RE: endoscopic diverticulotomy of Zenker's diverticulum: management and complications (Dysphagia 17:34-39). Dysphagia. 18(3):227; author reply 227-8, 2003 11. Rubesin SE et al: Killian-Jamieson diverticula: radiographic findings in 16 patients. AJR Am J Roentgenol. 177(1):85-9, 2001 12. Sydow BD et al: Radiographic findings and complications after surgical or endoscopic repair of Zenker's diverticulum in 16 patients. AJR Am J Roentgenol. 177(5):1067-71, 2001

Zenker Diverticulum Esophagus

(Left) One of a rapid sequence series of spot films demonstrates a typical Zenker diverticulum as a blind-ending pouch arising from the pharyngoesophageal junction (around the C5-6 level). The esophageal lumen is displaced and compressed by the filled diverticulum. (Right) A slightly later film from the sequence shows that the pouch remains filled after the bolus has passed through the esophagus. The esophageal lumen is still compressed by the filled diverticulum.

(Left) Chest radiograph in an elderly woman was obtained following attempted placement of a feeding tube , which is coiled within the mediastinum. (Right) A barium esophagram in the same patient confirms a large diverticulum extending down into the chest.

(Left) A lateral view from the same esophagram confirms a large diverticulum arising from the pharyngoesophageal junction, which displaces the esophagus and trachea forward. (Right) In this elderly man with chest pain following the attempted placement of feeding tube, film from an esophagram shows a retroesophageal and mediastinal collection of gas and water-soluble contrast medium . The track runs parallel to the course of the proximal esophagus . A perforated Zenker diverticulum was confirmed.

205

Esophagus

Intramural Pseudodiverticulosis KEY FACTS

TERMINOLOGY • Rare benign disorder characterized by esophageal diverticulosis-like outpouchings • Caused by dilation of excretory ducts of deep mucous glands • Associated with esophagitis and stricture ± motility disorders

IMAGING • Barium esophagram more sensitive than endoscopy • Innumerable tiny barium-filled outpouchings ○ In longitudinal rows parallel to long axis of esophagus ○ Flask-shaped, 1-4 mm ○ Incomplete filling may erroneously suggest lack of communication with esophageal lumen • Intramural tracks: Bridging between adjacent pseudodiverticula ○ More likely to occur with diffuse form of intramural pseudodiverticulosis (IPD)

(Left) Endoscopic photograph shows the opening of innumerable pseudodiverticula, many arranged in orderly, longitudinal rows. (Right) Spot film from a barium esophagram demonstrates the classic finding of innumerable tiny collections of barium within the esophageal wall. Decreased primary peristalsis and tertiary contractions were also evident on fluoroscopy.

(Left) Two views from a double-contrast esophagram reveal innumerable tiny flaskshaped outpouchings along the entire length of the esophagus, findings pathognomonic of pseudodiverticulosis. (Right) Film from a barium esophagram demonstrates a small hiatal hernia and a short peptic stricture of the distal esophagus. There are numerous intramural pseudodiverticula within the strictured segment as well as more proximally.

206

• Stricture: Pseudodiverticula often extend above and below level of stricture ○ Stricture could be benign or malignant

TOP DIFFERENTIAL DIAGNOSES • Esophagitis ○ Multiple discrete ulcers associated with various types of esophagitis ○ True ulcers communicate directly with lumen ○ Ulcers, strictures, and pseudodiverticula can occur together

DIAGNOSTIC CHECKLIST • Periodic surveillance of patients with IPD for esophageal carcinoma

Intramural Pseudodiverticulosis

Abbreviations • Intramural pseudodiverticulosis (IPD)

Definitions • Rare benign disorder characterized by esophageal diverticulosis-like outpouchings ○ Caused by dilation of excretory ducts of deep mucous glands

IMAGING General Features • Best diagnostic clue ○ Barium esophagram more sensitive than endoscopy • Location ○ Wall of thoracic esophagus ○ Diffuse (50%) or segmental involvement • Size ○ Outpouchings: Tiny, usually 1-4 mm ○ Intramural tracks: Average length 1.2 cm – Range = 0.3-7 cm • Morphology ○ Multiple flask-shaped outpouchings

Radiographic Findings

○ Pseudodiverticula seem to be floating outside, without apparent communication with lumen • Ulcers, strictures, and pseudodiverticula can occur together

PATHOLOGY General Features • Etiology and pathogenesis are largely unknown ○ Inflammation, resulting in periductal fibrosis and compression of duct orifices, may be causative factor • Associated abnormalities ○ Chronic esophagitis, gastroesophageal reflux ○ Esophageal strictures ○ Candidiasis, motility disorders ○ Esophageal web formation; may be underreported ○ Chronic alcoholism (15%), diabetes mellitus (20%)

Gross Pathologic & Surgical Features • Numerous intramural pouches; stricture

CLINICAL ISSUES Presentation • Intermittent or slowly progressive dysphagia • Associated diseases are almost always present • Diagnosis: Esophagram (findings pathognomonic) ○ Endoscopy: Orifices of ducts difficult to visualize

• Outpouchings: Innumerable, barium-filled, tiny; in longitudinal rows parallel to long axis of esophagus ○ Neck 1 mm in diameter – Incomplete filling may erroneously suggest lack of communication with esophageal lumen ○ Inflammatory debris may prevent barium from entering ducts failure to visualize pseudodiverticula • Intramural tracks: Bridging between adjacent pseudodiverticula ○ More likely to occur with diffuse form of IPD ○ Mistaken for large flat ulcer or extramural collection • Large, irregular extraluminal collection of barium (rare) ○ Due to massive ductal dilatation or sealed-off perforation of duct • Stricture: Of varying length (pseudodiverticula often extend above and below level of stricture) ○ Stricture could be benign or malignant

Demographics

CT Findings

Treatment

• Thick esophageal wall, narrow lumen • Intramural gas collections • Peridiverticulitis and abscess formation ○ Due to perforation (rare)

• Strictures: Balloon or bougie dilatation

Imaging Recommendations

• Periodic surveillance of patients with IPD for esophageal carcinoma

• Esophagram: Frontal, lateral, oblique views

DIFFERENTIAL DIAGNOSIS Esophagitis • Multiple discrete ulcers associated with various types of esophagitis • Viewed en face, pseudodiverticula mistaken for ulcers • True ulcers communicate directly with lumen

Esophagus

TERMINOLOGY

• Age ○ Seen in adults, most commonly 45-65 years • Gender ○ M:F = 3:2 • Epidemiology ○ Rare condition; diagnosed in < 1% of patients undergoing esophagography

Natural History & Prognosis • Pseudodiverticula themselves rarely cause problems • Often noted to disappear after esophageal dilation but may persist asymptomatically in some patients • Complications: Perforation, peridiverticulitis, mediastinitis secondary to ruptured IPD • Prevalence of IPD significantly higher in patients with esophageal carcinoma

DIAGNOSTIC CHECKLIST Consider

SELECTED REFERENCES 1. 2.

Halm U et al: Esophageal intramural pseudodiverticulosis: endoscopic diagnosis and therapy. Dis Esophagus. 27(3):230-4, 2014 Plavsic BM et al: Intramural pseudodiverticulosis of the esophagus detected on barium esophagograms: increased prevalence in patients with esophageal carcinoma. AJR Am J Roentgenol. 165(6):1381-5, 1995

207

Esophagus

Traction Diverticulum KEY FACTS

IMAGING • Acquired condition due to subcarinal or perihilar granulomatous lymph node pathology ○ Similar lesion may represent a pulsion diverticulum, due to esophageal dysmotility • Chest x-ray PA view: Calcified perihilar lymph nodes • Videofluoroscopic esophagogram (barium studies) ○ Mid esophagus: Traction diverticulum ○ Tented or triangular in shape with pointed tip, wide mouth ○ Diverticulum tends to empty when esophagus is collapsed (because it contains all layers)

TOP DIFFERENTIAL DIAGNOSES • Zenker diverticulum ○ Posterior hypopharyngeal diverticulum • Pulsion diverticulum

○ Mid and distal esophageal pulsion diverticula tend to remain filled after most of barium is emptied (lack of muscle) ○ Associated with motility disorders • Esophageal perforation ○ Sealed-off leak seen as self-contained extraluminal collection of contrast medium that communicates with adjacent esophagus ○ May be indistinguishable from traction diverticulum without history

PATHOLOGY • Pathogenesis: Acutely inflamed, enlarged subcarinal nodes indent and adhere to esophageal walls ○ As inflammation subsides, nodes shrink and retract adherent esophagus

CLINICAL ISSUES • Small diverticula: Usually asymptomatic • Large diverticula: ± dysphagia or regurgitation

(Left) Graphic shows subcarinal lymph nodes that are adherent to the esophageal wall, resulting in a traction diverticulum . (Right) Spot film from an esophagram shows a bariumfilled tented outpouching from the mid esophagus. Calcified subcarinal lymph nodes were more evident on chest radiograph (not shown).

(Left) Oblique view from a barium esophagram demonstrates a saccular outpouching from the mid esophagus just below the tracheal carina, a typical appearance for a traction diverticulum. (Right) Spot film from a barium esophagram shows a focal outpouching from the left mid esophagus. Although this may represent a traction diverticulum, it may rather be a normal outpouching of the esophageal wall between the extrinsic indentations by the aortic arch and the left mainstem bronchus.

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Pulsion Diverticulum

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Esophageal saccular protrusion or outpouching; pseudodiverticulum (only mucosal layer)

• Hiatal hernia (especially type 3 paraesophageal hernia) ○ Look for gastric folds within hernia • Traction diverticulum • Esophageal perforation

IMAGING • Proximal esophagus: Zenker diverticulum • Mid esophageal pulsion diverticula ○ Barium-filled outpouchings from esophagus ○ Usually smooth, rounded contour and wide neck ○ Diverticula tend to remain filled after most of barium is emptied due to lack of muscle in wall ○ Single or multiple, of varied sizes ○ Almost all patients have evidence of diffuse esophageal spasm or significant dysmotility • Distal esophageal (epiphrenic) pulsion diverticula ○ Large barium-filled sac in epiphrenic area ○ Easily mistaken for hiatal hernia

Esophagus

KEY FACTS

CLINICAL ISSUES • Small diverticula: Usually asymptomatic • Large diverticula: Dysphagia, regurgitation, halitosis • Complications ○ Perforation, fistula formation, retained foreign body – Perforation by feeding tube or endoscope is known hazard of pulsion diverticula • Treatment: Surgical diverticulectomy (endoscopically) ○ Caution: Patients almost always have some residual diverticulum, which may be mistaken for postoperative leak or recurrence

(Left) Esophagram in an elderly patient with dysphagia and halitosis shows a large epiphrenic diverticulum and esophageal dysmotility with tertiary contractions . (Right) Axial NECT in the same patient shows the large epiphrenic diverticulum containing contrast and retained food. The retained food accounts for the symptom of halitosis.

(Left) Two views from a barium esophagram demonstrate deep, nonpropulsive, tertiary contractions and a pulsion diverticulum . Pulsion diverticula are almost always associated with esophageal motility disturbances and become more common with advanced age. (Right) Spot film from an esophagram shows a large epiphrenic (pulsion) diverticulum that could be mistaken for a type III paraesophageal hernia. Note the wide mouth and absence of gastric folds within the diverticulum.

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Esophagus

Esophageal Foreign Body KEY FACTS

IMAGING

• Esophagitis

• History of ingestion followed by dysphagia or odynophagia • Chest radiograph: Coins and flat objects orient in coronal plane if within esophagus • Lateral neck radiograph: Radiopaque foreign body (FB) ○ Bones tend to lodge in cervical esophagus, just below level of cricopharyngeus muscle (C6 level) ○ Ingested bone fragments: Linear or slightly curved ○ Diffuse widening of retropharyngeal soft tissue • Large food bolus; unchewed meat ○ Above stricture, Schatzki ring, or tumor ○ Barium-soaked cotton ball, marshmallow; helps identify nonopaque, small FB • Follow-up esophagram after removal of FB ○ Underlying disease, motor function, patency ○ Check for injury to esophagus

CLINICAL ISSUES

TOP DIFFERENTIAL DIAGNOSES • Esophageal carcinoma

(Left) Barium esophagram shows complete obstruction of the esophageal lumen and a filling defect representing an incompletely chewed piece of meat. Following removal, a Schatzki ring was found. (Right) This 1-year-old child swallowed a watch battery , which is lodged in the cervical esophagus. Note the smooth outer contour that distinguishes it from the serrated surface of a coin. The coin was removed, but resulted in a persistent stricture of the esophagus.

(Left) Esophagram demonstrates the outline of a plastic comb impacted in the distal esophagus and extending into the stomach. On first impression, this might be misinterpreted as an esophageal stent that had been placed across an obstructing esophageal lesion. (Right) Oblique esophagram following endoscopic removal of a foreign body shows extravasation of contrast medium and free air within the abdomen . Surgical repair was required.

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• Majority occur in children • High-risk adults include ○ Mentally impaired ○ Those with esophageal motility or morphologic abnormalities ○ Those who habitually hold nails or pins with their lips • Management depends on type, size, location of FB ○ Most FB pass spontaneously ○ Disk batteries are toxic and should be removed • Endoscopic extraction: Flexible fiberoptic ○ Successful removal rates as high as 92-98%, with uncommon complications • Fluoroscopically guided: Balloon-tipped Foley or Fogarty catheter; Dormia-type wire basket

Esophageal Foreign Body

Abbreviations • Esophageal foreign body (FB)

Definitions • Ingested FB impacted within esophagus

IMAGING General Features • Best diagnostic clue ○ History of ingestion followed by dysphagia or odynophagia • Location ○ Gastroesophageal junction: Area of indentation by aortic arch or left main bronchus ○ Above preexisting stricture, Schatzki ring, or tumor ○ Bones tend to lodge in cervical esophagus, just below level of cricopharyngeus muscle (C6 level) • Size ○ Smooth objects measuring < 1-2 cm in diameter usually pass uneventfully • Morphology ○ Radiolucent: Food, plastic, wood, medication, etc. ○ Radiopaque: Coin, battery, pin, nail, needle, etc. ○ Sharp or dull, pointed or blunt, toxic or nontoxic

Radiographic Findings • Radiography ○ Lateral neck radiograph: Radiopaque FB – Ingested bone fragments: Linear or slightly curved densities with well-defined margins – Radiolucent FB: Indirect evidence of mucosal trauma; localized soft tissue emphysema, lump – Diffuse widening of retropharyngeal soft tissue ○ Chest radiograph: Coins and flat objects orient in coronal plane if within esophagus

Fluoroscopic Findings • Barium swallow: Performed early to determine presence of FB and obstruction ○ Animal/fish bone: Easily obscured by barium • Large food bolus, unchewed meat ○ May cause complete esophageal obstruction ○ Polypoid filling defect with irregular meniscus ○ Barium outlining superior border of food bolus ○ With incomplete obstruction, small amount of barium may trickle into distal esophagus, stomach ○ May erroneously suggest stricture; esophagus incompletely distended below level of impaction • Barium-soaked cotton ball/marshmallow helps identify nonopaque, small FB • Follow-up esophagram after removal of FB ○ Underlying disease, motor function, lumen patency, mucosal injury induced by FB or its removal

CT Findings • May detect faintly opaque bone • Localized soft tissue emphysema, edema, hematoma, or abscess; may see FB penetrating esophageal wall

Imaging Recommendations • Protocol advice ○ Lateral film of neck, upright position, neck well extended, phonation: More informative than anteroposterior view ○ Water-soluble iodinated contrast if perforation suspected; if no leakage seen, repeat with barium

Esophagus

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Esophageal Carcinoma • May appear as filling defect in esophageal lumen

Esophagitis • Candida infection or viral • May cause fibrinous exudate (pseudotumor)

PATHOLOGY General Features • Etiology ○ Children: Anything that will fit into mouth ○ Adults: Animal/fish bones, or boluses of meat • Associated abnormalities ○ Underlying webs, rings, or strictures (adults)

CLINICAL ISSUES Presentation • High-risk adults include ○ Mentally impaired ○ Those with underlying esophageal motility or morphologic abnormality ○ Those who habitually hold nails, needles, etc., with their lips • Diagnosis: History (by patient or observer)

Demographics • Epidemiology ○ 80% of FB impactions occur in children

Natural History & Prognosis • Most FB pass spontaneously through gastrointestinal tract without difficulty • Sharp, pointed, elongated FB: Associated with greater risk of perforation, vascular penetration, fistula • Successful removal rates as high as 92-98%, with uncommon complications

Treatment • Management depends on type, size, and location of FB ○ Disk batteries (e.g., watch batteries) are toxic and should be removed • Endoscopic extraction: Flexible fiberoptic • Fluoroscopically guided: Balloon-tipped Foley or Fogarty catheter, Dormia-type wire basket • Surgical removal: Rarely indicated for complications

SELECTED REFERENCES 1.

Sahn B et al: Review of Foreign Body Ingestion and Esophageal Food Impaction Management in Adolescents. J Adolesc Health. ePub, 2014

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Esophagus

Esophageal Perforation KEY FACTS

IMAGING • Diagnosis depends on high degree of suspicion and recognition of clinical features ○ Majority are due to esophageal instrumentation ○ Confirmed by contrast esophagram or CT, which are complementary • Cervical esophageal perforation (EP) ○ Subcutaneous or interstitial emphysema; neck and mediastinum ○ Consider perforation of Zenker diverticulum • Thoracic EP ○ Chest film: Pneumomediastinum, pleural effusion • EP of intraabdominal segment of distal esophagus ○ Abdominal plain film: Pneumoperitoneum • EP near GE junction ○ Extravasated contrast from left lateral aspect of distal esophagus into mediastinum, sometimes pleural space, and rarely abdomen (never abdomen alone)

(Left) Barium esophagrams reveal a tight stricture at the gastroesophageal (GE) junction . Due to concern for Barrett metaplasia or early cancer, an endoscopic biopsy of the lesion was performed following balloon dilation of the stricture. (Right) Postbiopsy esophagram in the same patient illustrates a focal intramural barium collection , indicating a localized perforation. These intramural perforations will usually heal spontaneously.

(Left) Esophagram in a 62year-old man with a history of laparoscopic hiatal hernia repair, now presenting with subsequent chest pain and fever, demonstrates mediastinal and abdominal extraluminal collections of gas and contrast material. (Right) Axial CECT in the same patient reveals mediastinal and abdominal extraluminal collections of gas and contrast material, indicating perforation near the GE junction. Surgical drainage was successful.

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• CT shows extraesophageal air in almost all cases, fluid and contrast medium in most • Intramural EP: Extravasated gas and contrast remain within esophageal wall ○ Much better prognosis • Esophagography: Technique ○ Esophagram: Videofluoroscopic and rapid sequence filming ○ Nonionic water-soluble contrast media (e.g., Omnipaque) initially, followed with barium if no leak or fistula seen ○ Barium (or CT) may detect small leak not visible initially

TOP DIFFERENTIAL DIAGNOSES • • • • •

Esophageal diverticulum Esophageal ulceration Boerhaave syndrome Postoperative state, esophagus Tracheobronchial aspiration

Esophageal Perforation

Abbreviations • Esophageal perforation (EP)

Synonyms • Esophageal rupture or transection

Definitions • Transmural esophageal tear

IMAGING General Features • Best diagnostic clue ○ Diagnosis depends on high degree of suspicion and recognition of clinical features – Confirmed by contrast esophagram or CT • Location ○ Cervical EP: Posterior wall of esophagus at level of cricopharyngeus muscle – Or through Zenker diverticulum ○ Thoracic EP: At or near gastroesophageal (GE) junction – Areas of anatomic narrowing, sites of extrinsic compression by aortic arch or L main bronchus ○ At or above benign or malignant strictures ○ Site of ruptured anastomosis or after esophageal surgery

• Sealed-off EP: Self-contained extraluminal collection of contrast medium • Larger EP: Free extravasation of contrast medium into mediastinum ○ Extension along fascial planes superiorly or inferiorly

CT Findings • • • •

Optimal definition of extraluminal manifestations Extraesophageal air in 92% of cases Extraluminal oral contrast in most Mediastinal fluid collections (92%): Periesophageal, pleural, pericardial • Diffuse infiltration of mediastinal fat (mediastinitis) • Esophagopleural fistula

Imaging Recommendations • Protocol advice ○ Esophagram: Videofluoroscopic and rapid sequence filming – Nonionic water-soluble contrast media (e.g., Omnipaque) initially, followed with barium if no leak or fistula seen – Water-soluble contrast agent may fail to detect 1525% of thoracic EP, 50% of cervical EP □ Barium may detect small leak not visible initially – CT may detect leaks missed by esophagram

DIFFERENTIAL DIAGNOSIS

Radiographic Findings

Esophageal Diverticulum

• Radiography ○ Cervical EP: Anteroposterior, lateral films of neck – Subcutaneous or interstitial emphysema – Lateral film: Widening of prevertebral space – Retropharyngeal abscess; mottled gas, air-fluid level – Air may dissect along fascial planes from neck into chest, pneumomediastinum, or vice versa ○ Thoracic EP: Chest radiograph – Pneumomediastinum □ Radiolucent gas streaks along lateral border of aortic arch, descending aorta – V-shaped radiolucency seen through heart – Sympathetic left pleural effusion; atelectasis in basilar segment – Pleural effusion, hydropneumothorax, localized pneumonitis due to esophageal-pleural fistula – Hydropneumothorax: On left (75%), on right (5%), bilateral (20%) – Hydrothorax: Usually unilateral, right sided with upper-/mid-EP; left sided with distal EP – EP of intraabdominal segment of distal esophagus □ Abdominal plain film: Pneumoperitoneum

• Mucosa-lined pouch; changes shape • No free mediastinal gas or inflammation

Fluoroscopic Findings • Esophagography: Determine site and extent of EP • Intramural EP: Extravasated gas and contrast remain within esophageal wall ○ Much better prognosis • EP near GE junction ○ Extravasated contrast from left lateral aspect of distal esophagus into mediastinum, sometimes pleural space, and rarely abdomen (never abdomen alone)

Esophagus

TERMINOLOGY

Esophagitis, Reflux • Mucosal inflammatory changes • From reflux, infection, caustic ingestion, etc.

Boerhaave Syndrome • Spontaneous distal EP; violent retching, vomiting • Extraluminal gas/contrast material in lower mediastinum surrounding esophagus • 1-4 cm, vertically oriented, linear tears on left lateral wall just above GE junction

Postoperative State, Esophagus • Postesophagectomy anatomy can be misinterpreted ○ Irregular contour near anastomosis site • Intramural linear collections are common on esophagram following Heller myotomy

Tracheobronchial Aspiration • Contrast material in trachea or bronchi • Differentiate esophageal airway fistula from aspiration ○ Initial swallow in lateral projection with video recording of hypopharynx should detect aspiration

PATHOLOGY General Features • Etiology ○ Iatrogenic – Instrumentation: Most common cause of EP

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Esophagus

Esophageal Perforation

○

○ ○

○

– Endoscopic procedures: 75-80% of all EP; rigid and fiberoptic endoscopy – Biopsy, esophageal surgery, bouginage, breakdown of surgical anastomoses – Sengstaken-Blakemore tubes (35%) – Flexible endoluminal prosthesis (10%) – Pneumatic balloon dilation (2-10%) – Esophageal obturator airways (2%) – Nasogastric or endotracheal tubes, feeding tubes □ Often perforate through abnormal esophagus (e.g., Zenker or pulsion diverticulum) – Sclerosis therapy (Rx) for esophageal varices – Radiofrequency ablation Rx for atrial fibrillation Trauma – Penetrating injuries: Knife or bullet wounds – Blunt trauma to chest or abdomen (rare) Foreign bodies – Impacted bones, sharp objects, caustic agents Spontaneous – Boerhaave syndrome – intrathoracic pressure, coughing, weightlifting, childbirth, status asthmaticus, seizures Neoplastic – Esophageal carcinoma, usually after instrumentation or biopsy

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Cervical EP: Acute onset dysphagia, neck pain, fever ○ Thoracic EP: Sudden onset of excruciating substernal or lower thoracic chest pain ○ Rapid onset of overwhelming sepsis, fever, tachycardia, hypotension, shock ○ Dysphagia, increased oral secretions, respiratory distress soon after endoscopy ○ Atypical chest pain, referred to shoulder or back; epigastric pain • Other signs/symptoms ○ Presence of "signal" hemorrhage from gastrointestinal (GI) tract; vascular trauma due to perforating object ○ Severe mediastinitis if food, saliva, refluxed peptic acid enter mediastinum • Clinical diagnosis may be mistaken (e.g., for angina) • Diagnosis by contrast esophagography: 90% are positive

Demographics • Age ○ Any age; infants, children, and elderly are most affected • Epidemiology ○ Incidence of EP as endoscopic procedures become more frequent

Natural History & Prognosis • Most serious and rapidly fatal type of perforation in GI tract • Life-threatening: High morbidity, high mortality without intervention • Underlying esophageal disease, diverticulum, cervical lordosis, osteophytes: risk

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• Can be immediate or delayed for several days if due to dilation procedures • Complications: Retropharyngeal abscess, sepsis, shock ○ Mediastinitis, mediastinal abscess, pericarditis, pneumothorax, fistula (thoracic EP) • Prognosis dependent on cause, location, and type of underlying esophageal disease • Prognosis directly related to interval between perforation and intervention ○ After 24 hours: 70% mortality rate (thoracic EP) ○ If untreated, mortality rate nearly 100% for thoracic EP • Better prognosis with cervical EP than thoracic ○ Cervical: 15% mortality ○ Thoracic: 25% mortality

Treatment • Conservative: Parenteral fluids, antibiotics ○ Limited esophageal injuries meeting proper selection criteria ○ Small cervical EP ○ Rarely, thoracic EP heals spontaneously without surgical intervention – Especially if intramural or very localized • Surgical ○ Cervical esophageal perforation (EP): Cervical mediastinotomy, open drainage ○ Thoracic EP: Immediate thoracotomy, primary closure of EP, mediastinal drainage • Covered metallic stents for leaks and fistulas ○ Growing in use ○ May still require drain placement in mediastinum ± pleural space • Nonsurgical interventional drainage techniques; transesophageal drainage of abscesses

DIAGNOSTIC CHECKLIST Consider • Clinical and radiographic signs of EP may be subtle ○ Active investigation is needed to establish diagnosis

Image Interpretation Pearls • Esophagram: Rapid sequence filming in multiple obliquities • Esophagography and CT are complementary; either can "miss" perforation

SELECTED REFERENCES 1. 2. 3. 4.

Dent B et al: Minimally invasive endoscopic therapy for the management of Boerhaave's syndrome. Ann R Coll Surg Engl. 96(3):253-4, 2014 Freeman RK et al: Esophageal stent placement for the treatment of spontaneous esophageal perforations. Ann Thorac Surg. 88(1):194-8, 2009 Buecker A et al: Esophageal perforation: comparison of use of aqueous and barium-containing contrast media. Radiology. 202(3):683-6, 1997 Hoover EL: The diagnosis and management of esophageal perforations. J Natl Med Assoc. 83(3):246-8, 1991

Esophageal Perforation Esophagus

(Left) Esophagram in a 54year-old man with esophageal cancer and chest pain following endoscopic biopsy demonstrates a long, irregular, eccentric stricture of the distal esophagus , characteristic of carcinoma. Focal extravasation of contrast indicates perforation. (Right) Film from an esophagram in a 67-year-old man with chest pain following repair of an epiphrenic diverticulum shows a persistent, linear, focal collection of contrast medium , representing a small leak. This healed with antibiotic therapy alone.

(Left) Esophagram film in a patient with neck and chest pain following attempted placement of a feeding tube shows a retroesophageal (mediastinal) collection of gas and water-soluble contrast medium . This resulted from perforation of a Zenker diverticulum by the feeding tube. The track runs posterior and parallel to the course of the proximal esophagus. (Right) Axial NECT in the same patient shows subcutaneous gas , extraluminal gas, and contrast medium in the prevertebral region .

(Left) Esophagram in a 58year-old man with chest pain following endoscopic removal of an impacted food bolus shows perforation of the distal esophagus with extravasation of contrast material and gas into the upper abdomen and mediastinum and free air under the diaphragm. (Right) Axial NECT in the same patient shows free intraperitoneal gas and extraluminal gas along the esophagus and proximal stomach . The imaging findings are identical to those seen in Boerhaave syndrome.

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Esophagus

Boerhaave Syndrome KEY FACTS

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Sudden increase in intraluminal pressure leads to fullthickness esophageal perforation ○ Usually from left side of distal thoracic esophagus • Chest film ○ Left side pleural effusion or hydropneumothorax ○ Radiolucent streaks of gas along aorta or in neck • Esophagography with nonionic, water-soluble contrast agent ○ Shows extravasation of ingested or injected (through nasogastric tube) contrast medium ○ From left side of esophagus, just above gastroesophageal (GE) junction ○ If initial study with water-soluble contrast medium fails to show leak, examination must be repeated immediately with barium to detect subtle leaks • CT ○ Extraluminal gas &/or oral contrast medium in lower mediastinum &/or upper abdomen

• Mallory-Weiss syndrome • Pulsion diverticulum (epiphrenic) • Iatrogenic (postinstrumentation) injury

(Left) Graphic shows a vertically oriented laceration of the distal esophagus, just above the hiatus and gastroesophageal (GE) junction. (Right) Film from an esophagram following injection of a water-soluble contrast medium through a nasogastric tube demonstrates a leak of contrast medium from a tear in the left anterior wall of the distal esophagus , a classic appearance for Boerhaave syndrome.

(Left) Axial CECT in a middleaged man with severe chest pain after repeated retching shows extraluminal gas and contrast material surrounding the esophagus in the lower mediastinum and upper abdomen. (Right) Film from a fluoroscopic exam in the same patient during injection of water-soluble contrast through a nasogastric tube shows extraluminal contrast in the mediastinum and upper abdomen . The site of the tear is the left anterior wall of the distal esophagus.

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CLINICAL ISSUES • Accounts for 15% of total esophageal perforation cases • Prognosis for large perforation ○ After 24 hours without treatment: Mortality = 70% ○ After immediate surgical drainage: Good • Treatment ○ Drains in esophagus, mediastinum, pleural space, &/or abdomen

Boerhaave Syndrome

Definitions • Spontaneous distal esophageal perforation following vomiting or other violent straining

IMAGING General Features • Best diagnostic clue ○ Extraluminal gas and contrast material in lower mediastinum surrounding esophagus • Other general features ○ Sudden increase in intraluminal pressure leads to fullthickness esophageal perforation ○ Left side of distal thoracic esophagus – Vertical, full-thickness tear, 1-4 cm long ○ Rarely from cervical or upper thoracic esophagus – Mortality rate < 15% if treated promptly

Radiographic Findings • Radiography ○ Chest radiograph – Mediastinal widening, pneumomediastinum – Left-side pleural effusion or hydropneumothorax – Radiolucent streaks of gas along aorta or in neck ○ Abdominal radiograph – Gas in retroperitoneum or intraperitoneal (rare) ○ Esophagography – Shows extravasation of ingested or injected (through nasogastric [NG] tube) contrast medium – From left side of esophagus, just above gastroesophageal (GE) junction

CT Findings • Extraluminal gas &/or oral contrast medium in lower mediastinum &/or upper abdomen • Periesophageal, pleural, pericardial fluid collections

Imaging Recommendations • Plain chest radiograph; helical CECT with oral contrast • Esophagography with nonionic water-soluble contrast agent ○ If initial study with water-soluble contrast medium fails to show leak, examination must be repeated immediately with barium to detect subtle leaks

DIFFERENTIAL DIAGNOSIS Mallory-Weiss Syndrome • Irregular linear mucosal tear or laceration in long axis of esophagus ○ Distal esophagus near GE junction or gastric cardia ○ Rarely detected on imaging studies

• Location: Cervical (common), thoracic esophagus • Indistinguishable from Boerhaave syndrome if distal esophagus is involved

PATHOLOGY General Features • Etiology ○ Rare causes – Coughing, weightlifting, childbirth, defecation – Seizures, status asthmaticus, blunt trauma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Classic triad – Vomiting, severe substernal chest pain – Subcutaneous emphysema of chest wall and neck ○ Rapid onset of overwhelming sepsis – Fever, tachycardia, in blood pressure, shock • Clinical profile ○ Patient with history of chronic alcoholism, severe vomiting, sudden severe substernal chest pain, and in blood pressure

Demographics • Age ○ Usually adults

Natural History & Prognosis • Prognosis ○ Large perforation – After 24 hours without treatment: Mortality = 70% – After immediate surgical drainage: Good

Treatment • Large perforation ○ Immediate thoracotomy or thoracoscopy ○ Drains in esophagus, mediastinum, pleural space, &/or abdomen • Small, self-contained perforation ○ Managed nonoperatively with broad spectrum antibiotics and parenteral alimentation

DIAGNOSTIC CHECKLIST Consider • Check for history of violent retching or vomiting

SELECTED REFERENCES 1.

2.

Pulsion Diverticulum (Epiphrenic) • Mucosa-lined pouch from distal esophagus • No free mediastinal gas or inflammation

Esophagus

TERMINOLOGY

3.

Dasari BV et al: The role of esophageal stents in the management of esophageal anastomotic leaks and benign esophageal perforations. Ann Surg. 259(5):852-60, 2014 Biancari F et al: Current treatment and outcome of esophageal perforations in adults: systematic review and meta-analysis of 75 studies. World J Surg. 37(5):1051-9, 2013 de Schipper JP et al: Spontaneous rupture of the oesophagus: Boerhaave's syndrome in 2008. Literature review and treatment algorithm. Dig Surg. 26(1):1-6, 2009

Iatrogenic (Postinstrumentation) Injury • Endoscopic procedures account for 75% of cases ○ Feeding or NG tubes can also perforate esophagus or esophageal diverticulum 217

Esophagus

Esophagectomy: Ivor Lewis and Other Procedures KEY FACTS

TERMINOLOGY • Surgical resection of a portion of esophagus and replacement by a conduit formed by another portion of alimentary tube

IMAGING • Many surgical options for surgical excision of esophagus ○ Transthoracic esophagectomy: Usually performed through right intercostal approach (Ivor Lewis procedure) ○ Other options include minimally invasive (laparoscopic) procedures • Stomach is ideal conduit, as it has reliable blood supply and can reach high into thorax or neck for anastomosis ○ Esophagogastric anastomosis is created high in thorax, above level of azygous arch • Perioperative complications ○ Hemorrhage ○ Injury to recurrent laryngeal or vagus nerve (5-10%)

(Left) Graphic illustrates the 1st step in an esophagectomy with gastric interposition. The stomach is divided along its long axis, creating a gastric tube or conduit 5 or 6 cm in diameter, which is pulled up into the chest. This can be done through a right (Ivor Lewis) or left thoracotomy or even through laparoscopic ports. A pyloroplasty is done to facilitate gastric emptying. (Right) Graphic shows the gastric conduit anastomosed to the mid esophagus and the pyloroplasty .

(Left) Graphic shows the gastric conduit anastomosed to the cervical esophagus. Note the position of the gastric staple line along the right side of the conduit. (Right) Axial CT shows a mildly dilated, gasfilled gastric conduit in the paravertebral location. Note the position of the gastric staple line . The conduit is not filled with retained fluid, and there is no evidence of lung injury from reflux.

218

○ Injury to tracheobronchial tree ○ Chylothorax (2-4%) • Postoperative complications ○ Essentially all patients have some degree of dysphagia, early satiety, and reflux following esophagectomy ○ Anastomotic leak (10-16%) ○ Anastomotic stricture (15-25%) ○ Diaphragmatic hernia (1-6%) ○ Delayed emptying of conduit – Causes: Redundant conduit (excess length of gastric tube), mechanical obstruction, twisted conduit, functional delay ○ Recurrent carcinoma • Complication rates vary substantially according to experience and skill of surgical team ○ Open surgical procedures tend to result in higher perioperative morbidity and mortality ○ High (cervical) anastomoses result in slightly higher incidence of injury to laryngeal nerve

Esophagectomy: Ivor Lewis and Other Procedures

Definitions • Surgical resection of portion of esophagus and replacement by conduit formed by another portion of alimentary tube

IMAGING Surgical Procedures • Usual indication for surgery ○ Curative or palliative resection of esophageal carcinoma ○ Resection of Barrett esophagus with severe dysplasia • Many surgical options for surgical excision of portion of esophagus • Transthoracic esophagectomy ○ Usually performed through right intercostal approach (Ivor Lewis procedure) – Generally begins with laparotomy for mobilization of stomach, which is then used to create gastric tube/conduit that will replace resected esophagus □ Either entire stomach or tubularized portion (divided along long axis) is used □ Stomach is ideal conduit, as it has reliable blood supply and can reach high into thorax or neck for anastomosis – As part of laparotomy, upper abdominal lymph nodes (celiac, gastrohepatic) are resected – Pyloroplasty or pyloromyotomy is performed to facilitate gastric emptying and to minimize gastroesophageal reflux – At thoracotomy, esophagus and thoracic duct are dissected from vertebral column – Esophagus and regional lymph nodes (mediastinum and neck) are resected en bloc – Esophagogastric anastomosis is created in thorax, above level of tracheal carina □ Some surgeons make anastomosis in lower neck – Gastric conduit is usually placed in pre- or paravertebral space of posterior mediastinum □ Less commonly in retrosternal, intrapleural, or subcutaneous position – Colon and jejunum are used much less commonly to bypass or replace resected (or obstructed) esophagus □ Usually after failed gastric interposition ○ Many variations exist – e.g., left thoracotomy approach, transhiatal open approach (without thoracotomy), minimally invasive procedures (performed through ports in thorax and abdomen without open incision into either) – Surgical approach may be affected by patient condition (site and depth of tumor, mediastinal scarring from prior surgery, etc.) – Experience and preference of surgeon play larger role in surgical approach ○ Complication rates – No proof of significantly different morbidity or mortality among various surgical approaches □ Complication rates vary substantially according to experience and skill of surgical team

– Open surgical procedures tend to result in slightly higher perioperative morbidity and mortality – High (cervical) anastomoses result in slightly higher incidence of injury to laryngeal nerve ○ Contraindications to esophagectomy (relative or absolute) – Tumor invasion of trachea or aorta – Extensive mediastinal scarring, e.g., from prior perforation, surgery, radiation therapy

Esophagus

TERMINOLOGY

Complications • Perioperative complications ○ Hemorrhage – Can be substantial problem during dissection and removal of esophagus ○ Injury to recurrent laryngeal or vagus nerve (5-10%) – Mediastinal and lower cervical nodes lie close to vagus and recurrent laryngeal nerves □ Nerves may be damaged during lymph node resection – Results in impaired cough and increased risk of aspiration pneumonia ○ Injury to tracheobronchial tree – Esophageal tumor may invade tracheobronchial tree; attempts to separate tumor may damage bronchus – Can result in fistula, aspiration pneumonia ○ Chylothorax (2-4%) – Thoracic duct may be damaged or transected during surgery – Can result in persistent chylothorax • Postoperative complications ○ Essentially all patients have some degree of dysphagia, early satiety, and reflux following esophagectomy – Most patients learn to cope with these symptoms, which may decrease over time – Many complications are treated medically, and some respond to minimally invasive interventions – Mortality □ 30-day mortality (6-10%) □ 5-year mortality (70-80%) ○ Nonspecific complications – Respiratory complications (~ 25%) – Cardiovascular complications (10-15%) – Wound infections (5-10%) – Chylothorax (2-5%) ○ Anastomotic leak (10-16%) – Early complication, usually detected within days of surgery – Occurs more commonly with neck anastomoses, but thoracic anastomotic leaks cause more serious complications – Some may respond to conservative management (controlled by surgical drains left in place) – Accessible, loculated leaks may be treated by placing percutaneous drainage catheter □ Larger, uncontained leaks usually require surgical revision of anastomosis – Usually leads to abscess in mediastinum &/or pleural space ○ Anastomotic stricture (15-25%) – Early or late complication 219

Esophagus

Esophagectomy: Ivor Lewis and Other Procedures

– Most due to benign, probably ischemic, stricture □ Irregular, long stricture raises concern for recurrent malignancy in esophagus or mediastinum – Diagnosed by barium esophagram with delayed passage, air-fluid level, dilation of esophagus – Usually responds to balloon dilation (may require repeated treatments) ○ Diaphragmatic hernia (1-6%) – Omental fat &/or colon may herniate into chest behind gastric conduit – Usually requires surgical revision but may recur ○ Delayed emptying of conduit – Very substantial problem leading to significant symptoms in 25-30% of patients □ Places patient at increased risk of regurgitation and aspiration; impairs nutrition □ Severe enough to require surgical revision in 1-5% of cases; skill and experience of surgeon affects prevalence of this complication – Redundant conduit (excess length of gastric tube) □ Results in horizontal portion of conduit above diaphragm that impairs emptying □ Looks and behaves like end-stage achalasia □ Treated by surgical revision (pulling excess conduit back into abdomen) – Mechanical obstruction □ At hiatus (too small or tight for gastric conduit): Some degree of narrowing of gastric conduit through diaphragm is expected □ At pylorus: Should be obviated by pyloroplasty – Twisted conduit □ Gastric suture line along resected lesser curve should appear at 9-o'clock position □ Rotation > 90° indicates twist or volvulus of conduit □ May require surgical revision – Functional delay □ Conduit is not very dilated or mechanically obstructed but is slow to empty □ May be due to vagotomy or injury to vagus nerve □ Resection of lesser curve of stomach causes loss of gastric pacemaker neurons ○ Recurrent carcinoma – Majority of patients treated for esophageal carcinoma with esophagectomy will die of recurrent or metastatic disease □ 5-year mortality exceeds 75% (varies according to aggressiveness of surgeon in operating on patients with early or advanced cancer)

Imaging Recommendations • Protocol advice ○ Esophagram – Often performed within 1st few days of surgery □ To assess for anastomotic leak or redundant conduit within chest – 1st study is performed with water-soluble contrast medium, preferably nonionic, low osmolar □ Reduce danger of aspiration pneumonitis from hyperosmolar contrast medium □ Reduce danger of mediastinal or peritoneal inflammation from extravasated barium 220

– Subsequent exams are performed with ingestion of barium □ Evaluate anastomosis for stricture □ Evaluate degree of distention and rate of emptying of gastric conduit ○ CECT – Complementary role to esophagram – Assessment of anastomotic leak, thoracic complications (mediastinitis, pleural effusion, etc.) ○ PET/CT – Best test for detection of recurrent carcinoma □ Usually apparent as FDG-avid sites – Uncommonly occurs within esophagus or gastric conduit – Pleural or peritoneal seeding are more common – Hematogenous metastases to liver, lungs, bones, and other sites

CLINICAL ISSUES Natural History & Prognosis • Perioperative mortality of 5-10% ○ > 75% of patients will die within 5 years • Almost all patients have symptoms of reflux, early satiety, and dysphagia ○ > 5% will have 1 or more complications that require surgery or intervention • In spite of problems, modern surgical techniques for esophagectomy offer significant improvement in morbidity and mortality compared with earlier treatment options

SELECTED REFERENCES 1.

2. 3.

4.

5. 6. 7. 8. 9.

Alldinger I et al: Endoscopic treatment of anastomotic leakage after esophagectomy or gastrectomy for carcinoma with self-expanding removable stents. Hepatogastroenterology. 61(129):111-4, 2014 Kent MS et al: Revisional surgery after esophagectomy: an analysis of 43 patients. Ann Thorac Surg. 86(3):975-83; discussion 967-74, 2008 Wolff CS et al: Ivor Lewis approach is superior to transhiatal approach in retrieval of lymph nodes at esophagectomy. Dis Esophagus. 21(4):328-33, 2008 Chen G et al: Recurrence pattern of squamous cell carcinoma in the middle thoracic esophagus after modified Ivor-Lewis esophagectomy. World J Surg. 31(5):1107-14, 2007 Kim TJ et al: Postoperative imaging of esophageal cancer: what chest radiologists need to know. Radiographics. 27(2):409-29, 2007 Bizekis C et al: Initial experience with minimally invasive Ivor Lewis esophagectomy. Ann Thorac Surg. 82(2):402-6; discussion 406-7, 2006 de Hoyos A et al: Minimally invasive esophagectomy. Surg Clin North Am. 85(3):631-47, 2005 Gilbert S et al: Minimally invasive esophagectomy. Adv Surg. 38:67-83, 2004 Luketich JD et al: Minimally invasive resection and mechanical cervical esophagogastric anastomotic techniques in the management of esophageal cancer. J Gastrointest Surg. 8(8):927-9, 2004

Esophagectomy: Ivor Lewis and Other Procedures Esophagus

(Left) Axial CECT in a 65-yearold man postesophagectomy shows the fluid-distended gastric conduit and evidence of severe aspiration pneumonia and pleural effusion. The conduit is probably twisted, as evidenced by the position of the gastric staple line . (Right) Axial CECT in the same patient shows impaired emptying and fluid distention of the gastric conduit , as well as severe lung disease and pleural effusions.

(Left) Esophagram film of a redundant conduit with delayed emptying shows marked distention of the gastric conduit with a horizontal component above the diaphragmatic hiatus. Note the similarity to endstage achalasia. (Right) Esophagram shows kinking of the redundant conduit above the diaphragm . The conduit is dilated with an airfluid level, indicating partial obstruction. The conduit was pulled down into the abdomen at revision laparoscopy with resolution of symptoms.

(Left) Graphic shows a redundant conduit with distention and delayed emptying. The horizontal portion of the conduit contributes to the impaired gastric emptying. Note that the point of narrowing is at the diaphragm , not the pylorus, which has been widened by pyloroplasty . (Right) Note the point of narrowing , which is proximal to the collapsed gastric antrum in this patient with mechanical obstruction of the conduit at the diaphragmatic hiatus (the most common site).

221

Esophagus

Esophagectomy: Ivor Lewis and Other Procedures

(Left) Film from an esophagram in a patient with obstruction shows a dilated conduit with air-fluid-barium levels . The stomach is narrowed as it traverses the diaphragm , but the pyloroplasty is neither the site nor the cause of the delayed emptying. (Right) Esophagram in a patient with functional delayed emptying shows only mild dilation of the gastric conduit and no mechanical deformity. Slow emptying is seen as air-fluidbarium levels on upright film. Vagal nerve injury is the most common etiology.

(Left) Graphic shows herniation of transverse colon through the diaphragmatic hiatus between the conduit and the left crus, the most common location for a diaphragmatic hernia. (Right) Axial CECT shows herniation of the transverse colon and omental fat posterior to the gastric conduit .

(Left) Graphic shows a twisted conduit. Note the position of the gastric staple line , which has rotated to the left anterolateral position. (Right) In the same patient, NECT shows a dilated gastric conduit , suggesting impaired emptying. The position of the gastric staple line indicates rotation or volvulus of the conduit, as it is expected to be at the 9-o' clock position

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Esophagectomy: Ivor Lewis and Other Procedures Esophagus

(Left) Film from an esophagram shows a tight stricture at the esophagogastric anastomosis with delayed emptying of the esophagus, evident as an airfluid level. Note the smooth surface of the esophagus and the rugal fold pattern of the gastric conduit . (Right) Spot film from an esophagram in a 70-year-old man with fever and chest pain 3 days after partial esophagectomy shows the anastomosis between the esophagus and the gastric conduit . There is an anastomotic leak into the mediastinum.

(Left) Coronal reformatted NECT in the same patient shows oral contrast medium within the gastric conduit . (Right) Another NECT section in the same patient shows contrast extravasation from the esophagogastric anastomosis into the mediastinum.

(Left) Axial CECT 18 months after esophagectomy shows the nondilated gastric conduit . There is a large soft tissue mass abutting the conduit and extending into the mediastinum in this patient with a recurrent tumor. (Right) Coronal reformation of CECT in the same patient shows the gastric conduit and extensive mediastinal mass effect , representing recurrent esophageal tumor. A portion of the anastomotic staple line is seen.

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Esophagus

Intramural Benign Esophageal Tumors KEY FACTS

• Types include leiomyoma, GI stromal tumor, granular cell, lipoma, hemangioma, hamartoma • Fluoroscopic-guided barium studies ○ Discrete mass; solitary (most common) or multiple ○ Round or ovoid filling defects sharply outlined by barium on each side (en face view) ○ Narrowed (tangential view) or stretched and widened (en face view) esophageal lumen ○ Smooth surface lesion, with upper and lower borders of lesion forming right or slightly obtuse angles with adjacent esophageal wall (profile view) ○ Overlying mucosa may ulcerate • Leiomyoma: ± amorphous or punctate calcifications • Esophageal gastrointestinal stromal tumor (GIST) ○ May be large mass ○ May ulcerate with gas ± contrast medium entering cavity • CT: Discrete mass in wall; no signs of invasion or metastases

(Left) Film from a barium esophagram demonstrates a mass causing eccentric narrowing of the distal lumen. The mass forms obtuse angles with the wall, and the esophageal folds and mucosa are intact. A leiomyoma was enucleated endoscopically. (Right) Single-contrast esophagram shows an en face view of an intramural mass in the distal esophagus with central ulceration due to leiomyoma. The traction diverticulum is an incidental finding.

(Left) Coronal CECT in a 24year-old man shows a huge, soft tissue density mass that envelops and displaces the distal esophagus . Small foci of calcification are noted. The mass was resected and proved to be a benign leiomyoma arising from the esophageal wall. (Right) Axial CECT in a 73-year-old woman shows a huge esophageal mass with a large central ulceration that contains gas due to communication with the esophageal lumen. The central cavitation is typical of a GIST; the esophagus is an unusual site.

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○ Helps distinguish lipoma (fat density) and other mediastinal masses (e.g., mediastinal cyst)

IMAGING

TOP DIFFERENTIAL DIAGNOSES • • • •

Mediastinal tumor Normal mediastinal structures Esophageal carcinoma Foreign body

CLINICAL ISSUES • Asymptomatic: No treatment • Large, symptomatic lesions: Enucleation or esophageal resection with gastric interposition

DIAGNOSTIC CHECKLIST • Most intramural masses are benign (unlike gastric tumors) • Leiomyomas are much more common than GIST in esophagus (but not in stomach) • Calcifications suggest leiomyoma; almost never occur in other benign/malignant esophageal tumors

Intramural Benign Esophageal Tumors

PATHOLOGY

Definitions

Gross Pathologic & Surgical Features

• Benign mass composed of 1 or more tissue elements of esophageal wall

• Leiomyoma: Firm, round, tan, unencapsulated • GIST: Firm, tan mass, often with central necrosis, mucosal ulceration • Granular cell: Broad-based, pinkish-tan mass with normal overlying mucosa and rubbery consistency • Lipoma: Smooth, yellow, encapsulated tumor composed of well-differentiated adipose tissue • Hemangioma: Blue to red, nodular mass • Hamartoma: Various elements, including cartilage, bone, adipose and fibrous tissue, and muscle • Mediastinal foregut cyst ○ Thin-walled, nonenhancing contents ○ Contents are water density (50%) to calcific

IMAGING General Features • Best diagnostic clue ○ Intramural mass with smooth surface and slightly obtuse borders on barium esophagram • Size ○ 1 cm to > 10 cm • Other ○ Types include leiomyoma, GI stromal tumor, granular cell, lipoma, hemangioma, hamartoma

Radiographic Findings • Fluoroscopic-guided barium studies ○ Discrete mass; solitary (most common) or multiple ○ Round or ovoid filling defects sharply outlined by barium on each side (en face view) – Overlying mucosa may ulcerate ○ Smooth surface lesion, with upper and lower borders forming right or slightly obtuse angles with adjacent esophageal wall (profile view) ○ Narrowed (tangential view) or stretched and widened (en face view) esophageal lumen – Varying degree of obstruction ○ Leiomyoma ± amorphous or punctate calcifications ○ Esophageal gastrointestinal stromal tumor (GIST) – May be large mass – May ulcerate with gas ± contrast medium entering cavity

Microscopic Features • GIST distinguished from leiomyoma by evidence of CD117 (C-kit) activity

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic (most common) or dysphagia

Demographics • Age ○ > 40 years old • Gender ○ Leiomyoma: M:F = 2:1 • Epidemiology ○ Leiomyomas are much more common than GIST or other intramural esophageal tumors

CT Findings

Natural History & Prognosis

• Discrete mass in wall; no signs of invasion or metastases • Helps distinguish lipoma (fat density) and other mediastinal masses (e.g., mediastinal cyst)

• Complications: Hemorrhage, obstruction, ulceration • Prognosis: Very good

Imaging Recommendations

• Asymptomatic: No treatment • Large, symptomatic lesions ○ Enucleation or esophageal resection with gastric interposition

• Best imaging tool ○ Barium studies followed by CT for large mass

DIFFERENTIAL DIAGNOSIS Mediastinal Tumor • Compresses or indents esophagus with obtuse margins • CT better shows extent, origin, and nature of mass

Normal Mediastinal Structures • Indentation by aorta, left main bronchus, aberrant or dilated vessels

Esophageal Carcinoma • "Apple core" or eccentric mucosal mass

Esophagus

TERMINOLOGY

Treatment

DIAGNOSTIC CHECKLIST Consider • Barium esophagram and CT are complementary • Most intramural masses are benign (unlike gastric tumors)

Image Interpretation Pearls • Calcifications suggest leiomyoma; almost never occur in other esophageal tumors

SELECTED REFERENCES

Foreign Body

1.

• Intraluminal mass, often above stricture

2.

Shin S et al: Enucleation of esophageal submucosal tumors: a single institution's experience. Ann Thorac Surg. 97(2):454-9, 2014 Levine MS: Benign tumors of the esophagus: radiologic evaluation. Semin Thorac Cardiovasc Surg. 15(1):9-19, 2003

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Esophagus

Fibrovascular Polyp KEY FACTS

TERMINOLOGY • Rare, benign, tumor-like lesion of esophagus ○ Originates within esophageal wall but presents as intraluminal polyp or mass

IMAGING • Fluoroscopic-guided esophagography ○ Smooth, expansile, sausage-shaped, and intraluminal ○ Cervical esophageal mass, extending distally to fill esophageal lumen • CT: Varied density based on content ○ Fat density: Abundance of adipose tissue ○ Heterogeneous: Mixture of fat, soft tissue

TOP DIFFERENTIAL DIAGNOSES • Esophageal carcinoma ○ May present as large, polypoid intraluminal mass ○ Margins are irregular and more lobulated • Esophageal intramural benign tumors

(Left) Graphic shows a long, smooth, sausage-like mass arising from the proximal esophageal wall, filling most of the esophageal lumen. (Right) Barium esophagram demonstrates a large, cylindrical mass in the esophagus. The mass originates from a pedicle near the cricopharyngeal level. The mass is so long and bulky that it might be mistaken for an air bubble or debris within the esophagus.

(Left) Barium esophagram demonstrates a huge, lobulated, polypoid filling defect within the esophagus, extending the entire length of the esophagus. The mass is not readily seen within the proximal esophagus, but it distends the lumen. (Right) Axial CECT in the same patient shows the mass as a mixed soft tissue and fat density lesion within the grossly distended esophagus.

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○ Leiomyoma and lipoma ○ Rarely as large or long as fibrovascular polyps

PATHOLOGY • Giant, smooth or lobulated, expansile polyp with discrete pedicle attached to cervical esophagus • Varying amounts of fibrovascular and adipose tissue covered by normal squamous epithelium

CLINICAL ISSUES • Uncommonly, regurgitation of mass into pharynx or mouth ○ May cause laryngeal occlusion, asphyxia, and sudden death • Fibrovascular polyps may bleed • Malignant degeneration extremely rare • Treatment ○ Small fibrovascular polyps: Endoscopic resection ○ Gigantic fibrovascular polyps: Surgical resection

Esophageal Inflammatory Polyp

TERMINOLOGY

PATHOLOGY

• Synonym: Inflammatory fibroid polyp • Definition: Reactive inflammatory polypoid lesion of distal esophagus

• Nonencapsulated submucosal lesion ○ Composed of loose connective tissue and vessels, granulation tissue, and eosinophilic inflammatory component • Etiology ○ Inflammatory response to repetitive chemical or physical trauma ○ Most cases are due to gastroesophageal reflux disease (GERD) • No malignant potential

IMAGING • Barium esophagram is imaging procedure of choice • Best clue ○ Smooth, ovoid protuberance and "sentinel fold" on barium esophagram in patient with history of acid reflux disease – Uncommonly, may have irregular border or lobulation – Represents bulbous tip of prominent gastric fold extending from gastric cardia into distal esophagus – Located at or above gastroesophageal (GE) junction – 5-20 mm in size • Endoscopic ultrasound ○ Round, hypoechoic lesion within 2nd and 3rd layers of esophageal wall ○ Homogeneous echogenicity, richly vascularized

TOP DIFFERENTIAL DIAGNOSES • Esophageal intramural benign tumors ○ Hypoechoic with heterogeneous echogenicity on endoscopic US ○ Arising from muscularis propria layer ○ Usually have obtuse margin with esophageal wall on esophagram • Thrombosed esophageal varix ○ History of portal hypertension and associated findings (cirrhosis, ascites, etc.) ○ Usually have history of iatrogenic sclerosis (by injecting varices) • Esophageal papilloma ○ Usually isolated, small, sessile mass ○ More common in lower 1/3 of esophagus ○ Usually asymptomatic

Esophagus

KEY FACTS

CLINICAL ISSUES • Associated findings or conditions ○ GERD ○ Esophagitis ○ Hiatal hernia • Presenting symptoms ○ Epigastric pain ○ Acid reflux ○ Dyspepsia ○ Dysphagia ○ Bleeding (uncommon) • Diagnosis ○ No biopsy needed for typical lesions ○ Esophagoscopy and biopsy if atypical appearance • Prevalence: Rare • Natural history ○ No malignant potential ○ May resolve with treatment for GERD

(Left) Graphic shows a small hiatal hernia with thickened, inflamed esophageal and gastric folds. A polypoid thickening of one of these folds is seen as an inflammatory polyp . (Right) Spot film from an esophagram shows a thickened fold with a nodular, polypoid extension arising from the esophagogastric junction. The polyp is continuous with thickened folds, which extend into the gastric fundus.

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Esophagus

Esophageal Carcinoma KEY FACTS

IMAGING • Squamous cell carcinoma (SCC) ○ 2 major risk factors in USA: Tobacco and alcohol abuse • Adenocarcinoma ○ 90-100% of cases arise from Barrett mucosa ○ Increasing in prevalence relative to SCC, especially in USA • Double-contrast esophagography ○ Best for detection of early cancer ○ Usually sessile polyp or flattening of esophageal wall • Advanced cancer ○ Luminal constriction (stricture) with nodular or ulcerated mucosa ○ Polypoid, ulcerative, varicoid, irregular constricting forms • CT: Useful for staging ○ Mediastinal and abdominal lymphadenopathy ○ Liver and other metastases • PET/CT: Superior to CT in detecting regional and distant metastases

(Left) Graphic shows a sessile polypoid mass with an irregular surface that infiltrates the esophageal wall and narrows the lumen, a typical appearance of an esophageal carcinoma. (Right) Spot film from an esophagram shows a polypoid mass of the distal esophagus with an irregular surface and luminal narrowing. This was a squamous cell carcinoma.

(Left) The initial 2 films from a barium esophagram (not shown) looked normal. However, a repeat film, with emphasis on suspended deep inspiration and Valsalva maneuver, demonstrates nodular thickened folds in the distal esophagus. (Right) Another spot film in the same patient with deep inspiration and Valsalva demonstrates nodular thickened folds and luminal narrowing in the distal esophagus. Biopsy confirmed adenocarcinoma.

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• Endoscopic ultrasonography (EUS) ○ Best technique for determining locoregional extent of tumor

TOP DIFFERENTIAL DIAGNOSES • • • • •

Reflux esophagitis (with stricture) Esophageal intramural benign tumors Esophageal metastases and lymphoma Radiation esophagitis Foreign body, esophagus

CLINICAL ISSUES • Dramatic change from squamous cell to adenocarcinoma prevalence in USA within past 20 years • Early cancer: 5-year survival = 90% • Treatment ○ Surgery, radiation (pre- and postoperative radiation) ○ Esophagectomy with gastric interposition is most common

Esophageal Carcinoma

Definitions • Squamous cell carcinoma (SCC): Malignant transformation of squamous epithelium • Adenocarcinoma: Malignant dysplasia in columnar metaplasia (Barrett mucosa)

IMAGING General Features • Best diagnostic clue ○ Fixed irregular narrowing of esophageal lumen with destroyed mucosal pattern • Location ○ Middle 1/3 (50%), lower 1/3 (30%), upper 1/3 (20%) • Morphology ○ Classification of advanced esophageal cancer based on gross pathology and radiographic findings – Infiltrating, polypoid, ulcerative, varicoid lesions • Other general features ○ Carcinoma is most common tumor of esophagus (> 95%) ○ Squamous cell cancer (SCC) – Accounts for about 40% of esophageal cancer in USA and 90% in developing countries □ Decreasing in relative prevalence as adenocarcinoma becomes more common – Human papillomavirus: Synergistic increased risk factor □ Especially in China and South Africa – 1% of all cancers and 7% of all gastrointestinal cancers – 2 major risk factors in USA: Tobacco and alcohol abuse ○ Adenocarcinoma – Accounts for > 60% of esophageal cancer in USA – Increasing in prevalence relative to SCC – 90-100% of cases arise from Barrett mucosa

Radiographic Findings • Double-contrast esophagography: En face and profile views ○ Early esophageal squamous cell cancer – Plaque-like lesions: Small, sessile polyps, or depressed lesions ○ Early adenocarcinoma in Barrett esophagus – Plaque-like lesions: Flat, sessile polyps – Localized area of flattening/stiffening in wall of peptic stricture (common in distal 1/3) ○ Advanced esophageal squamous cell cancer – Infiltrating lesion (most common): Irregular narrowing, luminal constriction (stricture) with nodular or ulcerated mucosa – Polypoid lesion: Lobulated, fungating intraluminal mass – Ulcerative lesion: Well-defined meniscoid ulcers with radiolucent rim of tumor surrounding ulcer in profile view – Varicoid lesion: Thickened, tortuous, serpiginous longitudinal folds due to submucosal spread of tumor, mimicking varices □ Key difference: No change on repeated films ○ Advanced adenocarcinoma in Barrett esophagus – Radiologically indistinguishable from SCC

Esophagus

– Long infiltrating lesion in distal esophagus ○ Stricture in advanced carcinoma – Asymmetric contour with abrupt proximal borders of narrowed distal segment ("rat-tail" appearance)

TERMINOLOGY

CT Findings • CT: Staging of esophageal carcinoma ○ Stages I and II: Localized wall thickening or small luminal tumor, without mediastinal invasion ○ Stage III: Tumor extends beyond esophagus into mediastinal tissues – Tracheobronchial invasion: Posterior wall indentation/bowing and tracheobronchial displacement/compression; ± collapse of lobes – Aortic invasion: Uncommon finding (2% of cases) – Pericardial invasion: Based on obliteration of fat plane or mass effect – Mediastinal adenopathy: Discrete or confluent with primary tumor ○ Stage IV: Extends into mediastinum and distant sites – Liver, lungs, pleura, adrenals, kidneys, and nodes – Subdiaphragmatic adenopathy seen in > 2/3 of distal cancers

MR Findings • Provides similar information as CT

Ultrasonographic Findings • Grayscale ultrasound ○ Endoscopic ultrasonography (EUS) – Best technique for determining locoregional extent of tumor – Malignant nodes: Hypoechoic and well defined – Benign nodes: Hyperechoic; indistinct borders

Nuclear Medicine Findings • PET ○ FDG-18F positron emission tomography (FDG PET) – More sensitive and superior to CT in detecting regional and distant metastases

Imaging Recommendations • Double-contrast esophagography for detection • EUS for locoregional evaluation • CT and PET for metastases

DIFFERENTIAL DIAGNOSIS Reflux Esophagitis (With Stricture) • Concentric, smooth tapering of short distal segment ○ Distinguished by normal peristalsis in benign type ○ Lack of peristalsis in malignant stricture • Diagnosis: Endoscopic biopsy and history

Esophageal Intramural Benign Tumors • • • • •

Leiomyoma > > gastrointestinal stromal tumor Borders form right angles or obtuse angles with wall Round or ovoid filling defect, outlined by barium Usually have smooth, intact mucosa Ulceration of surface mucosa may mimic carcinoma

Esophageal Metastases and Lymphoma • May invade esophagus directly 229

Esophagus

Esophageal Carcinoma

• May cause irregular narrowing of lumen • History and imaging evidence of lung cancer

• Diagnosis: Endoscopic biopsy and histology

Radiation Esophagitis

• Age ○ Usually > 50 years • Gender ○ M:F = 4:1 • Ethnicity ○ African Americans > Caucasians (2:1) • Epidemiology ○ Increased incidence in Turkey, Iran, India, China, South Africa, France, Saudi Arabia ○ Dramatic change from squamous cell to adenocarcinoma prevalence in USA within past 20 years

• Irregular stricture of irradiated portion of esophagus • Check for history of lung, mediastinal, or other thoracic tumor

Foreign Body, Esophagus • Impacted meat bolus appears as polypoid, irregular filling defect • Incompletely distended esophagus below impaction may be mistaken for pathologic narrowing • Esophagram after foreign body removal may show underlying normal esophagus, Schatzki ring, stricture

Demographics

Natural History & Prognosis

PATHOLOGY General Features • Etiology ○ Squamous cell carcinoma – Smoking, alcohol, achalasia, lye strictures – Celiac disease, head and neck tumor – Plummer-Vinson syndrome, radiation, tylosis – Human papillomavirus, synergistic effect ○ Adenocarcinoma – Barrett esophagus accounts for almost all cases • Genetics ○ Genomic instability in patients with Barrett esophagus may increase risk of adenocarcinoma

Staging, Grading, & Classification • Spread: Local, lymphatic, hematogenous • TNM staging ○ Stage 0: Carcinoma in situ ○ Stage I: Lamina propria or submucosa ○ Stage IIA: Muscularis propria and adventitia ○ Stage IIB: Lamina propria, submucosa, muscularis propria, and regional lymph nodes ○ Stage III: Invades adjacent structures, regional lymph nodes, or any other nodes ○ Stage IV: All layers, same and any other nodes, or distant metastases

Gross Pathologic & Surgical Features • Infiltrating, polypoid, ulcerative, or varicoid lesions

• Complications ○ Fistula to trachea, bronchi, pericardium • Prognosis ○ Early cancer: 5-year survival = 90% ○ Advanced cancer: 5-year survival = < 10%

Treatment • Curative ○ Surgery, radiation (pre- and postoperative radiation) ○ Esophagectomy with gastric interposition is most common – Ivor-Lewis or alternate procedure • Palliative ○ Surgery, radiation, chemotherapy ○ Laser treatment, indwelling prosthesis

DIAGNOSTIC CHECKLIST Consider • Overlap of imaging findings with inflammatory causes of strictures and mucosal irregularity • Endoscopic biopsy often required

Image Interpretation Pearls • Irregular narrowing with nodular/ulcerated mucosa • Asymmetric contour with abrupt proximal borders of narrowed distal segment ("rat-tail" appearance)

SELECTED REFERENCES 1.

Microscopic Features • Squamous cell atypia; columnar glands • Adeno and squamous components

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Dysphagia (solids), odynophagia (painful swallowing), anorexia, weight loss, retrosternal pain • Clinical profile ○ Elderly patient with history of difficulty in swallowing solids and weight loss • Lab data ○ ± hypochromic, microcytic anemia ○ ± hemoccult-positive stool or decreased albumin 230

2.

3.

4. 5. 6.

Karashima R et al: Advantages of FDG-PET/CT over CT alone in the preoperative assessment of lymph node metastasis in patients with esophageal cancer. Surg Today. ePub, 2014 Napier KJ et al: Esophageal cancer: A Review of epidemiology, pathogenesis, staging workup and treatment modalities. World J Gastrointest Oncol. 6(5):112-20, 2014 Lewis RB et al: From the radiologic pathology archives: esophageal neoplasms: radiologic-pathologic correlation. Radiographics. 33(4):1083-108, 2013 Bird-Lieberman EL et al: Early diagnosis of oesophageal cancer. Br J Cancer. 101(1):1-6, 2009 Herszényi L et al: Diagnosis and recognition of early esophageal neoplasia. Dig Dis. 27(1):24-30, 2009 Gupta S et al: Usefulness of barium studies for differentiating benign and malignant strictures of the esophagus. AJR Am J Roentgenol. 180(3):737-44, 2003

Esophageal Carcinoma Esophagus

(Left) Esophagram shows an "apple core" constricting lesion of the distal esophagus. There is an abrupt transition, or shoulder, at the proximal end of the tumor as it abuts the normal esophagus. The mucosa through the tumor is destroyed with nodular contours. (Right) Esophagram in the same patient shows nodular thickened folds in the gastric cardia as well, strongly suggesting gastric extension of the tumor. Alternatively, gastric carcinoma may invade the distal esophagus.

(Left) Axial PET/CT shows intense FDG uptake within a primary esophageal cancer . (Right) Axial, more caudal PET/CT in the same patient shows intense FDG uptake within an aortocaval node , indicating metastases to the upper abdomen. There is also abnormal uptake within a left renal mass , which proved to be an unrelated primary renal cell carcinoma. PET/CT is the most effective means of evaluation for the total extent of disease and often affects management decisions.

(Left) Endoscopic ultrasound demonstrates an intraluminal mass that does not penetrate the muscularis propria (T1a adenocarcinoma). Endoluminal sonography is the best method for determining the depth of tumor invasion. (Right) Endoscopic photograph in the same patient shows an irregular polypoid mass in the distal esophagus. This adenocarcinoma was treated by esophagectomy with gastric interposition in the chest.

231

Esophagus

Esophageal Metastases and Lymphoma KEY FACTS

TERMINOLOGY • Primary lymphoma of esophagus or spread of extraesophageal cancer to esophagus

IMAGING • From gastric cancer: Ulcerated/polypoid mass of gastric cardia extending into distal esophagus • From lung cancer: Extrinsic indentation ± luminal narrowing of upper 1/2 of esophagus

TOP DIFFERENTIAL DIAGNOSES • Intramural benign esophageal tumor • Esophageal carcinoma • Esophageal varices

CLINICAL ISSUES • Most common signs/symptoms ○ Dysphagia, weight loss, hematemesis, or asymptomatic • Esophageal metastases

(Left) In this 60-year-old woman with lung cancer and progressive dysphagia, 2 views from an esophagram show extrinsic or intramural narrowing of the mid esophagus , but intact mucosal folds, representing invasion by her lung cancer. (Right) Esophagram in a man with known lung cancer and dysphagia shows a broad shelf-like indentation along the anterior wall of the mid esophagus.

(Left) In this 62-year-old man, a spot film of the distal esophagus shows a distal stricture and mucosal irregularity that mimics primary esophageal cancer. However, other views (not shown) showed nodular thickened folds in the gastric fundus. (Right) CT in the same patient shows a mass within the wall of the fundus with extension into the perigastric tissues and nodes. Endoscopy confirmed a primary gastric carcinoma.

232

○ Direct, lymphatic, or hematogenous spread ○ Direct invasion most common route: Gastric and lung cancer most common primary tumors • Complications ○ GI bleeding, perforation, obstruction • Treatment ○ Chemotherapy; radiation therapy ○ Surgical resection of complicating lesions (obstruction, upper GI bleed) ○ Endoluminal stent for obstructing lesions • Prognosis ○ Usually poor

DIAGNOSTIC CHECKLIST • Check for history of primary extraesophageal cancer; biopsy required • Overlapping radiographic features of esophageal metastases, lymphoma, and primary carcinoma

Esophageal Metastases and Lymphoma

Definitions • Metastases from primary cancer of other sites • Lymphoma: Malignant tumor of lymphocytes

IMAGING General Features

• Periesophageal and distal spread may be seen

Esophageal Varices • Serpiginous, longitudinal radiolucent filling defects • Easily distinguished from tumor by CT in most cases

PATHOLOGY General Features

• Best diagnostic clue ○ From gastric cancer: Ulcerated/polypoid mass of gastric cardia extending into distal esophagus ○ From lung cancer: Extrinsic indentation of upper esophagus from primary cancer or malignant adenopathy

• Associated abnormalities ○ Esophageal metastases – Direct, lymphatic, or hematogenous spread □ Direct invasion most common: From stomach (> 50%) and lung most often ○ Lymphoma; generalized adenopathy, AIDS

Radiographic Findings

Gross Pathologic & Surgical Features

• Fluoroscopic-guided double-contrast barium study ○ Direct invasion, gastric carcinoma: Distal esophagus – Ulcerated/polypoid mass of cardia/fundus – Irregular or smooth, tapered narrowing of distal esophagus ± discrete mass ○ Direct invasion of cancer of larynx, pharynx, thyroid, lung: Cervical or thoracic esophagus – Smooth or slightly irregular esophageal wall, soft tissue mass in adjacent neck/mediastinum – Serrated, scalloped, or nodular esophageal wall narrowing/obstruction ○ Contiguous involvement by mediastinal nodes (breast, lung cancer): Mid esophagus – Smooth, lobulated esophageal indentation or ulceration at level of carina ○ Hematogenous spread: Mid esophagus – Melanoma and breast are most common ○ Lymphoma, usually non-Hodgkin (NHL) – Often involves stomach as well – May be part of widespread lymphadenopathy ○ Primary intrinsic esophageal lymphoma (very rare) – Submucosal mass may simulate leiomyoma or other benign mural lesions

• Solitary/multiple, polypoid/ulcerated masses, stricture

CT Findings • Visualize primary tumor, esophageal extension • Detect mediastinal lymphadenopathy and extent

Ultrasonographic Findings • Grayscale ultrasound ○ Endoscopic ultrasonography (EUS) – Hypoechoic mass disrupting normal wall layers – Selective/diffusely thickened echogenic wall layers

DIFFERENTIAL DIAGNOSIS Esophageal Intramural Benign Tumor • Submucosal lesions arising within esophageal wall • Leiomyoma ○ Round/ovoid filling defect, outlined by barium ○ Borders form right or obtuse angles with wall

Esophagus

TERMINOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Dysphagia, weight loss, hematemesis

Demographics • Epidemiology ○ Usually in older adults (same demographics as for primary extraesophageal cancer) ○ Esophageal lymphoma – Least common site within GI tract (1% of cases) – Usually NHL, less commonly Hodgkin – Secondary lymphoma (90%) > > primary (10%) – Primary esophageal lymphoma seen in AIDS

Natural History & Prognosis • Complications: GI bleeding, perforation, obstruction • Prognosis: Usually poor

Treatment • Chemotherapy; radiation therapy • Endoluminal stent for obstructing lesions

DIAGNOSTIC CHECKLIST Consider • Check for history of primary extraesophageal cancer; biopsy required

Image Interpretation Pearls • Overlapping radiographic features of esophageal metastases, lymphoma, and primary carcinoma • Imaging important to identify and stage malignancy

SELECTED REFERENCES 1.

2.

Hayashi M et al: Mucosa-associated lymphoid tissue (MALT) lymphoma arising in the esophagus, stomach, and lung. Gen Thorac Cardiovasc Surg. 59(12):826-30, 2011 Ba-Ssalamah A et al: Dedicated multi-detector CT of the esophagus: spectrum of diseases. Abdom Imaging. 34(1):3-18, 2009

Esophageal Carcinoma • Polypoid, ulcerated, infiltrative types • Narrows lumen, abrupt borders ("rat tail") 233

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SECTION 4

Stomach

Introduction and Overview Imaging Approach to the Stomach

236

Congenital Gastric Diverticulum

242

,QƮDPPDWLRQ Gastritis Gastric Ulcer Zollinger-Ellison Syndrome Ménétrier Disease Caustic Gastroduodenal Injury

244 248 252 256 258

Degenerative Gastroparesis Gastric Bezoar Gastric Volvulus

259 260 262

Treatment Related Iatrogenic Injury: Feeding Tubes Partial Gastrectomy: Bilroth Procedures Fundoplication Complications Imaging of Bariatric Surgery

268 270 274 280

Benign Neoplasms Gastric Polyps Intramural Benign Gastric Tumors

286 290

Malignant Neoplasms Gastric GIST Gastric Carcinoma Gastric Metastases and Lymphoma

294 298 304

Stomach

Imaging Approach to the Stomach

Gastric Anatomy and Terminology The stomach is the alimentary reservoir for the mixing, grinding, and enzymatic digestion of food. It is divided into the cardia, fundus, body, antrum, and pylorus; each with its own specific function. The cardia is the portion of the stomach surrounding the esophageal orifice and the site where the lesser and greater curvatures meet. The fundus is the most cephalic part of the stomach and touches the left hemidiaphragm. The body is the main portion of the stomach and the principal site of acid production. The antrum is the prepyloric part of the stomach. The pylorus is the sphincter that controls emptying into the duodenum; it is formed by thickening of the middle layer of smooth muscle and a thin fibrous septum.

Mural Anatomy The gastric wall consists of 3 layers of smooth muscle; the outermost is the longitudinal muscle layer, the middle is the circular muscle layer, and the inner is the oblique muscle layer. The middle circular muscle layer is the thickest component. Gastric rugae are the redundant folds of gastric mucosa that are most prominent when the stomach is collapsed. The reservoir and mixing functions of the stomach demand a thick, expansile, muscular vessel which characterizes gastric morphology. Gastric mucosa is composed of columnar epithelium. Gastric glands vary in prevalence in different parts of the stomach. These produce mucin (to line and protect the gastric mucosa), pepsinogen (a precursor to pepsin needed for digestion), and hydrochloric acid (which activates digestive enzymes and assists with the breakdown of food).

Other Anatomical Considerations The stomach has a rich vascular supply, with the lesser curve supplied by branches of the left and right gastric arteries that run within the lesser omentum. Numerous collateral pathways arising from branches of the celiac and superior mesenteric arteries make the stomach and duodenum resistant to ischemic injury, as well as difficult to control by catheter embolotherapy in the setting of acute upper gastrointestinal hemorrhage. The greater curve is supplied by the left and right gastroomental (gastroepiploic) arteries that run within the greater omentum. In planning for partial gastrectomy, surgeons try to ensure an intact arterial supply from at least 1 of its 2 sources, preferably the gastroepiploic vessels. Venous drainage is into the portal system through the left and right gastric veins and via the splenic and superior mesenteric veins. All of these have collateral connections that become important in the event of venous occlusion or portal hypertension, when gastric varices may become prominent and hemorrhage. Lymphatic drainage follows the course of the arteries, then to celiac nodes via efferent lymphatic ducts. Inspection of these nodal groups is important in staging gastric malignancies. The rich lymphatic and venous drainage of the stomach accounts for the high prevalence of metastatic disease at the time of diagnosis of gastric carcinoma. The vagus nerve carries parasympathetic stimuli to the stomach, stimulating peristalsis and acid secretion. Surgical interruption of the vagus nerve has been used extensively to 236

treat acid-peptic disease, especially in the era before effective medical control. In order to prevent gastric retention, a vagotomy must be accompanied by some form of gastric emptying procedure, such as partial gastrectomy or pyloroplasty. Gastric diverticula occur with some regularity (though in less than 1%) and are likely to be mistaken for more significant abnormalities. These congenital, true diverticula usually arise near the gastric cardia. They often have only a thin connection to the stomach, and it may not be apparent on CT or MR. A completely fluid-filled diverticulum is often mistaken for an adrenal mass, while one containing both gas and fluid might be misdiagnosed as an abscess.

Imaging Issues Fluoroscopic barium studies are complementary to endoscopy and CT for most cases of dyspepsia and abdominal pain, and they are superior to endoscopy in the evaluation of functional abnormalities (e.g., reflux, or gastroparesis) In many radiology practices, the main role of barium studies is in the pre-/postoperative evaluation of patients undergoing gastric surgical procedures, such as esophagectomy with gastric pull-through, fundoplication for gastroesophageal reflux disease (GERD), partial gastrectomy for cancer, or some form of bariatric surgery. Radiologists must become familiar with the range of expected alterations following various surgical procedures, as well as the numerous complications that may result. Since clinical signs and symptoms are often lacking or nonspecific in these patients, radiologists are often the first to recognize adverse results of surgery. CT has become the principal means of staging primary and metastatic tumors involving the stomach. CT is complementary to upper GI series and endoscopy in diagnosing gastritis and gastric ulcers, especially with complications such as perforation. CT has a primary role in diagnosing inflammatory processes that affect the stomach secondarily, such as pancreatitis. Endoscopy is the most accurate means of diagnosing gastric carcinoma and primary inflammatory conditions, such as gastritis. However, endoscopy may fail to detect submucosal gastric masses, such as lymphoma or GI stromal tumors, in which the overlying mucosa is often normal.

Approach to the Thick-Walled Stomach The presence of "thickened folds" on an upper GI series is a finding of limited value in isolation because so many intrinsic and extrinsic processes, inflammatory or malignant, may result in this finding. CT findings help to narrow the differential diagnosis by allowing characterization of the nature of the wall thickening. As with the small bowel and colon, inflammatory processes (such as gastritis) result in submucosal edema, which appears as a layer of hypodensity (near water attenuation) between the mucosa and serosa. Soft tissue density within the wall is more likely to be of neoplastic origin. CT may also allow distinction among the various gastric neoplasms. Primary carcinoma usually produces nodular, irregular wall thickening with limited distensibility, often with evidence of metastatic spread to the liver, regional nodes, ± omentum.

Imaging Approach to the Stomach

A gastric GIST (stromal tumor) usually appears as a submucosal, mostly exophytic gastric mass. While the mucosa is intact over a small GIST, large lesions often have ulcerated mucosa, which, along with central cavitation of the tumor, may be evident as a large perigastric mass containing gas, fluid, and enteric contrast medium. The "global view" allowed by CT often provides other clues to the etiology of thickened folds, such as evidence of pancreatitis, the presence of an islet cell tumor in ZollingerEllison syndrome, or cirrhosis and signs of portal hypertension in a patient with gastric varices.

Differential Diagnosis Gastric Mass Lesions Common • Gastric carcinoma • Hyperplastic polyps • Artifacts (air/gas bubbles, apposed walls of stomach) • Adenomatous polyp • Intramural benign gastric tumors • Bezoar (mimic) • Perigastric mass (mimic): Splenomegaly, renal cell carcinoma, hepatocellular carcinoma, splenosis • Gastric varices Less Common • Gastric metastases and lymphoma • Mesenchymal tumors (e.g., GIST, lipoma, neural tumor) • Gardner syndrome • Hamartomatous polyposis syndromes • Ectopic pancreatic tissue • Hematoma • Duplication cyst Intramural Mass Common • Gastric varices • Pancreatic pseudocyst • Metastases and lymphoma • Mesenchymal tumors (e.g., GIST, lipoma, neural tumor) Less Common • Gastric intramural hematoma • Ectopic pancreatic tissue • Accessory spleen or splenosis • Gastric duplication cyst Thickened Gastric Folds Common • Gastritis • Gastric ulcer • Portal hypertension, varices • Gastric carcinoma • Pancreatitis, acute; pancreatic pseudocyst • Portal hypertensive gastropathy Less Common • Gastric metastases and lymphoma • Ménétrier disease • Zollinger-Ellison syndrome • Caustic gastroduodenal injury • Crohn disease

Rare but Important • Tuberculosis • Radiation gastritis • Amyloidosis • Eosinophilic gastritis • Chemotherapy-induced gastritis • Sarcoidosis

Stomach

Gastric lymphoma often causes massive nodular thickening of folds but uncommonly limits distensibility or causes gastric outlet obstruction. Lymphoma and gastric metastases are often accompanied by extragastric sites of tumor.

"Target" or Bull's-Eye Lesions Common • Gastric metastases • Gastric lymphoma • Kaposi sarcoma Less Common • Gastric carcinoma • Ectopic pancreatic tissue • Carcinoid • Gastric stromal tumor Gastric Ulceration (Without Mass) Common • NSAID-induced gastritis • Gastritis (other causes) • Gastric ulcer Less Common • Gastric carcinoma • Zollinger-Ellison syndrome • Crohn disease • Caustic gastroduodenal injury Intrathoracic Stomach Common • Hiatal hernia • Post esophagectomy • Achalasia, esophagus (mimic) Less Common • Postoperative fluid collection (mimic) • Pulsion diverticulum, esophagus Gastric Antral Narrowing Common • Gastritis • Normal variant • Gastric ulcer • Gastric carcinoma • Acute pancreatitis • Post gastric surgery state • Hypertrophic pyloric stenosis Less Common • Gastric GIST • Gastric metastases and lymphoma • Caustic gastroduodenal injury • Crohn disease Rare but Important • Tuberculosis • Syphilis • Sarcoidosis • Opportunistic infections Gastric Dilation or Outlet Obstruction Common • Gastric or duodenal ulcer • Gastric carcinoma • Gastroparesis • Postoperative state • Gastric volvulus 237

Stomach

Imaging Approach to the Stomach

Less Common • Pancreatitis, acute • Pancreatitis, chronic • Metastases and lymphoma • Duodenal mass or stricture: Carcinoma, metastases, annular pancreas • Gastric polyps • SMA syndrome Rare but Important • Infiltrating lesions: Crohn disease, sarcoidosis, tuberculosis,etc. Linitis Plastica, Limited Distensibility Common • Gastric carcinoma • Metastases and lymphoma Less Common • Caustic gastroduodenal injury • Peritoneal metastases • Gastritis • Opportunistic infection Rare but Important • Crohn disease • Following gastric freezing • Syphilis • Radiation-induced gastritis • Infiltrative granulomatous diseases: Tuberculosis, sarcoidosis, amyloidosis Epigastric Pain Common • Functional dyspepsia • Reflux esophagitis • Duodenal ulcer • Gastric ulcer • Gastritis • Cholecystitis • Choledocholithiasis • Cholangitis, ascending • Hepatitis • Pancreatitis, acute • Pancreatitis, chronic • Pancreatic pseudocyst • Coronary artery disease • Gastric carcinoma • Pancreatic ductal carcinoma • Sphincter of Oddi dysfunction • Psychosomatic disorders • Hepatic or pancreatic trauma • Hiatal or ventral hernia Less Common • Crohn disease • Other gastric causes: Ménétrier disease, caustic gastroduodenal injury, GIST, gastric metastases and lymphoma • Other hepatic causes: Neoplasms, infections, inflammation, ischemia • Other pancreatic causes: Pancreas divisum, pancreatic neoplasms 238

• Other duodenal causes: Carcinoma, metastases and lymphoma, • Musculoskeletal etiologies

• Hypertrophic pyloric stenosis • Gastric ileus

Left Upper Quadrant Mass Common • Splenomegaly and splenic masses • Hepatomegaly and hepatic masses • Gastric masses and distention • Pancreatic neoplasms and pseudocysts • Adrenal masses • Abdominal abscess • Hematoma/seroma • Peritoneal metastases • Renal masses Less Common • Gastric diverticulum • Retroperitoneal sarcoma • Pseudomyxoma peritonei • Abdominal wall masses: Hernia, neoplasms • Gastric volvulus • Loculated &/or malignant ascites

Selected References 1.

2.

3. 4. 5. 6. 7.

8.

9. 10.

11. 12. 13.

Foley KG et al: N-staging of oesophageal and junctional carcinoma: is there still a role for EUS in patients staged N0 at PET/CT? Clin Radiol. 69(9):959-64, 2014 Yoshikawa T et al: Accuracy of CT staging of locally advanced gastric cancer after neoadjuvant chemotherapy: cohort evaluation within a randomized phase II study. Ann Surg Oncol. 21 Suppl 3:S385-9, 2014 Ba-Ssalamah A et al: Texture-based classification of different gastric tumors at contrast-enhanced CT. Eur J Radiol. 82(10):e537-43, 2013 Yi JH et al: 18F-FDG uptake and its clinical relevance in primary gastric lymphoma. Hematol Oncol. 28(2):57-61, 2010 Noguera JJ et al: Gastric diverticulum mimicking cystic lesion in left adrenal gland. Urology. 73(5):997-8, 2009 Shiotani A et al: The preventive factors for aspirin-induced peptic ulcer: aspirin ulcer and corpus atrophy. J Gastroenterol. 44(7):717-25, 2009 Chen BB et al: Preoperative diagnosis of gastric tumors by three-dimensional multidetector row ct and double contrast barium meal study: correlation with surgical and histologic results. J Formos Med Assoc. 106(11):943-52, 2007 Chen CY et al: Gastric cancer: preoperative local staging with 3D multidetector row CT--correlation with surgical and histopathologic results. Radiology. 242(2):472-82, 2007 Chen CY et al: Staging of gastric cancer with 16-channel MDCT. Abdom Imaging. 31(5):514-20, 2006 Kim JH et al: Imaging of various gastric lesions with 2D MPR and CT gastrography performed with multidetector CT. Radiographics. 26(4):110116; discussion 1117-8, 2006 Kim AY et al: Gastric cancer by multidetector row CT: preoperative staging. Abdom Imaging. 30(4):465-72, 2005 Ba-Ssalamah A et al: Dedicated multidetector CT of the stomach: spectrum of diseases. Radiographics. 23(3):625-44, 2003 Insko EK et al: Benign and malignant lesions of the stomach: evaluation of CT criteria for differentiation. Radiology. 228(1):166-71, 2003

Imaging Approach to the Stomach Stomach

Esophageal branch of left gastric artery Inferior phrenic arteries Left gastric artery Right gastric artery

Splenic artery Left gastroepiploic artery

Right gastroepiploic artery

Branches of left and right gastric arteries

Hepatogastric ligament Hepatoduodenal ligament

Pyloric sphincter

Outer (longitudinal) muscle layer Middle (circular) muscle layer

(Top) In "conventional" arterial anatomy of the stomach and duodenum (present in only 50% of the population), the left gastric artery arises from the celiac trunk, supplies the lesser curvature, and anastomoses with the right gastric artery, a branch of the proper hepatic artery. The greater curvature of the stomach is supplied by anastomosing branches of the gastroepiploic arteries, with the left arising from the splenic artery. (Bottom) The lesser omentum extends from the stomach to the porta hepatis and can be divided into the broader, thinner hepatogastric ligament and the thicker hepatoduodenal ligament. Note the layers of gastric muscle, with the middle circular layer being the thickest.

239

Stomach

Imaging Approach to the Stomach

(Left) Axial CECT shows a near water density LUQ mass that might be mistaken for an adrenal adenoma or other lesion. Its contiguity with the stomach and a tiny bubble of gas suggest the correct etiology of gastric diverticulum. (Right) An upright film from an upper GI series in the same patient shows the juxtacardiac diverticulum with an airfluid level.

(Left) In this patient who had chest pain following recent Nissen fundoplication and reduction of a large paraesophageal hernia, CT shows collections of gas and fluid within the mediastinum, suggestive, but not diagnostic of a leak or perforation. (Right) CT in the same case shows intraabdominal extension of gas . Bilateral pleural effusions are also noted.

(Left) Another CT section in the same case shows the intact fundoplication , compressing the distal esophagus and proximal stomach. (Right) A spot film from an esophagram in the same case shows compression of the distal esophagus from an intact fundoplication. Leak of contrast material into the mediastinum and upper abdomen, however, confirms perforation (leak) of the esophagus or the gastric wrap itself.

240

Imaging Approach to the Stomach Stomach

(Left) Film from an upper GI series 1 day following gastric banding procedure shows the gastric band around the proximal stomach with the correct orientation. A leak of water-soluble contrast medium and gas is evident . (Right) Upright spot film in a patient who had recent Rouxen-Y gastric bypass surgery shows a spherical distention of the gastric pouch , with an air-fluid level and delayed emptying, signs of a stricture of the anastomosis between the gastric pouch and the Roux limb.

(Left) Axial CECT in a young man with severe abdominal pain due to NSAID gastritis shows massive thickening and edema of the gastric wall . Note the enhancing mucosa as distinct from near water density submucosal edema . (Right) Axial CECT in a patient with gastric carcinoma shows a distended stomach (outlet obstruction) with a contracted antrum, thickened wall , and submucosal soft tissue density. Adjacent lymphadenopathy indicates spread beyond the stomach.

(Left) In this patient with a palpable left upper quadrant mass, CT shows features of a gastric GIST. The stomach is indented along its dorsal surface by the mass , which is necrotic in its center and contains a gas-fluid level due to communication with the gastric lumen. (Right) A film from an upper GI series shows that the stomach is extremely reduced in size and was rigid and nonperistaltic. This linitis plastica appearance was the result of caustic ingestion (drain cleaner), but can also result from primary or metastatic carcinoma.

241

Stomach

Gastric Diverticulum KEY FACTS

IMAGING

PATHOLOGY

• Most (> 75%) are juxtacardiac diverticula ○ Near gastroesophageal (GE) junction, on posterior aspect of lesser curvature of stomach • Usually 1-3 cm, up to 10 cm in diameter • On upper GI series ○ Barium-filled diverticulum with air-fluid level • CT findings ○ Often in suprarenal location – Mimics adrenal or pancreatic mass ○ Connection to stomach may be subtle ○ Air-filled, fluid-filled, or contrast-filled mass ○ No enhancement of contents

• Pouch/sac includes 3 normal layers of bowel wall: Mucosa, submucosa, and muscularis propria

TOP DIFFERENTIAL DIAGNOSES • • • •

Adrenal mass Pancreatic tumor Abdominal abscess Ectopic pancreatic tissue

(Left) Upright film from an upper GI series shows a typical gastric diverticulum with an air-contrast level seen within an outpouching near the gastric cardia. (Right) Axial CECT in the same patient shows a near water density mass projecting posterior to the gastric fundus . The connection to the stomach is much more difficult to see on CT. Distention of the stomach with oral contrast or gas granules may be required to make the diagnosis on a CT scan.

(Left) CECT shows an oval mass containing water density fluid and gas. On more cephalic sections, the "mass" was contiguous with the posterior wall of the fundus. (Right) On a slightly more inferior image, note how the diverticulum extends dorsal to the pancreas and splenic vein. Without the presence of the air-fluid level it would be difficult to distinguish this from an adrenal mass. An upper GI series confirmed a typical juxtacardiac diverticulum.

242

CLINICAL ISSUES • Complications (rare) ○ Bleeding ○ Ulceration ○ Carcinoma • No treatment needed unless complications occur

DIAGNOSTIC CHECKLIST • Incidental finding that may be mistaken for adrenal mass on CT or MR ○ Barium studies or CT in supine and prone position with oral contrast and gas granules will differentiate diverticulum from mass

Gastric Diverticulum

Definitions

Ectopic Pancreatic Tissue • May also cause outpouching from antrum within mound of tissue

Stomach

TERMINOLOGY • Pouch or sac opening from stomach

IMAGING General Features • Best diagnostic clue ○ Barium-filled diverticulum from fundus, near gastroesophageal (GE) junction • Other general features ○ 2 types of gastric diverticula – True gastric diverticula (congenital) – Intramural or partial gastric diverticula (acquired)

Radiographic Findings • Fluoroscopic-guided barium studies ○ True diverticula – Most (> 75%) are juxtacardiac diverticula: Diverticula near GE junction, on posterior aspect of lesser curvature of stomach – Usually 1-3 cm, up to 10 cm in diameter – Barium-filled diverticulum with air-fluid level – Pooling of barium; mimics ulceration – In antrum (rare); mimics ulcer craters ○ Intramural or partial gastric diverticula – Most are prepyloric diverticula: Diverticula at greater curvature of distal antrum – Heaped-up area overlying diverticulum; mimics ectopic pancreatic rest on greater curvature

CT Findings • Abnormal rounded "lesion" ○ Often in suprarenal location; mimics adrenal mass ○ Connection to stomach may be subtle • Air-filled, fluid-filled, or contrast-filled mass • No enhancement of contents

Imaging Recommendations • Best imaging tool ○ Fluoroscopic-guided barium studies • Protocol advice ○ Juxtacardiac diverticula are best seen in lateral views on barium studies ○ Obtain CT in supine and prone position: Air will usually fill diverticulum

DIFFERENTIAL DIAGNOSIS Adrenal Mass • CT: Diverticular contents do not enhance, adrenal masses (except cysts) do enhance • Distinguished by barium studies

Pancreatic Tumor • e.g., any cystic or solid lesion

Abdominal Abscess • Air- or fluid-filled mass with thick wall • Distinguished by clinical history (e.g., fever)

PATHOLOGY General Features • Etiology ○ True gastric diverticula: Congenital ○ Intramural or partial gastric diverticula: Acquired – Associated with peptic ulcer disease, pancreatitis, cholecystitis, malignancy, or outlet obstruction • Uncommon or rare ○ 0.02% of autopsy specimens ○ 0.04% of upper gastrointestinal series ○ > 75% of gastric diverticula are juxtacardiac

Gross Pathologic & Surgical Features • True gastric diverticula ○ Pouch/sac includes 3 normal layers of bowel wall: Mucosa, submucosa, muscularis propria

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ True gastric diverticula – Asymptomatic (most common) – Vague upper abdominal pain ○ Intramural or partial gastric diverticula – Asymptomatic, or related to associated diseases (e.g., peptic ulcer) • Diagnosis ○ Upper GI series or CT

Demographics • Age ○ Any age • Gender ○ M:F = 1:1

Natural History & Prognosis • Complications (rare): Bleeding, ulceration, carcinoma

Treatment • No treatment needed unless complications occur • If with complications, diverticulectomy or partial gastrectomy can be used to resect diverticulum

DIAGNOSTIC CHECKLIST Consider • Often mistaken for adrenal mass on CT or MR

Image Interpretation Pearls • Barium studies or CT in supine and prone position with oral contrast and gas granules

SELECTED REFERENCES 1.

Hajini FF et al: Gastric diverticulum a rare endoscopic finding. BMJ Case Rep. 2014, 2014

243

Stomach

Gastritis KEY FACTS

TERMINOLOGY • Inflammation of gastric mucosa induced by group of disorders that differ clinically but share similar imaging features ○ Common etiologies include Helicobacter pylori, NSAIDs, steroids, alcohol and coffee, stress

IMAGING • Erosive gastritis, complete or varioliform erosions (most common type) ○ Erosions surrounded by radiolucent halos of edematous, elevated mucosa ○ Scalloped or nodular antral folds ○ Crenulation or irregularity of lesser curvature ○ Location: Gastric antrum on crests of rugal folds ○ Prolapse of antral mucosa through pylorus ○ Lack of complete distensibility of stomach (especially antrum) • CT: Decreased wall attenuation (edema or inflammation)

(Left) Graphic shows an ulcer crater and numerous mucosal erosions, mostly in the antrum along the ridges of hypertrophied folds. The antrum is less than completely distensible. (Right) Upper GI series shows rows of varioliform erosions along the tops of hypertrophied gastric antral folds. This is diagnostic of gastritis but not specific as to the etiology.

(Left) CT of an athletic 30year-old woman with severe abdominal pain and nausea due to NSAID gastritis shows massive thickening of the gastric wall with marked edema of the submucosa . The enhancing mucosa imparts a striped appearance to the gastric wall. (Right) The body and antrum of the same patient are similarly involved . Following cessation of ibuprofen use and beginning antacid therapy, the patient's symptoms resolved and a repeat CT scan (not shown) was normal.

244

○ Close to water density • Upper GI series best for mucosal detail ○ CT for global view and concern for extragastric complications (e.g., perforation)

TOP DIFFERENTIAL DIAGNOSES • • • •

Gastric carcinoma Zollinger-Ellison syndrome Acute pancreatitis Gastric metastases and lymphoma

DIAGNOSTIC CHECKLIST • CT and upper GI usually suggest only gastritis ○ Specific etiology is determined by other medical data ± endoscopic biopsy

Gastritis

Definitions • Inflammation of gastric mucosa induced by group of disorders that differs in etiological, clinical, histological, and radiological findings • Classification of gastritis ○ Erosive or hemorrhagic gastritis (2 types) – Complete or varioliform – Incomplete or "flat" ○ Antral gastritis ○ Helicobacter pylori gastritis ○ Hypertrophic gastritis ○ Atrophic gastritis (2 types: A and B) ○ Granulomatous gastritis (Crohn disease and tuberculosis) ○ Eosinophilic gastritis ○ Emphysematous gastritis ○ Caustic ingestion gastritis ○ Radiation gastritis ○ AIDS-related gastritis: Viral, fungal, protozoal, and parasitic infections

IMAGING General Features • Best diagnostic clue ○ Superficial ulcers and thickened folds

Upper GI Findings • Erosive gastritis, complete or varioliform erosions (most common type) ○ Location: Gastric antrum on crests of rugal folds ○ Multiple punctate or slit-like collections of barium ○ Erosions surrounded by radiolucent halos of edematous, elevated mucosa ○ Scalloped or nodular antral folds ○ Epithelial nodules or polyps (chronic) • Nonsteroidal anti-inflammatory drug (NSAID) induced ○ Linear or serpiginous erosions clustered in body, on or near greater curvature ○ Varioliform or linear erosions in antrum ○ NSAID-related gastropathy: Subtle flattening and deformity of greater curvature of antrum • Antral gastritis ○ Thickened folds, spasm, or decreased distensibility ○ Scalloped or lobulated folds oriented longitudinally or transverse folds ○ Crenulation or irregularity of lesser curvature ○ Prolapse of antral mucosa through pylorus • H. pylori gastritis ○ Location: Antrum, body, or occasionally fundus; diffuse or localized ○ Thickened, lobulated gastric folds ○ Enlarged areae gastricae ( 3 mm in diameter) • Hypertrophic gastritis ○ Location: Fundus and body ○ Markedly thickened, lobulated gastric folds • Atrophic gastritis ○ Narrowed, tubular, nondistensible stomach ○ Smooth, featureless mucosa, folds ○ Small (1-2 mm in diameter) or absent areae gastricae

• Granulomatous gastritis, Crohn disease ○ Location: Antrum and body ○ Multiple aphthous ulcers ○ Acute: Indistinguishable from erosive gastritis ○ Advanced disease large ulcers, thickened folds, nodular or "cobblestone" mucosa ○ Ram's horn sign: Tubular, narrowed, funnel-shaped antrum • Granulomatous gastritis, tuberculosis ○ Location: Lesser curvature of antrum or pylorus ○ Antral narrowing obstruction ○ Often involves duodenum as well • Eosinophilic gastritis ○ Location: Antrum and body ○ Mucosal nodularity, thickened folds, antral narrowing and rigidity • Emphysematous gastritis ○ Gas in wall of stomach; no positional change ○ Note: Use water-soluble contrast for upper GI • Caustic ingestion (use water-soluble contrast) ○ Acute: Ulceration, thickened folds, gastric atony; mural defects ○ Chronic: Antral narrowing and deformity – May progress to linitis plastica or perforation • Radiation gastritis ○ Acute: Ulceration, thickened folds, gastroparesis or spasm ○ Chronic: Antral narrowing and deformity (scarring) • AIDS-related gastritis ○ Mucosal nodularity, erosions, ulcers, thickened folds, or antral narrowing

Stomach

TERMINOLOGY

CT Findings • Decreased wall attenuation (edema or inflammation) ○ Target or halo: Mucosal enhancement and decreased density of submucosa (edema) • Thickened gastric folds or wall • H. pylori gastritis: Circumferential antral wall thickening or focal thickening of posterior gastric wall along greater curvature • Emphysematous gastritis: Thickened wall and gas within wall ○ May have portal venous gas

Imaging Recommendations • Best imaging tool ○ Upper GI series for mucosal detail ○ CT for global view and concern for extragastric complications (e.g., perforation)

DIFFERENTIAL DIAGNOSIS Gastric Carcinoma • Differentiate from gastritis by loss of distensibility and decreased or absent peristalsis in involved portion ○ Nodular, distorted mucosa ○ Submucosa of soft tissue density

Zollinger-Ellison Syndrome • Thickened gastric folds in fundus and body (edema, inflammation, and hyperplasia) • fluids in lumen and ulcers at unusual locations 245

Stomach

Gastritis

• Due to gastrinoma (pancreatic endocrine tumor)

Acute Pancreatitis • Common cause of gastric wall thickening

Gastric Metastases and Lymphoma • CT: Submucosal tumor is soft tissue (not water) density • Metastases (e.g., malignant melanoma, breast cancer) ○ Tend to restrict distention • Gastric lymphoma ○ Markedly thickened wall without outlet obstruction

PATHOLOGY General Features • Etiology ○ Erosive: NSAIDs, alcohol, steroids, stress, trauma, burns, or infections ○ Atrophic: Fundus and body (autoimmune) ○ Antral: Alcohol, tobacco, coffee, bile, or H. pylori ○ Granulomatous: Crohn disease, sarcoidosis, tuberculosis, syphilis, or candidiasis ○ Emphysematous: Escherichia coli, Staphylococcus aureus, Clostridium perfringens, or Proteus vulgaris ○ Caustic ingestion: Strong acids (hydrochloric, sulfuric, etc.) or alkali ○ Radiation > 5,000 rads ○ AIDS related: Cytomegalovirus, cryptosporidiosis, toxoplasmosis, or strongyloidiasis • Associated abnormalities ○ Atrophic gastritis: 90% of patients have pernicious anemia patients ○ Hypertrophic gastritis: 66% of patients have duodenal ulcers

Gross Pathologic & Surgical Features • Erosive gastritis: Areas of congested, edematous, or ulcerated mucosa • Atrophic gastritis: Thin smooth mucosa, flattened rugae, or tubular stomach ○ Loss of parietal or chief cells

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic in some ○ Epigastric pain, nausea, vomiting, or hematemesis • Lab data ○ leukocytes; positive fecal occult blood test ○ Atrophic gastritis: vitamin B12 ○ Positive H. pylori (endoscopy, histology, cultures, urea breath, and serologic tests)

Natural History & Prognosis • Caustic ingestion gastritis: Acute severe phase (1-4 days), ulceration and spasm; chronic phase (3-4 weeks) cicatrization and scarring (linitis plastica) • Radiation gastritis: Inflammation (1-6 months), scarring and fibrosis (> 6 months) • Complications ○ Gastric or duodenal ulcer, pernicious anemia, low-grade MALT lymphoma or gastric carcinoma 246

○ Eosinophilic gastritis: Gastric outlet obstruction ○ Caustic ingestion gastritis: Gastric necrosis • Prognosis ○ Erosive, antral, H. pylori, and atrophic gastritis: Good after treatment ○ Eosinophilic gastritis: Chronic, relapsing disease with intermittent exacerbation and asymptomatic intervals ○ Emphysematous gastritis: 60-80% mortality

Treatment • Stop offending agents: Alcohol, tobacco, NSAIDs, steroids, and coffee • H. pylori treatment: Metronidazole, bismuth and clarithromycin, amoxicillin or tetracycline • Hypertrophic gastritis: Antisecretory agents (H2-receptor antagonists or proton-pump inhibitors) • Atrophic gastritis: Replace vitamin B12 • Eosinophilic gastritis: Steroids • Emphysematous gastritis: IV fluids, antibiotics, but no nasogastric tube • Caustic ingestion gastritis: Steroids, antibiotics, parenteral feedings, surgery

DIAGNOSTIC CHECKLIST Consider • History and presence of H. pylori infection

Image Interpretation Pearls • H. pylori gastritis: Thickened, lobulated gastric folds with enlarged areae gastricae • Erosive gastritis: Multiple collections of barium surrounded by radiolucent halos of edematous, elevated mucosa

Reporting Tips • CT and upper GI usually just suggest gastritis ○ Specific etiology determined by other medical data ± endoscopic biopsy

SELECTED REFERENCES 1. 2. 3. 4. 5. 6. 7.

8.

Byrne D et al: Imaging findings in emphysematous gastritis. Ir Med J. 107(2):60-1, 2014 Kim HW et al: Atrophic Gastritis: A Related Factor for Osteoporosis in Elderly Women. PLoS One. 9(7):e101852, 2014 Makhoul E et al: Emphysematous gastritis. Acta Gastroenterol Belg. 76(4):445-6, 2013 Gonen C et al: Magnifying endoscopic features of granulomatous gastritis. Dig Dis Sci. 54(7):1602-3, 2009 Yüksel O et al: Erosive gastritis mimicking watermelon stomach. Am J Gastroenterol. 104(6):1606-7, 2009 Horton KM et al: Current role of CT in imaging of the stomach. Radiographics. 23(1):75-87, 2003 Bender GN et al: Double-contrast barium examination of the upper gastrointestinal tract with nonendoscopic biopsy: findings in 100 patients. Radiology. 202(2):355-9, 1997 Sohn J et al: Helicobacter pylori gastritis: radiographic findings. Radiology. 195(3):763-7, 1995

Gastritis Stomach

(Left) CT of antral gastritis in a 54-year-old man shows a thickened and hyperemic gastric wall . The antrum is contracted with a particularly thickened and edematous wall . The gallbladder is noted. The base of the duodenal bulb is indented. (Right) Upper GI series in the same patient shows a nondistensible antrum with thickened, nodular folds and herniation of gastric folds into the duodenal bulb . These are classic CT and upper GI features of antral gastritis.

(Left) Axial CECT of radiation gastritis in a patient with pancreatic cancer shows a stent in the bile duct and metallic fiducial markers that were placed at the time of surgical exploration to serve as markers for subsequent radiation therapy. Note the thick-walled stomach with submucosal edema limited to the radiation port. (Right) In the same patient, note the findings of gastritis limited to the radiation field in front of the pancreatic head and neck tumor.

(Left) An upright spot film from an upper GI series in this patient with atrophic gastritis shows almost complete absence of gastric folds. (Right) Upper GI series in a patient with chronic Crohn gastritis shows a deformed stomach that is reduced in size, with loss of normal gastric folds, and a tubular, funnel-shaped antrum that has been likened to a ram's horn.

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Stomach

Gastric Ulcer KEY FACTS

IMAGING • Benign gastric ulcer ○ Sharply defined mucosal defect (ulcer); smooth, even, radiating folds to edge of ulcer crater ○ Projects beyond expected contour of stomach (on upper GI and CT imaging) ○ Usually on lesser curve, posterior wall, or antrum ○ CT may show extravasation of gas and oral contrast (lesser sac or greater peritoneal cavity) • Malignant ulcer ○ Uneven shape; irregular or asymmetric edges; interruption and clubbing of radiating folds ○ Does not project beyond contour of stomach ○ CT may show metastasis to nodes, peritoneum, liver • Imaging for diagnosis ○ Upper GI series to show ulcer ○ CT to show complications (± ulcer itself)

(Left) Graphic shows a gastric ulcer with smooth gastric folds radiating to the edge of the ulcer crater. Note the infolding of the gastric wall "pointing" toward the ulcer, known as the incisura sign. (Right) Film from an upper GI series shows an ulcer niche projecting off the lesser curve of the antrum. Note the smooth gastric folds that radiate to the edge of the ulcer crater.

(Left) CECT of a perforated gastric ulcer shows thickening of the antral wall and submucosal edema , along with free intraperitoneal gas and ascites . The patient was taken to surgery where a perforated antral ulcer was oversewn along with an omental patch. (Right) A subsequent upper GI series in the same patient shows a large prepyloric ulcer as a fixed outpouching of barium. The antrum and pylorus are distorted.

248

○ CT gastroscopy in experienced hands may compete with endoscopy • Sump ulcers: Distal 1/2 of greater curvature (NSAIDs) • Incisura defect: Smooth or narrow indentation on curvature opposite ulcer (muscle contraction)

TOP DIFFERENTIAL DIAGNOSES • • • •

Gastritis Gastric GIST Gastric metastases and lymphoma Artifactual

PATHOLOGY • 2 major risk factors: H. pylori (60-80%) and NSAIDs (20%)

CLINICAL ISSUES • Benign (95%), malignant (5%) • Often multiple: 20-30% prevalence • Complications: Hemorrhage, perforation, gastric outlet obstruction, and fistula

Gastric Ulcer

Abbreviations • Gastric ulcer (GU)

Definitions • Inflammatory erosion of gastric mucosa ± submucosal or deeper penetration

IMAGING General Features • Best diagnostic clue ○ Sharply marginated barium collection with folds radiating to edge of ulcer crater on upper GI series • Location ○ Benign GU – Most common on lesser curvature or posterior wall of antrum or body – 3-11% on greater curvature, 1-7% on anterior wall ○ Malignant GU – Usually on greater curvature • Morphology ○ Same criteria are used for findings on upper GI series, CT virtual gastroscopy, and endoscopy ○ Benign GU – Sharply defined mucosal defect (ulcer); smooth, even, radiating folds to edge of ulcer crater – Ulcer projects beyond expected contour of stomach (on upper GI and CT imaging) ○ Malignant GU – Uneven shape; irregular or asymmetric edges; interruption and clubbing of radiating folds – Does not project beyond contour of stomach

– Nodular, clubbed, fused, or amputated folds

CT Findings • CECT (use water or water-soluble oral contrast, with oral gas granules to optimally distend stomach) ○ May visualize ulcer itself as outpouching ○ Associated signs – Wall thickening ± luminal narrowing of stomach – Submucosal edema – Infiltration of surrounding fat or organs (pancreas, liver) – Free air or oral contrast in abdomen or lesser sac □ Small amount to massive – Malignant GU □ May detect local nodes, peritoneal and liver metastases ○ Virtual gastroscopy – Obtain thin axial sections with gas distention of lumen – Construct MPR and 3D views of gastric lumen – Reported to detect benign and malignant GU with accuracy comparable to endoscopy

Stomach

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Upper GI series to show ulcer ○ CT to show complications (± ulcer itself) ○ CT gastroscopy (in experienced hands) may compete with endoscopy • Protocol advice ○ Upper GI: Add prone compression views of gastric antrum and body in single contrast phase of exam (with additional thin barium by mouth)

DIFFERENTIAL DIAGNOSIS

Radiographic Findings

Gastritis

• Upper GI series ○ Benign GU, profile view – Ulcer crater: Round or ovoid collections of barium – Hampton line: Thin radiolucent line separating barium in gastric lumen from barium in crater – Ulcer mound: Smooth, bilobed hemispheric mass projecting into lumen on both sides of ulcer; outer borders form obtuse, gently sloping angles with adjacent gastric wall (edema or inflammation) – Ulcer collar: Radiolucent rim of edematous mucosa around ulcer – Ulcer projecting beyond gastric wall – Smooth, symmetric radiating folds to edge of ulcer crater – Incisura defect: Smooth or narrow indentation on curvature opposite ulcer (muscle contraction) – Sump ulcers: Distal 1/2 of greater curvature (due to NSAIDs) ○ Malignant GU, profile – Carman meniscus sign: Ulcer crater and radiolucent elevated border – Does not project beyond expected gastric contour – Discrete tumor mass forms acute angles ○ Malignant GU, en face view – Irregular crater eccentrically located within tumor mass

• Markedly thickened gastric folds; shallow erosions • Limited distensibility, usually of antrum • Helicobacter pylori gastritis ○ Thickened gastric folds in antrum or body ○ Enlarged areae gastricae ( 3 mm)

Gastric Stromal Tumor (GIST) • Often more evident on CT, as much of mass is exophytic • > 2 cm ulcerated, central contrast-filled crater within smooth or slightly lobulated submucosal mass (bull's-eye or "target" lesions) • Upper GI: Submucosal mass with smooth surface, etched in white; borders form right angles or slightly obtuse angles with gastric wall

Gastric Metastases and Lymphoma • Malignant melanoma ○ Most common hematogenous metastasis to stomach ○ Ulceration of mucosa over intramural mets bull's-eye or "target" appearance • Kaposi sarcoma ○ GI involvement in 50%, usually with skin lesions ○ Elevated lesions; submucosal defects (0.5-3.0 cm) ○ Often ulcerate: Bull's-eye or "target" lesions • Gastric lymphoma ○ More frequent in stomach than other GI sites 249

Stomach

Gastric Ulcer ○ 50% of cases are confined to stomach ○ Causes nodular or circumferential soft tissue density wall thickening

Artifactual

Demographics

• Barium precipitates ○ Resemble tiny ulcers; differentiated by lack of projection beyond wall ○ Absence of mucosal edema or radiating folds • "Stalactites" ○ Hanging droplets of barium (on anterior wall) ○ Differentiated by transient nature on double-contrast barium studies

• Age ○ Usually > 40 years old • Gender ○ M=F • Epidemiology ○ Benign (95%), malignant (5%) ○ Often multiple: 20-30% prevalence

PATHOLOGY General Features • Etiology ○ 2 major factors: H. pylori (60-80%) and NSAIDs (20%) ○ Other risk factors: Steroids, tobacco, alcohol, coffee, stress, reflux of bile, delayed gastric emptying ○ Less common etiologies – Zollinger-Ellison syndrome – Hyperparathyroidism – Cushing ulcer: Stress (especially from head injury) – Curling ulcer: Burns ○ Pathogenesis – Normal or decreased levels of gastric acid – Breakdown in mucosal defense by H. pylori or NSAID allows acid to erode mucosa • Genetics ○ Genetic syndromes – Multiple endocrine neoplasia type 1 (MEN1) – Systemic mastocytosis ○ Greater concordance in monozygotic twins ○ Increased incidence with blood type O • Need for further evaluation ○ Unequivocal benign gastric ulcers on double-contrast studies: No further testing may be needed ○ Equivocal gastric ulcers (mixed features of benign and malignant) – Endoscopy and biopsy to exclude malignancy – If endoscopy and biopsy show no cancer, follow-up with upper GI series until complete healing • Multiple ulcers ○ 80% are benign; most likely cause: NSAIDs

Gross Pathologic & Surgical Features

Natural History & Prognosis • Complications ○ Hemorrhage, perforation, obstruction, and fistula • Prognosis ○ Good with medical treatment and surgery

Treatment • Ulcer without H. pylori: H2-receptor antagonists (cimetidine, ranitidine, or famotidine) or proton-pump inhibitors (omeprazole or lansoprazole) • H. pylori treatment: Metronidazole, bismuth plus clarithromycin, amoxicillin or tetracycline • Ulcer with H. pylori: H. pylori treatment and H2-receptor antagonists or proton-pump inhibitors • NSAID induced: Misoprostol and stop NSAIDs • Other agent: Sucralfate • Surgery required for ○ Recurrent or intractable ulcers ○ Ulcer complications ○ Equivocal or suspicious findings on radiologic or endoscopic examinations

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Benign gastric ulcers: Ulcer crater, Hampton line, ulcer mound and collar; smooth, radiating folds • Malignant gastric ulcers: Carman meniscus sign; nodular, blunted folds

SELECTED REFERENCES 1.

2.

• Round or oval; sharply punched-out and regular walls; flat adjacent mucosa

3.

Microscopic Features

4.

• Necrotic debris, zone of active inflammation, granulation and scar tissue

5.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic; may have anemia, GI blood loss ○ Burning, gnawing, or aching pain in epigastrium ○ Usually not relieved by food or antacids 250

○ Pain that awakens patients from sleep (33%) ○ Anorexia and weight loss (50%) • Diagnosis: Endoscopy with biopsy

Dib RA et al: Ulcer and bleeding complications and their relationship with dyspeptic symptoms in NSAIDs users: a transversal multicenter study. Scand J Gastroenterol. 49(7):785-9, 2014 Schroder VT et al: Vagotomy/drainage is superior to local oversew in patients who require emergency surgery for bleeding peptic ulcers. Ann Surg. 259(6):1111-8, 2014 Chen CY et al: MDCT for differentiation of category T1 and T2 malignant lesions from benign gastric ulcers. AJR Am J Roentgenol. 190(6):1505-11, 2008 Horton KM et al: Current role of CT in imaging of the stomach. Radiographics. 23(1):75-87, 2003 Insko EK et al: Benign and malignant lesions of the stomach: evaluation of CT criteria for differentiation. Radiology. 228(1):166-71, 2003

Gastric Ulcer Stomach

(Left) CECT of a penetrating gastric ulcer shows prominent folds along the greater curve and adjacent inflammatory changes in the mesenteric fat. Note the walled-off collection of fluid immediately adjacent to the stomach. (Right) Lateral view from an upper GI series in the same patient shows prominent gastric folds and an ulcer projecting off the greater curve. This corresponds to the site of focal fluid and inflammation seen on CT.

(Left) NECT of a perforated gastric ulcer shows a thickwalled stomach and massive free intraperitoneal gas . Extraluminal contrast material and gas are present near the anterior surface of the stomach , representing the perforated ulcer. (Right) In the same patient, the extravasated enteric contrast material mixes with ascites to result in high-attenuation ascites . Note that gastric ulcers may perforate into the lesser sac or the greater peritoneal cavity, as in this case.

(Left) NECT of an alcoholic man with pain and hypotension shows diffuse low attenuation of the liver, compatible with steatosis or massive hepatic necrosis. A nasogastric tube marks the dependent surface of the stomach. Contrast material spills into the lesser sac through a perforated ulcer. (Right) CT in the same patient shows the nasogastric tube and the lesser sac collection of oral contrast medium . The ulcer was confirmed and repaired at surgery, but the patient died of acute hepatic failure.

251

Stomach

Zollinger-Ellison Syndrome KEY FACTS

TERMINOLOGY

• Other gastritides

• Severe peptic ulcer disease associated with marked in gastric acid due to gastrin-producing endocrine tumor (gastrinoma) of pancreas

PATHOLOGY

IMAGING • Best diagnostic clue ○ Hypervascular pancreatic mass with multiple peptic ulcers and thickened folds • Best imaging tool ○ Helical CT or MR for pancreas and possible metastasis ○ Endoscopic ultrasonography for additional primary sites; guides biopsy

TOP DIFFERENTIAL DIAGNOSES • • • •

Helicobacter pylori gastritis Gastric carcinoma Gastric metastases and lymphoma Extrinsic inflammation

(Left) Axial CECT in a 63-yearold man who presented with intractable peptic ulcer disease demonstrates hyperemia and mural thickening of the stomach. (Right) Arterial phase CECT in the same patient shows a small hypervascular gastrinoma in the pancreatic head. It is important to distinguish this from the superior mesenteric artery and superior mesenteric vein .

(Left) Axial CT of a 55-year-old woman with hypercalcemia, diarrhea, and severe abdominal pain as presenting symptoms of MEN1 syndrome shows one of several neck masses , representing parathyroid adenomas or hyperplasia. (Right) Abdominal CT in the same case shows marked hypervascularity and thickening of the gastric wall . Multiple liver metastases are present . The serum gastrin levels were strikingly elevated, confirming ZES, though the gastrinoma was not identified on CT.

252

• 20-60% of cases are associated with multiple endocrine neoplasia type 1 (MEN1)

CLINICAL ISSUES • Most common signs/symptoms ○ Pain, increased acidity, severe reflux, diarrhea, upper gastrointestinal tract ulcers ○ Gastrinomas are often multiple (60%), malignant (60%), and metastatic (30-50%) • Hypergastrinemia is hallmark of Zollinger-Ellison syndrome (ZES) ○ Serum gastrin level of > 1,000 pg/mL is virtually diagnostic of ZES • Prognosis ○ Good with surgical resection of primary gastrinoma ○ Poor if gastrinoma, liver metastases, or ulcers recur after surgery

Zollinger-Ellison Syndrome

Abbreviations • Zollinger-Ellison syndrome (ZES)

Definitions • Severe peptic ulcer disease associated with marked in gastric acid due to gastrin-producing endocrine tumor (gastrinoma) of pancreas

IMAGING

Ultrasonographic Findings • Endoscopic ultrasonography (EUS) ○ Detects small gastrinomas better than CT or MR ○ Usually homogeneously hypoechoic mass • Intraoperative ultrasonography ○ Detects very small tumors (75-100% sensitivity)

Stomach

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Helical CT or MR for pancreas and possible metastasis ○ EUS for additional primary sites; guides biopsy

General Features • Best diagnostic clue ○ Hypervascular pancreatic mass with multiple peptic ulcers and thickened folds • Location ○ Gastrinoma: Pancreas (75%), duodenum (15%), and liver and ovaries (10%) – Common site: Gastrinoma triangle □ Superiorly: Cystic and common bile ducts □ Inferiorly: 2nd and 3rd parts of duodenum □ Medially: Junction of pancreatic neck and body ○ Ulcers: Stomach and duodenal bulb (75%), postbulbar and jejunum (25%)

Radiographic Findings • Barium studies: Gastric, duodenal, and proximal jejunum ○ Large volume of fluid dilutes barium and compromises mucosal coating ○ Markedly thickened gastric folds ○ Peptic ulcers: Round or ovoid barium collections surrounded by thin or thick radiolucent rim (edematous mucosa) and radiating folds

CT Findings • Gastrinomas ○ Small or large, heterogeneous density lesion, ± cystic and necrotic areas, ± calcification ○ Liver metastases are common ○ Hypervascular (primary and secondary) lesions ± local or vascular invasion on arterial and portal venous phase ○ Inflammatory changes in stomach, duodenum, and proximal small bowel – Thickened gastric, duodenal, and jejunal folds ○ Signs of ulcer penetration – Wall thickening, luminal narrowing of stomach and duodenum ○ Signs of ulcer perforation – Free air in abdomen (from a duodenal or antral ulcer) or lesser sac (from a gastric ulcer)

MR Findings • T1WI ○ Hypointense pancreatic nodule on fat-saturated sequence • T2WI ○ Hyperintense on spin-echo sequence – Both primary and metastatic tumors • T1WI C+ ○ Hyperintense, hypervascular on fat-saturated delayed spin-echo sequence

DIFFERENTIAL DIAGNOSIS Gastritis • Due to Helicobacter pylori, NSAIDs, etc. • Gastric antrum is most common site • Double-contrast barium findings ○ Thickened gastric folds ○ Enlarged areae gastricae ( 3 mm in diameter) • CT findings ○ Circumferential antral wall thickening with submucosal edema • Barium and CT findings may mimic ZES • Diagnosis: Endoscopic biopsy, culture, urea breath test

Gastric Carcinoma • Double-contrast barium findings ○ Early gastric cancer – Superficial lesion: Mucosal nodularity, ulceration, plaque-like or localized thickened gastric folds – Indistinguishable from focal peptic ulcers of ZES • CT findings ○ Gastric carcinoma usually narrows the lumen, thickens the wall with submucosal soft tissue (not water) density ○ Early gastric cancer – Focal wall thickening with mucosal irregularity – May simulate focal peptic ulcer disease of ZES • Diagnosis: Endoscopic biopsy and histology

Gastric Metastases and Lymphoma • Gastric metastases: Most common organs of origin ○ Malignant melanoma, breast, lung, colon, pancreas • Gastric lymphoma ○ Stomach is most frequently involved organ in gastrointestinal (GI) tract ○ Majority are non-Hodgkin lymphoma (B cell) • Barium findings ○ Malignant melanoma: Bull's-eye or "target" lesions – Centrally ulcerated submucosal masses ○ Breast cancer metastases – Linitis plastica or "leather bottle" appearance □ Loss of distensibility of antrum and body with thickened irregular folds – Mucosal nodularity, ulceration, and spiculation simulate peptic ulcers of ZES ○ Gastric lymphoma – Diffusely thickened irregular folds, discrete ulcers, ulcerated submucosal masses – Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma: Confluent, variably sized nodules 253

Stomach

Zollinger-Ellison Syndrome

• Pancreatitis • Thickened gastric wall can mimic ZES

○ M>F • Epidemiology ○ Rare compared to tumors of exocrine pancreas ○ Accounts for 0.1-1% of pancreatic tumors ○ Gastrinomas are 2nd most common functioning pancreatic endocrine tumors after insulinomas ○ Gastrinomas are often multiple (60%), malignant (60%), and metastatic (30-50%)

Other Gastritides

Natural History & Prognosis

• Crohn disease, eosinophilic gastritides • Early gastric Crohn disease: Multiple aphthous ulcers • Eosinophilic: Mucosal nodularity, thickened folds

• Prognosis ○ Good with surgical resection of primary gastrinoma ○ Poor if gastrinoma, liver metastases, or ulcers recur after surgery • Complications ○ Gastrinoma: risk of malignancy, metastases ○ Perforation of peptic ulcer

• CT findings ○ Markedly thickened gastric wall and mucosal folds ○ Bull's-eye, "target," or giant cavitated lesions ○ Thickened gastric folds and ulcers may simulate ZES

Extrinsic Inflammation

PATHOLOGY General Features • Etiology ○ Islet cell tumors are neuroendocrine tumors ○ Usually due to non- islet cell tumor (gastrinoma) of pancreas ○ Gastrinomas arise from amine precursor uptake and decarboxylation (APUD) cells of islet of Langerhans ○ Pathogenesis – Gastrinoma: gastrin levels gastric acid secretions peptic ulcers • Associated abnormalities ○ 20-60% of cases are associated with multiple endocrine neoplasia type 1 (MEN1) – MEN1: Tumors of pituitary, parathyroid, adrenal cortex, and pancreas • Embryology/anatomy ○ Islet cell tumor: Originates from embryonic neuroectoderm

Treatment • Medical: Protein pump inhibitors to treat gastric ulcers • Surgical: Gastrinoma resection • Liver metastases: Chemotherapy and hepatic artery embolization

DIAGNOSTIC CHECKLIST Consider • Ruling out other causes of gastric wall thickening and ulceration • MEN1 syndrome

Image Interpretation Pearls • Hypervascular pancreatic tumor, liver metastases with multiple ulcers and thickened folds of stomach, duodenum, and jejunum

Gross Pathologic & Surgical Features • Tumors: Encapsulated and firm; may be cystic, necrotic, with calcifications

Microscopic Features • Gastrinoma: Sheets of small round cells with uniform nuclei and cytoplasm • Ulcers: Necrotic debris, zone of granulation tissue

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pain, increased acidity, severe reflux, diarrhea, upper GI tract ulcers • Lab data: Secretin injection test ○ Paradoxical increase in serum gastrin to > 200 pg/mL above base levels in 90% of cases • Diagnosis ○ Gastrinoma and peptic ulcers on imaging ○ Hypergastrinemia is hallmark of ZES – Serum gastrin level of > 1,000 pg/mL is virtually diagnostic of ZES

Demographics • Age ○ Any age group but more common in 4th-5th decade • Gender 254

SELECTED REFERENCES 1.

Epelboym I et al: Zollinger-Ellison syndrome: classical considerations and current controversies. Oncologist. 19(1):44-50, 2014 2. Krampitz GW et al: Current management of the Zollinger-Ellison syndrome. Adv Surg. 47:59-79, 2013 3. Metz DC et al: Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors. Gastroenterology. 135(5):1469-92, 2008 4. Klose KJ et al: Localisation and staging of gastrin producing tumours using cross-sectional imaging modalities. Wien Klin Wochenschr. 119(19-20):58892, 2007 5. Levy AD et al: From the archives of the AFIP: Gastrointestinal carcinoids: imaging features with clinicopathologic comparison. Radiographics. 27(1):237-57, 2007 6. Levy AD et al: Duodenal carcinoids: imaging features with clinical-pathologic comparison. Radiology. 237(3):967-72, 2005 7. Pfannenberg AC et al: Dual-phase multidetector thin-section CT in detecting duodenal gastrinoma. Abdom Imaging. 30(5):543-7, 2005 8. Nino-Murcia M et al: Multidetector-row CT and volumetric imaging of pancreatic neoplasms. Gastroenterol Clin North Am. 31(3):881-96, 2002 9. Oshikawa O et al: Dynamic sonography of pancreatic tumors: comparison with dynamic CT. AJR Am J Roentgenol. 178(5):1133-7, 2002 10. Rodallec M et al: Helical CT of pancreatic endocrine tumors. J Comput Assist Tomogr. 26(5):728-33, 2002 11. Sheth S et al: Helical CT of islet cell tumors of the pancreas: typical and atypical manifestations. AJR Am J Roentgenol. 179(3):725-30, 2002

Zollinger-Ellison Syndrome Stomach

(Left) Upper GI series film shows a large jejunal ulcer resulting in a dilated duodenum due to spasm and edema. Gastric folds are thickened and the barium within the stomach is diluted and poorly adherent due to increased secretions. These are classic fluoroscopic features of ZES. (Right) EUS in the same patient shows a mass that was biopsied during the same procedure. The biopsy needle is evident . This documented a gastrinoma, accounting for the patient's signs and symptoms.

(Left) CECT in a 66-year-old man with ZES shows the gastrinoma as a small mass with an enhancing, solid periphery and a cystic or necrotic center. (Right) EUS in the same patient shows the mass (cursors) more clearly as having a cystic or necrotic center with a solid peripheral rim of tissue. EUS-guided biopsy proved this to be a benign gastrinoma.

(Left) Upper GI series in a 51year-old woman with a prior gastrectomy for peptic ulcer disease, now presenting with recurrent pain, shows a marginal ulcer at the site of the gastroenteric anastomosis. Note the radiating folds leading to the ulcer crater. (Right) Upper GI series in the same patient again shows the marginal ulcer and the radiating folds leading to the ulcer crater.

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Stomach

Ménétrier Disease KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Hyperplastic gastropathy, protein-losing gastropathy

• Bimodal age distribution ○ Children (usually boys) ○ Has been associated with cytomegalovirus infection • Adults, usually men (mean age: 55 years) ○ Prolonged and progressive illness in most adults • Complications ○ Gastric carcinoma may have prevalence (controversial) ○ Increased risk of deep venous thrombosis (DVT) ○ Risk of atrophic gastritis, gastric ulcer, GI bleeding • Treatment ○ Medical therapy: Anticholinergic agents, antibiotics, prostaglandins, octreotide – Monoclonal antibody (cetuximab), to EGFR – High-protein diet ○ May require total gastrectomy

IMAGING • Rare condition of unknown cause • Upper GI series: Grossly thickened, lobulated folds in gastric fundus and body with poor barium coating • CECT: Massive thickening of mucosa and submucosa ○ Engorged gastric arteries and veins ○ No extension into perigastric tissues • Histology: Marked foveolar hyperplasia (mucin production) ○ Leads to protein loss and hypoproteinemia ○ Atrophy of acid-producing cells hypochlorhydria

TOP DIFFERENTIAL DIAGNOSES • • • •

Gastritis Zollinger-Ellison syndrome Gastric metastases and lymphoma Gastric carcinoma

(Left) Film from an upper GI series shows massive fold thickening throughout the gastric fundus and body, with relative sparing of the antrum. Also noted is poor coating of the mucosa by the barium. (Right) CECT in a 68-year-old woman with proven Ménétrier disease, shows grossly thickened folds in the gastric fundus and body, along with engorged gastric vessels . The thick, tortuous folds resemble cerebral convolutions.

(Left) Film from an upper GI series shows massive fold thickening of the gastric fundus and body, with sparing of the antrum. Note the poor coating of the gastric mucosa with barium to the surface of the stomach, reflecting the excessive mucus discharge of the gastric glands. (Right) In the same patient, CECT shows marked thickening of the gastric mucosa and submucosa , but there is no sign of extension into the perigastric tissues. The gastric arterial and venous branches are engorged , indicating hyperemia of the stomach.

256

Ménétrier Disease

PATHOLOGY

Synonyms

General Features

• Hyperplastic gastropathy, protein-losing gastropathy

• Etiology ○ Unknown ○ Mucosal thickening (massive foveolar hyperplasia) • Associated abnormalities ○ Generalized signs of edema, hypoproteinemia (e.g., ascites, pleural effusion)

Definitions • Rare acquired condition characterized by hyperproliferative protein-losing gastropathy of gastric foveolar epithelium

IMAGING General Features • Best diagnostic clue ○ Grossly thickened, lobulated folds in gastric fundus and body with poor barium coating • Other general features ○ Rare condition of unknown cause ○ Characterized by – Enlarged, tortuous gastric rugal folds – Marked foveolar hyperplasia (mucin production) □ Hypoproteinemia: Protein loss – Hypochlorhydria (HCL output in 75% of cases)

Radiographic Findings • Upper GI series ○ Grossly thickened, lobulated folds in gastric fundus and body with relative sparing of antrum ○ May show thickened gastric folds even in antrum ○ Focal area of rugal hypertrophy on greater curvature ○ Giant, mass-like, tortuous folds resemble cerebral convolutions ○ Stomach remains pliable and distensible ○ Excess mucus may dilute barium and mucosal coating

CT Findings • Massive thickening of mucosa and submucosa • Engorged gastric arteries and veins • No extension into perigastric tissues

DIFFERENTIAL DIAGNOSIS Gastritis • From other causes, such as Helicobacter pylori • Thickened, lobulated folds favor antrum • Diagnosis: Endoscopic biopsy, culture, urease test

Zollinger-Ellison Syndrome • Also causes thick folds and increased fluid in stomach • Multiple ulcers, pancreatic tumor (gastrinoma) are not found in Ménétrier

Gastric Metastases and Lymphoma • • • •

Thickened gastric folds similar to Ménétrier No excess fluid in stomach Submucosal soft tissue rather than edema Associated extragastric tumor or nodes

Gastric Carcinoma • More often causes large discrete mass • Diffuse infiltration limits distensibility • Submucosal soft tissue density tumor (not edema)

Stomach

TERMINOLOGY

Gross Pathologic & Surgical Features • Large, thickened, tortuous gastric mucosal folds • Mucosal inflammation

Microscopic Features • Cystic dilatation, elongated gastric mucous glands • Massive in foveolar mucin-producing cells • Atrophy and number of chief and parietal cells ( decreased acid production)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Epigastric pain, vomiting, diarrhea, weight loss ○ Occasionally peripheral edema (hypoproteinemia) • Lab: albumin, or absent HCL, ± fecal occult blood • Diagnosis: Endoscopic full thickness biopsy

Demographics • Age ○ Bimodal age distribution – Children (usually boys) □ Has been associated with cytomegalovirus infection □ Relatively mild and self-limited disease – Adults (mean age: 55 years); M > F • Epidemiology ○ Rare (< 1 in 200,000 people)

Natural History & Prognosis • Complications ○ Gastric carcinoma may have prevalence (controversial) ○ risk of deep venous thrombosis ○ Risk of atrophic gastritis, gastric ulcer, GI bleeding • Prognosis ○ Prolonged and progressive illness in most adults ○ Children may have spontaneous remission

Treatment • Medical therapy: Anticholinergic agents, antibiotics, proton pump inhibitors ○ Octreotide (somatostatin analog) ○ High-protein diet ○ Monoclonal antibody (cetuximab) to epidermal growth factor receptor (EGFR) • Total gastrectomy (unresponsive cases)

SELECTED REFERENCES 1.

Fiori R et al: Ménétrier's disease diagnosed by enteroclysis CT: a case report and review of the literature. Abdom Imaging. 36(6):689-93, 2011

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Stomach

Caustic Gastroduodenal Injury KEY FACTS

TERMINOLOGY • Gastroduodenal inflammation/injury due to acid or alkali

IMAGING • Massive submucosal edema of esophagus and stomach on CT, with appropriate history of corrosive ingestion • Esophagus is organ most often injured ○ Classically damaged by strong alkaline agents • Gastroduodenal injury is next most common ○ Most likely to be damaged by strong acids • Acute: Mild to moderate severity ○ Gastric and esophageal, ± duodenal submucosal edema ○ Best evaluated by CECT ○ Caustic agents cause intense pylorospasm, so duodenal injury is less common • Acute: Severe ○ Pneumoperitoneum (perforation) • Chronic phase ○ Gastric outlet obstruction (antral scarring and fibrosis)

(Left) Axial NECT shows tremendous thickening of the wall of the stomach and ascites. These findings suggest transmural inflammation and a high likelihood of subsequent necrosis and perforation of the stomach. (Right) Axial NECT of the same patient shows diffuse involvement of the entire stomach . The patient subsequently had gastric perforation and died.

(Left) Upright film from an upper GI series in a 24-year-old man who drank drain cleaner several days prior shows delayed gastric emptying with fluid levels . Note the fixed contraction (linitis plastica) of the body and antrum of the stomach . (Right) Film from an upper GI series in a 56-yearold man who drank acid several weeks prior demonstrates a linitis plastica appearance of the stomach being small, rigid, nondistensible, and without peristalsis.

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○ Linitis plastica: Small, aperistaltic stomach with effaced folds ○ Best evaluated by upper GI series

TOP DIFFERENTIAL DIAGNOSES • Gastric carcinoma (scirrhous type) • Gastric metastases and lymphoma • Gastric thermal injury (iced saline)

CLINICAL ISSUES • Prognosis ○ Acute mild phase with early treatment: Good ○ Acute severe and chronic phases: Poor • Treatment ○ Conservative treatment for stable patients – Antibiotics, steroids, parenteral feedings ○ Gastric outlet obstruction – Gastroenterostomy or partial gastrectomy – Complete gastrectomy with colonic interposition

Gastroparesis

TERMINOLOGY • Objectively delayed gastric emptying in absence of mechanical obstruction

IMAGING • Best test: Delayed emptying of both solids and liquids on radionuclide gastric emptying scan • Upper GI series or CT ○ Dilated stomach with decreased or absent peristalsis

TOP DIFFERENTIAL DIAGNOSES • Gastric outlet obstruction • Postoperative state, stomach

PATHOLOGY • Idiopathic: No identifiable cause in ~ 50% of cases • Type 1 diabetes is main identifiable cause ○ Usually longstanding and poorly controlled ○ Affects 40% of patients with diabetes

• Narcotic analgesics are 3rd most common cause ○ Others drugs may also be implicated • Postsurgical ○ Prior thoracic or gastric surgery may injure vagus nerve ○ Some cases are deliberate – e.g., to reduce gastric acid production ○ Other cases are unintentional – e.g., following fundoplication • Neurologic disorders • Electrolyte disturbances

Stomach

KEY FACTS

CLINICAL ISSUES • Symptoms ○ Nausea, vomiting, postprandial bloating, early satiety are all common • Treatment ○ Promotility and antiemetic agents ○ Botulinum toxin injection into gastric pylorus ○ Gastric electrical stimulation device

(Left) Upper GI series of a 34year-old man with type 1 diabetes and persistent nausea shows stasis of the barium (after a 20 minute delay) and food debris within the stomach, in spite of no oral intake for > 12 hours. No peristalsis was evident. (Right) NECT in a 61-year-old man with diabetes shows a markedly distended stomach containing contrast material and food in spite of the patient having fasted for 12 hours. This indicates delayed gastric emptying and proved to be due to diabetic gastroparesis.

(Left) Gastric emptying scintigraphy in a patient with diabetic gastroparesis shows mild to moderate gastric emptying delay (30% emptied at 120 minutes, 55% at 240 minutes) on this solid-labeled phase. Similar delay was found for liquids. (Right) Gastric emptying scan shows severe delay in emptying of ingested solids (32% at 120 minutes). This patient had multiple prior surgeries, including vagotomy and Billroth II partial gastrectomy. Multiple factors most likely contribute to delayed emptying in this patient.

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Stomach

Gastric Bezoar KEY FACTS

TERMINOLOGY

PATHOLOGY

• Intragastric mass composed of accumulated ingested (but not digested) material ○ Phytobezoar: Undigested vegetable matter – Persimmons contain tannin, which coagulates on contact with gastric acid ○ Trichobezoars: Accumulated, matted mass of hair – Most common in young girls ○ Lactobezoar: Undigested milk concretions (infants) ○ Pharmacobezoar: Bezoar composed of medications

• Predisposing causes ○ Previous gastric surgery: Vagotomy, pyloroplasty, antrectomy, partial gastrectomy ○ Inadequate chewing, missing teeth, dentures ○ Overindulgence in foods with high fiber content ○ Altered gastric motility: Diabetes, mixed connective tissue disease, hypothyroidism

IMAGING • Mobile intraluminal gastric filling defect • "Mottled" appearance is result of air bubbles retained in interstices of mass • Large bezoars may fill and take shape of stomach • Small bezoars are rounded or ovoid ○ Tend to float on water-air surface surrounded by gastric contents

(Left) Film from an upper GI series in a 60-year-old man with early satiety years after vagotomy and Billroth 1 surgery shows evidence of the prior surgery and a large heterogeneous "ball" of debris and gas within the stomach mixed with the barium. (Right) Axial CECT shows a laminated mass in the stomach due to a phytobezoar.

(Left) Upper GI series in a 3year-old girl with vomiting shows a fixed filling defect in the stomach with a swirled pattern of gas and solid material found to represent a trichobezoar. (Right) A film from a small bowel followthrough shows evidence of a prior Billroth II partial gastrectomy and complete obstruction of antegrade flow of barium in the mid jejunum. At surgery, a phytobezoar was removed, which corresponded to the shape and size of the gastric remnant.

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CLINICAL ISSUES • Bezoars usually form in stomach ○ May fragment and enter small bowel where they absorb water, increase in size, and become impacted ○ May present with small-bowel obstruction • Drinking several liters of cola beverage has been reported to clear all or portions of phytobezoars • Symptomatic, large phytobezoars or trichobezoars require endoscopic fragmentation or surgical removal ○ Spontaneous expulsion of bezoar is uncommon

Gastric Bezoar

PATHOLOGY

Definitions

General Features

• Intragastric mass composed of accumulated ingested (but not digested) material

• Etiology ○ Ingested material unable to exit stomach – Accumulated due to large size, indigestibility, gastric outlet obstruction, poor gastric motility ○ Phytobezoar: Unripe persimmons, oranges – Persimmons contain tannin, which coagulates on contact with gastric acid – Glue-like coagulum forms, trapping seeds, skin, etc. ○ Trichobezoars: Accumulated, matted mass of hair – Most common in girls who chew on ends of their hair • Associated abnormalities ○ Concurrent gastric bezoar found in 17-53% of patients with small-bowel bezoar • Predisposing causes ○ Previous gastric surgery: Vagotomy, pyloroplasty, antrectomy, partial gastrectomy ○ Inadequate chewing, missing teeth, dentures ○ Overindulgence in foods with high fiber content ○ Altered gastric motility: Diabetes, mixed connective tissue disease, hypothyroidism

IMAGING General Features • Best diagnostic clue ○ CT or fluoroscopy: Intraluminal mass containing mottled air pattern • Location ○ Sites of impaction: Stomach, jejunum, ileum – Any part can be affected, especially in patients with postoperative adhesions • Morphology ○ Large bezoars fill and take shape of stomach

Fluoroscopic Findings • Intraluminal filling defect ○ Freely mobile, without constant site of attachment to bowel wall • Barium outlines bezoar ○ "Mottled" or streaked appearance; contrast medium entering interstices of bezoar • Partial or complete small bowel obstruction ○ Try to distinguish obstruction due to postoperative adhesions from bezoar-induced obstruction

CT Findings • Well-defined, oval, low-density, intraluminal mass ○ "Mottled" appearance of mass is due to air bubbles retained in interstices of mass • Large bezoars tend to fill lumen • Small bezoars are rounded or ovoid; tend to float on waterair surface surrounded by gastric contents ○ Oral contrast material may be seen surrounding mass, establishing free intraluminal location • Bezoar may have "laminated" appearance

Imaging Recommendations • Best imaging tool ○ CT: More accurate in confirming diagnosis of gastric bezoar suggested by other modalities – Diagnose bezoar-induced bowel obstruction

DIFFERENTIAL DIAGNOSIS Gastric Carcinoma • Filling defect in stomach; polypoid or fungating

Postprandial Food • Fluoroscopy: Intraluminal filling defect • Occasionally difficult to differentiate bezoar from large amount of retained food

Intramural Mass • Stromal tumor (GIST), lymphoma, melanoma metastases

Stomach

TERMINOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic; incidentally found on imaging ○ Anorexia, bloating, early satiety ○ Crampy epigastric pain ○ Sense of dragging, heaviness in upper abdomen ○ May present with small bowel obstruction • In adults, bezoars are most frequently encountered after gastric operation ○ In children, associated with pica, mental retardation, coexistent psychiatric disorders • Trichobezoars seen especially in those with schizophrenia or other mental instability ○ Primarily girls who chew and swallow their own hair • Lactobezoar most often found in infants ○ Preterm infants on calorie-dense formulas ○ Immature mechanism of gastric emptying

Treatment • Symptomatic, large phytobezoars or trichobezoars require endoscopic fragmentation or surgical removal • Spontaneous expulsion of bezoar is uncommon

SELECTED REFERENCES 1. 2.

3. 4.

Altintoprak F et al: CT findings of patients with small bowel obstruction due to bezoar: a descriptive study. ScientificWorldJournal. 2013:298392, 2013 Tudor EC et al: Laparoscopic-assisted removal of gastric trichobezoar; a novel technique to reduce operative complications and time. J Pediatr Surg. 48(3):e13-5, 2013 Zildzic M et al: The large gastric trichobezoar associated with ulcers and antral polyposis: case report. Med Arch. 67(3):212-4, 2013 Dirican A et al: Surgical treatment of phytobezoars causes acute small intestinal obstruction. Bratisl Lek Listy. 110(3):158-61, 2009

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Stomach

Gastric Volvulus KEY FACTS

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Organoaxial volvulus: Rotation of stomach around its long axis ○ Most common type; "upside-down stomach" ○ Occurs in setting of large paraesophageal hernia ○ Stomach rotates upward, with greater curvature lying above lesser curve • Mesenteroaxial volvulus: Rotation of stomach about its short axis ○ More common type in children • Entire stomach may be herniated (type IV paraesophageal hernia [PEH]) or only part (type III PEH) ○ Either can result in volvulus ± obstruction ± ischemia ○ Gastric wall pneumatosis indicates ischemia • Diagnosed with upper GI &/or CT • CT is better at demonstrating associated hernias and gastric ischemia

• Hiatal hernia ○ Types III and IV PEHs increase risk for gastric volvulus • Postoperative state, stomach ○ Esophagectomy with gastric pull through (conduit may twist and obstruct) • Epiphrenic diverticulum

(Left) Graphic illustrates an organoaxial gastric volvulus, in which the stomach twists along its long axis, resulting in the greater curvature (GC) lying above the lesser curvature (LC). (Right) Film from an upper GI series in a 73-year-old woman shows a type IV paraesophageal hernia (PEH) with organoaxial volvulus but little or no obstruction. The greater curvature of the stomach lies above the lesser curvature. The small bowel is also herniated through a large diaphragmatic defect.

(Left) Axial CECT demonstrates an intrathoracic stomach (type IV PEH) in a 81year-old woman with mild chest pain and a known brain malignancy. The stomach is dilated with 2 air-fluid levels, indicating obstruction. (Right) Coronal CECT in the same patient demonstrates an "upside-down" configuration of the stomach, with reversal of the greater and lesser curvatures, in keeping with an organoaxial volvulus.

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CLINICAL ISSUES • Treatment: Open or laparoscopic detorsion and gastropexy

DIAGNOSTIC CHECKLIST • Presence or absence of obstruction and ischemia are more important than remembering or reporting whether volvulus is organo- or mesenteroaxial

Gastric Volvulus

Abbreviations • Gastric volvulus

Definitions • Uncommon acquired twist of stomach on itself

IMAGING General Features • Morphology ○ Abnormal degree of rotation of 1 part of stomach around another part • Types of volvulus: Organoaxial (most common), mesenteroaxial, mixed • Organoaxial volvulus: Rotation of stomach around its longitudinal axis ○ Around line extending from cardia to pylorus ○ Stomach rotates upward, with greater curvature lying above lesser curvature ○ Antrum moves from inferior to superior position; fundus rotates superior to inferior ○ Usual setting is with a large paraesophageal hernia (PEH) – Type III PEH = Gastroesophageal (GE) junction and portions of fundus and body herniate into chest – Type IV PEH = GE junction and almost entire stomach lie within chest • Mesenteroaxial volvulus: Rotation of stomach about its mesenteric (short) axis ○ Axis running transversely across stomach at right angles to lesser and greater curvatures ○ Stomach rotates from right to left, or left to right about long axis of gastrohepatic omentum ○ Not necessarily in setting of hiatal hernia ○ May result from congenital absence or laxity of gastric ligaments • Mixed volvulus: Combination of organoaxial and mesenteroaxial volvulus

Radiographic Findings • Radiography ○ Abdominal plain films; patient upright – Double air-fluid level – Large, distended stomach; seen as air- and fluid-filled spheric viscus displaced upward and to left – Small bowel collapsed if stomach is obstructed ○ Chest film: Intrathoracic; upside-down stomach – Retrocardiac fluid level; 2 air-fluid interfaces at different heights; suggests intrathoracic gastric volvulus

Fluoroscopic Findings • Upper GI ○ Massively distended stomach in left upper quadrant extending into chest ○ Inversion of stomach (upside-down stomach) – Greater curvature above level of lesser curvature – Positioning of cardia and pylorus at same level – Downward pointing of pylorus and duodenum ○ Volvulus with > 180° twist causes luminal obstruction

○ Incomplete or absent entrance of contrast material into &/or out of stomach; acute obstructive volvulus ○ May see "beaking" at point of twist ○ Mesenteroaxial: Antrum and pylorus lie above gastric fundus

Stomach

TERMINOLOGY

CT Findings • CT appearance may be variable ○ Depends upon extent of gastric herniation, points of torsion and final positioning of stomach ○ May see linear septum within gastric lumen; corresponding to area of torsion • Entire stomach may be herniated (type IV PEH) or only part (type III PEH) ○ Either can result in volvulus ± obstruction ± ischemia ○ Ischemia seen as lack of contrast enhancement of gastric wall ± pneumatosis within wall • CT chest and abdomen; performed preoperatively ○ To detect associated malformation or malposition and site, size, level of diaphragmatic defect

Imaging Recommendations • Best imaging tool ○ Upper GI series – Demonstrates focus of twist; anatomic detail ○ Fluoroscopic guidance may help in advancing nasogastric tube into obstructed stomach – May allow decompression and stabilization of patient ○ CT: Complementary role – Multiplanar reformations help depict altered anatomy – CT is better at diagnosing gastric ischemia

DIFFERENTIAL DIAGNOSIS Hiatal Hernia • Stomach entering thorax through esophageal hiatus • Type I: "Sliding"; GE junction and cardia above diaphragm • Type II: Herniation of fundus through hiatus; GE junction below diaphragm (rare) • Type III: Most common type of paraesophageal hernia; GE junction and fundus ± body of stomach in chest • Type IV: Intrathoracic stomach; GE junction and most of stomach in chest • Type III and IV paraesophageal hernias predispose to volvulus

Postoperative State, Stomach • Esophagectomy with gastric pull-through procedure • Complete mobilization of stomach, resection of lower esophagus, pyloroplasty, transhiatal dissection ○ Intrathoracic stomach is the intended result ○ Conduit can twist (volvulus) with outlet obstruction

Epiphrenic Diverticulum • Large pulsion diverticulum above diaphragm • May have an air-fluid level

PATHOLOGY General Features • Etiology 263

Stomach

Gastric Volvulus ○ Stabilizing ligaments are too lax as result of congenital or acquired causes ○ Congenital Morgagni or Bochdalek hernia – May lead to gastric volvulus in children or adults ○ Traumatic diaphragmatic rupture with gastric herniation • Associated abnormalities ○ Large paraesophageal hernia – Permits part or all of stomach to enter chest ○ Diaphragmatic eventration or paralysis – Could result in volvulus of intraabdominal stomach (rare) ○ Wandering spleen: Absence of ligamentous connections between stomach, spleen ○ Hernia of colonic transverse loop ± other bowel loops – Invariably through very large diaphragmatic defect

Gross Pathologic & Surgical Features • Herniated and twisted stomach • May or may not be ischemic ○ Complete obstruction often leads to ischemia and perforation if not corrected

CLINICAL ISSUES Presentation • Gastric volvulus can be asymptomatic if there is no outlet obstruction or vascular compromise ○ May be an incidental finding on imaging ○ Patients usually endorse symptoms of GE reflux, if asked • Acute volvulus; associated interference of blood supply ○ Surgical emergency ○ Classic clinical triad (Borchardt triad) – Violent retching with production of little vomitus – Constant severe epigastric pain – Difficulty in advancing nasogastric (NG) tube beyond distal esophagus • Chronic or intermittent gastric volvulus ○ Frequently not recognized early in its presentation ○ Vague and nonspecific symptoms suggestive of other abdominal processes, causing delay in diagnosis – Volvulus may be inadvertently reduced by placement of NG tube prior to imaging, precluding diagnosis

Demographics • Age ○ Mesenteroaxial is most common type in children – Associated anatomic defects are usually found ○ Organoaxial accounts for over 60% of adult cases; only 40% of pediatric cases – More common in elderly

Natural History & Prognosis • As hernias enlarge, body and variable portion of antrum come to lie above diaphragm ○ Stomach can become entirely intrathoracic organ; prone to volvulus • Obstruction can occur at points of torsion or at points where stomach reenters abdomen through hiatus ○ As much as 180° of twisting may occur without obstruction or strangulation ○ Twisting beyond 180° usually produces complete obstruction and clinically acute abdomen 264

○ Organoaxial: Can obstruct; does not usually result in strangulation – Mesenteroaxial: Can occlude gastric vessels; strangulation Upside-down stomach ○ Usually constitutes organoaxial volvulus ± obstruction ○ Presents with bleeding and anemia; uncommonly induces obstruction or strangulation Vascular occlusion leads to necrosis, shock Strangulation may lead to mucosal ischemia and perforation ○ Areas of focal necrosis; may permit gas to dissect into gastric wall Prognosis: gastric volvulus is potentially a catastrophic condition ○ Mortality rate: 30% when obstruction is present

•

• •

•

Treatment • Open or laparoscopic detorsion and gastropexy • Gastric resection for strangulation and necrosis • Upside-down stomach: Balloon repositioning; fixation by percutaneous endoscopic gastrostomy

DIAGNOSTIC CHECKLIST Consider • Anatomical detail of stomach often better delineated on upper gastrointestinal studies ○ Identification of gastric volvulus can be incidental finding on CT – Consider whenever stomach is noted to be in abnormal anatomic position

Image Interpretation Pearls • Presence or absence of obstruction and ischemia are more important than remembering or reporting whether volvulus is organo- or mesenteroaxial

SELECTED REFERENCES 1.

Collet D et al: Management of large para-esophageal hiatal hernias. J Visc Surg. 150(6):395-402, 2013 2. Cross BN et al: Roux-en-Y gastric bypass in the setting of congenital malrotation: a report and review of the literature. Surg Obes Relat Dis. 9(6):e91-5, 2013 3. Toydemir T et al: Laparoscopic management of totally intra-thoracic stomach with chronic volvulus. World J Gastroenterol. 19(35):5848-54, 2013 4. Bawahab M et al: Management of acute paraesophageal hernia. Surg Endosc. 23(2):255-9, 2009 5. Chang CC et al: A surgical emergency due to an incarcerated paraesophageal hernia. Am J Emerg Med. 27(1):134, 2009 6. Gerstle JT et al: Gastric volvulus in children: lessons learned from delayed diagnoses. Semin Pediatr Surg. 18(2):98-103, 2009 7. Yano F et al: Outcomes of surgical treatment of intrathoracic stomach. Dis Esophagus. 22(3):284-8, 2009 8. Shivanand G et al: Gastric volvulus: acute and chronic presentation. Clin Imaging. 27(4):265-8, 2003 9. Tabo T et al: Balloon repositioning of intrathoracic upside-down stomach and fixation by percutaneous endoscopic gastrostomy. J Am Coll Surg. 197(5):868-71, 2003 10. Godshall D et al: Gastric volvulus: case report and review of the literature. J Emerg Med. 17(5):837-40, 1999

Gastric Volvulus Stomach

(Left) Frontal radiograph (not shown) in an elderly woman showed an intrathoracic stomach (type IV PEH). CT showed the esophagogastric junction in the chest. The pylorus also lies within the chest. (Right) More caudal CT section in the same patient shows a type IV PEH. The fundus lies lower than the antrum and pylorus. This could be considered organoaxial "position" versus "volvulus," and no obstruction is present.

(Left) Axial NECT in a 63-yearold woman with chronic intermittent chest and abdominal pain demonstrates the entirety of the stomach within the thoracic cavity (type IV PEH). Notice the large amount of contrast retained in the stomach nearly 2 hours after its administration. (Right) Axial NECT in the same patient again demonstrates the intrathoracic stomach with retained contrast in its lumen.

(Left) Coronal NECT in the same patient better demonstrates the twisting of the stomach, with the greater and lesser curvatures having reversed. (Right) Coronal NECT in the same patient demonstrates contrast retained within the midthoracic esophagus . The patient was felt to be at least partially obstructed, and underwent operative repair, where the organoaxial volvulus was confirmed.

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Stomach

Gastric Volvulus

(Left) Axial NECT in an 83year-old woman with chest pain demonstrates the entirety of the stomach located within the thorax, a type IV PEH. (Right) Coronal NECT in the same patient demonstrates the stomach twisted along its long axis, with the greater curvature above the lesser curvature, in keeping with an organoaxial volvulus.

(Left) Upright film from an upper GI series in an 80-yearold woman with symptoms only of reflux shows a dilated intrathoracic stomach (type IV PEH) with an organoaxial volvulus. The duodenal lumen is narrowed as it enters the abdomen. (Right) Upright film from an upper GI shows eventration or paralysis of the left diaphragm and an upsidedown stomach, another appearance of an organoaxial volvulus. Partial gastric outlet obstruction is evident by delayed passage of barium into the duodenum.

(Left) Graphic illustrates a mesenteroaxial volvulus in which the stomach twists along its short axis, resulting in the antrum (A) lying above the fundus and gastroesophageal (GE) junction. (Right) Spot film from an upper GI series shows the GE junction and fundus in the abdomen. The body and antrum of the stomach are in the chest and are twisted and compressed as they traverse the diaphragm, constituting a mesenteroaxial volvulus with obstruction.

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Gastric Volvulus Stomach

(Left) Supine film in an elderly woman with severe vomiting, retching, and hematemesis shows gas distention of an abnormal-appearing stomach and retrocardiac mass effect . (Right) Lateral supine scout digital radiograph in the same patient shows 2 air-fluid levels within the stomach , and the retrocardiac fluid-density mass .

(Left) CECT in the same patient shows a large type III PEH with fluid distention of the herniated stomach , along with pneumatosis in the gastric wall , indicating ischemic injury. (Right) Another CT image in the same case shows 2 separate air-fluid levels within the distended stomach, and additional evidence of gastric pneumatosis . The larger collection of gas and fluid is within the gastric body and antrum, which lie in the thorax, while the smaller collection is within the intraabdominal gastric fundus.

(Left) More caudal CT section in the same case shows pneumatosis within the gastric fundus . (Right) More caudal CT section in the same patient shows a gasless duodenum and small bowel due to the incarcerated gastric volvulus. Volvulus and gastric infarction were confirmed at surgery.

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Stomach

Iatrogenic Injury: Feeding Tubes KEY FACTS

TERMINOLOGY • Patient injury caused by improper feeding tube placement • Feeding tubes ○ Small, soft enteric tubes ○ Some with flexible metallic tips ○ Tip of feeding tube should be located beyond stomach (distal duodenum or jejunum) • Nasogastric tubes ○ Large-bore, moderately stiff ○ Used for temporary bowel decompression ○ Tip placed in pylorus can cause outlet obstruction • Gastrostomy and jejunostomy tubes ○ Balloon-tipped catheters should not be placed into small bowel (may obstruct lumen) ○ Small amount of free air after placement is common and usually does not require intervention

IMAGING • Malposition is most frequent complication of feeding tubes

(Left) Esophagram shows a retroesophageal collection of gas and contrast medium resulting from perforation of a Zenker diverticulum by attempted placement of a feeding tube whose track runs parallel to the proximal esophagus. (Right) Chest radiograph shows a feeding tube that has entered the right bronchus and perforated the lung though a lower lobe bronchus. The tip lies in the pleural space, a procedural complication that may be fatal, especially if food is given through the tube.

(Left) Frontal radiograph shows the peculiar course of the feeding tube with abrupt upper deviation of its distal portion. CT showed that the tube had perforated the duodenum and had been advanced with its wire in place. (Right) Axial CECT shows a feeding gastrostomy tube entering the stomach. The balloon tip of the tube has migrated into the jejunum where it is partially occluding its lumen.

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○ Can be visualized on chest or abdominal radiograph ○ Auscultation over abdomen is not reliable method for confirming proper tube placement

CLINICAL ISSUES • 1-3% of feeding tubes enter tracheobronchial tree ○ Anywhere from trachea to pleural space ○ Can perforate lung with significant morbidity and mortality • Tube may penetrate esophagus or duodenum with fatal results ○ Often through diverticula (e.g., Zenker), due to thin wall • High-risk patients ○ Altered mental status ○ Absent gag reflex ○ Multiple or repetitive insertion attempts • Treatment ○ Reposition feeding tube if in incorrect location ○ Perforation of lung or bowel may require surgery

Iatrogenic Injury: Feeding Tubes

Definitions • Patient injury caused by improper feeding tube placement • Feeding tubes ○ Small, soft enteric tubes ○ Some with flexible metallic tips ○ Used for feeding chronically ill patients ○ Can be used for long periods of time • Nasogastric tubes ○ Large-bore, moderately stiff ○ Used for temporary bowel decompression or fluid sampling ○ Tip placed in pylorus can cause gastric outlet obstruction • Gastrostomy and jejunostomy tubes ○ Placed surgically, endoscopically, or percutaneously ○ Used for long-term, possibly permanent, feeding ○ Use imaging to visualize tube balloon, surgical clips, and cuff – Cuff initiates soft tissue reaction to anchor tube to abdominal wall ○ PEG button can replace tube several weeks post placement – Placed in anterior abdominal wall ○ Balloon-tipped catheters should not be placed into small bowel – Likely to obstruct bowel lumen

IMAGING

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• •

•

CLINICAL ISSUES Presentation • Other signs/symptoms ○ Respiratory distress – Cough, dyspnea, cyanosis – Not always present ○ Aberrant pH of aspirate – Limited by use of proton-pump inhibitors

General Features

Demographics

• Best diagnostic clue ○ Malposition is most frequent complication of feeding tubes – Check on chest or abdominal radiograph ○ Usual course: Nares/mouth esophagus stomach small bowel • Location ○ Tip of feeding tube should be located beyond stomach – In distal duodenum or proximal jejunum

• Epidemiology ○ 1-3% of feeding tubes lodge in airways • High-risk patients ○ Altered mental status ○ Absent gag reflex ○ Multiple or repetitive insertion attempts

Imaging Recommendations • Best imaging tool ○ Chest or abdominal radiograph ○ Radiography is most accurate way to detect malposition/complications – Obtain chest film after initial placement, followed by abdominal film ○ Electromagnetically guided placement systems are also in use ○ Auscultation over abdomen is not reliable method for detecting proper tube placement

Radiographic Findings • Inadvertent placement in airways ○ Metal tip or stiffening wire can perforate lung ○ Administration of formula empyema • Malposition in esophagus ○ Can enter stomach and then coil back into esophagus • Aspiration of gastrointestinal contents

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○ Secondary to malposition in esophagus, pharynx, or stomach ○ Clue: Bilateral pulmonary infiltrates Perforation of gastrointestinal tract ○ Can perforate esophagus (e.g., Zenker diverticulum) or duodenum Gastrointestinal hemorrhage ○ May irritate and ulcerate mucosa Knotted tubing ○ Due to coiling, often within stomach ○ Can result in tube malfunction due to obstruction Complications of PEG tubes ○ Free intraperitoneal air – Usually does not require intervention ○ Injury to abdominal structures (liver, colon) ○ Gastrointestinal obstruction – Secondary to migration of balloon tip into pylorus or duodenum – Do not put Foley catheter through PEG tube track

TERMINOLOGY

Treatment • Reposition feeding tube if in incorrect location

DIAGNOSTIC CHECKLIST Consider • Radiographic confirmation is best way to ascertain proper tube position • Feeding tubes can move spontaneously ○ Position should be confirmed on each radiograph

SELECTED REFERENCES 1. 2. 3.

4.

5.

Ojo O: Problems with use of a Foley catheter in enteral tube feeding. Br J Nurs. 23(7):360-2, 364, 2014 Gor P: Placement of nasogastric tubes must be checked thoroughly. Nurs Stand. 27(43):32, 2013 Khasawneh FA et al: Nasopharyngeal perforation by a new electromagnetically visualised enteral feeding tube. BMJ Case Rep. 2013, 2013 Marco J et al: Bronchopulmonary complications associated to enteral nutrition devices in patients admitted to internal medicine departments. Rev Clin Esp (Barc). 213(5):223-8, 2013 Simons SR et al: Bedside assessment of enteral tube placement: aligning practice with evidence. Am J Nurs. 112(2):40-6; quiz 48, 47, 2012

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Partial Gastrectomy: Bilroth Procedures KEY FACTS

IMAGING • Billroth 1 (B1) procedure ○ Antrectomy with gastroduodenostomy • Billroth 2 (B2) procedure ○ Distal gastrectomy with gastrojejunostomy • Surgery for gastric cancer ○ May be some variant of B1 or B2, up to total gastrectomy • Complications include recurrent tumor and acute or chronic sequelae of surgery • Recurrent or new carcinoma ○ Local, lymph node, peritoneal, hematogenous • Bezoar formation ○ Conforms to shape of stomach, traps air within • Anastomotic leak ○ CT may detect indirect signs of leaks missed on upper gastrointestinal (GI) series (up to 50% of cases) • Duodenal stump leakage

(Left) Graphic depicts an isoperistaltic Billroth 2 gastrojejunostomy. The afferent limb , composed of the duodenum and a variable length of jejunum, carries pancreaticobiliary secretions toward the stomach, while the efferent limb carries fluid and food downstream. (Right) Graphic depicts an antiperistaltic Billroth 2 procedure, in which the afferent loop enters the anastomosis from a left-toright direction. This procedure is intended to reduce the prevalence of bile gastritis.

(Left) Film from a small bowel follow-through (SBFT) shows evidence of a prior Billroth 2 procedure and complete obstruction of antegrade flow of barium in the mid jejunum . At surgery, a phytobezoar was removed, which corresponded to the shape and size of the gastric remnant. (Right) Film from an upper GI series shows evidence of a prior Billroth 1 procedure, along with persistent filling defects within the stomach that conform to the shape of the stomach, a bezoar.

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○ Loculated collection of fluid in subhepatic space ○ Rarely diagnosed on upper GI • Jejunogastric intussusception ○ Rare complication of B2 procedure • Afferent loop syndrome ○ Obstruction of afferent loop at or near anastomosis dilation of duodenum

DIAGNOSTIC CHECKLIST • Upper GI series is 1st-line test for detecting mechanical complications of gastric surgery • CT is optimal test for general surveillance for postoperative complications • PET/CT is optimal imaging test for surveillance of recurrent gastric carcinoma • Abscessogram may identify leak as source of infection

Partial Gastrectomy: Bilroth Procedures

General Features • Many to most fluoroscopic exams of esophagus, stomach, and duodenum are now performed for patients who have surgically altered anatomy • Some procedures are so common they are discussed separately ○ Postoperative state, esophagus – Includes esophagectomy with gastric pull-through ○ Fundoplication complications ○ Bariatric surgery • Goal for evaluating remaining procedures ○ Define expected postoperative anatomy ○ Describe imaging approaches to evaluation of postoperative patients ○ Describe imaging and clinical findings for various complications

Surgical Procedures • Billroth 1 (B1) procedure ○ Antrectomy with gastroduodenostomy ○ Polya variation: Entire excised end of gastric stump is used for anastomosis ○ Hofmeister: Only a portion (usually greater curvature portion) is used • Billroth 2 (B2) procedure ○ Distal gastrectomy with gastrojejunostomy – Stomach may be anastomosed to Roux limb or loop of jejunum – Anastomosis is side to side – Variable length of duodenum and jejunum forms proximal or afferent loop □ Carries pancreaticobiliary secretions toward stomach – Distal or efferent loop carries food and fluid downstream – Isoperistaltic anastomosis (right to left) □ Afferent limb 1st contacts lesser curve side of anastomosis; efferent limb contacts distal side – Antiperistaltic (left to right) □ Opposite configuration – Duodenal stump is closed by sutures □ Usually filled with gas bubble on postoperative CT □ Located in subhepatic space – Anastomotic loop may be brought to gastric remnant in antecolic or retrocolic position □ Antecolic: Results in longer afferent loop □ Retrocolic: Shorter afferent loop; considered more "physiological" and usually preferred • Surgery for gastric cancer ○ Varies according to site and size of tumor ○ May be some variant of B1 or B2, up to total gastrectomy – Gastrectomy usually results in creation of esophagojejunal anastomosis ○ Usually involves extensive denervation of stomach – Alters gastric and intestinal motility and absorption

Complications • Recurrent or new carcinoma

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○ Patients who have had partial gastrectomy for gastric cancer have high risk of recurrent tumor – May occur in gastric remnant or anastomosis (often causes bowel thickening or obstruction) – Lymph node metastases (celiac, retroperitoneal, mesenteric) – Peritoneal (nodular thickening of peritoneum or omentum; loculated ascites) – Hematogenous (liver, lungs, adrenals, ovaries [Krukenberg tumors]) ○ Patients who have had B2 surgery for benign ulcer disease also are at risk – 3-6x risk of cancer in gastric stump, with 15-20 year latent period – Related to chronic bile gastritis and achlorhydria Gastric stasis ○ postprandial bloating, vomiting, weight loss ○ Not always due to mechanical obstruction – May be due to vagus denervation, gastritis, etc. Dumping syndrome ○ Symptoms: Weakness, dizziness, sweating, nausea, colic, diarrhea ○ Urgent desire to lie down after eating ○ Attributed to vasomotor and cardiovascular etiology ○ Prevalence of 5-50%, depending on type of procedure ○ Usually improves with dietary alterations – Rarely improved by reoperation Bezoar formation ○ prevalence after B1 or B2 ○ Predisposing factors: Achlorhydria, denervation, edentulous patient, anastomotic stricture ○ Distinguish from semisolid food (which will eventually pass through stoma) – Bezoar conforms to shape of stomach, traps air within, floats on fluid in stomach, does not exit with food Anastomotic leak ○ Can occur after any procedure – Highest after surgery for gastric cancer, especially total gastrectomy (with esophagojejunostomy) – Multifactorial, including debilitated condition ○ Early complication – Days to weeks ○ Diagnosed by extraluminal gas, contrast material, fluid – Upper gastrointestinal (GI) series best for some early leaks – CT may be necessary for evaluation of complete extent of fluid collection or abscess – CT may detect indirect signs of leaks missed on upper GI series (up to 50% of cases) – Loculated collections of fluid and gas, extravasated contrast medium Duodenal stump leakage ○ Loculated collection of fluid in subhepatic space on CT – Rarely diagnosed on upper GI ○ Bile and pancreatic juice cause peritoneal inflammation (thick and enhancing) Stomal ulceration ○ May occur after B1 or B2 ○ Usually on small bowel side of anastomosis

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IMAGING

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Partial Gastrectomy: Bilroth Procedures ○ Difficult to depict ulcer on imaging (due to distorted anatomy, thick folds) – Endoscopy is preferred technique • Jejunogastric intussusception ○ Rare complication of B2 procedure ○ Due to prolapse of jejunum through anastomosis into gastric remnant ○ Can cause bowel obstruction ± ischemia – Can be recognized by upper GI or CT as filling defect within stomach, having jejunal fold pattern, peristalsis • Afferent loop syndrome ○ Obstruction of afferent loop at or near anastomosis dilation ○ Loop distends with pancreatic and bilious secretions ○ Symptoms: Pain, nausea, signs of biliary obstruction ○ May be missed or indirectly suggested by upper GI – Afferent loop fails to fill with ingested contrast medium (can be normal) ○ CT shows distended afferent limb (2nd and 3rd portions of duodenum) – May depict tumor in gastric remnant or bowel as obstruction etiology • Chronic remnant gastritis ○ Chronic bathing of gastric mucosa by alkaline bile and pancreatic juice – Routinely causes gastritis – May progress to intestinal metaplasia or cancer – Upper GI and CT show thickened rugal folds ± ulcers or tumor

Imaging Recommendations • Protocol advice ○ Immediate postoperative period – Water-soluble contrast agents for fluoroscopic upper GI (or CT) □ Use nonionic (low osmolar) agent if aspiration is a concern – For evaluation of anastomotic leak: Staple line dehiscence, bowel perforation, abscess – Precede with scout film of abdomen □ Assists in recognizing surgical clips, drains, etc. □ Makes identification of leak more apparent on postprocedure films ○ Later evaluations – Barium is used for upper GI series – Single contrast study answers most clinically relevant questions – Double contrast study better shows superficial ulcers but is more difficult to perform and interpret

CLINICAL ISSUES Presentation • Other signs/symptoms ○ Other complications – Infection □ Most common source of morbidity and mortality following gastric surgery □ Pulmonary, urinary □ Operative wound; often indicative of anastomotic leak 272

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□ Undrained fluid may become infected (CT: Enhancing wall ± gas) □ Pneumoperitoneum may be normal postoperative finding or indicative of leak Esophageal dysmotility □ Effects of vagotomy or surgical injury Esophagitis □ From acid or alkaline reflux Gastric-emptying problems □ Gastroparesis or outlet obstruction □ Bezoar □ Generalized ileus □ Fistulas (gastrocolic, gastrojejunal) Malabsorption □ Inadequate mixing of pancreatic juice, bile, enteric contents □ Inadvertent gastroileostomy Hemorrhage □ Sentinel clot (heterogeneous high attenuation blood [45-65 HU] near source of bleeding) Pancreatitis □ Due to injury of pancreas at surgery or invasion of pancreas by gastric tumor requiring partial pancreatectomy

DIAGNOSTIC CHECKLIST Consider • Upper GI series is 1st-line test for detecting mechanical complications of gastric surgery ○ Leak, obstruction, etc. ○ Misses leaks in up to 50% of cases (in some series) • CT is optimal test for general surveillance of postoperative complications ○ Infection, mechanical problems, tumor, etc. • PET/CT is optimal imaging test for surveillance of recurrent gastric carcinoma • Abscessogram ○ Injection of contrast medium through surgically or radiologically placed drains ○ May identify opacification of bowel or stomach – Indicates leak as source of infected fluid collection

Image Interpretation Pearls • Try to identify anatomy on CT and use medical records (opreports, etc.) ○ Important to identify, for instance, what constitutes the afferent limb – Always in continuity with 3rd portion of duodenum – Crosses between aorta and superior mesenteric vessels

SELECTED REFERENCES 1.

Han Y et al: Cure and prevention strategy for postoperative gastrointestinal fistula after esophageal and gastric cardiac cancer surgery. Hepatogastroenterology. 61(133):1253-6, 2014

Partial Gastrectomy: Bilroth Procedures Stomach

(Left) 30-minute delayed film from a SBFT in an elderly man, who had a Billroth 2 procedure for benign ulcer disease 15 years prior, shows preferential filling of the afferent limb and delayed and decreased filling of the efferent limb. (Right) Axial CECT in the same patient shows luminal distention and wall thickening of the gastric remnant near the gastroenteric anastomosis , due to gastric carcinoma. Liver metastases are evident .

(Left) Axial CECT in the same patient shows extensive mesenteric lymphadenopathy from lymphatic metastases. (Right) Axial CECT in the same patient shows a large mesenteric tumor encasing the efferent limb . The contrast-filled lumen of the afferent limb is seen . Gastric cancer occurs with increased frequency following this type of ulcer surgery, usually 15 or more years later.

(Left) Jejunogastric intussusception as a complication of partial gastrectomy with Billroth 2 anastomosis. CT demonstrates a loop of thick-walled and ischemic jejunum within the distended gastric remnant . (Right) Coronal reformation CECT in the same patient shows the retrograde intussusception with invagination of bowel, mesenteric fat, and vessels into the gastric remnant (intussuscipiens). This is a rare complication but may result in bowel obstruction and ischemia.

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Fundoplication Complications KEY FACTS

TERMINOLOGY • Nissen fundoplication (FDP): Complete (360°) FDP • Toupet FDP: Partial (270°) FDP, posterior side • Belsey Mark IV repair: 240° FDP wrap around left lateral aspect • Nissen-Collis procedure creates "neoesophagus" ○ GE junction (at B ring) will be above diaphragm; intact wrap around proximal stomach (neoesophagus) will be below diaphragm

IMAGING • Preoperative: Identify "short esophagus," hiatal hernia, and dysmotility • Wrap complications ○ Tight FDP wrap (fixed narrowing and delayed emptying of esophagus) ○ Complete disruption of FDP sutures (recurrent hernia and reflux), partial disruption of FDP sutures (1 or more loose-looking outpouchings of wrap)

(Left) Graphic shows a Nissen fundoplication (FDP) with the gastric fundus wrapped completely (360°) around the gastroesophageal junction. (Right) Upright spot film from an esophagram performed soon after a Nissen FDP shows an intact wrap in its expected subdiaphragmatic location as a filling defect within the air-filled fundus. The distal 3 cm of the esophageal lumen is compressed as it passes through the wrap.

(Left) A supine film from the same study shows the intact wrap as a filling defect with the barium pool in the fundus. (Right) Axial NECT shows an intact FDP as a soft tissue density mass within the gastric fundus. The metallic staple line is evident within the wrap. The mass effect of the wrap tends to decrease with time following surgery.

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○ Intact wrap may slide downward over stomach; "hourglass" configuration of stomach ○ Intrathoracic migration of wrap upward through hiatus • Fluid collections in abdomen or mediastinum ○ Herniated abdominal fluid, lymph, hematoma, infection ± leak, abscess • Videofluoroscopic contrast-enhanced esophagram soon after surgery is mandatory ○ Provides structural information, anatomical abnormalities ○ Wrap complications, leaks, persistence of reflux • CT for severe abdominal or chest pain, suspected visceral injury, or abscess

DIAGNOSTIC CHECKLIST • Postoperative fluoroscopic evaluation should be used liberally or even routinely • CT for suspected leak or bleeding

Fundoplication Complications

Abbreviations • Fundoplication (FDP)

Definitions • Complications of antireflux surgery for management of gastroesophageal reflux disease (GERD) • Nissen FDP: Complete (360°) FDP ○ Approach: Laparoscopic or open FDP ○ Gastric fundus wrapped 360° around intraabdominal esophagus to create antireflux valve ○ Concomitant hiatial hernia is reduced; diaphragmatic esophageal hiatus sutured • Toupet FDP: Partial (270°) FDP ○ Posterior hemivalve created • Belsey Mark IV repair: Open surgical; 240° FDP wrap around left lateral aspect of distal esophagus ○ Fundus sutured to intraabdominal esophagus; acute esophagogastric junction angle (angle of His) ○ Can also be performed via minimally invasive techniques

IMAGING Radiographic Findings • Fluoroscopy • Preoperative evaluation is critical to identify ○ Presence, type and size of hiatal hernia (HH) ○ Irreducible HH or "short esophagus" – Stomach is pulled taut into chest; does not return to abdomen on upright positioning – May require Collis gastroplasty (effectively lengthening esophagus by creating a gastric tube) – Wrap goes around "neoesophagus" in abdomen = Nissen-Collis FDP ○ Also evaluate for reflux and esophageal motility – FDP is relatively contraindicated in patients with severe dysmotility • Normal postoperative appearance ○ Nissen FDP wrap: Well-defined mass in gastric fundus; smooth contour and surface – Distal esophagus tapers smoothly through center of symmetric compression by wrap – Tapered segment 2-3 cm long – Pseudotumoral defect within gastric fundus = wrap □ Defect more pronounced for complete wrap of Nissen than partial wrap of Toupet, Belsey □ Best detected on upright film (wrap outlined by air in fundus), or supine (wrap as filling defect in barium pool) ○ Toupet (partial, posterior) FDP – Barium may fill portions of wrap □ Don't mistake for leak or dehiscence □ Distal esophagus should still be "squeezed" ○ Nissen-Collis procedure – Gastroesophageal (GE) junction (at B ring) will be above diaphragm – Intact wrap around proximal stomach (neoesophagus) will be below diaphragm □ Look for gastric folds within neoesophagus ○ Belsey Mark IV repair

– Wrap produces smaller defect than Nissen FDP – 2 distinct angles form as esophagus passes FDP • "Wrap" complications ○ Tight FDP wrap – Fixed narrowing of distal esophagus with delayed emptying – May also see gas distention of stomach (gas bloat syndrome) ○ Complete disruption (dehiscence) of FDP sutures – Findings may resemble those of normal patient who has had no surgery – Recurrent hiatal hernia and gastroesophageal reflux – Gastric outpouching above diaphragm – Expected mass of FDP wrap and narrowing of distal esophagus are not seen ○ Partial disruption of FDP sutures – Partially intact wrap; does not squeeze distal esophagus – 1 or more small outpouchings from fundus ○ Slipped Nissen – Intact wrap may slide downward over stomach – Hourglass configuration of stomach caused by wrap pinching stomach ○ Intrathoracic migration of wrap – Intact FDP wrap herniates partially or entirely through esophageal hiatus of diaphragm • "Non-wrap" complications ○ Leaks, fistula – Detected by extravasation of oral contrast medium – Uncommon since neither esophageal nor gastric wall is usually cut

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TERMINOLOGY

CT Findings • "Wrap": Soft tissue density mass surrounding intraabdominal esophagus ○ Extending caudally about 3 cm ○ Normal postsurgical esophagus is collapsed without gas or fluid distention • Wrap dehiscence: Circumferential thickening surrounding distal esophagus (due to wrap) is lacking ○ May see recurrent HH; reflux of contrast material into esophagus • Herniation of intact FDP through diaphragmatic hiatus; seen as mediastinal mass on coronal reformatted images • Retraction injury to adjacent organs ○ May result in liver or splenic laceration ○ Right ventricular laceration; cardiac tamponade – Trauma by liver retractor during laparoscopic FDP ○ Bleeding and hematoma in gastric wall or in peritoneal spaces adjacent to stomach and duodenum • Fluid collections in abdomen or mediastinum ○ Ascites, disrupted lymphatic drainage, hematoma, infection ± leak, abscess ○ Drainage under CT guidance; may obviate reoperation • Hollow visceral perforation ○ Extraluminal contrast, free air in chest or abdomen • Superior mesenteric vein and portal vein thrombosis ○ Rare; ~ 2 weeks after laparoscopic FDP

Imaging Recommendations • Best imaging tool 275

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Fundoplication Complications ○ Videofluoroscopic contrast-enhanced esophagram – Structural or morphological abnormalities – "Wrap" complications, leaks, persistence of reflux ○ CT for severe abdominal or chest pain, suspected visceral injury, or abscess • Protocol advice ○ Perform initial postoperative esophagram with watersoluble contrast medium ○ Film initially in standing oblique positions ○ Include supine films to exclude leak or reflux

PATHOLOGY General Features • Etiology ○ Surgeon inexperience, operative technique • Indications for antireflux surgery ○ Medical treatment ineffective ○ Side effects of long-term medications ○ Complications of GERD; esophagitis, stricture, recurrent aspiration pneumonia, asthma, etc. • Surgery also entails repair of large paraesophageal hernias associated with GERD

CLINICAL ISSUES Presentation • Tight wrap: Dysphagia; transient in early postoperative period ○ Gas bloat syndrome; upper abdominal fullness, inability to belch, early satiety, flatulence • Nausea, retching, epigastric pain, diarrhea • Intrathoracic wrap migrations ○ 64% of radiologically visualized intrathoracic migrations have no clinical manifestations • Intrathoracic gastric herniation after FDP is uncommon, but potentially life threatening ○ May lead to gastric volvulus, intrathoracic incarceration of stomach, acute gastric perforation • Too loose or dehisced FDP: Recurrent reflux symptoms • Leaks: Pain, fever, leukocytosis • Visceral injury: Pain, falling hematocrit

Demographics • Epidemiology ○ Incidence of complications is increasing as many laparoscopic FDPs are performed indiscriminately – Intrathoracic migration of wrap: 30% after laparoscopic Nissen FDP, 9% after open procedure □ Varies by experience and skill of surgeon – Incidence of paraesophageal hernia is higher after laparoscopic than open FDP

○ Recurrence of GERD after Nissen: 8% have symptomatic reflux, 4% by objective testing – After Toupet: Symptomatic GERD (20%), objective (51%) – Higher prevalence of patient dissatisfaction, resumption of proton pump inhibitor use • Laparoscopic FDP: 3.5-5% rate of early postoperative complications ○ Surgical failure rate requiring reoperation: 2-17% • Outcome: Good as long as FDP remains intact ○ Overall mortality rate: 0.3% • Antireflux surgery undertaken primarily to improve quality of life by relieving symptoms of GERD ○ Small possibility of reflux symptoms becoming worse after FDP operation (1-2% of patients) ○ Creation of new symptoms due to side effects of surgery; may adversely impact quality of life

Treatment • Minimize complications: Increased surgeon experience and training ○ Appropriate operative and imaging techniques ○ Low threshold for early laparoscopic reexploration, early radiological contrast studies ○ 5-10% of time; may need to change to open procedure while laparoscopic surgery in process • Dilation of esophagus; reoperation to loosen wrap around esophagus if dysphagia or gas bloat persists • Repeat laparoscopic Nissen can be performed safely after initial laparoscopic approach; low failure rate • Prevent recurrent hernia after laparoscopic Nissen FDP ○ Appropriate closure of crura and anchoring suture between stomach and diaphragm are helpful ○ Reinforcement of hiatal crura using prosthetic mesh

DIAGNOSTIC CHECKLIST Consider • Preoperative evaluation by fluoroscopy is critical ○ Identify presence, type, and size of HH, especially an irreducible HH (short esophagus) ○ Identify stricture, Barrett esophagus, esophageal carcinoma ○ Identify and grade degree of esophageal dysmotility • Postoperative fluoroscopic evaluation should be used liberally or even routinely ○ CT for suspected leak or bleeding

SELECTED REFERENCES 1. 2.

Natural History & Prognosis • Advantages of laparoscopic FDP: Safe, effective, reduced length of hospital stay and recovery time ○ Effective even at long-term follow-up; as effective as open procedures with lower morbidity rate • Laparoscopic Toupet vs. Nissen FDP ○ Similar short-term results ○ In longer follow-up, no difference in incidence of postFDP symptoms related to gas-bloat syndrome 276

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Schijven MP et al: Laparoscopic surgery for gastro-esophageal acid reflux disease. Best Pract Res Clin Gastroenterol. 28(1):97-109, 2014 Jobe BA et al: Preoperative diagnostic workup before antireflux surgery: an evidence and experience-based consensus of the Esophageal Diagnostic Advisory Panel. J Am Coll Surg. 217(4):586-97, 2013 LeBedis CA et al: The diagnostic and therapeutic role of imaging in postoperative complications of esophageal surgery. Semin Ultrasound CT MR. 34(4):288-98, 2013

Fundoplication Complications Stomach

(Left) A semirecumbent film from an esophagram shows an intact but "tight" FDP with persistent dilation of the esophagus and delayed emptying. The undersurface of the wrap is seen as a filling defect within the gastric fundus. (Right) This upright film shows marked dilation of the esophagus and delayed emptying as signs of a "too tight" Nissen FDP.

(Left) Spot film from an esophagram shows intrathoracic migration of an intact Toupet FDP. Contrast fills the portions of the fundus that constitute the wrap, but the compression of the distal esophagus is maintained. (Right) Spot film from an esophagram shows a slipped and partially dehisced Nissen-Collis FDP. Barium fills the fundic wrap , which has slipped through the hiatus . Suture disruption is implied by the loose compression of the neoesophagus. The B ring marks the esophagogastric junction.

(Left) Slip of an intact Toupet FDP is seen as intact compression of the distal esophagus , but well above the diaphragm . (Right) A supine film from the same study shows barium filling part of the Toupet wrap . This should not be mistaken for a perforation. Note the intact gastric folds within the wrap. The Toupet wrap is often used in older patients with poor esophageal motility, as evident in this patient by slow emptying of the esophagus and tertiary contractions.

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Fundoplication Complications

(Left) Spot film from an esophagram shows extravasation of contrast medium and gas into the mediastinum, indicating perforation of the esophagus or the wrap. (Right) An axial CT section in the same case shows large collections of gas and fluid in the mediastinum due to perforation of the Nissen FDP.

(Left) This elderly patient recently had repair of a large paraesophageal hernia and FDP. A spot film from an esophagram demonstrates extravasation of contrast medium into the mediastinum, from the distal esophagus. Very little contrast reaches the stomach. (Right) NECT in the same case shows a large mediastinal fluid collection of near-water attenuation , and residual herniation of the stomach . The dense collection of extraluminal contrast indicates a leak from near the operative site.

(Left) This elderly woman had chest pain and fever following FDP. A spot film from an esophagram shows extravasation of contrast into the mediastinum and left pleural space , indicating a leak from the distal esophagus. Very little contrast enters the stomach. (Right) Axial NECT shows a left chest tube that drained a loculated left hydropneumothorax (not shown here), left lower lobe pneumonia, and extravasated gas and contrast within the mediastinum .

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Fundoplication Complications Stomach

(Left) This elderly man had a falling hematocrit following surgical repair of a large paraesophageal hernia. Axial NECT shows a large mediastinal hematoma in the space formerly occupied by the herniated stomach. Hemothorax is also evident . (Right) In the same patient, metallic anchors are present from the mesh repair of the large hernia, and more mediastinal hematoma is seen . This hematoma should not be mistaken for leak of contrast medium.

(Left) This 67-year-old man had FDP performed by an inexperienced surgeon. A splenic laceration occurred during surgery leading to splenectomy. A postoperative CT shows gas and fluid in the splenectomy bed . (Right) A more caudal CT section shows a loculated collection of gas and fluid , subsequently confirmed to be due to a leak from the operative site. A small liver laceration is also seen.

(Left) A more caudal CT section shows more of the extravasated gas and fluid from the FDP site. (Right) A sagittal reformatted image from the CT scan shows the left subphrenic collection of extravasated gas and fluid near the site of the FDP.

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Imaging of Bariatric Surgery KEY FACTS

IMAGING • Laparoscopic adjustable gastric banding (LAGB) procedure (a.k.a. "lap band") ○ Complications: Less common and less varied ○ May be too tight or too loose ○ May erode into stomach or esophagus • Sleeve gastrectomy (gastric sleeve) ○ 75% of stomach is removed by dividing stomach along its long axis – Complications: Less or comparable to LAGB, less than Roux-en-Y gastric bypass (RYGB) – Leak: Early complication seen in < 1% – Stricture in mid stomach (transient or persistent) • RYGB procedure ○ Gastrointestinal complications occur in ~ 10% ○ Anastomotic stricture – Dilatation of gastric pouch, spherical shape, air-fluidcontrast material levels, delayed emptying

(Left) Graphic depicts the gastric banding procedure in which a silicone band is looped around the proximal stomach. A tube connects the inflatable liner of the band to a subcutaneously placed port that can be accessed and inflated or deflated with injections of fluid. (Right) Spot film from an esophagram shows the gastric band in its expected position with a "Phi" angle of ~ 45° (normal). The dilated, slowly emptying esophagus indicates that the band is too tight and fluid will be removed from the access port .

(Left) Radiograph shows an abnormal position of the gastric band , which has slipped inferiorly and rotated clockwise. The connecting tubing has also migrated into a more rightward position than expected. (Right) An upright film from an esophagram in the same patient shows dilation of a larger than expected portion of the proximal stomach with air-fluid-contrast levels, indicating stasis. Slip and rotation of the band often result in obstruction and require revision.

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○ Anastomotic leaks – Most commonly at gastrojejunal anastomosis – CT may demonstrate major and minor leaks; fluid collections not evident on upper GI series ○ Marginal ulcers; rate of 0.5-1.4% after RYGB – Usually result of ischemia ○ Small bowel obstruction (SBO) – Most common etiology: Internal hernias (IH) and adhesions – IH: CT appearance depends on location – Clustering of SB loops; congestion, crowding, twisting of mesenteric vessels ○ Obstruction of excluded stomach and biliopancreatic limb – Cannot be diagnosed with upper GI series; CT is key – May progress to perforation (often fatal) • CT and upper GI radiography have complementary roles

Imaging of Bariatric Surgery

Definitions • Imaging techniques and findings used to evaluate possible complications of surgical procedures meant to induce weight loss

IMAGING General Features • Morphology ○ Laparoscopic adjustable gastric banding (LAGB) procedure – Silicone band with inflatable cuff is looped around fundus, 2-3 cm below gastroesophageal (GE) junction – Opening (stoma) is adjustable by accessing subcutaneous port connected to inflatable cuff □ Fluid is injected into or removed from port to inflate or deflate cuff – Complications: Less common and less varied than in laparoscopic Roux-en-Y gastric bypass (RYGB) procedure – May be too tight ( nausea, dehydration, excessive weight loss) or too loose ( insufficient restriction of food intake) – Twisting or displacement of band (4-13% of patients) □ Should lie at a "phi" angle (between vertical line and horizontal axis of band) between 30 and 60 degrees □ May slip down and twist, partially obstructing gastric lumen through band □ Signs of slip: Phi angle > 60 degrees □ Distended stomach above band with slow emptying (air-fluid levels) □ "O" sign: On frontal image, gastric band is en face seen as an "O" rather than seen in profile – May erode into stomach (1-14% of patients) □ Partial erosion: May have nonspecific symptoms □ Oral contrast coats intragastric band; may not extravasate beyond stomach □ Complete erosion: May see intraperitoneal spill of contrast medium (CT or upper GI) – Leak from stomach may occur even without erosion of band into stomach (early complication) ○ Sleeve gastrectomy (gastric sleeve) – 75% of stomach is removed by dividing stomach along its long axis □ Removes the greater curvature portion of fundus, body, and proximal antrum □ Remaining stomach only holds volume of ~ 100 mL – Complications: Less or comparable to LAGB, less than RYGB □ Leak: Early complication seen in < 1% □ Usually along proximal end of staple line □ Extends laterally from greater curvature □ Stricture: Early or late complication □ Focal narrowing in mid gastric pouch, at end of staple line □ May be transient or require stent or revision □ Gastroesophageal reflux (in 20% of patients)

○ Laparoscopic Roux-en-Y gastric bypass procedure (RYGB) – Surgeon divides stomach into small (~ 30 mL) gastric pouch (parts of cardia and fundus) and much larger excluded stomach – Excluded stomach empties into duodenum as usual, now referred to as biliopancreatic limb – Pouch is anastomosed to roux limb of jejunum (alimentary limb) that is 75-150 cm long □ Roux limb is usually placed in antegastric and antecolic location – Roux (alimentary) and biliopancreatic limbs are joined side-to-side (J-J anastomosis) – Normal post-op upper GI study □ Usually performed within 48 hours of surgery to exclude leak or obstruction □ Esophagus and pouch should empty rapidly into roux limb □ Blind end of roux limb should not be mistaken for leak or ulcer □ Enteric contrast usually opacifies intestine to and beyond jejunojejunal (J-J) anastomosis □ Helps to exclude stricture at or near J-J anastomosis – Complications: More varied and common than with other bariatric procedures □ Spasm or stricture at pouch-enteric anastomosis □ Early (spasm) or late (stricture) complication □ Recognized by dilated pouch with air-fluid level and slow emptying □ Fairly common but may resolve or respond to balloon dilation – Leak: Usually at pouch-enteric anastomosis (up to 5% of cases) □ Early (within 10 days) complication □ Detected with upper GI or CT (complementary) by extravasation of water-soluble contrast medium □ May be contained; look for opacification of surgical drain lumen □ May extend into larger spaces, usually left subphrenic and around spleen – Marginal ulcer □ Reported in 3-10% (more common after revision of prior gastric surgery) □ May result from reflux of acid up roux limb or ischemic injury □ Usually appears as fixed collection of barium with adjacent fold thickening □ Near pouch-enteric anastomosis – Gastro-gastric fistula □ Opening of staple line meant to divide gastric pouch from excluded stomach □ Evident by orally administered contrast material entering excluded stomach □ May account for failure to lose expected weight, but this is relatively rare complication – Small bowel obstruction (affects 5-10% of RYGB patients) □ Any site of obstruction may be due to adhesions or internal hernia □ Think "ABC"

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TERMINOLOGY

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Imaging of Bariatric Surgery □ "A" = Alimentary (roux) limb is dilated □ Often down to near J-J anastomosis □ "B" = biliopancreatic limb (excluded stomach, duodenum, and proximal jejunum) □ This is a closed loop obstruction and will not be detected by upper GI series (CT is essential) □ Risk of perforation of stomach or duodenum; usually constitutes surgical emergency □ "C" = Common channel of bowel beyond J-J anastomosis – Internal hernias are as common as adhesive obstructions in some reports □ CT is more sensitive and specific than fluoroscopic barium studies for diagnosis of internal hernia □ CT signs of internal hernia □ Cluster of small bowel loops in abnormal location □ Through defect in small bowel or transverse colon mesentery □ Or between mesentery of roux limb and transverse colon (Peterson hernia) □ Twisted, displaced, ± dilated mesenteric vessels □ Displacement of J-J anastomotic staple line (from expected left mid abdomen to right side of abdomen usually)

Imaging Recommendations • Best imaging tool ○ CT and upper GI radiography; complementary roles – Some cases of leaks and obstructions will be more evident on one or the other study – Fluoroscopy is better at detecting marginal ulcers and pouch-enteric anastomotic strictures – CT is better for diagnosis of internal hernia, obstruction of biliopancreatic limb, and complications such as abscess following anastomotic leak • Protocol advice ○ Upper GI series with water-soluble contrast material; performed routinely within 24 hours after surgery – If leak is suspected but not shown on study with water-soluble contrast medium, barium may be administered to detect subtle leak ○ CT used if small bowel obstruction or intraabdominal abscess suspected – In all patients with unexplained fever, pain, abdominal distension following bariatric surgery

CLINICAL ISSUES Presentation • Leaks: Incidence of 1-6% after laparoscopic RYGB or LAGB ○ Most dreaded complication of bariatric surgery – May result in sepsis or death ○ Leaks usually occur within first 10 days of surgery ○ May present with only tachycardia, abdominal discomfort, with no signs of peritonitis or fever ○ High index of suspicion; especially if respiratory distress and tachycardia > 120 beats per minute • Small bowel obstruction ○ Reported in 4-5% of patients after RYGB ○ Laparoscopic approach associated with less trauma; fewer adhesions 282

– prevalence of internal hernia (IH) (3%), however ○ Early obstructions within 3 days to 3 months of surgery; more commonly due to adhesions – Internal hernia (IH) develops later (in 90% > 1 month after surgery) ○ Clinical symptoms of IH: Nonspecific nausea, pain – IH: Prone to volvulus and strangulation of small bowel ○ May result in closed loop obstruction; can be lethal • Stenosis at gastrojejunostomy; due to relative ischemia ○ Incidence: Up to 27% after RYGB ○ Dysphagia, vomiting, dehydration, excessive weight loss; diagnosis usually made with endoscopy ○ Late complication; months after surgery ○ Usually treatable with endoscopic balloon dilation

Demographics • Epidemiology ○ During last 3 decades, incidence of overweight American adults nearly tripled to 35% (> 12 million) ○ RYGB, combination procedure; most common bariatric procedure in North America ○ LAGB and sleeve are gaining in popularity

Natural History & Prognosis • Advantages of bariatric surgery: Significant, sustained weight loss ○ Control or reversal of some obesity-related health problems – e.g., diabetes, arthritis, sleep apnea • Advantages of RYGB: Greater weight loss than other procedures ○ Good long-term weight loss and patient tolerance ○ Acceptable short- and long-term complication rates • Advantages of laparoscopic approach to RYGB: postoperative pain and complications; shorter hospital stay; faster recovery ○ Less invasive; especially benefits high-risk morbidly obese patients with multiple comorbidities • Mortality: < 1% after laparoscopic RYGB, gastric sleeve, or LAGB

DIAGNOSTIC CHECKLIST Consider • Nonspecific clinical presentation of some gastrointestinal complications of bariatric surgery ○ CT and UGI series are important and complimentary ○ Radiologist is often 1st to recognize complications

SELECTED REFERENCES 1. 2. 3. 4. 5.

Gaetke-Udager K et al: A guide to imaging in bariatric surgery. Emerg Radiol. 21(3):309-19, 2014 Levine MS et al: Imaging of bariatric surgery: normal anatomy and postoperative complications. Radiology. 270(2):327-41, 2014 Sonavane SK et al: Laparoscopic adjustable gastric banding: what radiologists need to know. Radiographics. 32(4):1161-78, 2012 Ni Mhuircheartaigh J et al: Imaging features of bariatric surgery and its complications. Semin Ultrasound CT MR. 34(4):311-24, 2013 Kawamoto S et al: Adjustable laparoscopic gastric banding: demonstrated on multidetector computed tomography with multiplanar reformation and 3-dimensional imaging. J Comput Assist Tomogr. 33(2):288-90, 2009

Imaging of Bariatric Surgery Stomach

(Left) Spot film from an esophagram shows a leak of gas and contrast medium following placement of a gastric band around the gastric fundus. (Right) Upright film from esophagram shows an abnormally inferior and clockwise-rotated position of the gastric band . The oral contrast medium flows over (rather than through) the band, which is sharply outlined by gas within the stomach, indicating intragastric erosion. Perigastric scarring prevented free intraperitoneal spill of contrast medium.

(Left) Graphic demonstrates the gastric sleeve (sleeve gastrectomy) procedure, in which 75% of the stomach is removed by dividing it along its long axis. The remaining stomach is banana-shaped and only about 100 mL in volume. (Right) Upright film from an upper GI series in a patient who recently had a gastric sleeve procedure shows the stomach as small and bananashaped, with a focal stricture at the end of the gastric staple line. These strictures are often transient and mild, although this instance required stent dilation.

(Left) This patient had a gastric sleeve procedure 24 hours prior to this upper GI series, which shows extraluminal collections of contrast medium and gas , apparently leaking from the gastric staple line. (Right) CT scan the same day shows collections of gas and contrast medium adjacent to the gastric staple line . Also noted is a subcapsular hematoma , likely caused by a retractor injury during surgery.

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Imaging of Bariatric Surgery

(Left) Graphic shows the typical procedure for a Rouxen-Y gastric bypass procedure, with a small gastric pouch anastomosed to a Roux limb that is 75-150 cm long, and which is anastomosed side-toside with the "biliopancreatic" limb ~ 35-45 cm beyond the ligament of Treitz. (Right) Upper GI series in an RYGB patient shows a minor anastomotic leak, evident only as opacification of the surgical drain that was placed near the gastric pouch . The "pouch-enteric" anastomosis is noted.

(Left) Upper GI series in a patient with a major leak days after RYGB shows a large collection of extraluminal contrast material and gas in the left subphrenic space. There is almost no opacification of the small bowel. This is an unusually large leak from the "pouchenteric" anastomosis, but the location and timing are typical. Surgical drainage and revision were required. (Right) Film from an upper GI series shows an extraluminal collection of contrast medium in a patient following RYGB.

(Left) CT in the same patient shows the pouch-enteric anastomosis and extraluminal collections of oral contrast medium, gas, and fluid. (Right) Another CT section shows more of the extravasated fluid and gas . These often collect around the spleen, as in this case.

284

Imaging of Bariatric Surgery Stomach

(Left) Film from an upper GI series shows a marginal ulcer within the Roux limb just beyond the anastomosis with the gastric pouch. The ulcer was a fixed, featureless collection of barium, unlike the blind end of the Roux limb. (Right) Coronal reformatted CT image following RYGB shows massive dilation of the excluded stomach and biliopancreatic limb . The JJ anastomosis is displaced to the right of midline, and the mesenteric vessels are twisted.

(Left) Axial CT in the same case shows the dilated excluded stomach and biliopancreatic limb . (Right) Another CT section shows the twisted, engorged mesenteric vessels to the dilated loop. These passed through a defect behind the Roux limb (Peterson internal hernia).

(Left) CT shows dilation of small bowel, including both the Roux loop and the biliopancreatic limb. The bowel is dilated past the J-J anastomosis . (Right) Another CT section shows that the point of obstruction at the midline laparoscopic port site , through which the bowel has herniated. Bowel obstruction can result from several circumstances particular to the RYGB technique, including anastomotic strictures, and internal and external hernias, some at laparoscopic port sites, as in this case.

285

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Gastric Polyps KEY FACTS

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Polyps classified based on pathology ○ Hyperplastic, adenomatous, and hamartomatous • Fundic gland polyps: Now most common type ○ Associated with use of proton pump inhibitor (PPI) medication ○ Sometimes considered a variant of hyperplastic polyps • Hyperplastic polyps ○ Virtually no malignant potential ○ Typical: Small, multiple, sessile (< 1 cm) ○ Location: Fundus and body • Adenomatous polyps ○ Less common (< 20% of benign polyps) ○ Increased risk of malignant change ○ Usually solitary, > 1 cm • Hamartomatous polyps ○ Peutz-Jeghers syndrome ○ Can occur as isolated finding (sporadic)

• • • • •

(Left) Graphic shows a pedunculated polyp in the gastric antrum, prone to prolapse through the pylorus with peristalsis. Any type of large polyp may prolapse in this fashion, including large hyperplastic, adenomatous, and even polypoid masses arising from the submucosa, such as lipomas. (Right) Upper GI series shows a polypoid mass in the duodenal bulb that is a prolapsed gastric antral polyp (adenoma).

(Left) Film from an upper GI series in a 57-year-old man shows multiple small, sessile polyps in the gastric body. The appearance and age of the patient are typical for hyperplastic polyps. (Right) Film from an upper GI series of adenomatous polyps in a patient with familial polyposis shows innumerable small polyps throughout the stomach. These are somewhat larger, more numerous, and more irregular in shape than most hyperplastic polyps.

286

Retained food and pills Gastric carcinoma (polypoid type) Gastric metastases and lymphoma Gastric gastrointestinal stromal tumor Ectopic pancreatic tissue

CLINICAL ISSUES • Prevalence of gastric polyps in patients who have upper endoscopy = 6% (2009 study) • Fundic (77%), hyperplastic (17%), malignant (2%), adenomas (< 1%) • Much higher percentage of fundic polyps than in earlier studies ○ Caused by increased use of PPI medications • Syndromic polyps have high association with cancer risk in stomach and other organs ○ e.g., familial polyposis, Peutz-Jeghers syndrome

Gastric Polyps

Definitions • Protruding, space-occupying lesion within stomach ○ Encompass a broad spectrum of conditions that may originate in gastric mucosa or submucosa

IMAGING General Features • Best diagnostic clue ○ Radiolucent filling defect, ring shadow, or contour defect on barium study • Morphology ○ Hyperplastic polyps: Smooth, sessile – Fundic gland polyps: Always sessile, multiple, small ○ Adenomatous polyps: Usually single with lobulated or cauliflower-like surface ○ Hamartomas: Cluster of broad-based polyps • Other general features ○ Polyps classified based on pathology ○ Fundic gland polyps – Variant of hyperplastic polyps (< 1 cm) – Have become most common type of gastric polyp – Associated with use of proton-pump inhibitor medication ○ Hyperplastic polyps – Virtually no malignant potential – Typical: Small, multiple, sessile (< 1 cm) □ Location: Fundus and body – Atypical large: Solitary, pedunculated (2-6 cm), location in body and antrum – Atypical giant: Polyp (6-10 cm) multilobulated mass, location in body and antrum ○ Adenomatous polyps – Less common (< 20% of benign polyps); dysplastic lesions – Increased risk of malignant change via adenomacarcinoma sequence – Usually solitary, occasionally multiple, > 1 cm □ Location: Mostly antrum > body – Histologically: Tubular (75%), tubulovillous (15%), villous (10%) – Gastric adenomatous polyps 30x less common than gastric cancer – Carcinoma in situ and invasive carcinoma: Seen in 50% of adenomatous polyps > 2 cm – 30-40% associated with atrophic gastritis, pernicious anemia, and cancer – Higher risk of coexisting gastric cancer than risk of malignant change in polyp ○ Polyposis syndromes involving stomach – Familial adenomatous polyposis (FAP) syndrome □ > 50% of patients have gastric adenomatous or fundic gland polyps – Hamartomatous polyposis (e.g., Peutz-Jeghers syndrome [PJS]) □ Have increased risk of gastric and other cancers – Cronkhite-Canada, Cowden, etc. □ All rare but associated with gastric polyps

Fluoroscopic Findings • Hyperplastic polyps ○ Typical: Multiple, smooth, sessile, round or ovoid lesions, < 1 cm in size ○ Based on location: Dependent and nondependent wall – Dependent (posterior wall): Radiolucent filling defects – Nondependent (anterior wall): Ring shadows and white rim (barium) ○ Variant: Fundic gland polyps (multiple, up to 50 in fundus, < 1 cm in size) – Small rounded nodules, indistinguishable from hyperplastic polyps ○ Atypical: Large and giant – Large: Solitary, conglomerated, pedunculated, lobulated, 2-6 cm in size – Giant polyps: Multilobulated conglomerate mass with trapping of barium in interstices between lobules; 610 cm in size • Adenomatous polyps ○ Usually solitary or rarely multiple, sessile or pedunculated, more lobulated, > 1 cm in size ○ Pedunculated polyp en face: Hanging from nondependent anterior wall – Mexican hat sign: Characterized by pair of concentric rings – Outer ring: Represents head of polyp – Inner ring: Represents stalk of polyp ○ Lobulated polyp with basal indentation: risk of adenocarcinoma ○ Polyps in antrum tend to prolapse through pylorus – Cause intermittent gastric outlet obstruction – Symptoms of transient nausea and vomiting

Stomach

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Double-contrast upper GI series – En face, profile, and oblique views

DIFFERENTIAL DIAGNOSIS Retained Food and Pills • Filling defects in barium pool simulating polyps

Gastric Carcinoma (Polypoid Type) • Lobulated or fungating mass • Barium study findings ○ Dependent or posterior wall: Filling defect ○ Nondependent or anterior wall – Etched in white by thin layer of barium • Indistinguishable from giant lobulated hyperplastic or adenomatous polyp • Diagnosis: Endoscopic biopsy and histology

Gastric Metastases and Lymphoma • Gastric metastases (e.g., malignant melanoma and squamous cell carcinoma) • Gastric lymphoma (e.g., low-grade mucosa-associated lymphoid tissue [MALT] lymphoma) • Barium study findings ○ Malignant melanoma metastases – Initially: Submucosal masses seen as filling defects may mimic polyps 287

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Gastric Polyps

– Ulcerated lesions: Bull's-eye or "target" pattern ○ Low-grade MALT lymphoma – Confluent varying-sized nodules (filling defects) – May be indistinguishable from gastric FAP syndrome

Gastric GIST • Submucosal lesion, often with intraluminal and large exophytic component • Has smooth mucosal surface unless ulcerated • CT shows more of mass than upper GI series • Diagnosis: Endoscopic biopsy and histology

Ectopic Pancreatic Tissue • Location: Greater curvature of distal antrum • Often contain central umbilication or dimple ○ Represents orifice of primitive ductal system

PATHOLOGY General Features • Etiology ○ Fundic gland polyps – Have become most common type – Associated with increased use of proton-pump inhibitors (PPI) ○ Chronic atrophic and Helicobacter pylori gastritis ○ Hereditary: Autosomal dominant (FAP syndrome and PJS) – Hamartomatous polyposis syndromes • Genetics ○ FAP syndrome: Abnormal or deletion of APC gene located on chromosome 5q ○ Hamartomatous polyposis (PJS) – Spontaneous gene mutation on chromosome 19 • Associated abnormalities ○ Polyposis syndromes

Gross Pathologic & Surgical Features • Hyperplastic polyps: Small, sessile nodules; smooth, domeshaped contour • Fundic gland polyps: Small sessile polyps • Adenomatous polyps: Tubular (thin stalk and tufted head), sessile (broad base) • FAP syndrome: Innumerable small to medium-sized polyps • PJS: Carpet, cluster-like, or scattered polyps

Microscopic Features • Hyperplastic polyps: Elongated, cystically dilated glandular structures • Adenomatous polyps: Tubular, tubulovillous, villous pattern; dysplastic cells • PJS: Muscularis mucosa core extends to lamina propria

○ Pedunculated polyps in antrum: Nausea and vomiting – Due to outlet obstruction • Diagnosis: Endoscopic biopsy and histology

Demographics • Age ○ Hyperplastic polyps: Middle-aged and elderly ○ Fundic gland polyps more common in middle-aged women ○ FAP syndrome and PJS: 10-30 years • Gender ○ M=F • Epidemiology ○ Incidence – Gastric polyps: 1-2% of all GI tract polyps – Prevalence of gastric polyps in patients who have upper endoscopy = 6% (2009 study) □ Fundic (77%), hyperplastic (17%), malignant (2%), adenomas (< 1%) □ Much higher percentage of fundic polyps than in earlier studies – FAP syndrome and PJS: 1 in 10,000 people

Natural History & Prognosis • Complications ○ Risk of cancer in adenomatous polyp, FAP syndrome, and PJS ○ Gastric outlet obstruction • Prognosis ○ Good: After removal of benign and cancer in situ polyp ○ Poor: Invasive carcinoma

Treatment • Small (< 1 cm) and asymptomatic: Periodic surveillance • Large (> 1 cm), sessile or pedunculated, and lobulated and symptomatic: Polypectomy

DIAGNOSTIC CHECKLIST Consider • Differentiate from other gastric discrete filling defects • Check for family history of GI tract polyps • Screen small intestine and colon to rule out associated hereditary polyposis syndromes

SELECTED REFERENCES 1. 2.

3. 4.

CLINICAL ISSUES

5.

Presentation • Most common signs/symptoms ○ Usually asymptomatic ○ Ulcerated polyps: Low-grade upper GI bleeding ○ FAP syndrome: Rectal bleeding and diarrhea ○ PJS: Cramping pain, rectal bleeding, or melena ○ Mostly incidental findings on imaging and endoscopy 288

6.

Declich P et al: Fundic gland polyps and proton pump inhibitors: an obvious link, or an open question? Hum Pathol. 45(5):1122-3, 2014 Islam RS et al: Gastric polyps: a review of clinical, endoscopic, and histopathologic features and management decisions. Gastroenterol Hepatol (N Y). 9(10):640-51, 2013 Jung JT: Gastric polyps and protruding type gastric cancer. Clin Endosc. 46(3):243-7, 2013 Carmack SW et al: The current spectrum of gastric polyps: a 1-year national study of over 120,000 patients. Am J Gastroenterol. 104(6):1524-32, 2009 Genta RM et al: No association between gastric fundic gland polyps and gastrointestinal neoplasia in a study of over 100,000 patients. Clin Gastroenterol Hepatol. 7(8):849-54, 2009 Ba-Ssalamah A et al: Dedicated multidetector CT of the stomach: spectrum of diseases. Radiographics. 23(3):625-44, 2003

Gastric Polyps Stomach

(Left) Film from an upper GI series in an elderly man with dysphagia shows a welldefined polyp at the GE junction. (Right) Another spot film from the upper GI in the same patient shows the polyp prolapsing into the distal esophagus. Endoscopy and resection revealed an adenomatous gastric polyp.

(Left) Film from an upper GI series shows a well-defined polyp in the gastric body. (Right) Endoscopic photograph in the same patient shows an ulcerated mass that was a benign adenoma. A band was placed around the base of the polyp, and it was resected at endoscopy.

(Left) Film from an upper GI series in an elderly man with dyspepsia shows a cluster of polypoid lesions arising from the gastric cardia and body. These have a smooth surface and most appear sessile. (Right) Upper GI series in the same patient shows that some of the polyps appear to have a stalk . Endoscopy revealed multiple polyps with a villous adenoma histology.

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Intramural Benign Gastric Tumors KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Benign mass composed of 1 or more tissue elements of gastric wall • 50% of all benign tumors are intramural ○ Remainder are polyps ○ Gastrointestinal stromal tumor (GIST) is most common ○ Others include lipoma, carcinoid, leiomyoblastoma, lymphangioma, neural tumors

• • • • • • •

IMAGING

CLINICAL ISSUES

• Upper GI series: Intact mucosa, obtuse or right angles with wall • GIST: Often large with central necrosis and ulceration of overlying mucosa on CT • Lipoma: Most common in antrum ○ May prolapse through pylorus into duodenum ○ Well-circumscribed areas of uniform fat density = definitive diagnosis

• Carcinoid tumors may be multiple as a result of excess gastrin secretion (Zollinger-Ellison syndrome or atrophic gastritis)

(Left) Graphic shows a "generic" intramural gastric mass with intact mucosa and slightly obtuse or right angles at the interface with the gastric wall. (Right) Axial CECT shows a discrete fatdensity mass within the gastric wall with intact, stretched mucosa; diagnostic of a lipoma.

(Left) Upper GI series shows a gastric antral mass with a central ulceration , typical of a gastric gastrointestinal stromal tumor (GIST). Note the otherwise intact mucosa over the mass, even with preservation of the areae gastricae. (Right) Endoscopic photograph in the same patient shows the submucosal benign gastric GIST with central ulceration .

290

Gastric carcinoma Gastric metastases and lymphoma Ectopic pancreatic tissue Pancreatic pseudocyst Splenosis Gastric ulcer Hematoma/seroma

DIAGNOSTIC CHECKLIST • Lipomas have pathognomonic CT appearance • GIST has characteristic appearance, but other tumors have overlapping features

Intramural Benign Gastric Tumors

Definitions • Benign mass composed of 1 or more tissue elements of gastric wall

IMAGING General Features • Best diagnostic clue ○ Intramural mass with smooth surface and slightly obtuse borders • Other general features ○ Types of intramural benign gastric tumors – Gastrointestinal stromal tumor (GIST) – Lipoma, leiomyoblastoma, lymphangioma, neural tumors

Radiographic Findings • Upper GI series ○ Discrete mass, solitary (usually) or multiple ○ Smooth surface lesion etched in white (double contrast, profile view) ○ Borders form right angle or slightly obtuse angles with adjacent gastric wall (profile view) ○ Intraluminal surface of tumor has abrupt, well-defined borders (en face view) ○ Usually intact overlying mucosa; normal areae gastricae pattern ○ Bull's-eye or "target" lesions: Central barium-filled crater within mass (ulceration) – ± giant, cavitated lesions (GIST) ○ Pedunculated; may prolapse into duodenum – Lipomas seem especially likely to do so ○ GIST – Most common; may occur anywhere in GI tract – Several mm to 30 cm – Only 1-2% of GISTs are multiple – ± extragastric extensions (86%): Gastrohepatic ligament, gastrosplenic ligament, lesser sac ○ Lipoma, lymphangioma: Tendency to change in size and shape by peristalsis or palpation ○ Schwannoma and neurofibroma: Multiple lesions with associated abnormalities

– May prolapse through pylorus into duodenum ○ Well-circumscribed areas of uniform fat density (-80 to 120 HU) = definitive diagnosis

Stomach

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Upper GI and CT are complementary

DIFFERENTIAL DIAGNOSIS Gastric Carcinoma • Usually appears as polypoid or circumferential mass with irregularity of luminal surface • Large, lobulated, mucosal, hypovascular mass, ± ulceration • Associated with perigastric or hepatoduodenal ligament and celiac lymphadenopathy • Scirrhous lesion that limits peristalsis and distention

Gastric Metastases and Lymphoma • Gastric metastases ○ e.g., breast (most common metastases to stomach), colon, melanoma, lung, pancreas ○ Discrete nodules to linitis plastica (breast metastases) • Gastric lymphoma (e.g., non-Hodgkin B cell) ○ In GI tract, stomach is most common location ○ Associated with bulky adenopathy, or adenopathy extends into lower abdomen and pelvis • Multiple bull's-eye lesions; unlike GIST

Ectopic Pancreatic Tissue • Located on greater curvature of distal antrum • Broad-based smooth, extramucosal, intramural lesion • Central barium collection present in orifice of primitive ductal system; may simulate ulceration • Usually small (5-10 mm)

Pancreatic Pseudocyst • Simulates intramural mass on upper GI, not CT • Encapsulated fluid collection in patient with pancreatitis

Splenosis • Splenules may implant within gastric wall • Enhancement pattern identical to spleen

Gastric Ulcer • Ulcer mound may simulate mass

CT Findings

Hematoma/Seroma

• GIST ○ Often large with central necrosis and ulceration of overlying mucosa ○ Hypo- or hypervascular, well-circumscribed submucosal mass (arterial phase) ○ Peripheral enhancement (92%) – ± homogeneous enhancement (8%) ○ Central area of low attenuation (hemorrhage, necrosis, or cystic formation) – Most GISTs > 2 cm have necrosis ± cavitation ○ Cavitation may communicate with gastric lumen; contain air, air-fluid levels, or oral contrast ○ ± calcification • Lipoma ○ Located commonly in gastric antrum

• May result from placement of gastrostomy tube

PATHOLOGY General Features • Etiology ○ GIST: KIT germline mutations ○ Hemangioma: Possible congenital malformation • Associated abnormalities ○ GIST and neurofibroma: Neurofibromatosis type 1 ○ Hemangioma: Telangiectasias of skin • 50% of all benign tumors in stomach and duodenum are intramural ○ Remainder are mucosal polyps (e.g., hyperplastic, adenomatous, or hamartomatous) 291

Stomach

Intramural Benign Gastric Tumors

• Most are diagnosed incidentally by imaging or autopsy • GIST ○ Most common intramural primary gastric or duodenal mass – Comprises 90% of mesenchymal tumors, 40% of all benign gastric masses ○ 70% of all GISTs occur in stomach, 2-3% of all gastric tumors • Lipoma ○ Comprises 2-3% of benign tumors ○ No malignant degeneration • Carcinoid tumor ○ May be multiple as result of excess gastrin secretion (Zollinger-Ellison syndrome or atrophic gastritis) • Leiomyoblastoma ○ Predominantly in stomach; may affect small bowel, retroperitoneum, uterus ○ Most are benign, 10% malignant (usually > 6 cm) ○ Indistinguishable from GIST by imaging or gross pathology • Hemangioma ○ < 2% of benign tumors in stomach, less in duodenum ○ Multiple hemangiomas in GI tract &/or skin – May be part of syndrome • Lymphangioma: Can occur anywhere, rare in GI tract • Schwannoma and neurofibroma ○ 5-10% of benign tumors in stomach ○ Schwannoma (most common): Neurilemoma, schwannoma, or neuroma ○ Neurofibroma (less common): 10% undergo malignant degeneration

Gross Pathologic & Surgical Features • GIST ○ Propensity for exogastric growth; mass arises from gastric wall and projects into abdominal cavity ○ Mucosal ulceration on luminal surface is common ○ Well-circumscribed mass that compresses adjacent tissue and lacks true capsule ○ ± focal areas of hemorrhage, cystic degeneration, necrosis, and cavitation • Leiomyoblastoma: Smooth muscle tumors • Lipoma: Endogastric (95%) or exogastric (5%) lesions with superficial ulceration due to pressure necrosis • Hemangioma: Numerous tiny vascular structures (capillary) or large blood spaces or sinusoids lined by endothelial tissue (cavernous) • Lymphangioma: Cystic appearance with progressive accumulation of fluid

Microscopic Features • GIST ○ Spindle cell (70-80%): Cigar-shaped cells, elongated nuclei, eosinophilic to basophilic cytoplasm ○ Epithelioid (20-30%): Round polygonal cells, centrally placed nuclei, cytoplasmic vacuolization ○ < 5 cm in largest dimension with 5 mitoses per 50 consecutive high-power fields (HPF): Considered benign ○ > 5 cm with 5 mitoses per 50 HPF: Malignant • Lipoma: Mature fat cells surrounded by capsule 292

• Schwannoma: Bundled spindle-shaped cells with distinctive lymphoid cuff that may contain germinal centers; stain for S100 protein

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic (most common) ○ Upper GI bleeding, nausea, vomiting, abdominal or epigastric pain, weight loss, abdominal distention

Natural History & Prognosis • Complications: Hemorrhage, catastrophic intraperitoneal bleeding • Prognosis: Good, except for patients with malignant degeneration

Treatment • GIST ○ Surgical resection ± chemotherapy (imatinib) ○ Follow-up: Monitor indefinitely for recurrence • Other types of tumors ○ No treatment if small and asymptomatic ○ Surgery if symptomatic; usually curative – Enucleation; local excision, partial gastrectomy, or duodenectomy

DIAGNOSTIC CHECKLIST Consider • Lipomas have pathognomonic CT appearance • GISTs have characteristic appearance, but other tumors have overlapping features

Image Interpretation Pearls • Isolated gastric "target" lesion is usually GIST • Multiple "target" lesions = metastases

SELECTED REFERENCES 1.

Armstrong C et al: Minimally invasive resection of benign gastric tumors in challenging locations: prepyloric region or gastroesophageal junction. Am Surg. 79(10):968-72, 2013 2. Doyle LA et al: PEComa of the gastrointestinal tract: clinicopathologic study of 35 cases with evaluation of prognostic parameters. Am J Surg Pathol. 37(12):1769-82, 2013 3. Kang HC et al: Beyond the GIST: mesenchymal tumors of the stomach. Radiographics. 33(6):1673-90, 2013 4. Kobara H et al: Gastric heterotopic pancreas can be identified by endoscopic direct imaging with submucosal endoscopy. J Gastrointestin Liver Dis. 22(3):345-8, 2013 5. Parmar AK et al: Laparoscopic management of a large duodenal lipoma presented as gastric outlet obstruction. JSLS. 17(3):459-62, 2013 6. Rao C et al: Large gastric lipoma presenting with GI bleeding. Gastrointest Endosc. 77(3):512-3, 2013 7. Levy AD et al: Gastrointestinal stromal tumors: radiologic features with pathologic correlation. Radiographics. 23(2):283-304, 456; quiz 532, 2003 8. Pidhorecky I et al: Gastrointestinal stromal tumors: current diagnosis, biologic behavior, and management. Ann Surg Oncol. 7(9):705-12, 2000 9. Suster S: Gastrointestinal stromal tumors. Semin Diagn Pathol. 13(4):297313, 1996 10. Taylor AJ et al: Gastrointestinal lipomas: a radiologic and pathologic review. AJR Am J Roentgenol. 155(6):1205-10, 1990

Intramural Benign Gastric Tumors Stomach

(Left) Axial CECT in a patient with multiple gastric lipomas demonstrates several fatcontaining masses within the wall of the stomach. Some are pulled by peristalsis into the lumen as polyps on a stalk. (Right) In the same patient, 2 of the lipomas can also be identified. Hepatic lesions are simple cysts. It is uncommon to detect multiple lipomas within the stomach, but these lesions are invariably benign and require no treatment or further evaluation unless they bleed or prolapse into the duodenum with obstructive symptoms.

(Left) Axial CECT in this patient with a benign GIST shows a large exophytic mass arising from the lesser curve of the stomach. It is relatively vascular with central areas of necrosis. (Right) In the same patient, the GIST has prominent and characteristic central necrosis .

(Left) Axial CECT in a middleaged woman with chronic pancreatitis shows calcifications within the head of the pancreas. An unexpected finding was a vascular mass within the posterior wall of the stomach. (Right) Another image in the same patient shows that the vascular intramural mass has intact gastric mucosa "draped" over it. This was resected and proven to be a neurolemmoma of the gastric wall.

293

Stomach

Gastric GIST KEY FACTS

TERMINOLOGY • Submucosal tumor of gastrointestinal (GI) tract derived from interstitial cells of Cajal

IMAGING • Best imaging tools: CECT, PET • Hypo- or hypervascular, well-circumscribed, submucosal mass on arterial phase CECT images; ulceration and necrosis are common ○ Often exophytic ○ Sometimes hemorrhagic • PET is superior to CT in predicting early response to Gleevec (imatinib) ○ Hypermetabolic foci for both primary tumor and metastases

TOP DIFFERENTIAL DIAGNOSES • Gastric lymphoma • Sarcoma invading stomach

(Left) Anatomic depiction of a gastric GIST shows an exophytic submucosal mass with internal necrosis. (Right) Axial CECT shows a soft tissue density left upper quadrant mass . The origin of the mass may not be evident, except for a small projection into the gastric lumen.

(Left) Axial CECT in a 36-yearold woman with nausea and hematemesis shows an encapsulated spherical mass within the stomach wall, which appears to be draped or stretched around it. A gas collection within a surface defect of the mass and the overlying gastric mucosa represents the ulceration (and, presumably, bleeding) site. (Right) Coronal reformat CT (same patient) shows the mass and its relationship to the stomach . Note the focal necrosis and surface ulceration .

294

• Exophytic gastric carcinoma • Submucosal GI lipoma

PATHOLOGY • Distinct, not synonymous with leiomyoma/sarcoma ○ May not be diagnosed by light microscopy alone

CLINICAL ISSUES • Most common mesenchymal tumor of GI tract • Symptoms: Nausea, vomiting, weight loss ○ Mass effect from bulky tumor; GI bleed when ulcerated • Excellent prognosis for completely resected benign lesions • Good response to chemotherapy (imatinib) in patients with metastatic disease and c-KIT mutation • Prognosis often depends on tumor size ○ Poor if > 5 cm

DIAGNOSTIC CHECKLIST • Lymphoma may have similar imaging features but is not hypervascular

Gastric GIST

Abbreviations • Gastrointestinal stromal tumor (GIST)

Definitions • Submucosal tumor of gastrointestinal (GI) tract derived from interstitial cells of Cajal

IMAGING General Features • Best diagnostic clue ○ Well-circumscribed, submucosal mass extending exophytically from GI tract • Location ○ Stomach is most common site (2/3 of cases) ○ Small bowel (especially duodenum) is 2nd most common site ○ May occur anywhere in GI tract ○ Rarely occurs in esophagus – Leiomyoma is more common in esophagus • Size ○ Variable; large mass may be > 5 cm • Morphology ○ Bulky, well circumscribed, and lobulated ○ Often exophytic, may have cystic element

Fluoroscopic Findings • Upper GI ○ Rounded, exophytic, submucosal gastric mass ○ Ulcerations are common in larger masses – Necrotic center of tumor may fill with barium

Nuclear Medicine Findings • PET ○ Superior to CT in predicting early response to imatinib (Gleevec) – Hypermetabolic (FDG-avid) foci indicate viable tumor – For both primary tumor and metastases ○ Sensitivity (86%), specificity (98%)

Imaging Recommendations • Best imaging tool ○ CECT, PET • Protocol advice ○ Distend stomach with 16-32 oz of water prior to CT scanning ○ Use biphasic CECT technique to visualize entire liver – 150 mL IV contrast injected at 4-5 mL/sec – Arterial phase acquisition at 40 seconds, venous phase at 70 seconds ○ Multiplanar reformation – Aids in appreciation of size and origin of mass

DIFFERENTIAL DIAGNOSIS Gastric Lymphoma • • • • • •

Nodular fold thickening on barium studies Exophytic mass without bowel obstruction Associated mesenteric and retroperitoneal adenopathy Bulky, often circumferential, submucosal mass May ulcerate May be indistinguishable from GIST, but lymphoma is rarely hypervascular, unlike GIST

CT Findings

Sarcoma Invading Stomach

• NECT ○ Calcifications in 25% of cases • CECT ○ Hypo- or hypervascular, well-circumscribed, submucosal mass on arterial phase images; ulceration and necrosis are common – Sensitivity = 93%, specificity = 100% ○ Tumors with large intraluminal component may mimic primary gastric carcinoma

• • • • • •

MR Findings • T1WI ○ Isointense (to muscle) mass • T2WI ○ Hypo- to isointense submucosal mass ○ Hyperintense areas of necrosis • T2* GRE ○ Hyper- or hypointense with IV gadolinium • T1WI C+ ○ Variable vascularity; may be hyper- or hypovascular ○ Enhancement of solid areas ○ Nonenhancing necrotic or hemorrhagic areas

Ultrasonographic Findings • Grayscale ultrasound ○ Hypoechoic mass • Color Doppler

Stomach

○ Variable vascularity on color Doppler

TERMINOLOGY

Bulky mass Heterogeneous on CECT Liposarcomas contain fat Secondary invasion of bowel may mimic GIST Primary location in mesentery aids in differentiation Bowel obstruction is common, unlike with GIST

Exophytic Gastric Carcinoma • Hypodense mass less vascular than GIST • May be bulky and exophytic on CT or MR • Focal thickening of adjacent gastric wall and gastric outlet obstruction help differentiate from GIST • Often causes obstruction when circumferential ○ GIST is rarely circumferential

Other Gastric Intramural Neoplasms • e.g., leiomyoblastoma, lymphangioma, neural tumors • Fat attenuation is diagnostic of lipoma • Others may not be distinguished from GIST by imaging alone

PATHOLOGY General Features • Etiology ○ Unknown • Genetics 295

Stomach

Gastric GIST ○ 95% of GISTs express growth factor receptor with tyrosine kinase activity (c-KIT [CD117]) ○ Embryology – Mesenchymal origin, unrelated to leiomyomas or leiomyosarcomas – Derived from stem cells or interstitial cells of Cajal □ Interstitial cells of Cajal help regulate peristaltic activity (pacemaker function) • Associated abnormalities ○ Carney triad – Malignant epithelial gastric GIST – Pulmonary chondroma – Extraadrenal paraganglioma ○ von Recklinghausen disease – Neurofibromatosis type 1

Staging, Grading, & Classification

• Good response to chemotherapy (imatinib [Gleevec]) in patients with metastases and c-KIT mutation • 5-year survival: 50-80% • Prognosis often depends on tumor size ○ Relatively poor if tumor is > 5 cm

Treatment • Surgery with en bloc resection • Tyrosine kinase inhibitor chemotherapy (imatinib) for metastatic disease ○ Imatinib may be useful adjunct even for localized disease

DIAGNOSTIC CHECKLIST Consider • Lymphoma may have similar imaging features but is not hypervascular

• 4 tumor subtypes ○ Benign spindle cell GIST ○ Malignant spindle cell GIST ○ Benign epithelial GIST ○ Malignant epithelial GIST

Image Interpretation Pearls

Gross Pathologic & Surgical Features

1.

• • • •

Bulky submucosal mass Benign lesions are typically small (< 3 cm) Central ulceration common Malignant features include invasion, size > 5 cm, and evidence of metastases

• Exophytic hypervascular GI mass arising from submucosa with central ulceration

SELECTED REFERENCES

2. 3.

4.

Microscopic Features • Distinct, not synonymous with leiomyoma/sarcoma ○ May not be diagnosed by light microscopy alone • Benign or malignant mesenchymal spindle cell or epithelioid neoplasm without muscle differentiation • Malignant features ○ High mitotic rate (> 10 mitoses per 50 high-power fields) ○ High nuclear grade ○ High cellularity

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Nausea, vomiting, weight loss ○ Mass effect from bulky tumor ○ GI bleed when surface of stomach and GIST are ulcerated • Clinical profile ○ No specific lab abnormality

Demographics • Age ○ > 45 years • Gender ○ No predilection • Epidemiology ○ Most common mesenchymal tumor of GI tract

Natural History & Prognosis • Metastasizes to liver, lungs, peritoneal cavity • Excellent prognosis for completely resected benign lesions 296

5.

6.

7.

8.

9. 10. 11.

12. 13.

14. 15. 16. 17.

Corless CL et al: Pathologic and molecular features correlate with long-term outcome after adjuvant therapy of resected primary GI stromal tumor: the ACOSOG Z9001 trial. J Clin Oncol. 32(15):1563-70, 2014 Tap WD et al: That's the "GIST" of it: use of adjuvant imatinib after resection of a primary GI stromal tumor. J Clin Oncol. 32(15):1543-6, 2014 De Vogelaere K et al: Gastrointestinal stromal tumor of the stomach: progresses in diagnosis and treatment. Acta Gastroenterol Belg. 76(4):403-6, 2013 Holdsworth CH et al: CT and PET: early prognostic indicators of response to imatinib mesylate in patients with gastrointestinal stromal tumor. AJR Am J Roentgenol. 189(6):W324-30, 2007 Lassau N et al: Gastrointestinal stromal tumors treated with imatinib: monitoring response with contrast-enhanced sonography. AJR Am J Roentgenol. 187(5):1267-73, 2006 Warakaulle DR et al: MDCT appearance of gastrointestinal stromal tumors after therapy with imatinib mesylate. AJR Am J Roentgenol. 186(2):510-5, 2006 Antoch G et al: Comparison of PET, CT, and dual-modality PET/CT imaging for monitoring of imatinib (STI571) therapy in patients with gastrointestinal stromal tumors. J Nucl Med. 45(3):357-65, 2004 Gayed I et al: The role of 18F-FDG PET in staging and early prediction of response to therapy of recurrent gastrointestinal stromal tumors. J Nucl Med. 45(1):17-21, 2004 Haider N et al: Gastric stromal tumors in children. Pediatr Blood Cancer. 42(2):186-9, 2004 Logrono R et al: Recent advances in cell biology, diagnosis, and therapy of gastrointestinal stromal tumor (GIST). Cancer Biol Ther. 3(3)251-8, 2004 Bechtold RE et al: Cystic changes in hepatic and peritoneal metastases from gastrointestinal stromal tumors treated with Gleevec. Abdom Imaging. 28(6):808-14, 2003 Besana-Ciani I et al: Outcome and long term results of surgical resection for gastrointestinal stromal tumors (GIST). Scand J Surg. 92(3):195-9, 2003 Burkill GJ et al: Malignant gastrointestinal stromal tumor: distribution, imaging features, and pattern of metastatic spread. Radiology. 226(2):52732, 2003 Connolly EM et al: Gastrointestinal stromal tumours. Br J Surg. 90(10):117886, 2003 Dong Q et al: Epithelioid variant of gastrointestinal stromal tumor: Diagnosis by fine-needle aspiration. Diagn Cytopathol. 29(2):55-60, 2003 Duffaud F et al: Gastrointestinal stromal tumors: biology and treatment. Oncology. 65(3):187-97, 2003 Frolov A et al: Response markers and the molecular mechanisms of action of Gleevec in gastrointestinal stromal tumors. Mol Cancer Ther. 2(8):699-709, 2003

Gastric GIST Stomach

(Left) Axial CECT shows an exophytic soft tissue density mass distorting the distal stomach and duodenum. (Right) Axial CECT in the same patient shows brisk enhancement of this mass with areas of necrosis, as well as prominent feeding vessels .

(Left) Axial CECT shows a polypoid, soft tissue density mass along the lesser curvature of the stomach. The large intraluminal component in this case makes distinction from a gastric carcinoma difficult. (Right) Axial CECT in the same patient shows a large cavitation within the mass communicating with the gastric lumen.

(Left) Axial CECT shows a large, exophytic, gastric gastrointestinal stromal tumor (GIST) arising from the greater curve of the stomach. It has a thick, mildly enhancing wall and a necrotic center . (Right) Axial fused PET/CT in the same case shows FDG uptake within the solid portion of this mass. FDG PET will show activity in the primary tumor and aids in the detection of metastatic disease. It can also detect early response to therapy before morphologic changes are seen in the tumor.

297

Stomach

Gastric Carcinoma KEY FACTS

TERMINOLOGY

PATHOLOGY

• Malignancy arising from gastric mucosa

• Risk factors ○ Helicobacter pylori (3-6x risk), pernicious anemia (2-3x risk) ○ Diet heavy in nitrites or nitrates; salted, smoked, poorly preserved food

IMAGING • Best diagnostic clue ○ Polypoid or circumferential mass with no peristalsis through lesion • Best imaging tool ○ Double-contrast upper GI series, CECT, EUS

TOP DIFFERENTIAL DIAGNOSES • • • • • • • •

Normal variant Benign gastric (peptic) ulcer Gastritis Gastric metastases and lymphoma Gastric stromal tumor (GIST) Caustic gastritis Pancreatitis (extrinsic inflammation) Ménétrier disease

(Left) Graphic shows a large intraluminal mass with a broad base and irregular surface. (Right) CECT in a 41year-old woman shows mural thickening of soft tissue density , representing an infiltrative gastric carcinoma.

(Left) More cephalad section in the same patient shows circumferential thickening of the gastric wall that severely limits distensibility. (Right) CT through the pelvis shows a collection of ascites and bilateral adnexal masses . The right adnexal mass is mostly cystic with a contrast-enhancing rim of soft tissue, while the left mass is more solid than cystic. At surgery, gastric carcinoma and bilateral ovarian metastases (Krukenberg tumors) were confirmed.

298

CLINICAL ISSUES • Most common signs/symptoms ○ Anorexia, weight loss, anemia, pain; can be asymptomatic • Diagnosis by endoscopic biopsy and histology

DIAGNOSTIC CHECKLIST • Image interpretation pearls ○ Can be ulcerative, polypoid, or infiltrative (scirrhous type) ± local and distant metastases ○ Beware of gastric fundus tumor simulating achalasia on esophagram

Gastric Carcinoma

Definitions • Malignancy arising from gastric mucosa

IMAGING General Features • Best diagnostic clue ○ Polypoid or circumferential mass with no peristalsis through lesion (at fluoroscopy) • Morphology ○ Polypoid, ulcerated, infiltrative lesions

Fluoroscopic Findings • 3 major fluoroscopic patterns on double-contrast upper GI series ○ Malignant ulcer – Irregular ulcer crater – Distortion or obliteration of surrounding areae gastricae – Nodular, irregular, clubbed, or amputated folds that do not extend to edge of ulcer crater – Ulcer does not project beyond expected contour of stomach (in profile) ○ Intraluminal mass • Gastric cancers are often scirrhous ○ Those arising in antrum may cause gastric outlet obstruction – Look for nodular thickened folds, absence of peristalsis ○ Linitis plastic ("leather bottle") – Small, nondistensible, nonperistaltic stomach – Caused by diffuse infiltration of gastric wall ○ Pseudoachalasia:Gastric fundus carcinoma may invade distal esophagus and destroy myenteric plexus – Resulting esophageal obstruction, dilated lumen, diminished peristalsis may be mistaken for primary achalasia – Distinction: Look for nodular folds, mass in gastric fundus

CT Findings • Primary tumor • Negative contrast agents (water or gas) facilitate visualization of lesions ○ Polypoid mass ± ulceration ○ Focal wall thickening with mucosal irregularity or focal infiltration of wall ○ Ulceration: Gas-filled ulcer crater within mass ○ Infiltrating carcinoma: Wall thickening with loss of normal rugal fold pattern – Wisp-like perigastric soft tissue stranding: Perigastric fat extension ○ Scirrhous carcinoma: Markedly enhancing thickened wall on dynamic CT ○ Mucinous carcinoma: attenuation of thickened wall ( mucin); calcification seen ○ Carcinoma of cardia: Irregular soft tissue thickening; lobulated mass • Hematogenous metastases ○ Liver 37%, lung 16%, bone 16%

○ All other sites are < 10% (brain, adrenal, pleural, etc.) • Peritoneal metastases ○ Seeding of peritoneal cavity is common – Malignant ascites and peritoneal nodules or masses ○ Krukenberg tumor: Metastases to ovaries via peritoneal seeding – Hematogenous spread to ovaries is less common • Lymphatic spread to perigastric nodes is common and early finding ○ Site of primary tumor influences nodal groups involved ○ Most common: Gastrohepatic ligament, celiac, and superior mesenteric nodes ○ Perigastric nodes > 6 mm are probably involved • Direct extension through peritoneal ligaments ○ Liver via gastrohepatic ligament ○ Spleen via gastrosplenic ligament ○ Transverse colon via gastrocolic ligament

Stomach

TERMINOLOGY

Ultrasonographic Findings • Endoscopic ultrasonography (EUS) ○ Carcinoma staging, assess depth of wall invasion and perigastric lymph nodes ○ Reported accuracy for T staging of 65-92%

Nuclear Medicine Findings • PET/CT ○ Signet cell, poorly differentiated, and mucinous types may not be FDG avid ○ Some studies suggest no improvement in staging with PET/CT over CT alone

Imaging Recommendations • Best imaging tool ○ Double-contrast barium study, CECT, EUS • Protocol advice ○ For CECT, distend stomach with water prior to scanning ○ Multiplanar reformations are key

DIFFERENTIAL DIAGNOSIS Normal Variant • Gastric wall at esophagogastric junction often appears thickened • Distending stomach with gas or fluid and placing patient in prone or left decubitus position will shows normal gastric wall

Benign Gastric (Peptic) Ulcer • Round ulcer, smooth mound of edema, smooth radiating folds to ulcer edge • Hampton line, ulcer collar, ulcer mound are classic features • Diagnosis by endoscopic biopsy

Gastritis • On upper GI series ○ Thickened folds, superficial erosions or deeper ulcerations • On CT ○ Submucosal thickening of water density (not soft tissue) • Granulomatous gastritis (Crohn disease) ○ Thickened nodular folds in antrum ○ Ram's horn sign: Smooth, funnel-shaped narrowing 299

Stomach

Gastric Carcinoma

Gastric Metastases and Lymphoma • Gastric metastases: Most common primary sites ○ Colon, malignant melanoma, breast, lung, pancreas – Can be focal masses (e.g., melanoma) or diffuse, even linitis plastica appearance (e.g., breast cancer) – Wall thickening is soft tissue density • Gastric lymphoma (e.g., non-Hodgkin B cell) ○ Stomach is most commonly involved organ in GI tract ○ Usual appearance: Circumferential mass that does not cause gastric outlet obstruction

Demographics

• Subacute or chronic phase resembles linitis plastica

• Age ○ Middle aged and elderly • Gender ○ M:F = 2:1 • Epidemiology ○ 3rd most common GI malignancy after colorectal and pancreatic carcinoma (in North America) – Uncommon and decreasing in USA but common in Japan, Chile, Finland, Poland, Iceland ○ Adenocarcinoma (95%) is most common primary gastric tumor

Pancreatitis (Extrinsic Inflammation)

Natural History & Prognosis

• Thickened gastric wall, peripancreatic inflammation

• Complications ○ Gastric outlet obstruction in antral carcinoma • Prognosis ○ 5-year survival rate – Early (85-100%) – Advanced (3-21%)

Gastrointestinal Stromal Tumor (GIST) • Large, lobulated submucosal mass ± cavitation • Intramural (50%), exogastric (35%), endogastric (15%)

Caustic Gastritis

Ménétrier Disease • Markedly thickened lobulated folds in gastric fundus and body, usually sparing antrum

PATHOLOGY General Features

Treatment

• Etiology ○ Diet heavy in nitrites or nitrates; salted, smoked, poorly preserved food ○ Risk factors: Helicobacter pylori, atrophic gastritis, pernicious anemia, adenomatous polyps, Ménétrier disease, partial gastrectomy (Billroth II), blood type A, smoking – H. pylori (3-6x risk), pernicious anemia (2-3x risk) ○ Environmental factors have major role in development of gastric cancer

• Radiotherapy, chemotherapy • Surgery: Subtotal or total gastrectomy

Staging, Grading, & Classification

• Can be ulcerative, polypoid, or infiltrative (scirrhous type) ± local and distant metastases • Beware of gastric fundus tumor simulating achalasia on esophagram ○ Causes esophageal obstruction, luminal narrowing, decreased peristalsi • Avoid mistaking normal thickening at esophagogastric junction for tumor ○ Distend stomach; place patient in prone or left decubitus position

• CT staging of gastric cancer ○ I: Intraluminal mass ○ II: Intraluminal mass, gastric wall thickness > 1 cm ○ III: Adjacent structures + lymph nodes ○ IV: Distant metastases • Nodal metastases, common sites: Hepatogastric, celiac

Gross Pathologic & Surgical Features • Polypoid, ulcerated, local, or diffuse infiltrative and rarely multiple lesions

Microscopic Features • • • •

Well-differentiated adenocarcinoma Signet ring cell, papillary, tubular, mucinous Early: Limited to mucosa and submucosa Advanced: Mucosa, submucosa, muscularis propria

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Anorexia, weight loss, anemia, pain; can be asymptomatic 300

○ Melena, enlarged left supraclavicular Virchow node • Lab data: Hypochromic, microcytic anemia; stool positive for occult blood • Diagnosis by endoscopic biopsy and histology

DIAGNOSTIC CHECKLIST Consider • Differentiate from other pathologies that mimic gastric cancer on imaging • Definitive diagnosis requires deep biopsy

Image Interpretation Pearls

SELECTED REFERENCES 1. 2. 3.

4.

Park K et al: Usefulness of combined PET/CT to assess regional lymph node involvement in gastric cancer. Tumori. 100(2):201-6, 2014 Oya H et al: Curative surgery for gastric cancer of the elderly in a Japanese regional hospital. Hepatogastroenterology. 60(127):1673-80, 2013 Shen C et al: Improved quality of life in patients with adenocarcinoma of esophagogastric junction after gastric tube reconstruction. Hepatogastroenterology. 60(128):1985-9, 2013 Shen Y et al: Evaluation of early gastric cancer at multidetector CT with multiplanar reformation and virtual endoscopy. Radiographics. 31(1):189-99, 2011

Gastric Carcinoma Stomach

(Left) Spot film from a doublecontrast upper GI series shows a mass as a filling defect in the barium pool on this supine film. (Right) Axial CECT in the same patient shows a large mass in the gastric fundus, with narrowing of the lumen.

(Left) Spot film from an upper GI series in a 56-year-old man with early satiety and weight loss shows nodular, markedly thickened folds throughout the fundus and body of the stomach, representing gastric carcinoma. (Right) Axial CECT in an 86-year-old man with early satiety and weight loss shows a thick-walled stomach with limited distensibility. Note the sharp transition from the thin-walled normal portion to the malignant infiltration, which shows soft tissue density , characteristic of malignancy.

(Left) Axial CECT shows a circumferential mass that narrows the lumen of the gastric antrum.. An irregular collection of gas and particulate material is noted within the antral mass, representing an ulcerated portion of the tumor. (Right) A coronal-reformatted CT in the same case shows the antral tumor with its central ulceration . A scirrhous circumferential antral cancer with a large surface ulceration was confirmed at gastrectomy.

301

Stomach

Gastric Carcinoma

(Left) Axial CECT in a 77-yearold man shows a large mass infiltrating and thickening the lesser curve from the gastric cardia to the pylorus. Liver and adrenal metastases are evident, along with regional lymphadenopathy . (Right) Axial CECT in the same patient reveals involvement of the splenic vein , which has resulted in splenic vein narrowing and perigastric collaterals . Celiac nodal metastases are also noted.

(Left) Axial CECT in a 71-yearold woman with early satiety, weight loss, and loss of appetite shows a distended stomach but a contracted antrum and thickened wall . Infiltration of the perigastric fat, as well as enlarged lymph nodes , indicate spread beyond the gastric wall. (Right) Film from an upper GI series in the same patient illustrates the antral constricting mass and partial outlet obstruction, along with destruction of the mucosal pattern of the stomach.

(Left) Axial CECT in an 81year-old woman with early satiety and weight loss shows soft tissue density infiltration of the wall of the distal stomach , with gastric outlet obstruction suggested by the presence of retained food within the stomach. Note the normal thin gastric wall for comparison. (Right) Gross pathology photograph of the resected specimen shows the scirrhous, fibrotic appearance of the gastric wall where it is infiltrated by the tumor.

302

Gastric Carcinoma Stomach

(Left) Spot film from an upper GI in an 82-year-old man with early satiety, loss of appetite, and weight loss shows a remarkably contracted and nondistensible stomach . Note the position of the gastroesophageal (GE) junction and pylorus . (Right) Axial CECT in the same patient demonstrates the constricted stomach . There is a surprising lack of signs of perigastric tumor spread or metastases. This patient underwent a complete gastrectomy.

(Left) Spot film from the esophagram in an 80-year-old woman with dysphagia shows moderate dilation and delayed emptying of the esophagus in the upright position. The lumen is abruptly and irregularly narrowed at the GE junction . (Right) Coronalreformatted CT section in the same patient shows a large gastric fundus mass that extends up into the cardia and distal esophagus. This is an example of pseudoachalasia due to gastric carcinoma.

(Left) Axial CECT section in the same patient shows more of the gastric cancer in addition to an hepatic metastasis . (Right) In the same case, an image from a fused PET/CT study demonstrates marked FDG avidity within the hepatic and gastric masses. In some reports, combined PET/CT has not shown superiority over CT alone in preoperative staging of gastric carcinoma.

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Stomach

Gastric Metastases and Lymphoma KEY FACTS

IMAGING

CLINICAL ISSUES

• Best diagnostic clue ○ Bull's-eye lesions on imaging • Best imaging tool ○ CECT with MPRs; barium (single or double) contrast studies

• Complications ○ Upper GI bleeding and perforation in ulcerated lesions ○ Antral lesion + pyloric extension: Outlet obstruction • Treatment ○ Radiation and/or chemotherapy; surgical resection of lesions for bleeding or perforation ○ Eradication of Helicobacter pylori for gastric lymphoma • Prognosis: Poor for gastric metastases; good for MALT lymphoma

TOP DIFFERENTIAL DIAGNOSES • • • •

Gastric carcinoma Gastric stromal tumor (GIST) Gastritis (erosive type) Pancreatitis (extrinsic inflammation)

PATHOLOGY • Gastric lymphoma is classified into 2 types based on pathology ○ Low-grade MALT lymphoma ○ High-grade or advanced non-Hodgkin lymphoma

(Left) Axial CECT in a 69-yearold man shows widespread metastases from the patient's known metastatic melanoma, including the gastric wall , lymph nodes , and omentum . (Right) Axial CECT in the same patient again illustrates classic widespread metastases from melanoma, here involving the small bowel , lymph nodes , and omentum , with both nodular and diffuse metastases seen. In addition, the left ureter was obstructed due to a ureteral/retroperitoneal metastasis.

(Left) Upper GI in a 70-year-old man with weight loss and dyspepsia reveals distortion and blunting of the gastric folds. In spite of what appears to be diffuse involvement of the stomach, there is no outlet obstruction, and the stomach is distensible. (Right) Axial CECT in the same patient shows massive thickening of the gastric wall of soft tissue attenuation. Note the extensive regional lymphadenopathy and omental tumor deposits . These findings are typical of primary gastric lymphoma.

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DIAGNOSTIC CHECKLIST • Check for history or evidence of of primary cancer or H. pylori gastritis • Image interpretation pearls ○ Imaging important to suggest and stage malignancy, but biopsy is required

Gastric Metastases and Lymphoma

Definitions • Metastases from primary extragastric cancer • Lymphoma: Malignant gastric tumor of B lymphocytes

IMAGING General Features • Best diagnostic clue ○ Bull's-eye lesions on CT or upper GI series

Fluoroscopic Findings • Fluoroscopic-guided barium study ○ Malignant melanoma metastases – Solitary or multiple discrete submucosal masses – Bull's-eye or "target" lesions: Centrally ulcerated submucosal masses ○ Breast carcinoma metastases – Lobular breast cancer: Linitis plastica or "leather bottle" appearance (loss of distensibility of antrum and body + thickened irregular folds) ○ Esophageal carcinoma – Large polypoid/ulcerated mass in gastric fundus ○ Pancreatic carcinoma – Often indents, rarely invades stomach – Direct invasion: Spiculated mucosal folds, nodular mass effect, ulceration, obstruction ○ Peritoneal and omental metastases may involve stomach – Ovarian cancer and other primaries that cause peritoneal metastases – Transverse colon cancer may invade stomach via gastrocolic ligament – Most common sign is intramural mass along greater curvature ○ Low-grade MALT lymphoma – Rounded, confluent nodules of low-grade lymphoma □ Mimic enlarged areae gastricae of Helicobacter pylori gastritis – Shallow, irregular ulcers with nodular surrounding mucosa ○ High-grade/advanced lymphoma – Infiltrative lesions: Massively enlarged folds with distorted and nodular contour □ Stomach remains pliable and distensible – Polypoid lymphoma: Lobulated intraluminal mass – Nodular lesions: Submucosal nodules or masses often ulcerate, resulting in bull's-eye or "target" lesions

CT Findings • Demonstration of lesions facilitated by distention of stomach by water and gas • Multiplanar reformation (MPRs) very useful to judge full extent of disease and relation to adjacent organs, nodes • Hematogenous spread of metastases to stomach ○ Malignant melanoma – Bull's-eye or "target" lesions, nodular intramural cavitated lesions ○ Breast cancer: Linitis plastica or "leather bottle" – Markedly thickened gastric wall with enhancement, folds preserved

– Mimics primary scirrhous carcinoma of stomach • Direct invasion or lymphatic spread to stomach ○ Distal esophageal carcinoma – Polypoid, lobulated mass in gastric fundus – Indistinguishable from primary gastric carcinoma ○ Pancreatic carcinoma – Irregular extrinsic gastric compression – Pancreatic tumor will be evident ○ Transverse colon cancer gastrocolic ligament greater curvature – Thickened wall or mass in greater curvature ± gastrocolic fistulous tract ○ Omental and peritoneal metastases: Ovary, uterus, pancreas, breast – Can be seen as small as 1 cm – Lacy reticular pattern to bulky masses (omental cake) displace and indent gastric wall • Gastric lymphoma ○ Markedly thickened gastric wall, regional or widespread adenopathy ○ Mural density of stomach is soft tissue (not water density as in gastritis) ○ Rarely causes linitis plastica or gastric outlet obstruction ○ Transpyloric spread into duodenum may be seen

Stomach

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Endoscopic ultrasonography (EUS) – Hypoechoic mass disrupting normal wall layers

Imaging Recommendations • Best imaging tool ○ Helical CT; barium (single or double) contrast studies ○ EUS for depth of invasion and guided biopsy

DIFFERENTIAL DIAGNOSIS Gastric Carcinoma • Polypoid, ulcerated, infiltrative types indistinguishable from gastric metastases and lymphoma • Linitis plastica: Primary scirrhous type mimics metastatic breast cancer • Loss of distensibility in scirrhous type differentiates from non-Hodgkin lymphoma (NHL)

Gastric Stromal Tumor (GIST) • Usually occur as solitary lesions, mostly exophytic • Also produce giant, cavitated lesions

Gastritis (Erosive Type) • Multiple punctate barium collections surrounded by thin radiolucent halos of edematous mucosa • Submucosal layer of gastric wall is near water density

Pancreatitis (Extrinsic Inflammation) • Changes in greater curvature or posterior wall of stomach mimic omental metastatic invasion • Peripancreatic inflammation evident on CT

Gastric Pseudolymphoma • Rare extensive benign reactive hyperplasia within gastric wall • Difficult or impossible to diagnose by imaging alone 305

Stomach

Gastric Metastases and Lymphoma

General Features • Etiology ○ Gastric metastases – Malignant melanoma; carcinoma of breast, lung, pancreas, colon, esophagus ○ Gastric lymphoma – Arise from mucosa-associated lymphoid tissue (MALT) in patients with chronic H. pylori gastritis containing cytotoxin-associated antigen (CagA) □ May be cured with eradication of H. pylori – Primary: NHL more common than secondary involvement – Secondary lymphoma (generalized lymphoma) □ These are treated with radiation &/or systemic chemotherapy like other high grade lymphomas • Associated abnormalities ○ Extragastric primary carcinoma in gastric metastases ○ Generalized adenopathy in secondary lymphoma

Staging, Grading, & Classification • Classified into 2 types based on pathology ○ Low-grade MALT lymphoma (most common type) – Marginal zone B-cell NHL ○ High-grade or advanced lymphoma – Diffuse large B-cell NHL • Ann Arbor staging of primary lymphoma ○ Stage I: Involve gastric wall ○ Stage II: Involve regional lymph nodes in abdomen ○ Stage III: Nodes above and below diaphragm ○ Stage IV: Widely disseminated lymphoma

Gross Pathologic & Surgical Features • Solitary/multiple; polypoid, ulcerated, cavitated masses or "leather bottle" appearance of stomach

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pain, weight loss, palpable mass; can be asymptomatic ○ Hematemesis, melena, acute abdomen (perforation)

Demographics • Age ○ Usually middle-aged and elderly • Gender ○ Metastases (M = F), lymphoma (M > F) • Epidemiology ○ Gastric lymphoma – Stomach is most frequently involved part of GI tract □ Constitutes 50% of all GI tract lymphomas, 25% of extranodal lymphomas – > 50% of cases are primary gastric lymphoma – 3-5% of all gastric malignancies ○ Gastric metastases: Seen in < 2% who die of cancer ○ Most patients with gastric metastases have known primary – Occasionally may occur as initial manifestation of occult primary tumor 306

– Breast and kidney carcinoma can metastasize to stomach many years after primary treatment

PATHOLOGY

Natural History & Prognosis • Metastases to stomach ○ Prognosis depends on effective treatment of primary tumor and its metastases ○ Prognosis is generally poor • MALT lymphoma has much better prognosis than primary gastric or secondary lymphoma ○ May be cured in about 70% by eradication of H. pylori alone • Complications ○ Upper GI bleeding and perforation in ulcerated lesions ○ Antral lesion + pyloric extension: Outlet obstruction

Treatment • Eradication of H. pylori • Radiation &/or chemotherapy, surgical resection of lesions if upper GI bleed or perforation

DIAGNOSTIC CHECKLIST Consider • Check for history or evidence of primary cancer or H. pylori gastritis

Image Interpretation Pearls • Overlapping radiographic features of gastric metastases, lymphoma, and primary carcinoma • Imaging important to suggest and stage malignancy, but biopsy is required for diagnosis

SELECTED REFERENCES 1. 2.

Fischbach W: MALT lymphoma: forget surgery? Dig Dis. 31(1):38-42, 2013 Burke JS: Lymphoproliferative disorders of the gastrointestinal tract: a review and pragmatic guide to diagnosis. Arch Pathol Lab Med. 135(10):1283-97, 2011 3. Kobayashi A et al: MR imaging of reactive lymphoid hyperplasia of the liver. J Gastrointest Surg. 15(7):1282-5, 2011 4. Hargunani R et al: Cross-sectional imaging of gastric neoplasia. Clin Radiol. 64(4):420-9, 2009 5. Gollub MJ: Imaging of gastrointestinal lymphoma. Radiol Clin North Am. 46(2):287-312, ix, 2008 6. Santacroce L et al: Helicobacter pylori infection and gastric MALTomas: an up-to-date and therapy highlight. Clin Ter. 159(6):457-62, 2008 7. Ba-Ssalamah A et al: Dedicated multidetector CT of the stomach: spectrum of diseases. Radiographics. 23(3):625-44, 2003 8. Horton KM et al: Current role of CT in imaging of the stomach. Radiographics. 23(1):75-87, 2003 9. Park MS et al: Radiographic findings of primary B-cell lymphoma of the stomach: low-grade versus high-grade malignancy in relation to the mucosaassociated lymphoid tissue concept. AJR Am J Roentgenol. 179(5):1297-304, 2002 10. Fishman EK et al: CT of the stomach: spectrum of disease. Radiographics. 16(5):1035-54, 1996 11. McDermott VG et al: Malignant melanoma metastatic to the gastrointestinal tract. AJR Am J Roentgenol. 166(4):809-13, 1996 12. Feczko PJ et al: Metastatic disease involving the gastrointestinal tract. Radiol Clin North Am. 31(6):1359-73, 1993

Gastric Metastases and Lymphoma Stomach

(Left) Axial CECT in a 57-yearold man with a known history of malignant melanoma, now presenting with weight loss and dyspepsia, shows metastases to the liver and gallbladder . The stomach is not well distended or easily assessed. (Right) Upper GI in the same patient illustrates classic bull's-eye lesions , consisting of small, intramural masses with a central ulceration.

(Left) Axial CECT in a 75-yearold man who presented with weight loss and dyspepsia demonstrates a soft tissue density mass that diffusely infiltrates the gastric wall. There is no outlet obstruction. (Right) Upper GI in the same patient reveals marked thickening and blunting of the gastric folds but nearly normal distensibility and no obstruction, findings typical of lymphoma.

(Left) Axial CECT in an 84year-old woman with a known history of breast cancer and a recent onset of early satiety and nausea reveals gastric distension and retention of food. The antrum is nondistensible and is infiltrated with a soft tissue density mass . (Right) Upper GI in the same patient confirms a scirrhous lesion of the gastric antrum causing delayed gastric emptying. These imaging findings are indistinguishable from primary gastric carcinoma.

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SECTION 5

Duodenum

Introduction and Overview Imaging Approach to the Duodenum

310

Normal Variants and Artifacts Duodenal Flexure Pseudotumor

314

Congenital Duodenal Diverticulum

315

,QƮDPPDWLRQ Duodenitis Duodenal Ulcer Brunner Gland Hyperplasia

316 318 322

Vascular Disorders SMA Syndrome

324

Trauma Gastroduodenal Trauma

326

Treatment Related Aortoenteric Fistula

328

Benign Neoplasms Duodenal Polyps

330

Malignant Neoplasms Duodenal Carcinoma Duodenal Metastases and Lymphoma

334 338

Duodenum

Imaging Approach to the Duodenum

Duodenal Anatomy and Terminology The duodenal bulb is the triangular first portion of the duodenum. It is suspended by the hepatoduodenal ligament, which also contains the bile duct, portal vein, and hepatic artery. The bulb is the only intraperitoneal portion of the duodenum. The descending duodenum is the second portion and is the site of the major pancreaticobiliary papilla (of Vater), the entry of the common bile and pancreatic ducts. The transverse duodenum is its third portion, and it crosses between the aorta and the superior mesenteric vessels. The ascending duodenum is the fourth portion, ending at the duodenojejunal junction, which is fixed in place by the suspensory ligament of the duodenum (ligament of Treitz). The duodenojejunal junction usually lies at about the same level as the pylorus and the T12 vertebra.

Imaging Anatomy The duodenal wall consists of 4 layers: The mucosa, submucosa, circular, and longitudinal smooth muscle. Brunner glands secrete mucus and alkaline fluid with proteolytic enzymes. These are most prominent within the proximal duodenum and may enlarge to simulate multiple polyps (Brunner gland hypertrophy) or may develop into a benign neoplastic mass (Brunner gland adenoma). The second and third portions of the duodenum are closely attached to the pancreatic head, and resection of either organ generally requires resection of both, known as a pancreaticoduodenectomy (Whipple procedure). The duodenum occupies the anterior pararenal space of the retroperitoneum along with the pancreas and vertical colon segments. Inflammatory, or less commonly malignant processes, affecting one of these organs often spread to affect the others. Duodenal ulcers and erosions are common, with a multifactorial etiology, including Helicobacter pylori infection. Erosion of the duodenal mucosa makes it vulnerable to the caustic effects of acid and digestive enzymes produced by the stomach. The second portion of duodenum lies just anterior to the right renal hilum. Inflammation originating in the duodenum (perforated ulcer) or pancreatic head (pancreatitis) may extend into the right perirenal space, potentially simulating primary renal inflammation. Duodenal ulcers may perforate, often resulting in collections of gas and fluid that are both intra- and retroperitoneal, reflecting the dual compartment location of the duodenum. Congenital diverticula commonly arise from the second and third portions of the duodenum and are usually of no clinical concern. A fluid-filled diverticulum could be mistaken for a cystic pancreatic mass. Periampullary diverticula may be associated with biliary disease and are prone to iatrogenic perforation if endoscopic papillotomy is performed. Diverticula may also perforate spontaneously or as the result of feeding tube placement. Duodenal tumors are uncommon relative to the rest of the GI tract and are often associated with various syndromes. Patients with Gardner syndrome, for example, have an increased prevalence of duodenal adenomas and carcinomas, 310

as well as ampullary carcinomas. Multiple endocrine neoplasia type 1 (MEN1) is associated with duodenal carcinoid tumors, in addition to tumors of the parathyroid, pancreas, and pituitary. The third portion of the duodenum is adjacent to the aorta and often lies at the proximal end of abdominal aortic aneurysms. Spontaneously, or more commonly following surgical or endovascular stent graft repair of an aneurysm, a fistula between the aorta and duodenum may form (aortoenteric fistula), often with fatal consequences.

Imaging Protocols Air-contrast upper GI series remains the most accurate imaging test for detecting mucosal erosions, ulcers, or polypoid lesions, although its use for these indications has decreased precipitously with increased use of endoscopy. Fluoroscopic studies may also be employed to evaluate functional abnormalities of the duodenum, such as the SMA syndrome. A "megaduodenum" may also result from scleroderma, and the duodenum is often involved in patients with celiac disease.

Differential Diagnosis Duodenal Intramural or Extrinsic Mass Common • Pancreatic pseudocyst • Pancreatic ductal carcinoma • Cholecystitis • Gallbladder carcinoma Less Common • Hepatomegaly • Duodenal hematoma and laceration • Annular pancreas • Pancreatic tumors, other: Pancreatic islet cell tumors, serous cystadenoma (pancreas) • Duodenal masses: Carcinoma, metastases and lymphoma, gastrointestinal stromal tumor (GIST) • Groove pancreatitis • Colon carcinoma • Kidney masses: Renal cyst, renal cell carcinoma Rare but Important • Choledochal cyst • Duplication cyst Dilated Duodenum Common • Ileus • Small bowel obstruction • Pancreatitis, acute • SMA syndrome • Post-vagotomy • Scleroderma, intestinal • Celiac disease Less Common • Strongyloides • Zollinger-Ellison syndrome Thickened Duodenal Folds Common • Duodenitis • Duodenal ulcer • Brunner gland hyperplasia • Acute pancreatitis • Duodenal hematoma and laceration • Chronic renal failure

Imaging Approach to the Duodenum

Duodenal Filling Defects Common • Prolapsed antral mucosa • Flexural pseudotumor (mimic) • Duodenal polyps • Brunner gland hyperplasia • Pancreatic ductal carcinoma • Duodenal lipoma

• • • • •

Duodenum

Less Common • Zollinger-Ellison syndrome • Opportunistic intestinal infections • Caustic gastroduodenal injury • Crohn disease • Celiac disease • Metastases and lymphoma • Duodenal varices

GIST Ampullary tumor Hamartomatous polyposis Gardner syndrome Choledochal cyst

Rare but Important • Mesenchymal tumor • Duplication cyst • Carcinoid tumor

Less Common • Duodenal hematoma • Ectopic gastric mucosa • Duodenal carcinoma • Metastases and lymphoma

(Left) The duodenum is retroperitoneal, except for the bulb (1st portion) . The 3rd portion of duodenum crosses in front of the aorta and behind the superior mesenteric vessels . (Right) The 2nd portion of duodenum is attached to the pancreatic head and lies in close proximity to the right renal hilum. The ampulla of Vater lies along the medial wall of the 2nd duodenum. The hepatoduodenal ligament attaches the duodenum to the porta hepatic and contains the bile duct, portal vein, and hepatic artery.

(Left) Spot film from an upper GI series shows a typical diverticulum extending from the medial border of the 2nd portion of the duodenum. (Right) Axial CT in the same patient shows an air-fluid level within the duodenal diverticulum . A completely fluid-filled diverticulum may mimic a cystic mass in the head of the pancreas.

311

Duodenum

Imaging Approach to the Duodenum

(Left) Film from an upper GI series in a patient with SMA syndrome shows the straight line demarcation of the midline duodenum, with dilation of the upstream duodenal lumen . The remainder of the small bowel is normal. (Right) Film from an upper GI series in a patient with scleroderma shows a "megaduodenum" . Dilation of the small bowel lumen and a "hidebound" appearance of the small bowel folds (thin and closely spaced) are typical features of this disease.

(Left) Film from an upper GI series shows multiple small polypoid masses in the duodenal bulb and descending duodenum. Endoscopic biopsy revealed hyperplasia and elements of hamartoma arising from Brunner glands. (Right) Upper GI series in a young patient with duodenal carcinoma and Gardner syndrome shows a large mass filling much of the 2nd and 3rd portions of the duodenum. Note the "apple core" appearance, similar to that of colon cancer.

(Left) Spot film from an upper GI series shows a mass causing abrupt narrowing of the duodenal lumen and irregularity or destruction of the duodenal mucosa. (Right) Coronal CECT in the same patient shows a soft tissue density mass within the duodenal lumen. The mass was resected and proved to be a large adenomatous polyp with foci of frank carcinoma.

312

Imaging Approach to the Duodenum Duodenum

(Left) CT shows a thick-walled stomach with extraluminal oral contrast medium and gas tracking from the duodenal bulb. Surgery confirmed a perforated ulcer of the duodenal bulb and gastritis. (Right) Axial CECT shows gas in the perirenal space, surrounding the kidney . While this might suggest a primary renal process, the correct diagnosis of a perforated duodenal ulcer is made by the finding of extraluminal gas surrounding the 2nd and 3rd portions of duodenum with its thickened wall.

(Left) Axial CECT in an elderly man with nausea and early satiety shows that the stomach, duodenal bulb , and pancreatic head appear normal. (Right) Axial CECT in the same patient shows a large, heterogeneously hypervascular mass arising from the duodenum.

(Left) Coronal MIP reconstruction in the same patient shows the exophytic, hypervascular mass arising from the duodenum. (Right) Another MIP reconstruction in the same patient shows foci of necrosis and calcification within the mass . All features are characteristic of a duodenal GIST, confirmed at surgery. The duodenum is one of the more common locations for GI stromal tumors.

313

Duodenum

Duodenal Flexure Pseudotumor KEY FACTS

TERMINOLOGY • Duodenal pseudolesion • Duodenal flexure pseudolesion • Redundant mucosa within duodenum that mimics duodenal polypoid mass

IMAGING • Redundant mucosa appears as filling defect within lumen at junction of 1st and 2nd portions of duodenum ○ At angle between bulb and descending duodenum ○ Acute angulation as duodenum becomes retroperitoneal, accentuates fold • May even simulate ulcerated mass, with barium trapped between mucosal folds • Changeable appearance on upper GI fluoroscopy ○ May disappear on upright or left decubitus positioning, or with compression ○ Normal peristalsis • Can simulate polypoid mass on CT as well

(Left) Axial CECT shows an apparent soft tissue density mass within the proximal duodenum. (Right) Coronal CECT in the same patient shows the same apparent soft at the tissue density mass junction of the 1st and 2nd portions of the duodenum. This classic location should suggest the diagnosis. CT has the disadvantage of not allowing real-time evaluation.

(Left) Spot film from an upper GI series shows acute angulation of the duodenum at the junction of the apex of the bulb and the 2nd portion of the duodenum. The duodenal flexure creates folding and redundancy of the wall , accounting for the pseudotumor. (Right) Overhead film from the upper GI series shows that the pseudolesion is redundant duodenal mucosa along the inner aspect of the flexure between the duodenal bulb and descending duodenum. Upper endoscopy confirmed normal duodenum.

314

○ CT has disadvantage of not allowing real-time evaluation of changes with peristalsis or different positions ○ Pseudolesion has same imaging characteristics (enhancement) as remainder of duodenal mucosa • Best imaging test: Upper GI series with spot films and fluoroscopy ○ Characteristic location and changeable appearance are key observations ○ View in multiple obliquities: Upright and prone ○ View with and without compression • Endoscopy can confirm diagnosis ○ Usually unnecessary

Duodenal Diverticulum

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• True diverticula ○ Location: Medial (70%) descending duodenum in periampullary region, 3rd or 4th portion (26%), lateral (4%) descending duodenum ○ Filling defects within diverticulum (food and gas) ○ CT: Fluid-filled diverticulum may simulate cystic mass in pancreatic head ○ CT usually shows air-fluid level within diverticulum • Intraluminal diverticula ○ "Windsock" appearance: Barium-filled, globular structure of variable length, originating in 2nd portion of duodenum, fundus extending into 3rd portion; outlined by thin, radiolucent line ○ CT: Contrast medium and gas within diverticulum, surrounded by contrast in duodenal lumen; separated by thin wall of diverticulum

• Pancreatic pseudocyst • Pancreatic cystic tumor • Perforated duodenal ulcer

Duodenum

KEY FACTS

CLINICAL ISSUES • Periampullary diverticula ○ May predispose to biliary sphincter incompetence, reflux, biliary stones ○ Makes endoscopic sphincterotomy more difficult & dangerous • Perforation (duodenal diverticulitis) ○ Symptoms and signs are indistinguishable from perforated ulcer or pancreatitis ○ May occur spontaneously or following instrumentation (e.g., endoscopy or passage of feeding tube)

(Left) Film from an upper GI series in an asymptomatic 75year-old man shows a large, featureless outpouching arising from the upper margin of the 3rd portion of the duodenum. (Right) Axial CT in the same patient shows the diverticulum filled with food debris and gas. This could be confused with a gascontaining abscess, but the absence of symptoms or inflammatory changes on CT makes the diagnosis.

(Left) Axial CT in the same patient shows the gas collection is immediately medial & posterior to the inflamed duodenum . At surgery, perforation of a duodenal diverticulum was found, which may occur spontaneously or after instrumentation of the upper GI tract. (Right) Film from an upper GI series shows intraluminal diverticulum having a "windsock" appearance within the lumen of the duodenum.

315

Duodenum

Duodenitis KEY FACTS

IMAGING

CLINICAL ISSUES

• Best imaging tool ○ Upper GI, CECT • Best diagnostic clue ○ Upper GI: Aphthous ulcers, fold thickening, luminal spasm of duodenal bulb (± gastric antrum) ○ CECT: Mural thickening of duodenum ± adjacent inflammation

• Most common signs/symptoms ○ Abdominal pain, nausea, vomiting • Other signs/symptoms ○ Gastrointestinal bleeding with deeper ulceration • Epidemiology ○ Helicobacter pylori infection and NSAID use • Treated with proton-pump inhibitors (plus antibiotics for H. pylori)

TOP DIFFERENTIAL DIAGNOSES • Cholecystitis • Pancreatitis • Ureteral colic

PATHOLOGY • Gastritis commonly coexists with duodenitis ○ Similar findings of mucosal erosions, fold thickening, luminal spasm

(Left) Spot film from an upper GI series shows aphthous ulcers in the gastric antrum and duodenal bulb, along with thickened duodenal folds , classic features of duodenitis and gastritis. (Right) Spot film from an upper GI series shows nodular fold thickening and lack of distensibility in the gastric antrum due to gastritis.

(Left) Another spot film from the upper GI series shows spasm and fold thickening of the duodenum , due to duodenitis. (Right) Axial CECT in the same patient shows luminal narrowing and mural thickening of the 2nd portion of duodenum, with surrounding inflammation due to duodenitis.

316

DIAGNOSTIC CHECKLIST • Duodenitis often coexists with gastritis • Symptoms are indistinguishable from peptic ulcers ○ Presence of only superficial (aphthous) erosions and fold thickening distinguishes duodenitis from duodenal ulcer • Diagnosis usually established by endoscopy

Duodenitis

Definitions • Duodenal inflammation from any cause

IMAGING General Features • Best diagnostic clue ○ Upper GI: Aphthous ulcers in duodenal bulb; fold thickening in antrum and duodenal bulb ○ CECT: Mural thickening of duodenum ± adjacent inflammation • Morphology ○ Discrete erosions with surrounding mound of edema in ring-like fashion

Imaging Recommendations • Best imaging tool ○ Upper GI, CECT • Protocol advice ○ Oral and IV contrast

Fluoroscopic Findings • Upper GI ○ Duodenal spasm, fold thickening ○ Superficial or deep ulcerations ○ Delayed gastric emptying or outlet obstruction

CT Findings • CECT ○ Duodenal narrowing, fold thickening, gastric distension with air or fluid ○ Ectopic gas or fluid with perforation ○ Extravasation of oral contrast into anterior pararenal space or peritoneal cavity ○ Fluid adjacent to thickened duodenum

DIFFERENTIAL DIAGNOSIS Cholecystitis • Gallstones on US or CT, stone impacted in gallbladder neck, mural thickening > 3 mm • Positive sonographic Murphy sign • Pericholecystic fat stranding in omentum on CECT

Pancreatitis • Diffuse or focal pancreatic enlargement • Peripancreatic fluid or infiltration

– Crohn disease – Radiation therapy – Pancreatitis – Viral or other bacterial infection • Associated abnormalities ○ Gastritis commonly coexists with duodenitis – Similar findings of mucosal erosions, fold thickening, luminal spasm

Gross Pathologic & Surgical Features • Inflammation of mucosa and submucosal edema • Superficial (aphthous) erosions or deep ulcers

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, nausea, vomiting • Other signs/symptoms ○ Gastrointestinal bleeding with deeper ulceration

Demographics • Age ○ Usually > 40 years old ○ Children can be affected, especially with causes other than H. pylori infection • Epidemiology ○ H. pylori infection ○ Increases with age – 20% occurrence rate at age 20, 40% occurrence rate at age 40, 60% occurrence rate at age 60

Treatment • H. pylori treated with antibiotics and proton-pump inhibitors (PPIs) • Peptic ulcer disease treated with PPIs alone

DIAGNOSTIC CHECKLIST Consider • Duodenitis often coexists with gastritis • Symptoms are indistinguishable from peptic ulcers ○ Diagnosis usually established by endoscopy

Image Interpretation Pearls • Presence of only superficial (aphthous) erosions and fold thickening distinguishes duodenitis from duodenal ulcer

SELECTED REFERENCES

Ureteral Colic

1.

• Nephromegaly, hydronephrosis, high-attenuation stone in ureter • Perirenal fluid due to forniceal rupture

2. 3.

PATHOLOGY General Features • Etiology ○ Helicobacter pylori infection is most common etiology ○ Nonsteroidal anti-inflammatory drug (NSAID) use is next most common cause ○ Much less common causes

Duodenum

TERMINOLOGY

4. 5.

Sugimoto S et al: Cytomegalovirus duodenitis associated with acquired immunodeficiency syndrome. Dig Endosc. 25(3):337-8, 2013 Esmadi M et al: Sarcoidosis: an extremely rare cause of granulomatous enterocolitis. J Gastrointestin Liver Dis. 21(4):423-5, 2012 Chang CH et al: Risk of hospitalization for upper gastrointestinal adverse events associated with nonsteroidal anti-inflammatory drugs: a nationwide case-crossover study in Taiwan. Pharmacoepidemiol Drug Saf. 20(7):763-71, 2011 Kim SH et al: Gastrointestinal tract perforation: MDCT findings according to the perforation sites. Korean J Radiol. 10(1):63-70, 2009 Hashash JG et al: Acute NSAID-related transmural duodenitis and extensive duodenal ulceration. Clin Ther. 29(11):2448-52, 2007

317

Duodenum

Duodenal Ulcer KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Mucosal erosion of duodenum

• Duodenal inflammation • Duodenal stricture • Duodenal carcinoma

IMAGING • 95% of ulcers are in duodenal bulb, 5% postbulbar • Upper GI series: Sharply marginated barium collection with folds radiating to edge of ulcer crater ○ Deformity of bulb (edema and spasm and scarring) ○ Pseudodiverticula balloon-out between areas of fibrosis and spasm ○ "Cloverleaf" deformity of bulb due to pseudodiverticula • CT with IV and oral contrast medium for diagnosis of perforation ○ Wall thickening, luminal narrowing of duodenum ○ Extraluminal intra- or retroperitoneal gas ± enteric contrast medium

(Left) Graphic illustrates a duodenal ulcer with a deformed bulb due to converging folds and spasm. (Right) Film from an upper GI series shows a "cloverleaf" deformation of the duodenal bulb, with the ulcer at the center of the cloverleaf. The other lobes of the cloverleaf are the duodenal bulb fornices or recesses. The pylorus is marked for orientation.

(Left) Axial CECT in a 42-yearold man presenting with acute severe abdominal pain and guarding shows extensive free intraperitoneal gas from a perforated duodenal ulcer. (Right) Axial CECT in the same patient demonstrates a thickened gastric wall , probably due to gastritis. Ventral to the duodenal bulb and antrum are small collections of extraluminal gas and oral contrast medium that confirm an ulcer as the source of perforation.

318

CLINICAL ISSUES • 2-3x more frequent than gastric ulcers • Burning, gnawing, or aching pain at epigastrium 2-4 hours after meals, relieved by antacids/food • Pain episodes occurring in clusters of days to weeks followed by longer pain-free intervals

DIAGNOSTIC CHECKLIST • Barium upper GI series and CT are complementary in diagnosis of ulcers and complications • Eradication of Helicobacter pylori is 1st step of treatment ○ Proton-pump inhibitors are also effective • Effective medical treatment has made surgical treatment much less common

Duodenal Ulcer

Synonyms • Peptic ulcer disease

Imaging Recommendations

Definitions

• Best imaging tool ○ Fluoroscopic-guided double-contrast barium studies ○ CT with IV and oral contrast medium for diagnosis of perforation • Protocol advice ○ Prone compression views at fluoroscopy to observe anterior wall ulcers ○ "Positive" oral contrast medium helps confirm perforation on CT

• Mucosal erosion of duodenum

IMAGING General Features • Best diagnostic clue ○ Sharply marginated barium collection with folds radiating to edge of ulcer crater on upper GI series • Location ○ 95% of ulcers are in duodenal bulb, 5% postbulbar – Bulbar ulcers: Apex, central portion, or base of bulb – Postbulbar ulcers: Medial wall of proximal descending duodenum above papilla of Vater • Size ○ Most ulcers are < 1 cm at time of diagnosis • Morphology ○ Round or ovoid barium collections ○ 5% of duodenal ulcers have linear configuration

Fluoroscopic Findings • Fluoroscopic-guided double-contrast barium studies ○ Bulbar ulcers – Persistent, small, round, ovoid or linear ulcer niche – Smooth, radiolucent ulcer mound of edematous mucosa – Radiating folds converge centrally at edge of ulcer crater – Ring shadow: Barium-coating rim of unfilled anterior wall ulcer crater (air-contrast view) – Deformity of bulb (edema and spasm and scarring) – Residual depression of central portion of scar mimics active ulcer crater – Pseudodiverticula balloon out between areas of fibrosis and spasm – "Cloverleaf" deformity of bulb due to pseudodiverticula ○ Postbulbar ulcers – Smooth, rounded indentation on wall opposite ulcer crater (edema and spasm) – Ring stricture: Eccentric narrowing (scarring) ○ Giant duodenal ulcers (> 2 cm) – Always located in duodenal bulb – Virtually replaces bulb, mistaken for scarred or normal bulb – Key clue: Fixed or unchanging configuration – Focal narrowing outlet obstruction (edema and spasm)

CT Findings • CECT (with water-soluble oral contrast) ○ Signs of penetration and perforation – Wall thickening, luminal narrowing of duodenum – Infiltration of surrounding fat or organs (pancreas) – Extraluminal intra- or retroperitoneal gas ± enteric contrast medium

Duodenum

– Presence of intra- and extraperitoneal gas in upper abdomen is essentially diagnostic of perforated duodenum

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Duodenal Inflammation • Duodenitis: Inflammation without frank ulceration • Crohn disease ○ Usually gastric antral involvement ○ Thickened, nodular folds, "cobblestone" appearance ○ 1 or more strictures in 2nd or 3rd portions of duodenum marked obstruction, proximal dilatation (megaduodenum) • Tuberculosis ○ Usually with gastric antral involvement ○ Ulcers, thickened folds, narrowing, or fistula ○ Enlarged lymph nodes adjacent to duodenum narrowing, obstruction of lumen

Duodenal Stricture • Pancreatitis ○ Thickened folds associated with medial compression, widening of duodenal sweep ○ Diagnosis of pancreatitis is made with CT and clinical findings • Gallstone erosion into duodenum ○ Radiolucent duodenal filling defect (stone) ○ Mucosal inflammation, ulceration, hemorrhage, perforation, obstruction ○ Barium reflux into gallbladder, bile ducts

Duodenal Carcinoma • • • •

< 1% of all gastrointestinal cancers Postbulbar location at or distal to papilla of Vater Polypoid, ulcerated, or annular lesions Narrowed lumen with thickened wall

Duodenal Diverticulum • Common incidental finding on barium studies • Most often located on medial border of descending duodenum, periampullary region • Smooth, rounded outpouching from medial border of descending duodenum • Configuration may change during course of study • Differentiate from postbulbar ulcers by change in shape and lack of inflammatory reaction

Extrinsic Invasion • Pancreatic carcinoma ○ Widening of duodenal sweep on upper GI ○ Diagnosis made by CT, EUS, and clinical findings 319

Duodenum

Duodenal Ulcer

– e.g., hypodense mass with obstruction of pancreatic and bile ducts • Gallbladder carcinoma ○ Compression of bulb or proximal duodenum ○ CT shows mass and thickening of gallbladder wall • Metastases to duodenum ○ Multiple submucosal masses or bull's-eye lesion ○ CT and clinical features allow distinction from duodenal ulcer

Duodenal Hematoma • Well-circumscribed intramural masses with discrete margins stenosis, obstruction • Diffuse hemorrhage thickened, spiculated folds or thumbprinting

PATHOLOGY General Features • Etiology ○ 2 major risk factors: Helicobacter pylori (95-100%) and NSAIDs ○ Other risk factors: Steroids, tobacco, alcohol, coffee, stress, bile reflux ○ Less common etiologies – Zollinger-Ellison syndrome – Hyperparathyroidism – Chronic renal failure – Chronic obstructive pulmonary disease ○ Pathogenesis – H. pylori mediates or facilitates damage to gastric and duodenal mucosa – gastric acid and gastric emptying acidic exposure in duodenum • Genetics ○ Genetic syndromes – Multiple endocrine neoplasia type 1 (MEN1) – Systemic mastocytosis ○ Greater concordance in monozygotic twins ○ Increased incidence with blood type O • Multiplicity ○ Ulcers located in duodenal bulb and beyond – Suggestive of Zollinger-Ellison syndrome

Gross Pathologic & Surgical Features • Round or oval, sharply punched-out and regular walls, flat adjacent mucosa

Microscopic Features • Necrotic debris, zone of active inflammation, granulation, and scar tissue

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic in some cases ○ Burning, gnawing, or aching pain at epigastrium 2-4 hours after meals – Relieved by antacids or food ○ Pain that awakens patients from sleep (66%) ○ Other signs/symptoms 320

– Pain episodes occurring in clusters of days/weeks followed by longer pain-free intervals – Rarely anorexia and weight loss □ Weight gain due to increased eating (for pain relief) • Lab data ○ Tests for H. pylori serology, urease breath test • Diagnosis: Endoscopy and biopsy

Demographics • Age ○ Adults • Gender ○ M=F • Epidemiology ○ Incidence: 200,000 cases per year ○ 2-3x more frequent than gastric ulcers

Natural History & Prognosis • Complications ○ Hemorrhage, perforation, obstruction, fistula ○ Giant duodenal ulcers have increased incidence of complications • Prognosis: Good with medical treatment or surgery

Treatment • Ulcer without H. pylori: H2-receptor antagonists (cimetidine, ranitidine, famotidine); proton-pump inhibitors (PPIs, e.g., omeprazole, lansoprazole) • Ulcer with H. pylori: H. pylori treatment and H2-receptor antagonists; proton-pump inhibitors ○ H. pylori treatment: Metronidazole, bismuth and clarithromycin, amoxicillin, tetracycline • Other agent: Sucralfate • Follow-up: Intractable ulcers and complications

DIAGNOSTIC CHECKLIST Consider • Eradication of H. pylori is 1st step of treatment ○ Coupled with "antacid" therapy (e.g., PPIs)

Image Interpretation Pearls • Check for duodenal bulb deformity • Prone compression views on upper GI necessary to evaluate anterior wall duodenal ulcers • CT with oral and IV contrast medium for suspected perforation

SELECTED REFERENCES 1.

2.

3.

Levenstein S et al: Psychological Stress Increases Risk for Peptic Ulcer, Regardless of Helicobacter pylori Infection or use of Non-steroidal Antiinflammatory Drugs. Clin Gastroenterol Hepatol. ePub, 2014 Schroder VT et al: Vagotomy/drainage is superior to local oversew in patients who require emergency surgery for bleeding peptic ulcers. Ann Surg. 259(6):1111-8, 2014 Khamaysi I et al: Acute upper gastrointestinal bleeding (UGIB) - initial evaluation and management. Best Pract Res Clin Gastroenterol. 27(5):633-8, 2013

Duodenal Ulcer Duodenum

(Left) Upper GI series in a 68year-old man with upper abdominal pain shows a contracted gastric antrum with an ulcer projecting off the lesser curve. Note the radiolucent ulcer collar at the base of the collection. The duodenal bulb is deformed and spastic, with folds radiating to a persistent collection on the anterior wall, representing an ulcer. (Right) Upper GI series in the same patient shows the gastric ulcer projecting off the lesser curve and the ulcer collar at the collection base.

(Left) Axial CECT through the upper abdomen in a 24-yearold man presenting with acute and chronic upper abdominal pain demonstrates free intraperitoneal gas . (Right) Axial CECT in the same patient shows the thickened appearance of the bulbar and post-bulbar duodenum and infiltration of the fat planes , findings that are characteristic of duodenal ulcer perforation.

(Left) Axial CECT in a 75-yearold man with abdominal pain and vomiting shows a distended stomach , inflammatory changes surrounding the 2nd portion of the duodenum and head of the pancreas, and extraluminal gas , indicating a perforated duodenal ulcer. (Right) Axial CECT in another patient shows a cluster of gas bubbles surrounding retroperitoneal portions of the duodenum and extending into the perirenal space via the renal hilum. A perforated duodenal ulcer was confirmed at surgery.

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Duodenum

Brunner Gland Hyperplasia KEY FACTS

TERMINOLOGY • Nonneoplastic hyperplasia of duodenal submucosal glands

IMAGING • Best imaging tools ○ Upper GI barium study and endoscopic US • Diffuse type (Brunner gland hyperplasia) ○ Multiple, small, submucosal nodules < 5 mm in proximal duodenum ○ "Cobblestone" or "strawberry" appearance • Solitary type (Brunner gland hamartoma) ○ Solitary, sessile, or pedunculate lesion > 5 mm in proximal duodenum • Submucosal heterogeneous and hypoechoic lesion on endoscopic US

TOP DIFFERENTIAL DIAGNOSES • Duodenitis ○ Diffuse, inflammatory changes are seen

(Left) Spot film from an upper GI series shows multiple small submucosal filling defects in the duodenal bulb, characteristic of Brunner gland hyperplasia. (Right) Spot film from an upper GI series shows the duodenal bulb with a "strawberry" appearance due to innumerable small, submucosal nodules of hyperplastic Brunner glands.

(Left) Spot film from an upper GI shows multiple small polypoid masses in the proximal duodenum. An endoscopic biopsy revealed hyperplasia and elements of hamartoma arising from Brunner glands. (Right) Spot film from an upper GI demonstrates a polypoid mass within the duodenal bulb. An endoscopic biopsy and resection revealed a hamartoma of a Brunner gland. Larger, isolated lesions, as in this case, are indistinguishable from many other duodenal masses and require a biopsy.

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• Duodenal flexure pseudotumor ○ Redundant mucosa can simulate luminal mass • Hamartomatous polyposis (Peutz-Jeghers) ○ Associated lesions (mucocutaneous pigmentation, etc.) • Familial polyposis syndrome ○ Associated extraintestinal manifestations (epidermoid cyst, lipoma, fibroma, desmoid tumors, etc.) • Duodenal metastases and lymphoma ○ Metastases: "Target" or bull's-eye lesion with rounded submucosal mass; ulceration is common

CLINICAL ISSUES • Epigastric pain is most common symptom • No treatment needed for diffuse type • Endoscopic or surgical resection for large hamartoma to verify histology

Brunner Gland Hyperplasia

Synonyms • Brunner gland hamartoma, Brunner gland adenoma (misnomer)

Definitions • Nonneoplastic hyperplasia of duodenal submucosal glands ○ Diffuse type (Brunner gland hyperplasia) – Multiple, small, submucosal nodules < 5 mm ○ Solitary type (Brunner gland hamartoma) – Solitary, sessile or pedunculated lesion > 5 mm

IMAGING

• Associated lesions (mucocutaneous pigmentation, etc.)

Familial Polyposis • Innumerable adenomatous colonic polyps (less common in stomach, small bowel, and duodenum) • Associated extraintestinal manifestations (epidermoid cyst, lipoma, fibroma, desmoid tumors, etc.)

Duodenal Metastases and Lymphoma • Metastases: "Target" or bull's-eye lesion with rounded submucosal mass; ulceration is common • Lymphoma: Bulky, hypovascular, soft tissue mass infiltrating submucosa of stomach and duodenum on CECT

PATHOLOGY

General Features

General Features

• Best diagnostic clue ○ "Strawberry" or "cobblestone" appearance in proximal duodenum on barium study • Location ○ Diffuse type: Most commonly in 1st part of duodenum (bulb) proximal to ampulla ○ Hamartoma: Most commonly in 1st and 2nd parts of duodenum • Morphology ○ Diffuse type: Solitary or multiple, small, rounded, submucosal nodules ○ Hamartoma: Solitary, polypoid, may have pedicle

• Etiology ○ Acid hypersecretion (no causal relationship has been proven) ○ Brunner glands secrete alkaline, bicarbonate-rich fluid to buffer gastric acid

Imaging Recommendations • Best imaging tool ○ Upper GI barium study ○ Endoscopic ultrasound

Fluoroscopic Findings • Diffuse type ○ Multiple, small, rounded nodules in proximal duodenum ○ "Cobblestone" or "strawberry" appearance • Brunner gland hamartoma ○ 1 smooth polypoid lesions ○ May be sessile or pedunculated

Ultrasonographic Findings • Submucosal heterogeneous and hypoechoic lesion on endoscopic US

CT Findings • Heterogeneous, slightly enhancing, polypoid lesion

DIFFERENTIAL DIAGNOSIS Duodenitis • Diffuse, inflammatory changes are seen • Erosions, thickened folds

Duodenal Flexure Pseudotumor • Acute angulation of lumen at apex of duodenal bulb • Redundant mucosa can simulate luminal mass

Hamartomatous Polyposis

Duodenum

TERMINOLOGY

Microscopic Features • Diffuse type: Prominent Brunner glands separated by fibrous septa • Hamartoma: Mixture of acini, ducts, smooth muscle, adipose tissue, and lymphoid tissue ○ Considerable histological overlap between 2 types ○ Better differentiated based on morphology and size

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Epigastric pain • Other signs/symptoms ○ Upper GI bleeding, upper GI obstruction, intussusception (all rare)

Demographics • Age ○ Any age, commonly 40-60 years • Epidemiology ○ Constitute 5-10% of duodenal masses

Treatment • No treatment needed for diffuse type • Endoscopic or surgical resection for large hamartoma to verify histology

SELECTED REFERENCES 1. 2. 3. 4.

Chen KM et al: A duodenal tumor with intermittent obstruction. Brunner's gland hyperplasia. Gastroenterology. 146(4):e7-8, 2014 Kim K et al: Clinicopathologic characteristics and mucin expression in Brunner's gland proliferating lesions. Dig Dis Sci. 58(1):194-201, 2013 Kini JR et al: Brunner's gland hamartoma and hyperplasia. Trop Gastroenterol. 31(2):121-3, 2010 Patel ND et al: Brunner's gland hyperplasia and hamartoma: imaging features with clinicopathologic correlation. AJR Am J Roentgenol. 187(3):715-22, 2006

• Peutz-Jeghers syndrome • Cluster of small polyps in ileum and jejunum (less common in duodenum, large bowel, and stomach) 323

Duodenum

SMA Syndrome KEY FACTS

TERMINOLOGY

PATHOLOGY

• Vascular compression of 3rd portion of duodenum between aorta and superior mesenteric artery (SMA)

• Predisposing conditions ○ Weight loss depletion of retroperitoneal fat , leading to narrowed aorto-mesenteric angle ○ Anatomical and congenital anomalies ○ Postoperative states (e.g., scoliosis)

IMAGING • Dilated 1st and 2nd portions of duodenum with abrupt straight line transition to collapsed duodenum as it crosses spine • Best imaging: Barium upper GI series and CECT • Aorto-SMA angle < 22-25° in sagittal plane ○ Reformat in sagittal plane to see aorta and SMA • Antiperistaltic flow of barium proximal to obstruction • Relief of obstruction in prone, knee-chest, or left lateral decubitus positions

TOP DIFFERENTIAL DIAGNOSES • Duodenal obstruction (other causes) • Intestinal scleroderma • Duodenal stricture

(Left) Supine film from an upper GI series in a woman with recent weight loss and early satiety shows an abrupt, straight-line cut-off of the 3rd portion of duodenum as it crosses over the midline, with dilation and slow emptying of the proximal duodenum. There is also a duodenal diverticulum . (Right) Axial CECT shows marked distention of the 2nd portion of the duodenum and stomach. The 3rd portion of the duodenum is compressed as it passes between the aorta and the superior mesenteric artery (SMA) .

(Left) Coronal reformatted CT in the same case shows dilation of the second portion of duodenum , while the remaining bowel is collapsed. Note this patient's thin body habitus. (Right) Sagittalreformatted CT in the same case shows a very narrow angle between the superior mesenteric artery and the aorta, with compression of the 3rd portion of duodenum as it passes between these vessels.

324

CLINICAL ISSUES • Postprandial epigastric pain, nausea, vomiting ○ Pain relieved in prone, knee-chest, or left lateral decubitus position • Surgery (bypassing duodenum) indicated when conservative therapy fails

DIAGNOSTIC CHECKLIST • Can be mimicked by or made worse by other causes of duodenal dilation (e.g., scleroderma)

SMA Syndrome

Definitions • Vascular compression of 3rd portion of duodenum between aorta and superior mesenteric artery (SMA)

IMAGING General Features • Best diagnostic clue ○ Dilated 1st and 2nd portions of duodenum with abrupt, straight-line transition to collapsed duodenum as it crosses spine

Imaging Recommendations • Best imaging tool ○ Barium upper GI series with CECT • Protocol advice ○ Obtain thin slice CECT with good contrast bolus – Reformat in sagittal plane to see aorta and SMA

Fluoroscopic Findings • Dilatation of 1st and 2nd portions of duodenum ± gastric dilatation • Abrupt narrowing of 3rd portion of duodenum ○ Vertical, linear, extrinsic, band-like defect overlying spine • Antiperistaltic flow of barium proximal to obstruction • Relief of obstruction in prone, knee-chest, or left lateral decubitus positions

CT Findings • CECT ○ Beak-like compression of 3rd part of duodenum between SMA and aorta ○ Aorto-SMA angle < 22-25° in sagittal plane ○ Aorto-SMA distance < 8 mm

DIFFERENTIAL DIAGNOSIS Duodenal Obstruction (Other Causes) • Gastroduodenoscopy is needed to rule out intraluminal causes • Other causes of duodenal obstruction (e.g., cancer) can mimic or exacerbate SMA syndrome

Intestinal Scleroderma • Dilated atonic small bowel with crowded folds and widemouthed sacculations • Check for other small bowel, lung, or skin changes of scleroderma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Postprandial epigastric pain, nausea, vomiting ○ Pain relieved in prone, knee-chest, or left lateral decubitus position • Other signs/symptoms ○ Anorexia, weight loss

Demographics • Gender ○ More common in women

Natural History & Prognosis • Good response to medical and surgical treatments

Treatment • Acute symptoms ○ NG tube decompression of stomach • Medical treatment ○ Increase body weight by tube feeding or parenteral nutrition • Surgery ○ Indicated when conservative therapy fails ○ Gastrojejunostomy, duodenojejunostomy

DIAGNOSTIC CHECKLIST

Duodenal Stricture

Consider

• Usually postinflammatory with prior history of ulcer disease • More common in proximal duodenum

• Can be mimicked by or made worse by other causes of duodenal dilation

PATHOLOGY General Features • Etiology ○ Impingement of 3rd duodenum by aorta and SMA • Predisposing conditions ○ Weight loss depletion of retroperitoneal fat leads to narrowed aorto-mesenteric angle

Duodenum

– Chronic wasting diseases □ Cancer, paraplegia, cardiac cachexia, drug abuse, body casts – Anorexia nervosa, malabsorption – Catabolic states □ Burn, trauma ○ Anatomical/congenital anomalies – High insertion of ligament of Treitz cephalad dislocation of duodenum – Intestinal malrotation – Low origin of SMA decreased aorto-mesenteric distance – Lumbar lordosis ○ Postoperative states – Scoliosis surgery – Bariatric surgery – Nissen fundoplication – Aortic aneurysm repair – Ileoanal pouch anastomosis mesenteric tension caudal pull of SMA aorto-mesenteric angle

TERMINOLOGY

SELECTED REFERENCES 1.

Lam DJ et al: Superior mesenteric artery syndrome following surgery for adolescent idiopathic scoliosis: a case series, review of the literature, and an algorithm for management. J Pediatr Orthop B. 23(4):312-8, 2014

325

Duodenum

Gastroduodenal Trauma KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Trauma to duodenum resulting in intramural hematoma or laceration

• Clinical profile ○ Child with midepigastric blunt trauma, adult with highspeed motor vehicle crash injuries ○ Other forms of blunt trauma (e.g., assault, sports injuries) ○ Iatrogenic injuries include endoscopy, especially with endoscopic sphincterotomy/papillotomy and stone removal from common duct • Most common signs/symptoms ○ Nausea, vomiting, abdominal pain/tenderness • Treatment ○ Nonoperative management for isolated hematoma without perforation ○ Surgery for duodenal perforation and head of pancreas injury (pancreaticoduodenal resection;modified Whipple)

IMAGING • Best diagnostic clue ○ High-density intramural hematoma, pneumoperitoneum, anterior pararenal space fluid/air • Upper GI findings ○ Duodenal lumen narrowing by hematoma; contrast extravasation (peritoneal cavity, retroperitoneum) • Best imaging tool: CECT, upper GI

TOP DIFFERENTIAL DIAGNOSES • Perforated duodenal ulcer • Villous adenoma • Duodenal lymphoma

DIAGNOSTIC CHECKLIST • Consider perforated duodenal ulcer • Clinical features are usually distinctive

(Left) Axial CECT in a 16-yearold boy with blunt abdominal trauma shows a highattenuation mass within the duodenal wall (hematoma) that narrows the duodenal lumen. (Right) Another CT section in the same case shows the intramural hematoma extending into and narrowing the lumen of the 3rd portion of duodenum. This resulted in partial gastric outlet obstruction but resolved over the next 10 days with nonoperative management.

(Left) CT in a 25-year-old man had blunt trauma shows extensive fluid &/or infiltration of the anterior pararenal and perirenal spaces. Signs of pancreatic injury include indistinct appearance of the pancreatic head, a thin fracture plane through the neck , and fluid between the pancreas and the splenic vein . (Right) Another CT section in the same patient shows gas bubbles adjacent to the duodenum indicating duodenal perforation (confirmed at surgery) along with pancreatic transection.

326

Gastroduodenal Trauma

PATHOLOGY

Definitions

General Features

• Trauma to duodenum resulting in intramural hematoma or laceration

• Etiology ○ Blunt trauma accounts for most cases ○ Iatrogenic (e.g., perforation of duodenum from ERCP, especially with endoscopic sphincterotomy/papillotomy and stone extraction) • Associated abnormalities ○ Pancreatic laceration/fracture (47%), liver or splenic laceration

IMAGING General Features • Best diagnostic clue ○ CT: High-density intramural hematoma, pneumoperitoneum – Anterior pararenal space fluid or gas

Radiographic Findings • Radiography ○ Pneumoperitoneum, extraluminal retroperitoneal gas

Fluoroscopic Findings • Upper GI ○ Duodenal lumen narrowing by hematoma – Oral contrast extravasation

CT Findings • NECT ○ High-density intramural hematoma • CECT ○ Nonenhancing intramural hematoma ○ Extraluminal gas &/or fluid/oral contrast ○ Active extravasation from gastroduodenal artery ○ Interruption of duodenal wall ○ Periduodenal stranding

MR Findings • T1WI ○ High signal intramural hematoma • T2WI ○ High signal free fluid &/or hematoma • T1WI C+ ○ Thick duodenal wall, nonenhancing hematoma

Ultrasonographic Findings • Echogenic intramural mass representing hematoma

Angiographic Findings • Bleeding from gastroduodenal artery or branch

Staging, Grading, & Classification • Isolated intramural hematoma • Perforated duodenum • Head of pancreas and duodenal injury

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Nausea, vomiting, abdominal pain/tenderness • Clinical profile ○ Child with midepigastric blunt trauma, adult with highspeed motor vehicle crash injuries ○ Recent upper endoscopy patient

Demographics • Epidemiology ○ 4th most common organ injury in children, 2-10% of all blunt injuries

Natural History & Prognosis • Isolated hematoma: Excellent prognosis with nonoperative management • Combined duodenal perforation with head of pancreas laceration: Mortality = 26%

Treatment • Options, risks, complications ○ Nonoperative management for isolated hematoma without perforation ○ Surgery for duodenal perforation and head of pancreas injury

DIAGNOSTIC CHECKLIST

Imaging Recommendations

Consider

• Best imaging tool ○ CECT, upper GI

• Perforated duodenal ulcer can have similar imaging findings, but clinical setting differs

DIFFERENTIAL DIAGNOSIS Perforated Duodenal Ulcer • Pneumoperitoneum, anterior pararenal space fluid/air • Periduodenal inflammatory changes • Mural thickening of duodenum

Image Interpretation Pearls • Ectopic gas/fluid in pararenal space

SELECTED REFERENCES 1.

Villous Adenoma

2.

• Polypoid mucosal mass (3-9 cm)

3.

Duodenal Lymphoma

4.

• Bulky submucosal mass

Duodenum

TERMINOLOGY

Cho HS et al: Multidetector CT findings of bowel transection in blunt abdominal trauma. Korean J Radiol. 14(4):607-15, 2013 Singh S et al: Blunt duodenal trauma. J Coll Physicians Surg Pak. 23(5):350-2, 2013 Thompson CM et al: Revisiting the pancreaticoduodenectomy for trauma: a single institution's experience. J Trauma Acute Care Surg. 75(2):225-8, 2013 LeBedis CA et al: CT imaging of blunt traumatic bowel and mesenteric injuries. Radiol Clin North Am. 50(1):123-36, 2012

327

Duodenum

Aortoenteric Fistula KEY FACTS

TERMINOLOGY

PATHOLOGY

• Abnormal communication between aorta and gastrointestinal tract

• Primary etiology: Abdominal aortic aneurysms, infectious aortitis, penetrating peptic ulcer, tumor invasion, radiation therapy • Secondary etiology: Most common type, following aortic reconstructive surgery

IMAGING • Best diagnostic clue: Inflammatory stranding and gas between abdominal aorta and 3rd part of duodenum following aneurysm repair • Location: Duodenum (80%); jejunum and ileum (10-15%); stomach and colon (5%) • Best imaging tool: CT 94% sensitive; 85% specific

TOP DIFFERENTIAL DIAGNOSES • • • •

Periaortitis Retroperitoneal fibrosis Postoperative changes Postendovascular stent

(Left) Graphic shows a fistula between the transverse duodenum and aorta at the site of the graft-aortic suture line . (Right) Axial CECT in a 70-year-old man presenting with fever and hematemesis months after abdominal aortic aneurysm (AAA) repair shows the native, calcified aortic wall wrapped around a synthetic graft. A gas collection is noted between the graft and aortic wall , indicating infection or fistula. Note the soft tissue density surrounding the aorta and 3rd portion of duodenum .

(Left) This elderly woman had pain and fever years after AAA repair. Axial CECT shows a calcified aortic wall wrapped around synthetic graft material . At the level of the 3rd portion of the duodenum, the duodenal wall appears to be adherent to the aorta. Note an enhanced focus that may represent active bleeding or inflammation. (Right) Axial CECT in the same patient reveals several bubbles of extraluminal gas ; aortoenteric fistula with underlying infection was surgically confirmed.

328

CLINICAL ISSUES • "Herald" GI bleeding, followed hours, days, or weeks later by catastrophic hemorrhage • Percutaneous drainage of infected perigraft fluid may be initial treatment, followed by surgery • Very poor prognosis, up to 85% mortality

DIAGNOSTIC CHECKLIST • Perigraft infection evidenced by ectopic gas or perigraft soft tissue raises suspicion of fistula

Aortoenteric Fistula

PATHOLOGY

Definitions

General Features

• Abnormal communication between aorta and gastrointestinal (GI) tract

• Etiology ○ Primary: Abdominal aortic aneurysms, infectious aortitis, penetrating peptic ulcer, tumor invasion, radiation therapy ○ Secondary: Most common type, usually following aortic reconstructive surgery – Can occur after "open"/endovascular aneurysm repair ○ Pathogenesis – 3rd portion of duodenum fixed and apposed to anterior wall of aortic aneurysm pressure necrosis – Surgery blood supply compromised – Pseudoaneurysm formation with erosion – Graft and suture line infection anastomotic breakdown – Aortocolonic fistula may follow aortoiliac graft □ Sigmoid diverticulitis near graft site may lead to fistula from colon to iliac artery/graft • Associated abnormalities ○ Aortic aneurysm or atherosclerosis; perigraft infection

IMAGING General Features • Best diagnostic clue ○ Inflammatory stranding and gas between abdominal aorta and 3rd part of duodenum following aneurysm repair • Location ○ Duodenum (80%); jejunum and ileum (10-15%); stomach and colon (5%)

CT Findings • Microbubbles adjacent to aortic graft • Focal bowel wall thickening &/or perigraft soft tissue thickening > 5 mm • Pseudoaneurysm, disruption of aneurysmal wrap • Contrast in pseudoaneurysm on arterial phase • Arterial phase: attenuation of intestinal lumen contents ○ Attenuation of intestinal contents may decrease on delayed phase through same region ○ Volume of intestinal blood may increase on delayed phase • CT-guided needle aspiration: May confirm perigraft infection

Nuclear Medicine Findings • PET/CT ○ Site of infection/fistula is usually FDG-avid on PET • Tagged RBC study ○ Radiolabelled RBC accumulate within bowel at site of fistula • Tagged WBC scan can confirm infection

Imaging Recommendations • Best imaging tool ○ CT: 94% sensitive; 85% specific ○ PET/CT may be even better – CT portion of exam should be of diagnostic quality with IV contrast administration

DIFFERENTIAL DIAGNOSIS Periaortitis • Inflammatory perianeurysmal fibrosis • Soft tissue attenuation encases aorta, IVC

Retroperitoneal Fibrosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ "Herald" GI bleeding, followed hours, days, or weeks later by catastrophic hemorrhage ○ Abdominal/back pain, palpable and pulsatile mass ○ Intermittent rectal bleeding and recurrent anemia ○ Low-grade fever, fatigue, weight loss, leukocytosis

Demographics • Age ○ 55 and older • Gender ○ M:F = 4-5:1 • Epidemiology ○ Incidence: 0.6-1.5% after aortic surgery ○ Onset after surgery: 21 days to 14 years

Natural History & Prognosis • Very poor prognosis, up to 85% mortality

Treatment • Percutaneous drainage of infected perigraft fluid may be initial treatment, followed by surgery • Emergent reconstructive surgery may be required; removal of infected graft is usually required

DIAGNOSTIC CHECKLIST

• Mantle of soft tissue enveloping aorta, IVC, ureters

Image Interpretation Pearls

Postoperative Changes

• Perigraft infection evidenced by ectopic gas or perigraft soft tissue raises suspicion of fistula

• Perigraft fluid may persist for up to 3 months

Postendovascular Stent • Endoleak: Blood flow outside stent but within aneurysm sac or adjacent vascular segment • Gas bubbles between stent-graft and aortic wall

Duodenum

TERMINOLOGY

SELECTED REFERENCES 1.

Capoccia L et al: Current technology for the treatment of infection following abdominal aortic aneurysm (AAA) fixation by endovascular repair (EVAR). J Cardiovasc Surg (Torino). 55(3):381-9, 2014

329

Duodenum

Duodenal Polyps KEY FACTS

IMAGING • Duodenal polyps are much less common than gastric • Epithelial polyps (mucosal lesions) classification • Adenomatous polyps (most common) ○ Single, lobulated or cauliflower-like surface • Hyperplastic polyps ○ Multiple, small, sessile polyps of uniform size • Hamartomas: Cluster of broad-based polyps ○ Can occur as part of Peutz-Jeghers syndrome ○ More common are hamartomas or hyperplasia of Brunner glands • Submucosal (intramural) lesions • Duodenal GI stromal tumor (GIST) ○ Soft tissue density mass that deforms lumen ○ Lesions 2 cm often have central necrosis • Duodenal lipoma ○ Characteristic fat density on CT • Other mesenchymal tumors (rare)

(Left) Spot film from upper GI series shows a large adenomatous polyp as a radiolucent filling defect within the duodenum. (Right) Spot film from an upper GI series demonstrates a polypoid mass within the duodenal bulb. Endoscopic biopsy and resection revealed a hamartoma of the Brunner gland. Brunner gland hamartomas (hyperplasia) are usually multiple, smaller lesions. Larger, isolated lesions, as in this case, are indistinguishable from many other duodenal masses and require biopsy.

(Left) Axial CECT in a middleaged man with vague abdominal pain shows a subtle heterogeneous mass within the lumen of the 2nd part of the duodenum without signs of luminal obstruction. There was also no biliary or pancreatic ductal obstruction. (Right) Gross pathology in the same case shows the mass previously identified on CT. After endoscopic confirmation of a villous tumor at this location, a pancreaticoduodenectomy (Whipple procedure) was performed.

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• Carcinoid tumor ○ Single or multiple; may ulcerate

"target" lesions

TOP DIFFERENTIAL DIAGNOSES • • • • • • • •

Brunner gland hyperplasia Duodenal flexure pseudotumor Ectopic gastric mucosa Duodenal carcinoma Intestinal metastases and lymphoma Duodenal hematoma Kaposi sarcoma Ampullary carcinoma

DIAGNOSTIC CHECKLIST • Check for family history of GI tract polyps ○ e.g., familial polyposis or Peutz-Jeghers • Lipomas can be diagnosed with confidence on CT • Most other polyps have nonspecific imaging features

Duodenal Polyps

Definitions • Protruding, space-occupying masses within duodenum

IMAGING General Features • Best diagnostic clue ○ Radiolucent filling defects, ring shadows, or contour defect on barium study ○ CT signs of intraluminal &/or intramural mass • Size ○ Adenomatous and hamartomatous polyps: Several mm to 2 cm • Morphology ○ Epithelial polyps (mucosal lesions) ○ Adenomatous polyps (most common) – Usually single, lobulated or cauliflower-like surface – More evident on upper GI series than on CT ○ Hyperplastic polyps: Smooth, sessile, pedunculated – Much less common in duodenum than in stomach ○ Hamartomas: Cluster of broad-based polyps – Can occur as part of Peutz-Jeghers syndrome – More common are hamartomas or hyperplasia of Brunner glands • General features ○ Duodenal polyps are much less common than gastric polyps ○ Polyps are classified into 3 types based on predominant glandular architecture – Adenomatous – Hyperplastic – Hamartomatous ○ Adenomatous polyps – Most common polyps of duodenum – Usually solitary □ Unless part of polyposis syndrome – Typically arise from medial wall of bulb or 2nd part of duodenum – Increased risk of malignant change via adenomacarcinoma sequence □ Composed of dysplastic epithelium – Depending on predominant glandular architecture, classified as □ Tubular (75%), tubulovillous (15%), or villous (10%) – Duodenum: 2nd most common site of familial adenomatous polyposis (FAP) after colon □ Occur in 47-72% of familial polyposis cases □ FAP cases: Multiple sessile ± pedunculated polyps □ Clustered around periampullary region □ Also likely to have similar lesions in stomach □ 4% of patients develop periampullary carcinoma < 5 years after colectomy ○ Hyperplastic polyps – Rare, benign epithelial neoplasms of duodenum – Multiple, small sessile polyps of uniform size on upper GI series – Virtually no malignant potential ○ Hamartomatous polyps

– Usually seen in Peutz-Jeghers syndrome (PJS) □ Multiple polyps from a few mm to 2 cm in duodenum, small bowel, ± stomach – Duodenum most common after jejunum/ileum – Brunner gland hyperplasia may lead to large lesion called hamartoma ○ Submucosal (intramural) lesions – Duodenal GI stromal tumor (GIST) □ Duodenum is 2nd most common site (after stomach) for GIST □ Usually benign, but complete resection is necessary □ Size: Several mm to many centimeters □ Most of lesion is exophytic □ Soft tissue density mass that deforms lumen of duodenum □ Mucosa remains intact unless ulcerated □ Ulcerated lesions may have bull's-eye appearance on upper GI series □ Lesions 2 cm often have central necrosis evident on CECT □ May have small foci of calcification – Duodenal lipoma □ Appears soft on upper GI series (changeable and compressible) □ Originates within submucosa but peristalsis usually pulls lesion into lumen as polypoid mass □ Characteristic fat density on CT allows easy diagnosis and obviates additional evaluation or surgery – Other mesenchymal tumors □ Rare; may originate from any component (neural, vessels [hemangioma, lymphangioma], etc.) □ Usually have nonspecific appearance on upper GI series and CT – Carcinoid tumor □ Single or multiple □ Submucosal in origin □ Usually has intact mucosa □ May ulcerate "target" or bull's-eye lesion(s) □ Usually benign; rarely carcinoid syndrome □ May be associated with neurofibromatosis or Zollinger-Ellison syndrome

Duodenum

TERMINOLOGY

Imaging Recommendations • Fluoroscopic-guided double contrast barium upper GI ○ En face, profile, and oblique views • CECT ○ Multiplanar reformations allow better recognition of morphology and relationship to lumen, wall, adjacent structures

DIFFERENTIAL DIAGNOSIS Brunner Gland Hyperplasia • Multiple small, rounded nodules in duodenal bulb ("cobblestone," "Swiss cheese," or "strawberry" appearance) • Brunner gland hamartomas ○ Submucosal or sessile lesions mimicking polyps ○ May also appear as large polypoid lesions 331

Duodenum

Duodenal Polyps

Duodenal Flexure Pseudotumor • Changeable filling defect due to redundant, normal duodenal mucosa • Due to acute bend of duodenal lumen between bulb and 2nd portion

Ectopic Gastric Mucosa • Discrete, angulated, or polygonal 1-5 mm nodules (filling defects) near base of duodenal bulb

Duodenal Carcinoma • • • •

Usually obstructing, concentric mass Fixed narrowing of lumen May invade adjacent tissues ± nodal or liver metastases

Intestinal Metastases and Lymphoma • Lymphoma tends to be large, soft mass without luminal obstruction ○ Rare in duodenum per se – Duodenum may be indented by upper abdominal lymphomatous nodes • Metastases to duodenum are uncommon ○ Melanoma, breast, and lung are among most common primaries

Duodenal Hematoma • • • • •

Submucosal mass in 2nd or 3rd portion More common in children Spiky folds on upper GI High-attenuation mass on CT History of trauma or anticoagulation is key

Kaposi Sarcoma • Usually multiple submucosal masses • ± cavitation ("target" or bull's-eye lesions) • Occurs in immunocompromised patients, especially gay men with AIDS

Ampullary Carcinoma • Mass arising from ampulla or pancreatic head may present as intraluminal duodenal mass • Obstruction of common bile and pancreatic ducts • May be indistinguishable from duodenal carcinoma by imaging • Endoscopy allows definitive diagnosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic, low-grade upper GI bleeding, obstructive jaundice

Demographics • Age ○ FAP and PJS: 10-30 years • Epidemiology ○ < 1% of all GI tract polyps

Natural History & Prognosis • Complications: Risk of cancer in adenomatous polyps • Prognosis: Benign (good); invasive carcinoma (poor)

Treatment • Small (< 1 cm) and asymptomatic: Periodic surveillance • Large (> 1 cm), lobulated, and symptomatic: Polypectomy ○ Lipomas can be diagnosed with confidence and ignored

DIAGNOSTIC CHECKLIST Consider • Check for family history of GI tract polyps • Screen all of GI tract to rule out polyposis syndromes

Image Interpretation Pearls • Lobulated polyp and basal indentation ○ Raises concern for malignancy

SELECTED REFERENCES 1.

2.

3. 4. 5.

6.

7.

PATHOLOGY General Features

8.

• Etiology ○ Varies by type of polyp • Genetics ○ FAP: Abnormal APC gene on chromosome 5q ○ PJS: Spontaneous gene mutation on chromosome 19 • Associated abnormalities ○ Polyposis syndromes

9.

Gross Pathologic & Surgical Features • Adenomatous polyps: Sessile or pedunculated

Microscopic Features • Adenomatous: Tubular, tubulovillous, villous pattern 332

10.

11. 12. 13.

Wood LD et al: Upper GI tract lesions in familial adenomatous polyposis (FAP): enrichment of pyloric gland adenomas and other gastric and duodenal neoplasms. Am J Surg Pathol. 38(3):389-93, 2014 Tan CL et al: Muco-submucosal elongated polyps of the gastrointestinal tract: a case series and a review of the literature. World J Gastroenterol. 19(11):1845-9, 2013 Palanivelu C et al: Laparoscopic antrectomy for a proximal duodenal Brunner gland hamartoma. JSLS. 13(1):110-5, 2009 Velasco S et al: Scanographic features of gastrointestinal stromal tumors. Gastroenterol Clin Biol. 32(12):1001-13, 2008 Baichi MM et al: Small-bowel masses found and missed on capsule endoscopy for obscure bleeding. Scand J Gastroenterol. 42(9):1127-32, 2007 Iusco D et al: Brunner's gland hamartoma: 'over-treatment' of a voluminous mass simulating a malignancy of the pancreatic-duodenal area. JOP. 6(4):348-53, 2005 Jiang LL et al: [Hemangioma and vascular malformation of small intestine: a clinicopathologic analysis of fifty-one cases.] Zhonghua Bing Li Xue Za Zhi. 34(5):275-8, 2005 Levy AD et al: Duodenal carcinoids: imaging features with clinical-pathologic comparison. Radiology. 237(3):967-72, 2005 Piscitelli D et al: [Unusual presentation of metastatic osteosarcoma as a giant duodenal polyp. A case report.] Pathologica. 97(2):88-91, 2005 Tanţău M et al: Gastrointestinal lymphomatous polyposis--clinical, endoscopical and evolution features. A case report. Rom J Gastroenterol. 14(3):273-8, 2005 Waye JD et al: Approach to benign duodenal polyps. Gastrointest Endosc. 55(7):962-3, 2002 Buetow PC et al: Duodenal gangliocytic paraganglioma: CT, MR imaging, and US findings. Radiology. 204(3):745-7, 1997 Harned RK et al: Extracolonic manifestations of the familial adenomatous polyposis syndromes. AJR Am J Roentgenol. 156(3):481-5, 1991

Duodenal Polyps Duodenum

(Left) Spot films from an upper GI series show a long polypoid filling defect within the lumen of the duodenum. Surgical resection confirmed a benign adenomatous polyp. (Right) Spot film from an upper GI series in a patient with familial polyposis shows multiple polyps of varying size within the distal stomach and duodenum . A large, lobulated polyp is present near the ampulla, raising concern for an ampullary adenoma or carcinoma, which is common in patients with familial polyposis.

(Left) Spot film from an upper GI series in an elderly woman shows a smooth, oval filling defect within the lumen of the 3rd portion of the duodenum. Endoscopy confirmed a duodenal lipoma. (Right) Axial CECT shows a duodenal lipoma diagnosed as an incidental finding. The fat density of the mass is diagnostic of a lipoma. The mass appears to be intraluminal, due to the effects of chronic peristaltic tugging, causing it to elongate into an intraluminal polypoid shape.

(Left) Axial CT in an 81-yearold man shows a large mass arising from the duodenum, with foci of necrosis and calcification . These findings are typical for GI stromal tumor (GIST). (Right) Additional axial CECT section in the same patient shows more necrosis within the large mass. The duodenum is 2nd to the stomach as a common site for these tumors.

333

Duodenum

Duodenal Carcinoma KEY FACTS

IMAGING

• Annular pancreas

• Irregular intraluminal mass or "apple core" lesion at or distal to ampulla of Vater • Irregular thickening of duodenal wall • Concentric narrowing of duodenal lumen • Polypoid intraluminal mass • Local lymphadenopathy and local infiltration • Biliary ± pancreatic duct dilatation ○ With periampullary tumors • Liver ± peritoneal metastases

PATHOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • • • • •

Pancreatic ductal carcinoma Ampullary carcinoma Intestinal metastases and lymphoma GI stromal tumor (GIST) Duodenal ulcer Crohn disease Tuberculosis

(Left) Axial CECT in a 60-yearold man with weight loss and early satiety shows obvious liver metastases . (Right) Axial CECT in the same patient also shows paraduodenal lymph node metastases .

(Left) Axial CECT in the same patient shows the relatively subtle mass that narrows the 3rd portion of the duodenum . There is also a subtle extension of tumor along the superior mesenteric vessels . (Right) Film from an upper GI series in the same patient shows the duodenal carcinoma more clearly. Note the "shoulder" or abrupt transition to tumor at its proximal extent. The lumen of the more proximal duodenum is dilated.

334

• Risk factors ○ Familial polyposis syndromes (especially Gardner) ○ Crohn disease ○ Cigarette smoking and alcohol abuse

CLINICAL ISSUES • Other signs/symptoms ○ Nausea and vomiting, weight loss, anemia, upper GI bleed ○ Periampullary tumors may present with jaundice • Rare: Represents < 1% of all gastrointestinal neoplasms

DIAGNOSTIC CHECKLIST • Most duodenal carcinomas cause focal stenoses or obstruction • A large mass with cavitation is more likely to be lymphoma or GIST

Duodenal Carcinoma

Abbreviations

○ Multiplanar MIP and volume-rendered CT images

DIFFERENTIAL DIAGNOSIS

• Duodenal carcinoma (CA)

Neoplasms

Synonyms

• Ampullary and periampullary adenocarcinomas ○ Pancreatic ductal carcinoma – Hypodense mass centered in pancreas with ductal obstruction ○ Ampullary carcinoma ○ Cholangiocarcinoma – Biliary obstruction with small mass • Intestinal metastases and lymphoma ○ Contiguous spread from pancreatic, colon, kidney, or gallbladder carcinoma ○ Hematogenous metastases from melanoma, Kaposi sarcoma, lung or breast cancer ○ Periduodenal lymph node metastases from other malignancies • Other duodenal primary neoplasms ○ Duodenal lymphoma – Bulky, usually does not obstruct ○ Malignant GI stromal tumor – Hypervascular mass, mostly exophytic ○ Duodenal carcinoid

• Duodenal adenocarcinoma

Definitions • Primary malignant neoplasm arising in duodenal mucosa

IMAGING General Features • Best diagnostic clue ○ Irregular intraluminal mass or "apple core" lesion at or distal to ampulla of Vater • Location ○ 15% in 1st portion of duodenum ○ 40% in 2nd portion of duodenum ○ 45% in distal duodenum • Size ○ Usually < 8 cm • Morphology ○ Polypoid, ulcerated, or annular constricting mass ○ Intraluminal mass with numerous frond-like projections for carcinomas arising in villous tumors

Fluoroscopic Findings • May have various appearances ○ Ulcerated mass ○ Polypoid mass ○ Annular constricting "apple core" lesion ○ "Soap bubble" reticulated pattern for villous tumors

CT Findings • CECT ○ Discrete mass or irregular thickening of duodenal wall ○ Concentric narrowing of duodenal lumen ○ Polypoid intraluminal mass ○ Local lymphadenopathy ○ Infiltration of adjacent fat ○ Biliary ± pancreatic duct dilatation – With periampullary tumors ○ Liver ± peritoneal metastases

Inflammatory • Duodenal ulcer ○ Spasm may narrow lumen • Zollinger-Ellison syndrome ○ Multiple post-bulbar ulcers, thickened folds, hypersecretion • Crohn disease ○ Usually with other sites of involvement in distal bowel

Infectious • Tuberculosis ○ May be indistinguishable from cancer on imaging

Congenital • Annular pancreas ○ CT findings are diagnostic (pancreatic tissue encircling 2nd duodenum) • Enteric duplication cyst ○ Encapsulated fluid collection; not soft tissue mass

MR Findings

Trauma

• MRCP ○ May see pancreatic or biliary ductal dilatation with periampullary duodenal carcinomas

• Gastroduodenal trauma ○ Duodenal hematoma is more common in children ○ Spiked folds and luminal narrowing

Ultrasonographic Findings • Grayscale ultrasound ○ Hypoechoic mass in duodenum with echogenic center: Pseudokidney sign • Color Doppler ○ May see invasion of adjacent vascular structures

Imaging Recommendations • Best imaging tool ○ Thin-section CECT with water for luminal distention and dual-phase arterial and venous imaging • Protocol advice

Duodenum

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ Adenoma-carcinoma sequence – Adenomatous polyps are most important risk factor ○ Risk factors – Familial polyposis syndromes (especially Gardner) – Crohn disease – Cigarette smoking – Alcoholism 335

Duodenum

Duodenal Carcinoma

• Genetics ○ Alterations in oncogenes ERBB2, KRAS, CCND1, and p53 • Adenocarcinomas represent 73-90% of malignant duodenal tumors • Small bowel adenocarcinomas are rare, especially in relation to length of small bowel ○ 45% of small bowel adenocarcinomas arise in duodenum ○ 25% of all malignant small bowel tumors occur in duodenum

Staging, Grading, & Classification • American Joint Committee on Cancer (AJCC) TNM staging system ○ Primary tumor (T) – T1: Tumor invades lamina propria or submucosa – T2: Tumor invades muscularis propria – T3: Tumor invades through muscularis propria and 2 cm into adjacent tissues – T4: Tumor perforates visceral peritoneum, directly invades other organs, or extends > 2 cm into adjacent tissues ○ Regional lymph nodes (N) – N0: No regional nodes involved – N1: Regional lymph node metastasis ○ Distant metastasis (M) – M0: No distant metastasis – M1: Distant metastasis ○ Staging – Stage I: T1 or T2, N0, M0 – Stage II: T3 or T4, N0, M0 – Stage III: Any T, N1, M0 – Stage IV: Any T, any N, M1

Gross Pathologic & Surgical Features • Duodenal mass may be flat, stenosing, ulcerative, infiltrating, or polypoid in growth pattern • Secondary cancers far more common than primary cancers in proximal small bowel ○ Often difficult to distinguish primary duodenal CA from secondary GI adenocarcinoma even with special stains • Proximal small bowel adenocarcinoma may be marker for familial or multicentric cancer syndrome

Microscopic Features • Similar histology to other GI adenocarcinomas ○ Cellular and nuclear pleomorphism ○ Dysplasia ○ Gland-in-gland appearance ○ Invasion into adjacent normal tissues • Most duodenal carcinomas are moderately differentiated with variable mucin production • 20% of duodenal carcinomas are poorly differentiated

• Clinical profile ○ Increased incidence of duodenal CA in familial polyposis syndromes – Peutz-Jeghers syndrome, Gardner syndrome

Demographics • Age ○ 7th decade – Median age: 60 years ○ Low incidence in patients under 30 • Gender ○ Slight male predominance • Epidemiology ○ Rare: Represents < 1% of all gastrointestinal neoplasms ○ Incidence rises with age

Natural History & Prognosis • Spreads by direct extension to adjacent organs and through serosa to peritoneal cavity • Metastasizes hematogenously to liver, lungs, and bone • Metastasizes via lymphatics to regional nodes • 22-71% of patients have positive nodes at presentation • Prognosis depends on resectability, lymph node involvement, and somewhat on histologic grade • Vascular invasion makes lesion unresectable

Treatment • Options, risks, complications ○ Surgery for resectable lesions – Pancreaticoduodenectomy for 1st and 2nd portion of duodenum lesions – Segmental duodenectomy and primary reanastomosis for 3rd and 4th portions of duodenum lesions ○ Unresectable tumors: Palliation with radiation, chemotherapy, stenting

DIAGNOSTIC CHECKLIST Consider • Check for vascular invasion, especially for lesions of 2nd and 3rd duodenum • Look for regional lymph nodes and liver metastases

Image Interpretation Pearls • Most duodenal carcinomas cause focal stenoses or obstruction; large mass with cavitation is more likely lymphoma or GIST • Scrutinize duodenum when periduodenal lymphadenopathy is present on CT without obvious source

SELECTED REFERENCES 1. 2.

CLINICAL ISSUES

336

Presentation

3.

• Most common signs/symptoms ○ Upper abdominal pain secondary to obstruction ○ Other signs/symptoms – Nausea and vomiting, weight loss, anemia, upper GI bleed – Periampullary tumors may present with jaundice

4.

Qureshi S et al: Malignant pyloro-duodenal obstruction: role of self expandable metallic stents. J Pak Med Assoc. 64(1):16-9, 2014 Wood LD et al: Upper GI tract lesions in familial adenomatous polyposis (FAP): enrichment of pyloric gland adenomas and other gastric and duodenal neoplasms. Am J Surg Pathol. 38(3):389-93, 2014 Struck A et al: Non-ampullary duodenal adenocarcinoma: factors important for relapse and survival. J Surg Oncol. 100(2):144-8, 2009 Lawler LP et al: Peripancreatic masses that simulate pancreatic disease: spectrum of disease and role of CT. Radiographics. 23(5):1117-31, 2003

Duodenal Carcinoma Duodenum

(Left) Axial CECT in a 49-yearold man with abdominal pain and abnormal liver function shows dilation of the intrahepatic bile ducts . (Right) Axial CECT in the same patient shows that the pancreatic duct is also dilated. The findings, to this point, suggest a malignant obstructing neoplasm at or near the ampulla of Vater.

(Left) Axial CECT in the same patient shows that the pancreatic head is normal, while the distal common bile duct remains dilated. (Right) Axial CECT in the same patient shows a large mass present within the lumen of the 2nd and 3rd portions of the duodenum that obstructed the ducts at the site of a relatively low-lying ampulla. Endoscopy confirmed a duodenal carcinoma arising in a villous adenoma.

(Left) Axial NECT in an 88year-old man with early satiety and weight loss showed gastric distention (not seen on this section). The lumen of the 2nd portion of duodenum is abruptly and eccentrically narrowed . There is extensive tumor infiltration of the adjacent fat planes and regional lymphadenopathy . (Right) Film from an upper GI series in the same patient confirms high-grade obstruction of the 2nd duodenum by a scirrhous mass , the primary duodenal carcinoma.

337

Duodenum

Duodenal Metastases and Lymphoma KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Involvement of duodenum with malignant lymphoma or metastatic disease

• Villous adenoma, duodenal carcinoma, secondary duodenal invasion, duodenal GIST

IMAGING

PATHOLOGY

• Best diagnostic clue ○ Metastases: Bull's-eye or "target" lesion; submucosal or polypoid mass ○ Lymphoma: Bulky submucosal mass without obstruction • Best imaging tool: Upper GI series, CECT • Metastases: "Target" or bull's-eye lesion with rounded submucosal mass ○ Luminal obstruction and ulceration are common • Lymphoma: Large smooth or lobulated submucosal mass ○ Aneurysmal dilation of lumen without obstruction • Direct invasion: From primary cancer of pancreas, colon, kidney, gallbladder

• Etiology ○ Metastases: Melanoma, cancer of breast, lung, colon, pancreas, or kidney ○ Lymphoma: Non-Hodgkin lymphoma of B-cell origin or mucosa-associated lymphoid tissue

(Left) Spot film from from an upper GI series shows an ulcerated mass arising from the 2nd portion of the duodenum. There is a persistent pooling of barium within the lesion after the remainder of the duodenum has cleared. (Right) Axial CECT in the same patient reveals a high-attenuation mass within the wall of the 2nd duodenum. A metastatic tumor was confirmed at surgery with the same histology as the primary colon cancer.

(Left) Small bowel followthrough in a liver transplant recipient, who presented with upper gastrointestinal pain and bleeding, shows a large amorphous collection of barium apparently arising from, and in continuity with, the distal duodenum. There is no evidence of bowel obstruction. (Right) Axial CECT in the same patient shows a large soft tissue density mass arising from the distal duodenum. This is a good example of aneurysmal dilation of the bowel lumen caused by lymphoma.

338

CLINICAL ISSUES • Most common signs/symptoms: Abdominal pain, nausea, vomiting, weight loss, palpable mass, upper GI bleeding

DIAGNOSTIC CHECKLIST • Consider duodenal carcinoma (usually obstructs lumen) • Lymphoma: Bulky submucosal mass without obstruction

Duodenal Metastases and Lymphoma

Definitions • Involvement of duodenum with malignant lymphoma or metastatic disease

IMAGING General Features • Best diagnostic clue ○ Metastases: Bull's-eye or "target" lesion; submucosal or polypoid mass ○ Lymphoma: Bulky submucosal mass without obstruction of lumen • Location ○ Submucosal lesion in any portion of duodenum • Morphology ○ Lymphoma: Smooth submucosal, often bulky mass

Fluoroscopic Findings • Upper GI ○ Metastases: "Target" or bull's-eye lesion with rounded submucosal mass; luminal obstruction and ulceration are common ○ Lymphoma: Large smooth or lobulated submucosal mass; aneurysmal dilation of lumen without obstruction

CT Findings • CECT ○ Hematogenous metastasis appears as rounded submucosal mass ○ Direct invasion from primary tumor of pancreas, colon, kidney, gallbladder, or retroperitoneal node ○ Lymphoma: Bulky hypovascular soft tissue mass – Stomach and duodenum may be involved contiguously

MR Findings • T1WI ○ Low signal duodenal mass • T2WI ○ Intermediate signal mass • T1WI C+ ○ Variable enhancement: Adenocarcinoma typically hypovascular; melanoma may be hypervascular

Imaging Recommendations • Best imaging tool ○ Upper GI series, CECT

DIFFERENTIAL DIAGNOSIS Villous Adenoma • Bulky mucosal polypoid mass (3-9 cm); rarely causes obstruction

Duodenal Carcinoma • More likely to appear as an "apple core," annular, obstructing lesion • Increased incidence in Gardner syndrome, celiac disease, Crohn disease, neurofibromatosis • Regional lymphadenopathy and pancreatic invasion are common

Secondary Duodenal Invasion • Most commonly due to pancreatic, colon, or renal cell carcinoma • Large extramural mass; often asymptomatic but may lead to outlet obstruction

Duodenum

TERMINOLOGY

Duodenal GIST • Large submucosal mass ± central ulceration • Duodenum is 2nd to stomach as site for GIST

PATHOLOGY General Features • Etiology ○ Metastases: Melanoma, cancer of breast, lung, colon, pancreas, or kidney ○ Lymphoma: Non-Hodgkin lymphoma of B-cell origin or mucosa-associated lymphoid tissue (MALT) • Associated abnormalities ○ Regional lymphadenopathy; metastases may cause outlet obstruction

Staging, Grading, & Classification • GI lymphoma staging ○ I: Tumor confined to bowel wall ○ II: Limited spread to local nodes ○ III: Widespread nodal metastases ○ IV: Spread to bone marrow, solid viscera (e.g., liver)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, nausea, vomiting, weight loss, palpable mass, upper GI bleeding

Demographics • Age ○ 55-60 years • Gender ○ M 85%, specificity > 95%, accuracy ~ 85-88% ○ Accumulation of isotope in RLQ on positive scans ○ Pentagastrin used to stimulate MD gastric mucosal uptake – When initial scintigraphy is equivocal or normal ○ False-positive results: Gastric ectopia, appendicitis, inflammatory bowel disease ○ False-negative results: Absent or minimal ectopic gastric mucosa

Imaging Recommendations • Fluoroscopic compression during enteroclysis • CT for symptomatic (pain, tenderness) in adults • Tc-99m scintigraphy in bleeding cases (children)

DIFFERENTIAL DIAGNOSIS Appendicitis • Best imaging clue on CT ○ Appendicolith (usually calcified) within distended tubular appendix • Mural thickening of appendix with surrounding inflammation (fat stranding) • ± right lower quadrant (RLQ) lymphadenopathy • In perforated cases ○ Fluid collection most commonly in RLQ or dependent pelvis (cul-de-sac) ○ Abscess, small bowel obstruction • Clinically and radiographically may mimic MD • Differentiation often made only at surgery

Crohn Disease • • • •

Involves distal ileum in most cases ± skip lesions Mural thickening, luminal narrowing Bright enhancement of mucosa and mesenteric hyperemia Perforated Crohn ileitis could mimic perforated MD

Mesenteric Adenitis and Enteritis • Another common cause of RLQ pain 353

Small Intestine

Meckel Diverticulum ○ Predominantly in children and adolescents • Inflammation of mesenteric nodes ± distal ileum • Imaging findings ○ Enlarged, clustered adenopathy in mesentery and RLQ ○ May also have ileal wall thickening • Usually resolves spontaneously within 2 days

Cecal Diverticulitis • Perforation and localized pericolic inflammation • Imaging findings ○ Cecal wall thickening, fat stranding, free fluid and air ○ Bowel outpouching filled with air, contrast, feces ○ Acute: Enhancement of thickened colonic wall • Clinical presentation ○ RLQ pain, fever, tenderness ○ More common in middle-aged and elderly • May mimic complicated MD clinically and radiologically

PATHOLOGY General Features • Etiology ○ Early fetal life: Primitive mid-gut communicates with yolk sac through vitelline duct – Failure of usual complete regression leads to anomalies – Failure of vitelline duct to involute Meckel diverticulum • Embryology-anatomy ○ Persistent omphalomesenteric or vitelline duct, which usually obliterates by 5th embryonic week

Gross Pathologic & Surgical Features • Solitary diverticulum located ~ 50-60 cm proximal to ileocecal valve on antimesenteric border • May contain enteroliths, bezoars, or ingested foreign bodies

Natural History & Prognosis • Complications ○ GI bleeding ○ Diverticulitis, perforation, abscess ○ Enteroliths and bezoars may collect within MD ○ Obstruction due to intussusception or volvulus ○ Extrusion of diverticulum into inguinal hernia ○ Inverted MD: Acts like polypoid mass intussusception bowel obstruction ○ Rare development of carcinoma within MD • Prognosis: Good after surgery

Treatment • Asymptomatic: No treatment • Symptomatic: Surgical resection

DIAGNOSTIC CHECKLIST Consider • Rule out other inflammatory conditions of RLQ

Image Interpretation Pearls • Enteroclysis: Blind-ended sac on antimesenteric border of ileum with broad base or narrow neck • Meckel diverticulitis: CT shows mural thickening, mesenteric fat infiltration, and fluid ± enteroliths

SELECTED REFERENCES 1. 2. 3. 4.

Microscopic Features

5.

• Composed of all layers of GI tract (true diverticulum) • Ectopic gastric or pancreatic mucosa may be seen

6.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Mostly asymptomatic ○ 5% likelihood of becoming symptomatic during lifetime – Pain in RLQ most common ○ Children: Present with GI bleeding before age 2 ○ Adults: Present with diverticulitis or small bowel obstruction ○ Causes of bowel obstruction – Large diverticulum – Mass effect by enteroliths or bezoar – Inflammation causing spasm of adjacent SB segment

Demographics • Age ○ Any age group • Gender ○ M:F = 3:1 354

• Epidemiology ○ Prevalence (0.3-3%)

7. 8. 9. 10. 11. 12. 13. 14. 15.

Bingham JR et al: Phytobezoar within Meckel's diverticulum: an unusual cause of intestinal obstruction. Am Surg. 80(3):E94-6, 2014 Cantrell EF et al: Small bowel obstruction secondary to impacted phytobezoar within a Meckel's diverticulum. Am Surg. 80(7):e194-5, 2014 Kim SW et al: MDCT findings of a Meckel's diverticulum with ectopic pancreatic tissue. Clin Imaging. 38(1):70-2, 2014 Caillouët IS et al: Torsion and gangrene of a Meckel's diverticulum. J La State Med Soc. 161(1):19-22; quiz 23, 54, 2009 Kiratli PO et al: Detection of ectopic gastric mucosa using 99mTc pertechnetate: review of the literature. Ann Nucl Med. 23(2):97-105, 2009 Lucha P: Meckel's diverticulitis with associated enterloith formation: a rare presentation of an acute abdomen in an adult. Mil Med. 174(3):331-3, 2009 Ozdemir S et al: A case report of intestinal obstruction due to phytobezoar within Meckel's diverticulum. Turk J Gastroenterol. 20(1):76-7, 2009 Thurley PD et al: Radiological features of Meckel's diverticulum and its complications. Clin Radiol. 64(2):109-18, 2009 Bennett GL et al: CT of Meckel's diverticulitis in 11 patients. AJR Am J Roentgenol. 182(3):625-9, 2004 Murakami R et al: Strangulation of small bowel due to Meckel diverticulum: CT findings. Clin Imaging. 23(3):181-3, 1999 Mitchell AW et al: Meckel's diverticulum: angiographic findings in 16 patients. AJR Am J Roentgenol. 170(5):1329-33, 1998 Pantongrag-Brown L et al: Inverted Meckel diverticulum: clinical, radiologic, and pathologic findings. Radiology. 199(3):693-6, 1996 Pantongrag-Brown L et al: Meckel's enteroliths: clinical, radiologic, and pathologic findings. AJR Am J Roentgenol. 167(6):1447-50, 1996 Rossi P et al: Meckel's diverticulum: imaging diagnosis. AJR Am J Roentgenol. 166(3):567-73, 1996 Maglinte DD et al: Meckel diverticulum: radiologic demonstration by enteroclysis. AJR Am J Roentgenol. 134(5):925-32, 1980

Meckel Diverticulum Small Intestine

(Left) Axial CT shows a dilated small bowel with wall thickening of a distal segment. An adjacent blindending sac represents the Meckel diverticulum and it contains calcified enteroliths in its dependent portion. Meckel diverticulitis was confirmed at surgery. (Right) Coronal reformatted CT in the same case shows the inflamed and obstructed SB segment that was adherent to the Meckel diverticulum.

(Left) Film from a barium small bowel follow-through shows a blind-ending pouch arising from distal ileum. Barium mixes with enteric debris within the diverticulum, which shows no evidence of obstruction or perforation. Like most Meckel diverticula, especially in adults, this one was probably an asymptomatic incidental finding. (Right) Tc-99m pertechnetate scan from a child with GI bleeding and pain shows accumulation of isotope in the RLQ due to ectopic gastric mucosa within a Meckel diverticulum.

(Left) Axial CECT in a 17-yearold girl with painful abdominal cramps and RLQ tenderness shows a distal ileal intussusception . (Right) Axial CECT in the same patient shows a long-segment intussusception with dilation of the SB upstream, due to obstruction. An inverted Meckel diverticulum was found as the lead mass at surgery.

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Small Intestine

Mesenteric Adenitis and Enteritis KEY FACTS

TERMINOLOGY • Benign inflammation of lymph nodes in ileocolic mesentery, often with terminal ileitis

IMAGING • Cluster of mildly enlarged ileocolic mesenteric lymph nodes ( 5 mm) ○ Mesenteric adenopathy is often much more evident on coronal-reformatted CT • Ileal ± cecal wall thickening, sometimes with regional ileus ○ Mucosal hyperenhancement, submucosal edema • Normal-appearing appendix

TOP DIFFERENTIAL DIAGNOSES • Appendicitis • Crohn disease ○ Early Crohn disease may be impossible to distinguish ○ Time course and likelihood of recurrence are different • Cecal or appendiceal carcinoma

(Left) Axial CT in a 25-year-old woman presenting with fever and RLQ tenderness shows wall thickening and mucosal hyperenhancement of the terminal ileum and cecum . (Right) Another CT section in the same patient shows a normal appendix , excluding appendicitis as the diagnosis.

(Left) Coronal-reformatted image in the same patient shows a cluster of mildly enlarged ileocolic mesenteric nodes , along with the thick-walled, inflamed terminal ileum . (Right) Another coronal CECT section shows enlarged nodes and engorged vessels in the ileocolic mesentery , along with the thick-walled terminal ileum. These are classic imaging and CT features of mesenteric adenitis and enteritis, and the patient made an uneventful recovery without specific therapy.

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○ Affects older adults, not children

PATHOLOGY • Reactive lymph node enlargement secondary to enteric pathogens • Viral (most common) • Bacterial (especially Yersinia and Campylobacter species)

CLINICAL ISSUES • Commonly seen in children and young adults < 25 years old ○ 8-12% of young patients with acute RLQ pain have mesenteric adenitis • Pain, fever, nausea, vomiting ○ Leukocytosis • Self-limited, usually resolves without treatment

Mesenteric Adenitis and Enteritis

Definitions • Benign inflammation of lymph nodes in ileal mesentery, often with terminal ileitis

IMAGING General Features • Best diagnostic clue ○ Cluster of slightly prominent ( 5 mm) mesenteric lymph nodes in right lower quadrant (RLQ) ○ Ileal/ileocolic wall thickening ○ Normal-appearing appendix • Size ○ Nodes 5 mm in short axis ○ Rarely exceed 10 mm ○ Clustered ( 3 nodes)

• Affects older adults, not children

PATHOLOGY General Features • Etiology ○ Viral (most common) ○ Bacterial: Yersinia enterocolitica, Yersinia pseudotuberculosis, Helicobacter pylori, Campylobacter jejuni, Salmonella, Shigella ○ Mycobacterial • Associated abnormalities ○ Ileitis, ileocolitis • Pathophysiology ○ Reactive lymph node enlargement secondary to enteric pathogens

CLINICAL ISSUES

Imaging Recommendations

Presentation

• Best imaging tool ○ CECT with coronal reformations • Regional ileus, bowel wall thickening may be seen

• Most common signs/symptoms ○ Pain, fever, nausea, vomiting ○ Leukocytosis • Other signs/symptoms ○ Diarrhea, RLQ tenderness

Ultrasonographic Findings

Demographics

• • • •

• Age ○ Commonly seen in children and young adults < 25 years old ○ Concurrent enteric disease commonly seen in children, especially those < 5 years old • Epidemiology ○ 8-12% of young patients presenting with acute RLQ pain have mesenteric adenitis

Radiographic Findings

Nodal tenderness in response to transducer pressure Round and hypoechoic nodes measuring 5 mm Terminal ileal wall thickening may be seen Nonvisualization of inflamed appendix

CT Findings • Cluster of mildly enlarged ileocolic mesenteric lymph nodes ( 5 mm) ○ Mesenteric adenopathy is often much more evident on coronal-reformatted CT • Bowel wall thickening of terminal ileum ± cecum ○ Mucosal hyperenhancement and submucosal edema – More evident with water as oral contrast agent ○ ± engorged ileocolic vessels • Normal appendix

DIFFERENTIAL DIAGNOSIS

Natural History & Prognosis • Self-limited, usually resolves without treatment • Concurrent enterocolitis may be severe (rarely)

Treatment • Conservative, nonoperative management

DIAGNOSTIC CHECKLIST

Appendicitis

Consider

• May have similar cluster of nodes • Thick-walled appendix with mural and mucosal enhancement ○ Periappendiceal inflammation • Total diameter of appendix > 7 mm • Appendicolith often seen on CT (33-50%)

• Mesenteric adenitis is diagnosis of exclusion

Crohn Disease • Segmental areas of ileo-colonic ulceration • Discontinuous and asymmetric bowel wall thickening (> 1 cm) • More mesenteric hyperemia (comb sign) • History of prior similar episodes of pain in most cases

Cecal or Appendiceal Carcinoma

Small Intestine

TERMINOLOGY

SELECTED REFERENCES 1. 2.

3.

4. 5. 6.

Patlas MN et al: Cross-sectional imaging of nontraumatic peritoneal and mesenteric emergencies. Can Assoc Radiol J. 64(2):148-53, 2013 Toorenvliet B et al: Clinical differentiation between acute appendicitis and acute mesenteric lymphadenitis in children. Eur J Pediatr Surg. 21(2):120-3, 2011 Lee MW et al: Sonography of acute right lower quadrant pain: importance of increased intraabdominal fat echo. AJR Am J Roentgenol. 192(1):174-9, 2009 Pickhardt PJ et al: Unusual nonneoplastic peritoneal and subperitoneal conditions: CT findings. Radiographics. 25(3):719-30, 2005 Rao PM et al: CT diagnosis of mesenteric adenitis. Radiology. 202(1):145-9, 1997 Puylaert JB: Mesenteric adenitis and acute terminal ileitis: US evaluation using graded compression. Radiology. 161(3):691-5, 1986

• Also associated with RLQ clustered nodes • Look for soft tissue mass and omental metastases 357

Small Intestine

Intestinal Parasites and Infestation KEY FACTS

TERMINOLOGY • Enteric infection with roundworm Ascaris lumbricoides (ascariasis) • Enteric protozoal infection with ○ Giardia lamblia (giardiasis) ○ Cryptosporidium (cryptosporidiosis) ○ Entamoeba histolytica (amebiasis)

IMAGING • Best diagnostic clue ○ Ascariasis: Linear filling defect on small bowel followthrough (SBFT) ○ Giardiasis and cryptosporidiosis – Thickened duodenal and jejunal folds on SBFT ○ Amebiasis: Diffuse ulcerating colitis, right lobe liver abscess on CECT • Location ○ Small bowel (SB), colon, CBD, or pancreatic duct (ascariasis)

(Left) Axial CECT with intravenous and oral contrast in a 19-year-old woman from Mexico status post motor vehicle crash reveals linear filling defects in the proximal small bowel. These defects represent the roundworm Ascaris lumbricoides. (Right) Anteroposterior view of a small bowel follow-through (SBFT) demonstrates thickened folds in the proximal jejunum from giardiasis.

(Left) SBFT in a 40-year-old man who recently immigrated from India, now presenting with abdominal pain and diarrhea, demonstrates long curvilinear filling defects within the small bowel, essentially diagnostic of Ascaris infestation. (Right) Small bowel barium study reveals Ascaris as a longitudinal filling defect in the distal small bowel .

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○ Duodenum, jejunum (giardiasis) ○ Colon, liver (amebiasis) • Best imaging tool ○ SBFT (ascariasis, giardiasis, and cryptosporidiosis) ○ Barium enema, CECT (amebiasis)

TOP DIFFERENTIAL DIAGNOSES • Crohn disease • Ulcerative colitis

CLINICAL ISSUES • Ascariasis infests 25% of world population • Giardiasis and cryptosporidiosis: Most common protozoal diseases in USA • Amebiasis infests 10% of world population

DIAGNOSTIC CHECKLIST • Consider Crohn disease, ulcerative colitis

Intestinal Parasites and Infestation

Definitions • Enteric infection with roundworm Ascaris lumbricoides • Enteric protozoal infection with Giardia lamblia, Cryptosporidium, or Entamoeba histolytica

IMAGING General Features • Best diagnostic clue ○ Ascariasis: Linear filling defect on SBFT ○ Giardiasis and cryptosporidiosis: Thickened duodenal/jejunal folds on SBFT ○ Amebiasis: Diffuse ulcerating colitis, right lobe liver abscess on CECT • Location ○ Small bowel (SB), colon, common bile duct (CBD), or pancreatic duct (ascariasis) ○ Duodenum and jejunum (giardiasis) ○ Colon or liver (amebiasis)

Radiographic Findings • Radiography ○ Ascariasis: Soft tissue mass from coiled worms at ileocecal valve ○ May progress to SB obstruction (SBO)

Fluoroscopic Findings • Barium studies ○ Linear filling defects up to 35 cm long in SB (ascariasis) ○ Thickened duodenal and jejunal folds (giardiasis and cryptosporidiosis); colon ulcerations (amebiasis)

CT Findings • CECT ○ Ascariasis: Linear or mass-like filling defects in SB, biliary obstruction, pancreatitis ○ Amebic colitis: Mucosal hyperenhancement, submucosal edema ± solitary nonseptate liver abscess ○ Giardiasis and cryptosporidiosis: SB wall thickening and submucosal edema

Imaging Recommendations • Best imaging tool ○ SBFT (ascariasis and giardiasis); barium enema, CECT (amebiasis)

DIFFERENTIAL DIAGNOSIS Crohn Disease • Aphthous ulcers, skip areas of SB and colon, sinus tracts into mesentery, fibrofatty extramural masses

Ulcerative Colitis • Superficial ulcers, granular mucosa, long-segment strictures, rectal involvement

PATHOLOGY Microscopic Features

• Giardiasis: Villous blunting, inflammatory cells in lamina propria • Amebiasis: Colitis with neutrophilic infiltrate and deep ulcers into submucosa

CLINICAL ISSUES

Small Intestine

TERMINOLOGY

Presentation • Most common signs/symptoms ○ Ascariasis: Abdominal pain, diarrhea (may be asymptomatic); biliary invasion may cause obstruction and cholangitis ○ Giardiasis and cryptosporidiosis: Abdominal pain, diarrhea, nausea, vomiting, distension, weight loss, malabsorption ○ Amebiasis: Diarrhea, fever, GI bleeding

Demographics • Epidemiology ○ Ascariasis infests 25% of world population (especially Africa and Asia) ○ Cryptosporidiosis and giardiasis are most common protozoal diseases in USA; ~ 2-5% of general population, higher in immunosuppressed patients ○ Amebiasis infests 10% of world population – Especially in developing countries with poor sanitation – Up to 10% of Mexican population is seropositive for E. histolytica – Most cases seen in developed countries occur in immigrants from endemic areas

Natural History & Prognosis • Ascariasis: SBO, appendicitis, pancreatitis • Protozoal infection: Usually self-limited in immune competent; may be life-threatening in immunosuppressed • Amebic infection: Usually asymptomatic ○ Invasive disease occurs much more frequently in children and in patients who are malnourished, immunosuppressed, or have other diseases

Treatment • Options, risks, complications ○ Ascariasis: Anthelminthic chemotherapy with mebendazole, albendazole, or pyrantel pamoate ○ Giardiasis and cryptosporidiosis: Nitazoxanide or metronidazole – Most cases need only supportive care – Immune restoration with HAART usually causes resolution of symptoms in HIV patients ○ Amebiasis: Metronidazole

DIAGNOSTIC CHECKLIST Consider • Consider Crohn disease, ulcerative colitis

SELECTED REFERENCES 1.

Ruankham W et al: Prevalence of helminthic infections and risk factors in villagers of Nanglae Sub-District, Chiang Rai Province, Thailand. J Med Assoc Thai. 97 Suppl 4:S29-35, 2014

• Ascariasis: Mucosal destruction at worm attachment sites; inflammatory changes in appendix, pancreas, biliary tree 359

Small Intestine

Opportunistic Intestinal Infections KEY FACTS

TERMINOLOGY • Symptomatic gastrointestinal (GI) infection of immunocompromised host by organisms that usually cause no or minor illness in immunocompetent individuals

IMAGING • Cytomegalovirus (CMV) ○ Favors distal small bowel (SB) and colon ○ Mucosal hyper- or hypoenhancement; submucosal edema ○ Infiltration of mesenteric fat ○ Lymphadenopathy is very uncommon • Mycobacterial ○ Mycobacterium avium-intracellulare (MAI): Thickened SB folds with relatively little submucosal edema ○ Tuberculosis (TB): Favors ileocecal distribution ○ Mesenteric lymphadenopathy, often with low density (caseation) ○ Exudative ascites (may mimic peritoneal carcinomatosis)

(Left) This young woman has cystic fibrosis and lung transplantation, with new onset diarrhea. Axial CECT shows hyperenhancement and submucosal edema affecting most of the small bowel (SB). (Right) Coronal CECT in the same patient shows the widespread enteritis with engorged mesenteric vessels . The colon is spared. Endoscopy and biopsy confirmed cytomegalovirus (CMV) enteritis.

(Left) This 35-year-old man with AIDS developed profuse diarrhea and abdominal pain. Axial CECT shows pancolitis with marked submucosal edema but no hyperenhancement of the mucosa. (Right) Coronal CECT in the same patient shows more evidence of pancolitis , proven to be due to CMV, which may induce ischemic injury to both the SB and colon in immunocompromised patients.

360

• Protozoan (Cryptosporidium,Microsporidia, and Giardia) ○ Duodenum and jejunum, sparing distal SB and colon ○ Fold thickening without much submucosal edema ○ Excess fluid (luminal distention) of proximal small bowel ○ No ascites; uncommon lymphadenopathy • Bacterial (Clostridium difficile colitis, Campylobacter, and others) ○ Segmental or, more commonly, pancolitis ○ Striking mucosal hyperenhancement and submucosal edema ○ Ascites (present in 40% of cases) ○ May progress to toxic megacolon or perforation

TOP DIFFERENTIAL DIAGNOSES • Gastrointestinal lymphoma

CLINICAL ISSUES • Prevalence of opportunistic GI infections in HIV patients has markedly decreased with potent antiretroviral therapy

Opportunistic Intestinal Infections

Definitions • Symptomatic gastrointestinal (GI) infection of immunocompromised host by organisms that usually cause no or minor illness in immunocompetent individuals

IMAGING General Features • Best diagnostic clue ○ Cytomegalovirus (CMV): Mucosal hyper- or hypoenhancement; submucosal edema – Distribution: Small bowel (SB), colon > stomach, esophagus, rectum □ Favors distal small bowel and colon – Pattern CECT: Mucosal hyper- or hypoenhancement □ Reflects active inflammation vs. ischemic necrosis □ Deep ulcers may be transmural, causing mesenteric infiltration – Pattern on upper GI series, small bowel series, or barium enema □ Aphthoid erosions in earlier stages □ Deep ulcers, even sinus tracts in later stages – Barium studies and CT findings may mimic Crohn disease or ulcerative colitis – Associated findings □ Lymphadenopathy is very uncommon □ Infiltration of mesenteric fat by transmural, deep ulceration ○ Mycobacterial – Mycobacterium avium-intracellulare (MAI): Thickened SB folds with relatively little submucosal edema □ Micronodular fold thickening on SB follow-through – Tuberculosis (TB) □ Favors ileocecal distribution □ Wall thickening, luminal narrowing, ± obstruction – Associated findings □ Mesenteric lymphadenopathy, often with low density (caseation) □ Exudative ascites (peritonitis) □ Peritoneal and omental thickening (may mimic peritoneal carcinomatosis) □ Most affected patients do not have overt lung disease ○ Protozoan (Cryptosporidium and Giardia) – Distribution □ Duodenum and jejunum □ Ileum and colon are spared – Pattern □ Fold thickening without much submucosal edema □ Excess fluid (luminal distention) of proximal small bowel – Associated findings □ No ascites nor lymphadenopathy ○ Bacterial (Clostridium difficile colitis, Campylobacter, and others) – Distribution □ Segmental or, more commonly, pancolitis □ Terminal ileum affected uncommonly – Pattern

□ Striking mucosal hyperenhancement □ Marked submucosal edema (target or accordion sign) – Associated findings □ Ascites (present in 40% of cases) □ May progress to toxic megacolon or perforation □ No lymphadenopathy

Small Intestine

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Multiplanar CECT • Protocol advice ○ IV contrast at > 3 mL/sec; image at 60 seconds; view in multiple planes ○ Oral contrast is rarely useful (makes determination of mucosal enhancement impossible)

DIFFERENTIAL DIAGNOSIS Gastrointestinal Lymphoma • Most commonly non-Hodgkin lymphomas, high-grade large cell or immunoblastic cell types ○ Burkitt more common in pediatric patients • Most common symptoms: Abdominal pain, weight loss, fever, anemia ○ Not diarrhea • Soft tissue density wall thickening ○ Without luminal obstruction or submucosal edema • May be multifocal; SB and colon • Often with bulky, widespread lymphadenopathy • Ascites is rare

PATHOLOGY General Features • Etiology ○ CMV – Occurs in severely immunocompromised patients □ e.g., HIV patients with CD4 counts < 50 cells/μL □ Prevalence has deceased markedly with use of potent antiretroviral therapy (HAART) – Causes vasculitis leading to GI ulceration, ischemia, bleeding, perforation ○ Mycobacteria – Atypical MAI and TB – May be newly acquired in immunocompromised patient □ Or reactivation of prior quiescent infection – Macrophages infiltrate lamina propria of SB, distending villi ○ Cryptosporidium, Microsporidia, and Giardia – May affect immunocompetent individuals, usually less severely – Protozoan organisms attach between microvilli of small intestine – Leads to mucosal damage and secretory enteritis and diarrhea ○ Infectious colitis – May affect immunocompetent patients as well □ Usually nosocomial infection □ Often preceded by antibiotic use 361

Small Intestine

Opportunistic Intestinal Infections

– C. difficile is most common □ Campylobacter, Escherichia coli, and others may occur

Microscopic Features • CMV ○ Cytoplasmic inclusion bodies in enterocytes, macrophages, fibroblasts, and endothelial cells ○ May induce ischemic necrosis of bowel mucosa • MAI ○ Coarsely granular mucosa ○ Sheets of foamy macrophages infiltrate lamina propria ○ Positive acid-fast or Fite stain for organisms • Cryptosporidiosis ○ Organisms proliferate from apex of enterocyte ○ Villous atrophy ○ Crypt hyperplasia ○ Inflammatory infiltrate

CLINICAL ISSUES

• Diagnosis depends on microbiological confirmation by analysis of bowel content or even biopsy

Image Interpretation Pearls • CMV: Deep ulcerations and focal enteritis or colitis • Mycobacterial infection: Enteritis and low-attenuation lymphadenopathy • Cryptosporidiosis: Thickened bowel wall and edematous folds

SELECTED REFERENCES 1. 2. 3. 4. 5.

6.

Presentation • Most common signs/symptoms ○ Abdominal pain, nausea, diarrhea, fever, GI bleeding ○ Symptoms are often masked by medications or suppressed immune status – May be simulated by coexisting infections and neoplasms

7. 8. 9.

10.

Demographics • Age ○ Any age but elderly are more prone • Gender ○ M=F • Epidemiology ○ HIV or immunocompromised patient (e.g., transplant recipient, aggressive chemotherapy) ○ Patients with Crohn disease or ulcerative colitis – Treatment with biological agents, immune modulators (e.g., antitumor necrosis factor), corticosteroids – High prevalence of opportunistic infections in patients with inflammatory bowel disease

11.

Natural History & Prognosis

17.

• Many opportunistic intestinal infections clear spontaneously with recovery of functional immune competence • MAI in AIDS patients often difficult to treat

18.

Treatment • • • • •

CMV: Antiviral therapy with acyclovir or ganciclovir Mycobacterial: Antituberculous chemotherapy Cryptosporidiosis: Chemotherapy with nitazoxanide Microsporidiosis: Albendazole, metronidazole, and others Bacterial: Antibiotics ○ "Stool transplantation" in refractory cases to repopulate normal colonic biome

DIAGNOSTIC CHECKLIST Consider • Specific diagnosis can be suggested by CT 362

12.

13.

14.

15. 16.

19. 20. 21. 22. 23. 24.

Dave M et al: Opportunistic infections due to inflammatory bowel disease therapy. Inflamm Bowel Dis. 20(1):196-212, 2014 Pariente B et al: Review article: why, when and how to de-escalate therapy in inflammatory bowel diseases. Aliment Pharmacol Ther. 40(4):338-53, 2014 Curkovic I et al: Risks of inflammatory bowel disease treatment with glucocorticosteroids and aminosalicylates. Dig Dis. 31(3-4):368-73, 2013 Florescu DF et al: Opportunistic viral infections in intestinal transplantation. Expert Rev Anti Infect Ther. 11(4):367-81, 2013 Tonolini M et al: Acute HIV-related gastrointestinal disorders and complications in the antiretroviral era: spectrum of cross-sectional imaging findings. Abdom Imaging. 38(5):994-1004, 2013 Werneck-Silva AL et al: Gastroduodenal opportunistic infections and dyspepsia in HIV-infected patients in the era of Highly Active Antiretroviral Therapy. J Gastroenterol Hepatol. 24(1):135-9, 2009 Hampton DD et al: Inflammatory bowel disease following solid organ transplantation. Clin Immunol. 128(3):287-93, 2008 Ishida T et al: The management of gastrointestinal infections caused by cytomegalovirus. J Gastroenterol. 38(7):712-3, 2003 Koh DM et al: Abdominal computed tomographic findings of Mycobacterium tuberculosis and Mycobacterium avium intracellulare infection in HIV seropositive patients. Can Assoc Radiol J. 54(1):45-50, 2003 Brantsaeter AB et al: CMV disease in AIDS patients: incidence of CMV disease and relation to survival in a population-based study from Oslo. Scand J Infect Dis. 34(1):50-5, 2002 Hunter PR et al: Epidemiology and clinical features of Cryptosporidium infection in immunocompromised patients. Clin Microbiol Rev. 15(1):145-54, 2002 Masur H et al: Guidelines for preventing opportunistic infections among HIVinfected persons--2002. Recommendations of the U.S. Public Health Service and the Infectious Diseases Society of America. Ann Intern Med. 137(5 Pt 2):435-78, 2002 Oldfield EC 3rd: Evaluation of chronic diarrhea in patients with human immunodeficiency virus infection. Rev Gastroenterol Disord. 2(4):176-88, 2002 Ukarapol N et al: Cytomegalovirus-associated manifestations involving the digestive tract in children with human immunodeficiency virus infection. J Pediatr Gastroenterol Nutr. 35(5):669-73, 2002 von Reyn CF et al: Sources of disseminated Mycobacterium avium infection in AIDS. J Infect. 44(3):166-70, 2002 Huh JJ et al: Mycobacterium avium complex peritonitis in an AIDS patient. Scand J Infect Dis. 33(12):936-8, 2001 Pollok RC: Viruses causing diarrhoea in AIDS. Novartis Found Symp. 238:27683; discussion 283-8, 2001 Chamberlain RS et al: Ileal perforation caused by cytomegalovirus infection in a critically ill adult. J Clin Gastroenterol. 30(4):432-5, 2000 Clemente CM et al: Gastric cryptosporidiosis as a clue for the diagnosis of the acquired immunodeficiency syndrome. Arq Gastroenterol. 37(3):180-2, 2000 Wallace MR et al: Gastrointestinal manifestations of HIV infection. Curr Gastroenterol Rep. 2(4):283-93, 2000 Drew WL et al: Cytomegalovirus: disease syndromes and treatment. Curr Clin Top Infect Dis. 19:16-29, 1999 Lumadue JA et al: A clinicopathologic analysis of AIDS-related cryptosporidiosis. AIDS. 12(18):2459-66, 1998 Manabe YC et al: Cryptosporidiosis in patients with AIDS: correlates of disease and survival. Clin Infect Dis. 27(3):536-42, 1998 Rossi P et al: Gastric involvement in AIDS associated cryptosporidiosis. Gut. 43(4):476-7, 1998

Opportunistic Intestinal Infections Small Intestine

(Left) Axial CECT in a 34-yearold HIV-positive man presenting with diarrhea shows the typical appearance of CMV colitis. Note the diffuse thickening of the colon wall and mucosal hyperenhancement . (Right) Coronal CECT in the same patient illustrates the global nature of this colitis with involvement of the ascending and descending colon, as well as sigmoid . CMV colitis infects an immunocompromised host with a virus that causes vasculitis.

(Left) Axial CECT in a 28-yearold man with HIV and intractable diarrhea shows the typical appearance of Mycobacterium aviumintracellulare (MAI) enteritis. Note the diffuse small bowel wall thickening and mesenteric adenopathy . (Right) This young woman is HIV-positive with new onset diarrhea. Axial CECT shows fluid distention of both small and large bowel , along with mesenteric lymphadenopathy . Cryptosporidium was the causative organism and typically causes diarrhea.

(Left) This man has a functioning renal allograft and developed acute bloody diarrhea due to Clostridium difficile. Axial NECT shows massive submucosal edema of the entire colon (pancolitis) with some segments having an "accordion" appearance . (Right) Axial NECT in the same patient shows ascites and mesenteric edema. Note the atrophic native kidneys . In spite of prompt diagnosis and treatment, the colitis progressed to perforation and emergency colectomy.

363

Small Intestine

Celiac-Sprue Disease KEY FACTS

• Celiac disease: Chronic intolerance of gluten that induces intestinal injury in genetically predisposed individuals

○ Excess gas, fluid, fat within lumen • Eccentric soft tissue density mass in bowel wall ○ Strongly suggests lymphoma or carcinoma

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• CT findings • SB wall may be thick or thinned ○ Mucosal hyperenhancement accompanies active ulceration ○ Reversal of jejunoileal fold patterns (atrophied jejunal, thickened ileal) ○ Submucosal edema, fat, or gas ○ Small bowel intussusception ○ Eccentric soft tissue density mass in bowel wall (tumor) ○ Mesenteric adenopathy (may be cavitated) • Excess fluid within SB lumen ○ Conformation of flaccid SB segments ○ Distends lumen and dilutes contrast medium • Colonic luminal dilation

• Whipple disease • Crohn disease • Intestinal opportunistic infections

TERMINOLOGY

(Left) Axial CECT in a 37-yearold man with painful abdominal cramps shows 1 of several sites of intussusception , typically short segment and nonobstructing. (Right) Axial CECT in the same patient demonstrates that the jejunal fold pattern seems blunted. Also noted is mesenteric lymphadenopathy .

(Left) Axial CECT in the same patient shows more mesenteric lymphadenopathy along with the abnormally blunted jejunal fold pattern. (Right) Axial CECT in the same patient shows another intussusception . There is a suggestion of abnormal fold prominence in the ileum . The flaccid, dilated pelvic SB loops press on each other without intervening space, known as the conformation sign.

364

CLINICAL ISSUES • Common: Affects 1 in 200 in USA, but < 10% are currently diagnosed ○ Most common cause of SB disease and malabsorption • Steatorrhea, abdominal distension, flatulence ○ Diarrhea, weight loss, glossitis, anemia • Refractory disease ○ Enteritis that does not respond to at least 6 months of gluten-free diet ○ GI malignancies are main cause of death in celiac disease

Celiac-Sprue Disease

Synonyms • Nontropical sprue or celiac-sprue disease, gluten-sensitive enteropathy

Definitions • Celiac disease: Chronic intolerance of gluten that induces intestinal injury in genetically predisposed individuals

IMAGING General Features • Best diagnostic clue ○ CT enterography: Evidence of reversed fold pattern, multifocal intussusception • Other general features ○ Most common small bowel disease producing malabsorption syndrome ○ Due to sensitivity of small bowel to -gliadin – Component of gluten ○ Has familial susceptibility with genetic basis

Radiographic Findings • Barium small bowel follow-through (SBFT) ○ Dilatation of small bowel (jejunum): > 3 cm ○ Hypersecretion-related artifacts: Due to excess fluid – Flocculation: Coarse granular appearance of small clumps of disintegrated barium due to excess fluid; mainly in patients with steatorrhea – Segmentation: Break up of normal continuous column of barium, creating large clumps of barium separated by string-like strands ○ Transit time: May be long, short, or normal ○ Nonpropulsive peristalsis (flaccid and poorly contracting bowel loops) • Fluoroscopic-guided enteroclysis ○ More accurate than SBFT in diagnosing celiac disease ○ Jejunal folds – Decreased number of proximal jejunal folds (< 3/inch; normal: 5/inch) – Increased separation and absence of folds; "ileal" appearance ○ Ileal folds – Increased number of folds in distal ileum (4-6/inch; normal: 2-4/inch) – Increased fold thickness 1 mm: "Jejunization" of ileum in 78% of cases

CT Findings • Excess fluid within SB lumen ○ Distends lumen and dilutes positive enteric contrast medium • SB wall may be thick or thinned ○ Mucosal hyperenhancement accompanies active ulceration ○ Submucosal edema; halo sign ○ Submucosal fat in wall of duodenum and jejunum ○ Pneumatosis has been reported (not due to ischemia) • Conformation of SB segments ○ Dilated, flaccid loops press against each other (especially in pelvis)

• Engorged mesenteric blood vessels • ± SB intussusception (bowel-within-bowel appearance) ○ Usually short segment, nonobstructing • Reversal of jejunal and ileal fold patterns ○ Jejunal folds atrophied; ileal folds increased • Mesenteric lymphadenopathy ○ Nodes may have cavitated appearance with central necrosis/liquefaction • Eccentric soft tissue density mass in bowel wall ○ Strongly suggests lymphoma or carcinoma • Colonic luminal dilation ○ Excess gas, fluid, fat within lumen (best seen on lung windows) ○ Colonic wall may appear thickened due to encrustation by fatty feces ○ "Geode" formation: Rock-like aggregations of fat, fluid, and gas • Hyposplenism (with decreased size of spleen)

Small Intestine

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CT enterography or CT enteroclysis • Protocol advice ○ CT enteroclysis – Pass nasojejunal tube, infuse (via pump) water at 150 mL/min to volume of 1,500-2,000 mL – 1 min prior to water infusion, give parenteral antispasmodic (e.g., glucagon) – Give IV contrast material (125 mL at 3 mL/sec) – View axial and reformatted (coronal) images

DIFFERENTIAL DIAGNOSIS Whipple Disease • Thickening of mesentery and lymphadenopathy • Periodic acid-Schiff (PAS) stain-positive material on mucosal biopsy • Electron microscopy:Tropheryma whippleii bacteria

Crohn Disease • Predominantly involves distal ileum and colon • Causes mucosal ulceration and hyperemia, submucosal edema • Does not cause malabsorption pattern on SBFT

Intestinal Opportunistic Infections • AIDS (e.g., cryptosporidiosis, tuberculosis, CMV) • Cryptosporidiosis ○ Most common cause of enteritis in AIDS patients ○ Thickening of folds and bowel wall; fluid in lumen • Enteric tuberculosis ○ Example: (Atypical) Mycobacterium avium-intracellulare ○ Small bowel shows thickened folds, fine nodularity ○ CT: Low-density (caseated) lymph nodes • Cytomegalovirus (CMV) ○ Causes terminal ileitis in AIDS patients ○ Narrow lumen, thickened folds, spiculation, ulcers

Ischemic Enteritis • Mucosal hyper- or hypoenhancement ○ Submucosal edema or gas (pneumatosis) • Thrombosis of superior mesenteric artery or vein 365

Small Intestine

Celiac-Sprue Disease

• Waldenstrom macroglobulinemia • IgA deficiency ○ Often accompanied by opportunistic infections (e.g., Giardia) ○ Both can cause nodular SB folds and malabsorption pattern

PATHOLOGY General Features • Etiology ○ Celiac disease: T-cell-mediated autoimmune response to ingested gluten ○ Tropical sprue: Unknown etiology; may be due to enteropathic E. coli • Genetics ○ Celiac disease: Class II human leukocyte antigens – HLA-DR3 and HLA-DQw2 • Associated abnormalities ○ Dermatitis herpetiformis; IgA deficiency ○ Hyposplenism ○ Cavitary mesenteric lymph node syndrome (rare) ○ Tropical sprue – Similar to celiac disease; affects entire small bowel

Gross Pathologic & Surgical Features • Ulceration and villous atrophy of duodenum and jejunum

Microscopic Features • Villous atrophy, thickened lamina propria, increased number of crypts and cellular infiltrate • Immunoperoxidase shows immunocytes with IgA and IgM antigliadin antibodies

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Malabsorption, steatorrhea, abdominal distension, flatulence ○ Diarrhea, weight loss, glossitis, anemia • Clinical profile ○ Young patient with history of steatorrhea, abdominal distension, and diarrhea • Lab data ○ Specific screening tests: IgG antigliadin and IgA antiendomysial antibodies in serum ○ Positive Sudan stain for fecal fat and D-xylose absorption ○ iron, folate, Ca++, K+, albumin, cholesterol levels • Diagnosis ○ Duodenojejunal mucosal biopsy ○ Clinical and imaging response to gluten-free diet

Demographics • Age ○ 1st peak by age of 2 years ○ 2nd peak in 3rd and 4th decades • Gender ○ M=F • Epidemiology 366

○ Common: Affects 1 in 200 in USA, but < 10% are currently diagnosed ○ Most common SB disease and cause of malabsorption ○ Celiac disease: Increased incidence in Ireland and Northern Europe; unknown in Africa, China, Japan ○ Tropical sprue: Increased incidence in tropics, especially in Vietnam and Puerto Rico

Immunologic Disorders

Natural History & Prognosis • Natural history ○ Adult disease: Extension of childhood form or new onset • Complications ○ Refractory disease – Symptomatic severe enteritis that does not respond to at least 6 months of gluten-free diet – These are patients at most risk for complications ○ Ulcerative jejunoileitis ○ risk of T-cell lymphoma and carcinoma of jejunum – GI malignancies are main cause of death in celiac disease □ Cause 50% of deaths in patients with refractory disease ○ Deep venous thrombosis • Prognosis ○ Celiac disease: Improvement within 48 hours; full remission (weeks to months) – Response to gluten-free diet ○ Tropical sprue: Improvement in 4-7 days; complete recovery (6-8 weeks)

Treatment • Nontropical sprue or celiac disease ○ Lifelong gluten-free diet • Tropical sprue ○ Broad spectrum antibiotics (tetracycline) and folates

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Imaging findings will vary according to duration and severity of disease

SELECTED REFERENCES 1. 2. 3. 4. 5.

6.

Malamut G et al: Refractory celiac disease. Expert Rev Gastroenterol Hepatol. 8(3):323-8, 2014 Mooney PD et al: Coeliac disease. BMJ. 348:g1561, 2014 Soyer P et al: Celiac disease in adults: evaluation with MDCT enteroclysis. AJR Am J Roentgenol. 191(5):1483-92, 2008 Scholz FJ et al: Intramural fat in the duodenum and proximal small intestine in patients with celiac disease. AJR Am J Roentgenol. 189(4):786-90, 2007 Paulsen SR et al: CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases. Radiographics. 26(3):641-57; discussion 657-62, 2006 Boudiaf M et al: Small-bowel diseases: prospective evaluation of multidetector row helical CT enteroclysis in 107 consecutive patients. Radiology. 233(2):338-44, 2004

Celiac-Sprue Disease Small Intestine

(Left) Axial CT in a 69-year-old woman with chronic diarrhea & pain shows fluid distention of the SB with conformation of the flaccid segments. The fold pattern of the jejunum is blunted. (Right) Axial CT in the same patient shows a short segment, nonobstructing intussusception with a "target" appearance and intraluminal mesenteric fat. The fold pattern of the ileum is more prominent than that of the jejunum, a reversal of the normal situation. Biopsy & response to a gluten-free diet confirmed the diagnosis of celiac disease.

(Left) Films from a barium SBFT in a 30-year-old woman with steatorrhea show a typical malabsorption pattern, consisting of dilution of the barium and dilation of the lumen. The folds within the jejunum appear blunted. There is poor coating of the mucosa by the barium. (Right) SBFT in the same patient illustrates intermittent intussusception, with a coiled "spring" appearance in the mid jejunum . Celiac disease is the most common specific cause of malabsorption.

(Left) Axial CECT in a patient with sprue shows fluiddistended bowel. One segment of jejunum has focal thickening of the wall, which was found to be due to lymphoma. (Right) Axial CECT in the same patient shows multifocal gastric wall thickening , which was also due to lymphoma. Patients with refractory sprue are at increased risk for both lymphoma and carcinoma of the bowel.

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Small Intestine

Whipple Disease KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Rare systemic disease caused by Tropheryma whipplei infection leading to multiple systemic manifestations, including chronic diarrhea and malabsorption

• Celiac disease • Intestinal opportunistic infections • Intestinal metastases and lymphoma

IMAGING

PATHOLOGY

• Fluoroscopic small bowel follow-through or enteroclysis ○ Distal duodenum and jejunum are most often involved, with distal small bowel/ileum involved in severe cases ○ Thickened, irregular folds with sand-like micronodules ○ Small bowel lumen may be normal or mildly dilated • CT ○ Low-density enlarged mesenteric and retroperitoneal lymph nodes that may have near fat-density ○ Thickened proximal small bowel folds ± submucosal edema due to hypoalbuminemia • MR ○ Lymph nodes may show T1 signal due to fat

• Caused by Tropheryma whipplei (probably orally acquired) • Not all patients with Tropheryma whipplei infection develop Whipple disease, and underlying autoimmune disorders or genetic abnormalities may potentiate clinical syndrome

(Left) Small bowel followthrough shows nodular thickening of the jejunal folds in a patient with Whipple disease. (Right) Axial CECT shows jejunal fold thickening , as well as low-attenuation mesenteric and periaortic lymphadenopathy . Endoscopic biopsy of the jejunal mucosa confirmed PASpositive macrophages containing gram-negative, acid-fast bacilli, characteristic of Whipple disease.

(Left) Small bowel followthrough in a 40-year-old man with arthralgias and diarrhea demonstrates thickened, nodular jejunal folds. (Right) Axial CECT in the same patient shows marked thickening of the small bowel with retroperitoneal and mesenteric lymphadenopathy , which appears lower in attenuation than in most other causes of adenopathy. Endoscopic biopsy of the jejunal mucosa revealed villi distended with macrophages full of periodic acid-Schiffpositive bacilli, diagnostic of Whipple disease.

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CLINICAL ISSUES • Mostly affects middle-aged Caucasian men • Prodromal phase: Fevers, fatigue, arthralgias, arthritis • Late phase: Diarrhea, malabsorption, steatorrhea, adenopathy, abdominal pain ○ GI symptoms generally later manifestation of disease • Can be fatal without therapy (long-term antibiotics) • Clinical symptoms often subside quickly after therapy

Mastocytosis

IMAGING • Cutaneous mastocytosis: (Urticaria pigmentosa) is most common form • Systemic mastocytosis: Mast cell proliferation in skin, bones, lymph nodes, and abdominal viscera • Gastrointestinal tract involved in 16% of cases ○ Peptic ulcer disease and malabsorption ○ Duodenum and SB: Thick folds, fast transit ○ Mucosal nodularity (2-3 mm sand-like nodules) – Fluid-distended lumen of SB • Hepatomegaly (40% of adult cases) • Biliary tree: Infiltration of walls; irregular strictures • Splenomegaly with nodular deposits (50% of cases) • Lymphadenopathy; thickened omentum and mesentery • Sclerotic &/or lytic lesions in axial skeleton • Bone scan: Lytic lesions, osteoporosis or osteosclerosis

• • • •

Zollinger-Ellison syndrome Celiac-sprue disease Malabsorption conditions Primary sclerosing cholangitis (for biliary involvement)

Small Intestine

KEY FACTS

PATHOLOGY • Systemic mastocytosis is one of the myeloproliferative neoplastic conditions ○ Along with polycythemia, myelofibrosis, CML, etc.

CLINICAL ISSUES • Complications ○ Hematologic malignant transformation rate is 30% • Treatment: Epinephrine, steroids, H1 and H2 antagonists, proton-pump inhibitors, anticholinergics, chemotherapy ○ Hematopoietic stem cell transplant shows promise

TOP DIFFERENTIAL DIAGNOSES • Carcinoid tumor

(Left) Axial NECT in an elderly man with diarrhea and abnormal liver function shows diffuse sclerotic lesions throughout the axial skeleton. Note the irregular, moderate dilation of the intrahepatic bile ducts and splenomegaly. (Right) Axial NECT in the same patient shows fluid distention and wall thickening of the SB . This patient had biopsy-proven bile duct wall infiltration and bowel with excessive mast cells, essentially diagnostic of systemic mastocytosis.

(Left) CT in the same patient with systemic mastocytosis shows diffuse sclerotic lesions throughout the axial skeleton, along with fluiddistended SB with thickened walls . (Right) Film from small bowel follow-through in a patient with proven mastocytosis shows diffuse abnormalities of the small intestine, including effacement of the normal fold pattern and replacement with a nodular pattern.

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Small Intestine

Crohn Disease KEY FACTS

TERMINOLOGY • Disease of unknown etiology characterized by transmural inflammation of GI tract

IMAGING • CT and MR enterography have supplanted most barium studies for diagnosis in adults and children ○ Faster to perform, less operator dependent, more sensitive and specific ○ Allow assessment of extraintestinal disease • Noncicatrizing, acute phase ○ Target or double halo sign ○ Hyperenhancing inner ring (mucosa) ○ Low-density middle ring (submucosal edema) ○ Engorged vasa recta: Comb sign ○ Proliferation of mesenteric fat and lymphadenopathy • Chronic or cicatrizing phase ○ Strictures, ± dilated small bowel (SB) upstream ○ Abscesses, fistulas, sinus tracts

(Left) This graphic in the sagittal plane illustrates typical features of Crohn disease including, segmental small bowel (SB) wall thickening, mucosal hyperemia , transmural inflammation with deep ulcers , mesenteric vessel engorgement, and fibrofatty proliferation . (Right) This 19-year-old man has an acute flare of his Crohn disease. CT shows mucosal hyperenhancement, wall thickening, and luminal narrowing of the terminal ileum (TI) .

(Left) CT in the same patient shows the inflamed TI , as well as local mesenteric fibrofatty proliferation and engorged vasa recta . (Right) A spot film from a SBFT in the same patient shows diseased TI and colon with longitudinal and transverse ulcerations of the ileal mucosa (cobblestone pattern) and luminal narrowing. At least 2 sinus tracts are opacified. Traditional barium studies remain valuable for evaluation of strictures, fistulas, and sinus tracts.

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• Barium enema, enteroclysis can depict strictures & fistulas • Colonoscopy is best to assess colonic involvement, guide biopsy of colon and terminal ileum • Capsule endoscopy may complement imaging studies ○ Not of proven value following negative CT or MR enterography

TOP DIFFERENTIAL DIAGNOSES • Ulcerative colitis ("backwash" ileitis) • Mesenteric enteritis and adenitis • Infectious ileitis or colitis

PATHOLOGY • Transmural inflammation, lymphoid aggregates, noncaseating granulomas ○ Predisposes to strictures, fistulas, sinus tracts, abscesses

CLINICAL ISSUES • Crohn disease is characterized by intermittent periods of exacerbation of symptoms followed by remissions

Crohn Disease

Synonyms • Terminal ileitis, regional enteritis, ileocolitis

Definitions • Disease of unknown etiology characterized by transmural inflammation of GI tract

IMAGING General Features • Best diagnostic clue ○ Segmental, discontinuous inflammation of small bowel (SB) ± colon with mucosal hyperenhancement, submucosal edema, engorged vasa recta – Usually accompanied by clusters of prominent mesenteric nodes • Location ○ Anywhere along GI tract, from mouth to anus – Most common: Terminal ileum (TI) and proximal colon ○ Distribution – 80% of patients have SB involvement – 50% have ileocolitis – 20% have disease limited to colon □ Only 10% have rectal involvement • Morphology ○ Transmural inflammation – Predisposes to strictures, fistulas, sinus tracts, abscesses ○ Skip lesions (segmental or discontinuous)

– Nodes rarely more than 1 cm in diameter • Chronic or cicatrizing phase ○ Luminal narrowing, ± dilated SB upstream ○ Mural stratification lost: Indistinct mucosa, submucosa, muscularis propria – Alternatively, submucosal fat may proliferate, preserve stratification ○ Abscesses, fistulas, sinus tracts – Fistulas connect 2 epithelialized surfaces (e.g., bowelto-bowel, bladder, vagina, or skin) – Sinus tracts are blind-ending (e.g., bowel to abscess) ○ Mesenteric changes: Abscess, fibrofatty proliferation, mildly enlarged nodes ○ Perianal disease: Fistulas and sinus tracts

MR Findings • Breath-holding, fat suppression, and gadolinium enhancement show extent and severity of inflammation ○ Mucosal hyperenhancement, submucosal edema, engorged vasa recta in acute inflammation • Allows real-time imaging to assess peristalsis in segments of suspected disease • Sensitive in detecting and characterizing fistulas, sinuses, abscesses in perianal Crohn disease • Diffusion-weighted imaging can reveal active inflammation even without IV contrast administration

Ultrasonographic Findings • Grayscale ultrasound ○ Transrectal sonography – Mural thickening, abscesses, fistulas

Fluoroscopic Findings

Other Modality Findings

• Barium studies: Early changes ○ "Target" or bull's-eye appearance of aphthoid ulcerations: Punctate shallow central barium collections surrounded by halo of edema ○ "Cobblestoning": Combination of longitudinal and transverse ulcers ○ Deep fissuring ulcers • Barium studies: Late changes ○ Skip lesions: Segmental disease with normal intervening segments ○ Sacculations seen on antimesenteric border ○ Postinflammatory pseudopolyps, haustral loss, intramural abscess ○ String sign: Luminal narrowing and ileal stricture ○ Sinus tracts, fissures, fistulas are hallmarks of disease ○ Anorectal lesions: Ulcers, fissures, abscesses, hemorrhoids, stenosis

• Colonoscopy is best modality to assess colon ○ Often allows inspection and biopsy of terminal ileum • Capsule endoscopy is commonly used to complement imaging studies ○ Not of proven value following "negative" CT or MR ○ Contraindicated in patients with enteric strictures

CT Findings • Noncicatrizing, acute phase ○ Stratified wall thickening of discontinuous SB segments – Target or double halo sign – Hyperenhancing inner ring (mucosa) – Low-density middle ring (submucosal edema) – Soft tissue density outer ring (muscularis propria and serosa) ○ Comb sign: Engorged vasa recta – Supply actively inflamed SB segments ○ Proliferation of mesenteric fat and lymphadenopathy

Small Intestine

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Multiplanar CT or MR enterography – Distend bowel with water ± neutral contrast agent (e.g., VoLumen) – Bolus IV contrast medium at 3-4 mL/sec – For CT, use low-dose protocols (e.g., iterative reconstruction) to reduce radiation risk ○ Barium enema, enteroclysis – Can be useful for depiction of strictures and fistulas ○ MR for perianal and rectal Crohn disease

DIFFERENTIAL DIAGNOSIS Ulcerative Colitis ("Backwash" Ileitis) • Lesions are usually continuous and almost always involve rectum ○ Terminal ileal pathology in < 25% of cases • Generally not transmural process ○ Fistulas, abscesses, strictures are much less common • Some 10-15% of patients have "indeterminate colitis" ○ Features of Crohn disease and ulcerative colitis overlap 371

Small Intestine

Crohn Disease

Mesenteric Enteritis and Adenitis

Demographics

• Common cause of RLQ pain in children, adolescents • Enlarged mesenteric nodes, ileal wall thickening • Usually resolves spontaneously in 2-4 days

• Age ○ Age: 15-25 years (small peak at 50-80 years) • Ethnicity ○ More common in Caucasian and Jewish populations • Epidemiology ○ 4x increased incidence with smoking

Infectious Ileitis or Colitis • Opportunistic infections: Mycobacterial, cryptosporidiosis, Cytomegalovirus (CMV) • Mycobacterium tuberculosis ○ Ileocecal (most common): Transmural, stenosis, fistulas • Cryptosporidiosis ○ Most common cause of enteritis in AIDS patients ○ Thickening of folds and bowel wall; fluid in lumen • CMV ○ Terminal ileitis indistinguishable from Crohn

Radiation Enteritis • • • •

Due to therapeutic or excessive abdominal irradiation Usually pelvic SB segments and rectum Bowel wall thickening, luminal narrowing ± strictures, sinuses, fistulas simulating Crohn disease

Natural History & Prognosis • Complications: Fistulas, sinus tracts, toxic megacolon, obstruction, perforation • Prognosis ○ Crohn disease is characterized by intermittent periods of exacerbation of symptoms followed by remissions ○ 10-20% lead symptom-free lives after 1st presentation ○ > 50% develop strictures &/or penetrating disease (e.g., abscess or fistula) within 10 years of onset ○ 30-53% recurrence after surgical resection, usually proximal side of anastomosis • Disease itself and treatment predispose to lymphoma in bowel

Lymphoma

Treatment

• Non-Hodgkin lymphoma more common in GI tract ○ Nodular, polypoid, infiltrating masses ○ Focally infiltrating form of terminal ileum – "Aneurysmal dilation" of lumen – Sausage-shaped soft tissue density thickening of bowel wall ○ Large (> 1 cm) mesenteric and retroperitoneal nodes

• Endoscopic biopsy to diagnose • Medical ○ Steroids, azathioprine, mesalamine ○ Metronidazole, antibody treatment ○ Biological agents and immunomodulator therapy (e.g., anti-TNF) – Effective at controlling Crohn but predispose to opportunistic infections • Surgical ○ Resection of diseased bowel, strictures, fistulas

PATHOLOGY General Features • Etiology ○ Exact etiology unknown; possible factors – Immunologic: Antibody and cell-mediated types – Nutritional, hormonal, vascular – Genetic, environmental, infectious, psychologic • Genetics ○ Familial disposition ○ Common in monozygotic twins and siblings ○ Polygenic inheritance pattern • Associated abnormalities ○ Arthritis, gallstones, sclerosing cholangitis, uveitis, ankylosing spondylitis, arterial and venous thrombosis

DIAGNOSTIC CHECKLIST Consider • Associated findings (e.g., cholangitis, arthritis)

SELECTED REFERENCES 1. 2. 3.

4.

Gross Pathologic & Surgical Features • Skip lesions are common • Edema, inflammation, fibrosis, luminal narrowing • Adhesions, fistulas, fissures, strictures

Microscopic Features • Transmural inflammation, lymphoid aggregates, noncaseating granulomas

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Diarrhea, pain, melena, weight loss, fever ○ Malabsorption; fissures and fistulas (perianal area) 372

5.

Allen BC et al: MR enterography for assessment and management of small bowel Crohn disease. Radiol Clin North Am. 52(4):799-810, 2014 Mandel MD et al: Have biologics changed the natural history of Crohn's disease? Dig Dis. 32(4):351-9, 2014 Marineaţă A et al: Extra intestinal manifestations and complications in inflammatory bowel disease. Rev Med Chir Soc Med Nat Iasi. 118(2):279-88, 2014 Qiu Y et al: Systematic review with meta-analysis: magnetic resonance enterography vs. computed tomography enterography for evaluating disease activity in small bowel Crohn's disease. Aliment Pharmacol Ther. 40(2):134-46, 2014 Rodriguez P et al: Imaging Crohn disease: MR enterography. J Comput Assist Tomogr. 38(2):219-27, 2014

Crohn Disease Small Intestine

(Left) This 37-year-old man has chronic and acute symptoms of abdominal pain and diarrhea. CT shows distention of some proximal jejunal segments . (Right) CT in the same patient shows a more distal segment of SB with hyperenhancement of the mucosa and submucosal edema , along with clusters of mildly enlarged mesenteric nodes .

(Left) CT in the same patient shows 2 segments of inflamed SB that were separated by normal segments of bowel, the classic "skip lesions" of Crohn disease. Note the engorged vasa recta supplying the more distal segment of inflamed bowel. (Right) CT in the same patient shows additional segments of inflamed bowel with mucosal enhancement, wall thickening, and luminal narrowing.

(Left) Coronal reformatted CT in the same patient shows separate segments of inflamed bowel along with mesenteric lymphadenopathy and prominent vessels. (Right) Coronal CT in the same patient shows inflamed bowel and mesenteric lymphadenopathy . The diagnosis of Crohn disease was confirmed on colonoscopy with biopsy of the terminal ileum.

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Small Intestine

Crohn Disease

(Left) This patient had prior ileocecal resection for CD and has recurrent symptoms. Coronal T2WI MR shows mural thickening of a SB segment representing the neoterminal ileum, where recurrent disease often occurs. (Right) Coronal T1 C+ FS MR in the same patient shows vivid mucosal enhancement of the affected segment . The adjacent small bowel and colon do not enhance with the same intensity.

(Left) This 52-year-old woman has chronic Crohn colitis with recent recurrent urinary tract infections. CT shows markedly inflamed sigmoid colon and mesentery. (Right) CT in the same patient shows an extraluminal collection of gas and fluid interposed between the colon, uterus , and top of the bladder .

(Left) CT in the same patient shows a markedly thickened wall of bladder along with gas and debris within the bladder. (Right) Retrograde injection of contrast material into the bladder opacifies the sigmoid colon through a fistulous tract . Fistulas are a key feature of the transmural inflammation caused by Crohn disease.

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Crohn Disease Small Intestine

(Left) Film from a SBFT in a 26-year-old woman with chronic Crohn disease shows severe SB strictures, fistulas , and ulceration with skip areas . (Right) Spot film from a SBFT in a 37-year-old patient with known Crohn disease shows the string sign, a severe luminal narrowing of the terminal ileum and the ascending colon. Note the sinus tract and indirect evidence of mesenteric fibrofatty proliferation separating the TI from other bowel segments.

(Left) Axial CECT in a 48-yearold woman presenting with recent weight loss and diarrhea shows segmental small bowel wall thickening characterized by excessive submucosal fat deposition , indicative of chronic inflammation. The nonepithelialized fistulas extend from 1 bowel segment to the others. (Right) Coronal CECT in the same patient again demonstrates the extension of the nonepithelialized fistulas between the bowel segments.

(Left) This man has chronic, recurrent CD but has new symptoms of weight loss and fever. Coronal CT shows a short segment of actively inflamed SB with enhancing mucosa and submucosal edema. (Right) CT in the same patient shows a separate segment of SB that has sausage-like, soft tissue density wall thickening felt to be concerning for neoplasm. Surgical resection confirmed lymphoma of the SB, a rare but recognized complication of CD or its medical therapy (steroids and immunomodulator drugs).

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Small Intestine

Intestinal Scleroderma KEY FACTS

TERMINOLOGY • Progressive systemic sclerosis

IMAGING • Multisystemic disorder with immunologic and inflammatory changes • Characterized by atrophy, fibrosis, sclerosis of skin, vessels, and organs ○ Smooth muscle is replaced by fibrous tissue • Gastrointestinal tract: Most common internal organ system involvement (80-90%) ○ Esophagus > duodenum > anorectal > small bowel > colon • Small bowel ○ Marked dilatation of small bowel, especially duodenum and jejunum ○ Duodenal findings identical to SMA syndrome ○ "Hidebound" small bowel: Atonic with closely spaced thin folds, sacculations (pathognomonic of scleroderma)

(Left) This 50-year-old man has diffuse scleroderma with progressive dysphagia & abdominal bloating. A film from the upper GI small bowel follow-through (SBFT) shows a dilated, atonic esophagus that is slow to empty due to a distal esophageal, peptic stricture . (Right) A 90minute film (same case & study) from SBFT shows classic scleroderma of the small bowel with dilated, atonic jejunum & closely spaced, thin transverse folds with slow transit. "Pseudo-obstruction" is another descriptive term relevant to this case.

(Left) Axial CECT in a 40-yearold woman demonstrates closely packed, thin small bowel folds and diffusely dilated lumen, classic features of scleroderma with pseudoobstruction. (Right) Coronal CECT in the same patient demonstrates the dilated small bowel with a "hidebound" appearance of closely packed, thin folds (particularly in the jejunum), a characteristic feature of scleroderma. Also note the disproportionate dilation of the duodenum , another common feature of scleroderma.

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○ Prolonged transit time with barium retention in duodenum and small bowel up to 24 hours ○ ± pneumatosis intestinalis and pneumoperitoneum ○ ± transient, nonobstructive intussusceptions • Colon ○ Sacculations on border of transverse and descending colon ○ Loss of haustrations ○ Stercoral ulceration (from retained fecal material in rectosigmoid)

TOP DIFFERENTIAL DIAGNOSES • SMA syndrome • Celiac-sprue disease • Ileus

DIAGNOSTIC CHECKLIST • Markedly dilated atonic small bowel with thin, crowded circular folds and delayed barium transit time

Intestinal Scleroderma

Synonyms • Progressive systemic sclerosis

Definitions • Multisystem disorder of small vessels and connective tissue of unknown etiology

IMAGING General Features • Best diagnostic clue ○ Dilated, atonic small bowel with crowded folds and widemouthed sacculations • Other general features ○ Multisystemic disorder with immunologic and inflammatory changes ○ Characterized by atrophy, fibrosis, sclerosis of skin, vessels, and organs ○ Involves skin and parenchyma of multiple organs – GI tract, lungs, heart, kidneys, and nervous system ○ Gastrointestinal tract (GI) scleroderma – 2nd most common manifestation after skin changes (80-90% of patients) – Most common sites: Esophagus > duodenum > anorectal > small bowel > colon – Most frequent cause of chronic intestinal pseudoobstruction ○ Scleroderma classified into 2 types – Diffuse scleroderma – CREST syndrome (more benign course) ○ Diffuse scleroderma: Cutaneous and visceral involvement – Severe interstitial pulmonary fibrosis – Organ failure more likely – Associated with antitopoisomerase I antibody (anti-Scl 70) ○ CREST syndrome: Less cutaneous and visceral involvement – Calcinosis of skin – Raynaud phenomenon – Esophageal dysmotility – Sclerodactyly – Telangiectasia

Radiographic Findings • Esophagram ○ Atony, aperistalsis: Lower 2/3 of esophagus (smooth muscle) ○ Mild to moderate dilation of esophagus ○ Patulous lower esophageal sphincter: Early finding ○ Ulcers, fusiform peptic stricture (reflux esophagitis) – Reflux predisposes to Barrett metaplasia (present in 40%) ○ Hiatal hernia • Upper GI series ○ Stomach: Gastric dilation and delayed emptying • Small bowel follow-through ○ Marked dilatation of small bowel (particularly 2nd and 3rd parts of duodenum and jejunum)

– May have "megaduodenum": Dilation made worse by compression of 3rd portion as it passes under mesenteric vessels – Imaging findings identical to SMA syndrome ○ Pathognomonic: Hidebound sign of small bowel – Dilated jejunal lumen with crowded, thin circular folds – Seen in > 60% of cases of scleroderma-related pseudo-obstruction – Due to muscle atrophy and uneven replacement by collagen in longitudinal fibers, with intense fibrosis of submucosa ○ Wide-mouthed sacculations (true diverticula) ○ Prolonged transit time with barium retention in duodenum and small bowel up to 24 hours ○ ± pneumatosis intestinalis and pneumoperitoneum – May result from steroid medications + effect of dilated bowel ○ ± transient, nonobstructive intussusceptions • Barium enema ○ Sacculations on border of transverse and descending colon ○ Marked dilatation (may simulate Hirschsprung disease) ○ Chronic phase: Complete loss of haustrations – Simulates cathartic colon or chronic ulcerative colitis ○ Stercoral ulceration (from retained fecal material in rectosigmoid)

Small Intestine

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Superior Mesenteric Artery (SMA) Syndrome • Narrowing of angle between SMA and aorta may compress 3rd part of duodenum causing proximal dilatation ○ Usually seen in asthenic persons who rapidly lose weight and retroperitoneal fat ○ Due to prolonged bed rest or immobilization – e.g., patients with whole body burns, body casts, spinal injury or surgery • Upper GI findings ○ Marked dilatation of 1st and 2nd parts of duodenum ○ Vertical, linear, extrinsic, band-like defect in transverse part of duodenum overlying spine ○ Obstruction is partially relieved in prone position • CT may demonstrate beak-like compression of 3rd part of duodenum between SMA and aorta • Scleroderma patients are thin; SMA compression may contribute to duodenal dilation

Celiac-Sprue Disease • • • •

Gluten-sensitive enteropathy Segmental dilatation of small intestine Excess fluid in lumen (flocculation of barium) Atrophic duodenal and jejunal folds; relative hypertrophy of ileal folds • Transient intussusceptions

Ileus • Diffusely dilated lumen of bowel ○ May have inflammatory component (e.g., acute pancreatitis) • Small bowel folds in ileus usually normal to thick, rather than thin and crowded in scleroderma 377

Small Intestine

Intestinal Scleroderma

PATHOLOGY General Features • Etiology ○ Unknown; autoimmune with genetic predisposition ○ May be initiated by environmental antigens like silica and L-tryptophan ○ Immunologic mechanism (delayed hypersensitivity reaction) – production of cytokines (TNF- or IL-1) increased collagen production – Vascular damage and activation of fibroblasts • Genetics ○ Diffuse: Antitopoisomerase I antibodies associated with HLA-DR5 ○ Localized: Anticentromere antibodies associated with HLA-DR 1, 4, and 5 • Associated abnormalities ○ May be associated with systemic lupus erythematosus, polymyositis, dermatomyositis ○ Small bowel stasis may facilitate bacterial overgrowth – May exacerbate anemia and malnutrition

• Ethnicity ○ African Americans > Caucasians • Epidemiology ○ Incidence: 14.1/1,000,000 ○ Prevalence: 19-75/100,000 persons

Natural History & Prognosis • Complications ○ Barrett esophagus adenocarcinoma ○ Bowel pseudo-obstruction • Prognosis ○ Limited disease with antinuclear antibodies (ANA): Good prognosis ○ Diffuse disease: Poor with involvement of kidneys, heart, and lungs ± GI tract

Treatment • • • • •

Small frequent meals; elevation of head of bed Avoid tea and coffee Cimetidine, ranitidine, omeprazole Metoclopramide, laxatives Patients with severe malabsorption ○ Parenteral hyperalimentation

Gross Pathologic & Surgical Features • Rubber-hose inflexibility: Lower 2/3 of esophagus • Thin and ulcerated mucosa • Dilated gas and fluid-containing SB loops with sacculations

Microscopic Features • Perivascular lymphocytic infiltrates • Early capillary and arteriolar injury • Atrophy and fragmentation of smooth muscle deposition and fibrosis

collagen

Presentation • Most common signs/symptoms ○ Esophagus – Dysphagia, regurgitation – Epigastric fullness and burning pain ○ Duodenum – Nausea, early satiety ○ Small bowel – Bloating, abdominal pain – Weight loss, diarrhea, anemia ○ Colon – Chronic constipation ○ Rectum and anus – Fecal incontinence – Fecal impaction; stercoral ulceration • Laboratory data ○ Increased erythrocyte sedimentation rate (ESR) ○ Iron, B12, and folic acid deficiency anemias ○ Increased antinuclear antibodies (ANA) • Age ○ Onset at 30-50 years • Gender ○ M:F = 1:3 378

Consider • Check for involvement of other organs • Check for family history of collagen vascular diseases

Image Interpretation Pearls

CLINICAL ISSUES

Demographics

DIAGNOSTIC CHECKLIST

• Markedly dilated atonic small bowel with thin, crowded circular folds and delayed barium transit time

SELECTED REFERENCES 1.

Savarino E et al: Gastrointestinal involvement in systemic sclerosis. Presse Med. 43(10 Pt 2):e279-91, 2014 2. Zapatier JA et al: Intestinal obstruction and pseudo-obstruction in patients with systemic sclerosis. Acta Gastroenterol Latinoam. 43(3):227-30, 2013 3. Balbir-Gurman A et al: Pneumatosis cystoides intestinalis in sclerodermarelated conditions. Intern Med J. 42(3):323-9, 2012 4. Ohkubo H et al: An epidemiologic survey of chronic intestinal pseudoobstruction and evaluation of the newly proposed diagnostic criteria. Digestion. 86(1):12-9, 2012 5. Forbes A et al: Gastrointestinal complications: the most frequent internal complications of systemic sclerosis. Rheumatology (Oxford). 48 Suppl 3:iii369, 2009 6. Koh CE et al: The internal anal sphincter in systemic sclerosis. Dis Colon Rectum. 52(2):315-8, 2009 7. Domsic R et al: Gastrointestinal manifestations of systemic sclerosis. Dig Dis Sci. 53(5):1163-74, 2008 8. Parodi A et al: Small intestinal bacterial overgrowth in patients suffering from scleroderma: clinical effectiveness of its eradication. Am J Gastroenterol. 103(5):1257-62, 2008 9. Gregersen H et al: A new method for evaluation of intestinal muscle contraction properties: studies in normal subjects and in patients with systemic sclerosis. Neurogastroenterol Motil. 19(1):11-9, 2007 10. Kudoh K et al: Gastrojejunostomy and duodenojejunostomy for megaduodenum in systemic sclerosis sine scleroderma: report of a case. Dig Dis Sci. 52(9):2257-60, 2007 11. Lock G et al: Gastrointestinal manifestations of progressive systemic sclerosis. Am J Gastroenterol. 92(5):763-71, 1997

Intestinal Scleroderma Small Intestine

(Left) Film from a SBFT shows dilation of the duodenum with an abrupt narrowing as it crosses the spine. (Right) Delayed SBFT film from the same patient shows barium within the colon, which has a peculiar appearance of sacculations along the mesenteric border. These reflect the muscle atrophy within the bowel wall and its replacement by collagen and fibrosis.

(Left) Film from a SMFT in a 25-year-old man with scleroderma shows marked dilation of the duodenum with abrupt narrowing as it crosses the spine. The transverse folds of the jejunum are thin and abnormally close together. (Right) In the same case, a delayed film from a SBFT shows barium in the colon but persistent dilation of the duodenum.

(Left) Spot film from a SBFT shows sacculation and abnormal folds in the small bowel. (Right) Barium enema shows sacculation of the transverse colon and loss of a normal haustral pattern throughout most of the colon, all due to scleroderma.

379

Small Intestine

Intestinal (Angioneurotic) Angioedema KEY FACTS

TERMINOLOGY

PATHOLOGY

• Noninflammatory transient edema of intestinal wall due to vascular permeability and extravasation of intravascular fluid

• Hereditary angioedema: Autosomal dominant ○ C1-INH (C1 esterase) deficiency • Acquired C1-INH deficiency: Associated with hepatitis, lymphoproliferative, neoplastic, and autoimmune disorders • Allergic angioedema ○ Angioedema secondary to medication (ACE inhibitors, aspirin, iodinated contrast)

IMAGING • Ascites (100% of cases), small to moderate volume • Bowel wall thickening: Submucosal edema, mucosal and mesenteric hyperemia ○ Involves long segment of jejunum &/or ileum • Luminal dilation (> 2.5 cm) without obstruction • Imaging findings are entirely reversible, seen only during acute phase

TOP DIFFERENTIAL DIAGNOSES • Vasculitis • Ischemic enteritis • Intestinal trauma

(Left) This 21-year-old woman with hereditary angioedema had multiple episodes of laryngeal edema and abdominal pain. Coronal CECT, taken during one acute episode, shows striking submucosal edema within the walls of the right colon distal small bowel, along with ascites. (Right) Axial CECT, in this case of acquired angioedema due to hepatitis, shows long segmental jejunal thickening and ascites . Laboratory tests confirmed C1 esterase deficiency and complement activation.

(Left) This elderly woman has hypertensive heart disease and presents with acute abdominal pain. Axial CECT shows a long segment of small bowel wall thickening and submucosal edema with associated ascites . (Right) Coronal CECT from the same case shows the long segment bowel wall edema , mesenteric edema , and ascites . Intestinal angioedema was attributed to the patient's ACE-inhibitor medication, which was withheld; symptoms resolved within 36 hours.

380

CLINICAL ISSUES • Abdominal pain, vomiting, laryngeal and cutaneous edema • Predominance in women and blacks for ACE-inhibitorrelated intestinal angioedema • Many patients are not diagnosed & undergo laparotomy • 40 million patients take ACE-inhibitor medication to control hypertension (e.g., lisinopril, enalapril) ○ ~ 0.5% of these will develop intestinal angioedema (200,000) ○ Almost all radiologists will encounter this disorder

Intestinal (Angioneurotic) Angioedema

Definitions • Noninflammatory transient edema of intestinal wall due to vascular permeability and extravasation of intravascular fluid

IMAGING General Features • Best diagnostic clue ○ Long segmental intestinal wall thickening with ascites

CT Findings • Ascites (100% of cases), small to moderate volume • Bowel wall thickening: Submucosal edema, mucosal and mesenteric hyperemia ○ Involves long segment of jejunum (> ileum > duodenum > colon) • Luminal dilation (> 2.5 cm) without obstruction • Imaging findings are entirely reversible, seen only during acute phase

DIFFERENTIAL DIAGNOSIS Vasculitis • Imaging findings essentially identical to angioedema

Ischemic Enteritis

Gross Pathologic & Surgical Features • Edematous bowel wall, patchy reddish discoloration, serous fluid in peritoneal cavity

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, vomiting, laryngeal and cutaneous edema ○ 75% of patients presenting with cutaneous angioedema have abdominal complaints • Clinical profile ○ serum levels of C1-INH and C4 in hereditary angioedema ○ C1 esterase, but normal complement proteins in ACEinhibitor-related angioedema

Demographics • Gender ○ Predominance in women and blacks for ACE-inhibitorrelated intestinal angioedema • Epidemiology ○ 40 million patients take ACE-inhibitor medication to control hypertension (e.g., lisinopril, enalapril) ○ ~ 0.5% of these will develop intestinal angioedema (200,000) – Almost all radiologists will encounter this disorder

• Older patient, fever, leukocytosis, acidosis

Natural History & Prognosis

Intestinal Trauma

• Patients with hereditary, acquired, and ACE-inhibitorrelated type have frequent episodes of attacks, each lasting for 1-3 days ○ Many patients are not diagnosed & undergo laparotomy • Most patients with ACE inhibitor-related-angioedema develop symptoms within 24-48 hours of starting drug

• Look for history of blunt trauma, anticoagulation, or hemophilia

PATHOLOGY General Features • Etiology ○ Hereditary angioedema: Autosomal dominant – Deficiency of C1 esterase inhibitor protein (C1-INH) ○ Acquired C1-INH deficiency: Associated with hepatitis, lymphoproliferative, neoplastic, and autoimmune disorders ○ Allergic angioedema – Angioedema secondary to medication (angiotensinconverting [ACE] inhibitors, aspirin, iodinated contrast) ○ Idiopathic angioedema • Associated abnormalities ○ Cutaneous angioedema, laryngeal edema • Mechanism ○ Plasma bradykinin level rises during acute attacks – Bradykinin is potent activator of nitric oxide system causing vasodilation and vascular permeability □ C1-INH deficiency upregulation of complement cascade bradykinin pathway activation bradykinin □ ACE inhibitor angiotensin 2 level bradykinin ○ Causes rapid onset of local increased permeability of capillary bed local plasma extravasation

Small Intestine

TERMINOLOGY

Treatment • Hereditary angioedema ○ Danazol: Increases serum concentration of C1-INH (prophylaxis) • Allergic angioedema ○ Epinephrine, antihistamine, corticosteroid • ACE-inhibitor-related angioedema ○ Discontinue ACE inhibitor ○ Supportive management

DIAGNOSTIC CHECKLIST Consider • Be prepared for concomitant laryngeal edema • Look for family history or previous episodes • Look for recent administration of ACE inhibitor

SELECTED REFERENCES 1. 2. 3.

Mutnuri S et al: Visceral angioedema: an under-recognized complication of angiotensin-converting enzyme inhibitors. Postgrad Med. 1-3, 2015 Gakhal MS et al: Hereditary angioedema: imaging manifestations and clinical management. Emerg Radiol. ePub, 2014 Scheirey CD et al: Angiotensin-converting enzyme inhibitor-induced smallbowel angioedema: clinical and imaging findings in 20 patients. AJR Am J Roentgenol. 197(2):393-8, 2011

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Small Intestine

Small Bowel NSAID Stricture KEY FACTS

TERMINOLOGY • Focal strictures in small bowel (SB) secondary to NSAID use

IMAGING • Barium SBFT or enteroclysis ○ Multiple short-segment annular strictures ± partial SB obstruction ○ Strictures may resemble normal plicae circulares on enteroclysis • CT findings ○ Strictures: Short segmental narrowing of lumen with dilation of bowel upstream ○ Mucosal inflammation: Mucosal hyperenhancement and submucosal edema • Capsule endoscopy can confirm diagnosis

TOP DIFFERENTIAL DIAGNOSES • Crohn disease ○ Longer segments of transmural involvement

(Left) Axial NECT in a 40-yearold man shows a dilated proximal, mid small bowel and collapsed colon. (Right) Axial NECT in the same patient shows an abrupt transition from dilated to collapsed small bowel in the ileum . There was no history of prior abdominal surgery, making adhesive bowel obstruction a less likely etiology.

(Left) Small bowel followthrough in the same patient shows dilation of the proximal small bowel and a short stricture in the ileum with collapsed bowel distal to this point. (Right) Spot film from the small bowel study in the same patient shows a short stricture in the ileum. At surgery, the stricture was confirmed, resected, and determined to be due to injury from chronic use of NSAIDs.

382

• Celiac-sprue disease ○ Jejunoileal fold pattern reversal • Ischemic enteritis ○ Bowel wall thickening; strictures can be late result • Radiation enteritis ○ Longer strictures; pelvic SB segments • Small intestine vasculitis ○ Long segments of submucosal edema

PATHOLOGY • All NSAID (including aspirin) formulations can cause enterocolitis ○ Slow-release formulations affect distal SB and colon

CLINICAL ISSUES • Often asymptomatic; may have symptoms of bowel obstruction • May require surgery or endoscopic balloon dilation for bowel obstruction

Small Bowel NSAID Stricture

Abbreviations • Nonsteroidal anti-inflammatory drugs (NSAIDs)

Ischemic Enteritis

Synonyms

• Occlusion of superior mesenteric artery or vein • Bowel wall thickening; strictures can be late result

• Diaphragm disease

Radiation Enteritis

Definitions

• Pelvic SB segments affected most often • Mural thickening and luminal narrowing • Single or multiple strictures of varying length

• Focal strictures in small bowel (SB) secondary to NSAID use

IMAGING General Features • Best diagnostic clue ○ Multiple short-segment annular strictures ± partial SB obstruction • Location ○ Middle and distal small bowel ○ May also be present in ascending colon • Size ○ 2-4 mm thick septa – Can reduce lumen to pinhole size • Morphology ○ Circumferential, ring-like ○ Patient may have 20-50+ strictures ○ Long tapered strictures have been reported as well

Fluoroscopic Findings • Enteroclysis ○ Strictures may resemble normal plicae circulares – May be easily missed unless they cause SB obstruction ○ Mucosal erosions or ulcerations – Fluoroscopy may identify ulcers and bowel spasm

CT Findings • Stricture(s): Short segmental narrowing of lumen ○ Dilation of SB upstream from stricture • Mucosal inflammation: Mucosal hyperenhancement and submucosal edema • Bowel perforation: Free intraperitoneal air and fluid (rare)

Small Intestine Vasculitis • Long segments of submucosal edema

PATHOLOGY General Features • Etiology ○ Chronic NSAIDs use – All NSAID (including aspirin) formulations can cause enterocolitis □ Slow-release formulations affect distal small bowel or colon – Also associated with celecoxib (selective COX-2 inhibitor)

Gross Pathologic & Surgical Features • Multiple strictures with small central openings • Superficial or deep ulcerations may be seen

Microscopic Features • Transmural inflammation • Submucosal deposition of collagen fiber

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic or pain due to bowel obstruction • Other signs/symptoms ○ Occult blood loss, anemia

Imaging Recommendations

Treatment

• Best imaging tool ○ Enteroclysis or CT enterography ○ Capsule endoscopy – Capsule may fail to pass through tight stricture ○ Enteroscopy and colonoscopy can directly visualize strictures within reach of scope – Double-balloon enteroscopy may reach more distal SB

• Cessation of NSAIDs use • May require surgery or endoscopic balloon dilation for bowel obstruction

DIFFERENTIAL DIAGNOSIS Crohn Disease • Segmental areas of ileocolonic ulceration on barium study ○ Cobblestoning: Longitudinal and transverse ulcers • CT: Mucosal hyperenhancement, submucosal edema, mesenteric adenopathy

Celiac-Sprue Disease • Enteroclysis: number of jejunal folds (< 3 inches) and number of ileal folds (4-6 inches)

Small Intestine

○ Jejunoileal fold pattern reversal: Sensitivity in diagnosing disease increases to 83%

TERMINOLOGY

DIAGNOSTIC CHECKLIST Consider • Consider NSAID enteritis for patients with focal strictures of bowel

SELECTED REFERENCES 1.

2. 3. 4.

Gill RS et al: Small bowel stricture characterization and outcomes of dilatation by double-balloon enteroscopy: a single-centre experience. Therap Adv Gastroenterol. 7(3):108-14, 2014 Kishi T et al: CT enteroclysis/enterography findings in drug-induced smallbowel damage. Br J Radiol. 87(1044):20140367, 2014 Lim YJ et al: Recent advances in NSAIDs-induced enteropathy therapeutics: new options, new challenges. Gastroenterol Res Pract. 2013:761060, 2013 Scholz FJ et al: Diaphragmlike strictures of the small bowel associated with use of nonsteroidal antiinflammatory drugs. AJR Am J Roentgenol. 162(1):49-50, 1994

383

Small Intestine

Intestinal Lymphangiectasia KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Primary intestinal lymphangiectasia (Waldmann disease) ○ Rare disease or syndrome characterized by hypoproteinemia, peripheral edema, and lymphocytopenia resulting from loss of lymphatic fluid into intestine • Important cause of protein-losing enteropathy

• Whipple disease, lymphoma, intestinal opportunistic infections

IMAGING • Diffuse small bowel (SB) wall thickening with submucosal edema • Infiltration of small bowel mesentery • ± mesenteric and retroperitoneal lymphadenopathy • ± short segment, nonobstructing SB intussusceptions • For secondary form of lymphangiectasia ○ May see signs of cardiac failure, retroperitoneal fibrosis or tumor, tuberculosis, etc.

(Left) This young man had lower extremity edema, hypoproteinemia, and diarrhea. A film from a small bowel follow-through shows diffuse, nodular, thickened folds throughout the entire SB, proved to be due to lymphangiectasia. (Right) This 36-year-old woman has chronic diarrhea and lower extremity edema. CT shows fluid-distended SB with submucosal edema . More striking is the marked edema within the mesentery .

(Left) CT in the same patient shows more of the SB wall thickening , mesenteric edema , as well as ascites and enlarged, low density lymph nodes . (Right) CT in the same patient shows more of the fluid-distended SB and colon and additional hypodense nodes or infiltration at the root of the SB mesentery . Intestinal lymphangiectasia was the final diagnosis.

384

PATHOLOGY • Primary form ○ Congenital abnormality of lymphatic development • Secondary form ○ Lymphatic obstruction of lacteals draining SB • Both forms result in decreased absorption of chylomicrons and fat-soluble vitamins, excessive leakage of lymph into bowel lumen, and excessive loss of protein • Diagnosis is made by intestinal biopsy

CLINICAL ISSUES • Diarrhea, steatorrhea, peripheral edema, growth retardation • Primary lymphangiectasia is usually diagnosed in children or in young adults

Intestinal Lymphangiectasia

Synonyms • Primary intestinal lymphangiectasia (Waldmann disease)

Definitions • Rare disease or syndrome characterized by hypoproteinemia, peripheral edema, and lymphocytopenia resulting from loss of lymphatic fluid into intestine • Important cause of protein-losing enteropathy

IMAGING

○ Chylous ascites results from serosal and mesenteric lymphatic obstruction ○ Continual loss of protein (especially albumin) allows fluid to leak out of vessels and results in edema • Associated abnormalities ○ Loss of proteins (antibodies, gamma globulins) and lymphocytes leads to impaired immune system ○ Loss of fat-soluble vitamins, iron, and lipids can lead to nutritional deficiencies and anemia ○ Can be caused by any retroperitoneal or abdominal tumor, retroperitoneal fibrosis, sclerosing mesenteritis, celiac disease, scleroderma, heart failure, sarcoidosis

Radiographic Findings

Staging, Grading, & Classification

• Barium small bowel (SB) follow-through ○ Diffuse fold thickening of jejunum and ileum

• Diagnosis is made by intestinal biopsy ○ May require "double-balloon" enteroscopy to advance endoscope into SB

CT Findings • Diffuse SB wall thickening with submucosal edema • Infiltration of small bowel mesentery • ± mesenteric and retroperitoneal lymphadenopathy ○ May be soft tissue or lower density • ± short-segment, nonobstructing SB intussusceptions • ± ascites, usually small amount • For secondary form of lymphangiectasia ○ May see signs of cardiac failure, retroperitoneal fibrosis or tumor, tuberculosis, etc.

DIFFERENTIAL DIAGNOSIS Whipple Disease • Probably indistinguishable from lymphangiectasia by imaging • Clinical findings (arthralgias, pigmentation, anemia, CNS symptoms) are different • Diagnosis by SB biopsy with PAS(+) material and bacilli

Lymphoma • • • •

May cause or simulate lymphangiectasia Lymphadenopathy usually more prominent Less diarrhea and protein-losing enteropathy Diagnosis by biopsy

Intestinal Opportunistic Infections • May cause or simulate lymphangiectasia • Giardiasis, cryptosporidiosis, etc. • Mycobacterial disease especially ○ Can cause small bowel fold thickening, mesenteric, and retroperitoneal lymphadenopathy

PATHOLOGY General Features • Etiology ○ Primary form – Congenital abnormality of lymphatic development ○ Secondary form – Lymphatic obstruction of lacteals draining SB (by tumor, infection, etc.) ○ Both forms result in abnormal (deficient) absorption of chylomicrons and fat-soluble vitamins, excessive leakage of lymph into bowel lumen, and excessive loss of protein

Small Intestine

TERMINOLOGY

Microscopic Features • Secondary form: Biopsy may also reveal deposition of other abnormal cells (e.g., lymphoma, monoclonal IgG in Waldenström macroglobulinemia) • Dilated intestinal lacteals

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Diarrhea (present in 80% of patients), steatorrhea (20%), malabsorption ○ Ascites, pleural effusion, lower extremity edema ○ Hypoproteinemia, lymphocytopenia, hypogammaglobulinemia • Other signs/symptoms ○ Weight loss, muscle wasting ○ Macular edema; may lead to blindness ○ Pachydermoperiostitis (thick skin and periosteal new bone) with clubbing of fingers

Demographics • Age ○ Primary lymphangiectasia is usually diagnosed in children or in young adults ○ Secondary form can develop at any age, usually older adults

Natural History & Prognosis • Depends on etiology (worse if due to advanced malignancy) • Primary form may result in growth retardation

SELECTED REFERENCES 1.

2. 3.

4. 5.

Wen Z et al: The lymphoscintigraphic manifestation of (99m)Tc-dextran lymphatic imaging in primary intestinal lymphangiectasia. Nucl Med Commun. 35(5):493-500, 2014 Ersoy O et al: Evaluation of primary intestinal lymphangiectasia by capsule endoscopy. Endoscopy. 45 Suppl 2 UCTN:E61-2, 2013 Urganci N et al: Evaluation of paediatric patients with protein losing enteropathy a single centre experience. West Indian Med J. 62(3):186-9, 2013 Hauser B et al: Intestinal lymphangiectasia. J Pediatr Gastroenterol Nutr. 48(2):125, 2009 Lobato Salinas Z et al: [Primary intestinal lymphangiectasia. A rare diagnosis of protein-losing enteropathy.] An Pediatr (Barc). 70(6):606-8, 2009

385

Small Intestine

Ileus KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Proportional gaseous dilatation of large and small bowel due to lack of intestinal peristalsis, not mechanical obstruction

• Postoperative ileus is most common cause of delayed discharge from hospital ○ Usually resolves spontaneously in 3-7 days • Most common signs/symptoms ○ Tympanic abdomen on percussion, lack of flatus ○ Gaseous distension, abdominal pain, nausea, and vomiting ○ Absence of bowel sounds on auscultation • Treatment ○ Treat underlying etiology (e.g., hypokalemia, sepsis) ○ IV fluids, nasogastric suction

IMAGING • CT or abdominal plain films (supine, upright, decubitus) • Proportional dilatation of SB and colon with no transition point ○ SB > 3 cm on plain films, 2.5 cm on CT ○ Air-fluid levels on upright and decubitus films

TOP DIFFERENTIAL DIAGNOSES • • • •

SB or colonic obstruction Intestinal pseudoobstruction Ogilvie syndrome Aerophagia

(Left) Supine abdominal radiograph in an 88-year-old man with abdominal distension and hypokalemia from diuretic use shows proportional dilation of the large and small bowel with no clear transition point. The ileus resolved with electrolyte replacement. (Right) Supine radiograph in a 90-year-old woman with abdominal distension and pain following a hip "pinning" shows gaseous dilation of the colon and the small bowel in a uniform pattern with no point of transition.

(Left) This 52-year-old woman has cirrhosis with increasing abdominal distention and nausea. A supine abdominal film, requested to evaluate possible SBO, shows dilated transverse colon and small bowel , but no gas in other colon segments. Ascites fills the pelvis and paracolic gutters. (Right) CT in the same patient shows ascites and fluid-distended bowel . Gas fills only a portion of the nondependent bowel, while the dependent SB & colon are fluid-filled & less dilated. This may be misinterpreted as SB obstruction.

386

DIAGNOSTIC CHECKLIST • Pitfalls: Ileus plus ascites, and recent bowel surgery mimic SBO on plain films ○ CT can be used to resolve issue if necessary

Ileus

Definitions • Proportional gaseous dilatation of large and small bowel (SB) due to lack of intestinal peristalsis, not mechanical obstruction

IMAGING General Features • Best diagnostic clue ○ Proportional dilatation of large and small intestine on plain films with no transition point

Imaging Recommendations • Best imaging tool ○ Plain abdominal radiography, including supine and upright or decubitus views ○ Multiplanar CT is more accurate with fewer imaging pitfalls • Protocol advice ○ Oral contrast may not be tolerated and is rarely necessary for CT

Radiographic Findings • Radiography ○ Symmetric dilatation of large and small bowel – SB diameter > 3 cm (larger than on CT measurements due to magnification on plain radiography) ○ Air-fluid levels on upright and decubitus films ○ Pitfall: Ileus plus ascites mimics small bowel obstruction (SBO) – Gas collects mostly in mesenteric bowel (SB, transverse, and sigmoid colon) – Retroperitoneal colon segments remain mostly gasfree, invisible on supine films – CT can easily resolve this, showing generalized dilation of SB and colon without transition point ○ Recent bowel surgery; plain film findings mimic SBO – SB will be dilated to point of bowel incision – This can be a form of ileus and usually resolves spontaneously

Fluoroscopic Findings • Upper GI ○ Delayed transit of contrast through small bowel ○ No mechanical obstruction or transition to collapsed SB • Contrast enema ○ No colonic obstruction ○ Contrast flows to ileocecal valve without difficulty

CT Findings • Dilated large and small bowel ○ SB diameter > 2.5 cm

DIFFERENTIAL DIAGNOSIS Small Bowel or Colonic Obstruction • Bowel dilated upstream from transition point, obstructing lesion • Small bowel feces sign found just proximal to point of obstruction

Intestinal Pseudoobstruction • Etiologies include ○ Visceral myopathy or neuropathy ○ Degenerative neurologic disorders (Parkinson disease) ○ Scleroderma

Small Intestine

TERMINOLOGY

Ogilvie Syndrome • Acute colonic pseudoobstruction (common in postoperative and septic patients) • Often involves right colon and cecum > transverse colon

Aerophagia • Air-swallowing, common in hospitalized patients • Especially those with enteric feeding tubes • Excess gas within nondilated stomach, SB, colon

PATHOLOGY General Features • Etiology ○ Abdominal surgery, general anesthesia ○ Opioid (narcotic) drug use ○ Electrolyte disturbance (especially hypokalemia), hypothyroidism ○ Stress-induced sympathetic reflexes, cytokine-mediated inflammatory factors ○ Sepsis (especially peritonitis), mesenteric ischemia, ureteral colic ○ Retroperitoneal hemorrhage, acute myocardial infarction, spinal cord injury

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Gaseous distension, abdominal pain, nausea, and vomiting • Other signs/symptoms ○ Constipation, bloating, lack of bowel sounds on auscultation ○ Tympanic abdomen on percussion, lack of flatus

Demographics • Epidemiology ○ Postoperative ileus is most common cause of delayed discharge from hospital

Natural History & Prognosis • Postoperative ileus most often resolves spontaneously in 37 days

Treatment • Treat underlying etiology (e.g., hypokalemia, sepsis) • IV fluids, nasogastric suction

SELECTED REFERENCES 1. 2. 3.

Blumenfeld YJ et al: Risk factors for prolonged postpartum length of stay following cesarean delivery. Am J Perinatol. ePub, 2015 Gan TJ et al: Impact of postsurgical opioid use and ileus on economic outcomes in gastrointestinal surgeries. Curr Med Res Opin. 1-28, 2015 Moss G: The etiology and prevention of feeding intolerance paralytic ileus revisiting an old concept. Ann Surg Innov Res. 3:3, 2009

387

Small Intestine

Small Bowel Obstruction KEY FACTS

• Obstruction or blockage of 1 small bowel (SB) segments by intrinsic or extrinsic narrowing of SB lumen

IMAGING • SB > 3 cm diameter on radiographs, 2.5 cm on CT ○ Air-fluid levels on upright or decubitus radiograph • Small bowel feces sign: Gas bubbles mixed with particulate matter in dilated loops just proximal to site of obstruction • Closed loop obstruction ○ SB segments are markedly distended (> 4 cm) by fluid, little gas ○ Whirl sign due to tightly twisted mesenteric vessels ○ "Balloons-on-strings": Dilated SB tethered by stretched mesenteric vessels • Strangulating SBO: Impaired blood supply to SB ○ Absent, decreased, or delayed bowel wall enhancement ○ Bowel wall thickening (edema or hemorrhage) ○ Mesenteric and interloop edema ± ascites

(Left) Anteroposterior graphic depiction of a small bowel obstruction (SBO) due to an adhesive band. Note the dilation of the proximal small bowel , as well as the adhesive band . (Right) In this patient with abdominal pain, distention, and nausea, a supine film of the abdomen shows no obvious dilation of small bowel (SB).

(Left) An upright film in the same patient shows a stringof-pearls sign , indicating gas within fluid-distended, obstructed segments of SB. (Right) Axial CT section in the same patient shows collapsed distal SB , but massive dilation of proximal SB segments with only small bubbles of intraluminal air , accounting for the string-ofpearls sign. An adhesive SBO was confirmed at surgery.

388

○ Vessels: Congested, thrombosed, or obscured

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • •

Adynamic or paralytic ileus Aerophagia Colonic obstruction Cystic fibrosis

CLINICAL ISSUES • Most common causes: Adhesions (~ 60%), hernias (15%), tumors (~ 15%; metastases > primary tumor) • Up to 80% of adhesive SBOs resolve spontaneously • Mortality > 25% if symptoms persist and surgery postponed > 36 hours • Mortality is 100% for untreated strangulated SBOs

DIAGNOSTIC CHECKLIST • CT diagnosis of closed loop or strangulated (ischemic) SBO is crucial for directing prompt surgical intervention

Small Bowel Obstruction

Abbreviations • Small bowel obstruction (SBO)

Definitions • Obstruction or blockage of 1 SB segments by intrinsic or extrinsic narrowing of SB lumen

•

IMAGING General Features • Best diagnostic clue ○ Identification of transition zone between dilated and collapsed bowel is critical to define presence, site, and cause of obstruction (all better determined on CT than on plain films) • Size ○ Small bowel loops > 3 cm diameter on radiographs, 2.5 cm on CT (magnification effect on plain films)

Radiographic Findings • Radiography ○ Supine abdomen with upright or decubitus views – Dilated SB loops with air-fluid levels on upright or decubitus radiograph ○ Can miss SBO (fluid-distended bowel not evident on plain films) ○ String-of-pearls sign: Small air bubbles within fluiddistended bowel seen on supine view

•

•

Fluoroscopic Findings • Enteroclysis or SB series ○ Passage of enteric contrast into colon excludes complete SBO ○ Transition may define location, degree, cause of obstruction – e.g., angulated segment with distortion of folds suggests adhesive SBO

CT Findings • Dilated SB loops > 2.5 cm diameter ± air-fluid levels • Small bowel feces sign: Gas bubbles mixed with particulate matter in dilated loops just proximal to site of obstruction • Extrinsic lesions ○ Adhesions – At transition, angulation of course of SB, minimal mural thickening – Adhesions themselves are not identified on CT – Adhesive SBO is diagnosis of exclusion; no hernia or mass ○ Hernia – External hernias (inguinal, femoral, Spigelian, obturator, etc.) □ Most common type of hernia to cause SBO – Internal hernia: Cluster of dilated SB segments; crowding, twisting, displacement of mesenteric vessels – Dilated segment of SB leading into hernia; collapsed segment leaving hernia – Strangulated hernia: Thickened bowel wall ± intramural hemorrhage

•

○ Peritoneal carcinomatosis: Omental and peritoneal masses, dilated bowel loops, multiple transition zones – Metastases may cause luminal obstruction or functional obstruction due to serosal coating (impairs peristalsis) ○ Other inflammatory causes (appendicitis, diverticulitis, etc.) Intrinsic lesions ○ Malignant tumor (adenocarcinoma, GIST, carcinoid, etc.) – Thickened enhancing wall and luminal narrowing at transition zone ○ Crohn disease – Mucosal hyperenhancement, submucosal edema over long segment of distal SB ○ Intussusception – Bowel-within-bowel – Layers of bowel wall interspersed with mesenteric fat and vessels ○ Other infectious, ischemic, or inflammatory – e.g., radiation or ischemic stricture, tuberculous enterocolitis Intraluminal lesions: Gallstones, foreign bodies, bezoars, Ascaris ○ Classic triad: Ectopic calcified stone and gas in gall bladder/biliary tree and SBO = gallstone ileus ○ Bezoar: Intraluminal mass with air in interstices at point of transition Closed loop obstruction: Obstruction at 2 points, involves mesentery ○ Affected SB segments are markedly distended (> 4 cm) by fluid, little gas ○ Relatively little dilatation of bowel proximal to closed loop obstruction ○ Stretched mesenteric vessels converging toward site of torsion ○ Beak sign: Fusiform tapering at point of torsion/obstruction ○ Volvulus: C-shaped, U-shaped, or "coffee bean" SB configuration – Whirl sign due to tightly twisted mesenteric vessels – "Balloons-on-strings": Appearance of dilated SB tethered by stretched mesenteric vessels Strangulating SBO: Blood flow to affected SB is blocked ○ Absent, decreased, or delayed bowel wall enhancement in affected SB ○ Bowel wall thickening (edema or hemorrhage) – High density of SB wall on NECT = hemorrhage = ischemia ○ Mesenteric and interloop edema ± ascites ○ Combination of factors obscures margins among affected SB segments ○ Mesenteric vessels: Congested, thrombosed or obscured by adjacent edema

Small Intestine

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Multiplanar CECT: Sensitivity 95%, specificity 96% in highgrade SBO – CT evaluation is mandatory in patients with □ Suspected bowel ischemia □ Suspected abdominal sepsis 389

Small Intestine

Small Bowel Obstruction □ History of inflammatory bowel disease □ Known or suspected cancer ○ Enteroclysis: Most sensitive test for patients with intermittent, low-grade SBO • Protocol advice ○ Administration of positive oral contrast medium is rarely useful and may impede CT detection of complications of SBO, such as ischemia

DIFFERENTIAL DIAGNOSIS Adynamic or Paralytic Ileus • Dilated SB and colon with no transition point • Ileus plus ascites mimics SBO ○ Gas collects in nondependent SB and transverse colon ○ Minimal gas in dependent colon and rectum

Aerophagia • Excessive air swallowing: Belching, flatulence, distention • Excess gas in stomach, SB, and colon without much dilation or air-fluid levels

Colonic Obstruction • Dilation of colon due to mechanical causes (cancer, volvulus)

Cystic Fibrosis (CF) • "DIOS": Distal intestinal obstruction syndrome • Functional obstruction of SB due to thick, viscous bowel contents • Small bowel feces sign in distal ileum • Look for lipomatous pseudohypertrophy of pancreas, lung damage from CF

PATHOLOGY General Features • Etiology ○ Most common: Adhesions (~ 60%), hernias (15%), tumors (~ 15%; metastases > primary tumor) ○ Etiology of ischemia in SBO – Twisting and occlusion of mesenteric vessels (common in closed loop SBO) – Luminal distention causes occlusion of small vessels in SB wall

Staging, Grading, & Classification • Classification based on degree of obstruction ○ Simple – Intermittent, incomplete, or partial low-grade obstruction – Prolonged, complete, or high-grade obstruction ○ Complicated – Closed loop or incarcerated obstruction: Adhesive bands > internal or external hernia – Strangulation: Most common complication of closed loop obstruction, indicates vascular compromise

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Variable: Mild to severe abdominal pain with vomiting 390

– Abdominal distention, tenderness, guarding – Bowel sounds high pitched (early) or absent (late sign)

Demographics • Epidemiology ○ Accounts for 20% of acute abdomen presentations

Natural History & Prognosis • Complications ○ Bowel strangulation, infarction, gangrene, perforation, peritonitis, and sepsis • Prognosis ○ Up to 80% of adhesive SBOs resolve spontaneously ○ Mortality > 25% if symptoms persist and surgery postponed > 36 hours ○ Mortality decreased to 8% if surgery performed 36 hours ○ Mortality is 100% for untreated strangulated (ischemic) SBOs

Treatment • Nasogastric suction, decompression, IV fluids • Nonoperative treatment for incomplete SBO with early resolution of symptoms • Immediate surgery for complete SBO or closed loop obstruction

DIAGNOSTIC CHECKLIST Consider • CT diagnosis of closed loop or strangulated (ischemic) SBO is crucial for directing prompt surgical intervention

Image Interpretation Pearls • Know the CT signs for closed loop or ischemic SBO

SELECTED REFERENCES 1.

2.

3.

4.

5.

6. 7. 8.

Geffroy Y et al: Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction. Radiology. 270(1):159-67, 2014 Keenan JE et al: Trials of nonoperative management exceeding 3 days are associated with increased morbidity in patients undergoing surgery for uncomplicated adhesive small bowel obstruction. J Trauma Acute Care Surg. 76(6):1367-72, 2014 Millet I et al: Adhesive small-bowel obstruction: value of CT in identifying findings associated with the effectiveness of nonsurgical treatment. Radiology. 273(2):425-32, 2014 O'Leary EA et al: Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate? Am Surg. 80(6):572-9, 2014 Suri RR et al: Computed tomography features associated with operative management for nonstrangulating small bowel obstruction. Can J Surg. 57(4):254-9, 2014 Barnett RE et al: Accuracy of computed tomography in small bowel obstruction. Am Surg. 79(6):641-3, 2013 van Oudheusden TR et al: Challenges in diagnosing adhesive small bowel obstruction. World J Gastroenterol. 19(43):7489-93, 2013 Delabrousse E et al: Small-bowel obstruction from adhesive bands and matted adhesions: CT differentiation. AJR Am J Roentgenol. 192(3):693-7, 2009

Small Bowel Obstruction Small Intestine

(Left) This patient had a prior surgical history and now presents with nausea and vomiting. Axial CT shows the dilated proximal SB and decompressed bowel distal to the transition site. (Right) A coronal-reformatted CT image in the same patient shows the transition from dilated to collapsed SB. No mass, hernia, or other specific cause was identified, leading to the inference that this was an adhesive SBO, subsequently confirmed at surgery.

(Left) This elderly woman has abdominal pain, distention, and vomiting. Axial CT shows markedly dilated proximal SB segments , while distal SB and colon are decompressed . (Right) A more caudal CT section in the same patient shows dilated SB entering a right femoral hernia.

(Left) A more caudal CT section in the same patient shows a "knuckle" of SB trapped within the femoral hernia, establishing this as the transition point and etiology of the SBO. (Right) A coronalreformatted CT section in the same patient shows the transition point, as the dilated SB enters the right femoral hernia . Hernias are the 2nd most common etiology for SBO, though much less common than adhesive SBO.

391

Small Intestine

Small Bowel Obstruction

(Left) This woman has metastatic ovarian carcinoma and has had prior bowel resection and ileostomy for SBO. CT shows the ileostomy and SB segments that are matted together without definable mesenteric fat between SB segments. (Right) Another CT section in the same patient shows SB loops that are encased and angulated due to serosal implants of recurrent ovarian carcinoma. Almost 1/2 of all women with ovarian carcinoma will develop symptoms of SBO.

(Left) This young man has cystic fibrosis with recurrent abdominal pain and distention. CT shows contrast material in decompressed colon , the result of prior attempts at colon cleansing by water-soluble contrast enema. The SB is markedly distended with a small bowel feces sign in the distal ileum . This is a classic example of DIOS (distal intestinal obstruction syndrome) in a patient with cystic fibrosis. (Right) A coronal image in the same patient shows the collapsed colon and the dilated SB with DIOS .

(Left) This young man has longstanding Crohn disease with progressive abdominal distention and pain. Axial CT shows massive dilation of some SB segments, some of which have air-fluid levels . The colon is decompressed. (Right) Coronal CT section in the same patient shows the dilated, more proximal SB with the transition point being more distal SB, featuring mucosal hyperenhancement, submucosal edema, and luminal narrowing . Mesenteric lymphadenopathy is another typical feature of Crohn disease.

392

Small Bowel Obstruction Small Intestine

(Left) This elderly man has abdominal distention and pain. A supine film of the abdomen shows moderate gas dilation of proximal SB segments , but minimal gas in the distal SB and colon. Instead, there is a suggestion of a lower abdominal mass . (Right) Axial NECT in the same patient shows dilated mid SB segments that are almost entirely fluid-filled with little gas, accounting for the mass seen on the supine film. Mesenteric vessels to these segments are engorged and crowded with blurred margins. Ascites is present .

(Left) Another CT section in this patient shows a whirl sign , twisting of the SB mesenteric vessels. (Right) Another CT section in this patient shows poor definition of the margins among the dilated SB segments , owing to infiltration of the SB mesentery and localized ascites between the affected SB loops. The mesenteric vessels are acutely angulated.

(Left) A coronal CT section in the same patient shows a classic "balloons-on-strings" appearance of the fluiddistended SB segments tethered by their stretched mesenteric vessels. (Right) A sagittal CT section in the same patient also demonstrates the "balloons-on-strings" appearance , with the "strings" being the mesenteric vessels and the "balloons" the SB segments within a closed loop SBO. This patient has many classic CT features of a closed loop SBO with ischemia, confirmed at surgery.

393

Small Intestine

Pneumatosis of the Intestine KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Pneumatosis is a descriptive sign, not a disease or diagnosis ○ Cystic or linear collections of gas in subserosal or submucosal layers of GI tract wall • Pneumatosis intestinalis: Most common form of intramural gas, found in SB more often than colon • Pneumatosis coli: Rounded collections of gas in distal colonic wall, usually asymptomatic finding

• • • • • • •

IMAGING

CLINICAL ISSUES

• Best imaging tool: MDCT with lung windows to detect intramural, intraperitoneal, and venous gas • Pneumatosis of ischemic etiology ○ Dilated bowel lumen (ileus), thickened wall, abnormal wall enhancement – Ascites, may be of blood density (> 35 HU) – ± pneumoperitoneum or pneumoretroperitoneum – ± mesenteric or portal venous gas • Portal venous gas is not always due to bowel infarction

• Most common signs/symptoms ○ Nonischemic causes: Patients are often asymptomatic ○ Bowel ischemia: Nausea, abdominal pain, distension, melena, fever, vomiting, cough (depending on etiology) • Treatment and prognosis depend on etiology • Direct communication with clinical team is essential

(Left) CT in a 50-year-old man on chronic steroid medication for psoriasis shows gas within the colon wall , but the colon and SB show normal caliber. Note the free intraperitoneal gas . This was a persistent asymptomatic finding attributed to medication. (Right) CT shows extensive pneumatosis throughout the SB. Bowel distention and ascites help to confirm that the pneumatosis is likely on the basis of bowel ischemia, rather than one of the "benign" (nonischemic) causes of pneumatosis.

(Left) Axial CECT in a 75-yearold man who presented with abdominal pain and prior bowel ischemia demonstrates relatively subtle gas within the peripheral intrahepatic branches of the portal vein . (Right) Axial CECT in the same patient reveals extensive pneumatosis within dilated segments of the bowel . Ascites is also noted near the damaged bowel. The patient went to surgery for resection of the infarcted bowel.

394

Bowel necrosis Post endoscopy Postoperative Medication induced Autoimmune disease Pulmonary disease Pseudopneumatosis

Pneumatosis of the Intestine

Definitions • Cystic or linear collections of gas in subserosal or submucosal layers of gastrointestinal (GI) tract wall • Pneumatosis intestinalis: Most common form of intramural gas, found in small bowel more often than colon • Pneumatosis coli: Rounded collections of gas in distal colonic wall, usually asymptomatic finding • Pneumatosis is a descriptive sign, not a disease or diagnosis

IMAGING General Features • Best diagnostic clue ○ Cystic or linear distribution of gas along bowel wall on CT

Fluoroscopic Findings • Barium studies ○ Pneumatosis intestinalis – Mottled, bubbly, or linear collections of gas in bowel wall; feces-like appearance – Dilated bowel loops ± thumbprinting ○ Pneumatosis coli – Radiolucent cysts resembling polyps, clustered along colonic contours – Multiple large gas-filled cysts with scalloped defects in bowel wall, mimicking inflammatory pseudopolyps – Concentric compression of colonic lumen by cysts – Striking lucency of gas-filled cysts

– Multiplanar reformation is essential

DIFFERENTIAL DIAGNOSIS Bowel Necrosis • Ischemic enteritis, volvulus, necrotizing enterocolitis • Mucosal damage entry of bacteria (mainly enteric organisms) into bowel wall gas in wall • Necrotizing enterocolitis ○ Premature or debilitated infants ○ Affects ileum and right colon ○ Feces-like appearance in right bowel ○ Gas in intrahepatic branches of portal vein: Catastrophic sign • Ischemic colitis or enteritis ○ Colonic ischemia is often due to hypoperfusion in elderly or debilitated ○ Small bowel infarction often due to embolus, thrombus of large vessels (superior mesenteric artery or vein) – Associated mesenteric infiltration greater with SMV thrombosis ○ Late phase of ischemia diffuse or localized pneumatosis intestinalis ± mesenteric or portal venous gas – Pneumatosis intestinalis can occur with either transmural or partial mural ischemia

Post Endoscopy • Mucosal disruption and increased luminal pressure distension air dissection into wall

CT Findings

Postoperative

• CECT ○ Pneumatosis intestinalis – Band-like: Bands or linear distribution of gas in affected bowel wall – Linear or curvilinear shape – Ischemic etiology: Dilated bowel lumen (ileus), thickened wall, abnormal enhancement □ Ascites, may be of blood density (> 35 HU) □ ± mesenteric arterial or venous thrombosis – ± pneumoperitoneum or pneumoretroperitoneum – ± mesenteric or portal venous gas □ Portal venous gas collects in liver periphery □ Biliary gas collects in central ducts near porta hepatis – Nonischemic causes: Ileus and ascites are usually absent ○ Pneumatosis coli – Bubble-like: Isolated collections of air or clusters of cysts in left colonic wall – Usually not accompanied by ileus, ascites, or clinical signs of acute abdominal process

• Intestinal bypass or anastomosis • Enteral tube feeding (e.g., jejunostomy tube) • Mucosal disruption and increased luminal pressure distension air dissection into wall

Imaging Recommendations • Best imaging tool ○ Multiplanar CT with lung windows to detect gas • Protocol advice ○ CT with IV contrast at 3-4 mL/sec, 1.5-3 mm collimation – 35-second image delay, repeat venous phase after 80 seconds ○ Water for oral contrast facilitates CT angiography

Small Intestine

TERMINOLOGY

bowel

bowel

Medication Induced • Steroids or immunosuppressives > chemotherapy • Increased mucosal permeability, decreased immune system bacterial gas enters bowel wall

Autoimmune Disease • e.g., systemic lupus erythematosus (SLE) • Increased mucosal permeability, decreased immune system bacterial gas enters bowel wall

Pulmonary Disease • Chronic obstructive pulmonary disease (COPD) and ventilator (barotrauma) ○ Partial bronchial obstruction and coughing leads to alveolar rupture ○ Air dissects into peribronchial and perivascular tissue planes of mediastinum ○ Hiatus of esophagus and aorta allows access to retroperitoneum and mesentery ○ Further progression to subserosa and submucosa of bowel wall

Pseudopneumatosis • Gas trapped against mucosal surface of bowel by semisolid feces • Most common in ascending colon 395

Small Intestine

Pneumatosis of the Intestine

PATHOLOGY General Features • Etiology ○ Portal venous gas – Often accompanies pneumatosis intestinalis □ Amount of gas does not correlate with etiology, prognosis, or need for treatment □ Not always due to bowel infarction □ Increased likelihood of transmural infarction from ischemic enteritis vs. ischemic colitis – Intestinal wall lesions: Ischemia, IBD – Bowel distention: Endoscopy, obstruction, trauma – Sepsis: Diverticulitis, cholecystitis, appendicitis, colitis including Clostridium difficile infection

Staging, Grading, & Classification • Pneumatosis is classified by some as primary or secondary ○ Primary usually refers to pneumatosis colis; insignificant, asymptomatic, idiopathic ○ Secondary usually refers to pneumatosis intestinalis and has a range of etiologies and clinical implications

Microscopic Features • Pneumatosis intestinalis ○ Linear streaks of gas parallel to bowel wall ○ Necrotic, inflammatory, ulcerative, or ischemic features are often found, depending on etiology • Pneumatosis coli ○ Multiple thin-walled, noncommunicating, gas-filled cysts in subserosal or submucosal layer of bowel ○ Normal muscularis and mucosa

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pneumatosis intestinalis: Symptoms range from none to abdominal pain, distension, melena, fever, vomiting, cough (depending on etiology) ○ Pneumatosis coli: Asymptomatic; insignificant

Demographics • Age ○ Primary: Adults ○ Secondary: Any age • Gender ○ M=F

Natural History & Prognosis • Prognosis ○ Depends on etiology (not extent) of gas ○ Detection of pneumatosis and portomesenteric venous gas – Detected on radiography: 75% mortality – Detected on CT (more sensitive): 25% mortality ○ Pneumatosis is associated with pneumoperitoneum or portal venous gas can be benign, transient ○ Benign or catastrophic prognosis cannot be distinguished by imaging • Complications: Spontaneous rupture of pneumatosis pneumoperitoneum 396

Treatment • Pneumatosis intestinalis: Dependent on etiology ○ Oxygen may be beneficial: Decreases gas tension in tissues ○ No treatment is generally necessary for nonischemic causes of pneumatosis ○ Some patients with pneumatosis due to bowel ischemia are clinically stable following fluid resuscitation and resolution of ischemic injury; may not require surgery ○ Patients with transmural bowel necrosis usually require urgent resection of necrotic bowel • Pneumatosis coli: No treatment, resolves spontaneously or persists without symptoms

Laboratory Findings • Patients with ischemic bowel injury usually have elevated serum lactate (acidosis), leukocytosis and may have elevated serum amylase

DIAGNOSTIC CHECKLIST Consider • Bowel necrosis is a surgical emergency • Prognosis depends on underlying cause of pneumatosis, not imaging findings • Nonischemic causes of pneumatosis are usually asymptomatic; little clinical significance

Image Interpretation Pearls • Important to recognize pneumatosis, but significance depends on etiology and clinical setting • Recognition of pneumatosis demands direct communication with clinical team to determine its likely etiology and optimal management

SELECTED REFERENCES 1.

Milone M et al: Computed tomography findings of pneumatosis and portomesenteric venous gas in acute bowel ischemia. World J Gastroenterol. 19(39):6579-84, 2013 2. Zorgdrager M et al: Pneumatosis intestinalis associated with enteral tube feeding. BMJ Case Rep. 2013, 2013 3. Pickhardt PJ et al: Asymptomatic pneumatosis at CT colonography: a benign self-limited imaging finding distinct from perforation. AJR Am J Roentgenol. 190(2):W112-7, 2008 4. Saba L et al: Computed tomographic imaging findings of bowel ischemia. J Comput Assist Tomogr. 32(3):329-40, 2008 5. Kim BN et al: Pneumatosis cystoides coli of the ascending colon: colonoscopic and CT colonographic features. Endoscopy. 39 Suppl 1:E73-4, 2007 6. Kim KM et al: CT Colonography of pneumatosis cystoides intestinalis. Abdom Imaging. 32(5):602-5, 2007 7. Mikami S et al: Education and imaging. Gastrointestinal: pneumatosis of the ascending colon. J Gastroenterol Hepatol. 22(5):760, 2007 8. Romano S et al: Multidetector row computed tomography findings from ischemia to infarction of the large bowel. Eur J Radiol. 61(3):433-41, 2007 9. Liu KL et al: Gastrointestinal: pneumatosis coli. J Gastroenterol Hepatol. 21(4):772, 2006 10. Hou SK et al: Hepatic portal venous gas: clinical significance of computed tomography findings. Am J Emerg Med. 22(3):214-8, 2004

Pneumatosis of the Intestine Small Intestine

(Left) This 54-year-old woman had a recent stem cell transplant and had abdominal distention. A supine film shows extensive pneumatosis within the colonic and SB walls. (Right) CT in the same patient shows gas within the bowel wall , but no ascites or ileus. The patient remained relatively asymptomatic, confirming this as "benign" (nonischemic) pneumatosis, likely due to medications.

(Left) Axial CECT in an elderly man demonstrates extensive gas within the mesenteric and intrahepatic portal veins . (Right) Axial CECT in the same patient reveals ascites , extensive SB dilation and pneumatosis , as well as the previously noted gas within mesenteric veins and intrahepatic portal veins. This combination of findings is essentially diagnostic of transmural bowel infarction.

(Left) Contrast enema in a patient with abdominal pain and distension shows polypoid lesions representing gas "cysts" within the colon wall. The barium outlines mucosal distortion. It is critical to recognize the submucosal presence of gas density , which is diagnostic for pneumatosis. Despite the interpretation of benign pneumatosis coli, this patient was taken to surgery. (Right) Photograph of the resected colon specimen in the same patient shows submucosal gas cysts , but otherwise a normal colon.

397

Small Intestine

Intussusception KEY FACTS

TERMINOLOGY

• US: "Target," "doughnut," or bull's-eye sign

• Invagination or telescoping of proximal segment of bowel (intussusceptum) into lumen of distal segment (intussuscipiens)

TOP DIFFERENTIAL DIAGNOSES

IMAGING • Location: Ileoileal > ileocolic > colocolic • Bowel-within-bowel on fluoroscopy, CT, or US ○ Outer layer = intussuscipiens; inner layer = intussusceptum ○ "Coiled spring" appearance on small bowel followthrough or enteroclysis • CT: Alternating layers of mesenteric fat and soft tissue density bowel walls ○ Enhancing mesenteric vessels accompany intussusceptum ○ CT may identify lead mass ○ Short segment, nonobstructing intussusceptions are commonly seen, rarely significant

(Left) Graphic shows an ileocolic intussusception with a tumor in the bowel wall as the lead mass. Note the vascular compromise and ischemia of the intussusceptum . (Right) Coronal CECT shows invaginated mesenteric fat and vessels from an ileocolonic intussusception. The lead mass proved to be carcinoma.

(Left) Transverse color Doppler ultrasound of SB intussusception shows vascular flow within an intraluminal mass and 2 echogenic submucosal rings representing intussusceptum and intussuscipiens . (Right) Transverse power Doppler ultrasound in the same patient reveals marked hyperemia within the mass, which proved to be a metastatic melanoma.

398

• • • •

Primary bowel tumor Metastases and lymphoma Endometrial implant Meckel diverticulum

PATHOLOGY • Tumor-related lead point ○ Benign: Polyp, leiomyoma, lipoma ○ Malignant: Primary (more common in colon), metastases and lymphoma (more common in SB) • Physical cause, but no neoplasm ○ Postoperative causes are most common (e.g., adhesions, anastomoses)

CLINICAL ISSUES • Obstruction and ischemia are more common in longsegment intussusception with lead mass

Intussusception

Definitions • Invagination or telescoping of proximal segment of bowel (intussusceptum) into lumen of distal segment (intussuscipiens)

IMAGING General Features • Best diagnostic clue ○ Bowel-within-bowel, "coiled spring" appearance • Location ○ Ileoileal > ileocolic > colocolic ○ Usually small bowel (SB) in adults, ileocolic in children ○ Colon: Malignant tumors more common than benign ○ SB: Benign tumors more common than malignant

– Multiple, thin, parallel, hypoechoic and echogenic stripes • Color Doppler ○ Mesenteric vessels dragged between entering and returning wall of intussusceptum

Imaging Recommendations • Best imaging tool ○ Depends on patient age/presentation ○ Sonography may be sufficient for diagnosis in children ○ Multiplanar CT is optimal in adults – Better depiction of presence, cause, and clinical significance of intussusception

DIFFERENTIAL DIAGNOSIS Primary Bowel Tumor

• Radiography ○ Air-fluid levels, proximal bowel dilatation, absence of gas in distal collapsed bowel

• May cause or simulate intussusception • Carcinoid tumor, adenocarcinoma, gastrointestinal stromal tumor (GIST), lipoma, adenoma • Enteroclysis or CT/MR enterography: Best for detecting mass

Fluoroscopic Findings

Metastases and Lymphoma

• Barium study ○ Classic "coiled spring" appearance – Trapping of contrast between folds of intussusceptum and intussuscipiens ○ Bowel obstruction, proximal dilatation, distal collapsed loops

• Non-Hodgkin lymphoma (more common) ○ Distribution: Stomach (51%), small bowel (33%) ○ Nodular, polypoid, infiltrating, invading mesentery ○ Sausage-shaped thickening of affected bowel wall – May cause or simulate intussusception • Metastases (SB): Malignant melanoma, lung and breast cancer ○ Melanoma in SB often presents as intussusception – Usually multifocal, intramural masses ○ Lung and breast metastases more often cause obstruction

Radiographic Findings

CT Findings • "Bowel-within-bowel" appearance ○ Outer layer represents intussuscipiens, inner layer represents intussusceptum ○ Alternating layers of mesenteric fat and soft tissue density bowel walls ○ Enhancing mesenteric vessels accompany intussusceptum • Reniform or sausage-shaped mass • Features of intestinal obstruction ○ Air-fluid levels, proximal bowel distension ○ Obstruction and ischemia are more common in longsegment intussusception with lead mass – CT may identify lead mass • Short segment, nonobstructing intussusceptions ○ Commonly seen on CT ○ Usually of no clinical significance

MR Findings • "Bowel-within-bowel" or "coiled-spring" appearance • Best seen on turbo spin-echo T2WI

Ultrasonographic Findings • Grayscale ultrasound ○ Transverse US: "Target," "doughnut," or bull's-eye sign – Peripheral hypoechoic halo: Edematous wall of intussuscipiens – Intermediate hyperechoic area: Space between intussuscipiens and intussusceptum – Internal hypoechoic ring: Wall of intussusceptum ○ Longitudinal US: Pseudokidney or hay fork sign

Small Intestine

TERMINOLOGY

Endometrial Implant • Endometrial tissue outside myometrium • Common location: Pelvic organs; bowel involved in 37% of cases • Crenulation of folds, plaque-like deformities • High- or low-grade SB obstruction, usually due to fibrosis, rarely intussusception

Meckel Diverticulum • Most frequent congenital anomaly of GI tract • Ileal outpouching (~ 2 feet from ileocecal valve) • May cause SB obstruction or intussusception ○ SB spasm due to Meckel diverticulitis ○ Diverticulum "inverted" into bowel lumen may cause intussusception

PATHOLOGY General Features • Etiology ○ Most adult intussusceptions are short segment, transient, nonobstructing, not associated with lead mass – Idiopathic or underlying SB disorder (e.g., celiac-sprue) – Intussusception in children is much more common, and usually attributed to lymphoid hyperplasia within bowel wall ○ Tumor-related lead point: Benign and malignant masses 399

Small Intestine

Intussusception

○

○ ○ ○

– Benign: More common in SB □ Polyps such as lipoma, leiomyoma – Malignant □ Carcinoma: Much more common in colocolic intussusception □ GIST, carcinoid, others – Metastases and lymphoma □ More common in SB intussusception Postoperative risk factors (more common in SB) – Suture lines, ostomy closure sites – Adhesions, long intestinal tubes – Bypassed intestinal segments – Appendiceal stump granuloma – Abnormal bowel motility, electrolyte imbalance – Chronic dilated loop Meckel diverticulum; celiac and Whipple diseases Colitis (usually infectious) Epiploic appendagitis

Staging, Grading, & Classification • Short-segment, nonobstructing intussusception ○ Usually self-limited, without lead mass • Long-segment, obstructing intussusception; mass is more likely

Gross Pathologic & Surgical Features • 3 layers seen ○ Intussusceptum: Entering/inner tube and returning/middle tube ○ Intussuscipiens: Sheath or outer tube

Treatment • None for transient, nonobstructing intussusception • Resection for ileocolic, ileocecocolic, and colocolic • Children: Hydrostatic or pneumatic reduction ○ Surgical reduction or resection usually reserved for complicated cases (e.g., with bowel ischemia)

DIAGNOSTIC CHECKLIST Consider • Short-segment, nonobstructing intussusceptions are common in adults; no treatment required

Image Interpretation Pearls • Barium fluoroscopy ○ "Coiled spring" appearance due to barium between intussusceptum and intussuscipiens ○ Lead point: Lobulated mass etched in white • CT: Bowel-within-bowel ○ Alternating layers of bowel walls, mesenteric fat and vessels

SELECTED REFERENCES 1. 2. 3.

Microscopic Features

4.

• Early: Inflammatory changes • Late: Ischemic necrosis, mucosal sloughing

5.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Adults: Intermittent pain, vomiting, red blood in stool ○ Children: Acute pain, palpable oblong abdominal mass; "red currant jelly" stools

Demographics • Age ○ Any age group; children > adults • Gender ○ M=F • Epidemiology ○ Uncommon in adults, much more common in children – 95% of all intussusceptions occur in children – 2nd most common cause of acute abdomen in children □ Idiopathic in 90% of cases □ Often attributed to lymphoid hyperplasia in SB wall

Natural History & Prognosis • Complications: Obstruction, infarction, hemorrhage, perforation, peritonitis • Prognosis ○ Early: Good after reduction or surgical resection; recurrence very rare 400

○ Late: Poor due to risk of severe vascular compromise, gangrene, perforation

6. 7. 8. 9. 10. 11. 12. 13. 14.

15. 16. 17.

Mitchell A et al: Coeliac disease in an adult presenting as intussusception without a lead point. BMJ Case Rep. 2014, 2014 Potts J et al: Small bowel intussusception in adults. Ann R Coll Surg Engl. 96(1):11-4, 2014 Lianos G et al: Adult bowel intussusception: presentation, location, etiology, diagnosis and treatment. G Chir. 34(9-10):280-3, 2013 El Fortia M et al: Tetra-layered sign of adult intussusception (new ultrasound approach). Ultrasound Med Biol. 32(4):479-82, 2006 Henry MC et al: The appendix sign: a radiographic marker for irreducible intussusception. J Pediatr Surg. 41(3):487-9, 2006 Mateen MA et al: Transient small bowel intussusceptions: ultrasound findings and clinical significance. Abdom Imaging. 2006 Grosfeld JL: Intussusception then and now: a historical vignette. J Am Coll Surg. 201(6):830-3, 2005 Kim KH et al: Intussusception after gastric surgery. Endoscopy. 37(12):123743, 2005 Ouyang EC et al: Ileocolonic intussusception. MedGenMed. 7(3):15, 2005 Huang BY et al: Adult intussusception: diagnosis and clinical relevance. Radiol Clin North Am. 41(6):1137-51, 2003 Lvoff N et al: Distinguishing features of self-limiting adult small-bowel intussusception identified at CT. Radiology. 227(1):68-72, 2003 Saenz De Ormijana J et al: Idiopathic enteroenteric intussusceptions in adults. Abdom Imaging. 28(1):8-11, 2003 Gayer G et al: Pictorial review: adult intussusception--a CT diagnosis. Br J Radiol. 75(890):185-90, 2002 Fujimoto T et al: Unenhanced CT findings of vascular compromise in association with intussusceptions in adults. AJR Am J Roentgenol. 176(5):1167-71, 2001 Warshauer DM et al: Adult intussusception detected at CT or MR imaging: clinical-imaging correlation. Radiology. 212(3):853-60, 1999 Catalano O: Transient small bowel intussusception: CT findings in adults. Br J Radiol. 70(836):805-8, 1997 Lorigan JG et al: The computed tomographic appearances and clinical significance of intussusception in adults with malignant neoplasms. Br J Radiol. 63(748):257-62, 1990

Intussusception Small Intestine

(Left) Axial CECT in a patient with ileocolic intussusception shows an outer ring intussuscipiens of the colon wall, while the intussusceptum is a small intestinal segment . Mesenteric fat and vessels accompany the intussuscepted small bowel (SB) segment. (Right) Axial CECT shows a reniform (kidney-shaped) SB due to jejunal intussusception. Note the intussuscepted mesenteric fat and vessels .

(Left) Axial CT shows an intussusceptum with its mesenteric fat within the contrast opacified lumen of the ascending colon, the intussuscipiens in this case. (Right) Axial CT in the same case shows that the lead mass of the intussusception is a lowdensity, spherical mass with a calcified rim, a characteristic appearance of an appendiceal mucocele. Long-segment, obstructing intussusceptions such as this often have a lead mass when seen in adults.

(Left) Coronal CT image in the same case shows the longsegment intussusception and the mucocele as the lead mass. (Right) The resected specimen in the same case, consisting of the terminal ileum and ascending colon, shows the mucocele of the appendix and the intussusception .

401

Small Intestine

Malabsorption Conditions KEY FACTS

IMAGING • Dilated small bowel (SB) with fold thickening, mucosal nodularity or ulceration, motility changes, increased luminal fluid • Imaging findings often suggest malabsorption, but specific diagnosis is difficult

PATHOLOGY • Classification of malabsorption by etiology • Maldigestion ○ Chronic pancreatitis, cholestasis, ileal resection • Malabsorption at mucosal level ○ Celiac disease, Crohn, tropical sprue ○ Short bowel, cystic fibrosis ○ Eosinophilic gastroenteritis, Whipple disease ○ Amyloidosis, hypogammaglobulinemia, mastocytosis • Malassimilation ○ Primary and secondary lymphangiectasia ○ Lipoproteinemia

(Left) Small bowel (SB) follow through in a 56-year-old man with adult onset of malabsorption condition illustrates segments of jejunum that are featureless and devoid of valvulae conniventes, reminiscent of normal loops of ileum. (Right) Small bowel follow-through in the same patient demonstrates the ileum to have a fold pattern reminiscent of the normal jejunum . This reversal of the fold pattern is characteristic of adult celiac disease.

(Left) Axial CECT in a 61-yearold man with chronic diarrhea and recent weight loss shows marked dilation of the duodenal and jejunal lumen with a very diminished fold pattern. (Right) Axial CECT in the same patient conversely illustrates abnormally prominent ileal folds , the "fold reversal" pattern characteristic of celiac-sprue. Focal segmental luminal spasm and dilation are also evident, along with excess fluid within the SB.

402

• Malabsorption caused by bacterial overgrowth ○ Idiopathic pseudoobstruction, systemic sclerosis ○ Multiple, large, SB diverticula

CLINICAL ISSUES • Most common signs/symptoms ○ Diarrhea, steatorrhea, flatulence ○ Abdominal distension, weight loss, anemia • Diagnosis: Mucosal biopsy and histology • Celiac-sprue is most common SB disease producing malabsorption • Treatment ○ Celiac: Gluten-free diet ○ Tropical sprue: Antibiotics ○ Crohn disease: Steroids, azathioprine, mesalamine; surgical resection

Gallstone Ileus

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Mechanical bowel obstruction due to impacted gallstones

• Intussusception • Dropped gallstone (intraperitoneal, not intraluminal)

IMAGING • Best diagnostic clue ○ Rigler triad of small bowel (SB) obstruction, gas in biliary tree, and ectopic gallstone • Location: Points of luminal narrowing of bowel; duodenum, ligament of Treitz, ileocecal valve, sigmoid colon • CT findings ○ Gallstone surrounded by gas in bowel loop – Cholesterol stones near-water density, often with calcified rim ○ Collapsed gallbladder, pneumobilia (gas within GB ± bile duct lumen) ○ Dilated bowel with transition to collapsed bowel at impacted gallstone

PATHOLOGY

Small Intestine

KEY FACTS

• Occurs with chronic cholecystitis • Delayed (up to 2 months) complication of ERCP • Diagnosis frequently delayed or missed

CLINICAL ISSUES • Most common signs/symptoms: Intermittent acute colicky abdominal pain (20-30%), nausea, vomiting, fever, distension, obstipation • Gallstone erodes inflamed GB wall, passes into GI tract (usually duodenum) bowel obstruction

DIAGNOSTIC CHECKLIST • Consider in elderly woman with recurrent RUQ pain, recently more severe and prolonged vomiting

(Left) Axial CECT in a 65-yearold woman presenting with crampy abdominal pain demonstrates a thick-walled gallbladder with air within its lumen and a gas-filled fistula to the duodenum . (Right) Axial CECT in the same patient identifies the obstructing gallstone , which is impacted in the distal jejunum. The proximal small bowel is dilated, while the distal SB and colon are collapsed.

(Left) Axial CECT in a patient presenting with bloating and abdominal pain demonstrates gas in the gallbladder , a typical finding in gallstone ileus, also known as gallstone obstruction. (Right) Axial CECT in the same patient demonstrates dilation of the proximal small bowel and decompressed, nondilated distal small bowel . The high-density obstructing gallstone is seen, as a laminated calcification, at the site of transition from the dilated to the decompressed bowel.

403

Small Intestine

Enteric Fistulas and Sinus Tracts KEY FACTS

TERMINOLOGY • Enteric fistula: Abnormal connection between bowel and another epithelial-lined surface (e.g., bladder, vagina, skin) • Enteric sinus tract: Blind-ending tract originating from bowel

IMAGING • MR considered best modality for perianal fistulas ○ Perianal fistula in active setting usually T2 hyperintense, T1 hypointense and enhancing on T1 C+ MR ○ Parks classification of perianal fistulas – Intersphincteric fistula: Fistula traverses internal anal sphincter and extends downwards to skin surface – Transsphincteric fistula: Fistula traverses both internal and external anal sphincters – Extrasphincteric fistula: Fistula extends from supralevator space into ischioanal fossa without involving sphincter complex

(Left) Graphic illustration of the perianal region demonstrates the 4 different types of perianal fistulas in the Parks classification and their relationship to the internal/external anal sphincters and the levator musculature. (Right) Axial T2 FS MR demonstrates a linear T2 hyperintense fistulous track in the intersphincteric space. The track is outside the internal sphincter, but does not cross the external sphincter, compatible with an intersphincteric perianal fistula.

(Left) Axial T1 C+ FS MR demonstrates enhancement along the track of a transsphincteric perianal fistula arising from the anal canal at the 5-o'clock position. Enhancement along fistulous tracts suggests that the fistula is active, rather than chronic and healed. (Right) Coronal T1 C+ FS MR demonstrates a transsphincteric fistula with an internal low signal seton catheter . Seton catheters, often utilized to keep fistulous tracts open and facilitate drainage, appear low signal on all pulse sequences.

404

– Suprasphincteric fistula: Fistula crosses internal sphincter, rises into supralevator space, and then crosses into ischioanal fossa • Fistulogram probably best modality for definition of enterocutaneous fistulas • Other fluoroscopic studies may have utility depending on location of fistulas (e.g., water soluble contrast enema for colovesical and colovaginal fistulas) • CT: Detection of fistulas requires attention to both primary (e.g., direct fistulous tract filled with ectopic gas or contrast) and secondary (e.g., ectopic gas, abnormally tethered bowel loops) signs

CLINICAL ISSUES • Symptoms dependent on type of fistula ○ Perianal fistulas most commonly present with purulent discharge or local pain and inflammation ○ Enterocutaneous fistulas often result in infected wound with purulent drainage

Enteric Fistulas and Sinus Tracts

Definitions • Enteric fistula: Abnormal connection between bowel and another epithelial-lined surface (e.g., bladder, vagina, skin) • Enteric sinus tract: Blind-ending tract originating from bowel • Perianal fistula: Abnormal communication between anal canal and surrounding soft tissues or skin surface

IMAGING General Features • Best diagnostic clue ○ Presence of discrete enhancing tract connecting bowel and another epithelial-lined surface ○ Presence of unexpected gas, debris, or enteric contrast medium within bladder, vagina, etc.

Imaging Recommendations • Best imaging tool ○ MR considered best modality for perianal fistulas and sinus tracts due to superior soft tissue resolution and ability to discriminate different anatomic components of perianal region – CECT is probably better cross-sectional modality for many other locations due to superior spatial resolution ○ Fluoroscopic small bowel follow-through or contrast enema may be best choice for demonstrating internal (e.g., gut-to-gut) fistulas between bowel loops ○ Fistulogram for definition of enterocutaneous fistulas • Protocol advice ○ CECT: Consider use of oral, rectal, or IV contrast media – Not always advisable to use all at once, as this may confuse origin of opacified lumen

MR Findings • MR now considered imaging modality of choice for evaluation of perianal fistulas ○ Fistulous tracts in this region often not visible on CT due to limited soft tissue resolution ○ MR can determine relationship of fistulous tract with anal sphincters, identify exact site of opening of fistulous tract in anal canal, and differentiate fistulas which arise from distal rectum from those that arise from anal canal ○ MR proven to be very accurate, with sensitivity of 97% and specificity of 100% for detection of fistulas ○ Possible that MR at 3T may offer advantages in delineating fistulas due to superior signal-to-noise ratio and improved spatial resolution – Pelvic surface coils often utilized, but endorectal coil typically not necessary • MR protocol design (for perianal fistulas) ○ High resolution T2-weighted images through perianal region are critical to diagnosis – Images must be appropriately oriented perpendicular and parallel to anal canal □ Images oriented using localizer images through pelvis

– Typically fat saturation (either frequency-selective fat saturation or inversion recovery/STIR) included in at least 1 plane □ STIR images have advantage of less susceptibility artifact from sutures □ Fistulas and sinus tracts typically are T2 hyperintense and are more conspicuous with fat saturation □ T2 weighted images without fat saturation helpful to better identify sphincter anatomy, although fistulous tracts may be more difficult to visualize – High-resolution 3D T2-weighted images (i.e., T2 SPACE) are increasingly utilized to provide more precise delineation of fistulous tracts □ 3D images can be reconstructed into any plane due to isotropic voxel size, but at expense of longer acquisition time – Post-contrast T1 weighted images also included, as active fistulous tracts typically show enhancement – DWI may help in tract identification, but carries no other prognostic significance • MR findings of perianal fistulas ○ Fistulous tracts are usually T2 hyperintense and T1 hypointense and originate from anal canal – Site of origin of fistula described using clock face, which corresponds to surgeon's view of perianal region in lithotomy position □ 6-o'clock is posterior, 12-o'clock is anterior, 3o'clock is to patient's left, and 9-o'clock is to patient's right ○ Active fistulas typically show enhancement on T1 C+ images, while old, healed fistulous tracts do not – Old, healed fibrotic fistulas usually hypointense on both T1 and T2WI ○ Abscesses appear as focal collections of T2 bright fluid which demonstrate peripheral enhancement on T1 C+ images ○ Secondary fistulous tracts or ramifications are common and can impact treatment ○ Seton catheters placed in fistula tracts typically appear as thin, curvilinear structures which are low signal on all pulse sequences • Classification of perianal fistulas ○ Parks classification based primarily on surgical findings and secondarily applied to MR – Intersphincteric fistula (45% of cases): Fistula traverses internal anal sphincter and extends downwards to skin surface (no involvement of external sphincter) □ Fistula completely confined within intersphincteric space (between internal and external sphincters) – Transsphincteric fistula (30% of cases): Fistula traverses both internal and external anal sphincters before extending through ischioanal fossa to skin surface – Extrasphincteric fistula (5% of cases): Fistula extends from supralevator space across levator complex into ischioanal fossa without involving sphincter complex □ Usually caused by primary pelvic inflammation (e.g., Crohn disease, pelvic abscess, rectal cancer, diverticulitis, etc.)

Small Intestine

TERMINOLOGY

405

Small Intestine

Enteric Fistulas and Sinus Tracts

– Suprasphincteric fistula (20% of cases): Fistula crosses internal sphincter, rises upward into supralevator space, and then crosses over levator complex into ischioanal fossa ○ St. James University Hospital classification (based primarily on MR findings) – Grade I: Simple intersphincteric fistula without secondary tracts or abscess – Grade II: Intersphincteric fistula with abscess or secondary tract – Grade III: Transsphincteric fistula without secondary tracts or abscess – Grade IV: Transsphincteric fistula with secondary tracts or abscess – Grade V: Fistula with supralevator or translevator involvement (suprasphincteric or extrasphincteric fistulas) – Direct correlation between MR grade of fistula and clinical outcomes: Higher grades associated with worse outcomes ○ Sinus tracts (not described in either classification system): Superficial tracts which do not communicate with anal canal ○ Submucosal fistulas (not described in either classification system): Superficial tracts arising from inferior anal canal which extend to skin surface without involving internal or external sphincters

Fluoroscopic Findings • Upper GI ○ More useful for duodenal fistulas, but generally less useful for small bowel ○ May be helpful to demonstrate enteroenteric fistulas, but can be difficult to detect without high index of suspicion on part of radiologist – Unlike fistulograms, provide global view of GI tract which may help surgical planning – May not identify fistula if contrast moves too rapidly, patient cannot ingest sufficient contrast, or if fistula is located distally and previously opacification of loops of bowel makes it difficult to identify fistula • Contrast enema ○ Water soluble contrast enema may demonstrate colovesical and colovaginal fistulas ○ Better than upper GI for demonstrating fistulas that involve colon due to increased intraluminal pressures • Fistulagram ○ Injection of contrast via catheter placed into cutaneous fistula opening – Defines presence and location of communication to gut – Important to depict specific site of connection, as proximal bowel involvement causes more fluid and electrolyte losses and is usually associated with greater morbidity – Greater sensitivity for enterocutaneous fistulas compared to small bowel follow-through – Provides only limited information about disease upstream or downstream from enterocutaneous fistula and may need to be supplemented by CT or small bowel follow-through 406

CT Findings • Gut-to-gut fistula (e.g., enteroenteric, enterocolic, colocolic) ○ Can be difficult to reliably identify on cross-sectional imaging, although discrete tract filled with enteric contrast or gas may sometimes be visualized ○ Enteric contrast may not consistently fill fistula depending on amount of contrast ingested, speed of contrast transit through bowel, size of fistula, etc. • Enterocutaneous fistula ○ May be difficult to demonstrate with certainty on CT, particularly if discrete gas or contrast filled tract is not identified – Administration of positive oral contrast may be helpful, but may not always fill fistulous track ○ Involved bowel loops often thickened and tethered to anterior abdominal wall in close contiguity to ectopic gas within abdominal wall • Colovesical fistula to thick-walled bladder ○ Should be suspected in presence of gas, debris, or rectal contrast material within bladder even if direct track is not visible ○ Bladder wall may appear focally thickened at site of contact between inflamed colon and bladder ○ Most often occur at dome of bladder • Colovaginal fistula should be suspected in presence of gas, debris, or contrast within vagina • Diverticulitis with fistula ○ Wall thickening, luminal narrowing and pericolonic inflammation (± ectopic gas) in site with multiple diverticula (usually sigmoid colon) ○ Can result in fistulas between colon and bladder, vagina, or other bowel loops • Pancreatitis with fistula ○ Most often due to necrotizing pancreatitis, with sinus tracts possible between pancreatic duct and skin, bowel, or left pleural space • Crohn disease with fistula ○ Strong tendency to form fistulous tracts (e.g., to other small bowel loops, colon, skin, bladder, vagina) or sinus tracts into mesenteric fat ○ Perianal fistulas and abscesses are common ○ Even if direct fistulous tracts are not visible, presence of ectopic gas in mesentery with surrounding thickened, tethered loops of inflamed small bowel should raise concern for "complex fistulizing Crohn disease" (e.g., multiple complex interloop fistulas and sinus tracts) • Duodenal fistula ○ May result from peptic ulcer disease, sphincterotomy, gastric resection, or gallstone erosion

PATHOLOGY General Features • Etiology ○ Spontaneous (nonsurgical) causes – Diverticulitis: Most common cause of fistulization in industrialized countries – Crohn disease: Accounts for 20-30% of all enterocutaneous fistulas

Enteric Fistulas and Sinus Tracts

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Symptoms dependent on type of fistula and bowel segment involved ○ Enterocutaneous fistulas often present with fever, abdominal pain, distension, and drainage from wound (with signs of wound infection) ○ Other symptoms include sepsis, pneumaturia (colovesical fistula), feces per vagina (rectovaginal fistula), diarrhea (due to fistulization to distal colon), bowel obstruction (due to inflammation from fistula), or gastrointestinal bleeding ○ Perianal fistulas most commonly present with purulent discharge (2/3 of cases) or local pain and inflammation ○ High output enterocutaneous fistulas (i.e., duodenal stump leak) may cause major electrolyte loss and more often originate in upper GI tract – Lower output fistulas arise more distally

Demographics • Epidemiology ○ Perianal fistulas most common in young males (M:F = 2:1) – Perianal fistulas very uncommon, with prevalence of only 0.01% ○ 33% of Crohn disease patients develop fistulas after 10 years; 50% after 20 years

Small Intestine

– Other causes include bowel perforation, malignancy, or infections ○ Surgical causes – Probably represents most common cause; usually result from bowel injury during surgery, including inadvertant enterotomy, anastomotic leak, or erosion of foreign body into bowel □ Associated risk factors: Malnutrition, infection, immunosuppression, radiation therapy, or emergent surgical procedure – Abdominoperineal or low anterior resection (LAR) for rectal cancer is especially prone to anastomotic leak and development of fistulas □ Commonly associated with fistulas to vagina (510% of women after LAR) – Hysterectomy associated with increased risk of fistula when performed for endometrial or cervical carcinoma □ Radiation therapy or coexisting diverticulitis increases risk of colovaginal or rectovaginal fistula ○ Radiation: Associated with rectovaginal fistula ○ Perianal fistulas – 90% are idiopathic and arise due to impaired drainage of anal glands leading to infection and subsequent development of perianal abscess or fistula □ Inadequately treated abscesses often result in development of fistula, explaining high incidence of both abscess and fistula in same patient (~ 90% with perianal abscess go on to develop fistula) – Other causes account for remaining 10% of cases □ Crohn disease (incidence of ~ 25% after 20 years of disease) □ Diverticulitis □ Tuberculosis □ Trauma □ Anorectal cancer □ Radiation treatment □ Sequelae of other pelvic infections (e.g., actinomycosis, lymphogranuloma venereum, etc.) □ Childbirth □ HIV/AIDS

Treatment • Fluid support, correction of electrolyte abnormalities, and antibiotics to treat underlying infection ○ Presence of discrete abscess associated with fistula may require percutaneous drainage • Enterocutaneous fistulas may close spontaneously with bowel rest, IV fluids, parenteral nutrition, ± somatostatin • Internal gut-to-gut fistulas involving small or large bowel loops do not typically close spontaneously and often require surgical correction • Colovesical/colovaginal fistulas usually require surgical repair ○ Colostomy to divert fecal stream, followed by fistula excision (either open or percutaneous technique) • Perianal fistulas in patients with idiopathic fistulas usually surgically managed ○ Fistulotomy or fistulectomy of tracts and drainage of abscesses ○ Preoperative knowledge of fistula's relationship with sphincter complex is critical for preservation of continence – Internal sphincter can generally be divided without loss of continence – External sphincter division can lead to incontinence ○ Combination of medical and surgical therapy utilized to treat fistulas due to Crohn disease ○ Setons (thread placed in fistulous track during fistula incision) can keep fistula open and allow continuous drainage ○ Fibrin glue and omentoplasty also represent treatment options

DIAGNOSTIC CHECKLIST Consider • MR is far superior to CT in identification of perianal fistulas and abscesses, as well as classifying fistula's relationship with anal sphincters and levator complex

Image Interpretation Pearls • Active perianal fistulas demonstrate high signal on T2WI and enhancement on T1 C+ MR, whereas old, healed fistulas are nonenhancing with low signal on T1 and T2WI

SELECTED REFERENCES 1.

2.

Amiot A et al: Long-term outcome of enterocutaneous fistula in patients with Crohn's disease treated with anti-TNF therapy: a cohort study from the GETAID. Am J Gastroenterol. 109(9):1443-9, 2014 de Miguel Criado J et al: MR imaging evaluation of perianal fistulas: spectrum of imaging features. Radiographics. 32(1):175-94, 2012

407

Small Intestine

Enteric Fistulas and Sinus Tracts

(Left) Axial T1 C+ FS MR in a patient with Crohn disease demonstrates avid enhancement and thickening of the rectum, compatible with Crohn colitis. Note the fistulous track arising from the rectum above the levator muscle complex. (Right) Coronal T1 C+ FS MR in the same patient nicely demonstrates the extrasphincteric fistula in this patient arising in the supralevator space and directly crossing the levator muscle complex into the ischioanal fossa without involving the anal sphincters.

(Left) Axial T2 MR demonstrates a large transsphincteric perianal fistula crossing the external sphincter and extending into the posterior soft tissues on the left. Notice that the fistula is contiguous with a large T2 hyperintense "horseshoe" type abscess in the intersphincteric space. (Right) Axial T1 C+ FS MR in the same patient demonstrates the prominent rim enhancement associated with both the abscess and the fistula .

(Left) Coronal T1 C+ FS MR demonstrates an enhancing fistulous track rising upward from the intersphincteric space into the supralevator space, before crossing the levator ani muscle complex, compatible with a suprasphincteric fistula. (Right) Axial T1 C+ FS MR in a patient with rectal cancer demonstrates a sinus track extending posteriorly at the 6o'clock position into the presacral space.

408

Enteric Fistulas and Sinus Tracts Small Intestine

(Left) Axial CECT shows sigmoid colonic mucosal hyperenhancement, submucosal edema , and pericolonic infiltration in a 54year-old woman with a long history of Crohn disease who developed foul-smelling vaginal discharge. (Right) More caudal axial CECT section in the same patient shows extensive rectal and perirectal inflammation .

(Left) Axial CECT section in the same patient through the low rectum shows severe inflammation and the enhancing walls of a fistulous tract extending toward the vagina. (Right) Spot film from a water soluble contrast enema in the same case shows opacification of the rectosigmoid colon and the vagina through a fistulous tract starting low in the rectum. Contrast spilling out of the anus and vagina stains the overlying sheets.

(Left) After removing the soiled sheets, a repeat film from the contrast enema in the same patient shows contrast medium within the rectum , vagina , and fistula . (Right) Lateral film from the contrast enema in the same patient shows the contrast-opacified lumens of the rectum and vagina . Crohn disease is a common cause of spontaneous enteric fistulas, as it is a chronic, transmural inflammatory disease.

409

Small Intestine

Enteric Fistulas and Sinus Tracts

(Left) Axial CECT shows extensive diverticulosis in an elderly woman who presented with urinary sepsis and high fever. The colonic lumen is opacified by rectal contrast medium. (Right) Axial NECT in the same patient shows a thick-walled urinary bladder that is filled with gas, particulate (fecal) debris, and rectally administered contrast medium , confirming a colovesical fistula. Diverticulitis was confirmed as the etiology.

(Left) Axial CECT following rectal contrast administration shows a thick-walled sigmoid colon in a 60-year-old woman who had undergone a prior hysterectomy and developed foul-smelling vaginal discharge. (Right) Axial CECT in the same patient shows adherence of the anterior rectal wall to the back wall of the vagina or cervix .

(Left) Axial CECT in the same patient shows rectally administered contrast medium within the vagina , confirming a colovaginal fistula. (Right) Sagittally reformatted CECT section in the same patient shows the fistula from the distal colon (or rectum) to the vagina (or cervix) . Diverticulitis and hysterectomy are both associated with colovaginal fistula.

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Enteric Fistulas and Sinus Tracts Small Intestine

(Left) Axial CECT of a 29-yearold woman with chronic, intermittent abdominal pain and perianal inflammation shows part of a long segment of thick-walled ileum , mucosal hyperenhancement, and extraluminal gas and fluid . (Right) Axial CECT in the same patient shows a fistula extending from the low rectum or anus toward the skin. These are characteristic features of Crohn disease. Please note that CT is far inferior to MR in both the identification and classification of perianal fistulas.

(Left) Axial CECT of a morbidly obese young woman with pain and a foul-smelling discharge from a cutaneous site shows a walled-off abscess adjacent to the sigmoid colon. There is a tract of gas and fluid leading to the anterior abdominal wall defect. (Right) Fistulagram (injection of a catheter inserted into the abdominal wall defect), in the same patient, opacifies an abdominal abscess cavity and the sigmoid colon lumen . Diverticulitis was the etiology of this spontaneous colocutaneous fistula.

(Left) Sagittal CECT in a patient with a history of diverticulitis and purulent vaginal drainage demonstrates a fistulous communication between the sigmoid colon and uterus near the fundus. (Right) Coronal CECT demonstrates several signs of a colovesical fistula in this patient with acute diverticulitis , including direct contact between the inflamed colon and the bladder, focal wall thickening of the bladder at the site of contact, and the presence of ectopic gas within the bladder lumen.

411

Small Intestine

Ischemic Enteritis KEY FACTS

IMAGING

PATHOLOGY

• Best diagnostic clue ○ Clot or narrowing of superior mesenteric artery or superior mesenteric vein with bowel wall thickening • Best imaging tool ○ MDCT with CT angiography; multiplanar reformations ○ Catheter angiography for diagnostic confirmation and treatment

• Vascular occlusion: Embolic events (atrial fibrillation, endocarditis), thrombotic events (atherosclerosis), mechanical obstruction (strangulation, tumor) • Closed-loop obstruction is especially dangerous

TOP DIFFERENTIAL DIAGNOSES • • • • •

Intestinal (angioneurotic) angioedema Small intestine vasculitis Shock bowel Crohn disease Fibrosing mesenteritis

(Left) Graphic shows a dilated small bowel (SB) with thickened wall, ascites, and edematous mesentery, all findings seen with occlusion of the superior mesenteric vein. (Right) Axial CECT in an elderly woman with abdominal pain demonstrates dilated small bowel with pneumatosis . Portal venous gas was also present on other sections (not shown). Infarcted bowel was confirmed at surgery, and the patient died.

(Left) Oblique film from small bowel follow-through reveals luminal narrowing and a loss of normal small bowel fold pattern in the ileum , as well as dilation of the more proximal segments . (Right) Superior mesenteric angiogram in the same patient illustrates a cutoff of some of the ileal branches of the superior mesenteric artery (SMA) with a lack of blood flow to the ileum. This appearance suggests an embolic source, as thrombosis would tend to involve the origin of the SMA.

412

CLINICAL ISSUES • Most common signs/symptoms ○ Acute ischemia: Clinical triad of sudden-onset abdominal pain, diarrhea, and vomiting • Surgical treatment: Exploratory laparotomy, bowel resection, and mesenteric bypass to reestablish blood flow

DIAGNOSTIC CHECKLIST • Imaging findings vary due to many factors (e.g., acute vs. chronic; arterial vs. venous) • Mesenteric venous occlusion causes more impressive wall thickening, mesenteric infiltration, and ascites than arterial occlusion

Ischemic Enteritis

Synonyms • Acute mesenteric ischemia

Definitions • Mesenteric arterial or venous narrowing or occlusion, leading to inadequate supply of nutrients and oxygen to small bowel (SB)

IMAGING General Features

○

collateral arteries

Imaging Recommendations • Best imaging tool ○ MDCT with CT angiography – Makes arterial or venous occlusion more apparent and quantifiable – Lung window setting for pneumatosis intestinalis ○ Catheter angiography – Diagnostic confirmation and treatment

DIFFERENTIAL DIAGNOSIS

• Best diagnostic clue ○ Clot or narrowing of superior mesenteric artery (SMA) or superior mesenteric vein (SMV) with bowel wall thickening

Intestinal (Angioneurotic) Angioedema

Radiographic Findings

Small Intestine Vasculitis

• Radiography ○ Multiple air-fluid levels; ileus pattern ○ Thickening of valvulae conniventes ○ Linear distribution of gas (pneumatosis intestinalis)

• Segmental bowel wall thickening • Submucosal edema, target sign • May not be distinguishable on imaging alone

Fluoroscopic Findings • Barium studies ○ Thickening of valvulae conniventes ○ "Thumbprinting" pattern: Intramural accumulation of blood distending submucosa focally rounded mesenteric folds, especially along mesenteric border ○ "Stack of coins" pattern: Enlarged, smooth, straight, parallel folds perpendicular to longitudinal axis of SB (submucosal edema) ○ Strictures often seen with proximal bowel dilation ○ Mottled, frothy, bubbly, or linear collections of gas in bowel wall (pneumatosis intestinalis)

• Hereditary or drug induced (e.g., ACE inhibitors) • Causes massive bowel wall edema, ascites; indistinguishable from ischemia on imaging

Shock Bowel • Ischemia ± reperfusion of SB, usually following trauma or other cause of hypotension • Intense mucosal enhancement, edema of submucosa and mesentery • Reversible with resuscitation

Crohn Disease • Usually affects distal SB • Asymmetric, discontinuous, thickened bowel wall, proliferation of mesenteric fat • Focal, inflammatory, mucosal ulceration and patchy submucosal fibrosis distortion and interruption of folds

CT Findings

Fibrosing Mesenteritis

• CECT ○ Clot or reduced lumen in SMA, SMV, or other mesenteric vessels ○ Segmental thickening of bowel wall (> 3 mm) ○ Emboli usually observed at origin of SMA or 3-10 cm from SMA distal to middle colic artery ○ Lack of bowel mucosal enhancement due to compromised arterial flow ○ "Misty" mesentery: Mesenteric fat infiltrated by edema; more common with venous thrombosis ○ attenuation of bowel wall due to submucosal hemorrhage or hyperemia – More common in venous than arterial thrombosis ○ Pneumatosis intestinalis (venous > arterial thrombus) – Band-like or bubble-like appearance in bowel wall – Linear, curvilinear, or cystic gas-filled spaces – ± gas in mesenteric or portal vein – Fluid-distended bowel loops

• Bowel wall thickening uncommon, due to fibrotic constriction of mesenteric veins and lymphatics • "Misty" mesentery appearance, fat halo surrounding but not displacing mesenteric vessels • Mesenteric nodes ± soft tissue mass (advanced)

Angiographic Findings • • • •

Acute arterial ischemia: Clot/stenosis of SMA or branches Acute venous ischemia: SMV occlusion with collaterals Nonocclusive ischemia: Slow flow in SMA Chronic ischemia: Narrowing/occlusion of celiac artery &/or SMA

Small Intestine

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ Vascular occlusion: Embolic events (atrial fibrillation, endocarditis), thrombotic events (atherosclerosis), mechanical obstruction (strangulation, tumor) ○ Closed-loop obstruction especially dangerous ○ Hypercoagulable states: Oral contraceptives, protein C deficiency, factor V Leiden deficiency ○ Inflammatory: Pancreatitis, peritonitis, vasculitis – Vasculitis: Common cause of ischemia in younger patients – Systemic lupus erythematosus, polyarteritis nodosa, other collagen vascular diseases – Vasculitis may affect kidneys and other organs ○ Iatrogenic causes: Radiation and chemotherapy, therapeutic drugs (digitalis, dopamine, vasopressin), illicit drugs (heroin, cocaine, amphetamines) 413

Small Intestine

Ischemic Enteritis ○ Hypoperfusion (more common in ischemic colitis): Lowflow states, hypotension, sepsis, heart failure

– Depends on promptness of diagnosis, amount of salvageable SB – 50-90% mortality – Outcomes in venous ischemia patients are generally better ○ Chronic – Survival dependent on degree of collateral circulation – Diagnosis requires occlusion of 2 major mesenteric arteries and narrowing of 3rd artery ○ Infarction: 69% mortality (in recent series)

Staging, Grading, & Classification • Classification ○ Acute occlusive ischemia (arterial or venous) ○ Acute nonocclusive ischemia (e.g., shock) ○ Chronic ischemia: Older "vasculopaths," atherosclerosis

Gross Pathologic & Surgical Features • Discolored (purple), infarcted SB

Microscopic Features

Treatment

• Necrotic, inflammatory, or ischemic features in SB wall

• Surgical treatment ○ Exploratory laparotomy, bowel resection, and mesenteric bypass to reestablish blood flow ○ Main treatment for acute ischemia, chronic ischemia, and complications • Endovascular intervention ○ Intraarterial thrombolysis, percutaneous transluminal angioplasty ± stent placement ○ Thrombolytics (streptokinase, urokinase) ○ Vasodilators (papaverine) to reduce vasospasm • Systemic anticoagulation (warfarin, heparin) for venous occlusion

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute ischemia – Clinical triad: Sudden onset of abdominal pain, diarrhea, vomiting – Unremitting abdominal pain disproportionate to physical exam findings – Abdominal distention, tenesmus, passage of bloody stool – Guarding and rebound (infarction/perforation) – Venous ischemia has more gradual onset ○ Chronic ischemia – Intestinal angina: Postprandial abdominal pain subsiding 1-2 hours after meal – Nausea, vomiting, diarrhea, weight loss – Intense pain fear of eating (sitophobia) ○ Lab data – WBC in 75% of cases, acidosis in 50% of cases, amylase in 25% of cases ○ Diagnosis – High clinical suspicion is key to early diagnosis

Demographics • Age ○ Majority > 50 years old • Gender ○ M=F • Epidemiology ○ Accounts for 1% of acute abdomen cases ○ Risk factors of chronic ischemia include hypertension, coronary artery disease, cerebrovascular disease ○ Arterial > venous occlusive ischemia (9:1) ○ 60-70% of acute ischemia due to arterial occlusion, 510% due to venous occlusion ○ 20-30% of acute ischemia is nonocclusive

Natural History & Prognosis • Complications: Stricture, infarction, necrosis, perforation • Late-phase ischemia can lead to diffuse or localized pneumatosis intestinalis • Imaging findings vary: Acute vs. chronic, arterial vs. venous thrombosis • Prognosis ○ Acute

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DIAGNOSTIC CHECKLIST Consider • SB ischemia is a clinicoradiological diagnosis • Consult referring physician for history, symptoms, key lab values (acidosis, leukocytosis)

Image Interpretation Pearls • Imaging findings vary due to many factors (e.g., acute vs. chronic; arterial vs. venous) • Mesenteric venous occlusion causes more impressive wall thickening, mesenteric infiltration, and ascites than arterial occlusion

SELECTED REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

Oliva IB et al: ACR Appropriateness Criteria ® imaging of mesenteric ischemia. Abdom Imaging. 38(4):714-9, 2013 Barmase M et al: Role of multidetector CT angiography in the evaluation of suspected mesenteric ischemia. Eur J Radiol. 80(3):e582-7, 2011 Yikilmaz A et al: Value of multislice computed tomography in the diagnosis of acute mesenteric ischemia. Eur J Radiol. 80(2):297-302, 2011 Furukawa A et al: CT diagnosis of acute mesenteric ischemia from various causes. AJR Am J Roentgenol. 192(2):408-16, 2009 Gore RM et al: Imaging in intestinal ischemic disorders. Radiol Clin North Am. 46(5):845-75, v, 2008 Romano S et al: Small bowel vascular disorders from arterial etiology and impaired venous drainage. Radiol Clin North Am. 46(5):891-908, vi, 2008 Umphrey H et al: Differential diagnosis of small bowel ischemia. Radiol Clin North Am. 46(5):943-52, vi-vii, 2008 Hong SS et al: MDCT of small-bowel disease: value of 3D imaging. AJR Am J Roentgenol. 187(5):1212-21, 2006 Romano S et al: Ischemia and infarction of the small bowel and colon: spectrum of imaging findings. Abdom Imaging. 31(3):277-92, 2006

Ischemic Enteritis Small Intestine

(Left) Axial CECT in a 24-yearold man with pain shows thrombus within the lumen of the superior mesenteric and portal veins. Small bowel is markedly dilated and fluid filled . The wall is thickened and ascites is present, findings worrisome for transmural ischemic injury. (Right) Note the engorged mesenteric veins and mesenteric edema in the same patient, typical of venous-side thrombosis and bowel ischemia. This patient was subsequently diagnosed with a hypercoagulable state and responded to anticoagulation.

(Left) Axial CECT shows mural thickening of the jejunum , which lies on the right side of the abdomen due to congenital malrotation. Note the aberrant position of the superior mesenteric vessels and focal ascites . Ischemic bowel and adhesions were found at surgery. (Right) Axial CECT shows focal ascites and mesenteric infiltration near a segment of small bowel with mural thickening and luminal dilation , diagnostic of closed loop obstruction with ischemia. The proximal SB and colon are of normal caliber.

(Left) Axial CECT shows marked dilation of a long segment of mid small intestine , along with infiltration of the mesentery and ascites near the dilated loops. The small bowel upstream and downstream from this segment is of normal caliber. These are classic findings of a closed-loop obstruction with resulting ischemia. (Right) Lower CT section in the same patient shows the ischemic bowel and ascites .

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Small Intestine

Mesenteric and Small Bowel Trauma KEY FACTS

IMAGING • Duodenum and proximal jejunum are most common sites • Bowel wall thickening > 3 mm (sensitivity of 75%) • Bowel wall enhancement hyperdense to psoas muscle or isodense to blood vessels • Wall enhancement + thickening + free fluid strongly suggests perforation • Sentinel clot sign: Localized > 60 HU mesenteric hematoma at site of bleeding ○ Polygonal fluid collections between folds of mesentery, bowel loops ○ Indicates bowel &/or mesenteric injury • Active bleeding = isodense with enhanced vessels • Extraluminal gas: Intra- or retroperitoneal air ○ May be absent even with transmural lacerations • Seat belt sign: Infiltration or hematoma in subcutaneous fat of lower anterior abdominal wall • Free fluid without an apparent solid organ injury

(Left) Axial CECT in a 24-yearold man injured in a motor vehicle crash (MVC) shows a sentinel clot , adjacent to thick-walled jejunum, and active bleeding, as evidenced by the contrast extravasation . All characteristic findings in intestinal trauma. (Right) Coronal CECT in the same patient shows an injured branch of the superior mesenteric artery with a large focus of contrast extravasation . The mesenteric injury was surgically repaired and a segment of small intestine was resected.

(Left) Axial CECT in a 28-yearold man who was injured in an MVC demonstrates ectopic gas adjacent to a thick-walled jejunal segment , indicative of transmural laceration or perforation. (Right) Axial CECT in the same patient demonstrates mesenteric stranding , a characteristic finding in the setting of intestinal trauma.

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○ Larger amounts, especially of blood attenuation (> 35 HU) are due to trauma ○ Look carefully for mesenteric, bowel, or solid visceral injury

CLINICAL ISSUES • Bowel and mesenteric injuries are found in 2-5% of patients taken to surgery after abdominal trauma • Active mesenteric bleeding requires surgery • Use of seat belt restraints has decreased mortality from motor vehicle crash ○ Incidence of bowel and mesenteric injuries has increased

DIAGNOSTIC CHECKLIST • Solid visceral injuries are often more obvious, but less important than injuries to bowel or mesentery • CT is much more accurate in diagnosis of bowel injury from blunt trauma as opposed to penetrating trauma (e.g., stab wound to the abdomen)

Mesenteric and Small Bowel Trauma

General Features • Best diagnostic clue ○ Bowel wall thickening, mesenteric infiltration, intraperitoneal blood, ± extravasation of enteric or vascular contrast medium • Location ○ Duodenum and proximal jejunum are most common sites

CT Findings • Must view at abdominal and lung windows • Bowel wall thickening > 3 mm (sensitivity of 75%) • Bowel wall enhancement hyperdense to psoas muscle or isodense to blood vessels ○ Wall enhancement + thickening + free fluid strongly suggests perforation • Mesenteric infiltration ("stranding") ○ Small hemorrhages: Streaky soft tissue infiltration of mesenteric fat ○ Sentinel clot sign: Localized > 60 HU mesenteric hematoma at site of bleeding • Intra-/retroperitoneal free fluid: Hemoperitoneum or bowel contents ○ Hemoperitoneum: Present is essentially all bowel or mesenteric injuries ○ Polygonal fluid collections between folds of mesentery, bowel loops – Indicates bowel &/or mesenteric injury – Does not result from injury to solid viscera ○ Hematoma (> 60 HU), liquefied blood (35-50 HU) ○ Bowel content, extravasated enteric contrast (10-30 HU) ○ Active bleeding = isodense with enhanced vessels ○ Bowel rupture at sites of oral contrast extravasation • Extraluminal air: Intra- or retroperitoneal air ○ Not diagnostic of bowel perforation (also seen in barotrauma and mechanical ventilation) – Often seen in subphrenic spaces – Between mesenteric leaves, omental interstices – May be absent even with transmural lacerations • Intramural air and extraluminal air and interloop free fluid ○ Indicates full thickness tear • Bowel discontinuity: Diagnostic of transmural laceration, but rare finding • Extraluminal oral contrast material: Rare, but specific for perforation • Seat belt sign: infiltration or hematoma in subcutaneous fat of lower anterior abdominal wall ○ Highly predictive of injury to bowel and mesentery • Chance fracture: Transverse plane fracture through vertebral body and posterior elements ○ Highly associated with bowel and mesenteric injuries • Free fluid without apparent solid organ injury ○ Normal in young woman (physiological) ○ Small amounts in pelvis of near-water attenuation in men may be due to overhydration ○ Larger amounts, especially of blood attenuation (> 35 HU), are due to trauma – Look carefully for mesenteric, bowel, or solid visceral injury

– Alert clinical team of need for close and repeated monitoring if surgery is to be delayed

Ultrasonographic Findings • Grayscale ultrasound ○ Free fluid in abdomen and pelvis ○ Focused abdominal sonography for trauma (FAST exam) – Never shows bowel injury; only nonspecific free intraperitoneal fluid

Small Intestine

IMAGING

Imaging Recommendations • Best imaging tool ○ Multiplanar CECT • Protocol advice ○ IV contrast bolus at 3 mL/sec ○ Oral contrast use is safe, but uncommonly indicated

DIFFERENTIAL DIAGNOSIS Shock Bowel • Intense mucosal enhancement, submucosal edema (not blood) • With diffuse mesenteric edema, signs of hypovolemia ○ Collapsed IVC, hyperenhancement of kidneys ± adrenals, etc. • Reversible sign of recent hypotension • Resolves quickly with fluid resuscitation

Coagulopathy • May result in intramural hematoma of bowel • Usually due to anticoagulant treatment • Barium studies, CT of SB ○ Segmental, extensive, or localized changes ○ Uniform, regular thickening of valvulae conniventes with symmetric, spike-like configuration, decreased luminal diameter simulating "stack of coins" ○ Intramural hematoma: Intramural mass (~ 60 HU)

Vasculitis • CT findings ○ Segmental bowel wall thickening with mucosal hyperenhancement, submucosal edema ○ Pneumatosis ± portal venous gas – May result from ischemia or medical therapy (e.g., steroids)

PATHOLOGY General Features • Etiology ○ Most common causes – Motor vehicle accidents (MVA) > falls, assault ○ Impact injuries – Crushing of bowel against spine – Location: SB of limited mobility (duodenum, near ligament of Treitz, ileocecal valve) – Transverse tears of mesentery hematoma bowel infarction ○ Mesenteric injury – Hematoma: Most common "alimentary" injury seen on CT 417

Small Intestine

Mesenteric and Small Bowel Trauma

Gross Pathologic & Surgical Features

Treatment

• Contusion, laceration, bowel discontinuity • Wall thickening, blood clot, rupture • "Degloving" injury: Serosa is torn from surface of bowel ○ Often results in delayed ischemic injury to bowel ○ Ischemic stricture or perforation are recognized complications

• Minor injury: IV fluids, monitor vital signs, blood transfusion, antibiotics ○ Mortality of 5-30% with isolated small bowel injury • Major injury: Surgery for perforation or active bleed ○ Injured bowel is usually resected with immediate reanastomosis ○ Anastomosis may be postponed in cases of abdominal contamination

CLINICAL ISSUES Presentation

Associated Injuries

• Most common signs/symptoms ○ Abdominal pain, distension, tenderness, guarding ○ Hypotension, tachycardia ○ Loss of consciousness, shock due to increased blood loss • Lab data ○ Altered CBC, electrolytes, BUN, creatinine, amylase, PT, PTT, and hematocrit • Diagnostic peritoneal lavage (DPL) ○ RBC > 150,000/mm³, WBC > 500/mm³ ○ Food, bile, or bacteria on Gram stain from aspirate ○ "Positive" DPL often resulted in nontherapeutic laparotomy (minor visceral or mesenteric injuries were found commonly – Rarely used in most trauma centers

• Traumatic abdominal wall hernia ○ Most common is avulsion of muscle insertions on iliac crest ○ Highly associated with bowel and mesenteric injury • Injury to solid abdominal viscera ○ Present in most, but not all, cases of traumatic bowel injuries

Demographics • Age ○ Any age group • Gender ○ M=F • Epidemiology ○ Abdominal trauma: Leading cause of death in USA in patients < 40 years of age ○ Children: Intramural hematoma is more common than transection – Children are injured with less kinetic energy ○ Adults: Bowel wall transection is more common than intramural hematoma ○ Bowel and mesenteric injuries are found in 2- 5% of patients taken to surgery after abdominal trauma

Natural History & Prognosis • Complications ○ Perforation sepsis abdominal abscess peritonitis shock death • Prognosis ○ Good if diagnosed and treated early ○ Poor if diagnosis and treatment delayed beyond 24 hours – Increases morbidity and mortality up to 65% • Use of seat belt restraints has decreased mortality from motor vehicle crash ○ Incidence of bowel and mesenteric injuries has increased 418

○ Lap portion of seat belt can act as a fulcrum and cause direct trauma to bowel and mesentery ○ Clinicians and radiologists should look for seat belt contusion of the lower abdominal wall – Seat belt sign is highly predictive of bowel and mesenteric injury

– Complications: Disruption of mesenteric vasculature, hemorrhage, GI tract perforation – Active mesenteric bleeding requires surgery □ Embolization of bleeding vessels may cause bowel ischemia □ Injury to adjacent bowel cannot be excluded

DIAGNOSTIC CHECKLIST Consider • CT is much more accurate in diagnosis of bowel injury from blunt trauma as opposed to penetrating trauma (e.g., stab wound to abdomen) • Bowel and mesenteric injuries are missed by clinicians and radiologists much more often than injuries to solid viscera

Image Interpretation Pearls • CT evidence of extraluminal air/contrast, bowel wall thickening, free fluids, mesenteric "stranding"

SELECTED REFERENCES 1. 2.

3.

4.

5. 6. 7. 8. 9.

Barnett RE et al: Small bowel trauma: current approach to diagnosis and management. Am Surg. 80(12):1183-91, 2014 Honaker D et al: Blunt traumatic abdominal wall hernias: Associated injuries and optimal timing and method of repair. J Trauma Acute Care Surg. 77(5):701-704, 2014 Steenburg SD et al: Multi-detector CT of blunt mesenteric injuries: usefulness of imaging findings for predicting surgically significant bowel injuries. Abdom Imaging. ePub, 2014 Ekeh AP et al: Diagnosis of blunt intestinal and mesenteric injury in the era of multidetector CT technology--are results better? J Trauma. 65(2):354-9, 2008 Linsenmaier U et al: Diagnosis and classification of pancreatic and duodenal injuries in emergency radiology. Radiographics. 28(6):1591-602, 2008 Hanks PW et al: Blunt injury to mesentery and small bowel: CT evaluation. Radiol Clin North Am. 41(6):1171-82, 2003 Hawkins AE et al: Evaluation of bowel and mesenteric injury: role of multidetector CT. Abdom Imaging. 28(4):505-14, 2003 Butela ST et al: Performance of CT in detection of bowel injury. AJR Am J Roentgenol. 176(1):129-35, 2001 Brody JM et al: CT of blunt trauma bowel and mesenteric injury: typical findings and pitfalls in diagnosis. Radiographics. 20(6):1525-36; discussion 1536-7, 2000

Mesenteric and Small Bowel Trauma Small Intestine

(Left) Axial CECT in a 19-yearold man presenting with abdominal pain after an MVC shows free air , hyperdense thickened bowel wall , and infiltrated mesentery consistent with a hematoma . Jejunal perforation was revealed at surgery. (Right) Axial CECT in a 71-year-old woman with severe abdominal pain after an MVC shows extraluminal gas adjacent to the thickened and collapsed cecum . Note adjacent bowel wall thickening of the terminal ileum. Cecal and distal ileal perforations were confirmed at surgery.

(Left) Axial CECT in a 58-yearold man with abdominal pain after an MVC shows active arterial extravasation and a sentinel clot from a mesenteric laceration. A torn mesenteric artery was revealed at surgery, but no bowel injury. (Right) Axial CECT in a 22-year-old man injured in a bicycle accident shows a mesenteric hematoma (34 HU) within an interloop compartment. Note the angular margins of the mesenteric collection. There were no signs of bowel injury and the patient recovered without surgery.

(Left) Axial CECT in a 62-yearold woman presenting with abdominal pain after an MVC demonstrates an abdominal wall hematoma from a seat belt injury . Seat belt contusions are highly associated with bowel and mesenteric injuries. (Right) Axial CECT in the same patient illustrates active arterial bleeding within a mesenteric hematoma. The adjacent bowel was also found to be injured at surgery. Active mesenteric bleeding from trauma generally demands surgical intervention.

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Small Intestine

Mesenteric and Small Bowel Trauma

(Left) This 44-year-old man was injured in an MVC. CT shows blood (45-50 HU) in the upper abdomen without an apparent hepatic or splenic injury. (Right) Another CT section in the same patient shows higher density (65 HU) blood (sentinel clot) as angular (polygonal) mesenteric and left paracolic collections. Mesenteric laceration without bowel injury was confirmed at surgery.

(Left) This 30-year-old woman was injured in an MVC. CT shows a thick-walled jejunum and active bleeding into the mesentery, with fluid isodense to enhanced blood vessels. (Right) CT in the same patient, shown at lung windows, shows free intraperitoneal gas (air) , diagnostic of transmural laceration. The active mesenteric bleeding alone would have warranted surgical intervention in this case.

(Left) This 54-year-old woman was injured in an MVC. CT shows active hemorrhage , hyperenhancing, thickened SB wall , and interloop hematoma . Also seen is an abdominal wall hematoma from the seat belt impact and diffuse mesenteric infiltration . (Right) CT in the same patient shows a traumatic abdominal wall hernia containing segments of colon and small bowel. Extraluminal gas is noted . At surgery, serosal avulsion and transmural laceration of the small bowel were confirmed.

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Mesenteric and Small Bowel Trauma Small Intestine

(Left) This young man was injured in an MVC. CT with lung windows shows free intraperitoneal air . (Right) The same CT section at soft tissue windows shows free peritoneal fluid measuring about 20 HU, likely representing a mixture of blood and extraluminal bowel contents.

(Left) CT in the same patient shows higher density (60HU) sentinel clots adjacent to jejunum and cecum, and more free air . (Right) Another CT section in the same patient shows intermediate density fluid (35HU) in the pelvis . No solid visceral injuries were evident.

(Left) An additional CT section in the same patient shows infiltration and hematomas in the subcutaneous fat of the abdominal wall at the level of the iliac crests. This is a classic seat belt sign. (Right) A sagittal reformatted CT section in the same patient shows a horizontal fracture through the L3 vertebral body and posterior elements, a classic Chance fracture. This and the seat belt contusion are highly associated with bowel and mesenteric injuries. Jejunal and cecal lacerations were confirmed at surgery.

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Small Intestine

Postoperative State, Bowel KEY FACTS

IMAGING • Afferent loop (AL) syndrome ○ AL becomes obstructed by adhesions, recurrent tumor, internal hernia, etc. ○ CT is much better than fluoroscopic studies for this diagnosis • Colonoscopy and other endoscopic procedures ○ Prevalence of complications is 1-2% ○ CT shows perforation best and more safely • Enterectomy and anastomosis ○ Low rectal anastomoses are especially prone to ischemia, stricture, leak,and fistulas • Small bowel (SB) anastomoses ○ Side-to-side anastomosis may simulate obstruction or "aneurysmal dilation" ○ Identify metallic staple lines for this iatrogenic finding • Ileoanal pouch

(Left) Lateral view of the pelvis shows the results of a prior proctocolectomy, with creation of a J-shaped ileal pouch that has been anastomosed to the anal sphincter . (Right) "Pouchogram" shows evidence of the prior colectomy with an ileoanal pouch . The balloon tip of the catheter used to inject the contrast medium is just above the ileoanal anastomosis. The sharp angulation and tethered appearance of a segment of small bowel are typical of an adhesive small bowel obstruction.

(Left) Axial CECT in a patient with afferent loop syndrome following Billroth II procedure shows dilated bile ducts down to the ampulla. The afferent limb (duodenum) is dilated due to a stricture that caused partial bowel obstruction. (Right) Dilated duodenum (same patient) is filled with oral contrast medium, which is somewhat unusual since a stricture at the gastroenteric anastomosis often precludes filling of this segment. The elevated intraluminal pressure within the duodenum contributed to the biliary obstruction.

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•

• • •

○ Create reservoir (pouch) of ileum that is anastomosed to distal rectum or anal sphincter ○ Fluoroscopic and CT studies are complementary and essential to diagnose complications ○ Usually perform "pouchogram" (fluoroscopic controlled contrast injection of ileoanal pouch through anus) ○ Performed whenever leak or stricture is suspected ○ Performed prior to takedown of diverting ileostomy For fluoroscopic retrograde contrast injection ○ Use soft catheter with balloon inflated within healthy portion of bowel Enteroclysis: May show subtle adhesive obstruction or leak missed by other modalities CT enterography (ingested contrast medium) or enteroclysis (pump-injected contrast medium) CT has advantage of better delineation of disease beyond bowel wall (e.g., abscess)

Postoperative State, Bowel

Definitions • Enterotomy: Surgical entry of bowel to remove polyp, foreign body, etc., or to insert enteric tube • Enteroplasty: Surgical alteration of bowel, usually to open a strictured segment • Plication: Alteration of bowel to relieve obstruction • Enterectomy: Resection of damaged or neoplastic segment of bowel • Colectomy: Resection of damaged or neoplastic segment of colon • Ostomy: Temporary or permanent opening of bowel onto surface of abdomen for feeding or drainage purposes

IMAGING General Features • Gastrointestinal surgery ○ Involves resection of some portion of stomach and proximal bowel with creation of gastroenteric anastomosis – e.g., Billroth II partial gastrectomy, Whipple procedure (pancreaticoduodenectomy) ○ Dumping syndrome – Loss of pyloric sphincter allows rapid emptying of hyperosmotic gastric contents into jejunum – Symptoms: Nausea, urgent diarrhea, lightheadedness immediately after eating – Imaging: Nonspecific; may show dilation and hyperperistalsis of jejunum ○ Afferent loop (AL) syndrome – AL becomes obstructed by adhesions, recurrent tumor, internal hernia, etc. – AL varies by type of surgical procedure □ Billroth II: AL = duodenum □ Whipple: AL = Roux jejunal loop □ Roux-en-Y gastric bypass: AL = duodenum and proximal jejunum ("pancreaticobiliary limb") – Symptoms: Nonspecific; no bilious vomiting; dilation of AL may result in progressive dilation of AL and perforation; may lead to malnutrition, jaundice – Imaging: Plain films and barium fluoroscopic exams often miss this complication as AL is fluid-distended and oral contrast medium does not enter AL – CT shows dilation of AL and any complications (e.g., dilated bile ducts, recurrent tumor, perforation) • Colonoscopy and other endoscopic procedures ○ Complication rate is low but varies by clinical setting, type of procedure, and experience of endoscopist ○ Perforation – Can occur ± biopsy – Prevalence is < 1% for "routine" colonoscopy – Prevalence after polypectomy about 1-2% – CT detects extraluminal gas and fluid more accurately than plain radiography ○ Bleeding – Occurs in 30-50% who have polypectomy □ Usually resolves without specific treatment ○ Postpolypectomy syndrome

– Due to burn of colonic wall during polyp removal by "hot wire" snare – Symptoms: Pain, fever, leukocytosis – Usually resolves with medical and supportive therapy • Enterectomy and anastomosis ○ Any resection and anastomosis done in setting of peritoneal contamination or borderline viability of bowel is prone to dehiscence or stricture – Low rectal anastomoses are especially prone to ischemia, stricture, leak, fistulas □ Vascular supply is tenuous and surgical exposure of operative field is limited ○ Small bowel (SB) anastomoses – May be end-to-end, end-to-side, side-to-side – End-to-end is most physiologic but most prone to anastomotic stricture – End- or side-to-side anastomoses have lower prevalence of stricture or obstruction but higher rate of stasis within "blind segments" □ May cause bacterial overgrowth problems – Side-to-side: Bowel appears at least twice diameter of normal bowel □ May simulate "aneurysmal dilation" but no thickening of wall (unlike SB lymphoma, metastases, or GIST, other causes of aneurysmal dilation) – Imaging □ CT usually shows metallic staples at anastomotic suture line □ Water-soluble contrast medium can be administered orally, rectally, or through ostomy to visualize anastomosis and other bowel segments ○ Short bowel syndrome – Follows resection of critical length of SB □ Jejunal length < 200 cm usually necessitates nutritional support □ Loss of ileum leads to deficiency of vitamin and bile salt absorption □ Usual reasons for loss of SB: Recurrent surgery for Crohn disease, intestinal ischemia, strangulated internal hernia, Gardner syndrome with mesenteric desmoids □ Can be treated with long-term parenteral nutrition or small bowel transplantation □ Fluoroscopic small bowel study & CT are used to estimate length and health of remaining bowel • Enterostomy ○ Often for placement of jejunal feeding tube for longterm enteral nutrition ○ Pneumatosis in this setting does not necessarily indicate bowel infarction or ischemia ○ Complications: Leak of enteric contents; obstruction ○ Caution: Use of balloon-tipped catheter within SB is associated with risk of intussusception and obstruction • Ileostomy ○ Conventional (end) ileostomy – Distal ileum brought (permanently) to skin surface – Leads to fecal incontinence, requires ileostomy bag ○ "Loop" (double-barrel, diverting) ileostomy – Usually intended as temporary diversion of most or all of fecal stream

Small Intestine

TERMINOLOGY

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Small Intestine

Postoperative State, Bowel

– Usually performed in setting of recent distal bowel anastomosis – Diverting ostomy decompresses bowel to protect distal anastomosis until healing is complete ○ Complications – Adhesions, recurrent disease, parastomal herniation (of fat ± bowel) • Small bowel reservoirs ○ Continence-preserving surgical procedures ○ Preferred technique to restore function and body image following colectomy ○ Koch-type continent ileostomy (uncommonly performed) – Complex surgical procedure that results in internal ileal reservoir & continence (no bag) but requires periodic emptying of reservoir by intubation of stoma ○ Ileoanal pouch – Now the preferred procedure following colectomy – 2 important components □ Remove mucosa of rectum/anus (to prevent recurrence of original disease) □ Create reservoir (pouch) of ileum that is anastomosed to distal rectum or anal sphincter – Simplest to illustrate and perform is "J" pouch □ Pouch created by taking distal 25 cm of ileum and forming into "J" shape with side-to-side anastomosis of adjacent segments □ Dependent part of pouch is anastomosed to rectum or anus – Diverting ileostomy is usually performed to protect anastomotic staple lines □ Contrast enema (through rectum or ileostomy) or CECT is performed to establish patency and integrity of anastomosis □ Following confirmation of intact pouch and anastomosis, diverting ostomy is closed (about 8-12 weeks after surgery) – Complications □ Anastomotic strictures or dehiscence, abscess, adhesions, fistulas, "pouchitis" □ Ileoanal pouch "failure" (need for permanent end ileostomy) in about 10% – Caution □ Surgeon may leave blind-ending pouch that communicates with main pouch □ Enteric contrast ± gas may fill this and mimic leak of extraluminal contents – Imaging evaluation □ Usually perform "pouchogram" (fluoroscopiccontrolled contrast injection of ileoanal pouch through anus) □ Performed whenever leak or stricture is suspected □ Performed prior to takedown of diverting ileostomy

Imaging Recommendations • Protocol advice ○ For fluoroscopic inspection of bowel using retrograde contrast injection – Use soft balloon-tipped catheter with balloon inflated within healthy portion of bowel 424

– Then snug balloon up against inner side of ostomy or anastomosis – Do not inflate balloon within anastomosis or ostomy itself ○ Fluoroscopic enteroclysis – Best technique for detailed depiction of bowel anatomy □ May show subtle adhesive obstruction or leak missed by other modalities ○ CT enterography (ingested contrast medium) or enteroclysis (pump-injected contrast medium) – Probably equivalent to fluoroscopic enteroclysis for evaluation of bowel – CT has advantage of better delineation of disease beyond bowel wall □ Abscess, fistula, etc. ○ Multiplanar reformations of CT are essential – Coronal and other planes frequently help delineate pertinent anatomy and pathology

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Always review operative report prior to performing examination ○ Postoperative anatomy may be complicated and confusing, especially in patients with multiple prior bowel resections

SELECTED REFERENCES 1. 2.

3.

4. 5. 6.

7. 8. 9. 10. 11. 12.

13. 14. 15.

Farinella E et al: Modified H-pouch as an alternative to the J-pouch for anorectal reconstruction. Colorectal Dis. 16(9):O332-4, 2014 Sanada Y et al: Recurrent cholangitis by biliary stasis due to non-obstructive afferent loop syndrome after pylorus-preserving pancreatoduodenectomy: report of a case. Int Surg. 99(4):426-31, 2014 Lee WY et al: Endoscopic treatment of efferent loop syndrome with insertion of double pigtail stent. World J Gastroenterol. 19(41):7209-12, 2013 Hoda KM et al: Predictors of pouchitis after ileal pouch-anal anastomosis: a retrospective review. Dis Colon Rectum. 51(5):554-60, 2008 Kiran RP et al: Complications and functional results after ileoanal pouch formation in obese patients. J Gastrointest Surg. 12(4):668-74, 2008 Pfefferkorn U et al: Recurrent pancreatitis as only presenting symptom of intermittent small bowel obstruction after biliopancreatic diversion with duodenal switch. Surg Obes Relat Dis. 4(2):202-4, 2008 Power N et al: CT assessment of anastomotic bowel leak. Clin Radiol. 62(1):37-42, 2007 Crema MD et al: Pouchography, CT, and MRI features of ileal J pouch-anal anastomosis. AJR Am J Roentgenol. 187(6):W594-603, 2006 Sandrasegaran K et al: CT findings for postsurgical blind pouch of small bowel. AJR Am J Roentgenol. 186(1):110-3, 2006 Sandrasegaran K et al: CT of acute biliopancreatic limb obstruction. AJR Am J Roentgenol. 186(1):104-9, 2006 Sandrasegaran K et al: Small-bowel complications of major gastrointestinal tract surgery. AJR Am J Roentgenol. 185(3):671-81, 2005 Hui GC et al: Small-bowel intussusception around a gastrojejunostomy tube resulting in ischemic necrosis of the intestine. Pediatr Radiol. 34(11):916-8, 2004 Blake MF et al: Intestinal obstruction following biliopancreatic diversion. Dig Dis Sci. 48(4):737-40, 2003 Kim HC et al: Afferent loop obstruction after gastric cancer surgery: helical CT findings. Abdom Imaging. 28(5):624-30, 2003 Carucci LR et al: Evaluation of patients with jejunostomy tubes: imaging findings. Radiology. 223(1):241-7, 2002

Postoperative State, Bowel Small Intestine

(Left) Axial NECT shows portal venous gas in this patient with recurrent bowel obstruction following prior enterectomy. (Right) Axial CECT in the same patient shows marked dilation of a segment of SB , but the presence of surgical staples and absence of a bowel wall mass indicate that this is the result of a prior side-to-side anastomosis. The proximal SB is dilated, while the distal bowel is collapsed . The obstruction & portal venous gas resolved without surgery and were presumed to have resulted from adhesive SBO.

(Left) Axial CECT in a patient with abdominal pain following colonoscopy and biopsy of a cecal mass shows extraluminal gas near the cecum that is both retroperitoneal and intraperitoneal . The biopsy had shown adenocarcinoma of the cecum, and this and the perforation were confirmed at surgery. (Right) Axial CECT in a patient with pain & fever following proctocolectomy for diverticulitis shows metallic staples at the site of the sigmoid anastomosis and extraluminal gas, fluid, and enteric contrast media .

(Left) Axial CECT in the same patient shows more of the extraluminal gas and contrast medium , including some that has entered the vagina , indicating colovaginal fistula from an anastomotic breakdown. (Right) Spot film from a contrast enema in the same patient shows narrowing at the level of the anastomosis , retrorectal extravasation , and filling of the vagina . Anastomotic leaks often result in infection and further breakdown of the anastomosis; abscesses and fistulas commonly result.

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Small Intestine

Radiation Enteritis and Colitis KEY FACTS

• Damage of small bowel or colonic mucosa and wall due to therapeutic or excessive irradiation

IMAGING • Best imaging tools ○ Multiplanar CECT, enteroclysis, barium enema • Single or multiple stenoses (strictures) of varying length (up to several cm) • Acute: CT submucosal edema (near water density) ○ Fluoroscopy: Bowel loops appear spastic ( lumen diameter) with thickened folds (edema) • Subacute or chronic ○ Peristaltic activity is decreased or absent ○ Stenoses bowel obstruction with dilation of proximal bowel loops ○ Adhesions angulation between adjacent loops, fixation of loops

(Left) This 63-year-old man is 4 weeks status post radiation therapy for rectal cancer, now with pelvic pain and diarrhea. CT shows submucosal edema within a rigid-appearing loop of distal ileum, compatible with acute radiation enteritis. (Right) Axial CECT in the same patient reveals numerous fluid-filled loops of proximal bowel, suggesting functional obstruction due to the radiation. The patient was treated with steroids and symptoms resolved over a 2week period.

(Left) This 63-year-old man with a history of radiation therapy for sacral metastases, now presents with constipation. Spot film from a barium enema reveals a persistent and high-grade stricture of the rectum , typical for radiation proctitis. (Right) Axial CECT in the same patient confirms the narrowed lumen and thickened wall of the rectosigmoid colon . Also evident is the lytic process in the sacrum , representing the metastatic focus that was the target of the radiation therapy.

426

○ ± sinuses or fistulas (from bowel to skin, vagina, bladder, other bowel)

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • •

Crohn disease Metastases and lymphoma Ischemic enteritis Primary bowel tumor

CLINICAL ISSUES • Usually follows radiotherapy for primary pelvic tumors ○ Acute radiation enteritis or colitis often resolves spontaneously within weeks ○ Moderate to severe chronic radiation enteritis/colitis develops in 5-15% • Diagnosis is usually suggested by clinical and imaging features ○ Confirmed by endoscopy and biopsy if necessary

Radiation Enteritis and Colitis

Definitions • Damage of small bowel or colonic mucosa and wall due to therapeutic or excessive irradiation • Chronic radiation enteritis/colitis: Late intestinal toxicity after radiotherapy

IMAGING

MR Findings • T2WI ○ Thick, high signal intensity bowel wall layer suggests submucosal edema, not tumor invasion ○ "Target" pattern: Thickened high signal intensity submucosa surrounded by low signal intensity muscularis propria and muscularis mucosae ○ ± bowel fistula: Fluid in tract appears as high signal, contrasted by soft tissue and fat

General Features

Imaging Recommendations

• Best diagnostic clue ○ Mural thickening, luminal narrowing of pelvic bowel loops • Location ○ Small bowel (ileum more common than jejunum) ○ Abdominal or pelvic colon (radiation colitis) and rectum (radiation proctitis)

• Best imaging tool ○ Fluoroscopic-guided enteroclysis, fluoroscopic-guided barium enema, multiplanar CECT

Radiographic Findings • Fluoroscopic-guided enteroclysis ○ Acute – Bowel loops appear spastic ( lumen diameter) with thickened folds (edema) ○ Subacute or chronic – Thickened valvulae conniventes and intestinal wall (edema, fibrosis) □ Thickened folds appear straight and parallel □ "Stack of coins" appearance: Enlarged smooth, straight, parallel folds perpendicular to longitudinal SB axis – Effacement of valvulae conniventes (late, atrophic feature) – Single or multiple stenoses (strictures) of varying length (up to several cm) – Stenoses bowel obstruction with dilation of proximal bowel loops – Adhesions angulation between adjacent loops, fixation of loops – Peristaltic activity is decreased or absent – Sinuses and fistulas (especially at damaged, surgical anastomotic site caused by radiation) • Fluoroscopic-guided barium enema ○ Chronic – Diffuse or focal narrowing, tapered margins – Rectal stricture or rectovaginal fistula can be seen – Widened presacral space on lateral view

CT Findings • Bowel wall thickening ○ Acute: Submucosal edema (near water density) ○ Chronic: Closer to soft tissue density • Luminal narrowing, strictures ○ Usually focal or segmental ○ Dilation of bowel lumen upstream from strictures, ± airfluid levels • Mesenteric or perirectal infiltration (acute) or fibrosis (chronic) • ± sinuses or fistulas ○ From small bowel, colon, or rectum, to other bowel segments, urinary bladder, or vagina

Small Intestine

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Crohn Disease • Usually affects distal small bowel with skip areas • Distribution of disease and clinical history usually allow distinction

Metastases and Lymphoma • Often cause wall thickening and luminal narrowing ○ Radiation injury and tumor of bowel may coexist ○ Tumors usually are more focal than radiation enteritis/colitis ○ Tumors usually cause more soft tissue density wall thickening or mass effect ○ CT often shows associated lymphadenopathy, solid neoplasms

Ischemic Enteritis • Acute or subacute ischemia and radiation can both cause submucosal hemorrhage "stack of coins" appearance • Chronic ischemic enteritis or colitis may be indistinguishable from chronic radiation injury ○ Distribution of disease, clinical history may allow distinction

Primary Bowel Tumor • Usually more mass effect than with radiation enteritis • Can cause irregular stricture, usually over shorter length than with radiation injury

PATHOLOGY General Features • Etiology ○ Radiation therapy for cancer of cervix, uterus, ovary, cecum, colon, rectum, or bladder – Also for osseous metastases, stomach, or pancreatic cancer ○ Risk factors of chronic radiation enteritis – Bowel segments are fixed in position □ Rectosigmoid colon □ Adhesions may fix small bowel in position (from prior surgery, radiation, or peritonitis) – High radiation dose over short period of time – Hypertension, atherosclerosis, diabetes mellitus, connective tissue disease, HIV □ Result in vasculopathy that impairs the bowels' ability to withstand or repair radiation injury 427

Small Intestine

Radiation Enteritis and Colitis

– Chemotherapy with radiation augments radiation damage to bowel ○ Pathogenesis (2 methods) – Direct cytotoxic effect: Radiation free radicals interact with DNA elimination of replication, transcription, and protein synthesis cell disruption and death – Ischemic changes: Medial wall thickening and subendothelial proliferation endarteritis obliterans fibrosis • Radiation tolerance ○ Duodenum, jejunum, ileum, transverse colon, sigmoid colon, esophagus, and rectum (from highest to lowest tolerance)

Natural History & Prognosis • Acute radiation enteritis or colitis often resolves spontaneously within weeks • Complications ○ Fistula, stricture, SBO, hemorrhage, abscess, perforation • Prognosis ○ Good with medical treatment and reduction/cessation of radiation ○ Poor with chronic radiation injuries with complications

Staging, Grading, & Classification

Treatment

• Classification ○ Acute: Concurrent with or < 2 months after treatment – Mucosa: Thinning (reduction of crypt cell mitoses) and edema □ Hyperemia and ulceration – Submucosa: Edema ○ Subacute: 2-12 months after treatment – Mucosa: In process of healing – Submucosa: Obliterative changes in arterioles, fibrotic thickening ○ Chronic: 12 months to 30 years after treatment – Muscularis propria: Fibrosis – Serosa: Diffuse hyaline change adhesions between bowel segments – Ulceration and fibrosis strictures

• Reduction/cessation of radiation; medical treatment, lowresidue diet • Surgery for strictures or fistulas if medical treatment fails

Microscopic Features • Obliterative endarteritis • Chronic phase includes exaggerated fibrosis within wall and serosa ○ Predisposes to luminal obstruction, adhesions, fistulas, perforation

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute – Abdominal cramping, nausea, vomiting, tenesmus, watery diarrhea – Dehydration, malabsorption (change in SB flora) – Radiation proctitis: Mucoid rectal discharge, pain and bleeding – Severity of symptoms proportional to dose and duration of irradiation ○ Chronic – Colicky abdominal pain, nausea, vomiting, tenesmus, bloody diarrhea, steatorrhea, weight loss • Diagnosis is usually suggested by clinical and imaging features ○ Confirmed by endoscopy and biopsy if necessary

Demographics • Epidemiology ○ Most commonly from radiotherapy for primary pelvic malignancies 428

– 80-90% of these will have permanent alteration of bowel habits – Moderate to severe chronic radiation enteritis/colitis develops in 5-15%

DIAGNOSTIC CHECKLIST Consider • Rule out recurrent tumors • History and timing of radiation therapy

Image Interpretation Pearls • SBO, wall thickening with fixed and angulated bowel loops, reduced peristalsis

SELECTED REFERENCES 1. 2. 3. 4. 5.

6. 7.

8. 9. 10. 11.

12. 13. 14. 15.

Harb AH et al: Radiation enteritis. Curr Gastroenterol Rep. 16(5):383, 2014 Qin Q et al: Clinical risk factors for late intestinal toxicity after radiotherapy: a systematic review protocol. Syst Rev. 2:39, 2013 Shadad AK et al: Gastrointestinal radiation injury: symptoms, risk factors and mechanisms. World J Gastroenterol. 19(2):185-98, 2013 Rodríguez ML et al: Gastrointestinal toxicity associated to radiation therapy. Clin Transl Oncol. 12(8):554-61, 2010 Birgisson H et al: Late gastrointestinal disorders after rectal cancer surgery with and without preoperative radiation therapy. Br J Surg. 95(2):206-13, 2008 Kountouras J et al: Recent advances in the management of radiation colitis. World J Gastroenterol. 14(48):7289-301, 2008 Lesperance RN et al: Colorectal complications of external beam radiation versus brachytherapy for prostate cancer. Am J Surg. 195(5):616-20; discussion 620, 2008 Baxter NN et al: Postoperative irradiation for rectal cancer increases the risk of small bowel obstruction after surgery. Ann Surg. 245(4):553-9, 2007 Beasley M et al: Complications of radiotherapy: improving the therapeutic index. Cancer Imaging. 5(1):78-84, 2005 Chen S et al: Small bowel CT fat density target sign in chronic radiation enteritis. Australas Radiol. 47(4):450-2, 2003 Low RN et al: Distinguishing benign from malignant bowel obstruction in patients with malignancy: findings at MR imaging. Radiology. 228(1):157-65, 2003 Bismar MM et al: Radiation enteritis. Curr Gastroenterol Rep. 4(5):361-5, 2002 Horton KM et al: CT of nonneoplastic diseases of the small bowel: spectrum of disease. J Comput Assist Tomogr. 23(3):417-28, 1999 Capps GW et al: Imaging features of radiation-induced changes in the abdomen. Radiographics. 17(6):1455-73, 1997 Bluemke DA et al: Complications of radiation therapy: CT evaluation. Radiographics. 11(4):581-600, 1991

Radiation Enteritis and Colitis Small Intestine

(Left) This 66-year-old woman had ovarian cancer status post debulking procedure and radiation therapy, now presenting with stool per vagina. CT shows rectal wall thickening and mucosal hyperenhancement . There is similar thickening of the bladder wall and hyperenhancement of the bladder mucosa, consistent with radiation cystitis . (Right) CT in the same patient shows obliteration of the fat plane between the vagina and the rectum, and fluid within the vagina, due to colovaginal fistula.

(Left) This 54 year-old woman had surgery and radiation therapy 2 months prior for endometrial carcinoma. CT shows ascites , submucosal edema, and luminal narrowing of multiple small bowel segments in the pelvis. (Right) The bowel segments upstream from the pelvic segments are dilated with air-fluid levels , indicating bowel obstruction. The clinical and imaging features are typical of subacute radiation enteritis.

(Left) This 54-year-old man had pancreatic cancer metastatic to the stomach with subsequent radiation therapy. CT shows mucosal hyperenhancement and submucosal edema of the distal transverse colon, adjacent to the gastric metastasis (not shown). (Right) Coronal CECT in the same patient shows the segmental radiation colitis , as well as the metastasis in the stomach. Ischemic or infectious colitis could have a similar appearance, but colonoscopic biopsy confirmed radiation colitis.

429

Small Intestine

Small Intestine Transplantation KEY FACTS

TERMINOLOGY • Isolated SB transplant (Tx) is primarily for "short gut syndrome" • Multivisceral transplantation (liver, ± pancreas, ± part of stomach) ○ Usually for liver failure due to chronic TPN

• •

IMAGING • Vascular complications: Thrombosis, stricture, pseudoaneurysm (arteries or veins) ○ Less common than for other transplant procedures • Mesenteritis: Present to some degree in all SB transplantation recipients • Opportunistic infections: May affect any organ including allograft • Pneumatosis: Usually not due to ischemia • Ascites: Usually loculated, nonspecific finding ○ Chylous ascites: Presence of fat-fluid levels • Posttransplantation lymphoproliferative disorder (PTLD)

•

•

○ More common in SB (up to 30%) and multivisceral Tx than most other solid organ transplant recipients ○ More common within SB allografts than in host organs Rejection and graft-vs.-host disease ○ Both common, cannot be distinguished on imaging Dilation of SB lumen ○ May result from dysmotility, adhesion, ischemia, or rejection Imaging protocols: Multiplanar CT, ± CT angiography, displays most important anatomical and pathophysiological information pertinent to small bowel Tx Upper GI series to evaluate motility and status of proximal bowel anastomosis

CLINICAL ISSUES • SB Tx: 1-year patient survival (90%); graft survival (~ 75%) ○ Multivisceral Tx: 1-year patient survival (80%) ○ 5-year patient survival: 60% • Worse than for solid organ transplant recipients

Graphic demonstrates some of the altered anatomy in a small bowel transplantation (SB Tx) procedure. The small bowel allograft is usually anastomosed proximally to the distal duodenum or proximal jejunum of the recipient, and distally to the sigmoid , with a temporary "chimney" ileostomy in the right lower quadrant. This ostomy allows convenient access to the allograft in the perioperative period for endoscopic visualization and biopsy procedures, and may be permanent. The donor superior mesenteric vein (SMV) is anastomosed to the host SMV or portal vein . The donor SMA is anastomosed to the host aorta .

430

Small Intestine Transplantation

Abbreviations • Small bowel transplantation (SB Tx)

Indications for Small Bowel Transplantation • Primarily for "short gut syndrome," but also other causes of intestinal failure ○ Small bowel length or function insufficient to provide adequate nutrition – Result of various etiologies □ Superior mesenteric arterial (SMA) or venous (SMV) thrombosis with bowel ischemia, Crohn disease, midgut volvulus, familial polyposis/Gardner (especially with mesenteric desmoids) – Much less commonly due to intestinal pseudoobstruction or other functional deficiency of small bowel ○ Patients can be maintained on total parenteral nutrition (TPN) indefinitely, except for complications – Lack of central venous access to administer TPN, TPN catheter-related sepsis, and TPN-induced cholestatic liver disease • Indications for multivisceral transplantation (liver, ± pancreas, ± part of stomach) ○ Advanced liver disease due to TPN or unrelated cause (e.g., chronic hepatitis) ○ Advanced pancreatic disease ○ Extensive mesenteric thrombosis (with multivisceral ischemia) ○ Severe mesenteric neuropathy • Special considerations for small bowel transplantation ○ Donor intestine contains large number of immunocompetent lymphocytes in bowel wall (e.g., Peyer patches) and mesenteric nodes – prevalence of graft-vs.-host and graft rejection ○ Donor intestine contains large number of bacteria and other potential pathogens – prevalence of postoperative infections ○ Early diagnosis by imaging of graft-related complications helps to morbidity and mortality

IMAGING General Features • Anatomy of SB and multivisceral transplantation ○ Stomach (if included, usually in multivisceral transplants) – Donor greater curvature is preserved with gastroepiploic arteries, and donor stomach is anastomosed to proximal recipient stomach – Usually includes donor duodenum and pancreas ○ Intestine – Most common proximal anastomosis (if not multivisceral Tx): Side-to-side donor jejunum to host duodenum or proximal jejunum – Leftward displacement of gastric antrum and duodenum can result from surgical mobilization – Most common distal anastomosis: Donor ileum to host sigmoid colon □ "Chimney" ileostomy at end of donor ileum (temporary or permanent)

– Percutaneous gastrostomy and jejunostomy tubes are placed initially ○ Liver (if included, as part of multivisceral Tx) ○ Pancreas (if included) – With intact duodenum and SB and liver as part of multivisceral Tx (usually) ○ Vasculature – Arterial □ Isolated small bowel Tx: Donor SMA anastomosed to host aorta □ Multivisceral Tx: 10 cm portion of donor aorta is taken, with celiac trunk and SMA intact, then grafted end-to-side to host aorta – Venous □ Isolated small bowel Tx: Donor SMV is anastomosed to host SMV or portal vein □ Multivisceral Tx: Donor and recipient IVCs may be anastomosed end-to-end □ Portal venous system from donor remains intact; transplanted en bloc

Small Intestine

TERMINOLOGY

Radiographic Findings • Upper GI series with oral contrast ○ Examine allograft, anastomoses, tone, and motility ○ Pathology: Adhesions, volvulus, stenosis, leak – Usually straightforward diagnosis – Introduce water-soluble contrast material via stomach (drinking or PEG tube) □ Via RLQ ileostomy site □ Via jejunostomy tube (present in all patients soon after small bowel Tx) □ Via rectum ○ Measure transit time with radiopaque markers or oral barium contrast – Range: 0.2-17.8 hours – Most patients display delayed gastric emptying associated with decreased gastric peristalsis □ 76% of patients have delayed gastric emptying in 1st 2 months, but only 16% at 6 months □ May be from use of narcotics during perioperative period • Complications ○ Usually detected on CT; less often on MR – Catheter angiography usually performed only after CT, MR, or US has shown evidence of vascular complication ○ Vascular complications – Thrombosis □ Lumen of affected artery or vein fails to opacify with vascular contrast medium – Anastomotic strictures □ Relatively less common in small bowel Tx due to larger vessels involved – Pseudoaneurysm □ Ballooning out of lumen of vessels, usually artery and usually at site of anastomosis □ May be due to surgical error or infection □ Requires surgical revision or intervention (e.g., stent graft) ○ Mesenteritis 431

Small Intestine

Small Intestine Transplantation

○

○

○

○

○

○

○

432

– Almost all SB Tx recipients develop some degree of infiltration and thickening of allograft mesentery □ Usually persists for up to 1 month – Usually associated with bowel wall thickening – May be asymptomatic and of no concern in perioperative period – Probably represents combination of lymphedema (transected lymphatics) and mild rejection – Severe mesenteric ± bowel wall thickening usually due to rejection Rejection and graft-vs.-host disease – Both are common, cannot be distinguished on imaging – Nonspecific findings of allograft wall thickening – Diagnosis: Mucosal biopsy of stomach, duodenum, or small bowel □ Small bowel biopsy usually via ileostomy Opportunistic infections – May affect any organ (e.g., pneumonia) – May affect allograft itself (e.g., CMV enteritis) – Cannot be diagnosed on imaging or differentiated from other causes of SB wall edema Dilation of small bowel lumen – In 2/3 of patients in 1st month post SB Tx – Nonspecific ileus (denervation of small bowel, general response to major surgery) – May result from dysmotility, adhesion, ischemia, or rejection – Endoscopy through ileostomy helps evaluation Pneumatosis – May represent ischemia – Most cases are "benign," due to medications, ± influence of bowel dilation, endoscopy, etc. – Endoscopy used to differentiate Ascites – Present in most patients, at least temporarily □ Usually regresses without treatment – Usually somewhat loculated between bowel loops – Difficult to distinguish from infected ascites □ May require image-guided aspiration of fluid for diagnosis and treatment – Chylous ascites □ Suggested by presence of fat-fluid levels □ Due to interrupted bowel lymphatics Abscess – Increased incidence in small bowel and multivisceral Tx compared to solid organ transplantation – May appear as loculated ascites with thick, enhancing wall, ± gas bubbles – May result from or cause bowel anastomotic leak or fistula □ Fistula may extend to skin or, as sinus tract, to retroperitoneum or body wall Mesenteric adenopathy – Present to some degree in most SB Tx recipients (clusters of mildly enlarged nodes) – Reflects inflammation, infection, or rejection (limited ability to distinguish by imaging)

– Marked or generalized lymphadenopathy suggests additional disease, especially posttransplantation lymphoproliferative disorder (PTLD) ○ Motility disturbance – Denervated bowel often shows some degree of decreased motility – Usually accompanied by generalized dilation of bowel lumen – More severe cases may be suggested by "gasless" SB on plain radiographs (fluid-distended on CT) – Bowel motility can be observed directly by real time US □ Especially useful in children, due to lack of ionizing radiation ○ Posttransplantation lymphoproliferative disorder (PTLD) – More common in SB (up to 30%) and multivisceral Tx than most other solid organ transplant recipients – More common within allografts themselves than in host organs □ Poorly defined hypodense hepatic masses, ± portal adenopathy □ Eccentric SB Tx wall thickening, ± intussusception, obstruction, cavitation ("aneurysmal dilation" of lumen) □ Soft tissue density masses anywhere in body – Only 25% present as markedly enlarged lymph nodes, usually retroperitoneal or generalized, not limited to mesenteric nodes

Imaging Recommendations • Best imaging tool ○ Multiplanar CT, ± CT angiography, displays most important anatomical and pathophysiological information pertinent to small bowel Tx ○ Upper GI series to evaluate motility and status of proximal bowel anastomosis

CLINICAL ISSUES Natural History & Prognosis • SB Tx: 1-year patient survival (90%); graft survival (~ 75%) • Multivisceral Tx: 1-year patient survival (80%) ○ 5-year patient survival: 60% • Worse than for solid organ transplant recipients

DIAGNOSTIC CHECKLIST Consider • Imaging is valuable adjunct ○ Reasonable accuracy for morphologic abnormalities (e.g., vascular, bowel obstruction, abscess, tumor) • Diagnosis of allograft rejection, infection, or ischemia is usually dependent on endoscopy and biopsy

SELECTED REFERENCES 1. 2. 3.

Ruiz P: Updates on acute and chronic rejection in small bowel and multivisceral allografts. Curr Opin Organ Transplant. 19(3):293-302, 2014 van Dijk G et al: Liver, pancreas and small bowel transplantation: current ethical issues. Best Pract Res Clin Gastroenterol. 28(2):281-92, 2014 Selvaggi G et al: Intestinal and multivisceral transplantation: future perspectives. Front Biosci. 12:4742-54, 2007

Small Intestine Transplantation Small Intestine

(Left) Axial NECT shows extensive infiltration of the SB allograft mesentery , along with mural thickening of the bowel wall. Both are common and nonspecific findings in recipients of small bowel transplants. (Right) Axial NECT shows fat-fluid levels that indicate the chylous nature of the loculated ascites interposed between loops of the small bowel allograft. Leakage from SB lymphatics usually resolves over time as the lymphatic connections reform, but may require percutaneous drainage of the fluid.

(Left) NECT shows that the SB allograft is dilated with a thickened wall and pneumatosis , raising concern for infarction of the bowel. (Right) NECT in the same patient shows pneumatosis in an adjacent part of the SB allograft. At endoscopy (through ileostomy), the mucosa appeared normal. Pneumatosis within wall of a small bowel allograft is not rare and may result from infarction, antirejection medications, bowel obstruction, or other "benign" causes.

(Left) Axial CECT in a patient with multivisceral transplant shows the pancreatic and liver allografts. The aortic anastomosis appears to be widely patent. (Right) Volumerendered CT arteriogram in the same patient shows aortic anastomosis . The aortic allograft is kinked or acutely bent back upon itself , which may compromise flow to the allografts. Note the donor SMA supplying the SB allograft, while the donor celiac axis supplies the pancreatic and hepatic allografts.

433

Small Intestine

Intramural (Mesenchymal) Intestinal Tumors KEY FACTS

• Lipoma ○ Most commonly diagnosed benign small bowel (SB) tumor (easy to recognize on CT) ○ Most common cause of SB intussusception (symptomatic) • GI stromal tumor (GIST) ○ Most common type (if duodenum is included) ○ Often large, exophytic, with central necrosis, may communicate with lumen • Leiomyoma ○ Calcifications and necrosis are common (in this rare tumor) • Hemangioma ○ Usually small, ± calcified phleboliths • Neural tumors ○ Schwannoma, paraganglioma, neurofibroma

(Left) CT shows a fat-density mass diagnostic of a lipoma. The mass appears to be intraluminal, due to the effects of chronic peristaltic tugging on the mass, causing it to elongate into an intraluminal polypoid shape. (Right) Axial CECT shows a well-circumscribed mass with heterogeneous enhancement in the pelvis, intimately associated with the adjacent small bowel. This proved to be a leiomyoma of the bowel with necrosis accounting for the heterogeneity.

(Left) A coronal CT section shows a homogeneous, soft tissue density mass within the wall of the duodenum without luminal obstruction. The homogeneous soft tissue density supports the diagnosis of leiomyoma and excludes lipoma, but other masses, such as GI stromal or neural tumors, could have a similar appearance. (Right) Axial CET shows a cylindrical mass within the lumen of the 3rd portion of duodenum, without signs of bowel obstruction. This was a paraganglioma arising from the duodenal wall.

434

○ Multiple SB neurofibromas may be seen in neurofibromatosis type 1 (NF1)

IMAGING

TOP DIFFERENTIAL DIAGNOSES • • • •

Intestinal metastases and lymphoma Small bowel carcinoma Intramural hematoma Ectopic pancreas

CLINICAL ISSUES • Asymptomatic (most common) • GI bleeding, intestinal obstruction, intussusception

DIAGNOSTIC CHECKLIST • Small bowel follow-through: Very low yield procedure to identify small bowel tumors ○ CT enterography is best imaging test ○ Capsule endoscopy or double balloon endoscopy may miss submucosal masses

Ileocecal Valve Lipoma and Lipomatous Infiltration

IMAGING • Lipomatous infiltration of ileocecal valve (ICV): Nonencapsulated proliferation of fat within submucosa of ICV • Barium enema ○ Enlarged ileocecal valve with smooth or lobulated surface contour ○ Stellate folds may radiate into center of mass ○ Oblique images: Terminal ileum entering ICV • CT ○ IC valve leaflets appear thickened with mixed fat/soft tissue density • Lipoma: Benign colonic neoplasm composed of mature fat • Barium enema ○ Smooth, sessile submucosal or polypoid filling defect within colon ○ Soft consistency (compressible; changes shape) ○ Intact, smooth mucosal surface

○ If adjacent to or arising from ICV eccentric mass (not concentric, surrounding valve) • CT is diagnostic ○ Encapsulated, spherical mass of fat within cecum or colon, may be adjacent to ICV

Small Intestine

KEY FACTS

TOP DIFFERENTIAL DIAGNOSES • Colon carcinoma ○ Must be considered in interpretation of barium enema ○ No problem in distinguishing lipoma from carcinoma on CT

PATHOLOGY • Lipoma: Continuing irritation fibrosis and calcification; may ulcerate and bleed • May result in cellular atypia and reactive fibroblasts with mistaken diagnosis of "pseudosarcomatous change"

(Left) Axial CECT shows that both "lips" of the ileocecal valve are prominent and infiltrated by fat , a common finding on CT and usually of no clinical significance. The characteristic appearance of the ICV makes it a useful landmark for the cecum when evaluating RLQ inflammation, such as appendicitis or Crohn disease. (Right) Axial CECT in the same patient shows the terminal ileum entering the colon through the "lips" of the IC valve , which has obvious fat within it.

(Left) Axial CECT shows a small fat-density mass in the cecum, diagnostic of a lipoma. The mass is spherical and arises from, rather than infiltrating the ileocecal valve. (Right) Coronal reformation CECT in the same patient helps to localize the lipoma to the region of the ileocecal valve, which lies at the level of the 1st transverse fold above the cecal tip.

435

Small Intestine

Hamartomatous Polyposis Syndromes KEY FACTS

TERMINOLOGY

PATHOLOGY

• Spectrum of hereditary and nonhereditary polyposis syndromes characterized by gastrointestinal (GI) tract polyps and other associated lesions

• Sessile/pedunculated; carpet-like, clustered, or scattered polyps

IMAGING

• Most common signs/symptoms ○ PJS: Pain, mucocutaneous pigmentation, melena • PJS complications ○ Intussusception, SB obstruction, malignant neoplasms – Bowel > breast > pancreas > reproductive tract – Prognosis: 40% risk of cancer by age 40 • Intestinal polyposis syndromes encompass a wide spectrum of diseases with considerable overlap ○ Gene mutations and phenotypes ○ Polyp histology; disease severity; extraintestinal manifestations ○ Blurs distinction between polyposis syndromes

• Best diagnostic clue ○ Cluster of small filling defects in small bowel with intussusception • Peutz-Jeghers syndrome (PJS) ○ Jejunum and ileum > duodenum > colon > stomach

TOP DIFFERENTIAL DIAGNOSES • • • •

Familial adenomatous polyposis and related syndromes Brunner gland hyperplasia (hamartoma) Lymphoid follicles (hyperplasia) Metastases and lymphoma (GI tract)

(Left) This 28-year-old man has known Peutz-Jeghers syndrome (PJS). A film from a small bowel follow-through shows some of the hundreds of small polyps , presumably hamartomas, throughout his bowel. (Right) Axial CT section in the same patient shows a large mass causing partial obstruction of the duodenum. The mass proved to be a metastasis from a testicular nonseminomatous germ cell tumor.

(Left) Another CT section from the same patient shows 2 segmental, nonobstructing intussusceptions , probably due to the hamartomatous polyps. (Right) Another CT section in the same patient shows some of the innumerable small bowel polyps . As illustrated by this case, some patients with PJS may develop malignant tumors, not just of the bowel, but also of the breast, pancreas, or reproductive tract.

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CLINICAL ISSUES

Hamartomatous Polyposis Syndromes

Abbreviations • • • •

Peutz-Jeghers syndrome (PJS) Multiple hamartoma (Cowden) syndrome (MHS) Juvenile polyposis (JP) Cronkhite-Canada syndrome (CCS)

Staging, Grading, & Classification

• Best diagnostic clue ○ PJS: Cluster of small filling defects in small bowel (SB) with intussusception • Location ○ PJS: Jejunum and ileum > duodenum > colon > stomach ○ MHS + JP: Most polyps in rectosigmoid colon ○ CCS: Stomach (100%), colon (100%), SB (50%)

• Classification: Hamartomatous polyposis syndromes ○ PJS: Autosomal dominant (AD) – Hamartomatous GI tract polyps, mucocutaneous pigmentation of lips, oral mucosa, palms, and soles ○ MHS (Cowden): AD genodermatosis – Mucocutaneous: Facial papules, oral papillomas, keratosis – Breast: Fibrocystic (50%), ductal-type cancer (30%) – Thyroid (65%): Adenomas, goiter, follicular cancer – Pancreatic ductal and intraductal papillary mucinous (IPMN) tumors ○ Juvenile polyposis: 2types – Isolated juvenile polyps of childhood (nonhereditary) – JP of colon or entire GI tract (autosomal dominant) ○ Cronkite-Canada: Inflammatory polyps with ectodermal defects

Radiographic Findings

Gross Pathologic & Surgical Features

• Fluoroscopic-guided double-contrast studies ○ Multiple, variably sized radiolucent filling defects • Polyps in PJS occur from stomach to rectum; mouth and esophagus spared ○ SB involved in 95% – Usually multiple, broad-based polyps – Clustered appearance more than carpeting bowel

• Sessile/pedunculated; carpet-like, clustered, or scattered polyps

Definitions • Spectrum of hereditary and nonhereditary polyposis syndromes characterized by gastrointestinal (GI) tract polyps and other associated lesions

IMAGING General Features

Imaging Recommendations • Best imaging tool ○ Double-contrast barium studies (multiple views) ○ CT enterography

DIFFERENTIAL DIAGNOSIS Familial Adenomatous Polyposis and Related Syndromes • Hundreds or thousands of polyps carpeting colonic mucosa • Tubular or tubulovillous; colorectal cancer risk 100%

Brunner Gland Hyperplasia (Hamartoma) • Duodenal bulb and descending duodenum • Hyperplasia: Multiple nodules ("Swiss cheese" pattern)

Metastases and Lymphoma (GI Tract) • Rarely as numerous as in polyposis syndromes

PATHOLOGY General Features • Etiology ○ Hereditary autosomal dominant (AD): PJS, MHS, only 25% of juvenile polyposis cases ○ Nonhereditary: CCS, 75% of juvenile polyposis cases • Genetics ○ Spontaneous mutation of gene on chromosome 19 (PJS) and 10 (MHS) ○ PTEN is a tumor suppressor gene

Small Intestine

○ Loss or mutation associated with variety of rare syndromes known collectively as PTEN hamartoma tumor syndromes – Includes Cowden (MHS), and Bannayan-RileyRuvalcaba syndromes

TERMINOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ PJS: Pain, mucocutaneous pigmentation, melena

Demographics • Age ○ PJS (10-30), MHS (30-40), CCS (> 60) years • Epidemiology ○ PJS = 1:10,000

Natural History & Prognosis • PJS complications: Intussusception, SB obstruction, malignant neoplasms ○ Bowel > breast > pancreas > reproductive tract • Prognosis: 40% risk of cancer by age 40 • Intestinal polyposis syndromes encompass wide spectrum of diseases with considerable overlap ○ Gene mutations and phenotypes ○ Polyp histology; disease severity; extraintestinal manifestations ○ Blurs distinction between polyposis syndromes

Treatment • Follow-up and surveillance; surgery for malignant neoplasms

SELECTED REFERENCES 1.

Kobayashi Y et al: A tumor of the uterine cervix with a complex histology in a Peutz-Jeghers syndrome patient with genomic deletion of the STK11 exon 1 region. Future Oncol. 10(2):171-7, 2014

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Small Intestine

Carcinoid Tumor KEY FACTS

TERMINOLOGY

IMAGING

• Well-differentiated neuroendocrine tumor usually originating in digestive tract ○ Or, less commonly, lung or genitourinary tract • Midgut carcinoids (jejunoileal) (45%) ○ 90% arise in ileum, within 60 cm of ileocecal valve ○ Account for most cases of carcinoid syndrome • Gastric carcinoids (7%) are associated with chronic stimulation by high serum gastrin levels • Appendiceal carcinoids (16%) ○ Usually found incidentally at appendectomy • Colorectal (31%) ○ Usually asymptomatic until large • Carcinoid syndrome = metastatic spread to liver ○ Spectrum of symptoms (flushing, diarrhea, asthma, pain, right heart failure)

• Protocol: Multiplanar, multiphasic CT (or MR) with enteric water • Solitary, enhancing distal ileal mass with mesenteric metastases • More difficult to detect primary than metastatic foci ○ Mesenteric mass due to direct invasion or nodal metastasis ○ Calcification within mesenteric mass (up to 70% of cases) ○ Tumor may show spiculation with stellate pattern ○ ± tethering, fixation, retraction of small bowel loops ○ ± encasement and narrowing of mesenteric vessels • Liver metastases: Arterial phase; intense enhancement ( vascularity) ○ Washout on portal venous and delayed phases

TOP DIFFERENTIAL DIAGNOSES • Sclerosing mesenteritis • Gastrointestinal stromal tumor

(Left) Arterial phase axial CECT in a 66-year-old man with carcinoid syndrome shows innumerable hypervascular metastases within the liver. (Right) Venous phase CT section in the same patient shows washout of enhancement within the hepatic metastases .

(Left) Also evident in this axial CT of the same patient is a mesenteric mass and paraaortic tissue, representing metastases. Note the tethered appearance and submucosal edema of the distal small bowel, due to the desmoplastic effect on the mesentery and constriction of mesenteric lymphatics and veins that are characteristic of a carcinoid tumor. (Right) Axial CECT in the same patient shows a more discrete mass at the base of the mesentery, which has the typical spiculated appearance of a carcinoid metastasis.

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Carcinoid Tumor

Definitions • Well-differentiated neuroendocrine tumor originating in the digestive tract ○ Or, less commonly, lung or genitourinary tract

IMAGING General Features • Best diagnostic clue ○ Solitary, enhancing distal ileal mass with mesenteric metastases • Location ○ GI tract (55%), bronchopulmonary (30%); genitourinary, and other (15%) ○ GI carcinoids: Small bowel (SB) (45%), rectum (20%), appendix (16%), colon (11%), stomach (7%) ○ Duodenal carcinoids are classified as neuroendocrine tumors along with those arising in pancreas • Size ○ Varies from < 1 cm to a few cm • Other general features • Gastric carcinoids are associated with chronic stimulation by high serum gastrin levels ○ Gastrinoma (Zollinger-Ellison or MEN1 syndrome) ○ Pernicious anemia or atrophic gastritis ○ Gastric carcinoids are often multiple • Midgut carcinoids (jejunoileal) ○ Now more common than adenocarcinoma of SB ○ 75% are solitary ○ 90% arise in ileum, within 60 cm of ileocecal valve • Appendiceal carcinoids ○ Most common tumor of appendix ○ Usually found incidentally at appendectomy • Colorectal ○ Usually asymptomatic until large ○ Rarely cause carcinoid syndrome • Key concepts ○ Carcinoid syndrome – Spectrum of symptoms (flushing, diarrhea, asthma, pain, right heart failure) – Often misdiagnosed for years – Indicates hepatic metastases, usually from SB tumor ○ Symptoms require systemic circulation of hormonal factors produced by carcinoid – Serotonin, histamine, dopamine, somatostatin – Vasoactive intestinal polypeptide, substance P

Radiographic Findings • Fluoroscopic-guided SB series or enteroclysis ○ Mesenteric infiltration: SB loops show angulation, tethering, fixation, and retraction

CT Findings • Submucosal tumors ○ Solitary or multiple, well-defined, enhancing lesions – 80-95% of carcinoids are hypervascular ○ Better visualization of enhancing mural mass with enteric water as contrast agent

○ More difficult to detect primary than metastatic foci • Mesenteric extension of SB tumor ○ Heterogeneous mesenteric mass due to direct invasion or nodal metastasis ○ Calcification within mesenteric mass (up to 70%) ○ Tumor may show spiculation with stellate pattern ○ ± tethering, fixation, retraction of SB loops – Due to mesenteric fibrosis and desmoplastic reaction – Desmoplastic reaction: Finger-like projections of mass into adjacent mesentery ○ ± encasement and narrowing of mesenteric vessels ○ SB obstruction may occur from luminal mass, kinking of bowel, or intussusception • Liver metastases ○ Arterial phase: Intense enhancement ( vascularity) ○ Delayed imaging: Iso- to hypodense to liver • 3D CT angiography ○ Detects mesenteric mass and its relationship to vessels ○ Shows encasement or occlusion of mesenteric vessels ○ ± bowel wall thickening and submucosal edema – Due to ischemia or engorgement of involved SB loops

Small Intestine

TERMINOLOGY

MR Findings • Submucosal SB tumor ○ T1WI: Isointense to muscle ○ T2WI: Hyperintense or isointense to muscle ○ T1 C+: Homogeneous enhancement • Mesenteric extension of tumor ○ T1WI and T2WI – Mass and spiculation: Isointense to muscle – Desmoplastic strands: Hypointense – Calcification: Cannot be detected ○ T1 C+: Shows intense enhancement • Liver metastases ○ T1WI: Hypointense ○ T2WI: Mild to moderately hyperintense ○ Arterial phase: Homogeneous enhancement ○ Portal venous phase: Isointense to liver ○ Larger metastases: Heterogeneous enhancement – Due to areas of necrosis ○ Occasionally enhancement may be peripheral, with progressive fill-in on delayed imaging

Nuclear Medicine Findings • In-111 octreotide or somatostatin receptor scintigraphy (Octreoscan) ○ Provides whole-body scanning ○ Best performed with SPECT technique ○ Less sensitive for primary tumor and liver metastases than CT or MR • Whole-body F-18 dopa PET ○ Detects primary tumor, nodal, and distant organ metastases by increased uptake • I-131 labeled MIBG ○ uptake by GI tract, nodal, and liver metastases

Imaging Recommendations • Multiplanar CECT (or MR) with enteric water ○ Arterial (~ 35 seconds) and venous phase (~ 70-second delay) • In-111octreotide or somatostatin receptor scintigraphy 439

Small Intestine

Carcinoid Tumor ○ Sensitivity (75%), specificity (100%)

DIFFERENTIAL DIAGNOSIS Sclerosing Mesenteritis • Cluster of nodes; perivascular fat "halo" • Infiltrated jejunal mesentery (not ileal)

Gastrointestinal Stromal Tumor (GIST) • Hypervascular tumor, not associated with desmoplastic effect on mesentery

Small Bowel Carcinoma • More common in duodenum or jejunum than in ileum • Causes luminal obstruction • Mass and metastases are hypovascular

Intestinal Metastases and Lymphoma • Generally less vascular and less likely to induce desmoplastic response in mesentery

PATHOLOGY General Features • Etiology ○ Traditional classification based on origin from embryologic alimentary tract – Foregut (bronchus, stomach, duodenum) – Midgut (SB, appendix, proximal colon) – Hindgut (distal colon, rectum, genitourinary) ○ Arise from enterochromaffin cells of Kulchitsky in crypts of Lieberkühn ○ Cells stain with potassium chromate, indicating presence of serotonin • Associated abnormalities ○ Cardiac abnormalities (incidence: 60-70%) – Pulmonary and tricuspid stenosis or insufficiency – Enlargement of right heart and septal irregularities ○ May be associated with other malignant neoplasms – Belong to tumors called apudomas (amine precursor uptake and decarboxylation tumors)

Gross Pathologic & Surgical Features • Firm, yellow, submucosal nodules

Microscopic Features • • • •

Small round cells, round nucleus, clear cytoplasm Tumor infiltration along neurovascular bundles Desmoplastic, fibrotic, retractile reaction On electron microscopy: Neuron-specific enolase granules = "neuroendocrine" • Poorly differentiated tumors are not called "carcinoid" ○ These are aggressive NETs that resemble small cell lung cancer and have aggressive clinical course

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Usually asymptomatic until metastases occur ○ Some patients are symptomatic for 2-7 years before diagnosis made

440

○ Carcinoid syndrome: Episodic cutaneous flushing, wheezing, and diarrhea – Implies liver metastases with subsequent systemic venous drainage of carcinoid secretory factors ○ Other signs/symptoms – Abdominal pain: Secondary to intestinal obstruction or ischemia □ Obstruction usually caused by mesenteric kinking and distortion – Right heart failure and murmurs (valvular defects) • Lab data ○ blood levels of serotonin or 5 hydroxytryptophan ○ 24-hour urine: Increased 5-HIAA levels (5x normal)

Demographics • Age ○ Most occur in 5th or 6th decade of life • Gender ○ M:F = 2:1 • Epidemiology ○ Rare (accounts 2% of GI tract tumors), but increasing in incidence ○ Affects 2-5 per 100,000 in North America and Europe

Natural History & Prognosis • SB carcinoid with no lymph node or liver metastases ○ Excellent prognosis with surgical resection ○ 5-year survival rate for SB carcinoids is 90% • 5-year survival rate with hepatic metastases (50%) ○ Can be prolonged with treatment of liver metastases – e.g., transcatheter chemoembolization

Treatment • Distal SB tumors: Surgical resection of bowel and mesentery often with right hemicolectomy • Duodenal tumors ○ Pancreaticoduodenectomy (Whipple procedure) • Liver metastases ○ Localized to single segment/lobe: Surgical resection ○ Chemoembolization; radiofrequency ablation • Somatostatin analogue: Octreotide relieves symptoms • Systemic chemotherapy: No role, except for bone metastases

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Mesenteric, discrete, enhancing mass with calcification, desmoplastic reaction ± liver metastases

SELECTED REFERENCES 1.

2.

Tsai SD et al: Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation. Abdom Imaging. ePub, 2014 Horton KM et al: Carcinoid tumors of the small bowel: a multitechnique imaging approach. AJR Am J Roentgenol. 182(3):559-67, 2004

Carcinoid Tumor Small Intestine

(Left) Axial CECT in a 65-yearold man with abdominal pain shows a mesenteric mass with central calcification and engorged blood vessels within the mesentery. There is stranding of the mesentery and tethering of the bowel in the right lower quadrant. (Right) Venous phase CT in the same patient shows an equivocal mass in the ileocecal area, which was confirmed as a carcinoid at surgery. As is typical, the mesenteric metastasis was more evident on CT than the primary tumor, especially on venous phase CECT.

(Left) This 54-year-old man had crampy abdominal pain and flushing. Axial CT shows hypervascular hepatic and peritoneal metastases . (Right) Coronal reformatted CT in the same patient shows a hypervascular mass in the terminal ileum (primary carcinoid) with mesenteric metastases having a desmoplastic effect on the ileal mesentery. These are classic clinical and imaging features of carcinoid syndrome.

(Left) Arterial phase axial CECT in a 75-year-old man demonstrates a markedly hypervascular mass in the gastrohepatic ligament directly abutting the lesser curvature of the stomach. (Right) Coronal volumerendered CECT in the same patient nicely demonstrates that this mass is directly contiguous with the wall of the stomach . This was found to be an exophytic gastric carcinoid tumor at surgical resection. A gastric GIST could have a similar appearance.

441

Small Intestine

Small Bowel Carcinoma KEY FACTS

TERMINOLOGY • Primary adenocarcinoma of small intestine (excluding duodenum) ○ Duodenal carcinoma has more in common with gastric cancer ○ Small bowel (SB) carcinoma has more in common with colon carcinoma

IMAGING • Most commonly in jejunum, within 30 cm of ligament of Treitz ○ Duodenum is more common location, but often considered as a separate entity • Infiltrating tumor: "Apple core" or annular lesion ○ Short, well-demarcated, circumferential narrowing ○ Irregular lumen, overhanging edges, ± ulceration ○ Narrow, rigid stricture with prestenotic dilatation • Polypoid sessile tumor: Small plaque-like growth • Often presents with intussusception

(Left) Axial CECT in a 47-yearold woman demonstrates mass-like wall thickening of the proximal jejunum. (Right) Coronal CECT in the same patient demonstrates the focal wall thickening in the jejunum . Note the fluidfilled distension of the duodenum and stomach, secondary to bowel obstruction by the mass. This was found to be a jejunal adenocarcinoma at surgical resection.

(Left) Spot film from a small bowel follow-through (SBFT) shows an "apple core" stricture of the terminal ileum with luminal narrowing, mucosal destruction, and overhanging margins . These are classic features of a primary SB carcinoma. (Right) Spot film from a SBFT shows a jejunal mass with nodular thickened folds, mucosal destruction, and luminal narrowing, characteristic findings of a primary SB carcinoma. The bowel upstream from this tumor is dilated .

442

• ± enlarged mesenteric nodes; perivascular invasion • ± metastases: Liver, peritoneal surfaces, ovaries

TOP DIFFERENTIAL DIAGNOSES • Intestinal metastases and lymphoma ○ NHL: Bulky mass with lymphadenopathy ○ Metastases: Multiple, from melanoma, lung, breast, etc. • Intestinal GIST ○ Usually larger, more exophytic mass • Carcinoid tumor ○ Hypervascular submucosal mass, ileal mesenteric invasion • Crohn disease

PATHOLOGY • Celiac and Crohn disease, polyposis syndromes increase risk of SB carcinoma

CLINICAL ISSUES • Malignant tumors of SB are < 2% of all GI tumors

Small Bowel Carcinoma

Definitions • Primary adenocarcinoma of small intestine (excluding duodenum) ○ Duodenal carcinoma has more in common with gastric cancer ○ Small bowel (SB) carcinoma has more in common with colon carcinoma

IMAGING General Features • Best diagnostic clue ○ Annular or eccentric mass causing intussusception or obstruction • Location ○ Jejunum, within 30 cm of ligament of Treitz – Ileum (< 15%) ○ Duodenum: Most common (> 50%) if included within definition of small bowel

Radiographic Findings • Fluoroscopic-guided enteroclysis ○ Infiltrating tumor: "Apple core" or annular lesion – Short, well-demarcated, circumferential narrowing – Irregular lumen, overhanging edges, ± ulceration – Narrow, rigid stricture with prestenotic dilatation ○ Polypoid sessile tumor: Small plaque-like growth ○ Pedunculated polypoid adenocarcinoma (rare)

CT Findings • • • • • • •

Annular, ulcerative lesion or discrete nodular mass Circumferential thickened wall ± mesenteric invasion Soft tissue mass ± luminal narrowing and obstruction Often presents with intussusception ± enlarged mesenteric nodes; perivascular invasion Tumor shows moderate enhancement on CECT ± metastases: Liver, peritoneal surfaces, ovaries

Imaging Recommendations • Best imaging tool ○ Fluoroscopic or CT enteroclysis; multiplanar CT

DIFFERENTIAL DIAGNOSIS Intestinal Metastases and Lymphoma • Lymphoma ○ Bulky mass; luminal narrowing or aneurysmal dilation ○ Usually with large mesenteric nodes • Metastases ○ Usually from melanoma, lung, breast, or cervix ○ Usually multiple and in patient with known cancer

Intestinal GIST • Larger, more exophytic mass with central necrosis • Mucosa may be intact or ulcerated • May cavitate, ± aneurysmal dilation of lumen

Carcinoid Tumor

• Mesenteric mass: Calcification and desmoplastic reaction • More common in ileum

Crohn Disease • Usually distal ileum with long segment of wall thickening • Mucosal hyperenhancement, submucosal edema • Skip lesions, transmural, fistulas, sinuses, fissures

Small Intestine

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ Most probably arise from adenoma (adenoma-carcinoma sequence, as with colorectal carcinoma) • Genetics ○ Mutations of key regulatory genes (KRAS and TP53) • Associated abnormalities ○ Adult celiac disease, Crohn disease, Peutz-Jeghers syndrome, polyposis syndromes, hereditary nonpolyposis colorectal cancer – All associated with prevalence of SB carcinoma – Hereditary syndromes convey ~ 100x increased risk

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, obstruction, or both (90%) ○ Bleeding or anemia (50%)

Demographics • Age: Usually seen in older age group (50-70) • Gender: M > F (1.4:1) • Epidemiology ○ Prevalence: 0.5-3/100,000 population ○ 2/3 of all SB neoplasms are malignant ○ Malignant tumors of SB are < 2% of all GI tumors – Carcinoma (25-40%), carcinoid (30-40%), GIST (1015%), lymphoma (primary to SB) (10-15%) ○ Colon carcinoma is 50x more common than SBC

Natural History & Prognosis • Complications ○ SBO, intussusception, GI bleed, perforation (rarely) ○ Metastases (liver, lung, bone, brain) • Prognosis ○ 5-year survival: Jejunal cancer (46%), ileal (20%)

Treatment • Surgical resection (localized), chemotherapy (spread)

SELECTED REFERENCES 1. 2. 3.

4.

Guo XC et al: Retrospective analysis of 119 small bowel adenocarcinoma in Chinese patients. Cancer Invest. 32(5):178-83, 2014 Ynson ML et al: What are the latest pharmacotherapy options for small bowel adenocarcinoma? Expert Opin Pharmacother. 15(6):745-8, 2014 Chua TC et al: Cytoreductive surgery and perioperative intraperitoneal chemotherapy for peritoneal carcinomatosis from small bowel adenocarcinoma. J Surg Oncol. 100(2):139-43, 2009 Horton KM et al: Multidetector-row computed tomography and 3dimensional computed tomography imaging of small bowel neoplasms: current concept in diagnosis. J Comput Assist Tomogr. 28(1):106-16, 2004

• Hypervascular submucosal mass; mesenteric invasion • Primary often difficult to detect; metastases more obvious 443

Small Intestine

Intestinal Metastases and Lymphoma KEY FACTS

TERMINOLOGY • Intestinal metastases from extraintestinal primary cancer • Primary small bowel (SB) lymphoma ○ Limited to bowel ± mesenteric nodes • Secondary lymphoma ○ Involvement of spleen, liver, or thoracic nodes

IMAGING • Intestinal metastases • Malignant melanoma is most common primary site ○ Enhancing masses within SB mesentery and bowel wall ○ Bull's-eye or "target" lesions; intussusception • Lung and breast carcinoma metastases ○ Are scirrhous tumors ○ Likely to cause luminal obstruction • Intraperitoneal metastatic spread (e.g., from ovarian and GI primary tumors) ○ Serosal metastases cause clustered adhesion and fixation of SB loops and functional obstruction

(Left) Axial CECT in a 58-yearold man who presented with a known history of malignant melanoma demonstrates 1 of several soft tissue masses in the mesentery. The metastases subsequently resulted in an intussusception. (Right) Axial CECT in the same patient 5 months later reveals the resultant long-segment intussusception . One of the bowel wall metastases served as the lead point of the intussusception.

(Left) Axial CECT in a 46-yearold man who presented with a known history of non-Hodgkin lymphoma demonstrates extensive, multifocal, bowel wall thickening and aneurysmal dilatation of the lumen of the ileum . (Right) Coronal CECT reconstruction in the same patient illustrates extensive mesenteric lymphadenopathy and encasement of the mesenteric vessels, but no bowel or vascular obstruction. Multifocal masses of lymphoma are also seen.

444

• Intestinal lymphoma • Circumferential type: Sausage-shaped mass(es) ○ Rarely obstructs; may cause aneurysmal dilation • Polypoid form: Bull's-eye or "target" lesions • Mesenteric form: SB masses and nodes

TOP DIFFERENTIAL DIAGNOSES • Primary small bowel carcinoma ○ Solitary mass causing luminal obstruction • Infectious and inflammatory etiologies ○ Mucosal hyperenhancement and submucosal edema

CLINICAL ISSUES • Metastases: Most common with melanoma > lung, breast, others ○ May arise many years after primary tumor removal • Lymphoma accounts for 1/2 of all malignant SB tumors ○ Patients with immune suppression (e.g., transplant recipients, AIDS); celiac disease

Intestinal Metastases and Lymphoma

Definitions • Intestinal metastases from extraintestinal primary cancer • Lymphoma: Malignant tumor of B lymphocytes ○ Primary small bowel (SB) lymphoma: Limited to bowel ± mesenteric nodes ○ Secondary or generalized lymphoma: Involvement of spleen, liver, or thoracic nodes

IMAGING Radiographic Findings • Metastases to bowel • Barium-enhanced fluoroscopic studies (upper GI, SB followthrough, barium enema) ○ Most detailed study of SB is enteroclysis (tube administration of barium into SB with distention of lumen) ○ Offer detailed view of mucosal and intramural extent of disease – Less useful for extrinsic, extraluminal disease • Malignant melanoma metastases to SB ○ Solitary or multiple discrete submucosal masses ○ Bull's-eye or "target" lesions: Centrally ulcerated submucosal masses • Lung and breast carcinoma metastases ○ Are scirrhous tumors; likely to cause luminal obstruction • Intraperitoneal metastatic spread (e.g., from ovarian and GI primary tumors) ○ Serosal metastases cause clustered adhesion and fixation of SB loops and functional obstruction ○ Lack of peristalsis through affected segments • Intestinal lymphoma ○ Multifocal intramural and mesenteric masses without SB obstruction ○ Splenic and hepatic enlargement or focal masses ○ Infiltrating lymphoma (most frequent) – Circumferential thickening and effacement of folds – Lumen may be compressed or dilated (aneurysmal dilation) □ Due to replacement of muscularis propria by lymphoma □ Lymphoma is not likely to cause high-grade bowel obstruction ○ Polypoid lymphoma – Single/multiple, mucosal/submucosal masses – "Target" or Bull's-eye lesions ( if centrally ulcerated) – Rarely lymphomatous polyposis (follicular mantle cell origin) ○ Nodular lymphoma – Multiple small submucosal nodular defects ○ Endoexoenteric (cavitary form): Localized perforation into extraluminal tissue – Barium, air, and debris fill cavity along mesenteric border of SB – ± ulcer, fistulas, aneurysmal dilatation

CT Findings • Demonstration of lesions is facilitated by distention of SB with water

○ CT enterography is best protocol, with multiplanar reformation • Intestinal metastases ○ Malignant melanoma – Bull's-eye or "target" lesions (discrete mural nodules) □ Enhancing mural nodules protruding into lumen, focal thickening of intestinal wall – Enhancing masses within SB mesentery, abdominal viscera, etc. – Lobulated submucosal or giant cavitated lesions (aneurysmal dilation) – Nonobstructive, large intramural mass favors melanoma or lymphoma over carcinoma – May be lead point in intussusception ○ Lung and breast carcinoma metastases – Flat or polypoid intramural masses that compress or obstruct bowel lumen – Mimic primary SB carcinoma ○ Direct invasion – Pancreatic head cancer: Mural thickening or circumferential narrowing of duodenal lumen – Gynecologic cancer: Distal ileal involvement ○ Intraperitoneal metastases – Serosal metastases: Clustered SB loops adherent to each other – Functional or mechanical SBO – "Stellate" appearance: Mesenteric fat infiltration – Ovarian carcinoma: Mesenteric/omental and mural intestinal masses + solid/cystic pelvic mass (± foci of calcification) • Intestinal lymphoma ○ Infiltrating form most common – Circumferential type: Sausage-shaped mass of homogeneous density; minimal enhancement – Aneurysmal dilation of SB lumen ○ Polypoid form: Bull's-eye or "target" lesions ○ Mesenteric form – Retroperitoneal and mesenteric adenopathy favors lymphoma as diagnosis – Sandwich sign: Mildly enhancing, multiple discrete or confluent masses encasing mesenteric vessels

Small Intestine

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CT enterography with multiplanar reformations for total extent of disease ○ Fluoroscopic-guided enteroclysis for mucosal and subtle intramural disease

DIFFERENTIAL DIAGNOSIS Primary Small Bowel Carcinoma • Solitary SB mass with SBO as presenting symptom

Hemorrhage • Due to warfarin (Coumadin), trauma • Localized bleeding may be seen as intramural mass

Vasculitis (Small Intestine) • Vasculitis causes mucosal hyperenhancement and submucosal edema, not seen with neoplastic wall thickening 445

Small Intestine

Intestinal Metastases and Lymphoma

• Segmental mucosal hyperenhancement and submucosal edema • Mesenteric adenopathy, fibrofatty proliferation

Other Inflammatory (Whipple Disease) • Thickened proximal SB folds, thickened mesentery, lymphadenopathy • Micronodules in jejunum on enteroclysis

PATHOLOGY General Features • Etiology ○ Intestinal metastases – Malignant melanoma more common than breast, lung, ovarian cancer – Appendix, colon, pancreatic cancer; carcinoid are reported rarely ○ Intestinal lymphoma – Primary: Non-Hodgkin (B-cell) most common □ High grade of large cell or immunoblastic cell types; 30-50% harbor disease in mesenteric lymph nodes – Secondary: Generalized lymphoma □ Bowel is just 1 of multiple sites of involvement – Enteropathy-associated lymphoma: Celiac disease • Associated abnormalities ○ Primary tumor mass in patients with intestinal metastases ○ Generalized adenopathy, splenomegaly in patients with secondary lymphoma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Usually found while staging known primary carcinoma or lymphoma ○ Pain, weight loss, palpable mass; may be asymptomatic ○ Malabsorption, diarrhea ○ Acute abdomen: Obstruction, perforation

Demographics • Age ○ More common in elderly patients ○ Burkitt lymphoma in children involves ileocecal areas • Epidemiology ○ Metastases are most common in patients with melanoma – Lung, breast, and ovarian carcinoma are other common primary sites ○ Intestinal lymphoma – Most common malignant SB tumor, if primary and secondary forms are included □ Lymphoma accounts for 50% of all malignant SB tumors, but only 10-15% of primary SB malignancies – More common in patients with immune suppression (e.g., transplant recipients, AIDS) or celiac disease – SB is 2nd most frequent site of GI tract primary lymphoma 446

□ Stomach (51%), SB (33%), colon (16%), esophagus (< 1%)

Crohn Disease

Natural History & Prognosis • Intestinal metastases ○ Various forms of metastatic spread to intestine – Hematogenous spread □ Melanoma, lung, breast cancer □ SB and mesentery are most common sites of metastases from melanoma after lung and liver □ Breast cancer: Metastasizes to stomach, duodenum, and colon more often than SB □ Breast, lung, and melanoma metastases may arise many years after primary tumor removal – Lymphatic spread: Colon, ovarian, breast, and lung cancer, carcinoid and melanoma – Direct invasion from contiguous neoplasms □ Pancreatic cancer: 2nd and 3rd parts of duodenum □ Cecal and gynecologic cancer: Distal ileum – Intraperitoneal spread or seeding (carcinomatosis) □ Primary mucinous tumors of ovary, appendix, colon □ Due to natural flow and accumulation of ascitic fluid within peritoneal recesses; influences serosal implantation of cancer cells □ Common sites: Ileocecal region, SB mesentery, posterior pelvic cul-de-sac • Complications: Bleeding, perforation, obstruction • Prognosis: Poor

Treatment • Surgical resection of lesions that bleed, perforate, obstruct, or have aneurysmal dilation

DIAGNOSTIC CHECKLIST Consider • Check for history of primary cancer or immune suppression

Image Interpretation Pearls • Overlapping radiographic features of intestinal metastases, lymphoma, and primary carcinoma • Imaging is important to suggest and stage malignancy

SELECTED REFERENCES 1. 2. 3. 4. 5. 6.

Baderca F et al: Mucosal melanomas in the elderly: challenging cases and review of the literature. Clin Interv Aging. 9:929-37, 2014 Ilus T et al: Incidence of malignancies in diagnosed celiac patients: a population-based estimate. Am J Gastroenterol. 109(9):1471-7, 2014 Masselli G et al: Small-bowel neoplasms: prospective evaluation of MR enteroclysis. Radiology. 251(3):743-50, 2009 Buckley O et al: The imaging of coeliac disease and its complications. Eur J Radiol. 65(3):483-90, 2008 Sailer J et al: MDCT of small bowel tumours. Cancer Imaging. 7:224-33, 2007 Gore RM et al: Diagnosis and staging of small bowel tumours. Cancer Imaging. 6:209-12, 2006

Intestinal Metastases and Lymphoma Small Intestine

(Left) Axial CECT in a 69-yearold man who presented with a known history of metastatic melanoma demonstrates classic widespread metastases from melanoma, including the gastric wall and lymph nodes . The gastric wall metastases may ulcerate, leading to the classic "target" or bull's-eye appearance. (Right) CT in the same patient shows widespread metastases, including the small bowel , lymph nodes, and omentum , with both nodular and diffuse metastases seen. The right ureter was obstructed due to a ureteral metastasis.

(Left) This elderly man presented with fever, night sweats, and weight loss. A coronal-reformatted CT shows soft tissue masses enveloping, but not obstructing, small bowel and mesenteric vessels. (Right) Another coronal section in this patient shows more of the dominant mass along with extensive mesenteric lymphadenopathy . NonHodgkin lymphoma was confirmed.

(Left) Axial CECT in a patient with melanoma, weight loss, and diarrhea shows large, ulcerated masses with aneurysmal dilation of the small intestine lumen; however, no intestinal obstruction is seen. (Right) Axial CECT in a woman with a history of breast cancer shows dilation of the stomach and duodenum, with abrupt narrowing of the 3rd portion of the duodenum . An intramural mass is constricting the lumen of the duodenum. At surgery, metastatic breast cancer was confirmed.

447

Small Intestine

Intestinal GIST KEY FACTS

TERMINOLOGY

• Lymphatic spread is rare

• Mesenchymal tumor of GI tract derived from interstitial cells of Cajal

TOP DIFFERENTIAL DIAGNOSES

IMAGING • Most common mesenchymal neoplasm in SB ○ Duodenum (25-50%) ○ Jejunum (25-50%) ○ Ileum (25%) ○ Colonic GIST is rare • CT enterography: Best imaging test for diagnosis ○ PET/CT: Best for staging • Heterogeneous enhancement with central necrosis • Endoluminal and exophytic mass with smooth border • Ulceration of bowel mucosa (in 50%) ○ Aneurysmal dilatation of small bowel lumen ○ Due to cavitation and apparent luminal enlargement • Small foci of calcification • Liver, omental, and mesenteric metastases are common

(Left) This 71-year-old woman presented with hematochezia. CT enterography shows a brightly enhancing mass that is mostly exophytic and does not obstruct the bowel lumen. Ulceration of the surface of the mass is suggested. Active bleeding into the bowel lumen is seen . (Right) A coronal image in the same patient clearly shows the exophytic nature of the mass and also the active bleeding into the bowel lumen. A GIST was excised from the small bowel.

(Left) Axial CECT in a 81-yearold man with upper abdominal discomfort shows a large mass arising from the duodenum, with foci of necrosis and calcification . (Right) More caudal section in the same patient shows more necrosis within the mass. These findings are typical for GIST, and the small bowel (including the duodenum) is 2nd to the stomach as the most common site for these tumors.

448

• Carcinoid tumor ○ More common than GIST ○ Associated mesenteric metastasis with desmoplastic response • Intestinal metastases and lymphoma ○ More common than intestinal GIST ○ Lymphoma: Bulky mass, sandwich sign, associated retroperitoneal lymph node enlargement

CLINICAL ISSUES • Surgical resection with imatinib medication is effective therapy, but recurrence is common

Intestinal GIST

Abbreviations

• Metastases from colon cancer, melanoma, ovarian cancer

PATHOLOGY

• Gastrointestinal stromal tumor (GIST)

General Features

Definitions

• Etiology ○ Single gene mutation in most cases – Expression of tyrosine kinase growth factor receptor (KIT receptor, CD117) ○ Rare syndromic cases may have other genetic mutations ○ Derived from interstitial cells of Cajal (GI pacemaker cells) • Associated abnormalities ○ Rare association with NF1 (neurofibromatosis) ○ Familial GIST syndrome

• Mesenchymal tumor of GI tract derived from interstitial cells of Cajal

IMAGING General Features • Best diagnostic clue ○ Well-circumscribed mass extending exophytically from GI tract • Location ○ Stomach is most common location for GIST ○ Small bowel is 2nd; distribution of SB GIST – Duodenum (25-50%) – Jejunum (25-50%) – Ileum (25%) – Colonic GIST is rare • Size ○ Varies from few mm to 30 cm ○ Malignant GISTs are usually large (> 5 cm) • Morphology ○ Solitary, well circumscribed, lobulated ○ Submucosal, intraluminal, subserosal, exophytic

Small Intestine

TERMINOLOGY

Staging, Grading, & Classification • Epithelioid or spindle cell type (based on predominant cells) • 20-30% are malignant

Gross Pathologic & Surgical Features • Usually well circumscribed with focal necrosis, hemorrhage

Microscopic Features • Benign or malignant mesenchymal spindle cells or epithelioid neoplasm • Malignant: High mitotic rate, high nuclear grade, high cellularity, invasion of adjacent structures

CLINICAL ISSUES

Imaging Recommendations

Presentation

• Best imaging tool ○ CT enterography with multiplanar reformations

• Most common signs/symptoms ○ Abdominal pain, GI bleeding, obstruction

CT Findings

Demographics

• Endoluminal and exophytic mass with defined border • Heterogeneous enhancement with central necrosis on CT • Aneurysmal dilatation of small bowel lumen ○ Due to cavitation and apparent luminal enlargement • Liver, omental, and mesenteric metastases are common ○ Lymphatic spread is rare • ± direct extension to adjacent structures; vascular encasement

• Age ○ Median is 55 years • Gender ○ M=F • Epidemiology ○ Most common mesenchymal neoplasm in SB ○ Represents 20% of SB neoplasms; 200-500 cases per year in USA

Fluoroscopic Findings

Natural History & Prognosis

• Upper GI ○ Intramural mass with obtuse or right angles with bowel lumen – ± mucosal ulceration, cavitation, aneurysmal dilation

• Poor prognostic factors ○ Size > 5 cm, distal SB location, • 5-year survival: 50-60% • High rate of recurrence

Nuclear Medicine Findings

Treatment

• PET ○ High FDG avidity

• Surgical resection, imatinib therapy

mitotic rate

SELECTED REFERENCES DIFFERENTIAL DIAGNOSIS

1.

Carcinoid Tumor • Usually solitary, well defined, enhancing • Associated mesenteric metastasis with desmoplastic response

2.

Corless CL et al: Pathologic and molecular features correlate with long-term outcome after adjuvant therapy of resected primary GI stromal tumor: the ACOSOG Z9001 trial. J Clin Oncol. 32(15):1563-70, 2014 Tap WD et al: That's the "GIST" of it: use of adjuvant imatinib after resection of a primary GI stromal tumor. J Clin Oncol. 32(15):1543-6, 2014

Intestinal Metastases and Lymphoma • Lymphoma: Bulky mass, sandwich sign, associated retroperitoneal lymph node enlargement 449

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SECTION 7

Colon

Introduction and Overview Imaging Approach to the Colon

452

Infection Infectious Colitis Neutropenic Colitis (Typhlitis)

458 464

,QƮDPPDWLRQDQG,VFKHPLD Ulcerative Colitis Toxic Megacolon Ischemic Colitis Appendicitis Mucocele of the Appendix Colonic Diverticulosis Diverticulitis Epiploic Appendagitis

466 470 474 478 484 488 492 498

Degenerative Sigmoid Volvulus Cecal Volvulus Colonic Ileus and Ogilvie Syndrome Fecal Impaction and Stercoral Ulceration Rectal Prolapse and Intussusception

502 506 508 512 513

Trauma Colorectal Trauma

514

Benign Neoplasms Colonic Polyps Villous Adenoma

516 520

Malignant Neoplasms Colon Carcinoma Rectal Carcinoma Familial Polyposis and Gardner Syndrome Appendiceal Tumors Colonic Metastases and Lymphoma

524 530 534 540 541

Colon

Imaging Approach to the Colon

Embryology and Congenital Malformations The ascending and transverse colon, along with the small intestine, are part of the embryologic midgut, which undergoes marked elongation beginning in the 6th week of fetal development. To accommodate this increased length, the midgut herniates into the base of the umbilical cord. During the 10th week, it returns to the abdomen while undergoing a complex series of rotations and fixations. All portions of the fetal colon are suspended on mesenteries, but the mesenteries of the ascending and descending colon usually fuse to the retroperitoneal fascia, leaving these portions normally covered by peritoneum only on their anterior surface and are thus regarded as retroperitoneal organs. Variations in these embryologic steps are relatively common and may have clinical consequences. Failure of rotation results in the cecum and ascending colon lying on the left side of the abdomen. Accompanying malrotations of the other portions of the midgut may result in neonatal or adult midgut volvulus or adhesive band small bowel obstruction. A left-sided cecum carries with it a left-sided appendix, and appendicitis may present with confusing left lower quadrant pain in these individuals. The cecum and portions of the ascending colon often maintain a mesentery of variable length into adulthood. This makes the cecum more mobile and prone to twist on its mesentery, especially with gaseous distention of its lumen, and may result in cecal volvulus. The sigmoid mesocolon is also often long, with a narrow base of attachment to the posterior abdominal wall, predisposing it to twist. Sigmoid volvulus often obstructs the lumen, compresses blood vessels, and may lead to ischemia and perforation.

Gross Anatomy The cecum is the first part of the colon and is about 7 cm long. It receives the terminal ileum through the ileocecal valve whose "lips" usually contain abundant fat, allowing them to be identified as a useful landmark on CT scans. The appendix is a blind diverticulum, 6-15 cm in length, that has its own mesentery (the mesoappendix). The appendix always arises from the tip of the cecum but may lie in many locations, with over 60% of patients having a retrocecal appendix. The ascending colon extends from the first semilunar fold, at the ileocecal valve, to the transverse colon. Its vascular supply is from the right colic branches of the superior mesenteric artery and vein (SMA and SMV, respectively). The transverse colon includes the "radiologic" hepatic and splenic flexures and is supplied by middle colic branches of the SMA and SMV. The descending colon is supplied by the inferior mesenteric artery and vein (IMA and IMV) and is retroperitoneal. Despite frequent anastomoses between branches of the SMA and IMA, including the marginal artery (of Drummond) and arc of Riolan, the splenic flexure through descending colon is a common site of hypoperfusion and ischemia and may be the result of a congenital deficiency of vascular anastomoses ("watershed area"). The sigmoid colon is quite variable in its length, redundancy, and location. The rectum is the final 15-20 cm of colon. The rectosigmoid junction is usually at the lumbosacral junction and lies in the extraperitoneal pelvis. The rectum has both a mesenteric (superior rectal branches of IMA and IMV) and systemic (middle and inferior rectal branches in the internal 452

iliac vessels) vascular supply. Because of its dual blood supply, rectal carcinoma may metastasize to systemic sites (lungs, bones, etc.) as well as to the liver (via its IMV drainage), while colon carcinoma almost always metastasizes to the liver first.

Mural (Wall) Anatomy The longitudinal layer of muscle in the colon is not as continuous as it is in the small intestine. Instead, it is separated into taeniae, which are 3 thickened, flat bands of smooth muscle. The rectum has a continuous layer of longitudinal muscle, rather than the taeniae. The haustra are sacculations of colon wall caused by contraction of the taenia coli and are separated by the semilunar folds. The rectum has valves, which are analogous to the semilunar folds of the colon. Areas of weakness in the muscular wall are created where the nutrient vessels penetrate. Mucosa and submucosa can herniate through these areas of weakness, resulting in diverticulosis. The colonic submucosa contains numerous, discrete lymphoid follicles that may be apparent as subtle 3-4 mm nodules on a double-contrast barium enema, especially in the right colon. The mucosa, unlike the small intestine, is smooth and not covered with villous projections. Epiploic (omental) appendages (or appendices) are subserosal pockets of fat extending off the colonic surface. These may twist and infarct, causing epiploic appendagitis, with symptoms that mimic those of diverticulitis or appendicitis.

Imaging Issues The double-contrast barium enema, while an excellent study for the diagnosis of colonic diseases, has seen a precipitous decline in use since the advent of colonoscopy, which allows both direct visualization and the ability to biopsy suspicious lesions. CT is the exam of choice for evaluating local invasion and nodal involvement of neoplasms, colonic inflammatory conditions, the mesenteric vasculature, and pericolonic soft tissues. IV contrast medium is very useful to diagnose various ischemic and infectious/inflammatory conditions. Administration of "positive" rectal contrast medium may be useful, especially to diagnose colonic fistulas. CT colonography, in experienced hands, has proven to be an excellent screening modality but is time intensive and requires added expertise in both the performance and interpretation of the study.

Approach to the Abnormal Colon When evaluating a colonic abnormality, the first question to address is whether the lesion is diffuse, segmental, or focal. Wall thickening should be characterized as submucosal edema (infectious, inflammatory or ischemic, never neoplastic), or soft tissue density (less specific, includes possible neoplasm and diverticulitis). Gas density represents pneumatosis, but could represent infarction or several nonischemic causes, including the benign, idiopathic pneumatosis coli. Mucosal lesions form acute borders with the wall and may be pedunculated. Small, solitary mucosal lesions are likely polyps, while a polyposis syndrome should be considered if multiple polyps are present. Large or irregular lesions should raise a suspicion for colon cancer.

Imaging Approach to the Colon

Extrinsic lesions displace bowel and the mass effect creates obtuse borders on contrast studies. Colonic strictures are common, and, like focal lesions, analyzing the appearance will help in formulating a differential. Malignant strictures (e.g., colon cancer) are generally short segment, with abrupt narrowing and overhanging edges ("apple core" lesion). A benign stricture (e.g., postinflammatory or ischemic) is generally longer with smooth, tapered ends. The length and location of colonic involvement is also integral to making the appropriate diagnosis. The most common lesions include: • Colon cancer: Short segment (typically < 10 cm), soft tissue density, may occur anywhere; associated nodal, peritoneal, and hepatic metastases • Diverticulitis: Segmental involvement (typically > 10 cm), most commonly in sigmoid, spares rectum; chronic sequelae include myochosis, a combination of hypertrophy of circular muscle layer, shortening of taeniae, and narrowing of lumen • Ulcerative colitis: Long segment or pancolitis, begins at rectum with contiguous involvement proximally • Crohn (granulomatous) colitis: Variable length segmental involvement with skip areas, terminal ileum usually involved, may see perirectal involvement • Ischemia: Segmental (90%), usually splenic flexure or sigmoid colon, spares rectum • Infectious colitis: Long segment or pancolitis, involves rectum • Neutropenic colitis (typhlitis): Moderate length, involving cecum and ascending colon

Differential Diagnosis Solitary Colonic Filling Defect Common • Colonic polyps • Colon carcinoma • Rectal carcinoma • Villous adenoma • Feces Less Common • Inverted appendiceal stump • Endometrioma • Abdominal abscess • Metastases and lymphoma, colonic • Tuberculoma • Ameboma • Intramural hematoma • Solitary rectal ulcer syndrome • Foreign body • Varix, hemorrhoidal • Diverticulitis • Mesenchymal tumor

Mass or Inflammation of Ileocecal Area Common • Crohn disease • Appendicitis • Prominent ileocecal valve: Lipomatous infiltration of IC valve, lipoma of IC valve • Colon carcinoma • Mesenteric adenitis • Infectious ileocolitis

Colon

Submucosal lesions are found within the bowel wall and form less acute borders ("right angles") with smooth overlying mucosa, although larger lesions can ulcerate. These are much less common than mucosal lesions, with lymphoma being the most common example. A pattern of multiple submucosal filling defects ("thumbprinting") is seen with edema, which may result from an inflammatory, infectious, or ischemic processes.

Less Common • Carcinoid tumor • Cecal diverticulitis • Intestinal metastases and lymphoma • Appendiceal carcinoma • Intussusception • Mucocele of appendix • Typhlitis (neutropenic colitis) • Tuberculosis, colon • Cecal volvulus • Endometriosis • Ischemic colitis Colonic Ileus or Dilation Common • Ileus • Colon carcinoma • Rectal carcinoma • Sigmoid volvulus • Cecal volvulus • Diverticulitis • Ogilvie syndrome • Fecal impaction Less Common • Ischemic colitis • Toxic megacolon • Endocrine disorders • Distended urinary bladder • Neuromuscular disorders Colonic Fistula Common • Diverticulitis • Colonic carcinoma • Cervical carcinoma • Endometrial carcinoma • Ovarian cancer • Cystitis • Bladder instrumentation (mimic) • Postoperative state, bowel Less Common • Crohn disease • Bladder carcinoma • Abscess, abdominal • Infectious colitis • Foreign body • Trauma, colorectal Segmental Colonic Narrowing Common • Colon carcinoma • Diverticulitis • Ischemic colitis • Colonic metastases and lymphoma • Colonic spasm • Infectious colitis 453

Colon

Imaging Approach to the Colon

• Ulcerative colitis • Crohn (granulomatous) colitis Less Common • Pancreatitis • Extrinsic or intramural masses: Endometriosis, uterine fibroid, pericolic abscess • Postoperative stricture • Cathartic abuse • Typhlitis (neutropenic colitis) • Rectal mucosal prolapse • Tuberculosis, colon • Amebic colitis • Radiation colitis • Intramural hematoma, colon Colonic Submucosal Wall Thickening Common • Diverticulitis • Infectious colitis • Ischemic colitis • Portal hypertension • Ulcerative colitis • Crohn disease • Obesity (mimic) Less Common • Colon carcinoma • Typhlitis (neutropenic colitis) • Chemical proctocolitis • Colonic metastases and lymphoma • Intramural hemorrhage • Pneumatosis of intestine • Hemolytic uremic syndrome • Intestinal angioedema Smooth Ahaustral Colon Common • Ulcerative colitis • Cathartic abuse • Crohn disease (granulomatous colitis) • Senescent change, colon • Toxic megacolon Less Common • Ischemic colitis

(Left) Graphic shows a schematic representation of various processes that may narrow the lumen of the colon. Analyzing the borders and placing the lesion in the correct anatomic compartment (mucosal, submucosal, or extrinsic) are the initial steps in developing an appropriate differential diagnosis. (Right) Spot film from a double-contrast barium enema shows a classic "apple core" lesion . Abrupt, short segment narrowing is typical of malignant lesions.

454

• Radiation colitis • Amyloidosis • Schistosomiasis Acute Right Lower Quadrant Pain Common • Appendicitis • Crohn disease • Pelvic inflammatory disease • Pyelonephritis • Urolithiasis (renal calculi) • Mesenteric adenitis Less Common • Diverticulitis • Infectious colitis • Epiploic appendagitis • Omental infarct • Cholecystitis • Gynecologic and obstetric causes: Uterine fibroids, hemorrhagic ovarian cysts, ovarian torsion, endometriosis, ruptured ectopic pregnancy • Ischemic enteritis • Colon carcinoma • Appendiceal carcinoma • Pancreatitis, acute Rare but important • Intussusception • Meckel diverticulitis • Typhlitis (neutropenic colitis) • Mucocele of appendix

Imaging Approach to the Colon Colon

Semilunar folds

Taeniae coli

Ileocecal valve

Epiploic appendage Appendix

Rectal valves Levator ani muscle

Arc of Riolan

Middle colic artery

Marginal artery (of Drummond) Superior mesenteric artery

Right colic artery Left colic artery Ileocolic artery Inferior mesenteric artery

Sigmoid arteries

(Top) Graphic shows the surface and mucosal views of the colon. Three flat bands of smooth muscle, the taeniae coli, run the length of the colon. The semilunar folds lie at right angles to the taenia creating the haustra. (Bottom) The superior mesenteric artery supplies the colon from the appendix through the splenic flexure, with the inferior mesenteric artery supplying the descending colon through the rectum. These arterial branches are highly variable. All are connected by anastomotic arterial arcades and by the marginal artery (of Drummond) and arc of Riolan, which also anastomose with branches of the inferior mesenteric artery that feed the descending and sigmoid colon.

455

Colon

Imaging Approach to the Colon

(Left) Surface-rendered endoluminal view from a CT colonography study shows a pedunculated polyp . This 6 mm lesion was subsequently removed via conventional colonoscopy and found to be a benign adenomatous polyp. (Right) Axial image from the same CT colonography study shows the pedunculated polyp outlined by the insufflated carbon dioxide.

(Left) CT in a 19-year-old man with acute and chronic RLQ pain and a palpable tender mass shows mural thickening of the cecum , with infiltration of the mesentery and enlarged regional nodes . (Right) CT in the same case shows similar mural thickening of the terminal ileum . These are typical features of Crohn disease, confirmed in this case, but infectious enteritis may have a similar appearance.

(Left) CT in an elderly man with acute RLQ pain and a palpable mass shows a dilated appendix , and a circumferential soft tissue density mass in the cecum with extensive invasion into adjacent tissues. (Right) CT in the same case shows an omental soft tissue mass , essentially diagnostic of metastatic malignancy. At surgery, this and the cecal carcinoma were confirmed and resected.

456

Imaging Approach to the Colon Colon

(Left) Coronal CT in a 69-yearold woman with aortic valve disease, hypertension, acute pain, and hematochezia shows low-density wall thickening of the entire descending and sigmoid colon. (Right) Axial CT in the same case shows "thumbprinting" of the sigmoid colon and ascites . The rectum was normal. These are classic clinical and CT features of ischemic (hypoperfusion) colitis.

(Left) An 18-year-old girl (and some friends) had acute onset of profuse, bloody diarrhea after eating hamburgers. Coronal CT shows massive submucosal edema affecting the entire colon, including the rectum. These are classic clinical and imaging features of infectious colitis. Enteropathic Escherichia coli (0157: H7 subtype) was the etiology. (Right) Axial CT in the same case shows fluid distention of a thick-walled rectum . The rectum is rarely involved in ischemic colitis.

(Left) This 50-year-old woman had foul-smelling vaginal discharge. Sagittal CT following rectal administration of contrast medium shows contrast filling the rectum , the vagina , and a colovaginal fistulous tract . The cause was diverticulitis, infecting a hysterectomy scar. (Right) Axial CT in the same case shows adherence of the rectosigmoid colon to the vaginal cuff with contrast filling the vaginal lumen .

457

Colon

Infectious Colitis KEY FACTS

TERMINOLOGY • Colonic inflammation due to bacterial, viral, fungal, or parasitic infections

• Ischemic colitis ○ Usually located in watershed areas, rarely pancolitis ○ Rectum is rarely affected by ischemic colitis

IMAGING

CLINICAL ISSUES

• Best imaging tool: CECT with multiplanar reformations ○ Mucosal hyperenhancement, marked submucosal edema, ascites ○ Multiple air-fluid levels, inflamed pericolonic fat • Clostridium difficile, Campylobacter, Escherichia coli, CMV ○ Accordion sign: Alternating bands of enhancing mucosa and submucosal edema with compressed lumen • May progress to hemorrhagic necrosis and perforation; toxic megacolon

• C. difficile colitis occurs mostly in institutionalized patients or those on antibiotic, chemotherapy, or immunosuppressive medication • Acute infectious diarrhea is most often foodborne or waterborne disease • Most common bacterial causes of infectious colitis in USA ○ C. difficile, Salmonella, Campylobacter, and E. coli • Symptoms: Watery or bloody diarrhea, fever ○ Painful abdominal cramps and tenderness ○ Usually acute onset, except TB (chronic) • Diagnosis: Stool cultures, blood cultures, endoscopic biopsy, serology studies • Often self-limited or responsive to antimicrobial therapy in previously healthy patients

TOP DIFFERENTIAL DIAGNOSES • Ulcerative colitis ○ Wall thickening is generally less prominent with UC • Granulomatous colitis (Crohn disease)

(Left) Graphic illustration demonstrates pancolitis with marked mural thickening and multiple elevated yellowwhite plaques, or pseudomembranes, typical for Clostridium difficile colitis (Right) Axial CECT in a 62year-old man who presented with diarrhea and dehydration demonstrates a classic case of pseudomembranous (C. difficile) colitis. Note the severe bowel wall thickening throughout the entire colon , and ascites. C. difficile colitis typically presents as a pancolitis, as in this example.

(Left) A 71-year-old woman had a history of recent antibiotic use for cellulitis and presented with nausea, vomiting, and diarrhea. Axial CT shows moderate diffuse bowel wall thickening and hyperemia of the entire colon and rectum. (Right) Coronal CECT in the same patient again illustrates moderate diffuse bowel wall thickening of the entire colon. C. difficile (pseudomembranous) colitis was confirmed.

458

Infectious Colitis

Definitions • Colonic inflammation due to bacterial, viral, fungal, or parasitic infections • Pseudomembranous colitis: Descriptive term usually applied to Clostridium difficile colitis •

IMAGING General Features • Best diagnostic clue ○ Usually pancolitis, including rectum • Location ○ Dependent on etiology – C. difficile: Segmental or pancolitis □ Entire colon usually involved; distal SB uncommonly – Campylobacteriosis: Pancolitis ± small bowel – Escherichia coli (O157:H7): Pancolitis – Cytomegalovirus (CMV): Distal ileum and right colon or pancolitis – Yersinia enterocolitis: Predominantly right colon, occasionally left; invariably in terminal ileum □ RLQ clusters of enlarged nodes – Typhoid fever (salmonellosis): Cecum or right colon, invariably in ileum – Shigellosis: Predominantly in left colon – Tuberculosis: Right and proximal transverse colon, involves ileum – Actinomycosis: Rectosigmoid colon (intrauterine devices), ileocecal region (appendectomy) – Gonorrhea, chlamydia, herpes, syphilis: Rectosigmoid colon – Histoplasmosis: Ileocecal region – Mucormycosis: Right colon – Anisakiasis: Occasionally in right colon, rarely in transverse colon – Amebiasis: Right colon ± terminal ileum – Schistosomiasis: Left or sigmoid colon

Fluoroscopic Findings • Contrast enema ○ Used less frequently than before; now supplanted by CT, US, and endoscopy ○ Narrowed lumen, haustral thickening (edema/spasm) ○ Colonic wall, ulceration mucosal irregularity, superficial or deep "collar-button" ulcers ○ Discrete punctate, aphthous, or large oval ulcers, may simulate Crohn disease ○ Tuberculosis – Oval/circumferential transverse ulcers; loss of demarcation between distorted terminal ileum and ascending colon – Fleischner sign: Right-angle intersection between ileum and cecum, marked ileocecal valve hypertrophy – "Apple core" colonic stricture, indistinguishable from carcinoma

CT Findings • C. difficile, Campylobacter, E. coli, CMV ○ Mucosal hyperenhancement, marked submucosal edema, ascites

• •

• • •

○ Accordion sign: Alternating bands of enhancing mucosa and submucosal edema, with compressed lumen ○ Multiple air-fluid levels, infiltrated pericolonic fat ○ Deep ulcers and marked wall thickening – May progress to hemorrhagic necrosis and perforation – Toxic megacolon TB: Marked low-density enlargement of mesenteric lymph nodes ○ Enterocolitis is often due to ingestion of Mycobacterium bovis ○ Lungs may not be involved Histoplasmosis: Mesenteric adenopathy, hepatosplenomegaly ± calcifications Schistosomiasis: Changes in mesenteric or hemorrhoidal vein ○ ± calcification of bowel wall or liver ○ Bladder wall thickening and calcification Salmonellosis: May show small bowel thickening and effacement Actinomycosis: Large inflammatory masses Mucormycosis: Sinus, lung, and central nervous system changes

Colon

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformation

Ultrasonographic Findings • Wall thickening with increased symmetric thickening and submucosal echogenicity • Increased mural flow on color Doppler

DIFFERENTIAL DIAGNOSIS Ulcerative Colitis (UC) • Wall thickening is generally less prominent with UC vs. infectious colitis • Barium enema ○ Pancolitis with decreased haustration and multiple ulcerations ○ Mucosal "islands" or inflammatory pseudopolyps ○ Diffuse and symmetric thickening of colon wall ○ Chronic phase "lead pipe" colon

Granulomatous Colitis (Crohn Disease) • Concurrent SB (distal ileum) disease • Barium enema ○ Cobblestoning: Longitudinal and transverse ulcerations produce paving stone appearance ○ Transmural skip lesions, sinuses, fistulas

Ischemic Colitis • Usually located in watershed areas, rarely pancolitis • Rectum is rarely affected by ischemic colitis • CT: May show pneumatosis, portomesenteric venous gas, ± thrombus within splanchnic vessels

PATHOLOGY General Features • Etiology 459

Colon

Infectious Colitis ○ Most common bacterial causes of infectious colitis in USA – C. difficile, Salmonella, Campylobacter, and E. coli – Others: Mycobacterium tuberculosis, Actinomyces, Chlamydia trachomatis, Neisseria gonorrhoeae □ Chlamydia is causative agent for lymphogranuloma venereum ○ Most common viral agents of gastroenteritis: Norovirus and rotavirus ○ Most common protozoal: Cryptosporidium, Giardia, Cyclospora – In developing countries: Anisakis, Amoeba, Schistosoma, Strongyloides, Trichuris ○ Fungal organisms: Histoplasma, Mucor ○ Risk factors – C. difficile: Prior antibiotic use (especially clindamycin) □ Institutionalized patients (hospitals, nursing homes, prisons) □ Chemotherapy with colonic mucosal injury – CMV: Immunosuppression (e.g., transplant recipients) – Salmonella, Shigella: Outbreaks, warm weather – E. coli (0157:H7): Fecal contamination of meat (hamburger) or vegetables – Mycobacterium tuberculosis, CMV: Immunosuppression, including AIDS – Actinomyces: Intrauterine devices, appendectomy – Histoplasma, Mucor: Chronic debilitation or immunosuppression – Strongyloides: Severe debilitation ○ Pathogenesis – Ingestion of pathogenic organisms (often fecal-oral route) – Chlamydia, Neisseria gonorrhoeae, herpesvirus: Direct inoculation of rectum (anal intercourse)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ C. difficile colitis occurs mostly in institutionalized patients or those on antibiotics, chemotherapy, or immunosuppressants medication ○ Acute infectious diarrhea is most often a foodborne or waterborne disease – Symptoms: Fever, headache, nausea, vomiting, weight loss, anemia, malaise, rash – Watery or bloody diarrhea, painful abdominal cramps and tenderness – Arthritis, pneumonitis, seizures, peripheral neuropathy, microangiopathy • Laboratory data ○ Bacterial organisms: Increased neutrophilic count ○ Viral organisms: Increased lymphocytes (decreased in AIDS) ○ Fungal, parasitic organisms: Eosinophilia • Diagnosis: Stool cultures, blood cultures, endoscopic biopsy, serology studies

Demographics • Age ○ All ages, but incidence increases with age 460

○ Up to 1% of hospitalized patients develop C. difficile colitis • Epidemiology ○ Prevalence is grossly underestimated – Most patients do not seek medical attention – Testing for specific cause is frequently not done

Natural History & Prognosis • Complications ○ Hemorrhage, perforation, obstruction, toxic megacolon, bacteremia, sepsis, death ○ Yersinia enterocolitis: Hepatic abscess ○ Amebiasis: Liver and lung abscesses ○ Schistosomiasis: Hepatosplenomegaly portal hypertension • Prognosis ○ Usually very good with treatment – Often self-limited in previously healthy patients ○ Campylobacteriosis: 25% recurrence if untreated ○ E. coli (O157:H7) colitis: Higher morbidity and mortality – Hemolytic-uremic syndrome ○ CMV colitis: Hemorrhage and ischemia can be fatal – Often occurs in immunocompromised patients, adding to morbidity and mortality ○ Mucormycosis, strongyloidiasis: May be fatal

Treatment • Bacterial organisms: Mostly self-limiting, last 1-2 weeks, up to 1 month ○ C. difficile: Metronidazole; fecal transplantation to restore normal flora to colon ○ Salmonellosis: Parenteral cephalosporins if severe ○ Shigellosis: Ampicillin in severe cases ○ Yersinia enterocolitis: Lasts several months; no treatment available ○ E. coli (O157:H7) colitis: Supportive treatment, isolation procedures ○ TB: Antituberculosis drugs, no steroids • Viral organisms: Mostly self-limiting ○ CMV: Treat underlying AIDS • Parasitic organisms: Anthelmintic drugs ○ Anisakiasis: Mostly self-limiting, last 7-10 days • Fungal organisms: Antifungal drugs

DIAGNOSTIC CHECKLIST Consider • Diagnosis by clinical presentation,imaging, lab tests

SELECTED REFERENCES 1. 2. 3.

Aboutaleb N et al: Emerging infectious colitis. Curr Opin Gastroenterol. 30(1):106-15, 2014 Burke KE et al: Clostridium difficile infection: a worldwide disease. Gut Liver. 8(1):1-6, 2014 Raman SP et al: MDCT and CT angiography evaluation of rectal bleeding: the role of volume visualization. AJR Am J Roentgenol. 201(3):589-97, 2013

Infectious Colitis Colon

(Left) CT of a young man presenting with acute abdominal pain and diarrhea shows marked mural thickening and submucosal edema affecting both the ascending colon and distal ileum. A small amount of ascites is also seen. (Right) Another CT section in the same case shows more of the inflammation of the distal small bowel . The etiology was C. difficile infection, an unusual cause of small bowel inflammation.

(Left) A 61-year-old man was hospitalized for an orthopedic procedure and developed acute pain, diarrhea, and tachycardia. Axial CT shows a large amount of ascites . The splenic flexure shows mucosal hyperenhancement and submucosal edema . (Right) CT in the same case shows a loss of mucosal enhancement and transverse folds in some portions of the colon . These colonic segments seem to have a thin wall, while others are thick walled .

(Left) CT in the same case shows a fluid-distended rectosigmoid colon with loss of normal transverse folds. (Right) Coronal image in the same case shows gross dilation of the colon with some segments of wall thickening and others of thinning. Toxic megacolon due to C. difficile colitis was suggested on CT and confirmed on urgent total colectomy.

461

Colon

Infectious Colitis

(Left) A previously healthy young woman developed diarrhea and tenesmus. CT shows evidence of pancolitis with marked submucosal edema causing an "accordion" appearance of the colonic wall. (Right) CT in the same case shows involvement of the rectosigmoid colon but not the small bowel. Campylobacter colitis was the final diagnosis.

(Left) A young man with AIDS developed diarrhea and hematochezia. A supine radiograph shows massive thickening of the colonic folds with a "thumbprinted" appearance . (Right) CT in the same case shows anasarca, ascites, and dilation of the small bowel lumen. The wall of the entire colon is massively thickened. On endoscopy (not shown) the colonic mucosa was ischemic and biopsy showed cytomegalovirus (CMV) infiltrating the colonic wall and inducing hemorrhagic necrosis.

(Left) A young man developed RLQ pain, fever, and diarrhea. CT shows mural thickening of the ascending colon and RLQ lymphadenopathy . (Right) Another CT section in the same case shows wall thickening of the terminal ileum and additional enlarged nodes . This is a typical example of Yersinia enterocolitis with mesenteric adenitis. Most forms of infectious colitis spare the distal small bowel.

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Infectious Colitis Colon

(Left) A teenage girl developed acute bloody diarrhea due to E. coli colitis from contaminated hamburger. Coronal CT shows pancolitis with marked submucosal edema, and fluid distention of the entire colon . (Right) Another coronal CT section in this case shows more of the mucosal hyperenhancement and submucosal edema throughout the colon. The small bowel was spared.

(Left) CT of a 50-year-old woman with confirmed Salmonella colitis shows marked colonic fold thickening primarily affecting the ascending colon. Note that the presence of dense contrast material within the colon impairs evaluation for mucosal inflammation. (Right) CT in the same case shows marked submucosal edema in the cecum . The left side of the colon seems uninvolved. Preferential involvement of the right colon is characteristic of Salmonella (typhus), which is endemic in some populations.

(Left) An elderly woman developed acute diarrhea and tenesmus. CT shows pancolitis, with thickening of the wall and adjacent mesenteric hyperemia . The rectum and small bowel were spared. Campylobacter colitis was confirmed. (Right) Endoscopic image of the ascending colon in the same patient shows marked fold thickening due to Campylobacter colitis.

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Colon

Neutropenic Colitis (Typhlitis) KEY FACTS

TERMINOLOGY

PATHOLOGY

• Life-threatening, necrotizing enterocolitis occurring primarily in severely neutropenic patients

• Severely neutropenic patients • Majority of cases are those with leukemia &/or hematopoietic stem cell transplant recipients • Pathogenesis: Probably due to combination of factors ○ Mucosal injury by cytotoxic drugs ○ Profound immunosuppression ○ Invasion of bowel wall by microorganisms (polymicrobial) ○ Progressive necrosis of bowel wall

IMAGING • Best imaging tool: CECT with multiplanar reformations ○ Massive mural thickening of cecal ± ascending colon wall – Other segments of colon and small bowel can be affected ○ Mucosal hyperenhancement and submucosal edema (marked) ○ Infiltration of pericolonic fat • Less common, more severe findings ○ Pneumatosis, extraluminal gas and fluid (perforation)

TOP DIFFERENTIAL DIAGNOSES • Pseudomembranous colitis • Cecal diverticulitis • Crohn colitis

(Left) This 25-year-old woman was receiving chemotherapy for synovial sarcoma and became severely neutropenic, with complaints of abdominal pain, fever, and diarrhea. Axial CECT shows marked submucosal edema of the cecum and ascending colon . (Right) Another CT section in the same patient shows mucosal hyperenhancement and submucosal edema.

(Left) Coronal reformatted CT in the same patient shows inflammation of the ascending colon and terminal ileum , along with pericolonic ascites . (Right) Another coronal CT section in the same case shows pneumatosis within the cecal wall, which, along with ascites , suggested perforation, subsequently proven at surgery. Necrotizing, neutropenic colitis was the diagnosis.

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CLINICAL ISSUES • Fever, RLQ tenderness in immunosuppressed patient • Watery diarrhea, ± hematochezia

DIAGNOSTIC CHECKLIST • Consider history of chemotherapy for leukemia or bone marrow transplantation

Neutropenic Colitis (Typhlitis)

Synonyms • Neutropenic enterocolitis, ileocecal syndrome

Definitions • Life-threatening, necrotizing enterocolitis occurring primarily in severely neutropenic patients

IMAGING General Features • Best diagnostic clue ○ Massive mural thickening of cecal ± ascending colon wall • Location ○ Cecum, ascending colon ± distal ileum – Other segments of colon and small bowel can be affected

Gross Pathologic & Surgical Features

Radiographic Findings

• Hemorrhagic, thick, boggy cecum and ascending colon

• Radiography ○ "Thumbprinting" in wall of ascending colon, ± pneumatosis

Microscopic Features

Colon

○ Severely neutropenic patients (absolute neutrophil count < 500 cells/μL) – Majority of cases are those with leukemia &/or hematopoietic stem cell transplant recipients □ Especially those with acute myeloid leukemia – Myelodysplastic syndromes (lymphoma, aplastic anemia, myeloma) – Acquired immunodeficiency syndrome (AIDS) – Aggressive chemotherapy for solid malignancies ○ Pathophysiology – Mucosal injury by cytotoxic drugs – Profound immunosuppression – Invasion of bowel wall by microorganisms (bacterial and fungal) – Progressive necrosis of bowel wall – Probably due to combination of factors

TERMINOLOGY

• Inflammatory, ischemic, necrotic, ulcerative changes • Polymicrobial infection of bowel wall is often seen

CT Findings • CECT ○ Involvement of cecum, ascending colon ± distal ileum ○ Mucosal hyperenhancement ○ Submucosal edema (marked) ○ Infiltration of pericolonic fat ○ Less common, more severe findings – Pneumatosis in affected segments of bowel – Extraluminal gas or focal fluid (perforation)

Ultrasonographic Findings

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Fever, RLQ tenderness in immunosuppressed patient ○ Watery diarrhea, ± hematochezia ○ Abdominal distention, nausea, vomiting ○ Peritoneal signs and shock suggest perforation

Demographics

• Grayscale ultrasound ○ Hypoechoic or hyperechoic thickened bowel wall ○ Anechoic free fluid, ± mixed echoic abscess

• Age ○ Children > adults • Gender ○ M=F

Imaging Recommendations

Natural History & Prognosis

• Best imaging tool ○ CECT with multiplanar reformations

• Complications: Abscess, necrosis, perforation, sepsis • Prognosis: Early stage (good), late stage (poor) ○ Mortality has decreased to < 10% in recent series due to earlier diagnosis and better medical and surgical intervention

DIFFERENTIAL DIAGNOSIS Infectious Colitis • Due to Clostridium difficile or other organisms, usually pancolitis • Patients are usually not so severely neutropenic

Treatment

Cecal Diverticulitis

• Medical: High doses of antibiotics and IV fluids • Complicated case: Granulocyte transfusions; surgical resection for perforation

• Bowel wall thickening, fat stranding, free fluid/air, cecal outpouching • Mucosal hyperenhancement usually absent

Consider

Crohn colitis • Usually affects small bowel ± other colonic segments in addition

DIAGNOSTIC CHECKLIST • History of chemotherapy for leukemia or bone marrow transplantation

SELECTED REFERENCES

PATHOLOGY

1.

General Features

2.

del Campo L et al: Abdominal complications following hematopoietic stem cell transplantation. Radiographics. 34(2):396-412, 2014 Talebian Yazdi A et al: Neutropenic colitis. JBR-BTR. 94(3):138-9, 2011

• Etiology 465

Colon

Ulcerative Colitis KEY FACTS

TERMINOLOGY • Chronic, idiopathic, diffuse, inflammatory disease primarily involving colorectal mucosa

• Ischemic colitis ○ Rectum is almost always spared in ischemic colitis • Cathartic colon

IMAGING

PATHOLOGY

• Distal or pancolitis with mucosal hyperenhancement and only moderate submucosal edema • Rectum only (30%), rectum and distal colon colon (40%), pancolitis (30%) ○ Terminal ileum affected in minority of patients • Toxic megacolon ○ Colon is dilated with loss of fold and mucosal pattern ○ Ascites is common ± pneumatosis, pneumoperitoneum

• Associated pathology ○ Greater risk of colorectal cancer in UC than Crohn colitis ○ Primary sclerosing cholangitis, uveitis ○ Ankylosing spondylitis, rheumatoid arthritis

TOP DIFFERENTIAL DIAGNOSES • Granulomatous colitis (Crohn disease) • Infectious (including Clostridium difficile) colitis ○ Degree of mucosal enhancement and submucosal edema is usually greater than seen in ulcerative colitis

(Left) Graphic illustration demonstrates innumerable "collar button" ulcers and a loss of haustra throughout the descending and sigmoid colon. (Right) Single-contrast barium enema shows innumerable "collar button" ulcers and loss of haustra throughout the descending colon.

(Left) This 51-year-old woman has an acute flare of chronic ulcerative colitis. Coronal CECT shows pancolitis with mucosal hyperenhancement and submucosal edema , with blunted transverse folds . (Right) Axial CT in the same patient shows the mucosal hyperenhancement and submucosal edema . Note the prominent vessels supplying the inflamed colon.

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DIAGNOSTIC CHECKLIST • Consider UC in any patient with sclerosing cholangitis • Consider other causes of colitis, especially infectious and Crohn disease

Ulcerative Colitis

Abbreviations • Ulcerative colitis (UC)

Definitions • Chronic, idiopathic, diffuse, inflammatory disease primarily involving colorectal mucosa

IMAGING General Features • Best diagnostic clue ○ Distal or pancolitis with mucosal hyperenhancement and only moderate submucosal edema • Location ○ Rectum only (30%), rectum and distal colon colon (40%), pancolitis (30%) – Terminal ileum affected in minority of patients • Morphology ○ Moderate wall thickening and luminal narrowing in acute phase ○ Foreshortened and ahaustral colon in chronic phase – Described as "lead pipe" or "windowpane"

Fluoroscopic Findings • Barium enema ○ Acute – Colorectal narrowing, incomplete filling (spasm + irritability) – Fine mucosal granular pattern (edema/hyperemia) – Mucosal stippling: Punctate barium collections and ulcers due to mucosal erosion and crypt abscesses – Flask-shaped "collar button" ulcers □ Ulcers may progress to widespread mucosal sloughing □ Residual or hyperplastic mucosa may appear as pseudopolyps – Thickened transverse folds due to submucosal edema ○ Chronic – Shortened, less redundant colon – "Lead pipe" or "windowpane" colon – Blunted or complete loss of transverse folds – Luminal narrowing and widened presacral space > 1.5 cm – Benign or malignant strictures

CT Findings • CECT ○ Target or halo sign – Enhancing inner ring of bowel wall (mucosa) – Nonenhancing middle ring of bowel wall (submucosa) – Enhancing outer ring of bowel wall (muscularis propria and serosa) ○ Enhancement of mucosal islands or inflammatory pseudopolyps ○ Wall thickening generally < 10 mm ○ Perirectal fibrofatty proliferation and narrowing of rectal lumen – Results in widening of presacral (retrorectal) space ○ Toxic megacolon

– Colon is dilated, often > 8 cm (on CT, more on plain films) □ Small bowel also dilated (ileus) – Colonic wall may be thick or thin – Loss of normal transverse folds and mucosal pattern □ Mucosal islands or pseudopolyps may be seen – Ascites is common ± pneumatosis, pneumoperitoneum

Colon

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformations ○ Air-contrast barium enema provides excellent depiction of colonic mucosal disease – Rarely requested or performed in era of easy access to CT and colonoscopy

DIFFERENTIAL DIAGNOSIS Granulomatous Colitis (Crohn Disease) • Granulomatous colitis (GC) is transmural inflammation while UC is generally more limited to mucosa • More often has skip lesions and involvement of small bowel • Barium enema ○ Aphthous ulcers: Shallow collection of barium in mucosal ulceration with surrounding edema ○ "Cobblestoning": Longitudinal and transverse ulcerations with paving stone appearance ○ Segmental distribution: Colon and small bowel (60% of cases); isolated to colon (20% of cases) ○ Transmural, skip lesions, sinuses, fissures, fistulas ○ Minority of cases may be indistinguishable from UC, especially in late phase • CT ○ Bowel wall thickening (10-20 mm) is greater with GC than with UC ○ Inflammation of adjacent mesenteric fat results in fibrofatty proliferation (creeping fat) especially in RLQ ○ Comb sign: Mesenteric hypervascularity indicates active disease ○ Enlarged mesenteric lymph nodes

Infectious (Including Clostridium difficile) Colitis • Usually involves entire colon • Degree of mucosal enhancement and submucosal edema is usually greater than seen in UC • Accordion sign: Contrast trapped between thickened colonic folds • Ascites common in infectious colitis, rare in UC (except in severe cases, such as with toxic megacolon)

Ischemic Colitis • Hypoperfusion is most common etiology ○ Usually seen in watershed areas: Splenic flexure, sigmoid colon, descending colon ○ Rectum is almost always spared in ischemic colitis ○ More common in elderly and "cardiac" patients • CECT ○ Mucosal enhancement is usually normal or increased (after initial insult) ○ ± pneumatosis, portomesenteric venous gas 467

Colon

Ulcerative Colitis

Cathartic Colon

Demographics

• Long-term use/abuse of laxatives and cathartics • Ahaustral colon resembles chronic UC • Irregular and transient segmental narrowing, primarily in ascending and transverse colon

• Age ○ Initial onset: 15-40 years (small peak at 55-65 years) • Gender ○ M = F overall, with female onset of disease generally earlier than in men • Ethnicity ○ More common in Caucasians and Jews • Epidemiology ○ 30-100x greater incidence in 1st degree relatives than general population ○ But only 10-25% of persons with UC have 1st degree relative with the disease

Neutropenic Colitis • In severely neutropenic, immunocompromised patients • Usually limited to right colon and cecum • Mucosal and mesenteric hyperemia with marked submucosal edema

Diverticulitis • Most common in sigmoid colon, spares rectum • Does not result in mucosal hyperemia • Bowel wall and fascial thickening, fat stranding, free fluid or gas • Pericolic inflammatory changes: Abscess, sinuses, fistulas • Rare in patients with UC

PATHOLOGY General Features • Etiology ○ Many etiological factors have been cited – Genetic, familial, environmental, neural, and hormonal – Infectious, nutritional, immunological, vascular – Traumatic, psychological, and stress factors • Genetics ○ Increased incidence in monozygotic twins ○ However, > 75% of patients with UC have no family history of this disease ○ HLA B5, BW52, and DR2 genes have been linked to UC • Associated abnormalities ○ Primary sclerosing cholangitis, uveitis ○ Ankylosing spondylitis, rheumatoid arthritis ○ Pyoderma gangrenosum, sacroiliitis ○ Greater risk of colorectal cancer in UC than Crohn colitis – Annual incidence: 10% after 1st decade of UC – UC pancolitis in 75-80% of colon cancer patients – Multiple carcinomas in 25% of UC cases • Incidence ○ Range from 2-20 per 100,000 person years In North America

Natural History & Prognosis • Begins in rectum with proximal extension to part or all of colon • Backwash ileitis: Inflamed distal ileum in 10-40% of chronic UC patients • Complications ○ Toxic megacolon, colorectal cancer, strictures ○ Increased incidence of colon carcinoma (up to 50%) after 25 years of disease • Diagnosis: Mucosal biopsy and histology • Prognosis ○ Improves with diagnosis and management

Treatment • Medical ○ Sulfasalazine, steroids, azathioprine ○ Methotrexate, LTB4 inhibitors • Surgical: Total or proctocolectomy, Brooke or continent ileostomy ○ Ileal pouch with ileoanal anastomosis

DIAGNOSTIC CHECKLIST Consider • Consider UC in any patient with sclerosing cholangitis • Rule out other inflammatory diseases of colon

Image Interpretation Pearls • Colorectal narrowing, punctate and "collar button" ulcers • Continuous concentric and symmetric involvement • "Lead pipe" colon and loss of transverse folds

Gross Pathologic & Surgical Features • Continuous concentric and symmetric colonic involvement; pseudopolyps

SELECTED REFERENCES 1.

Microscopic Features • Inflammatory infiltrate, crypt microabscesses • Limited to mucosa and submucosa

2.

3.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Relapsing bloody mucous diarrhea ○ Fever, weight loss, abdominal pain and cramps • Other signs/symptoms ○ Lab data: Blood and mucus in stool 468

4.

5.

Marineaţă A et al: Extra intestinal manifestations and complications in inflammatory bowel disease. Rev Med Chir Soc Med Nat Iasi. 118(2):279-88, 2014 Patel NS et al: Outcomes of computed tomography and magnetic resonance enterography in clinical practice of inflammatory bowel disease. Dig Dis Sci. 59(4):838-49, 2014 Reich KM et al: The incidence rate of colectomy for medically refractory ulcerative colitis has declined in parallel with increasing anti-TNF use: a timetrend study. Aliment Pharmacol Ther. 40(6):629-38, 2014 Hammer MR et al: Multidetector computed tomographic and magnetic resonance enterography in children: state of the art. Radiol Clin North Am. 51(4):615-36, 2013 Hristova L et al: Colorectal cancer in inflammatory bowel diseases: CT features with pathological correlation. Abdom Imaging. 38(3):421-35, 2013

Ulcerative Colitis Colon

(Left) Axial CECT in a woman with ulcerative colitis and primary sclerosing cholangitis shows diffuse colon fibrosis and loss of transverse folds (lead pipe appearance). Homogeneous low attenuation of the thickened colon wall denotes longstanding disease. (Right) Axial CECT in the same patient shows mural thickening of the distal terminal ileum, known as backwash ileitis . Primary sclerosing cholangitis is strongly associated with ulcerative colitis.

(Left) Supine film in a 55-yearold woman with longstanding UC and abdominal pain shows the relatively straight and ahaustral colon with superimposed "thumbprinting" . (Right) Axial CT in the same patient shows mild diffuse colonic wall thickening without significant hyperenhancement of the mucosa , nor submucosal edema, typical findings of longstanding UC with fibrosis. Colonoscopy proved this patient to have active inflammation only of the sigmoid colon (not shown).

(Left) CT in a 49-year-old man with weight loss and anemia with chronic intermittent mucous diarrhea shows a circumferential soft tissue density mass that narrows the lumen of the ascending colon. The mass proved to be a primary carcinoma. (Right) CT in the same patient shows signs of pancolitis, with mucosal hyperenhancement and submucosal edema . Longstanding UC predisposes to colon cancer.

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Colon

Toxic Megacolon KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Acute transmural fulminant colitis with neuromuscular degeneration and colonic dilatation

• Most severe, life-threatening complication of colitis • Most common signs/symptoms ○ Patients appear "toxic," very ill ○ Fever, pain, abdominal distension, bloody diarrhea ○ Complications: Perforation, peritonitis, death • Other signs/symptoms ○ Lab data: Increased WBC and ESR; positive fecal occult blood test • Treatment: Colectomy and treatment of complications • Prognosis: Good following colectomy without perforation ○ Poor if colonic perforation and sepsis precede colectomy • Seen in ~ 5% of infectious or ulcerative colitis patients

IMAGING • Best diagnostic clue: Dilated colon with air-fluid levels and abnormal mucosal and transverse fold patterns ○ Transverse colonic folds may be thickened (edema or hemorrhage), or lost (sloughed mucosa and submucosa)

TOP DIFFERENTIAL DIAGNOSES • Colonic obstruction or Ileus ○ Preservation of mucosal and transverse fold pattern

PATHOLOGY • Clostridium difficile and other infectious colitis ○ Now the most common etiology ○ Ulcerative colitis was more common in past

(Left) Supine radiograph in a 58-year-old woman, who presented with severe abdominal pain and bloody diarrhea, illustrates the typical appearance of toxic megacolon on plain film. The transverse colon is dilated with marked thickening of the transverse folds . (Right) This 35-year-old man with a history of ulcerative colitis presents with acute severe abdominal pain and distention. This supine radiograph shows a dilated, ahaustral transverse colon with a "shaggy" surface contour.

(Left) This woman developed Clostridium difficile colitis while hospitalized for other reasons. CT shows ascites , marked dilation of the colon with loss of transverse folds, and intraluminal high-density material representing hemorrhage and sloughed mucosa. (Right) Axial CECT in the same case shows a generalized ileus . The colon is massively distended with blood and debris and its wall is relatively thin. Soon after this scan, the colon perforated and a total colectomy was required.

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DIAGNOSTIC CHECKLIST • Consider prior history of infectious or ulcerative colitis • Dilated colon with air-fluid levels; thickened or absent transverse folds in a very sick patient

Toxic Megacolon

Definitions • Acute transmural fulminant colitis with neuromuscular degeneration and colonic dilation

IMAGING

Gross Pathologic & Surgical Features • Colon is grossly dilated with fluid and gas • Wall may appear thinned or thick • Hemorrhagic necrosis of colonic mucosa and submucosa ○ May extend into or through serosa

CLINICAL ISSUES

General Features

Presentation

• Best diagnostic clue ○ Dilated ahaustral colon with pseudopolyps and air-fluid levels

• Most common signs/symptoms ○ Patients appear "toxic," very ill ○ Fever, pain, tenderness, abdominal distension, bloody diarrhea ○ Hypotension, sepsis, shock • Other signs/symptoms ○ Lab data: Increased WBC and ESR

Radiographic Findings • Radiography ○ Hallmark: Marked colonic dilatation with abnormal or absent fold pattern – Transverse colon most common ± other segments – Increased colon caliber on serial radiographs □ > 5 cm on CT, often > 8 cm (as measured on supine radiograph) – Transverse colonic folds may be thickened (edema or hemorrhage), or lost (sloughed mucosa and submucosa) – Mucosal islands or pseudopolyps cause irregular surface contour – Pneumatosis coli ± pneumoperitoneum

CT Findings • Colon distended with gas, fluid ± blood • Distorted or absent transverse fold pattern • Irregular nodular contour of colonic wall (mucosal pseudopolyps) • ± intramural gas ± blood • ± free intraperitoneal gas and fluid

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformations

DIFFERENTIAL DIAGNOSIS Colonic Obstruction • Gas- and stool-filled colon to point of obstruction • Retained transverse fold and mucosal patterns excludes toxic megacolon

Demographics • Age ○ Any age for infectious colitis patients – 20-35 years for ulcerative colitis patients • Gender ○ M=F • Epidemiology ○ Seen in ~ 5% of patients with infectious or ulcerative colitis – Medical and surgical mortality: > 20% – Most severe, life-threatening complication of colitis

Natural History & Prognosis • For infectious colitis ○ Delayed diagnosis or failed antibiotic therapy may result in toxic megacolon • For ulcerative colitis, predisposing factors ○ Endoscopy; use of opiates and anticholinergic drugs • Complications: Perforation, peritonitis, death • Prognosis: Good following colectomy without perforation ○ Poor if colonic perforation and sepsis precede colectomy

Treatment • Colectomy; treat complications

DIAGNOSTIC CHECKLIST Consider

Adynamic or Paralytic Ileus

• Prior history of infectious or ulcerative colitis

• Dilated small and large bowel without transition point • Normal transverse fold pattern excludes toxic megacolon

Image Interpretation Pearls

PATHOLOGY General Features • Etiology ○ Clostridium difficile and other infectious colitis – Now the most common etiology – Ulcerative (and granulomatous) colitis had been more common in past ○ Amebiasis, strongyloidiasis, bacillary dysentery ○ Typhoid fever, cholera, Behçet syndrome

Colon

TERMINOLOGY

• Dilated colon with air-fluid levels; thickened or absent transverse folds in a very sick patient

SELECTED REFERENCES 1. 2.

3. 4.

Jethwa KD et al: The importance of the abdominal X-radiograph in acute ulcerative colitis. Arch Dis Child Educ Pract Ed. 99(5):188, 200, 2014 Kazanowski M et al: Clostridium difficile: epidemiology, diagnostic and therapeutic possibilities-a systematic review. Tech Coloproctol. 18(3):223-32, 2014 Miniello S et al: Toxic megacolon in ulcerative rectocolitis. Current trends in clinical evaluation, diagnosis and treatment. Ann Ital Chir. 85(1):45-9, 2014 Narabayashi K et al: Oral tacrolimus for megacolon in patients with severe ulcerative colitis. Intern Med. 53(16):1755-8, 2014

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Toxic Megacolon

(Left) This 68-year-old woman has longstanding Crohn (granulomatous) colitis with acute exacerbation. This supine film shows marked dilation of the transverse colon with a featureless ahaustral appearance. There is some irregularity of the luminal surface , suggesting mucosal sloughing or pseudopolyps. (Right) Axial CECT in the same patient shows the colonic dilation and ahaustral appearance with marked thinning of the wall, which suggests a risk of perforation.

(Left) A magnified view of the same CT section shows tags of inflamed mucosa or pseudopolyps within the dilated, thin-walled transverse colon. (Right) Another CT section in the same patient shows fluid , distention and thinning of the walls of the colon, as well as more mucosal pseudopolyps .

(Left) Axial CECT in the same patient shows similar involvement of the rectosigmoid colon . Because of symptoms that were refractory to medical management, as well as these CT findings, the patient had a total colectomy. (Right) Gross pathology photograph from a similar patient who underwent colectomy illustrates hemorrhagic necrosis of the colonic mucosa and pseudopolyps in a case of toxic megacolon.

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Toxic Megacolon Colon

(Left) This 61-year-old man was hospitalized for unrelated reasons and developed acute pain, diarrhea, hypotension, and tachycardia. This supine film shows bulging flanks due to ascites. The colon is diffusely dilated with a loss of the normal transverse fold pattern. The folds that are seen are grossly thickened and have a "thumbprint" appearance . (Right) Axial CECT in the same patient shows ascites and colonic distension .

(Left) Another CT section in the same patient shows that the colon is distended with gas and fluid to a diameter of 7 cm. The mucosa is hyperenhancing and the wall is thickened by submucosal edema . No normal transverse folds are evident. Ascites fills the paracolic gutters , accounting for the bulging flanks seen on plain films. (Right) Pelvic CT section in the same patient shows marked fluid distention and wall thickening of the rectosigmoid colon .

(Left) Coronal reformatted CT section in the same patient shows the markedly distended sigmoid colon with a complete loss of its normal transverse fold pattern. (Right) Another CT section in the same patient confirms the pancolitis and ascites . These CT and clinical features are classic for toxic megacolon due to infectious colitis (C. difficile), confirmed at urgent colectomy. The colonic mucosa showed extensive necrosis and sloughing, but no frank perforation was found.

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Colon

Ischemic Colitis KEY FACTS

TERMINOLOGY • Compromise of mesenteric blood supply leading to colonic injury

IMAGING • Best imaging tool: CECT with multiplanar reformations without enteric contrast medium • Best diagnostic clue: Segmental colonic wall thickening in "watershed" distribution, ± pneumatosis and portal venous gas • Findings vary by acuity, etiology, and severity • Acute arterial thromboembolic ○ Emboli to SMA from cardiac sources most commonly ○ Affects right colon ± small bowel ○ CT findings often subtle (ileus, lack of mucosal enhancement, no wall thickening acutely) • Mesenteric venous thrombosis ○ Thrombosis or filling defect in SMV

(Left) Graphic shows luminal narrowing and wall thickening near the splenic flexure, a "watershed" area between the vascular distribution of the SMA and IMA. (Right) This 89year-old man had pain and bloody diarrhea several hours after a hip arthroplasty procedure. Coronal reformatted CECT shows wall thickening and mucosal and mesenteric hyperemia affecting the descending colon . Incidental renal allograft noted .

(Left) Axial CECT in the same case shows submucosal edema and luminal narrowing of the descending colon . The SMA and SMV are patent. (Right) Another CT section in this patient shows wall thickening and pericolonic stranding of the descending colon , whereas the remaining colon is normal. The rectum (not shown) was normal. These are classic clinical and CT features of ischemic colitis due to a hypotensive episode in an elderly patient.

474

○ Marked submucosal edema of affected colon (right > left) ± small bowel ○ Marked infiltration of mesentery ± ascites • Hypoperfusion ischemia ○ Elderly, cardiac patients; recent hypotensive episode ○ Affects "watershed" areas of colon (splenic flexure and descending colon > sigmoid) ○ Rectum is rarely affected by ischemic colitis

TOP DIFFERENTIAL DIAGNOSES • Diverticulitis • Infectious (including Clostridium difficile) colitis • Granulomatous colitis (Crohn disease)

PATHOLOGY • Hypoperfusion: Predisposing factors ○ Hypotensive episodes: Hemorrhagic, cardiogenic, or septic shock ○ CHF, arrhythmia, drugs (e.g., digitalis), trauma

Ischemic Colitis

Definitions • Compromise of mesenteric blood supply leading to colonic injury

IMAGING General Features • Best diagnostic clue ○ Symmetric, long segmental colonic wall thickening on CT ○ Pneumatosis, mesenteric venous gas; more definitive but less common findings

Radiographic Findings • Radiography ○ Supine abdominal films – Normal or nonspecific ileus – "Thumbprinting" (submucosal edema or hemorrhage) – Luminal narrowing or transverse ridging (spasm)

Fluoroscopic Findings • Barium enema ○ Hallmark: Serial change on studies performed over days, weeks, or months ○ "Thumbprinting" – Usually within 24 hours after onset – Thickened, nodular transverse folds (submucosal edema or hemorrhage) – Most consistent and characteristic finding (75% of cases) ○ Ulceration: Mucosal sloughing – Usually 1-3 weeks after onset – Longitudinal or discrete, superficial or deep, small or large collections of barium ○ Stricture: 12% of cases heal with stricture formation ○ Intramural barium: Rare, due to sloughing of necrotic mucosa

Ultrasonographic Findings • Color Doppler ○ Hypoechoic bowel wall thickening ○ Absent arterial flow in colon wall

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformations – Mucosal enhancement & submucosal edema are better seen without use of enteric contrast media

DIFFERENTIAL DIAGNOSIS

CT Findings • NECT ○ Circumferential, symmetric wall thickening ± "thumbprinting" – Hypoattenuation of bowel wall: Submucosal or diffuse edema – Hyperattenuation of bowel wall: Submucosal hemorrhage ○ Luminal narrowing or dilatation, and air-fluid levels ○ Pneumatosis: intramural gas in circumferential or bandlike collections ○ Gas in mesenteric and portal veins – Tends to collect in periphery of liver (unlike biliary gas) • CECT ○ Findings vary by acuity, etiology, and severity ○ Acute arterial thromboembolic – Emboli to SMA from cardiac sources most commonly □ e.g., prosthetic cardiac valves, prior myocardial infarction, atrial fibrillation □ Symptoms are more likely to be acute and severe – Occlusion or filling defect in lumen of superior mesenteric artery (SMA) – Affects right side of colon ± small bowel

Colon

– CT findings often subtle (ileus, lack of mucosal enhancement) □ No bowel wall edema or mesenteric infiltration until reperfusion occurs □ Pneumatosis ± portal venous gas: Late findings of frank infarction ○ Mesenteric venous thrombosis – Often in hypercoagulable patients – Thrombosis or filling defect in SMV – Results in marked submucosal edema of affected colon (right > left) ± small bowel – Marked infiltration of mesentery ± ascites – Mucosal enhancement is often normal or increased – Onset of symptoms more likely to be subacute and less severe ○ Hypoperfusion ischemia – Usually in elderly, cardiac patients; those with recent hypotensive episode – Affects "watershed" areas of colon □ Splenic flexure: Junction of SMA and inferior mesenteric artery (IMA) (Griffith point) □ Left colon: Typical in elderly with decreased perfusion □ Sigmoid colon: Junction of IMA and hypogastric artery (Sudeck point) – Rectum is rarely affected by ischemic colitis

TERMINOLOGY

Diverticulitis • • • •

Long segment (usually sigmoid) involvement Diverticula and soft tissue density wall thickening Pericolonic infiltration ± extraluminal gas and fluid Sigmoid mesocolic vascular engorgement

Infectious (Including Clostridium difficile) Colitis • • • •

Usually pancolitis including rectum CECT: Marked submucosal edema (accordion sign) Mucosal hyperenhancement Ascites is common

Ulcerative Colitis • Acute ○ Distal rectosigmoid > pancolonic ○ ± "backwash ileitis" ○ Mucosal and mesenteric hyperemia ○ Not as much colonic wall thickening as with infectious colitis • Chronic ○ Colonic foreshortening and loss of transverse folds – "Windowpane" or "lead pipe" appearance 475

Colon

Ischemic Colitis ○ Mucosal sloughing evolving into pseudopolyps

Granulomatous Colitis (Crohn Disease) • Acute ○ Favors distal small bowel ± colon ○ Mucosal and mesenteric hyperemia ○ Submucosal edema, luminal narrowing ○ Mesenteric adenopathy • Chronic ○ Luminal strictures ○ Mesenteric fibrofatty proliferation

Colon Carcinoma • Soft tissue density, short segment, wall thickening • Luminal narrowing or obstruction (especially for distal colonic tumors) ○ Bulky, nonobstructing masses in ascending colon • Adjacent lymphadenopathy ± transmural tumor extension • Liver metastases

PATHOLOGY

Natural History & Prognosis • Complications ○ Reversible or transient ischemic is common ○ Colonic stricture, gangrene of colon, perforation ○ Transmural bowel infarction may cause perforation or even death • Prognosis ○ Transient, mucosal ischemia: Good ○ Transmural infarction: Poor

Treatment • Partial mural ischemia (nonocclusive) ○ Conservative medical treatment; fluid resuscitation • Transmural infarction ○ Surgical resection of ischemic colon

DIAGNOSTIC CHECKLIST

General Features

Consider

• Etiology ○ Most common vascular disorder of GI tract ○ 90% of cases are segmental or pancolitis ○ Hypoperfusion: Predisposing factors – Hypotensive episodes □ Hemorrhagic, cardiogenic, or septic shock □ CHF, arrhythmia, drugs (e.g., digitalis), trauma – Arteriosclerotic disease, chronic renal failure – Upstream of colonic obstruction □ Cancer or volvulus

• Consider history of cardiac, bowel, renal problems and hypotensive medication use in elderly

Gross Pathologic & Surgical Features

3.

• Segmental or focal; localized or diffuse • Thickened bowel wall; dark red or purple discoloration ○ Hemorrhagic, ulcerated mucosa

Image Interpretation Pearls • Segmental bowel wall thickening in watershed areas • "Thumbprinting," pneumatosis, portal venous gas

SELECTED REFERENCES 1. 2.

4. 5.

Microscopic Features

6.

• Mucosal erosions, ulcerations, necrosis; submucosal edema, hemorrhage

7.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Mild to severe abdominal pain ○ Rectal bleeding, bloody diarrhea, hypotension • Lab data ○ leukocytosis, positive guaiac stool test ○ Negative blood cultures; EKG changes may be seen

Demographics • Age ○ Usually elderly – > 60 years old • Gender ○ M=F • Epidemiology ○ Major predisposing cause in elderly: Nonocclusive vascular disease (hypoperfusion) 476

– Most common cause of colitis in elderly, often selflimiting □ Mortality rate estimated at 7%

8. 9. 10.

11. 12. 13. 14.

Sise MJ: Acute mesenteric ischemia. Surg Clin North Am. 94(1):165-81, 2014 Raman SP et al: MDCT and CT angiography evaluation of rectal bleeding: the role of volume visualization. AJR Am J Roentgenol. 201(3):589-97, 2013 Tadros M et al: A review of ischemic colitis: is our clinical recognition and management adequate? Expert Rev Gastroenterol Hepatol. 7(7):605-13, 2013 O'Neill S et al: Systematic review of the management of ischaemic colitis. Colorectal Dis. 14(11):e751-63, 2012 Green BT et al: Ischemic colitis: a clinical review. South Med J. 98(2):217-22, 2005 Korotinski S et al: Chronic ischaemic bowel diseases in the aged--go with the flow. Age Ageing. 34(1):10-6, 2005 Ripolles T et al: Sonographic findings in ischemic colitis in 58 patients. AJR Am J Roentgenol. 184(3):777-85, 2005 Sreenarasimhaiah J: Diagnosis and management of ischemic colitis. Curr Gastroenterol Rep. 7(5):421-6, 2005 Wiesner W et al: CT of acute bowel ischemia. Radiology. 226(3):635-50, 2003 Horton KM et al: Volume-rendered 3D CT of the mesenteric vasculature: normal anatomy, anatomic variants, and pathologic conditions. Radiographics. 22(1):161-72, 2002 Horton KM et al: Multi-detector row CT of mesenteric ischemia: can it be done? Radiographics. 21(6):1463-73, 2001 Horton KM et al: CT evaluation of the colon: inflammatory disease. Radiographics. 20(2):399-418, 2000 Balthazar EJ et al: Ischemic colitis: CT evaluation of 54 cases. Radiology. 211(2):381-8, 1999 Iida M et al: Ischemic colitis: serial changes in double-contrast barium enema examination. Radiology. 159(2):337-41, 1986

Ischemic Colitis Colon

(Left) This 69-year-old woman has aortic stenosis and was receiving medication for hypertension. She had sudden onset of abdominal pain and hematochezia. CT shows wall thickening in the proximal descending colon , whereas the more proximal colon is gas-distended with a normal wall. (Right) Axial CECT section in this case shows massive wall thickening ("thumbprinting") of the sigmoid colon . The rectum is spared. Ascites is noted. These are classic clinical and CT features of ischemic colitis.

(Left) This elderly patient has severe atherosclerosis and presents with abdominal pain and hypotension. NECT shows gas within the wall of the ascending colon , which is otherwise relatively normal in appearance. (Right) Coronal NECT in the same patient shows gas within the wall of the distal small bowel as well as the ascending colon. Portal venous gas is also present. These are typical features of thromboembolic occlusion of the SMA.

(Left) This man had abdominal pain and hematochezia following resuscitation for cardiac arrest during dialysis. CT shows mural thickening with submucosal edema throughout the ascending and transverse colon (not shown). (Right) Coronal CT in the same patient shows mural thickening and edema of the small bowel , whereas the distal colonic wall is normal. This distribution of ischemic injury likely resulted from a combination of atherosclerotic narrowing of the SMA and the hypotensive episode.

477

Colon

Appendicitis KEY FACTS

TERMINOLOGY • Acute appendiceal inflammation due to luminal obstruction and superimposed infection

IMAGING • US: Distended, thick-walled, noncompressible appendix ( 7 mm) ○ Sonographic McBurney sign with focal pain over appendix ○ Shadowing, echogenic appendicolith ○ Increased flow within wall of appendix, indicating inflammation ○ Increased echogenicity of inflamed periappendiceal fat • CT: Abnormal mural enhancement of distended appendix ○ Thin sections (1.25-2.5 mm), viewed in axial, coronal ± sagittal planes ○ Inflamed mucosa may show hyperenhancement ○ Necrotic wall may show no enhancement ○ Periappendiceal fat stranding

(Left) This graphic illustrates some of the characteristic features of acute appendicitis, including the distended, thickwalled, inflamed appendix and inflammatory thickening of the adjacent walls of the cecum and terminal ileum . (Right) Axial CECT in 12-yearold boy shows perforated appendicitis. Note the appendicolith and cecal wall thickening . The focally necrotic wall of the appendix delineates the point of perforation. Pericecal and periappendiceal inflammatory changes are also evident.

(Left) Longitudinal sonogram demonstrates a distended, thick-walled appendix , 10 mm in diameter with adjacent hyperechoic periappendiceal inflammation of fat , indicative of an inflammatory process and diagnostic for appendicitis. (Right) Color power Doppler sonography in a patient with acute appendicitis demonstrates marked hyperemia in the wall of the appendix , indicative of inflammation and consistent with acute appendicitis.

478

○ Appendicolith may be present (15-40%) ○ ± periappendiceal abscess or phlegmon • MR is a good alternative to CT in pregnant patients, and children when US is nondiagnostic

TOP DIFFERENTIAL DIAGNOSES • • • • • • • •

Mesenteric adenitis and enteritis Ileocolitis Crohn disease Gynecologic causes Cecal diverticulitis Appendiceal tumor Cecal carcinoma Cystic fibrosis

CLINICAL ISSUES • Clinical diagnosis is incorrect in ~ 20% of young men and 40% of young women • Also frequently in error in young children and older adults

Appendicitis

Definitions • Acute appendiceal inflammation due to luminal obstruction and superimposed infection

IMAGING General Features • Best diagnostic clue ○ Distended, thick-walled, noncompressible appendix ( 7 mm) on US ○ Abnormal mural enhancement of distended appendix on CECT ○ Periappendiceal fat stranding on US or CT • Location ○ Appendix arises from cecal tip, but tip may lie some distance from cecum • Size ○ Noncompressible appendix on US – > 6 mm has sensitivity of 100%, but specificity of only 64% – > 7 mm has sensitivity of 94% and specificity of 88% – 6-7 mm equivocal size; increased flow on color Doppler in appendix indicates positive study • Morphology ○ Tip of appendix often 1st site of inflammation and appendiceal perforation

Radiographic Findings • Radiography ○ Appendicolith in < 5% of patients (on plain films) ○ Air-fluid levels within bowel in RLQ – Due to focal ileus ○ With perforation – Small bowel obstruction (SBO)

CT Findings • NECT ○ Dilated appendix 7 mm ○ Periappendiceal fat stranding ○ Appendicolith – Seen much more frequently on CT than on radiography – Even noncalcified appendicoliths may be seen on CT ○ With perforation – Small bowel obstruction • CECT ○ Dilated appendix 7 mm – Sensitivity 95%, specificity 95% ○ Abnormal enhancement of appendiceal wall on CECT – Inflamed mucosa may show hyperenhancement – Necrotic wall may show no enhancement – Wall may be discontinuous at point of perforation □ ± bubbles of extraluminal gas ○ Appendicolith may be present (15-40%) ○ Focal bowel wall thickening of adjacent wall of cecum &/or terminal ileum – Focal ileus of distal small bowel due to inflammation and spasm of lumen

– Frank SB obstruction may occur with abscess or delayed diagnosis ○ RLQ extraluminal inflammation – Diffuse nonencapsulated inflammation of mesoappendix, mesenteric and omental fat ("phlegmon") – Encapsulated fluid collection surrounding perforated appendix

Colon

TERMINOLOGY

MR Findings • Same general features as on CT ○ Thick-walled, dilated appendix ○ Periappendiceal inflammatory changes ○ Wall of inflamed appendix may be bright on diffusionweighted imaging • MR is a good alternative to CT in pregnant patients and children when US is nondiagnostic ○ MR is most appropriate and useful in the 2nd and 3rd trimesters – Enlarging uterus displaces appendix, making it more difficult to evaluate by US ○ Use of MR in 1st trimester is considered relatively contraindicated by some physicians

Ultrasonographic Findings • Grayscale ultrasound ○ Noncompressible appendix 7 mm – Measured from outer-to-outer wall ○ Sonographic McBurney sign with focal pain over appendix ○ Shadowing, echogenic appendicolith ○ Increased echogenicity of inflamed periappendiceal fat ○ RLQ fluid, phlegmon, abscess • Color Doppler ○ Increased flow within wall of appendix, indicating inflammation – Sensitivity 85%, specificity 90%

Imaging Recommendations • Best imaging tool ○ US is primary imaging method for – Pediatric age group – Women of reproductive age – Thin adults ○ CT performed for patients with inconclusive US ○ CT is procedure of choice for – Many adults – Elderly: Consider cecal or appendiceal tumor – Subacute symptoms or palpable mass □ Differentiation of inflammation, abscess, tumor • Protocol advice ○ CECT – Thin sections (1.25-2.5 mm), viewed in axial, coronal ± sagittal planes – Visualize early appendicitis (increased mural enhancement) – Helps to diagnose perforation with nonenhancement of necrotic portion of appendiceal wall – Helps to identify other inflamed bowel wall, abscesses ○ Oral contrast material can be helpful in identifying appendix 479

Colon

Appendicitis

– Opacification of distal ileal and cecal lumen; no (or incomplete) opacification of appendiceal lumen – Rectal contrast administration is rarely utilized ○ NECT may be adequate for patients with ample intraperitoneal fat

DIFFERENTIAL DIAGNOSIS Mesenteric Adenitis and Enteritis • Enlarged and clustered lymphadenopathy in mesentery and RLQ • May have ileal wall thickening due to enteritis • Pain when US transducer pressure applied over nodes or inflamed bowel • Diagnosis of exclusion: Appendicitis may also cause clustered lymphadenopathy and bowel wall thickening

Crohn Disease • CT: Longer segment of distal small bowel wall involvement

Gynecologic Causes • Ruptured corpus luteum (crenulated, "collapsed balloon" with enhancing wall) • Dilated fallopian tube with fluid-fluid level (pyosalpinx) • Loss of fat planes among pelvis organs (pelvic inflammatory disease) ○ Indefinite uterus sign with obscuration of posterior wall of uterus

Cecal Diverticulitis • Cecal diverticulum with mural thickening, high-density contents • Pericecal inflammatory changes

Appendiceal Tumor • Carcinoma, lymphoma, carcinoid • Soft tissue-density mass infiltrating &/or obstructing appendix • Usually little surrounding infiltration

Cecal Carcinoma • May obstruct appendiceal orifice • Dilated appendix, no periappendiceal inflammation • Circumferential cecal mass and lymphadenopathy suggest tumor rather than appendicitis

Cystic Fibrosis • Appendix may be distended, but uninflamed

PATHOLOGY General Features • Etiology ○ Obstructed appendiceal lumen – By appendicolith or hypertrophied Peyer patches

Staging, Grading, & Classification • Nonperforated • Perforated ○ May have surrounding periappendiceal abscess and soft tissue inflammation of mesentery and omentum

Gross Pathologic & Surgical Features • Distended appendix ± appendicolith 480

Microscopic Features • Pus in lumen; mucosal ulceration • Leukocyte infiltration of appendiceal wall • Necrosis if gangrenous

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Periumbilical pain migrating to RLQ ○ Peritoneal irritation at McBurney point ○ Anorexia, nausea, vomiting, diarrhea, possible fever ○ Atypical signs in > 1/3 of patients • Clinical profile ○ Highly variable and not reliable – Clinical diagnosis is incorrect in ~ 20% of young men and 40% of young women – Also frequently in error in young children and older adults

Demographics • Age ○ All ages affected • Gender ○ M=F • Epidemiology ○ 7% of all individuals in western countries develop appendicitis during their lifetimes

Natural History & Prognosis • Treatment ○ Surgery: For nonperforated or minimal perforation ○ Percutaneous drainage: Well-localized abscess > 3 cm ○ Antibiotic therapy: Periappendiceal soft tissue inflammation, no abscess • Complications ○ Gangrene and perforation, abscess formation ○ Peritonitis, septicemia ○ Pyelophlebitis of superior mesenteric or portal vein, ± hepatic abscess – More common in "smoldering," low-acuity cases with recurrent bouts of appendicitis • Prognosis ○ Excellent with early surgery

SELECTED REFERENCES 1.

2. 3.

4.

Kim Y et al: Increasing utilization of abdominal CT in the Emergency Department of a secondary care center: does it produce better outcomes in caring for pediatric surgical patients? Ann Surg Treat Res. 87(5):239-44, 2014 Smith MP et al: ACR Appropriateness Criteria® right lower quadrant painsuspected appendicitis. Ultrasound Q. ePub, 2014 Garcia K et al: Suspected appendicitis in children: diagnostic importance of normal abdominopelvic CT findings with nonvisualized appendix. Radiology. 250(2):531-7, 2009 Wan MJ et al: Acute appendicitis in young children: cost-effectiveness of US versus CT in diagnosis--a Markov decision analytic model. Radiology. 250(2):378-86, 2009

Appendicitis Colon

(Left) This young woman presented with acute abdominal and pelvic pain and had an inconclusive sonographic exam, CT, with oral and IV contrast medium, shows mural thickening at the base of the cecum . (Right) CT in the same case shows a thick-walled appendix with mural hyperenhancement but no luminal contrast medium.

(Left) Another CT section in the same case shows inflammation of the fat planes and nodes around the appendix . (Right) Coronal reformatted CT in the same case helps to identify the inflamed appendix and its retrocecal location, a common variant that may make it difficult to visualize the appendix on ultrasonography.

(Left) Axial CECT in this patient with appendicitis shows gas within a distended appendix , possibly due to an intraluminal gas-forming infection. Periappendiceal inflammatory changes are also evident. (Right) Axial CECT in the same patient shows prominent periappendiceal fat stranding , due to edema in the mesoappendix. The appendix is dilated and there is focal necrosis of its wall with an extraluminal gas bubble , indicating perforation.

481

Colon

Appendicitis

(Left) This 61-year-old man had atypical signs and symptoms of right abdominal pain. CT shows the inflamed appendix in an unusually medial position relative to the hepatic flexure of the colon. (Right) Another CT section in the same case shows typical signs of appendicitis, including the thickened, enhancing wall , and inflammation of the local fat and nodes .

(Left) A coronal reformatted CT in the same case helps to identify the inflamed appendix lying medial to the ascending colon . (Right) Another coronal CT image shows the appendix arising from the tip of the cecum . The inflamed portion of the appendix along with the inflamed fat and nodes are at some distance from the cecal tip, accounting for the atypical site of maximum tenderness on exam.

(Left) This woman presented in her second trimester of pregnancy with acute abdominal pain and fever. Following a nondiagnostic US exam she had an MR study. On these T2W images, the gravid uterus and fetus are evident along with a dilated, thick-walled appendix arising from the cecal tip. (Right) In the same case, a STIR image (top) and a diffusion-weighted image (bottom) show the edematous, thickened wall of the appendix that also shows restricted diffusion. Acute appendicitis was confirmed at surgery.

482

Appendicitis Colon

(Left) This young man had typical clinical and CT features of acute appendicitis, including the presence of 2 appendicoliths . He had a laparoscopic appendectomy. (Right) For several weeks following the appendectomy, the patient had persistent fever and RUQ pain. Repeat CT scan shows a perihepatic abscess surrounding a calcification identical in appearance to the larger of the 2 appendicoliths. This had been inadvertently "dropped" during the appendectomy and was the nidus for the perihepatic abscess.

(Left) This 27-year-old man had a 2-day history of progressive RLQ pain and fever. Axial CT shows extensive inflammation in the RLQ adjacent to the mucosal enhancing, thick-walled appendix . (Right) Another CT section in this case shows an encapsulated fluid collection (abscess) surrounding the collapsed, necrotic, perforated appendix .

(Left) A coronal reformatted CT section in the same case shows the inflamed, intact appendix and its necrotic portion within the abscess . (Right) Under CT guidance, a pigtail catheter was placed percutaneously, and a repeat CT scan shows effective drainage of the loculated fluid collection. This is a case of perforated tip appendicitis with a loculated periappendiceal abscess.

483

Colon

Mucocele of the Appendix KEY FACTS

TERMINOLOGY • Chronic cystic dilatation of appendiceal lumen caused by mucin accumulation

IMAGING • Classified into 3 types based on histology ○ Mucosal hyperplasia (simple mucocele) ○ Mucinous cystadenoma (most common) ○ Mucinous cystadenocarcinoma ( risk of perforation) • Pseudomyxoma peritonei ○ Due to rupture of mucocele, usually malignant rather than benign mucocele ○ Peritoneal cavity filled with mucus ○ Loculated ascites; scalloped surface of liver and spleen ○ Envelopes and obstructs bowel • Myxoglobulosis ○ Rare variant with multiple small globules ± calcifications • Mucocele ○ Calcification (curvilinear) within wall or lumen

(Left) Axial CECT in a 30-yearold woman with chronic and acute RLQ pain shows an ileocolic intussusception , with a cystic-appearing lead mass that has calcification within its wall. (Right) Another CT section in the same patient shows the intussusception and the mucocele that was the lead mass.

(Left) Gross pathology of the resected specimen in this case shows the intussusception and the mucocele . (Right) Gross pathology in the same patient shows the resected specimen opened to illustrate the characteristic mucinous content of the mucocele.

484

• Mucinous cystadenocarcinoma ○ Large irregular mass with thickened nodular wall

TOP DIFFERENTIAL DIAGNOSES • • • • •

Acute appendicitis (abscess) Appendiceal tumors Cecal carcinoma Ovarian cystic mass Cystic fibrosis

CLINICAL ISSUES • Rare • Complication: Rupture, torsion, intussusception • Treatment ○ Surgical resection (usually right hemicolectomy) • Prognosis ○ Simple mucocele and cystadenoma (good), carcinoma (poor) – Pseudomyxoma: Poor prognosis

Mucocele of the Appendix Colon

○ CT: Multiplanar reformations may be helpful to show relation of mass to cecal tip

TERMINOLOGY Definitions • Chronic cystic dilatation of appendiceal lumen by mucin accumulation

IMAGING General Features • Best diagnostic clue ○ Round or oval, thin-walled, cystic mass near tip of cecum • Size ○ Usually 3-6 cm in diameter • Other general features ○ Classified into 3 types based on histology – Focal or diffuse mucosal hyperplasia – Mucinous cystadenoma – Mucinous cystadenocarcinoma ○ Focal or diffuse mucosal hyperplasia (simple mucocele) – Resembles hyperplastic polyp of colon – Does not perforate ○ Mucinous cystadenoma – Benign neoplasm; most common type of mucocele – < 20% of cases perforate with mucus seeding ○ Mucinous cystadenocarcinoma – Less common than benign mucocele, but more likely to perforate and cause pseudomyxoma peritonei ○ Pseudomyxoma peritonei – Due to rupture of mucocele, usually malignant – Peritoneal cavity fills with mucus ○ Myxoglobulosis – Rare variant with multiple small globules – Calcify and produce 1-10 mm mobile calcifications

CT Findings • CECT ○ Simple mucocele – Well-defined cystic mass RLQ near water density – Calcification curvilinear within wall ○ Mucinous cystadenoma – Encapsulated low-attenuation cyst – Indistinguishable from simple mucocele by CT ○ Mucinous cystadenocarcinoma – Large, irregular mass with thickened nodular wall – Components: Solid and cystic; Ca++ in solid areas ○ Pseudomyxoma peritonei – Loculated ascites; scalloped surface of liver and spleen

DIFFERENTIAL DIAGNOSIS Acute Appendicitis (Abscess) • More inflammatory changes • Thick, irregular abscess wall

Appendiceal Tumors • Carcinoma: Mass obstructing lumen ± metastases • Lymphoma: Soft tissue density mass

Cecal Carcinoma • Dilated appendix without inflammation

Ovarian Cystic Mass • Distinguish by relation to broad ligament vs. cecal tip

Cystic Fibrosis • Appendix may become distended with inspissated secretions

PATHOLOGY General Features • Etiology ○ Obstructing lesions can cause mucocele formation – Postappendicitis scarring (most common) – Fecalith, appendiceal carcinoma, endometrioma – Carcinoid, polyp, volvulus, carcinoma of cecum • Associated abnormalities ○ Colonic adenocarcinoma (20% of patients with mucocele have concurrent colonic cancer) ○ Cystic fibrosis (appendiceal lumen occluded by inspissated mucus)

Gross Pathologic & Surgical Features • Mucocele: Thin-walled, mucin-filled cystic structure

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic; tender RLQ; palpable mass • Complications: Rupture, torsion, intussusception

Natural History & Prognosis • Simple mucocele & cystadenoma (good), carcinoma (poor) ○ Pseudomyxoma: Bad prognosis

MR Findings

Treatment

• Morphology: Oval or spherical pericecal mass ○ Contents are hypointense on T1WI, bright on T2WI

• Surgical resection (usually right hemicolectomy)

Ultrasonographic Findings • Grayscale ultrasound ○ Anechoic or cystic with internal echoes (septations) ○ Increased through-transmission is characteristic ○ Complex cystic mass ± calcification ○ Gravity-dependent echoes (inspissated mucus)

SELECTED REFERENCES 1.

2. 3.

Stark C et al: Preoperative assessment and treatment of appendiceal mucocele complicated by acute torsion: a case report. BMC Res Notes. 7:1, 2014 Demetrashvili Z et al: Mucocele of the appendix: case report and review of literature. Int Surg. 97(3):266-9, 2012 Lim HK et al: Primary mucinous cystadenocarcinoma of the appendix: CT findings. AJR Am J Roentgenol. 173(4):1071-4, 1999

Imaging Recommendations • Protocol advice 485

Colon

Mucocele of the Appendix

(Left) In this 65-year-old man with pelvic fullness and frequent need to urinate, axial NECT shows a large cystic mass that might be mistaken for the urinary bladder. (Right) Another CT section in the same patient shows that the wall of this mass is partially calcified , which is a characteristic feature of a mucocele. The urinary bladder is displaced and compressed.

(Left) Coronal reformatted CT in the same patient shows the large cystic mass and its curvilinear mural calcification . (Right) Another coronal CT image in the same patient shows the large mucocele and the displaced, compressed urinary bladder .

(Left) Axial CECT in a 35-yearold man with cystic fibrosis shows marked dilation of small bowel due to distal intestinal obstruction syndrome (DIOS). There is also a pericecal oval mass with peripheral calcification. (Right) Coronal reformatted CECT in the same patient shows the pericecal mucocele . The colon is opacified by water-soluble contrast medium previously administered as a "cleansing enema."

486

Mucocele of the Appendix Colon

(Left) Endoluminal view from a CT colonography study in an 82-year-old man shows a polypoid mass within the lumen of the cecum. (Right) Axial 2D image from the same study shows a polypoid mass of near-water density within the cecal lumen with an extraluminal component that is tubular and well encapsulated.

(Left) A standard diagnostic CT scan was subsequently performed and shows the same well-defined, waterdensity mass within the cecum. (Right) Another CT section from the same patient shows the tubular extraluminal component of the mass. At surgery, a benign mucocele of the appendix was resected, a portion of which had invaginated itself into the lumen of the cecum.

(Left) This 61-year-old man had a malignant mucocele of the appendix resected several months previously, now presenting with a distended abdomen. Axial CECT shows complex ascites with a scalloped surface of the liver and spleen, typical features of pseudomyxoma peritonei. (Right) Another CT from the same patient shows typical features of pseudomyxoma peritonei, with complex, higher-than-water-density fluid throughout the peritoneal cavity.

487

Colon

Colonic Diverticulosis KEY FACTS

TERMINOLOGY

PATHOLOGY

• Outpouching of colonic mucosa and submucosa, most commonly in sigmoid colon

• Etiology ○ Sedentary lifestyle, high-fat, low-fiber diet predispose to diabetes, obesity, and diverticulosis among other ailments

IMAGING • Best imaging tools: CT and barium enema ○ CT shows diverticula as outpouchings from colonic wall, filled with gas or feces ○ Circular muscle hypertrophy (myochosis coli) causes irregularly spaced indentations and narrowing of lumen of colon

TOP DIFFERENTIAL DIAGNOSES • Giant sigmoid diverticulum ○ Represents chronic, walled-off abscess that communicates with colonic lumen • Diverticulitis ○ Due to perforation of 1 or more diverticula

(Left) Axial NECT in a 74-yearold man with a 10-year history of obstipation presenting with lower abdominal pain shows a large amount of stool in the sigmoid colon and a cluster of gas-filled diverticula in the descending colon. (Right) Axial CECT in the same patient illustrates the normal fat planes of the sigmoid mesocolon and the small bowel mesentery , without evidence of mural thickening or pericolonic stranding to suggest diverticulitis.

(Left) Axial CECT in a patient presenting with constipation and intermittent painful lower abdominal cramps shows thickening of the sigmoid colon wall due to myochosis, a combination of hypertrophy of the circular muscle layer, shortening of the taeniae, and lumen narrowing. (Right) Spot film from an aircontrast BE shows distortion of the colonic lumen. The luminal outpouchings are diverticula, while the irregularly spaced infoldings of the wall represent myochosis (circular muscle hypertrophy).

488

CLINICAL ISSUES • Affects > 50% of population > 60 years of age in USA • Most common colonic disease in Western world ○ Diverticulosis is increasing in prevalence parallel to obesity epidemic ○ Diverticulosis in patients 20-40 years old is no longer rare • Most common signs/symptoms ○ Most often asymptomatic ○ Alternating constipation and diarrhea (with circular muscle hypertrophy) ○ Most common cause of rectal bleeding in patients > 40 years of age ○ Diverticulitis or abscess

Colonic Diverticulosis

Synonyms • Diverticular disease

Definitions • Outpouching of colonic mucosa and submucosa, most commonly in sigmoid colon • Myochosis coli is uncommonly used term to describe foreshortening of colon and circular muscle hypertrophy that commonly occurs along with diverticulosis

IMAGING General Features • Best diagnostic clue ○ Rounded or oval colonic wall outpouchings • Location ○ Primarily sigmoid colon, but may occur in any segment except rectum – Lack of diverticula in rectum is due to fusion of taenia providing strong supporting coat to rectal wall • Size ○ 5-10 mm in diameter

Imaging Recommendations • Best imaging tool ○ CT and barium enema (BE)

Fluoroscopic Findings • Contrast enema ○ Diverticula project out beyond wall of colon ○ Circular muscle hypertrophy (myochosis coli) causes irregularly spaced indentations and narrowing of lumen of colon ○ Easier to distinguish colonic diverticula from polyps on single contrast BE than on air-contrast BE – Diverticula fill with barium on single contrast BE – Diverticulum with large neck; may resemble sessile polyp on air-contrast BE – Appearance of diverticula varies depending on degree of air vs. barium in diverticulum

CT Findings • Outpouchings (diverticula) filled with air, stool, or contrast agent • Mural thickening due to myochosis (circular muscle hypertrophy) usually > 4 mm ○ Causes irregular narrowing of colonic lumen • No pericolonic fluid, gas, or fat stranding

DIFFERENTIAL DIAGNOSIS Giant Sigmoid Diverticulum • Rare complication of diverticulitis • Results from subserosal or pericolonic perforation of a diverticulum ○ Inflammation and granulation tissue replace mucosa ○ Represents a chronic, walled-off abscess that communicates with colonic lumen ○ Communication with lumen accounts for filling of this lesion with gas and enteric contrast evident on CT and BE

• Air trapping with formation of air-filled retention cystic space • Size varies from 5-20 cm • Plain films demonstrate large, rounded, air-filled cavity in pelvis &/or lower abdomen • Surgery is indicated if symptomatic, as these persist and recur

Colon

TERMINOLOGY

Colonic Polyps • More likely to be confused for diverticula on air-contrast barium enema ○ Bowler hat sign seen in both ○ If "bowler hat" points to center of lumen, represents polyp ○ Polyps cast negative shadow in barium pool ○ Polyps do not demonstrate fluid levels on upright views ○ Polyps do not show barium filling

Diverticulitis • Multiple diverticula • Long segment (> 10 cm) of lumen narrowing and wall thickening • Pericolonic fat stranding and engorged vessels in sigmoid mesentery • Fluid at base of sigmoid mesentery

Sigmoid Ischemic Colitis • Submucosal hemorrhage ○ "Thumbprinting" on plain films and contrast enema • Etiology: Low-flow states, hypotension ○ Sigmoid is second to splenic flexure as "watershed" site of hypoperfusion type of colonic ischemia • May lead to stricture or perforate

PATHOLOGY General Features • Etiology ○ Advanced age (although mean age at onset is decreasing) – Diverticulosis in patients 20-40 years old is no longer rare ○ Diet low in fiber and high in red meat and fat ○ Pressure gradient between lumen and serosa of colon – Areas of relative bowel wall weakness occur at sites of penetration of vasa rectae – Colonic wall weakest on either side of taenia mesocolica and mesenteric side of taenia libera and taenia omentis – As diverticulum expands, it pushes out vasa rectae of bowel wall □ Inflammation and microperforation of apex of diverticulum erodes into artery, causing hemorrhage □ Micro- or macroperforation constitutes diverticulitis • Associated abnormalities ○ Metabolic syndrome – Sedentary lifestyle, high-fat, low-fiber diet predispose to diabetes, obesity, and diverticulosis among other ailments – Diverticulosis is increasing in prevalence parallel to obesity epidemic 489

Colon

Colonic Diverticulosis ○ Colonic bleeding – 25% of patients have recurrent bleeding ○ Diverticulitis or abscess ○ Connective tissue disorders (Marfan syndrome)

Natural History & Prognosis • Complications in 10-25% of cases ○ Bleeding and diverticulitis are most common complications

Staging, Grading, & Classification

Treatment

• Earliest stage ○ Scattered sigmoid diverticula • Moderate stage ○ Smooth muscle hypertrophy of sigmoid, more diverticula • Advanced stage ○ Extensive involvement of ascending and descending colon

• High-fiber diet • Fiber supplements • Reduce red meat consumption

Gross Pathologic & Surgical Features • Herniated mucosal and submucosal layers • Thickening of circular smooth muscle (myochosis coli) ○ Shortening of taenia ○ Narrowing of lumen • Diverticula are often filled with inspissated stool

Microscopic Features • Increased lymphoid follicles due to lack of muscularis propria in diverticulum

DIAGNOSTIC CHECKLIST Consider • Diverticulitis if pericolonic fat stranding and fluid are seen on CT • Colon cancer if patient has rectal bleeding

SELECTED REFERENCES 1. 2.

3. 4.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most often asymptomatic ○ May have symptoms of irritable bowel syndrome (alternating constipation and diarrhea) – Circular muscle hypertrophy narrows colic lumen – Makes passage of hard stool difficult – Patients may report diarrhea as frequent need to pass small amounts of less firm stool that is able to pass through narrowed colonic lumen ○ Rectal bleeding ○ Diverticulitis – Fever, lower abdominal tenderness, pain • Other signs/symptoms ○ Pain with defecation ○ Postprandial pain ○ Bloating ○ Decreased caliber of stools

Demographics • Age ○ Increased incidence after 40 years – Becoming increasingly common in 20-45 year-old group – Prevalence has increased > 25% within past decade ○ Affects > 50% of population > 60 years of age in USA • Gender ○ M=F • Epidemiology ○ Most common colonic disease in Western world – Exact prevalence is difficult to know because most patients are asymptomatic ○ Most common cause of rectal bleeding in patients > 40 years of age 490

5. 6. 7.

8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

Aytac E et al: Risk of recurrence and long-term outcomes after colonic diverticular bleeding. Int J Colorectal Dis. 29(3):373-8, 2014 Choi YH et al: Do we need colonoscopy following acute diverticulitis detected on computed tomography to exclude colorectal malignancy? Dig Dis Sci. 59(9):2236-42, 2014 Humes DJ et al: Review article: The pathogenesis and management of acute colonic diverticulitis. Aliment Pharmacol Ther. 39(4):359-70, 2014 Vanderstappen JH et al: A rare complication of colonic diverticulosis: giant diverticulum. Case report and overview of pathophysiology, diagnosis and therapeutic options. Acta Chir Belg. 114(3):206-8, 2014 Hirata T et al: Association between colonic polyps and diverticular disease. World J Gastroenterol. 14(15):2411-3, 2008 Martel J et al: History, incidence, and epidemiology of diverticulosis. J Clin Gastroenterol. 42(10):1125-7, 2008 Meurs-Szojda MM et al: Diverticulosis and diverticulitis form no risk for polyps and colorectal neoplasia in 4,241 colonoscopies. Int J Colorectal Dis. 23(10):979-84, 2008 Morini S et al: Diverticulosis and colorectal cancer: between lights and shadows. J Clin Gastroenterol. 42(7):763-70, 2008 Comparato G et al: Diverticular disease in the elderly. Dig Dis. 25(2):151-9, 2007 Rispo A et al: Lower prevalence of diverticulosis in patients with ulcerative colitis. Dis Colon Rectum. 50(8):1164-8, 2007 Brian West A: The pathology of diverticulosis: classical concepts and mucosal changes in diverticula. J Clin Gastroenterol. 40 Suppl 3:S126-31, 2006 Dobbins C et al: The relationship of obesity to the complications of diverticular disease. Colorectal Dis. 8(1):37-40, 2006 Krones CJ et al: The rare epidemiologic coincidence of diverticular disease and advanced colonic neoplasia. Int J Colorectal Dis. 21(1):18-24, 2006 Sultan K et al: The nature of inflammatory bowel disease in patients with coexistent colonic diverticulosis. J Clin Gastroenterol. 40(4):317-21, 2006 Gollub MJ et al: CT colonography features of sigmoid diverticular disease. Clin Imaging. 29(3):200-6, 2005 Kang JY et al: Epidemiology and management of diverticular disease of the colon. Drugs Aging. 21(4):211-28, 2004 Simpson J: Recent advances in diverticular disease. Curr Gastroenterol Rep. 6(5):417-22, 2004 West AB et al: The pathology of diverticulosis coli. J Clin Gastroenterol. 38(5 Suppl):S11-6, 2004

Colonic Diverticulosis Colon

(Left) This 21-year-old woman was obese and diabetic, with complaints of alternating constipation and diarrhea. Numerous diverticula are evident, projecting from the surface of the sigmoid colon. (Right) Another CT section in this case shows additional diverticula . Along with the epidemic of obesity, diverticulosis is now seen even among young adults such as this young woman. Both obesity and diverticulosis are related to a diet high in fat and low in fiber, and both are more common among inactive individuals.

(Left) This 75-year-old man had rectal bleeding (hematochezia). An axial NECT section shows right colonic diverticula . (Right) An arterial phase CECT image in the same case shows active extravasation of blood into the lumen of the ascending colon, essentially diagnostic of an acute and severe hemorrhage from diverticulosis.

(Left) A coronal-reformatted image from the same case shows the accumulation of opacified blood within the lumen of the colon. Also note the right-side diverticula. (Right) A film from the superior mesenteric angiogram confirms active bleeding into the lumen of the colon from a branch of the right colic artery. Diverticulosis is a relatively common cause for rectal hemorrhage.

491

Colon

Diverticulitis KEY FACTS

TERMINOLOGY • Intramural and pericolonic infectious/inflammatory process resulting from perforation of colonic diverticula

• Radiation colitis • Ischemic colitis • Pseudomembranous colitis

IMAGING

CLINICAL ISSUES

• Simple or uncomplicated diverticulitis ○ Multiple colonic diverticula and colonic wall thickening ○ Inflammation of pericolonic fat (stranding) ○ Thickened base of sigmoid mesocolon ○ Engorged mesocolic blood vessels ○ "Microperforation": Small bubbles of pericolonic gas • More complicated diverticulitis ○ More extensive extraluminal collections of gas and fluid ○ Free intraperitoneal spread of gas or fluid ○ Fistulas to skin or hollow viscera ○ Infectious thrombophlebitis (pylephlebitis)

• Most common colonic disease in Western world • Average age at onset is dropping ○ Related to obesity, metabolic syndrome, poor diet • Percutaneous abscess drainage can obviate surgery or allow elective 1-step procedure in most cases

TOP DIFFERENTIAL DIAGNOSES • Colon carcinoma

(Left) Graphic illustrates sigmoid diverticula, luminal narrowing, and wall thickening (circular muscle hypertrophy). There is a pericolic abscess due to the perforated diverticulum, but the rectum is spared. (Right) Axial CECT shows uncomplicated sigmoid diverticulitis with irregular luminal narrowing and wall thickening, numerous gasfilled diverticula , and relatively mild infiltration of the pericolonic fat .

(Left) Axial CECT in a 60-yearold woman presenting with lower abdominal pain, fever, and tenderness demonstrates extensive free intraperitoneal gas . (Right) Axial CECT in the same patient shows fluid that has loculated into abscesses . At surgery extensive sigmoid diverticulosis was discovered to be the source of the free air and abscesses. This amount of free intraperitoneal air is unusual as the omentum usually walls off the perforated diverticulum.

492

DIAGNOSTIC CHECKLIST • Long segment colonic involvement, extensive inflammatory changes, and absence of nodes or metastases favor diverticulitis over colon cancer • In some patients, it is difficult to distinguish diverticulitis from colon cancer; these should have follow-up endoscopy following resolution of acute symptoms

Diverticulitis

Definitions • Intramural and pericolonic infectious/inflammatory process resulting from perforation of colonic diverticula.

IMAGING General Features • Best diagnostic clue ○ Diverticula, infiltrated pericolonic fat and engorged vessels, ± extraluminal gas and fluid • Location ○ Most common in sigmoid colon (> 90% of cases) ○ Diverticula occur mainly where vasa recta vessels pierce muscularis propria, between mesenteric and antimesenteric taeniae • Colonic diverticula are pseudodiverticular ○ Saccular outpouchings of mucosa and submucosa, 5-10 mm in diameter

Fluoroscopic Findings • Single contrast barium enema ○ Generally contraindicated in acute setting ○ Numerous diverticula are usually present as outpouchings from lumen ○ Colonic lumen is narrowed with serrated or "cog wheel" appearance – Latter may represent spasm or result of circular muscle hypertrophy (not necessarily indicative of active inflammation)

□ Enhancing tract with gas &/or enteric contrast material evident within bladder, vagina, etc. – Infectious thrombophlebitis □ Mesenteric vein becomes contaminated with colonic bacteria □ May be evident as venous wall enhancement, luminal gas, or thrombosis □ May carry gas and bacteria to portal vein and liver (potentially causing pyogenic hepatic abscess)

Colon

TERMINOLOGY

Ultrasonographic Findings • Pericolic inflammation ○ Increased echogenicity ± ill-defined hypoechoic areas • Pericolic abscess ○ Hypoechoic ± internal echoes • Color and power Doppler ○ Hyperemia of pericolonic fat

Imaging Recommendations • Best imaging tool ○ Multiplanar CECT – Rectal contrast may be useful to demonstrate colonic fistulas

DIFFERENTIAL DIAGNOSIS Colon Carcinoma • Short segment involvement (< 10 cm), wall thickness > 2 cm, mesenteric lymphadenopathy, metastases • Asymmetric bowel wall thickening ± irregular surface • Less pericolonic infiltration and vessel engorgement

CT Findings

Radiation Colitis

• Diverticulosis ○ Multiple air-, contrast-, or stool-filled outpouchings (diverticula) ○ Colonic wall is often thickened – May be due to circular muscle hypertrophy, not necessarily acute diverticulitis • Diverticulitis ○ Simple or uncomplicated diverticulitis – Multiple colonic diverticula and colonic wall thickening □ Long segmental (> 10 cm) colonic involvement – Inflammation of pericolonic fat (stranding) □ Inflammation is usually localized by adherence of omentum – Thickened base of sigmoid mesocolon; curvilinear line in left iliac fossa – Engorged mesocolic blood vessels – "Microperforation": Small bubbles of pericolonic gas ○ More complicated diverticulitis – More extensive extraluminal collections of gas &/or fluid ( "macroperforation") □ May loculate as abscess with contrast-enhancing wall – Free intraperitoneal spread of gas or fluid □ Represents failure of omentum to wall off perforation □ Generally requires surgical intervention for peritoneal soiling – Fistulas to skin or hollow viscera

• Barium enema ○ Acute radiation colitis/proctitis – Disrupted/distorted mucosal pattern (edema or hemorrhage) ○ Chronic radiation colitis/proctitis – Diffuse or focal narrowing with tapered margins – Colonic stricture or fistula – Widened presacral space • CT ○ More uniform wall thickening + luminal narrowing, less pericolonic inflammation than diverticulitis ○ Colonic luminal narrowing or stricture, ± sinuses or fistulas • Diagnosis: History of radiation therapy; sigmoidoscopy

Ischemic Colitis • Usual sites: Splenic flexure > rectosigmoid junction • Barium enema ○ Thumbprinting (usually within 24 hours) due to submucosal edema or hemorrhage ○ Ulceration: Sloughing of mucosa, usually 1-3 weeks after onset • CT ○ More uniform, extensive wall thickening, less pericolonic infiltration than diverticulitis ○ Hypoattenuated bowel wall: Submucosal or diffuse edema ○ Hyperattenuated bowel wall: Submucosal or diffuse bleeding 493

Colon

Diverticulitis ○ ± pneumatosis and portomesenteric venous gas • Diagnosis: History of nonocclusive vascular disease, hypoperfusion in elderly (CHF, arrhythmia, shock, drugs)

Pseudomembranous Colitis • Massive wall thickening, usually pancolonic • Mucosal hyperenhancement with submucosal edema ○ Accordion sign: Enhancing mucosa or enteric contrast compressed by edematous folds

PATHOLOGY General Features • Etiology ○ Fecal impaction at mouth of diverticulum with subsequent perforation ○ Contributing factors to development of diverticula – Pressure gradient between lumen and serosa (sigmoid) □ Narrowest lumen of sigmoid colon + increased pressure + dehydrated stool – Bowel wall weakness between mesenteric and antimesenteric taeniae • Diverticulitis is most common complication of diverticulosis ○ Occurs in 30% of patients with moderate diverticulosis

Microscopic Features • Diverticula: Mucosal and submucosal herniation through defect in circular layer of muscle • Diverticulitis: Perforation with inflammation and micro/macroabscess

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Diverticulitis – LLQ colicky pain, tenderness, palpable mass – Fever, altered bowel habits ○ Diverticulosis – Often asymptomatic – Alternating constipation and diarrhea due to luminal narrowing – Pain and rectal bleeding (30% of cases) ○ Lab data: Elevated WBC count, anemia, ± blood in stool

Demographics • Age ○ 5th-8th decade (peak), though frequently occurs in younger patients ○ Average age at onset is dropping – Related to obesity, metabolic syndrome, poor diet • Gender ○ M=F • Epidemiology ○ > 50% of patients over 50 years of age have diverticulosis (in USA) ○ Can occur in young adults (< 30 years of age) ○ Most common colonic disease in Western world ○ Rare in less developed countries (less processed food, diet with higher fiber content) 494

Natural History & Prognosis • Diverticular disease of colon is sequential ○ Prediverticular phase: Circular muscular thickening of colonic wall (myochosis) ○ Diverticulosis: Frank outpouchings (diverticula) ○ Diverticulitis: Perforation and localized pericolonic inflammation or abscess • Complications ○ Local or hepatic abscess, fistulas, generalized peritonitis ○ Obstruction, hemorrhage (uncommon) ○ Pylephlebitis (portal vein thrombus), liver abscesses ○ Immunocompromised at increased risk for peritonitis, sepsis • Prognosis: Good if in early stage or treated with surgery

Treatment • • • •

High-fiber diet (preventive) Antibiotics, IV fluids, bowel rest Emergent surgery for fecal peritonitis Percutaneous abscess drainage can obviate surgery or allow elective 1-step procedure in most cases

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Bowel wall thickening, pericolonic infiltration, and fat stranding affecting sigmoid colon • Long segment colonic involvement, extensive inflammatory changes, and absence of nodes or metastases favors diverticulitis over colon cancer ○ In some patients, it is difficult to distinguish diverticulitis from colon cancer; these should have follow-up endoscopy following resolution of acute symptoms

SELECTED REFERENCES 1.

2. 3. 4. 5.

6. 7. 8. 9.

10. 11. 12. 13.

Choi YH et al: Do we need colonoscopy following acute diverticulitis detected on computed tomography to exclude colorectal malignancy? Dig Dis Sci. 59(9):2236-42, 2014 de Vries HS et al: Routine colonoscopy is not required in uncomplicated diverticulitis: a systematic review. Surg Endosc. 28(7):2039-47, 2014 Jackson JD et al: Systematic review: outpatient management of acute uncomplicated diverticulitis. Int J Colorectal Dis. 29(7):775-81, 2014 Kechagias A et al: The role of C-reactive protein in the prediction of the clinical severity of acute diverticulitis. Am Surg. 80(4):391-5, 2014 Sallinen VJ et al: Nonoperative management of perforated diverticulitis with extraluminal air is safe and effective in selected patients. Dis Colon Rectum. 57(7):875-81, 2014 Ames JT et al: Septic thrombophlebitis of the portal venous system: clinical and imaging findings in thirty-three patients. Dig Dis Sci. 56(7):2179-84, 2011 Etzioni DA et al: Diverticulitis in the United States: 1998-2005: changing patterns of disease and treatment. Ann Surg. 249(2):210-7, 2009 Janes SE et al: Management of diverticulitis. BMJ. 332(7536):271-5, 2006 Zaidi E et al: CT and clinical features of acute diverticulitis in an urban U.S. population: rising frequency in young, obese adults. AJR Am J Roentgenol. 187(3):689-94, 2006 Salzman H et al: Diverticular disease: diagnosis and treatment. Am Fam Physician. 72(7):1229-34, 2005 Tack D et al: Suspected acute colon diverticulitis: imaging with low-dose unenhanced multi-detector row CT. Radiology. 237(1):189-96, 2005 Gore RM et al: Helical CT in the evaluation of the acute abdomen. AJR Am J Roentgenol. 174(4):901-13, 2000 Horton KM et al: CT evaluation of the colon: inflammatory disease. Radiographics. 20(2):399-418, 2000

Diverticulitis Colon

(Left) This 67-year-old man presented with LLQ pain and fever. CT demonstrates mural thickening , a diverticulum , and fluid collecting at the base of the sigmoid mesentery , typical features of uncomplicated diverticulitis. (Right) Axial CECT in the same patient illustrates the presence of engorged pericolonic vessels due to hyperemia of the inflamed pericolonic fat, another characteristic feature of acute diverticulitis.

(Left) This obese young woman (33 years old) presented with LLQ pain and fever. CT shows extensive inflammation surrounding the descending colon, as well as excessive subcutaneous fat. (Right) Coronal CT in the same case shows long segmental thickening of the wall of the descending colon, pericolonic inflammation , and numerous diverticula . Diverticulitis has become more common in younger individuals as part of the obesity and metabolic syndrome epidemic.

(Left) This 80-year-old man presented with abdominal pain and pneumaturia. CECT shows extensive sigmoid diverticulosis and inflammation of the surrounding tissues. (Right) Axial CT in the same patient shows a collection of gas and fluid bridging the inflamed colon and the thick-walled bladder , which contains gas. Colovesical fistula is a relatively common complication of diverticulitis.

495

Colon

Diverticulitis

(Left) This 50-year-old woman presented with acute RLQ pain and fever. CT shows inflamed fat and thickened fascial planes adjacent to the cecum and ascending colon. Several diverticula are noted . The appendix was normal on other sections (not shown). (Right) Coronal-reformatted CT in the same patient shows the inflammatory infiltrate surrounding the thick-walled ascending colon, typical features of right-sided diverticulitis.

(Left) This 50-year-old woman developed a foul-smelling vaginal discharge a few years following an uncomplicated hysterectomy. CT shows sigmoid colonic wall thickening . Numerous diverticula and pericolonic stranding were better seen on other sections. (Right) CT in the same patient shows rectally administered contrast material , some of which has entered the vagina along with gas.

(Left) Another CT section in the same patient shows the rectally-administered contrast material distending the lumen of the vagina . (Right) A sagittally-reformatted CT section in the same patient shows the colovaginal fistula and contrast medium within the vagina . At surgery, the fistula was determined to be due to diverticulitis that had infected the scar from the hysterectomy.

496

Diverticulitis Colon

(Left) This 42-year-old man had an hepatic mass on a recent CT. Arterial phase CT shows a segmental THAD throughout the posterior right lobe segments. The mass appears hypovascular on this phase. (Right) A portal venous phase CT shows resolution of the THAD and better defines the mass as an encapsulated, multiseptate lesion, characteristic of a pyogenic abscess.

(Left) A more caudal section in the same case shows the abscess as a typical collection of nonenhancing pus surrounded by enhancing septa and peripheral walls. (Right) A more caudal section in the same patient shows occlusion of the posterior branch of the right portal vein , accounting for the segmental THAD seen on arterial phase CT.

(Left) Another CT section in the same patient shows a filling defect within the lumen of the inferior mesenteric vein , the result of septic thrombophlebitis and diverticulitis. (Right) Another CT section in the same case shows diverticula and mild pericolonic infiltration , consistent with diverticulitis, which was the source of the septic phlebitis and hepatic abscess. Low acuity, but persistent diverticulitis is a relatively common cause of portal thrombophlebitis and liver abscess.

497

Colon

Epiploic Appendagitis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Acute inflammation or infarction of epiploic appendages

• Omental infarction ○ Appears as larger (3-5 cm) ball of "dirty" fat adjacent adjacent to ascending colon • Diverticulitis • Infectious colitis ○ Long segmental or pancolitis • Ulcerative colitis • Acute appendicitis

IMAGING • Best diagnostic clue: Small, oval pericolonic fatty nodule with hyperdense ring and surrounding inflammation • More common in left lower quadrant ○ Rectosigmoid (57%), ileocecal (26%), ascending colon (9%) • CT findings ○ Pericolonic oval fat-containing mass with thin hyperattenuating ring ○ ± central "dot" of increased attenuation within inflamed appendage (thrombosed vein) ○ Infarcted EA: Likely accounts for smooth calcified "stones" occasionally found in dependent peritoneal recesses • Best imaging test: CECT, preferably with multiplanar reformations

(Left) Graphic illustrates 2 normal epiploic appendages and 1 that is twisted and infarcted . (Right) CT in a young man with epiploic appendagitis and presenting with acute pelvic pain shows a small, oval mass adjacent to the sigmoid colon. It has a fat-density core and a contrast-enhanced rim, with inflammation of the adjacent mesenteric fat. The adjacent colon appears normal.

(Left) In this 36-year-old man with acute LLQ pain, CT shows a small, oval, fat-density lesion adjacent to the surface of the descending colon. The lesion has a thin, enhanced capsule, and there is a thin linear density in its center that probably represents the thrombosed vein at the center of an infarcted epiploic appendage. (Right) A coronal CT image in the same case shows the oval, encapsulated, infarcted epiploic appendage . The surrounding fat is inflamed, but the descending colon itself appears normal.

498

CLINICAL ISSUES • Closely mimics diverticulitis and other acute inflammatory conditions ○ Occurs in all age groups ○ Diagnosis is definitive by CT; obviates surgery

Epiploic Appendagitis

Abbreviations

○ Solid, hyperechoic, noncompressible, ovoid mass adherent to colonic wall surrounded by hypoechoic ring corresponding to density ring on CT

• Epiploic appendagitis (EA)

Imaging Recommendations

Definitions

• Best imaging tool ○ CECT, preferably with multiplanar reformations

• Acute inflammation or infarction of epiploic appendages • Primary EA: No other underlying inflammatory condition • Secondary EA: Appendages may be inflamed due to adjacent process, such as diverticulitis or abdominal abscess

IMAGING General Features • Best diagnostic clue ○ Small, oval, pericolonic fatty nodule with hyperdense ring and surrounding inflammation • Location ○ LLQ > RLQ – Rectosigmoid (57%), ileocecal (26%), ascending (9%) – Transverse colon (6%), descending colon (2%) • Morphology ○ Epiploic appendages: Small adipose structures protruding from serosal surface of colon • Other general features ○ Rarely diagnosed clinically but highly characteristic CT features ○ CT usually allows confident distinction from other GI or GU inflammatory processes

CT Findings • Normal epiploic appendages ○ Small lobulated masses of pericolonic fat, most evident in rectosigmoid colon ○ Seen on CT only when outlined by ascites • Appendagitis: 1-4 cm, ovoid, fat-density paracolic lesion with adjacent fat stranding • Thickened/compressed bowel wall, thickened visceral and parietal peritoneum • ± central "dot" of increased attenuation within inflamed appendage (thrombosed vein) • Hyperattenuating ring sign: Characteristic finding on CECT ○ Pericolonic oval fat-containing mass with thin hyperattenuating ring ○ Ring: Thickened visceral peritoneum of inflamed epiploic appendage ○ May calcify when infarcted and separate from colonic surface • Infarcted EA: Likely accounts for smooth calcified "stones" occasionally found in dependent peritoneal recesses

MR Findings • T1 and T2 breath-held spoiled gradient echo (SGE) images ○ signal lesion, hypointense central dot, thin hypointense ring • T1 C+ fat-suppressed gradient echo image ○ ring enhancement

Ultrasonographic Findings • Grayscale ultrasound

Colon

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Omental Infarction • Appears as larger (3-5 cm) ball of "dirty" fat • Occurs most commonly adjacent to ascending colon • Distinction from EA is not critical as both entities are selflimited

Diverticulitis • CT ○ Most common in sigmoid colon ○ Bowel wall and fascial thickening, luminal narrowing; pericolonic fat stranding, ± free fluid and air ○ Pericolic inflammatory changes: Abscess, sinuses, fistulas ○ Diverticular orifice edema (arrowhead sign) • Barium enema ○ Focal eccentric luminal narrowing, marked thickening and distortion of haustral folds ○ Colonic obstruction with zone of transition; intramural fistulous tract ("double track")

Appendicitis • CT ○ Appendicolith (usually calcified) within distended tubular appendix ○ Distended enhancing appendix with surrounding inflammation (fat stranding) ○ Wall thickening of cecum or terminal ileum, RLQ lymphadenopathy ○ Perforation: Fluid collection in RLQ or dependent pelvis (cul-de-sac), abscess, small bowel obstruction • Ultrasound ○ Echogenic appendicolith with posterior shadowing; fluid or abscess collection in RLQ ○ Noncompressible blind-ending tubular structure > 7 mm diameter

Infectious Colitis • e.g., Clostridium difficile colitis • Usually long segmental or pancolitis • CT ○ Colonic mucosal hyperenhancement, submucosal edema; ascites common ○ Accordion sign: Enteric contrast trapped between thickened colonic folds

Ulcerative Colitis • CT: Long segmental or pancolitis ○ Rectum involved, unlike in EA ○ Mucosal hyperenhancement, vessel engorgement ○ Less submucosal edema than with infectious colitis • Contrast enema: Continuous, not transmural, pseudopolyps, crypt microabscesses ○ Pancolitis with haustration, multiple ulcerations 499

Colon

Epiploic Appendagitis ○ Colorectal narrowing, presacral space > 1.5 cm and diffuse, symmetric colonic wall thickening ○ Mucosal islands or inflammatory pseudopolyps ○ Distal ileum involvement in backwash ileitis

PATHOLOGY General Features • Etiology ○ Torsion, venous thrombosis of appendages ○ Spontaneous venous thrombosis of draining appendageal vein ○ Predisposing factors for torsion and infarction – Precarious blood supply from colic arterial branches – Pedunculated morphology, mobility • Small pouches of peritoneum protruding from serosal surface of colon filled with fat, small vessels ○ Seen along free tenia and tenia omentalis, between cecum and sigmoid colon

Treatment

Gross Pathologic & Surgical Features

• Pericolonic ovoid fatty mass (1-4 cm) with hyperdense rim (most common in rectosigmoid area) • Not limited to left colon or elderly • Be alert for secondary EA in which appendages may be inflamed due to adjacent inflammatory process, such as diverticulitis

• Oval, fat-containing paracolic lesion, fat stranding, thickened wall

Microscopic Features • Visceral peritoneal lining of inflamed epiploic appendage covered with fibrinoleukocytic exudates • Fat necrosis within appendage

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Sudden onset focal abdominal pain, usually LLQ or RLQ ○ pain with coughing, deep breathing, abdominal stretching ○ Symptoms usually subside within 1 week of onset ○ Physical exam: Localized tenderness, no rigidity, some guarding ○ Lab data – WBC count normal or slightly in most cases

Demographics • Age ○ Typically seen in obese patients in 2nd to 5th decades of life; can occur in children • Gender ○ M=F • Epidemiology ○ Uncommon inflammatory and ischemic condition – Was rarely diagnosed in pre-CT era, but this is not a rare entity ○ Seen in 2.3-7.1% of clinically suspected colonic diverticulitis cases ○ Reported in 1% of suspected appendicitis cases

Natural History & Prognosis • Complications ○ Infarction of epiploic appendage ○ Intraperitoneal loose bodies – May remain as small (~ 1cm) spherical, peripherally calcified, free intraperitoneal bodies 500

– May grow by accretion into large objects the size and shape of a chicken egg ○ Recurrent inflammatory episodes (unusual) • Prognosis ○ Usually a benign self-limiting process – Spontaneous resolution within 1 week ○ Good prognosis after medical or surgical treatment • Conservative treatment with analgesics • Simple ligation and excision of infarcted epiploic appendage (rarely required if accurately diagnosed)

DIAGNOSTIC CHECKLIST Consider • Differentiate epiploic appendagitis from diverticulitis (LLQ) and appendicitis (RLQ)

Image Interpretation Pearls

SELECTED REFERENCES 1. 2. 3.

4. 5. 6.

7. 8. 9. 10.

11. 12. 13. 14. 15.

Menozzi G et al: Contrast-enhanced ultrasound appearance of primary epiploic appendagitis. J Ultrasound. 17(1):75-6, 2014 Shields AM et al: A twist in the tale: epiploic appendagitis mimicking acute appendicitis. BMJ Case Rep. 2014, 2014 Hwang JA et al: Differential diagnosis of left-sided abdominal pain: primary epiploic appendagitis vs colonic diverticulitis. World J Gastroenterol. 19(40):6842-8, 2013 Lee CC et al: Clinical challenges and images in GI. Epiploic appendagitis. Gastroenterology. 134(7):1829, 2196, 2008 Ng KS et al: CT features of primary epiploic appendagitis. Eur J Radiol. 2006 Pereira JM et al: CT and MR imaging of extrahepatic fatty masses of the abdomen and pelvis: techniques, diagnosis, differential diagnosis, and pitfalls. Radiographics. 25(1):69-85, 2005 Singh AK et al: Acute epiploic appendagitis and its mimics. Radiographics. 25(6):1521-34, 2005 Sandrasegaran K et al: Primary epiploic appendagitis: CT diagnosis. Emerg Radiol. 11(1):9-14, 2004 Singh AK et al: CT appearance of acute appendagitis. AJR Am J Roentgenol. 183(5):1303-7, 2004 Chowbey PK et al: Torsion of appendices epiploicae presenting as acute abdomen: laparoscopic diagnosis and therapy. Indian J Gastroenterol. 22(2):68-9, 2003 Ghosh BC et al: Primary epiploic appendagitis: diagnosis, management, and natural course of the disease. Mil Med. 168(4):346-7, 2003 van Breda Vriesman AC: The hyperattenuating ring sign. Radiology. 226(2):556-7, 2003 Chung SP et al: Primary epiploic appendagitis. Am J Emerg Med. 20(1):62, 2002 Hollerweger A et al: Primary epiploic appendagitis: sonographic findings with CT correlation. J Clin Ultrasound. 30(8):481-95, 2002 Legome EL et al: Epiploic appendagitis: the emergency department presentation. J Emerg Med. 22(1):9-13, 2002

Epiploic Appendagitis Colon

(Left) Axial CECT in a 63-yearold man presenting with LLQ pain and fever demonstrates an elongated fatty appendage adjacent to the descending colon. (Right) Axial CECT in the same patient illustrates pericolonic fat stranding .

(Left) Transverse ultrasound of the RLQ in a 19-year-old man presenting with RLQ pain demonstrates an echogenic appendage , surrounded by a hypoechoic rim. The lesion was tender and noncompressible. (Right) Axial CECT in the same patient illustrates an oval fatty appendage adjacent to the ascending colon with surrounding fat stranding , characteristic findings for epiploic appendagitis. Omental infarction may have a similar presentation but usually appears as a larger "ball of dirty fat."

(Left) In this somewhat obese patient, CT shows a small calcified lesion adjacent to the transverse colon, that represents a calcified, infarcted epiploic appendage. (Right) In the same case, similar calcified small loose bodies are identified in a dependent peritoneal recess and presumably represent infarcted appendages that have detached from the colon. Similar findings can result from "dropped" gallstones, but this patient had an intact gallbladder.

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Colon

Sigmoid Volvulus KEY FACTS

TERMINOLOGY • Torsion or twisting of sigmoid colon around its mesenteric axis

IMAGING • Location ○ Midline; directed toward RUQ or LUQ; elevation of hemidiaphragm • Diagnosis: Abdominal radiography, water-soluble contrast enema, CT ○ Coronal reformatted CT is especially useful in diagnosis ○ Abdominal radiographs: Supine, upright, prone, and decubitus views

CLINICAL ISSUES • Most common signs/symptoms ○ Acute or insidious onset ○ Abdominal pain (< 33%), vomiting, distension, obstipation • Treatment: Sigmoidoscopic decompression of obstruction ± stabilization via rectal tube insertion ○ Usually followed by surgical resection of sigmoid colon

PATHOLOGY

DIAGNOSTIC CHECKLIST

• Major predisposing factors ○ Diet: Fiber increase increased bulk of stool, elongation and dilatation of colon

• Rule out other causes of distal colonic obstruction • Dilated sigmoid colon in inverted "U" shape with absent haustra; "beaking," whirl sign, northern exposure sign

(Left) Supine film of the abdomen shows marked dilation of the sigmoid colon. The sigmoid is folded back upon itself, and the apposed walls of the redundant sigmoid colon form the "seam" of the football (or coffee bean) shape. The sigmoid extends into the upper abdomen above the transverse colon . (Right) Axial CECT in the same case shows the dilated sigmoid lumen with abrupt narrowing at its base .

(Left) Coronal reformatted CT in the same patient shows twisting and displacement of the base of the sigmoid colon and its mesentery . The dilated colonic segments upstream from the volvulus may be easier to distinguish on coronal sections. (Right) Another CT section in this case shows the whirl sign of twisted colon and vessels at the base of the sigmoid mesentery.

502

○ Chronic constipation and obtundation from medications gaseous distension • Comorbid disease: 30% with psychiatric disease, 13% are institutionalized at time of diagnosis

Sigmoid Volvulus

Definitions • Torsion or twisting of sigmoid colon around its mesenteric axis

IMAGING General Features • Best diagnostic clue ○ Dilated sigmoid colon with inverted "U" configuration and absent haustra • Location ○ Midline; directed toward RUQ or LUQ; elevation of hemidiaphragm

Radiographic Findings • Radiography ○ Sigmoid volvulus – Diagnostic in 75% of cases – Vertical dense white line: Apposed inner walls of sigmoid colon pointing toward pelvis – Closed loop obstruction: Segment of bowel obstructed at 2 points – Gas in proximal small intestine and colon; absence of gas in rectum – Absent rectal gas in spite of prone or decubitus views – Inverted "U" shape with absent haustra – Northern exposure sign: Dilated, twisted sigmoid colon projects above transverse colon on supine radiograph – Apex above T10 vertebra and under left hemidiaphragm; directed toward right shoulder ○ Compound volvulus – Dilated sigmoid loop in mid abdomen extending to RLQ with distended small bowel – Medially deviated distal left colon

Fluoroscopic Findings • Water-soluble contrast enema ○ Can use low-pressure barium enema without balloon inflation ○ "Beaking": Smooth, tapered narrowing or point of torsion at rectosigmoid junction ○ Mucosal folds often show corkscrew pattern at point of torsion ○ Shouldering: Localized wall thickening at site of twist (in chronic or recurrent volvulus)

CT Findings • CECT ○ "Beaking": Progressive tapering of afferent and efferent limbs leading into twist ○ Whirl sign: Tightly twisted mesentery and bowel near base of volvulus ○ Compound volvulus: Medial deviation of distal left colon with pointed appearance of medial border

Imaging Recommendations • Best imaging tool ○ Abdominal radiography, water-soluble contrast enema, CT

Colon

– Supine, upright, prone, and decubitus views of abdomen – Coronal reformatted CT is especially useful in diagnosis

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Acute Ileus • • • •

Postop, medication, post-traumatic injury, ischemia Dilated large and small bowel with no transition point Air-fluid levels without peristalsis No colonic obstruction

Functional Megacolon • Gross constipation without organic cause • Markedly dilated, ahaustral, air- or stool-filled colon • Ogilvie syndrome: Nonobstructive dilation of colon

Toxic Megacolon • Dilated ahaustral transverse colon in patient with known ulcerative or infectious colitis • "Thumbprinting" due to edematous mucosa • Mucosal surface is ulcerated or sloughed

Distal Colon Obstruction • Change in stool caliber over several months • Gas-filled intestinal loops proximal to obstruction; no distal gas • Abrupt transition at site of obstruction • Malignancy ○ Most common cause of colonic obstruction (55%) ○ Insidious onset ○ Weakness, weight loss, anorexia, rectal bleeding ○ "Apple core" configuration, mucosal destruction ○ Positive fecal occult blood test highly suggestive of colon cancer • Stricture secondary to diverticulitis ○ 2nd most common cause of colonic obstruction (12%) ○ History of recurrent diverticulitis ○ Other diverticula present ○ Signs of diverticulitis (e.g., infiltrated mesocolic fat, extraluminal gas or fluid)

PATHOLOGY General Features • Etiology ○ Major predisposing factors – Diet: Fiber increase increased bulk of stool, elongation and dilatation of colon – Chronic constipation and obtundation from medications gaseous distension ○ Compound volvulus (ileosigmoid knot) – Hyperactive ileum winding around narrow pedicle of passive sigmoid colon ○ Etiology in children – Malrotation and other mesenteric attachment abnormalities – Constipation (mental retardation, Hirschsprung disease, cystic fibrosis, aerophagia) • Associated abnormalities 503

Colon

Sigmoid Volvulus ○ Comorbid disease: 30% with psychiatric disease, 13% are institutionalized at time of diagnosis

Gross Pathologic & Surgical Features • Twisted narrow segment with markedly dilated sigmoid loop

DIAGNOSTIC CHECKLIST

Microscopic Features

Consider

• Localized thickening of mucosal folds; ischemic and necrotic changes

• Acute abdomen; rule out other causes of obstruction

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute or insidious onset ○ Abdominal pain (< 33%), vomiting, distension, obstipation ○ Compound volvulus – Rapid deterioration (more than with other colonic volvulus types) – Pain disproportionate to physical findings; absolute constipation ○ Diagnosis: Radiography is definitive in 75% of cases

Demographics • Age ○ 60-80 years • Epidemiology ○ 3rd most common cause of colonic obstruction (10%) ○ 60-75% of colonic volvulus cases involve sigmoid colon ○ Causes 1-2% of intestinal obstructions in USA ○ Increased incidence in elderly men and residents of nursing homes &/or mental hospitals (constipation and obtundation) ○ Significant increase in South America and Africa (increased fiber in diet)

Natural History & Prognosis • Complications ○ Closed loop obstruction strangulation ○ Ischemia, necrosis (15-20%), and perforation ○ Ileosigmoid knot strangulation and gangrene of small bowel within hours • Prognosis ○ Uncomplicated: Good ○ Complicated: Poor ○ 40-50% recurrence after nonoperative reduction ○ Degree of rotation relative to chance of nonsurgical decompression: 180° (35%), 360° (50%), 540° (10%) – Twist > 360° does not resolve spontaneously ○ 3% recurrence after nonoperative and operative reduction

Treatment • Nonoperative ○ Sigmoidoscopic decompression of obstruction ± stabilization via rectal tube insertion ○ 70-80% success rate • Nonoperative and operative ○ Decompression, mechanical cleansing, and elective sigmoid resection • Complicated cases 504

○ Surgical emergency; colonic resection • Follow-up ○ Water-soluble contrast enema to rule out underlying colon cancer

Image Interpretation Pearls • Dilated sigmoid colon in inverted "U" shape with absent haustra; "beaking," whirl sign, northern exposure sign

SELECTED REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Maddah G et al: Management of sigmoid volvulus: options and prognosis. J Coll Physicians Surg Pak. 24(1):13-7, 2014 Selçuk Atamanalp S: Treatment for ileosigmoid knotting: a single-center experience of 74 patients. Tech Coloproctol. 18(3):233-7, 2014 Meyer F et al: Unusual "twister"-like appearance of a sigmoid volvulus on computed tomography. Endoscopy. 39 Suppl 1:E295, 2007 Tiah L et al: Sigmoid volvulus: diagnostic twists and turns. Eur J Emerg Med. 13(2):84-7, 2006 Agaoglu N et al: Surgical treatment of the sigmoid volvulus. Acta Chir Belg. 105(4):365-8, 2005 Chandrasekaran TV et al: Minimally invasive stapled surgical approach to the management of sigmoid volvulus. Ann R Coll Surg Engl. 87(5):381-2, 2005 Matsumoto S et al: Computed tomographic imaging of abdominal volvulus: pictorial essay. Can Assoc Radiol J. 55(5):297-303, 2004 Chiu HH et al: Recurrent sigmoid volvulus. Gastrointest Endosc. 56(3):419-20, 2002 Kuzu MA et al: Emergent resection for acute sigmoid volvulus: results of 106 consecutive cases. Dis Colon Rectum. 45(8):1085-90, 2002 Chirdan LB et al: Sigmoid volvulus and ileosigmoid knotting in children. Pediatr Surg Int. 17(8):636-7, 2001 Moore CJ et al: CT of cecal volvulus: unraveling the image. AJR Am J Roentgenol. 177(1):95-8, 2001 Daniels IR et al: Recurrent sigmoid volvulus treated by percutaneous endoscopic colostomy. Br J Surg. 87(10):1419, 2000 Dulger M et al: Management of sigmoid colon volvulus. Hepatogastroenterology. 47(35):1280-3, 2000 Lee SH et al: The ileosigmoid knot: CT findings. AJR Am J Roentgenol. 174(3):685-7, 2000 Madiba TE et al: The management of sigmoid volvulus. J R Coll Surg Edinb. 45(2):74-80, 2000 Chung YF et al: Minimizing recurrence after sigmoid volvulus. Br J Surg. 86(2):231-3, 1999 Javors BR et al: The northern exposure sign: a newly described finding in sigmoid volvulus. AJR Am J Roentgenol. 173(3):571-4, 1999 Choi D et al: Endoscopic sigmoidopexy: a safer way to treat sigmoid volvulus? J R Coll Surg Edinb. 43(1):64, 1998 Catalano O: Computed tomographic appearance of sigmoid volvulus. Abdom Imaging. 21(4):314-7, 1996 Frizelle FA et al: Colonic volvulus. Adv Surg. 29:131-9, 1996 Forde KA: Therapeutic colonoscopy. World J Surg. 16(6):1048-53, 1992 Gibney EJ: Volvulus of the sigmoid colon. Surg Gynecol Obstet. 173(3):24355, 1991

Sigmoid Volvulus Colon

(Left) Axial CECT in a 47-yearold man presenting with a 6day history of abdominal distension and pain, constipation, and absence of flatus shows the sigmoid volvulus evident in the LLQ with the beaked appearance of the descending loop of the twisted sigmoid colon. (Right) Coronal CECT in the same patient illustrates a swirled appearance of the mesenteric pedicle at the site of the sigmoid volvulus , characteristic findings in this setting.

(Left) Radiograph in a 65-yearold man presenting with abdominal pain and distention demonstrates a dilated redundant sigmoid colon appearing as an inverted "U" loop arising from the pelvis in this typical presentation of a sigmoid volvulus. (Right) Supine frontal image from a contrast enema in the same patient demonstrates luminal tapering at the site of stenosis, a.k.a. the bird's beak sign . This configuration is pathognomonic for sigmoid volvulus.

(Left) Supine digital scout radiograph in an 89-year-old man who is a long-time resident of a nursing home, presenting with a 2-day history of severe abdominal pain and marked abdominal distension, reveals marked dilation of the sigmoid colon as well as the ascending and descending colon . Note the apposed walls of the sigmoid colon. (Right) Axial CECT in the same patient illustrates the bird's beak sign from the volvulus obstructing the massively dilated sigmoid colon .

505

Colon

Cecal Volvulus KEY FACTS

TERMINOLOGY

• Best imaging test: CT in axial and coronal planes

• Cecal volvulus: Rotational twist of right colon on its axis, resulting in progressive distention and potential ischemia • Cecal bascule ○ Cecum is distended and lumen narrowed by medial folding and displacement, without a twist

TOP DIFFERENTIAL DIAGNOSES

IMAGING • Radiography: Dilated, air-filled cecum in LUQ or abdominal midline ○ Single, long air-fluid level within cecum (upright or decubitus film) ○ Moderately distended gas or fluid-filled small bowel, little gas in distal colon ○ Markedly dilated cecum that appears upside down and backward with ileocecal valve directed laterally • Additional CT signs ○ Whirl sign: Tightly twisted colonic wall and ileocolic mesenteric vessels

(Left) Graphic shows a twist (volvulus) of the ascending colon, obstructing the lumen and blood supply. The cecum on the mesentery is dilated and displaced toward the left upper quadrant (LUQ). (Right) Supine radiograph shows a gas-distended segment of bowel (cecum) within the mid abdomen. The base of the cecum is directed toward the upper quadrant, and the ileocecal valve is directed laterally. Small bowel is gasdistended, whereas the left colon is relatively collapsed.

(Left) Axial CT in the same case shows a markedly distended cecum and a twisted ("whirled") ileocolic mesentery within the right lower quadrant. (Right) Coronal reformatted CT in the same case shows the markedly distended midline cecum . The cecum is upside down and backward, with the ileocecal valve pointed laterally. Coronal-reformatted CT is usually the most definitive study to show the characteristic features of cecal volvulus.

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• • • •

Sigmoid volvulus Acute ileus Distal colon obstruction Ogilvie syndrome

PATHOLOGY • Embryology/anatomy ○ Right colon is incompletely fused to posterior parietal peritoneum • There are many causes of colonic distention, but ligamentous laxity is necessary for cecal volvulus to occur

CLINICAL ISSUES • Accounts for 1/3 of colonic volvulus cases • Complications: Ischemia, necrosis, perforation • Treatment: Colonoscopy to reduce volvulus, surgery to prevent recurrence

Cecal Volvulus

Synonyms • Volvulus of cecum and part of ascending colon

Ogilvie Syndrome • Colonic pseudoobstruction without mechanical cause

PATHOLOGY

Definitions

General Features

• Rotational twist of right colon on its axis, resulting in progressive distention and potential ischemia • Cecal bascule ○ Cecum is distended and lumen narrowed by medial folding and displacement, without twist

• Etiology ○ Embryology/anatomy – Right colon is incompletely fused to posterior parietal peritoneum ○ Postpartum ligamentous laxity, mobile cecum ○ Postoperative changes resulting in loss of peritoneal attachments ○ Chronic constipation, laxative use ○ Colon distension (pseudoobstruction, distal tumor, endoscopy, enema, postoperative ileus) – There are many causes of colonic distention, but ligamentous laxity is necessary for cecal volvulus to occur • Associated abnormalities ○ Malrotation, long mesentery

IMAGING General Features • Best diagnostic clue ○ Markedly dilated cecum that appears upside down and backward with ileocecal valve directed laterally

Radiographic Findings • Radiography ○ Dilated, air-filled cecum in left upper quadrant (LUQ) or abdominal midline ○ Single, long air-fluid level within the cecum (on upright or decubitus film) ○ Laterally directed ileocecal valve ○ Moderately distended gas or fluid-filled small bowel, little gas in distal colon

Fluoroscopic Findings • Water-soluble contrast enema: Point of torsion at mid ascending colon ("beaking")

CT Findings • CECT ○ Cecum and some portion of ascending colon are markedly dilated with air-fluid level ○ Cecum appears upside down and backward ○ Ileocecal valve points laterally ○ Whirl sign: Tightly twisted wall of ascending colon and ileocolic mesenteric vessels ○ Small bowel is dilated – Transverse and descending colon are collapsed

Gross Pathologic & Surgical Features • Twisted, markedly dilated segment of right colon

Microscopic Features • Localized mucosal ischemic and necrotic changes

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute or insidious onset of abdominal pain, distension, vomiting

Demographics • Epidemiology ○ Accounts for 1/3 of colonic volvulus cases ○ Accounts for 2-3% of colonic obstructions

Natural History & Prognosis • Complications: Ischemia, necrosis, perforation of cecum • Prognosis: Good if uncomplicated, poor if complicated

Imaging Recommendations

Treatment

• Best imaging tool ○ CT in axial and coronal planes

• Colonoscopy to reduce volvulus, surgery to prevent recurrence ○ Surgery (cecopexy, cecostomy, resection)

DIFFERENTIAL DIAGNOSIS Sigmoid Volvulus • Dilated, ahaustral sigmoid loop; inverted "U" configuration • Apposed walls of sigmoid loop form "seam" of coffee bean shape of volvulus

Acute Ileus • Dilated colon to rectum with preserved haustral pattern

Distal Colon Obstruction • Gas- and stool-filled colon proximal to obstruction

Toxic Megacolon • Markedly dilated, ahaustral transverse colon

Colon

TERMINOLOGY

DIAGNOSTIC CHECKLIST Consider • Rule out ileus, Ogilvie syndrome

Image Interpretation Pearls • Massively dilated cecum that appears upside down and backward, with ileocecal valve directed laterally

SELECTED REFERENCES 1. 2.

Halabi WJ et al: Colonic volvulus in the United States: trends, outcomes, and predictors of mortality. Ann Surg. 259(2):293-301, 2014 Heller MT et al: MDCT of acute cecal conditions. Emerg Radiol. 21(1):75-82, 2014

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Colon

Colonic Ileus and Ogilvie Syndrome KEY FACTS

IMAGING • Dilated colon without obstructive lesion, associated with adynamic ileus and abdominal distention • Proximal colon (cecum) dilates more than rest of colon • Plain radiographs and CT for initial diagnosis • Consider contrast enema ○ Can be therapeutic in some cases • Colonic ileus: Transitional zone at splenic flexure ○ Descending colon is often less distended than more proximal colon

TOP DIFFERENTIAL DIAGNOSES • Cecal and sigmoid volvulus • Colon carcinoma • Diverticulitis ○ Pericolonic inflammation, mesenteric hyperemia • Ischemic colitis ○ Common sites: Splenic flexure > sigmoid colon • Hirschsprung disease

(Left) Axial NECT shows disproportionate dilation of the cecum and ascending colon in comparison with the normal-appearing descending colon and small bowel. There was no evidence of a colonic obstruction or volvulus. (Right) Supine radiograph in a patient with postoperative colonic ileus shows distention of the entire colon but minimal gas within the small bowel. Skin clips are evident in the right lower quadrant from a recent renal transplant procedure.

(Left) Supine radiograph of a young women, who recently had open heart surgery and now has a distended abdomen, shows dilation of a mobile cecum to 10 cm, and slightly less dilation of the transverse colon. A feeding tube marks the stomach. (Right) Repeat film in the same case the following morning shows progressive dilation of the cecum (to 14 cm) and transverse colon. Following a call to the referring physicians, the colon was decompressed using IV neostigmine and colonic intubation and suction.

508

• Toxic megacolon ○ Very ill patient with active colitis • Infectious colitis ○ CT: Mucosal hyperenhancement, submucosal edema • Fecal impaction and stercoral ulceration

CLINICAL ISSUES • May progress to ischemia and perforation • Treatment: Supportive therapy, intravenous neostigmine • Intervention: Endoscopic decompression ○ Percutaneous cecostomy ○ Surgical cecostomy or cecectomy

DIAGNOSTIC CHECKLIST • Cecal diameter > 12 cm (on plain supine radiographs) is considered at risk for perforation • Colon diameter will always measure less on CT ○ Diameter > 8 cm is significant dilation

Colonic Ileus and Ogilvie Syndrome

Synonyms • Ogilvie syndrome, colonic pseudoobstruction, pseudomegacolon, adult megacolon, adynamic ileus, functional obstruction, idiopathic large bowel obstruction

Definitions • Dilation of colon with obstructive symptoms without mechanical obstruction in acute or chronic setting ○ Acute: Reversible, occurring with severe medical illness and major surgeries ○ Chronic: Constipation, no etiology for ileus, and repeated obstructive symptoms

IMAGING General Features • Best diagnostic clue ○ Dilated colon without obstructive lesion, associated with adynamic ileus and abdominal distention • Location ○ Proximal colon (cecum) > remainder of colon – Law of Laplace: Segment of colon with greatest normal diameter (cecum) will be the segment most easily dilated from obstruction or ileus • Size ○ Cecum may reach 10-20 cm • Morphology ○ Normal to thin colonic wall; massive dilation of lumen

Imaging Recommendations • Best imaging tool ○ Computed tomography (CT): Differentiates mechanical obstruction from pseudo-obstruction – No risk of peritoneal contrast extravasation – Can identify obstructing lesions, primary colonic pathology (e.g., colitis, volvulus), extracolonic pathology that might cause colonic dilation (e.g., peritoneal carcinomatosis; pancreatitis) • Protocol advice ○ Plain radiographs and CT for initial diagnosis ○ Consider contrast enema – Therapeutic in some cases – Hypertonic iodinated contrast medium draws fluid into colon, stimulates evacuation – Danger of perforation if colon is severely inflamed (e.g., toxic megacolon) or ischemic

CT Findings • With IV contrast: Sensitivity and specificity of 91% ○ Accurate depiction of luminal distention ○ Characteristic transitional zone at splenic flexure – Descending colon is often less distended than more proximal colon – Do not mistake for colonic obstruction □ Look for intrinsic or extrinsic process at transition point to document obstruction □ e.g., colon carcinoma or acute pancreatitis ○ Detects inflammation of mucosa (if present) – Adjacent fat stranding indicates inflammation – Submucosal edema; low-density "halo" ○ Detects ischemic changes – Splenic flexure is common site for ischemic colitis – Wall thickening, submucosal edema, necrosis, intramural gas • Yields information about location and cause of bowel obstruction (if present)

Colon

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Cecal or Sigmoid Volvulus • Dilated colon on long, twisted mesentery • Result in progressive dilation of colon with risk of ischemia and perforation • Twist and obstruction of lumen often evident on contrast enema or CT

Colon Carcinoma • CT shows short segment wall thickening and luminal narrowing at tumor • Colon often distended proximal to tumor • Regional mesenteric lymph node and liver metastases often present at diagnosis • Most common cause of colonic obstruction in adults

Diverticulitis • May narrow lumen, thicken wall (longer segment involvement), cause obstruction • Pericolonic inflammation, mesenteric hyperemia, ± gas or abscess

Ischemic Colitis • Etiologies: Hypoperfusion > arterial or venous occlusion • Common sites of involvement: Splenic flexure > sigmoid colon • Wall thickening ± gas in wall

Radiographic Findings

Hirschsprung Disease

• Radiography ○ Plain abdominal radiography – Dilation of cecum, ascending colon, and transverse colon – Free air indicates perforation □ Usually large amount of peritoneal gas with colonic perforation • Contrast enema (water soluble) ○ Sensitivity (96%), specificity (98%) for distinguishing obstruction from pseudo-obstruction ○ Rules out obstructive lesions ○ Contrast extravasation if perforation has occurred

• Barium enema: Transition zone, irregular contractions, mucosal irregularity, and delayed evacuation of contrast material ○ Transition zone: Dilated, normal colon above and narrowed, aganglionic colon below

Toxic Megacolon • Abdominal films and CT: Dilation of transverse colon > ascending colon and descending colon ○ "Thumbprinting": Colonic mucosa coarse and irregular due to edema ○ Loss of haustra in dilated bowel 509

Colon

Colonic Ileus and Ogilvie Syndrome ○ Pseudopolyps or inflammatory polyps ○ History is key to diagnosis – Very ill patient with history of inflammatory bowel disease or infectious colitis

Infectious Colitis • CT: Mucosal hyperenhancement, submucosal edema, thickened walls, accordion sign, target sign, pericolonic stranding, and ascites

Fecal Impaction and Stercoral Ulceration • Abdominal film: Rectosigmoid colon distended with stool • Pneumatosis, perirectal infiltration raise concern for perforation

PATHOLOGY General Features • Etiology ○ Electrolyte or metabolic disturbances ○ Operative trauma (23%), nonoperative trauma (11%), infections (10%), cardiac disease (10-18%) ○ Reduced number of ganglion cells ○ Parasympathetic dysfunction (drug-induced, psychogenic, acquired, etc.) ○ Intramural ganglion damage (documented in some cases of drug-induced colonic ileus)

Microscopic Features • Atrophic changes and decreased numbers of intramural ganglions in some patients

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal distension, pain, nausea &/or vomiting, failure to pass flatus and stool • Other signs/symptoms ○ May progress to ischemia (due to impaired venous drainage with increased intraluminal pressure) – May lead to colonic perforation □ Spill of fecal material into peritoneal cavity, peritonitis □ High morbidity and mortality (25-30%); even higher if preceded by colonic ischemia (40-50%)

Demographics • Age ○ Highest prevalence observed in late middle age (~ 60 years) • Gender ○ M>F • Epidemiology ○ Orthopedic surgical procedures (1% of patients develop colonic ileus) ○ Spine surgery and other causes of severe pain, especially with subsequent immobilization at bedrest ○ Burn patients (~ 1%) ○ Chronic intestinal pseudoobstruction – A serious neuropathic or musculopathic disorder that results in chronic and massive distention and malfunction of bowel 510

– Has more insidious onset, longer duration, and is less responsive to treatment

Natural History & Prognosis • Delayed diagnosis and ineffective treatment increase morbidity and mortality

Treatment • Supportive therapy, intravenous neostigmine • Endoscopic decompression ○ Place suction catheter into transverse colon to remove intraluminal gas ○ Rectal tube alone is less likely to be effective • Percutaneous cecostomy ○ Place "pigtail" catheter into cecum and suction gas from lumen • Surgical cecostomy ○ ± cecopexy (fixing cecum to retroperitoneum to prevent volvulus) ○ ± cecal resection (usually if cecum is ischemic or perforated) • Chronic intestinal pseudo-obstruction ○ No effective medical therapy ○ Subtotal colectomy gives symptomatic relief to most patients with chronic form of colonic pseudoobstruction

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Cecal diameter > 12 cm (on plain supine radiographs) is considered worrisome for perforation ○ However, many patients with chronic constipation or ileus have greater luminal distention without perforation • Colonic diameter will always measure less on CT than on plain films ○ Diameter of > 8 cm on CT is significant dilation

SELECTED REFERENCES 1. 2. 3. 4. 5. 6. 7.

8.

9.

Gabbard SL et al: Chronic intestinal pseudo-obstruction. Nutr Clin Pract. 28(3):307-16, 2013 Doorly MG et al: Pathogenesis and clinical and economic consequences of postoperative ileus. Surg Clin North Am. 92(2):259-72, viii, 2012 Elsner JL et al: Intravenous neostigmine for postoperative acute colonic pseudo-obstruction. Ann Pharmacother. 46(3):430-5, 2012 Tsirline VB et al: Colonoscopy is superior to neostigmine in the treatment of Ogilvie's syndrome. Am J Surg. 204(6):849-55; discussion 855, 2012 De Giorgio R et al: Acute colonic pseudo-obstruction. Br J Surg. 96(3):229-39, 2009 Choi JS et al: Colonic pseudoobstruction: CT findings. AJR Am J Roentgenol. 190(6):1521-6, 2008 Grassi R et al: Ogilvie's syndrome (acute colonic pseudo-obstruction): review of the literature and report of 6 additional cases. Radiol Med. 109(4):370-5, 2005 Stieger DS et al: Acute colonic pseudoobstruction (Ogilvie's syndrome) in two patients receiving high dose clonidine for delirium tremens. Intensive Care Med. 23(7):780-2, 1997 Vráblik V et al: [Pseudoobstruction syndrome of the large intestine (endoscopic therapy).] Vnitr Lek. 36(10):1002-4, 1990

Colonic Ileus and Ogilvie Syndrome Colon

(Left) Supine radiograph of a 63-year-old woman who recently had surgical repair of a ventral shows diffuse dilation of the colon without definite dilation of the small bowel. (Right) CT in the same case shows an open wound from the hernia repair. The colon is diffusely dilated, while the small intestine is normal in caliber. The colonic distention persisted all the way to the rectum, although the descending colon is less dilated, a common finding in ileus that should not be confused with an obstructing lesion.

(Left) This 42-year-old woman has cardiomyopathy treated with a left ventricular assist device . Complaints of abdominal pain and distention led to this supine film showing massive distention of the colon. The cecum was 11 cm and the transverse colon 8 cm in diameter. On CT, however, the cecum measured 8 cm and the transverse colon measured 6 cm in diameter. (Right) In the same case, endoscopic placement of a colonic tube allowed decompression and relief of symptoms.

(Left) Anteroposterior supine radiograph shows a dilated gas-filled segment of colon in the upper abdomen, with its tip pointing to the left upper quadrant. (Right) Anteroposterior radiograph in the same patient shows gas within the liver in a peripheral branching pattern, consistent with portal venous gas. At surgery, the cecum was twisted on its mesentery (cecal volvulus) with ischemic necrosis of its wall.

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Fecal Impaction and Stercoral Ulceration KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Hardened and impacted mass of feces that cannot be passed and obstructs colonic lumen • Stercoral ulceration ○ Pressure necrosis of bowel lumen (rectum or sigmoid) by fecal mass

• Colon carcinoma ○ Thickens wall of colon, narrows lumen • Villous adenoma, colon ○ Bulky but soft intraluminal and mural mass

IMAGING • CECT to evaluate for perirectal and intraperitoneal complications ○ Fecaloma: Entirely intraluminal mass ○ Calcification or high-density matter in or around fecal mass ○ Laminated, radiopaque mass of feces ○ Focal thickening of bowel wall and pericolonic fat stranding (suggests stercoral colitis) ○ Pneumatosis, free air (confirms perforation)

(Left) CT in an 85-year-old woman with chronic constipation and acute abdominal pain shows free intraperitoneal air . (Right) Sagittal reformatted CT section in the same case shows massive fecal distention of the rectosigmoid colon with disruption of the anterior wall of the sigmoid colon.

(Left) Axial CECT in an 80year-old woman presenting with chronic constipation and acute abdominal pain shows free intraperitoneal gas and massive distention of the rectum and left colon with gas and impacted feces . (Right) Axial CECT in the same patient shows the rectum massively distended with high density feces . Infiltration of the perirectal fat suggests stercoral ulceration, confirmed at surgery. The rectal perforation by stercoral colitis was fatal in this case.

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PATHOLOGY • Stercoral colitis: Focal inflammatory colitis due to pressure on bowel wall by fecal mass • Stercoral ulcer: Pressure necrosis of bowel mucosa on antimesenteric aspect of bowel ○ Perforation: Associated with 35% mortality

CLINICAL ISSUES • Can be life-threatening and is underdiagnosed • Usually seen in elderly, debilitated patients ○ Or patients on anticholinergic or narcotic medications • Requires urgent catharsis, enema, manual disimpaction • Emergency surgery for perforation

Rectal Prolapse and Intussusception Colon

KEY FACTS

TERMINOLOGY

IMAGING

• Partial prolapse ○ Rectal mucosa protrudes no more than 1 inch below anus (shown on defecography) • External (complete) prolapse (procidentia) ○ All layers of rectum protrude through anus ○ Diagnosis made on physical exam or defecography • Rectosigmoid (internal) intussusception ○ Proximal rectal ± sigmoid mucosa telescopes into distal rectum; rarely through anus – Often "pinches off" base of anterior rectocele – Contributes to sensation of incomplete evacuation ○ Diagnosed on defecography or MR • Rectal ulcer syndrome ○ Traumatic or ischemic ulceration of rectal mucosa associated with disordered evacuation ○ Diagnosed on barium enema or sigmoidoscopy ○ 95% of affected patients have internal intussusception

• Complex disorders of muscles, fascia, and supporting structures of pelvic floor ○ Involves posterior pelvic compartment • MR for complete and direct visualization of pelvic organs and supporting structures of all 3 compartments • Barium evacuation proctography for rectal disorders

PATHOLOGY • Pelvic floor disorders often overlap ○ e.g., urinary and fecal incontinence; prolapse of bladder and rectum

CLINICAL ISSUES • > 90% of adult cases are women ○ Some degree of pelvic floor weakening is present in > 50% of women over age 50

(Left) Graphic shows partial prolapse of rectal mucosa about 1 inch below the anus. Insert shows external (complete) rectal prolapse (procidentia) with herniation of all layers of the rectal wall. (Right) Film from defecography shows downward intussusception of the rectal mucosa, pinching of the neck of a large anterior rectocele . Note the low position of the rectum and anus relative to the ischial tuberosities .

(Left) Lateral spot film from a defecography study shows downward intussusception of rectal mucosa into the lower rectum, pinching off an anterior rectocele . (Right) In the same case a few seconds later, the rectum has herniated completely through the anus and is seen as a barium-coated mass outside the anus. This is called external (complete) prolapse or procidentia.

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Colon

Colorectal Trauma KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Blunt or penetrating injury to rectum or colon

• Pneumoperitoneum from other causes • Nontraumatic bowel wall thickening

IMAGING • Transverse and descending colon are most common sites for blunt traumatic injury ○ Rectum is most common site for penetrating injury • Best diagnostic clue ○ Colonic wall thickening with adjacent mesenteric hemorrhage or ectopic gas • Best imaging tool: CECT with multiplanar reformations ○ Rectal and intravenous contrast for penetrating injuries • CT signs ○ Discontinuity or thickening of colonic wall ○ Pneumoperitoneum, pericolonic fluid or feces ○ Extravasated blood is nearly isodense to opacified blood vessels ○ Extravasated endoluminal contrast medium = perforation of colon

(Left) Axial CECT in a 57-yearold man injured in a highspeed motor vehicle accident (MVA) shows multiple segments of thick-walled small intestine with infiltration of the adjacent mesentery. Higher than water density fluid is present within the mesentery and peritoneal recesses. (Right) Axial CECT in the same patient shows more small bowel wall thickening , free intraperitoneal gas , and active bleeding from the descending colon.

(Left) Axial CECT in the same patient shows more bubbles of free air , sentinel clot and active bleeding adjacent to the descending colon. Also note the vertebral (Chance) fracture . At surgery there were several lacerations of small bowel, and the descending colon had a "degloving" injury with active bleeding. (Right) Axial CECT in the same patient shows free air , bowel wall thickening , mesenteric infiltration, and a seat belt contusion of the abdominal wall .

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PATHOLOGY • Associated abnormalities ○ Injuries of small intestine, mesentery, solid viscera ○ Pelvic fractures associated with rectal injuries ○ "Chance" (transverse) fracture of the vertebrae

CLINICAL ISSUES • Other signs/symptoms ○ Abdominal wall contusion from seat belt injury ○ Perineal hematoma in rectal injury

DIAGNOSTIC CHECKLIST • Look for extravasation of vascular and endoluminal contrast media • Look for ectopic gas with wide windows on CT

Colorectal Trauma

Definitions • Blunt or penetrating injury to rectum or colon

IMAGING General Features • Best diagnostic clue ○ Colonic wall thickening with adjacent mesenteric hemorrhage or ectopic gas • Location ○ Transverse and descending colon are most common sites for blunt traumatic injury ○ Rectum is most common for penetrating injury – Especially due to insertion of foreign bodies

Gross Pathologic & Surgical Features • Intramural hematoma • Hematoma within sigmoid or transverse mesocolon • Serosal tears ○ "Degloving" injury: Serosa is avulsed from colonic surface ○ Results in ischemic injury of colon if not recognized and repaired at surgery

CLINICAL ISSUES Presentation • Other signs/symptoms ○ Abdominal wall contusion from seat belt injury ○ Perineal hematoma in rectal injury

Imaging Recommendations

Demographics

• Best imaging tool ○ CECT with multiplanar reformations • Protocol advice ○ Rectal, oral, and intravenous contrast for penetrating injuries to flank

• Epidemiology ○ 5% of blunt trauma patients have bowel or mesenteric injuries ○ Colon is 2nd most common organ injured with penetrating trauma

CT Findings • • • •

Discontinuity or thickening of colonic wall Pneumoperitoneum, pericolonic fluid or feces Mesenteric stranding, hemoperitoneum Active arterial extravasation from colonic vessels ○ Extravasated blood is nearly isodense to vessels • Extravasation of contrast material inserted via enema ○ Indicates perforation of rectum or colon

DIFFERENTIAL DIAGNOSIS Pneumoperitoneum From Other Causes • Pneumomediastinum, pneumothorax, recent peritoneal lavage, or prior laparotomy

Nontraumatic Bowel Wall Thickening • Colitis, inflammatory bowel disease • Intramural hemorrhage due to excessive anticoagulation or thrombocytopenia

PATHOLOGY

Colon

○ "Chance" (transverse) fractures of spine

TERMINOLOGY

Natural History & Prognosis • Overall mortality: 10% • Mortality 50% for missed rectal perforation • Vascular injury to colonic mesentery may result in delayed rupture

Treatment • Usually resection of injured colon with diverting colostomy • Primary repair of damaged segment if deemed feasible at surgery

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Look for ○ Abdominal wall contusion as indirect sign of seat belt injury to colon ○ Ectopic gas with wide windows on CT ○ Active bleeding with high-attenuation focus isodense to adjacent vessels ○ Colorectal perforation with extraluminal extravasation of contrast medium inserted via enema

General Features • Etiology ○ Depth of laceration varies from serosal tear to fullthickness laceration ○ Seat belt may impale colon between anterior abdominal wall and vertebral column, resulting in colonic injury ○ Pelvic fractures may result in serosal tear from bone fragments ○ Insertion of foreign objects into rectum may result in mucosal or full-thickness injuries – Colonoscopy results in colonic perforation in < 1% of procedures • Associated abnormalities ○ Small bowel and mesenteric injuries ○ Other solid organ injuries – Laceration of liver, kidney, spleen, &/or pancreas ○ Pelvic fractures associated with rectal injuries

SELECTED REFERENCES 1. 2. 3. 4. 5.

Bortolin M et al: Primary repair or fecal diversion for colorectal injuries after blast: a medical review. Prehosp Disaster Med. 29(3):317-9, 2014 Daly B et al: Complications of optical colonoscopy: CT findings. Radiol Clin North Am. 52(5):1087-99, 2014 Watson JD et al: Risk factors for colostomy in military colorectal trauma: a review of 867 patients. Surgery. 155(6):1052-61, 2014 Bondia JM et al: Imaging colorectal trauma using 64-MDCT technology. Emerg Radiol. Epub ahead of print, 2009 Anderson SW et al: Anorectal trauma: the use of computed tomography scan in diagnosis. Semin Ultrasound CT MR. 29(6):472-82, 2008

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Colonic Polyps KEY FACTS

TERMINOLOGY • Focal, space-occupying masses that arise from colonic mucosa and protrude into colonic lumen

IMAGING • CT "virtual" colonography ○ Best radiographic alternative to optical colonoscopy ○ Proper technique critical, including utilization of colon cleansing agent, stool "tagging" agent, electronic CO₂ insufflator, and separate supine and prone acquisitions ○ Polyps appear as small or large, sessile or pedunculated, lesions extending from colon wall ○ Polyps measuring 5 mm generally not reported ○ Polyps measuring 1 cm referred for polypectomy • Air- (double) contrast barium enema ○ Sessile polyps – Dependent wall: Radiolucent filling defect – Nondependent wall: Ring shadow with barium-coated white rim

(Left) Graphic shows a tubulovillous adenoma on a long stalk and a small sessile polyp . (Right) Singlecontrast barium enema demonstrates a tubulovillous adenoma with a large head and a long stalk . A small sessile polyp is also seen.

(Left) Air-contrast barium enema shows a large sessile polyp in the cecum, having the typical appearance of a villous adenoma, with cauliflower-like surface irregularity. (Right) Aircontrast barium enema shows a small polyp on a short stalk . The outer rim of the "Mexican hat" is the head of the polyp, while the inner ring is the stalk.

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– Bowler hat sign: Brim and dome of hat represents base and head of polyp, with dome of hat pointing towards lumen of bowel (en face view) ○ Pedunculated polyps – Mexican hat sign: Pair of concentric rings with outer and inner rings representing head and stalk of polyp ○ "Carpet" lesion: Tiny, coalescent nodules and plaques create a finely nodular or reticular pattern

PATHOLOGY • Neoplastic polyps: Adenomatous (tubular, tubulovillous, and villous) • Nonneoplastic polyps: Hyperplastic, hamartomatous, and inflammatory • All adenomatous polyps contain foci of dysplasia and represent potential precursors to colon carcinoma

CLINICAL ISSUES • Any polyp 1 cm on barium enema or CT colonography should undergo colonoscopic polypectomy

Colonic Polyps

Definitions • Focal, space-occupying masses that arise from colonic mucosa and protrude into colonic lumen

IMAGING General Features • Best diagnostic clue ○ Smooth-surfaced intraluminal small mass on CT colonoscopy or barium enema • Location ○ Cecum (4%), ascending colon (6%), hepatic flexure (4%), transverse (2%), splenic flexure (8%), descending (20%), sigmoid (41%), rectum (23%) • Morphology ○ Sessile polyps: Broad base with little or no stalk ○ Pedunculated polyps: Arise from narrow stalk • General features ○ 2 types of colon polyps – Neoplastic: Adenomatous (tubular, tubulovillous, and villous) – Nonneoplastic: Hyperplastic, hamartomatous, and inflammatory

CT Findings • CT "virtual" colonography ○ Proven superior to barium enema and now considered primary radiographic alternative to optical colonoscopy – Technique primarily validated by national CT colonography trial conducted by ACRIN, which showed sensitivity of 90% and specificity of 86% – Polyps 10 mm: Sensitivity of 90% per patient, 84% per polyp – Detection of small polyps (< 1 cm) much less reliable ○ Technique considerations – Optimally performed after administration of colon cleansing agent (using either a "wet" or "dry" laxative preparation) and stool "tagging" agent □ Tagging agents cause fecal residue to appear radioopaque and easier to distinguish from polyps □ "Dry" cathartics (i.e., magnesium citrate or sodium phosphate) preferred as they induce less fluid in colon compared to "wet" cathartics (i.e., polyethylene glycol) □ Clear liquid diet (no solids) day prior to scan – Colon insufflated with CO₂ using electronic insufflator to 25 mm Hg – Separate supine and prone acquisitions allow differentiation of stool from polyps, better distension of some parts of colon, and redistribute fluid and fecal material (allowing better evaluation of entire mucosa) □ Images best acquired in end expiration to minimize mass effect by lungs upon transverse colon □ Additional left or right decubitus positioning may be necessary if portions of colon are not distended ○ Interpretation – Polyps appear as small or large, sessile or pedunculated, lesions extending from colon wall – Images reviewed in 2D (axial data set) or 3D (endoluminal 3D reconstructions)

– Computer aided detection (CAD) systems may serve as diagnostic adjunct to routine image review – As with barium enema, "flat" or "carpet" lesions can be challenging to detect on CT colonography – Polyps measuring 5 mm generally not reported due to low specificity and low risk of malignancy – Polyps measuring 1 cm referred for polypectomy – Management of 6-9 mm polyps debatable and can be managed with either CT surveillance or polypectomy ○ Reporting system (C-RADS) – Colorectal findings (C0-C4) □ C0: Inadequate study □ C1: Normal or benign lesion (no polyps 6 mm) □ C2: Intermediate polyp (polyps 6-9 mm) □ C3: Possible advanced adenoma (polyps 10 mm) □ C4: Possible malignant colorectal mass (lesion extends beyond lumen, extracolonic invasion) – Extracolonic findings (E0-E4) □ E0: Study compromised by artifact □ E1: Normal extracolonic findings □ E2: Clinically unimportant finding □ E3: Likely unimportant but incompletely characterized □ E4: Potentially important extracolonic finding

Colon

TERMINOLOGY

Radiographic Findings • Air- (double) contrast barium enema (BE) ○ Limited in terms of sensitivity, with miss rates as high as 17% (up to 10% miss rate for polyps > 1 cm) – Limited in areas of colonic redundancy or overlap, including rectosigmoid and hepatic/splenic flexures ○ Sessile polyps – Dependent wall: Radiolucent filling defect – Nondependent wall: Ring shadow with barium-coated white rim – Bowler hat sign: Brim and dome of hat represent base and head of polyp, with dome of hat pointing towards lumen of bowel (en face view) ○ Pedunculated polyps – Mexican hat sign: Pair of concentric rings with outer and inner rings representing head and stalk of polyp ○ Tubular adenomatous polyps – Small in size and often pedunculated with only minor degree of villous changes ○ Tubulovillous adenomatous polyps – Medium-sized, sessile polyps with fine nodular or reticular surface pattern and filling of barium within interstices of adenoma ○ Villous adenomatous polyps – Larger, sessile polyps with barium trapped between frond-like projections, resulting in granular or reticular pattern – lobulation, reticulation, or granulation in polyp usually associated with greater villous component ○ "Carpet" lesion – "Flat" lesions resulting in only subtle changes in colon surface texture with little or no protrusion into lumen □ Irregular contour in contrast to smooth, fine contour of adjacent normal bowel (profile view)

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Colon

Colonic Polyps □ Tiny, coalescent nodules and plaques create finely nodular or reticular pattern with sharply demarcated border (en face view) – Most often in rectum, cecum, and ascending colon ○ Hyperplastic polyps – Most commonly appear as smooth round sessile nodules measuring < 5 mm in rectosigmoid colon ○ Hamartomatous polyps – Multiple scattered polyps of variable size ○ Inflammatory polyps – Islands of elevated, inflamed, edematous mucosa surrounded by ulceration (inflammatory) – Small and round, long and filiform or bush-like; may simulate villous adenoma (postinflammatory)

– Inflammatory polyps (e.g., ulcerative colitis) □ Result from mucosal ulceration and nodular tissue regeneration due to several inflammatory bowel disease (usually ulcerative colitis) – Risk factors for development of acquired polyps: Diet, alcohol, smoking, and obesity ○ Pathogenesis – Spectrum of adenomatous polyps: Tubular tubulovillous villous – All adenomatous polyps contain foci of dysplasia and represent potential precursors to colon carcinoma – Transformation of adenomatous polyps follows adenoma-carcinoma sequence (may take 7-10 years) – Small minority of adenomas develop into malignancy (< 5%), but most cancers start as adenomas – Biggest risk factors for frank malignancy relate to lesion size, presence of multiple polyps, villous changes, and carpet lesions – Risk of colon carcinoma directly linked to polyp size □ Polyps: < 1 cm (1% with cancer), 1-2 cm (10-20%), > 2 cm (40-50%) □ Tubular adenoma: < 1 cm (1% with cancer), 1-2 cm (10%), > 2 cm (35%) □ Tubulovillous adenoma: < 1 cm (4% with cancer), 12 cm (7%), > 2 cm (46%) □ Villous adenoma: < 1 cm (10% with cancer), 1-2 cm (10%), > 2 cm (53%)

Imaging Recommendations • Best imaging tool ○ CT colonography (CTC)

DIFFERENTIAL DIAGNOSIS Retained Fecal Debris • Should be mobile and on dependent surface in barium pool • Irregularly shaped and often with internal contrast or gas • Proper bowel cleanse, tagging agents, and supine/prone views on CT colonography can help avoid confusion

Colon Carcinoma • Any polyp can contain foci of invasive carcinoma, and biopsy necessary to differentiate malignancy from benign polyp

Colonic Diverticulosis

Presentation

• Diverticula arising from nondependent wall may simulate polyp when viewed en face on barium enema: Ring shadow with barium-coated white rim ○ Rotate patient 90° to see outpouchings from wall vs. protrusion into lumen (profile view) ○ Bowler hat sign: Dome of hat points away from lumen

• Most common signs/symptoms ○ Usually asymptomatic (75%), but can rarely cause rectal bleeding, lower abdominal pain, and diarrhea

PATHOLOGY General Features • Etiology ○ Hereditary genetic syndromes – Adenomatous polyps (e.g., hereditary nonpolyposis colorectal cancer [Lynch syndrome], familial polyposis, Gardner and Turcot syndromes) – Hamartomatous polyps (e.g., Peutz-Jeghers and juvenile polyposis) ○ Acquired – Adenomatous polyps (e.g., sporadic adenoma) □ Villous adenomas most commonly occur in rectum – Hyperplastic polyps □ Most common nonneoplastic polyp of colon □ Extremely low risk of malignant transformation □ Classically located in rectosigmoid colon and typically very small (< 5 mm) – Hamartomatous polyps (e.g., Cronkhite-Canada syndrome) □ Disorganized growth of normal tissue elements □ Classically considered benign, but can very rarely develop dysplasia and lead to colon cancer 518

CLINICAL ISSUES

Demographics • Gender ○ Adenomatous polyps more common in men (M:F = 2:1) • Epidemiology ○ Prevalence with age: 3rd decade (3%), 4th (5%), 5th (7%), 6th (11%), 7th (10%), 8th (18%), 9th (26%) ○ age incidence of polyps shifts to right colon

Treatment • Any polyp 1 cm on barium enema or CT colonography should undergo colonoscopic polypectomy ○ Small polyps usually completely removed via biopsy or electrocautery, while larger lesions may require followup colonoscopies (or even surgery) to ensure that polyp is completely removed ○ Follow-up based on histology and number of lesions • In patients with neoplastic polyps caused by genetic mutations, prophylactic colectomy may be necessary

SELECTED REFERENCES 1.

Pooler BD et al: CT Colonography Reporting and Data System (C-RADS): benchmark values from a clinical screening program. AJR Am J Roentgenol. 202(6):1232-7, 2014

Colonic Polyps Colon

(Left) Air-contrast barium enema shows numerous diverticula and a large pedunculated polyp on a stalk in this patient with a tubulovillous adenoma. In a patient with known diverticulosis, it is often much easier to perform and interpret a single-contrast rather than an air- (double) contrast barium enema. (Right) Air-contrast barium enema shows a small sessile tubular adenoma . The dome of the "bowler hat" points toward the colonic lumen.

(Left) Axial CT colonography demonstrates a small, sessile adenomatous polyp arising from the cecum. (Right) 3D endoluminal view in the same patient nicely shows the morphology of the polyp . The decision to interpret CT colonography using 2D or 3D reconstructions largely hinges on the comfort level of the interpreting radiologist.

(Left) Axial CT colonography shows a pedunculated polyp on a long stalk . (Right) Endoluminal 3D reconstruction in the same patient nicely demonstrates the polyp and its associated stalk. When measuring such a lesion, the reported size should optimally be based on the diameter of the "head" rather than the length of the stalk.

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Colon

Villous Adenoma KEY FACTS

TERMINOLOGY • Adenomatous polyp that contains predominantly villous ("shaggy" surface) elements ○ Accounts for 5-15% of colonic adenomas

IMAGING • Polypoid lesion with nodular or frond-like surface on BE or CT colonography • Location: Rectosigmoid > cecum > ascending colon > stomach > duodenum • Villous adenoma is 1 histological type of adenomatous polyps (true neoplasms) • Risk of cancer is related to tumor size, location, and proportion of villous change in adenoma • Greater risk of carcinoma in villous tumors of stomach and duodenum than colon ○ Stomach: Carcinoma in 50% of lesions 2-4 cm and in 80% of lesions > 4 cm in size ○ Colon: Invasive carcinoma in up to 45% of cases

(Left) Graphic shows a polypoid mass in the rectosigmoid colon having a shaggy, nodular surface, sometimes likened to the surface of a cauliflower. (Right) Single contrast barium enema shows a large rectal mass with a frond-like surface. Note the absence of a colonic obstruction, a typical feature of this soft and compressible tumor.

(Left) This 70-year-old man complained of frequent passage of watery stool, but had no symptoms of bowel obstruction. CT shows a large mass that fills the rectum. Note large vessels within and draining the mass. (Right) Coronal CT reformation in the same case shows the huge size of the mass , but no definite signs of invasion through the rectal wall and no metastases. The resected villous adenoma had foci of frank carcinoma.

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• CT: Large villous adenoma ○ Low-attenuation, minimally enhancing, irregular polypoid mass ○ Corrugated, feathery appearance due to trapping of enteric contrast • Transrectal US; plus CT or MR for staging

TOP DIFFERENTIAL DIAGNOSES • Colon carcinoma • Fecal mass

PATHOLOGY • Malignant potential: Lesions < 1 cm (5%), 1-2 cm (10%), > 2 cm (53%)

CLINICAL ISSUES • Asymptomatic, diarrhea, pain, rectal bleeding, or melena • Lesion closer to rectum: More likely to have diarrhea, electrolyte loss (hypokalemia and hyponatremia)

Villous Adenoma

Synonyms • Villous tumor

Definitions • Adenomatous polyp that contains predominantly villous ("shaggy" surface) elements

IMAGING General Features • Best diagnostic clue ○ Polypoid lesion with nodular or frond-like surface on barium enema or CT colonography • Location ○ Rectosigmoid > cecum > ascending colon > stomach > duodenum • Size ○ Range from < 1 to > 10 cm in diameter • Morphology ○ Cauliflower-like sessile growth with broad base or flat "carpet" lesion • Other general features ○ Villous adenoma is 1 histological type of adenomatous polyps (true neoplasms) – Tubular adenoma: > 80% of neoplastic polyps – Villous adenoma: 5-15% of colonic polyps, villous morphology in > 75% of lesion – Tubulovillous adenoma: 5-15% of all colonic polyps ○ As adenoma increases in size, degree of villous change usually increases ○ Risk of cancer is related to size, location, and proportion of villous change in adenoma ○ Greater risk of carcinoma in villous tumors of stomach and duodenum than colon – Stomach: Carcinoma in 50% of lesions 2-4 cm and in 80% of lesions > 4 cm – Duodenum: Carcinoma in 30-60% of villous tumors > 4 cm – Colon: Carcinoma in situ in 10% and invasive carcinoma in up to 45% of cases

Radiographic Findings • Fluoroscopic-guided double contrast barium enema ○ 2 types of villous adenomas – Polypoid mass – "Carpet" lesion ○ Polypoid mass – May look cauliflower-like within colon – Nodular, "lace," or "soap bubble" pattern – Due to trapping of barium between frond-like projections (interstices) – Malignant transformation in bulky adenoma: Annular lesion with shelf-like, overhanging borders ○ "Carpet" lesion – Flat, lobulated lesion – Localized or extensive ○ Localized "carpet" lesion: Subtle alteration in surface texture

○ Extensive "carpet" lesion: Involves large area of colon, encircling lumen – En face: Fine nodular, reticular pattern with sharply demarcated border – Profile: Irregular contour in contrast to smooth, fine contour of adjacent normal bowel

Colon

TERMINOLOGY

CT Findings • Large villous adenoma ○ Low-attenuation, minimally enhancing, irregular polypoid mass ○ Convolutional gyral enhancement pattern ○ Corrugated, feathery appearance due to trapping of enteric contrast within interstices of villous adenoma • CT colonography ○ Appearance of villous tumors similar to that seen on barium enema ○ CTC shows more polyps than barium enema

MR Findings • Large villous adenoma ○ T1WI: Low signal intensity mass with multiple frond-like projections and central cord-like structure ○ T2WI: Frond-like projections will be more prominent • Villous adenoma with more mucin-producing cells ○ Short T1 and long T2 times ○ Adenoma appears hyperintense on both T1- and T2WI

Ultrasonographic Findings • Transrectal sonography ○ Determines depth of invasion into colonic wall by adenoma

Imaging Recommendations • CT colonography (or barium enema) for screening • Transrectal US; plus CT or MR for staging

DIFFERENTIAL DIAGNOSIS Colon Carcinoma • Barium enema findings ○ Early cancer: Sessile (plaque-like) lesion – Typical early colon cancer – Flat, protruding lesion with broad base and little elevation of mucosa (in profile view) ○ Early cancer: Pedunculated lesion – Short and thick polyp stalk – Irregular or lobulated head of polyp ○ Advanced cancer: Polypoid lesion (large) – Dependent wall: Filling defect in barium pool – Nondependent wall: Surface of tumor is etched in white ○ Sessile and pedunculated polypoid cancers may be indistinguishable from villous adenoma ○ Advanced cancer: Semiannular ("saddle") lesion ○ Advanced cancer: Annular ("apple core") lesion – Circumferential narrowing of bowel – Shelf-like, overhanging borders (mucosal destruction) • CT findings ○ Asymmetric mural thickening ± irregular surface ○ Extracolonic tumor extension – Mass with irregular borders 521

Colon

Villous Adenoma

– Extension from serosa to pericolic fat – Loss of fat planes: Colon and adjacent muscles ○ Metastases to regional mesenteric nodes ○ Metastases to liver • Diagnosis: Biopsy and histology

Fecal Mass • Large, irregular colonic fecal impaction ○ Most common location: Rectum • Mimics large, cauliflower-like sessile polyp • May cause bowel obstruction and proximal dilatation • Usually seen in elderly, sedentary patients • Diagnosis: Clinical history and colonoscopy

Intramural Benign Tumor, Colonic • e.g., stromal tumors (leiomyoma, sarcoma, or GIST) • Leiomyoma ○ In profile – Smooth surface, etched in white – Borders: Right or obtuse angles with adjacent wall ○ En face – Seen as filling defect simulating polypoid type of villous adenoma – Intraluminal surface: Abrupt, well-defined borders • Leiomyosarcoma ○ Bulky stromal tumors most frequently seen in rectum ○ Broad-based mass simulating large villous adenoma ○ Large tumors show ulceration or cavitation ○ CT shows pericolonic extension (large extraluminal mass), liver, and peritoneal metastases • Hypervascular on angiography • Diagnosis: Biopsy

PATHOLOGY General Features • Etiology ○ Villous adenoma or tumor – Family history, idiopathic inflammatory disease – Malignant potential: Lesions < 1 cm (5%), 1-2 cm (10%), > 2 cm (53%)

Gross Pathologic & Surgical Features • Usually sessile ○ May be polypoid, broad, flat, or carpet-like lesion ○ Gray-tan lesion • May have short, broad stalk and focal areas of hemorrhage or ulceration

Microscopic Features • Frond-like papillary projections of adenomatous epithelium • ± well-differentiated areas • Carcinoma in situ, invasive cancer

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic, diarrhea, pain, rectal bleeding, or melena ○ Lesion closer to rectum: More likely to have diarrhea, electrolyte loss (hypokalemia) • Lab data 522

○ Guaiac positive stool ○ Iron deficiency anemia ○ Decreased serum protein, K+, Na+ – "McKittrick-Wheelock syndrome" if caused by rectal tumor, usually villous adenoma ○ ± increased direct bilirubin levels (due to obstruction of ampulla of Vater by adenoma) • Diagnosis: Endoscopy, biopsy, and histology

Demographics • Age ○ 60-70 years or older • Gender ○ M=F

Natural History & Prognosis • Complications ○ Malignant transformation or invasion; hemorrhage • Prognosis ○ Good: After removal of benign and carcinoma in situ adenoma ○ Poor: Invasive carcinoma

Treatment • Colonoscopic, endoscopic, or surgical resection

DIAGNOSTIC CHECKLIST Consider • Check for family history of colonic polyps and evaluate entire colon for synchronous lesions

Image Interpretation Pearls • Cauliflower-like sessile mass with broad base or "carpet" lesion with reticular or "soap bubble" surface pattern • Luminal obstruction is a late finding

SELECTED REFERENCES 1.

2.

3.

4.

5. 6.

7.

8. 9.

Serra-Aracil X et al: Transanal endoscopic surgery with total wall excision is required with rectal adenomas due to the high frequency of adenocarcinoma. Dis Colon Rectum. 57(7):823-9, 2014 Bozkurt N et al: Adenoma with rectal villous diarrhoea and severe hypokalaemia (McKittrick-Wheelock syndrome). Br J Hosp Med (Lond). 74(11):648-9, 2013 Sanchez Garcia S et al: Hypersecretory villous adenoma as the primary cause of an intestinal intussusception and McKittrick-Wheelock syndrome. Can J Gastroenterol. 27(11):621-2, 2013 Sosna J et al: Critical analysis of the performance of double-contrast barium enema for detecting colorectal polyps > or = 6 mm in the era of CT colonography. AJR Am J Roentgenol. 190(2):374-85, 2008 Ferrucci JT: Double-contrast barium enema: use in practice and implications for CT colonography. AJR Am J Roentgenol. 187(1):170-3, 2006 Taylor SA et al: Comparison of radiologists' confidence in excluding significant colorectal neoplasia with multidetector-row CT colonography compared with double contrast barium enema. Br J Radiol. 79(939):208-15, 2006 Johnson CD et al: Comparison of the relative sensitivity of CT colonography and double-contrast barium enema for screen detection of colorectal polyps. Clin Gastroenterol Hepatol. 2(4):314-21, 2004 Smith TR et al: CT appearance of some colonic villous tumors. AJR Am J Roentgenol. 177(1):91-3, 2001 Chung JJ et al: Large villous adenoma in rectum mimicking cerebral hemispheres. AJR Am J Roentgenol. 175(5):1465-6, 2000

Villous Adenoma Colon

(Left) Barium pool image from a double contrast barium enema shows a cauliflowerlike mass in the cecum, a typical appearance of a villous adenoma. (Right) Spot film from an air contrast barium enema in the same patient shows the villous adenoma coated with barium and outlined by air on this view.

(Left) Axial CECT in an 85year-old woman with acute abdominal pain shows a transverse colo-colonic intussusception due to a large lead point mass . (Right) More caudal CT section in the same patient shows the colonic mass , a villous adenoma, as the lead point of the colonic intussusception.

(Left) Axial CECT in the same patient just proximal to the intussusception shows another smaller, lobulated, enhancing mass within the ascending colon that proved to be a 2nd villous adenoma. (Right) Single contrast BE in the same patient demonstrates temporary reduction of the intussusception, with the 2 villous adenomas seen as masses with irregular surface contours within the barium pool. A right hemicolectomy and histopathology confirmed the diagnosis.

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Colon

Colon Carcinoma KEY FACTS

IMAGING • Radiology is critical for detection, diagnosis, staging, and follow-up of colorectal carcinoma (CRC) • Detection: Air-contrast barium enema or CT colonography ○ Early cancer: Sessile or pedunculated polyp ○ Advanced cancer: "Saddle" or "apple core" lesion – Circumferential narrowing of bowel lumen, overhanging borders, mucosal destruction • Staging: Helical CT ± MR ○ Asymmetric mural thickening ± irregular surface ○ Pericolonic fat infiltration; spread to adjacent organs ○ Metastases to mesenteric nodes, peritoneum, liver – MR is more sensitive than CT for evaluation of liver metastases (especially with Eovist enhancement) ○ Tumor recurrence and surveillance: PET/CT – FDG-avid lesions in chest, abdomen, pelvis

TOP DIFFERENTIAL DIAGNOSES • Diverticulitis

(Left) Graphic shows an "apple core" constricting tumor of the sigmoid colon with circumferential narrowing of the lumen and a nodular tumor surface, the typical appearance of a left-sided cancer. These patients often complain of constipation and rectal bleeding. (Right) Singlecontrast barium enema shows a classic "apple core" lesion of the sigmoid colon. Note the short segment, irregular, circumferential narrowing of the lumen with destroyed mucosa and nodular "shoulders."

(Left) Coronal image in 2D from a CT colonography shows a mass in the sigmoid due to colon cancer. While this mass was sufficiently large to prevent passage of the colonoscope, it was possible to both cleanse and distend the colon proximal to the mass using routine CT colonography methods. (Right) CT 3D endoluminal view in the same patient shows the mass and its relationship to the remainder of the colon. One of the accepted indications for CT colonography is to screen the colon proximal to an obstructing lesion.

524

• • • •

Ischemic colitis Infectious colitis with TB or ameba Ulcerative colitis Endometriosis

PATHOLOGY • Importance of family history ○ CRC in 1st-degree relatives ( risk 2-3x) ○ Familial adenomatous polyposis – Accounts for < 1% of all colon cancers) ○ Hereditary nonpolyposis colorectal carcinoma – Accounts for 5% of all colon cancers

CLINICAL ISSUES • New treatments for metastatic disease (e.g., resection and ablation) offer hope for cure or prolonged survival ○ Demands accurate staging and surveillance for recurrence

Colon Carcinoma

Abbreviations • Colorectal carcinoma (CRC)

Definitions • Malignant transformation of colonic mucosa

IMAGING General Features • Best diagnostic clue ○ Short segment luminal wall thickening • Location ○ Cecum (10%), ascending colon (15%), transverse colon (15%), descending colon (5%), sigmoid colon (25%), rectosigmoid colon (10%), rectum (20%) • Morphology ○ Early cancer: Sessile or pedunculated polyps ○ Advanced cancer: Annular, semiannular, polypoid, or carpet tumors • Other general features ○ Radiology is critical for screening, diagnosis, treatment, and follow-up of CRC ○ Screening: Fluoroscopic-guided double-contrast barium enema and CT "virtual colonoscopy" are comparable to colonoscopy for cancer detection by experienced observers

Radiographic Findings • On air-contrast barium enema or CT colonography ○ Early cancer: Plaque-like lesion – Flat, protruding lesion with little elevation of surface ○ Early cancer: Pedunculated lesion – Short and thick polyp stalk – Irregular or lobulated head of polyp ○ Advanced cancer: Polypoid lesion (large) – Dependent wall: Filling defect in pool of contrast – Nondependent wall: Etched in white ○ Advanced cancer: Semiannular "saddle" lesion – Transition to annular carcinoma: Polypoid semiannular annular – Convex barium-etched margins (in profile view) ○ Advanced cancer: Annular "apple core" lesion – Circumferential narrowing of bowel lumen, overhanging borders, mucosal destruction – High-grade obstruction with ischemia: Thumbprinting of dilated proximal colon

CT Findings • Asymmetric mural thickening of soft tissue density ± irregular surface • Tumor limited to lumen: Smooth serosal surface • Extracolonic tumor extension ○ Mass with irregular serosal surface with stranding of pericolonic fat ○ Loss of tissue fat planes between colon and surrounding muscles • Metastases to mesenteric nodes, peritoneum • Hepatic metastases are most common (via portal venous drainage)

MR Findings • MR is more sensitive than CT for evaluation of liver metastases • Performed with gadoxetate (Eovist, Primavist) enhancement ○ Even better sensitivity (not specificity) ○ Metastases are hypointense to avidly enhanced normal liver parenchyma

Colon

TERMINOLOGY

Nuclear Medicine Findings • PET ○ Fluorine 18-labeled deoxyglucose uptake is 2x higher in tumors than in normal/nonmalignant lesions • PET CT ○ Best combination of morphology and pathophysiology

Imaging Recommendations • Best imaging tool ○ Detection: Air-contrast barium enema or CT colonography ○ Staging: CECT ○ Tumor recurrence and surveillance: PET/CT

DIFFERENTIAL DIAGNOSIS Diverticulitis • CT: Most common in sigmoid colon ○ Bowel wall and fascial thickening; fat stranding; free air and fluid ○ Pericolic inflammatory changes: Abscess, sinuses, fistulas, or strictures ○ Length of involvement > 10 cm – Cancer: Short segment involvement ± nodal enlargement

Ischemic Colitis • Usually seen in watershed areas; splenic flexure and sigmoid colon ○ Thumbprinting: Submucosal gas, edema, or bleeding ○ Stricture: Smooth, tapered margins, but no mass effect (chronic)

Infectious Colitis (Unusual Organisms) • Example: Tuberculosis and amebiasis • Usually in proximal colon • Stricture formation may simulate carcinoma

Ulcerative Colitis • Significant etiology of colon carcinoma ○ Cancers arise de novo in inflamed mucosa without going through polyp stage • Bowel wall thickening, luminal narrowing, mesenteric hyperemia

Extrinsic Lesions • Endometriosis • Ovarian cancer • Direct spread or "drop" metastases (e.g., from gastric cancer) • Smooth, eccentric, obtuse angles with colonic wall

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Colon

Colon Carcinoma

PATHOLOGY General Features

Presentation

• Etiology ○ Risk factors – fiber, fat, animal protein in diet – History of colon adenoma or carcinoma – Benign polyps > 1 cm – Inflammatory bowel disease ○ Family history – CRC in 1st-degree relatives ( risk 2-3x) – Familial adenomatous polyposis (accounts for < 1% of all colon cancers) – Hereditary nonpolyposis CRC (accounts for 5% of all colon cancers) □ Type 1: CRC alone □ Type 2: Plus endometrial, ovary ± breast carcinoma □ Autosomal dominant □ Tumors arise in discrete adenomas, not diffuse polyposis ○ Pathogenesis – Adenoma-carcinoma sequence (7-10 years) □ Benign adenoma malignant transformation – Inflammatory bowel disease: Inflammation dysplasia carcinoma • Genetics ○ Mutations of genes – Proto-oncogene (KRAS): 50% of CRC – Deletion of tumor suppressor genes (APC, DCC, SMAD4, p53, TGF-β1 RII) □ Found in up to 75% of patients with CRC – DNA mismatch repair genes: 15% of colon cancers • Associated abnormalities ○ Metachronous carcinomas; 5% of CRC ○ Additional adenomatous polyps: 33% of CRC ○ Colitis (called necrotizing, ulcerative or ischemic) may result from more distal obstructing colon carcinoma

• Most common signs/symptoms ○ Distal colon: Colonic obstruction and hematochezia – Abdominal pain and changes in bowel habits ○ Proximal colon: Anemia, weight loss, fever • Lab data ○ Positive fecal occult blood test ○ ± micro- to normocytic anemia ○ Carcinoembryonic antigen (CEA) > 2.5 μg/L • Diagnosis: Colonoscopy with mucosal biopsy

Staging, Grading, & Classification

• Complete surgical resection ( 5 cm on each side of tumor) with removal of lymphatic drainage vessels ± adjuvant chemotherapy • Pre- and postoperative radiation therapy (selected cases) • Follow-up ○ CT: Follow-up 3-4 months after surgery, then every 6 months for 2-3 years, then annually for 5 years ○ CEA titer: If elevated, CT is indicated ○ PET/CT: Best for recurrence and surveillance

• Surgical-pathologic (modified Dukes) staging of colon cancer with TNM correlation ○ Stage A (T1N0M0): Limited to mucosa ± submucosa ○ Stage B (T2 or 3 and N0M0): Limited to serosa or into adjacent tissues ○ Stage C (T2 or 3 and N1M0): Lymph node metastases ○ Stage D (any T and N, M1): Distant metastases

Gross Pathologic & Surgical Features • Cecum and proximal colon: Bulky and polypoid, outgrowing blood supply necrosis • Distal colon and rectum: Annular constriction or napkin-ring appearance obstruction ulceration

Microscopic Features • Adenocarcinoma (> 95% of colon cancers) ○ Mucin-producing glands ○ Mucinous: Signet ring cells ○ Colloid (15%): Large lakes of mucin contain scattered collections of tumor cells • Squamous cell carcinoma (< 5%) 526

CLINICAL ISSUES

Demographics • Age ○ > 50 years; peak at 70 years • Gender ○ M:F = 3:2 • Epidemiology ○ Most common cancer of gastrointestinal tract in Western society ○ 2nd most common cancer mortality (men and women) ○ More common in North America, Europe, and New Zealand – Incidence in USA: 150,000 per year – Mortality in USA: > 50,000 per year ○ With age incidence of cancer shifts to right colon

Natural History & Prognosis • Prognosis ○ Overall 5-year survival is 50% (improving with treatment of metastatic disease) – Dukes stage A: 81-85% – Dukes stage B: 64-78% – Dukes stage C: 27-33% – Dukes stage D: 5-14%

Treatment

DIAGNOSTIC CHECKLIST Consider • Evaluate entire colon for synchronous lesions

Image Interpretation Pearls • CT: Short segment circumferential wall thickening with cluster of mesenteric nodes is presumed CRC

SELECTED REFERENCES 1.

Brenner H et al: Colorectal cancer. Lancet. 383(9927):1490-502, 2014

Colon Carcinoma Colon

(Left) Axial CECT in a 60-yearold man with right-sided CRC presenting with anemia and liver metastases shows a metastasis and an incidental cyst . (Right) Axial CECT of the same patient shows a mass in the ascending colon . Note the ileocolic mesenteric adenopathy . The presence of mesenteric adenopathy adjacent to a colonic mass is strong evidence for lymphatic spread of a primary colon cancer.

(Left) Axial CECT in a middleaged man with RLQ discomfort shows multiple nodular omental metastases . (Right) CT in the same patient shows a circumferential soft tissue mass in the cecum that obstructed the appendix and invaded adjacent mesenteric fat and nodes. Cecal carcinoma may mimic appendicitis with cecal wall thickening, infiltrated fat, and distended appendiceal lumen. The presence of a circumferential cecal mass and omental (or liver) metastases indicates a malignant process.

(Left) Axial CECT of a 61-yearold woman with constipation with acute onset of abdominal pain and fever shows dilation of the colon with fluid and gas, plus infiltration of the pericolonic fat . (Right) More caudal CT section in the same case shows a large mass arising from the sigmoid colon causing the colonic obstruction. Also note the ascites and infiltrated fat planes adjacent to the colon. Surgery confirmed carcinoma of the sigmoid colon with ischemic colitis of the descending colon.

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Colon

Colon Carcinoma

(Left) Upright chest radiograph of an 82-year-old woman who complained of distention and sudden abdominal pain shows free intraperitoneal gas and a distended colon . (Right) Coronal-reformatted CT section in the same case shows stool and gas distending the colon . Ascites and free air were also evident. A distal colon cancer is one of the most common causes for colonic obstruction in older adults.

(Left) Axial CT section in the same case shows an "apple core" obstructing lesion of the sigmoid colon. Note the short segment, soft tissue density of the wall thickening and luminal narrowing. (Right) More caudal CT section in the same case shows extraluminal gas and ascites , indicating perforation of the colon.

(Left) CT of a 66-year-old man who had prior resection of a sigmoid colon cancer and now presents with flank pain and weight loss shows a descending colostomy and extensive retroperitoneal lymphadenopathy that enveloped the left ureter and caused hydronephrosis (not shown). (Right) Axial PET/CT in the same case shows large FDG-avid masses that envelop and obstruct the left ureter, representing recurrent colon carcinoma. In cases of suspected recurrence of CRC, PET/CT is the optimal test.

528

Colon Carcinoma Colon

(Left) Axial CT section of a 31year-old man presenting with constipation and bright red blood per rectum shows gross dilation of the colon . (Right) CECT in the same case shows asymmetric, soft tissue density thickening of the wall of the descending colon .

(Left) Adjacent CECT section in the same case shows an "apple core" lesion at the junction of the descending and sigmoid colon. (Right) Coronalreformatted CT in the same case shows gross distention of the colon with stool and gas.

(Left) Another coronal CT section shows the abrupt narrowing of the colon by the "apple core" lesion . Note the abrupt and short thickening of the colonic wall and narrowing of the lumen. The clinical and imaging features are typical of a distal colon cancer, though the patient is younger than most affected patients. (Right) In order to overcome the nearcomplete luminal obstruction and to clean the colon prior to surgical resection, a metallic stent was deployed across the obstructing tumor under endoscopic guidance .

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Colon

Rectal Carcinoma KEY FACTS

IMAGING

• PET/CT: Excellent for staging and recurrence

• CT, MR: Asymmetric mural thickening ± irregular surface ○ Extracolonic tumor extension: Irregular external (serosal) margin of rectum ○ Strands of soft tissue extending from serosal surface into perirectal fat ○ Loss of tissue fat planes between rectum and surrounding muscles and organs ○ Metastasis to lymph nodes at external iliac and paraaortic chain, inguinal, retroperitoneum, or porta hepatis • Mass; pericolonic infiltration, lymphadenopathy may be shown better on MR than CT • Transrectal ultrasonography: Best for local invasion, pelvic nodes • May have lung and bone metastases before liver metastases (unlike typical pattern for colon carcinoma) ○ Due to dual venous drainage, including internal iliac and hemorrhoidal veins

TOP DIFFERENTIAL DIAGNOSES

(Left) Axial CECT in a 68-yearold man with frequent passage of small amounts of mucus and stool shows a large rectal mass that breaks through the rectal wall , interrupting the otherwise complete rectal mucosal enhancement. There was no colonic obstruction, suggesting the soft nature of this villous carcinoma. (Right) CT in the same patient shows extensive infiltration of the perirectal fat planes , strongly suggesting transmural spread of tumor and the need for neoadjuvant therapy prior to resection.

(Left) Transrectal ultrasonography shows a bulky rectal mass with invasion through the submucosa in this patient with T3 stage rectal carcinoma. (Right) Axial CECT shows extensive pulmonary metastases from rectal carcinoma in a patient with no liver metastases. The dual venous drainage of the rectum (systemic and portal) explains this pattern and results in very different clinical behavior of rectal and colon cancers.

530

• Invasion by adjacent tumor (cervix, prostate, bladder) • Rectal villous adenoma • Trauma or infection

PATHOLOGY • Adenocarcinoma: Arises from mucin-producing glands (80% of rectal tumors) • Squamous cell (cloacogenic) carcinoma (20% of rectal tumors)

DIAGNOSTIC CHECKLIST • Image detection of perirectal tumor spread is vital; requires preoperative radiation ± chemotherapy

Rectal Carcinoma

Definitions • Malignant transformation of rectal mucosa

IMAGING General Features • Best diagnostic clue ○ Polypoid rectal mass with irregular surface • Morphology ○ Early cancer: Sessile or pedunculated tumors ○ Advanced cancer: Annular, semiannular, polypoid or "carpet" tumors ○ Most common in rectum: Sessile and polypoid • Other general features ○ Radiologic and histologic features are similar to colon carcinoma

Radiographic Findings • Fluoroscopic-guided barium enema ○ Early cancer: Sessile (plaque-like) lesion – Flat, protruding lesion with broad base and little elevation of mucosa (profile view) ○ Advanced cancer: Polypoid lesion – Dependent wall: Filling defect in barium pool – Nondependent wall: Etched in white ○ Advanced cancer: Semiannular ("saddle") lesion – Transition to annular carcinoma ("apple core") – Convex barium-etched margins (profile view)

CT Findings • Mass and focal or circumferential wall thickening • Asymmetric mural thickening (> 6 mm) ± irregular surface • Extracolonic tumor extension ○ Mass with irregular external (serosal) border ○ Strands of soft tissue extending from serosal surface into perirectal fat ○ Loss of tissue fat planes between rectum and surrounding muscles and organs • Metastasis to lymph nodes at external iliac and paraaortic chain, inguinal, retroperitoneum, or porta hepatis • May have lung and bone metastases before liver metastases ○ Due to dual venous drainage, including internal iliacs

MR Findings • Mass; pericolonic infiltration, lymphadenopathy slightly better than on CT ○ Same tumor morphology as on CT ○ Tumor is dark on T1WI, bright on T2WI and DWI • Endorectal coil: Improves resolution but may not be worth effort

Ultrasonographic Findings • Transrectal ultrasonography ○ Best means of determining depth of wall invasion and pelvic lymphadenopathy ○ Focal or circumferential wall thickening ○ Hypoechoic mass with disruption of wall layers ○ Metastases to lymph nodes: Spherical, hypoechoic, and distinct margins

Colon

○ Rings of different echogenicities (center outer) – Innermost ring: Hyperechoic; interface between balloon and mucosa – 2nd ring: Hypoechoic; muscularis mucosae – 3rd ring: Hyperechoic; submucosa – 4th ring: Hypoechoic; muscularis propria – 5th ring: Hyperechoic; perirectal fat or serosa ○ Sonographic staging based on TNM classification – T1: Confined to mucosa/submucosa; middle echogenic layer intact – T2: Confined to rectal wall; outermost echogenic layer is intact – T3: Penetrates into perirectal fat; disrupting outer hyperechoic ring

TERMINOLOGY

Nuclear Medicine Findings • PET/CT ○ Combines morphologic information (of CT) with metabolic information (of PET) ○ Excellent for staging and detection of recurrence ○ Fluorine 18-labeled deoxyglucose uptake is 2x higher in tumors than normal or nonmalignant lesions

Imaging Recommendations • Best imaging tool ○ Detection: Barium enema or CT colonography ○ Staging: CECT or MR plus transrectal ultrasonography (wall invasion and nodes) ○ Tumor recurrence, surveillance: PET/CT

DIFFERENTIAL DIAGNOSIS Invasion by Adjacent Tumor • • • •

Carcinoma of cervix Prostate carcinoma Bladder carcinoma Can be hard to differentiate from primary rectal tumor

Rectal Villous Adenoma • Polypoid lesion with granular, reticular, or "cauliflower" appearance • High risk of malignant degeneration • Similar to "carpet" lesion in advanced rectal cancer

Trauma • Penetrating injuries: Anal intercourse and insertion of foreign bodies • Fibrosis and stricture (chronic) can simulate cancer

Infection • Mucosal ulceration or granular mucosal pattern • Mechanism: Anal sex, spread from vaginal discharge, or lymphatic extension from inguinal lymph nodes • Most common: Chlamydia trachomatis lymphatic tissue infection lymphogranuloma venereum (LGV) • Other STDs include Neisseria gonorrhoeae, HSV, and syphilis • May progress to fistula, perirectal abscess, or stricture (chronic)

PATHOLOGY General Features • Etiology 531

Colon

Rectal Carcinoma

•

• • •

•

○ Adenocarcinoma – fiber + fat and animal protein diet – History of colorectal adenoma or carcinoma – Family history and inflammatory bowel disease ○ Squamous cell carcinoma – HIV-positive homosexual males – Human papillomavirus (HPV) types 16, 18, 45, 46 – Lubricants, cleansers, and mechanical irritation ○ Pathogenesis – Adenocarcinoma: Adenoma-carcinoma sequence – Squamous cell carcinoma: Squamous metaplasia dysplasia carcinoma Genetics ○ Adenocarcinoma: Mutation in proto-oncogene, tumor suppressor genes, or DNA mismatch repair genes Colon cancers: Rectum accounts for 20% and rectosigmoid 15% Rectal cancer tends to invade locally (lacks serosa) Metastases: From upper 2/3 of rectum ○ Portal system liver ○ Batson vertebral venous plexus lumbar and thoracic vertebra, periaortic nodes Metastases: From lower 1/3 of rectum ○ Superior hemorrhoidal vein portal liver ○ Middle hemorrhoidal vein IVC lung

Staging, Grading, & Classification • Surgical-pathologic (modified Dukes) staging of colon cancer with TNM correlation ○ Stage A (T1N0M0): Limited to mucosa ± submucosa ○ Stage B (T2 or 3 and N0M0): Limited to or invades adjacent tissues ○ Stage C (T2 or 3 and N1M0): Lymph node metastases ○ Stage D (any T and N, M1): Distant metastases

○ Sigmoidoscopy with mucosal biopsy

Demographics • Age ○ Adenocarcinoma: Age > 50 years, peak at 70 years • Gender ○ M:F = 3:2 • Epidemiology ○ Adenocarcinoma: More common in North America, Europe, and New Zealand

Natural History & Prognosis • Complications ○ Hemorrhage, obstruction, perforation, and fistula • Prognosis ○ Overall 5-year survival (50%) – Dukes stage A (81-85%) – Dukes stage B (64-78%) – Dukes stage C (27-33%) – Dukes stage D (5-14%)

Treatment • Surgical resection (depends on location) and removal of lymphatic drainage vessels ± adjuvant chemotherapy • Pre- and postoperative radiation ± chemotherapy therapy (for locally advanced tumor) • Follow-up ○ CT: 3-4 months after surgery, then every 6 months for 23 years, then annually for 5 years ○ CEA titer: If elevated, CT is indicated (PET/CT best)

DIAGNOSTIC CHECKLIST Consider • Evaluate entire colon for synchronous lesions

Gross Pathologic & Surgical Features

Image Interpretation Pearls

• Flat, infiltrative, annular or ulcerative, and rolled borders • Annular constriction or "napkin-ring" appearance obstruction, ulceration, and intramural spread • Squamous cell carcinoma: Mass from epithelium of anorectal junction (dentate line)

• Image detection of perirectal tumor spread is vital; requires preoperative radiation ± chemotherapy

SELECTED REFERENCES 1.

Microscopic Features • Adenocarcinoma: Arises from mucin-producing glands (80% of rectal tumors) • Squamous cell (cloacogenic) carcinoma (20% of rectal tumors) ○ Mixture of basaloid cell, transitional cell with squamous differentiation, adenoid cyst, and mucoepithelial cell

2. 3.

4.

5.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Hematochezia, rectal pain, change in bowel habits ○ Perineal or sacral pain (chronic) ○ Squamous cell carcinoma – Anal pain, anal discharge, and tenesmus • Lab data ○ HIV (PCR) test may be positive ○ Carcinoembryonic antigen (CEA) > 2.5 μg/L • Diagnosis 532

6. 7.

Lim SB et al: Nonoperative strategies for rectal cancer following a complete clinical response to preoperative chemoradiation: a few considerations. Oncology (Williston Park). 28(7):620-1, 2014 Minsky BD et al: MRI-based treatment decision making for rectal cancer. Oncology (Williston Park). 28(8):680-1, 2014 Monson JR et al: Failure of evidence-based cancer care in the United States: the association between rectal cancer treatment, cancer center volume, and geography. Ann Surg. 260(4):625-31; discussion 631-2, 2014 Winter D: Outcomes in locally advanced rectal cancer with highly selective preoperative chemoradiotherapy--editor's comments. Br J Surg. 101(10):1298, 2014 Hoffman JR et al: Carcinoma of the prostate with aggressive rectal invasion. Am Surg. 75(5):434-6, 2009 Platell C: Transanal endoscopic microsurgery. ANZ J Surg. 79(4):275-80, 2009 Shen SS et al: Number of lymph nodes examined and associated clinicopathologic factors in colorectal carcinoma. Arch Pathol Lab Med. 133(5):781-6, 2009

Rectal Carcinoma Colon

(Left) Axial PET/CT in a 54year-old man with AIDS shows an FDG-avid mass in the anal canal, representing a primary anorectal carcinoma. (Right) Axial PET/CT in the same patient shows similar FDG-avid masses in lymph node metastases in the porta hepatis. This patient had no liver metastases, again emphasizing the unique patterns of spread in rectal vs. colon cancer. Anal cancer is relatively common in homosexual men with AIDS and is related to papilloma viral infection.

(Left) Axial T1WI MR in a 58year-old woman with prior low anterior resection of a rectal carcinoma, now returning with right leg sciatica, shows a large irregular mass that extends into the right sciatic notch and posterior wall of the bladder . (Right) Axial T2WI MR in the same patient shows the recurrent rectal cancer and its invasion of the bladder and pelvic side wall muscles .

(Left) Axial CECT in a young woman who underwent colectomy for granulomatous colitis shows a circumferential mass within the rectum that represents carcinoma. Note the adenopathy adjacent to the rectum and the tumor in the sciatic foramen . (Right) Axial PET/CT in the same patient shows an FDG-avid tumor in the rectum and in the sciatic foramen . The bladder is filled with urine containing excreted FDG.

533

Colon

Familial Polyposis and Gardner Syndrome KEY FACTS

• Autosomal dominant genetic disorder characterized by formation of innumerable colonic adenomatous polyps at young age and increased risk for colonic and extracolonic tumors

IMAGING • Innumerable colonic filling defects or ring shadows ± extraintestinal lesions • Adenomatous (± malignant) polyps in ○ Colon > stomach > duodenum > small bowel • 2 varied expressions of familial adenomatous polyposis (FAP) ○ FAP coli and Gardner syndrome • Small (80% < 5 mm) and usually sessile ○ May be widely scattered radiolucent filling defects ○ Polyps may carpet colon • Imaging tests: Double-contrast barium studies of colon and upper GI tract

(Left) Graphic shows innumerable small polyps and multifocal carcinomas representative of the colonic lesion types seen in patients with familial polyposis coli. (Right) Spot film from an aircontrast barium enema demonstrates multiple small radiolucent filling defects , which represent sessile adenomatous polyps along the sigmoid colonic mucosa.

(Left) Spot film from an aircontrast barium enema shows innumerable small polyps in the sigmoid colon. (Right) Gross pathology of a resected colon shows adenomatous polyps carpeting the colon surface. Note the pedunculated appearance of some polyps . While these adenomas generally start as sessile lesions, they may be drawn out onto stalks due to the peristaltic force of the bowel.

534

○ CT or MR (for abdominal tumors)

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • • •

Retained feces and food Lymphoid hyperplasia Metastases and lymphoma Pseudopolyps Primary pneumatosis coli

PATHOLOGY • Autosomal dominant trait (2/3 of cases) with high penetrance • Spontaneous mutations (1/3 of cases)

CLINICAL ISSUES • Mean age at diagnosis = 16 years; 95% have polyps by 35 years • Colon carcinoma by 34-43 years of age

Familial Polyposis and Gardner Syndrome

Abbreviations • Familial adenomatous polyposis (FAP) syndrome • Gardner syndrome may have the same genetic mutation ○ Distinction from FAP is largely semantic

Definitions • Autosomal dominant genetic disorder characterized by formation of innumerable colonic adenomatous polyps at young age and by increased risk for colonic and extracolonic tumors

IMAGING General Features • Best diagnostic clue ○ Innumerable colonic filling defects or ring shadows on barium enema • Location ○ Adenomatous polyps in – Colon > stomach > duodenum > small bowel • Size ○ Varies from pinpoint to > 1 cm • Morphology ○ Sessile or pedunculated polypoid lesions • Other general features ○ FAP: Rare, but it is the most common polyposis syndrome ○ 2 varied expressions of FAP: FAP coli and Gardner syndrome – Gardner syndrome □ Familial polyposis coli, osteomas, epidermoid (sebaceous) cysts □ Soft tissue tumors: Desmoid, mesenteric fibromatosis, lipoma □ Dental abnormalities; periampullary, duodenal, and thyroid carcinomas ○ Hundreds or thousands of polyps may carpet colon ○ FAP adenomas: Small (80% < 5 mm) and usually sessile ○ Extracolonic GI tract manifestations of FAP – Stomach □ Fundic gland polyps and adenomas in > 50% of cases – Duodenum: Adenomas of 2nd part, and periampullary in > 50% of cases □ Periampullary cancer: 2nd most frequent site of cancer outside colon, seen in 12% of FAP patients – Jejunum and ileum □ Adenomas, lymphoid hyperplasia in > 20% of cases ○ Associated with incidence of malignant CNS tumors

Radiographic Findings • Fluoroscopic-guided double contrast barium enema ○ Innumerable variably sized radiolucent filling defects ○ Carpet entire colon, especially rectosigmoid ○ May be widely scattered radiolucent filling defects • Double-contrast upper GI, small bowel ○ Multiple small filling defects (polyps) in stomach, duodenum, jejunum, and ileum

CT Findings • CECT ○ Useful for diagnosing and staging colon carcinomas – Colorectal cancers are often multiple – Look for nodal, peritoneal, hepatic metastases ○ Both desmoid and mesenteric fibromatosis: Higher attenuation than muscle • CT colonography can detect polyps but uncertain role in this setting (FAP)

Colon

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Double-contrast barium studies of colon and upper GI tract • CT or MR (for abdominal tumors)

DIFFERENTIAL DIAGNOSIS Retained Feces and Food • Filling defects in barium pool, mimicking polyps

Lymphoid Hyperplasia • Lymphoid follicles ○ Aggregates of lymphocytes in muscularis mucosae ○ Seen in 50% of barium studies for children, 13% for adults – Usually more prominent in right colon and distal small bowel • Barium studies ○ Innumerable small or tiny radiolucent nodules • Distinguished by clinical history and ill-defined borders of lymphoid follicle (submucosal)

Metastases and Lymphoma • Rarely as numerous as lesions in FAP • Metastases (e.g., malignant melanoma, breast, lung) ○ Smooth polypoid submucosal lesions of different sizes seen as filling defects that may mimic polyps • Lymphoma ○ Distribution: Stomach (51%), small bowel (33%), colon (16%), esophagus (< 1%) ○ Low-grade MALT lymphoma – Seen only in stomach due to Helicobacter pylori gastritis – Confluent nodules of varying size (filling defects) – May be indistinguishable from gastric polyps ○ Non-Hodgkin lymphoma – Small or bulky polypoid masses may mimic polyps – Smooth surface, broad base, sessile lesions ± central depressions or ulcerations – Bull's-eye sign: Polypoid mass with ulceration – Markedly thickened bowel wall and folds – Regional or widespread adenopathy seen

Pseudopolyps • Examples: Ulcerative colitis (common), granulomatous colitis • 2 types of pseudopolyps ○ Inflammatory pseudopolyps ○ Postinflammatory pseudopolyps • Inflammatory pseudopolyps 535

Colon

Familial Polyposis and Gardner Syndrome ○ Islands of elevated, inflamed, edematous mucosa surrounded by ulceration appear as pseudopolyps – Represent remnants of preexisting mucosa and submucosa rather than new growths ○ Natural progression of "collar-button" ulcers, which extend, interconnect, and mimic pseudopolyps • Postinflammatory pseudopolyps (mucosal overgrowth) ○ Regenerated mucosa results in polypoid lesions – Long and filiform or bush-like structure simulating villous adenoma; may be small and rounded ○ Seen during healing = postinflammatory pseudopolyps

Primary Pneumatosis Coli • Cystic intramural collections of gas in colon • Asymptomatic • Not due to ischemia

PATHOLOGY General Features • Etiology ○ FAP is inherited as autosomal dominant trait (2/3 of cases) ○ Occasionally due to spontaneous mutations (1/3 of cases) ○ High penetrance (affected patients will develop signs and symptoms) • Genetics ○ Truncating germline mutations of APC gene located on chromosome 5q • Associated abnormalities ○ Extracolonic malignancies associated with FAP – Duodenal ampullary carcinoma (12% lifetime risk) – Thyroid cancer – Childhood hepatoblastoma – Gastric carcinoma – CNS tumors (mostly medulloblastoma) ○ Extraintestinal manifestations: Gardner syndrome – Epidermoid cyst, lipoma, fibroma, desmoid tumors (329%), mesenteric fibromatosis, peritoneal adhesions, retroperitoneal fibrosis – Osteomas: Membranous bone (50%), mandible (80%) – Teeth: Odontoma, unerupted supernumerary teeth – Thyroid cancer: Papillary type more common in girls and young women

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Rectal bleeding and diarrhea (75% of cases) ○ Asymptomatic, pain, mucus discharge ○ Family history of colonic polyps (66-80% of cases)

Demographics • Age ○ Mean at diagnosis = 16 years; 95% have polyps by 35 years • Gender ○ M=F • Epidemiology ○ FAP affects 1 in 10,000-30,000 people in USA ○ Accounts for > 1% of colon cancers in USA

Natural History & Prognosis • Complications ○ Polyps: Malignant transformation – Colon > periampullary > stomach > jejunum ○ Colon carcinoma by 34-43 years of age – Almost all affected individuals will develop colon cancer unless they have prophylactic colectomy • Prognosis ○ Poor if abdominal desmoids, colonic carcinoma, or ampullary carcinoma develop

Treatment • Prophylactic total colectomy at ~ 20 years of age • Permanent ileostomy, Kock pouch • Continent endorectal pull-through pouch

DIAGNOSTIC CHECKLIST Consider • Check for family history: Colonic polyps, abdominal soft tissue tumors, and malignancies at young age

Image Interpretation Pearls • Gardner syndrome: Soft tissue tumors, bony osteomas, dental defects, and periampullary cancer

SELECTED REFERENCES 1.

Gross Pathologic & Surgical Features • Innumerable polyps carpeting colonic mucosa • Desmoid tumor ○ Confined to muscle, fascia, or deeply infiltrative ○ Size: 5-20 cm; firm and gritty texture; lack capsule ○ Cut surface: Glistening white + trabeculated

2.

3.

4.

Microscopic Features • Adenomas ○ Tubular, tubulovillous, and villous; ± atypia or mitosis – No difference from sporadic type of colonic polyps • Desmoid tumor ○ Spindle-shaped cells and dense bands of collagen

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5. 6. 7. 8.

Vitellaro M et al: Risk of desmoid tumours after open and laparoscopic colectomy in patients with familial adenomatous polyposis. Br J Surg. 101(5):558-65, 2014 Wood LD et al: Upper GI tract lesions in familial adenomatous polyposis (FAP): enrichment of pyloric gland adenomas and other gastric and duodenal neoplasms. Am J Surg Pathol. 38(3):389-93, 2014 Zhang Y et al: Adenomatous polyposis coli determines sensitivity to the EGFR tyrosine kinase inhibitor gefitinib in colorectal cancer cells. Oncol Rep. 31(4):1811-7, 2014 De Rosa M et al: Implication of adenomatous polyposis coli and MUTYH mutations in familial colorectal polyposis. Dis Colon Rectum. 52(2):268-74, 2009 Herráiz M et al: Recognition and management of hereditary colorectal cancer syndromes. Rev Esp Enferm Dig. 101(2):125-32, 2009 Mavrogiannis LA et al: Novel human pathological mutations. Gene symbol: APC. Disease: familial adenomatous polyposis. Hum Genet. 125(3):333, 2009 Spigelman AD: Extracolonic polyposis in familial adenomatous polyposis: so near and yet so far. Gut. 53(3):322, 2004 Macari M et al: Diagnosis of familial adenomatous polyposis using twodimensional and three-dimensional CT colonography. AJR Am J Roentgenol. 173(1):249-50, 1999

Familial Polyposis and Gardner Syndrome Colon

(Left) Spot film from an aircontrast barium enema shows innumerable small polyps, most within the range of 2-5 mm. Colonic polyps in familial polyposis can range in number from dozens to thousands, as in this case. (Right) Axial CECT in a 26-year-old man, unaware of the history of colon cancer in his family, shows numerous hepatic metastases from colon carcinoma.

(Left) Axial CECT in the same patient shows 1 of 3 colonic masses , all of which represent advanced colon cancer with invasion through the wall, regional lymphadenopathy, and hepatic metastases. (Right) Axial CECT in the same patient shows a large rectal mass with extension through the wall, infiltration of the perirectal fat, and metastases to regional nodes . The patient had presented with rectal bleeding and weight loss.

(Left) Upper GI series spot film shows the stomach carpeted with small polyps, all fairly small and uniform in size. While these resemble hyperplastic polyps radiographically, this patient has familial polyposis with adenomatous polyps that have potential for malignant degeneration. (Right) Upper GI series spot film in a patient with familial polyposis and Gardner syndrome shows several adenomatous polyps in the duodenum .

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Colon

Familial Polyposis and Gardner Syndrome

(Left) This 37-year-old man had minimal contact with physicians and presented with rectal bleeding and weight loss. CT shows multiple liver metastases . (Right) CT in the same case shows multiple liver metastases and a small mass at the duodenal ampulla , subsequently proven to be an adenoma.

(Left) CT in the same case shows a small bowel intussusception , likely induced by small bowel polyps (not visualized). (Right) CT in the same case shows a mass in the buttocks that is higher in attenuation than adjacent muscle and likely represents a desmoid tumor or fibromatosis.

(Left) CT in the same case shows a mass in the sigmoid colon, subsequently proved to be an adenocarcinoma. (Right) Following the abdominal CT in this patient, a CT section through the facial bones reveals cortical thickening and osteomas . All of the highlighted findings are typical features of Gardner syndrome.

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Familial Polyposis and Gardner Syndrome Colon

(Left) This 19-year-old woman had known FAP and had a total colectomy. She later presented with a hard, palpable abdominal mass. Axial CECT images show evidence of the prior colectomy with an ileal pouch . There is a large mass in the right rectus muscle that proved to be a desmoid tumor within an incision site. (Right) Axial CT in the same case shows a more subtle mass at the base of the mesentery, also proven to represent desmoid or aggressive fibromatosis.

(Left) This young woman, presenting with weight loss and anemia, had no family history of colon cancer. CT shows multiple liver metastases . (Right) CT in the same case shows a mass within the ascending colon, subsequently proven to represent colon cancer.

(Left) Another CT section in this case shows a tumor in the recto-sigmoid colon , and extensive spread to the regional nodes . (Right) CT in the same case shows the rectal cancer with extensive infiltration into the perirectal tissues. As with this patient, some cases of FAP lack a family history and may result from spontaneous genetic mutation.

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Colon

Appendiceal Tumors KEY FACTS

TERMINOLOGY • Primary malignant neoplasm of appendix ○ Mucinous cystadenocarcinoma (90%) ○ Colonic-type adenocarcinoma (10%) ○ Lymphoma (< 1%) ○ Carcinoid (common, usually incidental at appendectomy)

IMAGING • Round or oval, cystic or solid, mass near tip of cecum • Mucocele ○ RLQ soft tissue mass with curvilinear mural calcification on radiography is highly suggestive ○ Ovoid cystic mass ± internal echoes (septations) on US • Mucinous tumor: RLQ cystic mass, usually > 2 cm ○ Mucinous type has strong propensity to form mucocele ○ May have curvilinear calcification in wall ○ Mucinous cystadenocarcinoma is most common cause of pseudomyxoma peritonei • Lymphoma: Cylindrical, soft tissue density mass

(Left) Axial CECT shows an oval, well-encapsulated, cystic mass arising from the tip of the cecum in this 62-year-old man with mucinous carcinoma of the appendix. With imaging alone, a benign mucocele may not be distinguished from a mucinous carcinoma. (Right) Axial CECT in an 80-year-old man with pseudomyxoma peritonei due to ruptured mucinous carcinoma of the appendix shows the classic scalloped appearance of the surface of the liver due to peritoneal gelatinous metastases.

(Left) Axial CECT in a 60-yearold woman with chronic RLQ pain shows a hypodense mass with a typical appearance of liver metastasis. (Right) Axial CT in the same case shows a thick-walled appendix with a calcified appendicolith within its lumen and infiltration of adjacent fat . While these findings mimic those of appendicitis, there is much more soft tissue density within the wall than would be expected with simple appendicitis. Liver metastases suggest the correct diagnosis of appendiceal carcinoma.

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○ Cannot distinguish from carcinoma on CT • Carcinoid ○ Rarely diagnosed clinically or by imaging prior to appendectomy

TOP DIFFERENTIAL DIAGNOSES • Mucocele of appendix (other etiologies) ○ Nonneoplastic forms rarely exceed 2 cm in diameter • Appendicitis (abscess) ○ More inflammatory changes are seen ○ No liver or peritoneal metastases • Ovarian cystic mass ○ Identify right ovary as source or separate from mass

CLINICAL ISSUES • Appendiceal tumors are found in 1% of appendectomies (usually carcinoid) • Appendiceal tumors constitute 0.5% of intestinal neoplasms

Colonic Metastases and Lymphoma

IMAGING • Best imaging tools: CT, MR, barium enema • Protocol advice ○ Intravenous contrast for CT or MR ○ Double contrast barium enema

TOP DIFFERENTIAL DIAGNOSES • Adenocarcinoma ○ Short, focal, "apple core" lesion < 10 cm in length ○ More likely to cause colonic obstruction than submucosal lymphoma or mets • Colonic Kaposi sarcoma • Ileocolic tuberculosis • Gastrointestinal stromal tumor

PATHOLOGY • Metastatic spread from melanoma or primary tumor of stomach, lung, or breast (rarely, other cancers)

○ Gastric cancer may directly invade transverse colon along gastrocolic ligament • Lymphoma may arise from and be limited to colon

Colon

KEY FACTS

CLINICAL ISSUES • Most common signs/symptoms: Rectal bleeding, symptoms of obstruction, especially if intussusception is present • 50% 5-year survival rate for patients with primary colonic lymphoma • Prognosis is poor for patients with metastases to colon from melanoma, breast, lung, or gastric cancer

DIAGNOSTIC CHECKLIST • Consider lymphoma for bulky mass with aneurysmal dilatation of lumen and no colonic obstruction • "Serrated" edge of transverse colon (on barium enema) may indicate gastric cancer invading gastrocolic ligament

(Left) Axial CECT in a 67-yearold man presenting with 3 months of intermittent rectal bleeding and clinical symptoms of obstipation shows a bulky enhancing mass involving the rectosigmoid colon, with no evidence of colonic obstruction. (Right) Axial CECT in the same patient reveals an enhancing perirectal nodal metastasis . The patient had a subsequent endoscopic biopsy of the mass, which identified a non-Hodgkin lymphoma.

(Left) Axial CECT in a 71-yearold man with known lung carcinoma presenting with LLQ pain and a palpable mass demonstrates a large heterogeneously enhancing mass involving the descending colon . This was a colonic metastasis. (Right) Axial CECT in a 68-year-old man with weight loss and RLQ pain demonstrates a bulky ileocecal mass with smooth margins . Note the oral contrast filling the lumen of the cecum , indicating the lack of obstruction. Endoscopic biopsy revealed a high-grade B-cell lymphoma.

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SECTION 8

Spleen

Introduction and Overview Imaging Approach to the Spleen

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Normal Variants and Artifacts Accessory Spleen

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Congenital Asplenia and Polysplenia

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Infection Splenic Infection and Abscess

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Degenerative Splenomegaly and Hypersplenism

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Vascular Disorders Splenic Infarction

562

Trauma Splenic Trauma

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Splenosis

570

Benign Neoplasms Splenic Cyst

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Primary Splenic Tumors

574

Malignant Neoplasms Splenic Metastases and Lymphoma

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Spleen

Imaging Approach to the Spleen

Embryology, Anatomy, and Physiology The spleen develops from the dorsal mesogastrium and usually rotates to the left, becoming fixed in the left subphrenic location by peritoneal reflections linking it to the diaphragm, abdominal wall, stomach (gastrosplenic ligament), and kidney (splenorenal ligament). It usually develops as 1 "fused" mass of tissue, but variations are common. One or more accessory spleens are found in up to 30% of the general population, usually small spherical structures near the splenic hilum. These can enlarge, especially following splenectomy, and may simulate a neoplastic mass or cause recurrence of hematologic disease. The spleen may be congenitally absent (asplenia) or have many unfused components (polysplenia). These are rare splenic anomalies and are associated with cardiovascular anomalies, situs inversus, and other anomalies, often with serious and even life-threatening consequences. The spleen is rarely on a long mesentery and may be found in any abdominal or pelvic location ("wandering spleen"), placing it at risk for trauma and torsion with infarction. The spleen is the largest lymphatic organ, the size of which varies among individuals and even in the same person by blood volume, state of nutrition and hydration. The usual volume range is 100-250 cm³, with a mean of 150 cm³. A calculated splenic index (length x width x breadth) over 480 cm³ is considered splenomegaly. The average length is up to 12 cm, with a width and breadth of 7 and 4 cm, respectively.

Imaging Issues The spleen has a unique histology, consisting of the red and white pulp, which directly affects its appearance on imaging exams. The white pulp is the lymphoid tissue and the red is composed of the vascular tissue and splenic cords (plates of cells and sinusoids). Because of its vascularity, the red pulp enhances rapidly, giving the spleen a very heterogeneous pattern of enhancement on arterial phase enhanced CT or MR imaging. This may be mistaken for splenic pathology but is a transient phenomenon not evident on unenhanced or later phases of enhanced imaging. CT is the imaging modality of choice for the evaluation of the spleen in the acute setting (trauma or pain). MR can be additive in evaluating splenic masses and some metabolic diseases (e.g., hemochromatosis). The spleen has a relatively long T1 and T2 relaxation time. This results in its appearing somewhat hypointense compared to the liver on T1WI and hyperintense on T2WI. With iron deposition, the spleen may show a dramatic loss in signal.

Approach to the Abnormal Spleen Splenomegaly is a very common finding and may result from numerous causes, usually grouped into 5 general etiologies, including congestion, hematologic, inflammatory-infectious , tumor, or infiltrative. Given its function as a blood filter, it is not surprising that the spleen is a frequent site of metastases on postmortem examination of patients who have died from cancer. However, with the exception of leukemia and lymphoma, it is uncommon to make an imaging diagnosis of splenic metastasis.

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Many splenic neoplasms are benign, either hemangiomas or lymphangiomas, but these have overlapping imaging features and a specific diagnosis is rarely possible. One of the most common focal splenic lesions is the splenic cyst. It is not possible to distinguish the primary congenital (epithelial-lined) cyst from the acquired cyst by imaging, with the latter resulting from prior infarction, infection, or trauma. These are rarely of clinical importance. Multiple lesions within the spleen are most typically the result of a granulomatous process, which may be either infectious (e.g., histoplasmosis, TB) or noninfectious (sarcoidosis). Splenic granulomata commonly calcify. The pancreatic tail usually inserts into the splenic hilum through the splenorenal ligament. Inflammatory or neoplastic conditions affecting the pancreatic tail can easily invade the splenic parenchyma, resulting in intrasplenic pseudocyst, for instance. Conversely, splenic tumors or an accessory spleen may mimic a pancreatic tail mass. Splenic infarction is a relatively common cause of acute left upper quadrant pain. It appears as a sharply defined, often wedge-shaped zone of minimal enhancement abutting the splenic capsule. Patients at risk for infarction include those with sickle cell disease and those with cardiovascular conditions, such as atrial fibrillation. Patients with left ventricular assist devices are especially prone to embolic infarction of the spleen. The spleen is often injured in blunt and penetrating trauma. Most children and adults with splenic lacerations will recover without surgery, but the presence of active extravasation (evident on CT) or clinical instability may demand intervention, either surgery or transcatheter embolization. Splenosis is the peritoneal implantation of splenic tissue that may follow traumatic rupture of the spleen. This may be mistaken for polysplenia or peritoneal implants of tumor (carcinomatosis). The history of trauma, absence of a normal spleen, and enhancement characteristics identical to spleen usually allow accurate diagnosis.

Differential Diagnosis Splenomegaly Common • Cirrhosis with portal hypertension • Congestive heart failure • AIDS • Splenic metastases and lymphoma • Hemoglobinopathies • Leukemia • Sarcoidosis • Mononucleosis • Myeloproliferative disorders • Splenic trauma Less common • Splenic tumors (primary) • Systemic infection and abscesses • Splenic vein occlusion • Splenic infarction • Malaria • Collagen vascular diseases: Rheumatoid arthritis, scleroderma, dermatomyositis, polyarteritis nodosa • Storage diseases: Amyloidosis, glycogen storage disease • Peliosis

Imaging Approach to the Spleen

Less common • Echinococcal (hydatid) cyst • Healed abscess Solid Splenic Mass or Masses Common • Splenic trauma • Splenic infarction • Splenic metastases and lymphoma • Perfusion artifact Less common • Sarcoidosis • Splenic infection and abscess • Splenic tumors

• Peliosis Cystic Splenic Mass Common • Acquired or congenital splenic cyst • Splenic trauma • Splenic infarction

Spleen

Multiple Splenic Calcifications Common • Histoplasmosis • Tuberculosis • Arterial calcification and aneurysm • Pneumocystis jiroveci • Splenic infarction • Splenic cyst

Less common • Splenic metastases and lymphoma • Splenic infection and abscess • Splenic tumors • Pancreatic pseudocyst Diffuse Increased Attenuation, Spleen Common • Hemochromatosis • Splenic infarction: Sickle cell anemia Less common • Opportunistic infection • Thorotrast

(Left) Arterial phase axial CECT shows a very heterogeneous spleen caused by rapid enhancement of the vascular sinusoids (red pulp). This should not be mistaken for a pathologic process. (Right) Axial CECT during the venous phase shows the spleen with a homogeneous appearance.

(Left) Axial T1WI MR (A) shows the normal spleen as slightly hypointense relative to liver. On T2WI MR (B), the normal spleen is slightly hyperintense to liver. (Right) Axial CECT shows a "mass" in the pancreatic tail that is isodense to the spleen and represents an accessory spleen. This could be mistaken for a primary pancreatic mass, such as a neuroendocrine tumor.

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Spleen

Imaging Approach to the Spleen

Gastric impression

Stomach Renal impression

Prominent medial lobulation

Kidney

Stomach

Gastrosplenic ligament

Spleen Splenic artery

Splenorenal ligament Splenic vein Splenocolic ligament

(Top) Graphic shows the medial surface of the spleen and representative axial sections at 3 different levels. The spleen is of variable shape and size, even within the same individual, varying with states of nutrition and hydration. The medial surface is often quite lobulated as it is interposed between the stomach and the kidney. (Bottom) The splenic artery and vein course along the body of the pancreas, entering and exiting the spleen via the splenorenal ligament. The tail of the pancreas also inserts into the splenic hilum through the splenorenal ligament. The gastrosplenic ligament carries the short gastric and left gastroepiploic vessels to the stomach and upper portion of the spleen.

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Imaging Approach to the Spleen Spleen

(Left) Axial CECT in a patient with non-Hodgkin lymphoma shows numerous enlarged upper abdominal lymph nodes . Splenomegaly is a common abnormality and can be caused by congestion, hematologic disorders, inflammatory/infectious conditions, tumors, or infiltrative processes. (Right) Axial CECT in a different case of splenomegaly caused by congestion secondary to cirrhosis and portal hypertension shows the recanalized umbilical vein .

(Left) Axial CECT shows 2 splenic lesions. The larger lesion has water density contents and thin, sharp walls, typical of simple cyst. The smaller lesion has nodular walls and higher density contents, suggestive of splenic lymphangioma. (Right) In this patient with non-Hodgkin lymphoma the spleen is markedly enlarged with heterogeneous, hypoattenuating, more discrete tumor foci . Lymphomatous infiltration is also present within the adrenal gland and nodes throughout the abdomen.

(Left) Axial CECT in a patient with heart failure and abdominal pain shows a ventricular assist device and wedge-shaped regions of nonenhancing splenic parenchyma that extend to the capsular surface, characteristic of acute splenic infarctions. (Right) Axial CECT in a patient injured in a motor vehicle crash shows a sentinel clot adjacent to the spleen and a large hemoperitoneum . Note the active extravasation of blood that is isodense to enhanced vessels.

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Spleen

Accessory Spleen KEY FACTS

TERMINOLOGY • Benign ectopic splenic tissue of congenital origin

IMAGING • Most splenules located in or near splenic hilum or ligaments ○ 20% are near or within pancreatic tail and can mimic pancreatic neuroendocrine tumor ○ May also be in diaphragmatic, pararenal, and gastric sites • NECT and CECT: Same enhancement and attenuation as normal spleen ○ Isodense to main spleen on noncontrast images ○ Characteristic serpiginous enhancement on arterial phase ○ Homogeneous enhancement on venous/delayed images • MR: T1WI hypointense and T2WI hyperintense ○ Follows appearance of spleen on all sequences ○ DWI: Isointense to spleen with similar ADC values • Nuclear medicine: Technetium (Tc-99m) sulfur colloid or Tc99m heat-damaged red blood cell (RBC) scan

(Left) Axial CECT shows a small spherical accessory spleen near the splenic hilum. Note the foci of calcification from histoplasmosis in the main and accessory spleen. This appearance is so characteristic as to require no additional evaluation. (Right) Axial CECT demonstrates a large mass abutting the pancreatic tail and the splenic hilum. The mass was thought to be a neuroendocrine tumor and was resected. Note that the mass is isodense to the spleen. The mass was found to be a splenule at surgery.

(Left) Axial CECT shows an enlarged spleen due to portal hypertension in this patient with cirrhosis. Note the prominent accessory spleen as well as the varices . An accessory spleen may enlarge in parallel with the main spleen. (Right) Axial CECT shows a hypervascular mass within the pancreatic tail that mimics an islet cell tumor. A heat-damaged red blood cell scan (not shown) proved this to be an accessory spleen. Masses in the splenic hilum may arise from or involve the tail of the pancreas or spleen.

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○ Functional uptake in splenic tissue differentiates splenule from other masses • Rare complication: Torsion of splenule as cause of abdominal pain in children or young adults

TOP DIFFERENTIAL DIAGNOSES • • • • •

Splenosis Polysplenia Peritoneal metastases and lymphoma Visceral mass (especially pancreatic neuroendocrine tumor) Splenic artery aneurysm or pseudoaneurysm

PATHOLOGY • Congenital: Failure of some embryonic splenic buds to unite within dorsal mesogastrium

CLINICAL ISSUES • Asymptomatic (vast majority of cases) • In absence of complications (which are extraordinarily rare), no treatment or intervention

Accessory Spleen

Synonyms • Splenule, splenunculus

DIFFERENTIAL DIAGNOSIS

Definitions

Splenosis

• Benign ectopic splenic tissue of congenital origin

• Usually result of trauma; portions of disrupted spleen implant anywhere including abdomen, pelvis, and chest

IMAGING General Features • Best diagnostic clue ○ Small, round, well-marginated nodule in left upper quadrant with same enhancement as normal spleen • Location ○ In or near splenic hilum or ligaments (most cases) – 20% are near or within pancreatic tail – Usually left upper quadrant, above renal pedicle – Rarely in diaphragmatic, pararenal, and gastric sites ○ Single splenule in vast majority of patients – 1 splenule (88%), 2 splenules (9%), > 2 splenules (3%) – Multiple splenules usually clustered in 1 location • Size ○ Varies from 1 mm to a few cm, usually < 2.5 cm

CT Findings • Same enhancement as normal spleen ○ Isodense to main spleen on noncontrast images ○ Serpiginous enhancement on arterial phase ○ Homogeneous enhancement on venous/delayed images • Most commonly located near splenic hilum or ligaments • 2nd most common location is pancreatic tail ○ Usually < 3 cm medial to pancreatic tail ○ Most often along dorsal surface of pancreas ○ Incompletely surrounded by pancreatic parenchyma • Rare: Torsion of splenule as cause of abdominal pain ○ Nonenhancing mass with surrounding hemorrhage ○ Whorl sign (twisted vascular pedicle) leading to splenule

MR Findings • T1WI hypointense and T2WI hyperintense ○ Follows appearance of spleen on all sequences • DWI: Isointense to spleen with similar apparent diffusion coefficient (ADC) values ○ Pancreatic neuroendocrine tumors usually hyperintense on DWI with lower ADC values • Superparamagnetic iron oxide particles (SPIO) contrast media taken up by splenic tissue (but not tumor)

Nuclear Medicine Findings • Technetium (Tc-99m) sulfur colloid or Tc-99m heatdamaged red blood cell (RBC) scan ○ Functional uptake in splenic tissue differentiates splenule from other masses ○ Tc-99m heat-damaged RBC scan preferred due to higher specificity and better target to background • PET CT ○ FDG-avid mass can mimic tumor

Imaging Recommendations

Spleen

○ Multiphase CT followed by Tc-99m heat-damaged RBC scan in equivocal cases

TERMINOLOGY

Polysplenia • Congenital disorder with multiple small spleens, bilateral left-sidedness of viscera, and cardiovascular anomalies

Peritoneal Metastases and Lymphoma • e.g., omental or peritoneal metastases

Visceral Mass • Splenules commonly mistaken for pancreatic neuroendocrine tumors • Splenules also mistaken for adrenal, gastric, or renal tumors

Splenic Artery Aneurysm or Pseudoaneurysm • Bright homogeneous enhancement on arterial phase

PATHOLOGY General Features • Etiology ○ Congenital: Failure of some embryonic splenic buds to unite within dorsal mesogastrium

Gross Pathologic & Surgical Features • Structurally normal splenic tissue

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic (vast majority of cases) • Other signs/symptoms ○ May torse, rupture, and bleed (very rare) ○ May cause recurrence of hematologic disease (e.g., lymphoma) following prior splenectomy

Demographics • Epidemiology ○ Incidence: 10-30% of patients at autopsy

Treatment • In absence of complications (which are extraordinarily rare), no treatment or intervention • Surgical resection: Only in setting of complications, recurrence of lymphoma, or hypersplenism

DIAGNOSTIC CHECKLIST Consider • Accessory spleen is common and can be mistaken for tumor

SELECTED REFERENCES 1.

Coquia SF et al: Intrapancreatic accessory spleen: possibilities of computed tomography in differentiation from nonfunctioning pancreatic neuroendocrine tumor. J Comput Assist Tomogr. ePub, 2014

• Best imaging tool 549

Spleen

Asplenia and Polysplenia KEY FACTS

TERMINOLOGY • Complex inherited syndromes associated with absence or multiplicity of spleens as well as many other anomalies

IMAGING • Asplenia (ASP) syndrome: Right isomerism or bilateral right-sidedness ○ Absent spleen in virtually all patients ○ Congenital heart disease in ~ 100% of patients ○ Bilateral trilobed lungs ○ Malrotation in most patients ○ Aorta and inferior vena cava (IVC) are frequently ipsilateral (usually right side) • Polysplenia (PSP) syndrome: Left isomerism or bilateral left-sidedness ○ Usually multiple spleens, but may have single normal spleen ○ Increased risk of complex cardiac anomalies, although less common with PSP than ASP

(Left) Coronal volumerendered CECT in a patient with polysplenia (PSP) syndrome demonstrates multiple spleens in the left upper quadrant. The multiple spleens in PSP are typically in the left abdomen, but can rarely be on the right. (Right) Axial CECT in the same patient demonstrates a markedly dilated azygous vein .

(Left) Axial CECT in the same patient again demonstrates multiple spleens and a dilated azygous vein to the right of the aorta. Azygous continuation of the inferior vena cava (IVC) is a very common abnormality in PSP syndrome. (Right) Axial CECT in the same patient demonstrates malrotation of the bowel, with the small bowel abnormally located in the right abdomen and the entirety of the colon in the left abdomen. Malrotation is quite common with both asplenia (ASP) and PSP syndromes.

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○ IVC interruption with azygos continuation very common ○ Bilateral bilobed lungs ○ Truncated/short pancreas or agenesis of dorsal pancreas – Increased incidence of diabetes and pancreatitis ○ Intestinal malrotation is seen in most patients ○ Liver often midline with range of biliary abnormalities ○ Aorta usually located to left of midline

TOP DIFFERENTIAL DIAGNOSES • Splenosis • Accessory spleen • Splenectomy

CLINICAL ISSUES • ASP: Newborn or infant presentation due to cardiac disease with poor prognosis and early mortality ○ risk of sepsis due to lack of spleen • PSP: Infant or adult presentation with better prognosis due to lesser incidence of cardiac disease

Asplenia and Polysplenia

Abbreviations • Asplenia (ASP), polysplenia (PSP)

Synonyms • Heterotaxy syndromes • ASP: Asplenia syndrome, Ivemark syndrome, bilateral rightsidedness • PSP: Polysplenia syndrome, bilateral left-sidedness

Definitions • Complex inherited syndromes associated with absence (ASP) or multiplicity (PSP) of spleens, as well as many other anomalies

Associated Syndromes • Heterotaxy: Abnormal embryologic placement of thoracoabdominal structures across right-left axis of body • Situs solitus: Normal placement of thoracoabdominal organs in right-left axis • Situs inversus: Reversal of normal positions of thoracoabdominal organs across right-left axis (mirrorimage of situs solitus) • Situs ambiguus (heterotaxy syndrome): Abnormal placement of thoracoabdominal structures without situs inversus

IMAGING General Features • Best diagnostic clue ○ ASP: Absence of spleen, abdominal aorta and inferior vena cava (IVC) on same side (usually right), and bilateral distribution of right-sided viscera ○ PSP: Multiple small spleens, intrahepatic interruption of IVC with continuation of azygos vein, bilateral distribution of left-sided viscera • PSP ○ Number of spleens varies from 2 to 16 • Key concepts ○ ASP syndrome: Right isomerism or bilateral rightsidedness – Situs ambiguus and bilateral right-sidedness; no fixed set of findings, abnormalities exist across a spectrum – Spleen □ Absent spleen in virtually all patients – Cardiovascular □ Congenital heart disease in ~ 100% of patients □ Total anomalous pulmonary venous return (almost 100%), endocardial cushion defect (85%), single ventricle (51%), transposition of great vessels (58%), pulmonary stenosis or atresia (70%), dextrocardia (42%), mesocardia, ventricular septal defect, single atrioventricular valve, bilateral superior vena cava (SVC) □ Aorta and IVC are frequently ipsilateral (usually right side) – Pulmonary □ Abnormal distribution of lobes with bilateral trilobed lungs – Gastrointestinal

□ Malrotation in most patients with ASP □ Other associations: Imperforate anus, ectopic liver, annular pancreas, esophageal varices, gallbladder agenesis, Hirschsprung disease, and duplication or hypoplasia of stomach – Genitourinary □ Horseshoe kidney, bilobed urinary bladder, hydroureter, double collecting system, cystic kidney – Miscellaneous □ Cleft palate, cleft lip, fused or horseshoe adrenal gland, absent left adrenal gland, scoliosis, bicornuate uterus, single umbilical artery, lumbar myelomeningocele ○ PSP syndrome: Left isomerism or bilateral left-sidedness – Situs ambiguus and bilateral left-sidedness: No fixed set of findings and abnormalities exist across a spectrum – Spleen □ Usually multiple spleens in left upper quadrant, but some cases may have single normal spleen □ Isolated reversal of splenic position (in right abdomen) common – Cardiovascular □ Increased risk of complex cardiac anomalies, although less common with PSP than with ASP, accounting for better long-term survival □ Transposition of great vessels (13%), double outlet right ventricle (13%), pulmonary valvular stenosis (23%), subaortic stenosis, or atresia □ IVC interruption with azygos vein continuation is 2nd most common abnormality (65%) after multiple spleens □ Aorta usually located to left of midline – Pulmonary □ Abnormal distribution of lobes with bilateral bilobed lungs □ Only seen in 55% of patients – Gastrointestinal □ Truncated/short pancreas or agenesis of dorsal pancreas with increased incidence of diabetes and pancreatitis □ Intestinal malrotation seen in most patients with PSP and may range from nonrotation to complete malrotation □ Liver often midline with range of biliary tree abnormalities (absent gallbladder, biliary atresia) □ Isolated reversal of stomach position common □ Other associations: Esophageal or duodenal atresia, tracheoesophageal fistula, semiannular pancreas, gastric duplication, short bowel – Genitourinary □ Renal agenesis, renal and ovarian cysts

Spleen

TERMINOLOGY

Radiographic Findings • Radiography ○ ASP – Heart: Mesocardia or dextrocardia – Right-sided bronchial pattern and minor fissure may be seen bilaterally – Superior mediastinal widening (due to bilateral SVC)

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Spleen

Asplenia and Polysplenia

– Both pulmonary arteries anterior to trachea on lateral chest film ○ PSP – Frontal view: Paratracheal soft tissue prominence (dilated azygos/hemiazygos) mimicking mass – Chest lateral view: Both pulmonary arteries posterior to trachea and absence of IVC shadow

CT Findings • ASP ○ Absence of spleen ○ Situs abnormalities: Liver, gallbladder, stomach, bowel, heart, trilobed lungs ○ IVC and abdominal aorta lie on same side of spine (usually on right side with aorta lying posteriorly) • PSP ○ Multiple splenules in right or left upper quadrants – ± asymmetric liver and midgut malrotation ○ Enlarged azygos or hemiazygos vein with azygous continuation of IVC – Absence of IVC between renal and hepatic veins with independent drainage of hepatic veins into right atrium

Imaging Recommendations • Best imaging tool ○ CECT or MR can demonstrate position and number of spleen(s), as well as other visceral organ abnormalities associated with heterotaxy syndromes

DIFFERENTIAL DIAGNOSIS Splenosis • Scattered splenic tissue throughout abdomen usually seen in setting of traumatic splenectomy • Multiple small implants ranging in size from few mm to few cm; should enhance similarly to normal splenic tissue • No other associated anomalies

Accessory Spleen • Normal embryologic variant usually found near splenic hilum along course of splenic vessels • Identical to normal splenic tissue on any phase of enhancement • No other associated anomalies

Splenectomy • No splenic visualization after surgical splenectomy • No other associated anomalies

PATHOLOGY General Features • Etiology ○ Uncertain etiology, but may be associated with gene mutations (CFC1 gene, SHROOM3 gene, etc.) – Altered timing in development of embryonic body curvature leads to visceroatrial situs abnormalities □ ASP: Delayed embryonic body curvature □ PSP: Accelerated embryonic body curvature – Pressure of adjacent structures may interfere with splenic blood supply leading to development of ASP/PSP 552

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ ASP – Most commonly present with cardiopulmonary disease (83%), including cyanosis as neonates or in infancy – Patients are prone to overwhelming sepsis (especially postoperatively) due to lack of spleen – Bowel obstruction (17%) due to malrotation ○ PSP – 10-15% may not present clinically until adulthood – Often present with cardiac disease, including heart murmur, congestive heart failure, occasional cyanosis, heart block – Jaundice due to biliary atresia or other biliary abnormalities – Abdominal pain related to bowel obstruction or intestinal ischemia related to malrotation

Demographics • Age ○ ASP: Newborn or infant presentation ○ PSP: Infant or adult • Gender ○ ASP: M > F (2:1) ○ PSP: F > M • Epidemiology ○ ASP: 1 in 40,000 live births ○ Heterotaxia syndromes: 1 in 10,000

Natural History & Prognosis • ASP: Very poor prognosis ○ Mortality rate: Prognosis depends on extent of cardiac abnormalities, but only 20% survive to age of 16 • Polysplenia: Fair prognosis, better than asplenia ○ Mortality rate: 50-60% mortality in 1st year, 25% of patients live up to 5 years, and 10% survive to mid adolescence

Treatment • ASP: Prophylactic antibiotics (not needed in PSP) • Surgical correction of cardiac disease or malrotation in either ASP or PSP

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Left liver lobe can simulate spleen on US leading to missed diagnosis of ASP • Differentiate PSP from accessory spleens and splenosis

SELECTED REFERENCES 1.

Tawfik AM et al: Polysplenia syndrome: a review of the relationship with viscero-atrial situs and the spectrum of extra-cardiac anomalies. Surg Radiol Anat. 35(8):647-53, 2013

Asplenia and Polysplenia Spleen

(Left) Axial CECT in a patient with PSP syndrome demonstrates multiple spleens located in the right upper quadrant and situs inversus. Note the reversed positions of the liver and stomach. (Right) Axial CECT in the same patient demonstrates an abnormal right-sided stomach . Note that the IVC is normally located on the right. The majority of the small bowel is on one side of the abdomen, in keeping with malrotation.

(Left) Axial CECT in a patient with PSP syndrome shows dextrocardia and a left-sided IVC . (Right) Axial CECT in the same patient shows complete abdominal situs inversus with an otherwise normal-appearing stomach and liver on the right-hand side. Note the left-sided IVC .

(Left) Axial CECT in the same patient shows multiple splenules in the right upper quadrant along with abdominal situs inversus. (Right) Axial CECT in the same patient shows multiple spleens , situs inversus, and cystic disease of the kidneys . This patient was 35 years old (patients with PSP are much more likely to reach adulthood than ASP).

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Spleen

Splenic Infection and Abscess KEY FACTS

• Pyogenic abscess on CECT ○ Low-attenuation complex fluid collection ± air-fluid levels ○ Internal gas bubbles, which although uncommon, are very specific for splenic abscess ○ Multiloculated appearance seen with liver abscesses possible, but less common with splenic abscess ○ May extend to subcapsular location and may rarely cause splenic rupture with generalized peritonitis • Fungal microabscesses on CECT ○ Multiple small hypodense lesions measuring a few mm ○ Multiple punctate splenic calcifications after treatment • Echinococcal (hydatid) cyst on CECT ○ Complex cyst with multiple low density "daughter" cysts and thick, enhancing wall ("cyst within a cyst") ○ Serpiginous, linear densities within cyst due to collapsed parasitic membranes (water lily sign)

(Left) Axial CECT shows a multiloculated mass within the spleen that proved to be a pyogenic abscess. Such large abscesses are unusual in the spleen, especially in the absence of prior splenic infarction. (Right) Axial CECT in a patient with a recent history of traumatic injury to the spleen and a new fever demonstrates a rim-enhancing fluid collection with an airfluid level , consistent with a splenic abscess. The patient was treated with percutaneous drainage and antibiotics.

(Left) Axial CECT in a patient with HIV/AIDS who was admitted with fever and weight loss demonstrates microabscesses throughout the spleen. The patient deteriorated rapidly, and multiple tuberculous abscesses were identified at autopsy. (Right) Axial CECT shows a splenic hydatid cyst with additional similar lesions in the liver and peritoneal cavity , many of which have calcified walls. This patient had a prior rupture of a hepatic hydatid cyst with diffuse spread throughout the abdomen.

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○ May demonstrate thick peripheral calcification or internal wavy, curvilinear calcification in chronic setting

IMAGING

TOP DIFFERENTIAL DIAGNOSES • • • •

Splenic infarct Splenic tumor Splenic trauma Infiltrating disorders

PATHOLOGY • Multiple different causes for splenic pyogenic abscesses ○ Generalized septicemia, septic emboli (usually in setting of endocarditis with mitral &/or aortic valve vegetations), or secondary infection of traumatic splenic hematoma or infarct • Most fungal microabscesses occur in setting of immunosuppression, HIV/AIDS, or hematologic disorders • Echinococcal infections occur due to infection with tapeworm (Echinococcus granulosus)

Splenic Infection and Abscess

Definitions • Splenic abscess: Collection of liquefied pus within splenic parenchyma

IMAGING General Features

MR Findings • Fluid signal at center of lesion (hyperintense on T2WI and hypointense on T1WI) with peripheral enhancement on T1WI C+ images • Old healed/treated fungal microabscesses may show blooming artifact on GRE sequences due to calcification

Ultrasonographic Findings

• Best diagnostic clue ○ Rounded low-attenuation complex fluid collection with mass effect • Location ○ Variable: May be located anywhere within splenic parenchyma • Size ○ Variable: Typically 3-5 cm for pyogenic abscesses; < 1.5 cm for microabscesses (often fungal) • Morphology ○ Rounded cystic mass with irregular borders – May have multiple locules similar to cluster sign of hepatic pyogenic abscess – Internal septations common – Exerts mass effect on splenic capsule

• Grayscale ultrasound ○ Pyogenic abscess – Hypoechoic or anechoic mass with internal septations and low-level echoes representing pus or debris □ Rarely, atypical splenic abscess appears echogenic – May have variable degrees of posterior acoustic enhancement, depending on cyst contents – "Dirty" shadowing and ring-down artifact suggest presence of gas within collection □ US is much less sensitive for ectopic gas than CT ○ Fungal microabscesses – "Target" or bull's-eye appearance similar to hepatic microabscesses • Color Doppler ○ Pyogenic and fungal abscesses typically show no internal color flow vascularity

Radiographic Findings

Imaging Recommendations

• Radiography ○ Very rarely gas bubbles within abscess may be visualized on radiographs ○ Often associated with left lower lobe atelectasis and left pleural effusion on chest radiograph

• Best imaging tool ○ CECT

CT Findings • Pyogenic abscess ○ Low-attenuation (20-40 HU) complex fluid collection ± air-fluid levels – May have an enhancing peripheral rim, but not as conspicuous as generally seen with liver abscesses – May have internal gas bubbles, which although uncommon, are very specific for splenic abscess – May have multiloculated appearance seen with liver abscesses, but less common with splenic abscess ○ May extend to subcapsular location and may rarely cause splenic rupture with generalized peritonitis • Fungal microabscesses ○ Often multiple, small, hypodense lesions measuring just a few mm ○ Can be very difficult to diagnose on NECT ○ May manifest as multiple punctate splenic calcifications after treatment • Echinococcal (hydatid) cyst ○ Complex cyst with multiple low density "daughter" cysts and thick, enhancing wall composed of fibrous tissue ("cyst within a cyst" appearance) ○ Serpiginous, linear hypodense bands within cyst due to collapsed parasitic membranes (water lily sign) ○ May demonstrate thick peripheral calcification or internal wavy, curvilinear calcification in chronic setting ○ Similar lesions may be seen in liver or peritoneum

Spleen

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Splenic Infarct • Wedge-shaped area of low attenuation at periphery of spleen ○ Very rarely rounded in configuration and in central spleen (potentially mimicking abscess or neoplasm) • No enhancement on contrast-enhanced images

Splenic Tumor • May be single or multiple discrete masses • Most common solid malignancies include lymphoma, melanoma, and other metastases ○ Melanoma and some cystic/necrotic metastases (ovarian cancer, sarcomas, germ cell tumors) can appear low density and cystic, mimicking abscess or fluid collection ○ Lymphoma can present with innumerable tiny hypodense nodules in spleen mimicking microabscesses • Most common benign lesions are lymphangioma and hemangioma ○ Variable appearance; both lesions can appear low density and mimic abscess or fluid collection ○ Hemangioma may appear hypervascular on arterial phase CECT and lymphangioma may show internal loculations and septations

Splenic Trauma • History of recent blunt injury • Linear low density, nonenhancing laceration almost always associated with perisplenic hematoma and hemoperitoneum • ± active arterial extravasation

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Spleen

Splenic Infection and Abscess

Infiltrating Disorders • Sarcoid (and less commonly, Gaucher disease) can commonly present with multiple low-attenuation lesions • Indistinguishable from microabscesses without history • Sarcoid may be associated with similar lesions in liver, hepatosplenomegaly, and thoracic/upper abdominal lymphadenopathy

PATHOLOGY General Features • Etiology ○ Multiple different causes for splenic pyogenic abscesses – Generalized septicemia (most splenic abscesses arise due to hematogenous spread of infection) – Septic emboli (usually in setting of endocarditis with mitral/aortic valve vegetations) – Secondary infection of traumatic splenic hematoma or infarct – Other predisposing risk factors: Recent surgery, other abdominal infections, intravenous drug abuse, immunodeficiency, malignancy or hematologic disorders, trauma, diabetes, and pancreatitis ○ Most fungal microabscesses occur in setting of immunosuppression, HIV/AIDS, or hematologic disorders ○ Echinococcal infections occur due to infection with tapeworm (Echinococcus granulosus) – Most commonly occur in areas with sheep (transmission often via dogs who eat viscera of slaughtered animals) – Most common in South America, Middle East, Eastern Mediterranean, and parts of Africa • Genetics ○ Hemoglobinopathies (sickle cell) predispose to pyogenic abscess

Staging, Grading, & Classification • Pyogenic ○ Unilocular (65%); multilocular or multiple (20%) ○ Gram-negative organisms in 55%: Klebsiella pneumoniae most common pathogen • Fungal ○ Typically microabscesses measuring < 1.5 cm (25%) ○ Most often Candida (most common), Aspergillus, and Cryptococcus ○ Tuberculosis (TB) and Mycobacterium avium-intracellulare (MAI) in AIDS patients • Parasitic ○ Echinococcus granulosus

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pyogenic abscess – Fever (92%), chills, LUQ pain (77%), splenomegaly – May mimic symptoms of pneumonia, ulcer disease, or pancreatitis – Lab data: Leukocytosis (66%), positive blood cultures ○ Echinococcal cyst – Many patients are asymptomatic and may remain without symptoms for years 556

– Symptoms depend on site of infection and size of cyst – Lab data: Eosinophilia in only small minority of patients (< 15%)

Demographics • Age ○ Usually adult patients with predisposing factors (although any age group can be affected) • Gender ○ M=F • Ethnicity ○ No known predilection • Epidemiology ○ Rare: 0.2% of reported autopsies ○ 25% of patients with splenic abscesses are immunocompromised patients

Natural History & Prognosis • Excellent prognosis for pyogenic abscesses in immunocompetent patient • Guarded prognosis in immunocompromised patients with fungal microabscesses • Echinococcal disease can recur many years after treatment and should be monitored periodically for recurrence

Treatment • Splenic pyogenic abscess ○ Traditional treatment is splenectomy with broadspectrum antibiotics – Still standard treatment in setting of multiple pyogenic abscesses or abscess rupture – Mortality postsplenectomy: 6% ○ Spleen-conserving treatment increasingly being utilized – Antibiotics alone may be curative in 75% of small pyogenic abscesses (< 4 cm) – Percutaneous drainage may be utilized for unilocular unruptured abscesses with high reported success rates • Fungal microabscesses ○ Treatment with antifungal medications • Echinococcal cyst ○ Treatment options include surgical resection (especially in setting of ruptured cysts or other complications), percutaneous drainage (± introduction of scolicidal agent), drug therapy (e.g., albendazole), or observation

DIAGNOSTIC CHECKLIST Consider • Differentiate splenic abscesses from mimics, including lymphoma, low-density metastases, or splenic infarcts

Image Interpretation Pearls • Splenic abscesses appear as solitary or multiple lowattenuation cystic lesions in febrile patient

SELECTED REFERENCES 1.

Tonolini M et al: Nontraumatic splenic emergencies: cross-sectional imaging findings and triage. Emerg Radiol. 20(4):323-32, 2013

Splenic Infection and Abscess Spleen

(Left) Color Doppler image shows a well-defined solitary splenic abscess with a hypoechoic necrotic center and a thick irregular wall . The adjacent splenic parenchyma appears normal. Note the typical avascular nature of the abscess. (Right) Axial T1 C+ MR in a patient with LUQ pain and a fever illustrates the characteristic multiseptate appearance of a splenic abscess . Blood cultures identified Staphylococcus and the patient recovered with antibiotics.

(Left) Axial CECT in a 29-yearold intravenous drug abuser with a 3-day history of fever and LUQ pain shows a focal hypodense lesion in the periphery of the spleen's midportion; findings that are consistent with an abscess. (Right) Axial CECT in the same patient reveals lateral perisplenic inflammatory changes , suggesting a possible abscess rupture. An echocardiogram showed multiple vegetations in both the aortic and mitral valves, suggesting that this abscess is due to underlying endocarditis.

(Left) Axial CECT in a 29-yearold known intravenous drug abuser who presented with multiple skin abscesses as well as abdominal pain and fever demonstrates a lowattenuation splenic abscess . (Right) Axial CECT in the same patient demonstrates multiple hepatic abscesses as well. The patient underwent an echocardiogram, which additionally revealed aortic valve vegetations from endocarditis (not shown).

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Spleen

Splenomegaly and Hypersplenism KEY FACTS

TERMINOLOGY • Splenomegaly: Splenic enlargement caused by a number of different underlying disorders

IMAGING • Normal spleen is 13 cm in length • Splenic index (product of length, breadth, and width of spleen): Normally 120-480 cm³ • Splenic weight (splenic index x 0.55): Normally between 100-250 g • Splenomegaly: AP diameter > 2/3 distance of AP diameter of abdominal cavity

PATHOLOGY • Splenomegaly attributable to 5 different general etiologies ○ Congestive – Right heart failure, portal hypertension, sickle cell disease (in acute setting), and splenic vein thrombosis ○ Hematologic

(Left) Frontal radiograph demonstrates "fullness" in the left upper quadrant. The inferior edge of an enlarged spleen is evident. (Right) Coronal T2 MR demonstrates a markedly enlarged spleen in a patient with myelodysplastic syndrome. The most common causes of massive splenomegaly are cirrhosis/portal hypertension, lymphoma, chronic myelogenous leukemia, extramedullary hematopoiesis, myelofibrosis, and Gaucher disease.

(Left) Axial CECT shows a small, cirrhotic liver with widened fissures and signs of portal hypertension, including splenomegaly and varices . In most patients with splenomegaly, there are clues as to the underlying cause on the imaging study, as in this case. (Right) Coronal CECT in an asymptomatic patient demonstrates a mildly enlarged spleen with multiple ill-defined hypodense nodules in a patient with known sarcoidosis. Lymphoma and metastatic disease could have a very similar appearance.

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– Polycythemia vera, myelofibrosis, and hemoglobinopathies ○ Inflammatory/infectious – Mononucleosis and HIV/AIDS most common infections to result in splenomegaly – Sarcoid may result in mild splenomegaly with multiple small hypodensities in liver and spleen ○ Space-occupying lesions – Space-occupying masses in spleen do not commonly cause splenomegaly and are more likely to replace normal splenic tissue ○ Storage and infiltrative disorders – Primary or secondary hemochromatosis, amyloidosis, and glycogen storage diseases

CLINICAL ISSUES • Complications include splenic rupture and hypersplenism ○ Hypersplenism: Hyperfunctioning spleen removes normal RBC, WBC, and platelets from circulation

Splenomegaly and Hypersplenism

Abbreviations • Splenomegaly (SMG) • Hypersplenism (HS)

Definitions • SMG: Splenic enlargement caused by a number of different underlying congestive, hematologic, inflammatory/infectious, neoplastic, or infiltrative disorders • Hypersplenism: Syndrome consisting of splenomegaly and pancytopenia in which bone marrow is either normal or hyperreactive

IMAGING General Features • Best diagnostic clue ○ volume of spleen with convex medial border • Size ○ No consensus on absolute size thresholds for SMG: Different sources suggest different measurements ○ Normal spleen is 13 cm in length – Width and breadth are usually 6 and 8 cm, respectively ○ Splenic index: Normally 120-480 cm³ (product of length, breadth, and width of spleen) ○ Splenic weight: Splenic index x 0.55 – Normal weight: 100-250 g ○ SMG: Anteroposterior (AP) diameter > 2/3 distance of AP diameter of abdominal cavity • Morphology ○ SMG is often associated with abnormal contour of spleen, including rounding of poles and convexity of medial border

Radiographic Findings • Radiography ○ Normal-sized spleen usually not visualized ○ SMG: Splenic tip below 12th rib ○ Marked SMG may displace stomach medially ○ Displacement of splenic flexure of colon (splenic flexure usually anteromedial to spleen)

CT Findings • SMG is usually due to 1 of 5 general etiologies • Congestive ○ Right heart failure: Cardiomegaly with distension of hepatic veins/IVC and passive hepatic congestion ○ Portal hypertension: Splenomegaly with varices, nodular shrunken liver, ascites, and other signs of portal hypertension ○ Splenic or portal vein occlusion or thrombosis (often due to pancreatitis or pancreatic tumors) ○ Sickle cell disease – Acute phase: Diffusely decreased splenic density with splenomegaly – Chronic phase: Development of small autoinfarcted, calcified spleen • Hematologic ○ Polycythemia vera ○ Leukemia

○ Myelofibrosis: SMG due to extramedullary hematopoiesis – May be associated with other signs of extramedullary hematopoiesis (such as paraspinal soft tissue masses) ○ Hemoglobinopathies: May cause splenomegaly (thalassemia) or small, infarcted spleen (sickle cell [SC]) ○ Acute splenic infarction: Global or wedge-shaped hypoenhancement of splenic parenchyma • Inflammatory/infectious ○ Mononucleosis ○ Hepatitis: Splenomegaly due to viremia or cirrhosis with portal hypertension ○ AIDS: SMG may reflect chronic viremia, opportunistic infection, or lymphoma ○ IV drug abuse: SMG due to chronic low-level sepsis ○ Tuberculosis, histoplasmosis: Multifocal low-density granulomas acutely that heal as calcified foci ○ Sarcoidosis: Often associated with innumerable small hypodense splenic granulomas, ± upper abdominal lymphadenopathy, ± hepatomegaly with similar hypodense hepatic granulomas ○ Collagen vascular or autoimmune diseases – Rheumatoid arthritis, scleroderma, etc. – Felty syndrome: Rheumatoid arthritis, splenomegaly, and granulocytopenia ○ Malaria: One of the most common causes of SMG worldwide • Space-occupying lesions ○ Space-occupying masses do not commonly cause SMG and are more likely to replace normal splenic tissue ○ Cysts: Common, but usually do not cause SMG ○ Lymphoma and metastases: Relatively common cause of splenomegaly, especially lymphoma (which may or may not be associated with discrete hypodense lesions in spleen) ○ Primary splenic tumors: Do not typically cause SMG • Storage and infiltrative disorders ○ Secondary hemochromatosis – Increased density of liver and spleen on NECT (iron deposition in RES cells) ○ Primary hemochromatosis – Density of spleen is normal (unlike that of liver) ○ Amyloidosis – NECT and CECT: Generalized or focal density ○ Glycogen storage diseases (e.g., Gaucher disease)

Spleen

TERMINOLOGY

MR Findings • Portal hypertension ○ Gamna-Gandy bodies or siderotic nodules appear as multiple tiny (3-8 mm) foci of T1WI and T2WI signal – Represent hemosiderin deposits related to prior microhemorrhage • Hemochromatosis ○ Involved organs (including spleen) are typically markedly low signal on both T1 and T2WI with signal loss on inphase gradient echo images ○ Primary: Normal signal and size of spleen, with liver and pancreas most typically involved ○ Secondary: Liver, spleen, bone marrow, and lymph nodes most often involved • Sickle cell disease 559

Spleen

Splenomegaly and Hypersplenism ○ Spleen appears low signal on all pulse sequences due to iron deposition • Gaucher disease: May present with focal lesions, which demonstrate either T2WI hypointensity or hyperintensity • Infarction ○ Peripheral, wedge-shaped areas of abnormal signal that vary in signal intensity depending on age of infarct and presence/absence of hemorrhagic transformation – Acute hemorrhagic infarcts may show high T1WI signal – Chronic infarcts tend to be low signal on T1WI and high signal on T2WI • Extramedullary hematopoiesis ○ May present with focal T1WI and T2WI hyperintense, homogeneously enhancing nodules within enlarged spleen

Ultrasonographic Findings • Grayscale ultrasound ○ SMG with normal echogenicity – Infection, congestion (portal hypertension), early sickle cell disease – Hereditary spherocytosis, hemolysis, Felty syndrome – Wilson disease, polycythemia, myelofibrosis, leukemia ○ SMG with hyperechoic splenic parenchyma – Leukemia, post chemotherapy and radiation therapy – Malaria, TB, sarcoidosis, polycythemia – Hereditary spherocytosis, portal vein thrombosis, hematoma, metastases ○ SMG with hypoechoic splenic parenchyma – Lymphoma, multiple myeloma, chronic lymphocytic leukemia – Congestion from portal hypertension, noncaseating granulomatous infection ○ Sickle cell disease: Immediately after sequestration, peripheral hypoechoic areas may be visualized ○ Gaucher disease: Multiple, well-defined, discrete hypoechoic lesions representing fibrosis or infarction

Imaging Recommendations • Best imaging tool ○ CECT with multiplanar reformations

DIFFERENTIAL DIAGNOSIS Other Left Upper Quadrant Masses • e.g., gastric, renal, adrenal tumors

Splenic Trauma • Intrasplenic or subcapsular hematoma may enlarge spleen • Diagnosis usually evident based on imaging and history of trauma

Splenic Infection and Abscess • Pyogenic (bacterial) abscess ○ Low-density cystic mass with thick, irregular enhancing wall ± internal gas and reactive left pleural effusion • Fungal (e.g., Candida, Aspergillus, Cryptococcus) ○ Low-density lesions that may be solitary or multiple and of variable size and may show minimal peripheral enhancement • AIDS: Pneumocystis, mycobacterial (e.g., Mycobacterium avium-intracellulare [MAI]) infection 560

○ Focal low-attenuation splenic lesions ± calcification

PATHOLOGY General Features • Etiology ○ Congestive SMG – CHF, portal hypertension, cirrhosis, cystic fibrosis, splenic vein thrombosis, SC sequestration ○ Neoplasm: Leukemia, lymphoma, metastases, primary neoplasm, Kaposi sarcoma ○ Storage disease: Gaucher, Niemann-Pick, gargoylism, amyloidosis, hemochromatosis, histiocytosis ○ Infection: Hepatitis, malaria, mononucleosis, TB, typhoid, kala-azar, schistosomiasis, brucellosis ○ Hemolytic anemia: Hemoglobinopathy, hereditary spherocytosis, primary neutropenia, thrombocytopenic purpura ○ Extramedullary hematopoiesis: Osteopetrosis, myelofibrosis ○ Collagen disease: SLE, RA, Felty syndrome ○ Most common causes of massive SMG: Lymphoma, chronic myelogenous leukemia, extramedullary hematopoiesis, myelofibrosis, and Gaucher disease

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Many patients asymptomatic, but can result in abdominal pain or palpable mass in left upper quadrant ○ Signs and symptoms often related to underlying cause

Natural History & Prognosis • Complications ○ Splenic rupture, shock, and death • Hypersplenism: Usually develops as result of SMG ○ Hyperfunctioning spleen removes normal RBC, WBC, and platelets from circulation ○ Up to 90% of all platelets may be removed from circulation by spleen in cases of severe SMG

Treatment • Treatment varies based on underlying condition • Splenectomy in symptomatic and complicated cases

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Look for imaging findings that may explain a patient's splenomegaly, such as the presence of cirrhosis/portal hypertension

SELECTED REFERENCES 1.

Manenti A et al: Splenomegaly Secondary to Myeloproliferative Neoplasms and Portal Hypertension. Clin Lymphoma Myeloma Leuk. ePub, 2014

Splenomegaly and Hypersplenism Spleen

(Left) Coronal CECT demonstrates a mildly enlarged spleen with multiple hypodense nodules. The patient was later found to have thoracic lymphadenopathy, and biopsy showed the spleen to be a manifestation of sarcoidosis. (Right) Axial T2 MR demonstrates marked low signal in the liver, spleen, and bone marrow in a patient with hemosiderosis due to multiple blood transfusions.

(Left) Axial CECT shows a markedly enlarged spleen with multiple subtle low-density foci scattered throughout the splenic parenchyma. This was found to be lymphoma, and lymphadenopathy was present elsewhere. (Right) Axial CECT in a patient with non-Hodgkin lymphoma shows splenomegaly and extensive lymphadenopathy . While splenomegaly and lymphadenopathy are characteristic findings in patients with NHL, benign processes, such as sarcoidosis and mononucleosis, may result in similar findings.

(Left) Axial arterial phase CECT in a patient with cirrhosis & portal hypertension shows a swirled moiré pattern of splenic enhancement that disappeared on the portal venous phase. This normal variant is often more prominent in patients with cirrhosis and portal hypertension. (Right) US shows splenomegaly with multiple hypoechoic foci in a patient with granulomatous MAI infection. On US, granulomatous abscesses appear as well-defined, hypoechoic lesions, usually with associated splenomegaly.

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Spleen

Splenic Infarction KEY FACTS

TERMINOLOGY • Global or segmental parenchymal splenic ischemia and necrosis caused by vascular occlusion

IMAGING • Acute findings on CECT ○ Diagnosis best made on portal venous phase images due to heterogeneous arterial phase enhancement ○ Global infarction: Complete nonenhancement of spleen – ± cortical rim sign: Preserved enhancement of peripheral rim of spleen in massive infarction ○ Segmental infarction: Wedge-shaped or rounded lowattenuation area usually at periphery of spleen – Can be multiple, especially when caused by emboli • Chronic findings on CECT ○ Most often results in scarring and volume loss ○ Multiple repetitive infarcts in sickle cell disease can lead to small, calcified spleen (autoinfarcted spleen) ○ Infarct can develop into splenic cyst

(Left) Axial CECT in a sickle cell patient demonstrates an enlarged spleen with multiple wedge-shaped acute splenic infarcts . While sickle cell patients can develop a small, calcified autoinfarcted spleen, the spleen may be enlarged in the early stages of the disease. (Right) Axial CECT demonstrates a large, global infarct of the spleen with only a tiny amount of enhancing splenic tissue . Notice the peripheral enhancement (rim sign) at the margins of the infarct as a result of preserved flow through capsular vessels.

(Left) Axial CECT in a 67-yearold man with a 10-year history of atrial fibrillation, now presenting with acute LUQ pain, demonstrates a peripheral, low-attenuation splenic infarct with straight margins . (Right) Axial CECT in the same patient identifies a left ventricular thrombus as the source of the arterial embolus to the spleen. Embolic disease is likely the most common cause of splenic infarcts in older patients.

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• Complications (< 20% of patients) ○ Perisplenic fluid/hematoma suggests splenic rupture ○ Development of rim-enhancing fluid collection: Splenic abscess

TOP DIFFERENTIAL DIAGNOSES • • • •

Splenic laceration Splenic cyst or abscess Heterogeneous arterial phase enhancement of spleen Splenic tumors

CLINICAL ISSUES • Many different causes, but 2 most common are ○ Hematologic disease or hematologic malignancies (sickle cell, myelofibrosis, leukemia, etc.) ○ Embolic conditions (septic emboli, cardiac emboli from atrial fibrillation, etc.) • Most cases require no treatment, but rarely surgery or intervention for pain or complications

Splenic Infarction

Definitions • Global or segmental parenchymal splenic ischemia and necrosis caused by vascular occlusion

IMAGING

□ Sites of old infarcts may show calcification □ Remaining spleen may undergo compensatory hypertrophy – Multiple repetitive infarcts in sickle cell disease can lead to a small, calcified spleen (autoinfarcted spleen) – Infarct can develop into splenic cyst (secondary or acquired cyst)

General Features

MR Findings

• Best diagnostic clue ○ Peripheral, wedge-shaped, nonenhancing areas within splenic parenchyma on CECT in patients with LUQ pain • Location ○ Entire spleen may be infarcted or more commonly segmental areas • Morphology ○ Most commonly wedge-shaped areas of nonenhancement when infarct is segmental – Straight margins indicate vascular etiology (rather than a mass or fluid collection) – May very rarely be rounded (atypical appearance)

• T1WI ○ Low signal within area of infarct (can show high T1WI signal due to hemorrhagic infarct) • T2WI ○ Heterogeneous high signal within area of infarct • T1WI C+ ○ Wedge-shaped area of hypoenhancement

Radiographic Findings • Radiography ○ May be associated with lower left lobe atelectasis and pleural effusion on chest x-ray

CT Findings • NECT ○ Infarcts may be difficult (or impossible) to visualize without intravenous contrast ○ Areas of hemorrhagic transformation within infarcts appear hyperdense on NECT • CECT ○ Acute findings – Diagnosis best made on portal venous phase images: Heterogeneous enhancement during arterial phase (due to differential enhancement of red and white pulp) makes identification of subtle infarcts difficult – Global: Complete nonenhancement of spleen □ ± cortical rim sign: Preserved enhancement of peripheral rim of spleen in massive infarction due to preserved flow from capsular vessels □ Mottled higher density areas within infarcted spleen may represent either tiny islands of residual enhancing splenic tissue or hemorrhage – Segmental: Wedge-shaped or rounded lowattenuation area usually at periphery of spleen □ Can be multiple, especially when caused by emboli □ In some instances, accessory spleens (splenules) may be infarcted □ Spleen may or may not be enlarged in acute phase – Complications (< 20% of patients) □ Presence of fluid or hematoma surrounding spleen in setting of infarct suggests splenic rupture (most often in setting of large or global infarct) □ Development of discrete rim-enhancing fluid collection ± internal gas should raise concern for splenic abscess ○ Chronic findings – Infarcts should evolve over time, leaving areas of scarring and volume loss in spleen

Spleen

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Wedge-shaped hypoechoic area(s) within periphery of spleen – May rarely be rounded or irregularly shaped at center of spleen (atypical) ○ Bright band sign: Highly echogenic linear bands in area of infarct may be specific sign of infarction • Color Doppler ○ Diminished or absent flow in areas of infarction

Angiographic Findings • Conventional angiography: Main splenic artery occlusion or segmental emboli

Imaging Recommendations • Best imaging tool ○ Portal venous phase CECT

DIFFERENTIAL DIAGNOSIS Splenic Laceration • Hypodense, wedge-shaped defect in spleen in patient with recent history of trauma • Almost always high-attenuation hematoma adjacent to laceration ± large hemoperitoneum • May have high-attenuation active arterial extravasation

Splenic Cyst • Nonneoplastic cysts divided into primary "true" epithelial cysts and secondary "false" cysts (no epithelial lining) ○ Primary cysts most often epidermoid cysts (10-25% of all splenic cysts), but can be parasitic (echinococcal) ○ Secondary cysts result from prior infection, infarction, trauma, or hematoma • Usually well-defined, rounded fluid attenuation cyst with variable internal complexity and peripheral calcification • Can result from prior infarct, but much better defined, rounded, and water density

Splenic Abscess • Complex intraparenchymal or perisplenic loculated fluid collection with peripheral enhancement, internal complexity/debris, and possible internal gas • Unlike infarct, splenic abscess is a discrete, rounded fluid collection with adjacent fat stranding/inflammation 563

Spleen

Splenic Infarction ○ May develop from evolution of prior infarct • May appear as multiple small lesions (microabscesses) due to fungal infections in immunocompromised patients

Normal Heterogeneous Enhancement of Spleen in Arterial Phase • Striated appearance of spleen in arterial phase (due to differential enhancement of red and white pulp) should not be confused with splenic infarcts

Splenic Tumors • Primary or secondary neoplasms of spleen (whether benign or malignant) should appear focal and mass-like, with rounded borders (not wedge-shaped or linear) • Lymphoma and some metastases (metastatic melanoma or mucinous neoplasms) may appear low density and hypoenhancing, resembling density of infarcts

PATHOLOGY General Features • Etiology ○ Large variety of different causes resulting in occlusion of arterial/venous vasculature supplying spleen – Hematologic disorders □ Sickle cell hemoglobinopathies: Risk of splenic infarct during high-altitude travel or airplane flight □ Myelofibrosis □ Hypercoagulable states □ Leukemia and lymphoma □ Any cause of hypersplenism/splenomegaly (including mononucleosis and infections) – Thromboembolism □ Atrial fibrillation □ Aortic atherosclerotic disease with embolization to splenic artery □ Aortic valve emboli from subacute bacterial endocarditis – Anatomic causes □ Splenic torsion (including torsion due to wandering spleen): Laxity or absence of splenic ligaments results in spleen "wandering" to ectopic locations, increasing incidence of torsion and infarction – Miscellaneous □ Pancreatitis or pseudocysts □ Portal hypertension □ Any surgical procedure involving upper abdominal organs (particularly pancreatic tail, stomach, left adrenal gland) □ Collagen vascular disease □ Tumors (gastric, pancreatic, adrenal) involving splenic hilum and vessels

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Many patients can be asymptomatic (1/3 of patients) – Most common with small splenic infarcts ○ Most common symptoms: LUQ pain, fever, chills, malaise, nausea, vomiting

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○ May be associated with other infarcts (e.g., kidney and bowel) in patients with splenic infarcts due to emboli • Lab data: Anemia (53%), leukocytosis (41%), elevated platelet count (7%)

Demographics • Age ○ 2-87 years (mean: 54) • Gender ○ M=F • Epidemiology ○ Many different causes, but 2 most common causes are – Hematologic disease or hematologic malignancies: Sickle cell, myelofibrosis, leukemia, etc; most common causes in younger patients □ Probably caused by congestion and occlusion of splenic vessels by abnormal cells associated with hematologic disorder □ Most common cause of splenic infarcts overall – Embolic conditions (septic emboli, cardiac emboli from atrial fibrillation, embolization of ulcerated atherosclerotic plaque); most common cause in older patients

Natural History & Prognosis • Most cases require no treatment and symptoms cease naturally • Rarely surgery or intervention for pain or complications ○ Complications: Abscess, rupture, subcapsular hematoma, hemorrhage, pseudocyst formation

Treatment • Asymptomatic: Supportive treatment (pain control with analgesics) • Symptomatic: Splenectomy for intolerable/increasing pain or splenic rupture; image-guided drainage for splenic abscess formation

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Wedge-shaped, peripheral area of nonenhancement on portal venous phase CECT • Do not confuse normal striated enhancement pattern on arterial phase CECT for splenic infarct

SELECTED REFERENCES 1.

2. 3.

Gaetke-Udager K et al: Multimodality imaging of splenic lesions and the role of non-vascular, image-guided intervention. Abdom Imaging. 39(3):570-87, 2014 Llewellyn ME et al: The sonographic "bright band sign" of splenic infarction. J Ultrasound Med. 33(6):929-38, 2014 Lawrence YR et al: Splenic infarction: an update on William Osler's observations. Isr Med Assoc J. 12(6):362-5, 2010

Splenic Infarction Spleen

(Left) Axial CECT in a young child with acute abdominal pain demonstrates a large, hypoenhancing mass in the pelvis. (Right) Coronal CECT in the same patient again shows the same mass in the pelvis with fluid in the adjacent right pelvis and no spleen noted in the abdomen. This mass was found at surgery to represent torsion and infarction of a "wandering" spleen. The spleen in such cases is found in ectopic locations due to laxity or absence of the splenic ligaments.

(Left) A large fluid collection envelops small areas of normal splenic tissue . This was found at surgery to represent a massively infarcted spleen with contained rupture, resulting in the fluid collection. (Right) Patient status post embolization for hypersplenism shows severe splenomegaly with no enhancement except for a small portion of the medial spleen . Massive acute infarction is often not desired in splenic embolotherapy, as patients can develop infections of infarcted tissue.

(Left) Sagittal ultrasound in a 48-year-old woman with myelodysplastic syndrome and a 1-week history of LUQ pain shows marked splenomegaly & a wedge-shaped hypoechoic area in the lower pole of the spleen, consistent with infarction. The patient was placed on analgesics and recovered uneventfully. (Right) Axial NECT in a 55year-old woman presenting with a history of sickle cell anemia demonstrates a spleen that is very small, densely calcified , and nonfunctional, sometimes termed "autosplenectomy."

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Spleen

Splenic Trauma KEY FACTS

TERMINOLOGY • Splenic parenchymal injury ± capsule disruption

IMAGING • High-attenuation hemoperitoneum > 30 HU or perisplenic clot > 45 HU ○ Perisplenic hematoma: Located adjacent to spleen and implies disruption or rupture of splenic capsule ○ Intraparenchymal hematoma: Typically round or irregular in shape ○ Subcapsular hematoma: Constrained by splenic capsule and crescentic in shape • Sentinel clot sign: Highest density blood localizes adjacent to spleen (or any site of injury) ○ Indicates splenic injury even without demonstrable laceration • Parenchymal laceration: Irregular linear, branching, or stellate area of nonenhancing low attenuation

(Left) Axial CECT in an 87year-old woman who fell at a nursing home demonstrates a splenic parenchymal laceration and intraperitoneal blood , as well as a lentiform heterogeneous and higher attenuation collection flattening the normal convex lateral splenic contour, representing a subcapsular hematoma . (Right) Axial CECT in a 23-year-old man injured in a motor vehicle accident shows a shattered spleen with a sentinel clot in the perisplenic region and large hemoperitoneum .

(Left) Axial CECT in a 19-yearold man who was an unrestrained passenger in a motor vehicle accident shows marked upper abdominal hemoperitoneum , a shattered spleen with intrasplenic high-attenuation pseudoaneurysms , and a focus of active arterial extravasation lateral to the spleen within the peritoneal cavity . (Right) Axial CECT in the same patient shows the active arterial extravasation extending into the left paracolic gutter with surrounding hemoperitoneum .

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• Splenic fracture: Deep laceration extending from outer capsule through splenic hilum • Splenic infarction: Unusual (< 2% of cases) in the setting of trauma, and can be segmental or complete • Active arterial extravasation: High-attenuation focus isodense with aorta, surrounded by lower attenuation clot or hematoma ○ Distinction between active extravasation and pseudoaneurysm using delayed phase images

CLINICAL ISSUES • Most commonly injured solid abdominal organ in blunt trauma and most common abdominal organ injury requiring surgery • Prone to develop delayed hemorrhage, but excellent prognosis with early intervention (surgery/embolization) • Identification of active arterial extravasation or pseudoaneurysm best predictor of need for surgery and failure of nonoperative management

Splenic Trauma

Synonyms • Splenic laceration or splenic fracture

Definitions • Splenic parenchymal injury ± capsule disruption

IMAGING General Features • Best diagnostic clue ○ Low-attenuation splenic laceration with high-density active bleeding

○ Active arterial extravasation: High-attenuation focus isodense with aorta, surrounded by lower attenuation clot or hematoma – May be linear (spurting vessel) or rounded (pseudoaneurysm): Distinction is made using delayed phase images □ Active extravasation (unlike pseudoaneurysm) changes in size and morphology between initial and delayed phases □ Although delayed images are not routinely included in most trauma protocols, addition of delayed images can be helpful if there is site of suspicion noted on initially acquired portal venous phase images

Radiographic Findings

Ultrasonographic Findings

• Radiography ○ Abdominal radiography – Left upper quadrant soft tissue mass – Signs of intraperitoneal fluid with widening of distance between flank strip and descending colon – Fluid in pelvis with prominent pelvic "dog ears" ○ Chest radiography demonstrates associated injuries – Lower left lobe atelectasis &/or consolidation – Left rib fractures, pneumothorax, pleural effusion

• Subtle laceration may be missed, as ultrasound is insensitive for parenchymal injury ○ Lacerations can be hypoechoic or isoechoic to splenic parenchyma and can be very difficult to detect with US • Free intraperitoneal fluid with low-level echoes representing hemoperitoneum and echogenic perisplenic clot

CT Findings • NECT ○ High-attenuation hemoperitoneum > 30 HU or perisplenic clot > 45 HU – Perisplenic, intraparenchymal, or subcapsular hematoma □ Perisplenic hematoma: Located adjacent to spleen and implies disruption or rupture of splenic capsule □ Intraparenchymal hematoma: Typically round, ovoid, or irregular in shape □ Subcapsular hematoma: Constrained by splenic capsule; crescentic in shape and compresses lateral margin of parenchyma ○ Sentinel clot sign: Highest density blood localizes adjacent to spleen (or any site of injury) – Indicates splenic injury even in absence of demonstrable laceration ○ Layered or lamellated clot if bleeding is intermittent • CECT ○ Parenchymal laceration: Irregular linear, branching, or stellate area of nonenhancing low attenuation within parenchyma – May extend to splenic capsule resulting in capsular tear – Should become less conspicuous on follow-up imaging ○ Splenic fracture: Deep laceration extending from outer capsule through splenic hilum ○ Splenic infarction: Unusual (< 2% of cases) in setting of trauma – Can be segmental or complete – Wedge-shaped area of hypoattenuation – Due to arterial thrombosis after intimal injury – Risk of delayed rupture or abscess formation

Spleen

TERMINOLOGY

Angiographic Findings • Avascular parenchymal laceration with amorphous parenchymal extravasation • Flattened lateral contour of spleen due to subcapsular hematoma • Rounded contrast collections (pseudoaneurysms)

Imaging Recommendations • Best imaging tool ○ CECT • Protocol advice ○ Arterial phase images more sensitive for active extravasation or pseudoaneurysm ○ Portal venous phase images more sensitive for parenchymal injury (i.e., laceration) ○ Delayed images to differentiate active arterial extravasation from pseudoaneurysm

DIFFERENTIAL DIAGNOSIS Splenic Cleft • Normal anatomic variant that appears as a thin, fissure-like band of low attenuation • Most often occurs at upper or lower pole of spleen • No evidence of adjacent hematoma, free fluid, or stranding

Splenic Abscess • Rounded, irregular, low-attenuation collection within splenic parenchyma • Clinical signs of infection: Fever, increased white blood cell count, left pleural effusion • No history of trauma or hemoperitoneum

Splenic Infarct • Wedge-shaped area of low attenuation usually located at periphery of spleen • Associated with splenomegaly, systemic emboli (such as from endocarditis), and multiple other causes

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Spleen

Splenic Trauma ○ Blunt abdominal trauma, LUQ pain, hypotension – Often associated with left chest pain due to rib fractures, left lower lobe lung consolidation, or left hemothorax – Injury to other abdominal organs in 36.5% – 80% with splenic injury have extra-abdominal injuries

• Typically no surrounding free fluid or hematoma (in the absence of rupture) • Infarct may evolve into abscess

Splenic Cyst • Rounded, nonenhancing cystic lesion with definable cyst wall ± peripheral calcification

PATHOLOGY General Features • Etiology ○ Most commonly due to blunt trauma with blow to left upper quadrant (LUQ) – Motor vehicle collisions most common cause ○ Penetrating trauma to spleen less common ○ Rarely iatrogenic trauma to spleen during surgery (particularly colon surgery) ○ Increased risk of splenic injury in patients with splenomegaly (from any cause) • Associated abnormalities ○ Injuries to left thorax, tail of pancreas, left liver lobe, &/or mesentery

Staging, Grading, & Classification • Grading may be misleading: "Minor" injuries may go on to devastating delayed bleed or delayed rupture • AAST (American Association for Surgery of Trauma) grading system is based on extent of injury at laparotomy and applied to CT findings ○ Does not take into account active extravasation and pseudoaneurysm formation ○ I: Subcapsular hematoma (< 10% of surface area of spleen) or laceration < 1 cm ○ II: Subcapsular hematoma (10-50% of surface area of spleen) or laceration 1-3 cm ○ III: Subcapsular hematoma (> 50% of surface area of spleen), parenchymal hematoma > 5 cm or expanding laceration > 3 cm or involving trabecular vessels, ruptured subcapsular or parenchymal hematoma ○ IV: Laceration involving segmental or hilar vessels with devascularization/infarct of at least 25% of spleen ○ V: Shattered spleen; hilar vascular injury with complete devascularization/infarct of spleen • Marmery MDCT-based grading system ○ I: Subcapsular hematoma (< 1 cm thick), laceration (< 1 cm in depth), or parenchymal hematoma (< 1 cm in diameter) ○ II: Subcapsular hematoma (1-3 cm thick), laceration (1-3 cm in depth), or parenchymal hematoma (1-3 cm in diameter) ○ III: Subcapsular hematoma (> 3 cm thick), laceration (> 3 cm in depth), or parenchymal hematoma (> 3 cm in diameter); splenic capsular rupture ○ IVA: Active extravasation in intraparenchymal or subcapsular hematoma; pseudoaneurysm or arteriovenous fistula; shattered spleen ○ IVB: Active intraperitoneal bleeding

CLINICAL ISSUES Presentation • Most common signs/symptoms 568

Demographics • Epidemiology ○ Most commonly injured solid abdominal organ in blunt trauma ○ Most common abdominal organ injury requiring surgery

Natural History & Prognosis • Prone to develop delayed hemorrhage, but excellent prognosis with early intervention (surgery/embolization) • Identification of active arterial extravasation or pseudoaneurysm best predictor of need for surgery and failure of nonoperative management

Treatment • Hemodynamically unstable patients with splenic injury undergo surgery if focused assessment with sonography for trauma (FAST) scan or diagnostic peritoneal lavage (DPL) are positive. ○ 29% of all patients and 40% of children may not have hemoperitoneum and DPL/FAST may be falsely negative • Hemodynamically stable patients with AAST grade I-III splenic injury and without other injuries often conservatively (observation or embolization) managed ○ Conservative management in up to 70% of cases ○ Avoids risks of surgery and post-splenectomy sepsis ○ Active extravasation, pseudoaneurysm, or hemoperitoneum in hemodynamically stable patients managed with embolization ○ Embolization generally not utilized for higher grade (> III) injuries and older patients splenectomy ○ Splenectomy in higher grade injuries, hemodynamic instability, or failed conservative management (delayed splenic rupture) • Nonoperative management generally preferred in pediatric patients

DIAGNOSTIC CHECKLIST Consider • Consider congenital splenic cleft (rather than laceration) in absence of perisplenic hematoma or free fluid • Innocuous splenic injuries may lead to life-threatening delayed hemorrhage, especially with anticoagulation

SELECTED REFERENCES 1.

2.

3.

Uyeda JW et al: Active hemorrhage and vascular injuries in splenic trauma: utility of the arterial phase in multidetector CT. Radiology. 270(1):99-106, 2014 Boscak AR et al: Optimizing trauma multidetector CT protocol for blunt splenic injury: need for arterial and portal venous phase scans. Radiology. 268(1):79-88, 2013 Post R et al: Computed tomography blush and splenic injury: does it always require angioembolization? Am Surg. 79(10):1089-92, 2013

Splenic Trauma Spleen

(Left) Axial CECT in a 39-yearold woman who sustained multiple injuries in a motor vehicle accident shows the irregular and linear areas of decreased enhancement within the spleen. (Right) Axial CECT in the same patient again illustrates the areas of decreased enhancement within the spleen , as well as a small perisplenic hematoma in this typical case of splenic laceration.

(Left) Axial CECT shows a splenic fracture with active extravasation. Note the fracture of the lower pole featuring a site of highattenuation arterial extravasation . (Right) Axial CECT in the same patient demonstrates a large perisplenic hematoma and extensive arterial extravasation .

(Left) Axial CECT in a young man injured in a motor vehicle accident shows a splenic parenchymal laceration with a high density clot adjacent to the spleen. (Right) Axial CECT in the same patient again illustrates the clot adjacent to the spleen , as well as lower density and more homogeneous blood elsewhere within the peritoneal cavity . This is characteristic of the sentinel clot sign. The injury healed without surgical intervention.

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Spleen

Splenosis KEY FACTS

TERMINOLOGY • Dissemination of splenic tissue into ectopic locations following splenic rupture (either traumatic or iatrogenic)

IMAGING • Can occur in virtually every compartment of body ○ Most common in abdomen/pelvis (65% of cases) ○ Usually located within peritoneal cavity (greater omentum, bowel serosa, parietal peritoneum, undersurface of diaphragm) ○ Less common locations include thorax (usually after diaphragmatic rupture) and subcutaneous soft tissues • MDCT: Multiple nodules or masses scattered throughout abdomen or pelvis (usually peritoneal cavity) ○ Should follow appearance of spleen on all phases of enhancement ○ Slightly hypoattenuating (5-10 HU less) compared to liver on NECT, striated enhancement on arterial phase, and homogeneous enhancement on venous/delayed phases

(Left) Axial CECT demonstrates absence of the spleen (patient had a history of prior splenectomy for trauma) with small enhancing nodules in the left upper quadrant. Splenosis is not infrequently seen in close proximity to the splenectomy bed. (Right) Axial CECT in the same patient shows additional splenic implants along the serosal surface of the left colon and along the posterior margin of the right liver lobe. Splenosis is most commonly seen within the peritoneal cavity, with extraperitoneal splenosis more rare.

(Left) Axial CECT in a patient with remote history of abdominal trauma shows multiple soft tissue nodules along the peritoneal surfaces, which might be mistaken for carcinomatosis, but represent splenosis. (Right) Axial CECT shows an enhancing soft tissue nodule in the left cardiophrenic angle. The patient had a distant history of traumatic splenic injury with diaphragmatic rupture, the most common reason for thoracic splenosis. Thoracic splenosis is quite rare compared to abdominal/pelvic splenosis.

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• MR: Follows appearance and enhancement of normal spleen on all sequences • Tc-99m heat-denatured RBC scan: sensitivity/specificity ○ uptake within nodules

TOP DIFFERENTIAL DIAGNOSES • • • • •

Peritoneal carcinomatosis Accessory spleen Polysplenia Visceral mass or malignancy Peritoneal endometriosis

CLINICAL ISSUES • Can mimic peritoneal carcinomatosis or primary malignancies on CT and PET • No other clinical significance in most cases • Most patients are asymptomatic, but rarely, symptoms are due to hemorrhage, rupture, torsion, infarction, or bowel obstruction

Splenosis

Definitions • Dissemination of splenic tissue into ectopic locations following splenic rupture (either traumatic or iatrogenic)

IMAGING

Visceral Mass or Malignancy • Splenosis can mimic pancreatic, adrenal, renal, and gastric masses (and vice versa) ○ Splenosis abutting pancreatic tail can mimic neuroendocrine tumor • CT/MR enhancement characteristics and nuclear scintigraphy helpful in differentiation

General Features

Peritoneal Endometriosis

• Location ○ Most common in abdomen/pelvis (65% of cases) – Usually located within peritoneal cavity (greater omentum, bowel serosa, parietal peritoneum, undersurface of diaphragm) – Involvement of extraperitoneal spaces uncommon ○ Can occur in virtually every compartment of body – Less common locations include thorax (usually after diaphragmatic rupture), subcutaneous soft tissues, and even intracranial cavity

• Soft tissue nodules with variable enhancement usually located in pelvis (uterine ligaments, cul-de-sac, fallopian tubes, etc.)

CT Findings • Multiple nodules scattered throughout abdomen or pelvis • Nodules follow appearance of spleen on all phases ○ Slightly hypoattenuating (5-10 HU less) compared to liver on NECT, striated enhancement on arterial phase, and homogeneous enhancement on venous/delayed phases

MR Findings • Follows signal/enhancement of spleen on all sequences • T1WI: Hypointense to liver; slightly hyperintense to muscle • T2WI: Hyperintense to liver

Ultrasonographic Findings • Nonspecific round/oval, homogeneous mass(es)

Nuclear Medicine Findings • PET ○ Splenosis nodules can be FDG avid and mimic neoplasm • Tc-99m sulfur colloid ○ uptake within splenic nodules (similar to native spleen) • Tc-99m labeled heat-denatured RBC scintigraphy ○ sensitivity/specificity with uptake within nodules

Imaging Recommendations • Best imaging tool ○ Tc-99m labeled heat-denatured RBC scan

PATHOLOGY General Features • Etiology ○ Blunt traumatic disruption of splenic capsule with seeding of tissue into peritoneal cavity – Hematogenous spread may also play a role ○ Does not occur after elective splenectomy (no rupture of capsule)

Gross Pathologic & Surgical Features • Reddish-blue color; no capsule • Supplied by small perforating vessels from local tissues ○ Not supplied by splenic artery branches, unlike splenule

Microscopic Features • May completely resemble normal splenic tissue ○ Cannot differentiate from splenule based on histology

CLINICAL ISSUES Presentation • Most are asymptomatic • Rarely symptomatic due to hemorrhage, rupture, torsion, infarction, or bowel obstruction

Demographics • Epidemiology ○ Most cases reported in adults; M > F ( trauma in men) ○ ~ 70% of patients with splenectomy following trauma ○ Usually detected years after trauma

Natural History & Prognosis

• Usually associated with ascites, omental/peritoneal stranding and nodularity, and known history of underlying malignancy

• No clinical significance in most cases • Recurrent disease after splenectomy with hematologic disorders (idiopathic thrombocytic purpura, lymphoma, etc.) • No Howell-Jolly bodies, Heinz bodies, or abnormal RBCs on peripheral blood smear despite splenectomy ○ Indicates patient has functioning spleen

Accessory Spleen

Treatment

• Congenital ectopic splenic tissue due to failure in fusion of splenic foci during development • Most cases are small, solitary, and adjacent to splenic hilum • May hypertrophy after splenectomy and mimic splenosis

• In most cases, no treatment is necessary • Surgical resection only if complications or symptoms are present

DIFFERENTIAL DIAGNOSIS Peritoneal Carcinomatosis

Polysplenia • Multiple small spleens associated with abdominal situs inversus and cardiovascular anomalies

Spleen

TERMINOLOGY

SELECTED REFERENCES 1.

Diop AD et al: CT imaging of peritoneal carcinomatosis and its mimics. Diagn Interv Imaging. ePub, 2014

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Spleen

Splenic Cyst KEY FACTS

IMAGING • Spectrum of appearances on CT ○ Solitary, well-defined, water density, unilocular cystic lesion – Thin wall with sharp interface to normal splenic tissue – No peripheral/intracystic enhancement or solid component ○ Some cysts can have septations, trabeculations, thick wall, internal necrotic debris, or calcification – May have attenuation greater than simple fluid (due to hemorrhage or protein) – Thin eggshell calcification or thick, irregular peripheral calcification ○ Congenital and acquired cysts may be indistinguishable – Congenital cysts more likely simple in appearance – Acquired cysts often complex with calcification

TOP DIFFERENTIAL DIAGNOSES • Splenic infection and abscess

(Left) Axial CECT shows a water density mass with a calcified wall within the spleen. Note the absence of any enhancing or soft tissue components within this splenic cyst. (Right) Postsplenectomy specimen in the same patient shows the calcified, fibrous wall of the cyst. This was an acquired cyst, probably as a result of prior trauma or infarction.

(Left) Coronal CECT in a young woman demonstrates a large, simple-appearing splenic cyst . The patient was symptomatic with pain and early satiety and consequently underwent surgical cyst deroofing. (Right) Axial CECT demonstrates a large, nonenhancing, multiseptated splenic cyst replacing most of the spleen. Only a posterior sliver of normal spleen remains .

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• Splenic metastases and lymphoma • Benign primary splenic tumors • Intrasplenic pseudocyst

PATHOLOGY • Congenital epidermoid ("true" cyst) ○ May be due to intrasplenic sequestration of peritoneal mesothelial cells during embryologic development • Acquired cysts (secondary/"false" cysts or pseudocysts) ○ Due to prior trauma, hematoma, infarction, or infection ○ Arise due to liquefactive necrosis and cystic change

CLINICAL ISSUES • Most cysts discovered incidentally on imaging • Small and asymptomatic: No treatment • Symptomatic cysts usually treated, with options including percutaneous aspiration/drainage, cyst decapsulation or unroofing, and partial/complete splenectomy ○ Splenectomy for symptomatic large cysts (> 5 cm)

Splenic Cyst

General Features • Best diagnostic clue ○ Sharply defined, spherical cystic lesion of water density • Key concepts ○ Classification – Congenital epidermoid cysts (primary or "true" cyst) □ Demonstrate inner cellular endothelial lining □ Account for 10-25% of all splenic cysts – Acquired cysts (secondary or "false" cysts) □ No inner cellular lining, but have fibrous wall □ Account for 80% of splenic cysts □ Due to prior trauma, hematoma, or infarction

Splenic Metastases and Lymphoma • Metastases ○ Homogeneous hypovascular tumors, mucinous neoplasms, and necrotic tumors may mimic cysts ○ Melanoma can appear low density due to necrosis (mimicking cyst) • Lymphoma ○ Homogeneously enlarged spleen, multiple tiny hypodense nodules, or discrete hypodense mass(es) ○ Discrete masses are hypodense and homogeneous

Radiographic Findings

Benign Primary Splenic Tumors

• Curvilinear wall calcification in left upper quadrant

• Most commonly hemangioma and lymphangioma • May appear solid or cystic, and can appear completely simple and indistinguishable from splenic cyst • Hemangiomas may be hypervascular on arterial phase CECT • Lymphangiomas may be multiloculated with septations

CT Findings • Spectrum of appearances ○ Solitary, well-defined, water density unilocular cyst – Thin wall with sharp interface to normal splenic tissue – No peripheral or intracystic enhancement; no solid, nodular soft tissue component – Always intraparenchymal (no exophytic component) ○ Some cysts can have septations, trabeculations, thick wall, and internal necrotic debris – May have attenuation greater than simple fluid (due to hemorrhage or protein) ○ Cysts may have thin eggshell calcification or thick, irregular peripheral calcification • Congenital and acquired cysts may be indistinguishable ○ Congenital cysts more likely to be simple in appearance ○ Acquired cysts more likely complex with calcification

MR Findings • Most cysts are T2 hyperintense and T1 hypointense • May have signal intensity on T1WI due to blood products or protein within cyst (especially if attenuation on CT)

Ultrasonographic Findings • Anechoic with smooth margins and thin walls • May have internal echoes, septations, and debris • Peripheral echogenic calcifications ± acoustic shadowing

DIFFERENTIAL DIAGNOSIS

Spleen

○ Chronic cysts often demonstrate peripheral or serpiginous, wavy internal calcification ○ May be associated with similar cystic lesions in liver and peritoneal cavity

IMAGING

Intrasplenic Pseudocyst • Pseudocyst developing in pancreatic tail after pancreatitis may invaginate into splenic parenchyma

PATHOLOGY General Features • Etiology ○ Congenital epidermoid ("true" cyst) – Etiology unclear, but may be due to sequestration of peritoneal mesothelial cells within spleen during embryologic development ○ Acquired cysts (secondary/"false" cysts or pseudocysts) – Most often due to prior trauma, hematoma, infarction, or infection (including mononucleosis) – Due to liquefactive necrosis and cystic change

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most cysts discovered incidentally on imaging performed for other reasons ○ Rarely present with pain or palpable mass

Splenic Infection and Abscess

Natural History & Prognosis

• Pyogenic abscess ○ Solitary or multiple, with well-defined irregular borders, peripheral enhancement, and central fluid density ○ ± internal gas due to gas-forming organism ○ Usually clinical history of fever, WBC, and pain • Fungal abscess ○ Usually microabscesses with tiny, hypodense nodules throughout spleen • Parasitic echinococcal or hydatid cyst ○ Complex cyst with internal low-density "daughter" cysts and thick wall composed of fibrous tissue ○ Often serpiginous, linear densities within cyst due to collapsed parasitic membranes

• Complications are rare and include intracystic hemorrhage, rupture, or superinfection

Treatment • Small and asymptomatic no treatment • Symptomatic cysts usually treated, with options including percutaneous aspiration/drainage, cyst decapsulation or unroofing, and partial/complete splenectomy ○ Splenectomy for symptomatic large cysts (> 5 cm)

SELECTED REFERENCES 1.

Rana AP et al: Splenic epidermoid cyst - a rare entity. J Clin Diagn Res. 8(2):175-6, 2014

573

Spleen

Primary Splenic Tumors KEY FACTS

IMAGING • Benign tumors ○ Hemangioma: Most common benign splenic tumor – Classic peripheral nodular enhancement seen in hepatic hemangiomas often not present – Like liver hemangiomas, may demonstrate marked hyperintensity on T2 MR and variables degrees of arterial hyperenhancement with persistent delayed enhancement – May be multiple as part of generalized angiomatosis (Klippel-Trenaunay-Weber syndrome) ○ Lymphangioma: Thin-walled, low-density or cystic lesion (can be solitary or multiple) with sharply defined margins ○ Hamartoma: Rare benign tumor of spleen with nonspecific imaging appearance – Heterogeneous early enhancement which may persist and become more homogeneous on delayed images • Malignant tumors

(Left) Axial CECT in the arterial phase demonstrates an incidentally noted splenic mass with a hypervascular rim of peripheral enhancement. (Right) Axial CECT in the same patient in the venous phase demonstrates that the mass now shows homogenous enhancement with central fillin. While the typical nodular, centripetal enhancement seen with hepatic hemangiomas is less common in the spleen, splenic hemangiomas often demonstrate avid enhancement.

(Left) Axial CECT in a patient with Klippel-Trenaunay-Weber syndrome demonstrates innumerable hypodense lesions in the spleen, compatible with multiple hemangiomas, a classic finding in this disorder. (Right) Ultrasound demonstrates an incidentally identified echogenic mass arising from the spleen, classic for a splenic hemangioma. Note the central hypoechoic scar, a common feature of larger hemangiomas.

574

○ Primary lymphoma: Most often non-Hodgkin lymphoma (B-cell origin), but much less common than secondary lymphomatous involvement of spleen – Imaging patterns including enlarged spleen without discrete mass, solitary dominant hypodense mass, or multifocal hypodense lesions ○ Angiosarcoma: Rare, highly aggressive malignant tumor of spleen, with propensity for early, widespread metastases (patients usually die within 1 year) – Often multiple lesions with variable enhancement that may superficially resemble hemangiomas

CLINICAL ISSUES • Most benign splenic tumors are incidental findings on imaging studies performed for other reasons • Splenic malignancies may present with LUQ pain, palpable mass, splenomegaly, fever, or weight loss • Suspicious tumors (based on either imaging or clinical scenario) should lead to biopsy ± splenectomy

Primary Splenic Tumors

Definitions • Benign or malignant tumors originating in spleen

IMAGING

□ Usually affects older individuals (mean age: 50-59 and M = F) – Extremely poor prognosis with early, widespread metastases (patients usually die within 1 year) – Metastases most commonly affect liver (70%), lung, pleura, nodes, bone, and brain (30%)

Key Concepts

CT Findings

• Benign tumors ○ Hemangioma – Most common primary benign neoplasm of spleen, with autopsy incidence: 0.03-14% – Primarily affects adults with peak age 35-55 years – Large hemangiomas may cause splenomegaly and spontaneous rupture has been reported (very rare) – May be multiple as part of generalized angiomatosis (Klippel-Trenaunay-Weber syndrome) ○ Lymphangioma – Rare, slow-growing benign splenic neoplasm □ Most lymphangiomas occur in childhood – Can be either solitary or multiple, but often are subcapsular in location – Lymphangiomatosis: Diffuse lymphangiomas (usually in children) ○ Hamartoma – Rare benign tumor of spleen with autopsy incidence of 0.13% and female predominance □ Mass comprises disorganized vascular channels mixed with either splenic red pulp or white pulp – More common in tuberous sclerosis and WiskottAldrich syndrome ○ Sclerosing angiomatoid nodular transformation (SANT) – Rare benign splenic lesion representing abnormal stromal response to splenic insult with nodular transformation of splenic vascular bed – Most common in middle-aged female patients – Almost always incidental finding, but can result in splenomegaly and abdominal pain when large ○ Littoral cell angioma – Rare benign vascular neoplasm arising from littoral cells lining splenic sinuses of red pulp – No clear gender or age predilection reported ○ Angiomyolipoma (AML) – Extremely rare lesion usually in patients with tuberous sclerosis or multiple renal angiomyolipomas • Malignant tumors ○ Primary lymphoma (limited to spleen) – Most common malignant tumor of spleen, but much less common than secondary involvement of spleen by widespread lymphoma – Most often non-Hodgkin lymphoma (B-cell origin) – Can occur sporadically or in association with AIDS – More often affects younger population than secondary (widespread, nodal) lymphoma ○ Angiosarcoma – Very rare malignant tumor of spleen, but most common primary nonlymphoid vascular malignant tumor of spleen □ Seen sporadically and in patients with previous exposure to Thorotrast or other toxins

• Benign tumors ○ Hemangioma – Homogeneous solid or cystic mass which may be solitary or multiple □ Early peripheral and late central enhancement (classic peripheral nodular enhancement seen in hepatic hemangiomas often not present) □ Some lesions may demonstrate homogeneous hyperenhancement on arterial phase with persistent enhancement on delayed imaging □ May rarely be heterogeneous with cystic components, and large lesions may have central scar/necrosis (as with large hepatic hemangiomas) – Central punctate or peripheral curvilinear Ca++ may be present ○ Lymphangioma – Thin-walled, low-density or cystic lesions with sharply defined margins – Walls of lesions may show faint enhancement, but typically no wall thickening or nodularity – May demonstrate curvilinear peripheral calcification ○ Hamartoma – Small lesions appear as isodense or hypodense solid mass (which may have some internal cystic components) – Large lesions may demonstrate areas of density (scar or necrosis) or calcification and may distort splenic contour – Enhancement: Variable, but lesions appear more uniform on delayed scans – May rarely demonstrate calcification ○ Sclerosing angiomatoid nodular transformation (SANT) – Well-circumscribed, hypodense, solid mass which is hypodense on noncontrast and early phase imaging and gradually becomes isodense on delayed imaging ○ Littoral cell angioma – Multiple hypodense masses of varying size (few mm to several cm) – May demonstrate delayed enhancement ○ Angiomyolipoma – Fat density mass similar to appearance in kidney with variable internal enhancement depending on internal mixture of fat, smooth muscle, and vasculature • Malignant tumors ○ Lymphoma – Several imaging patterns including enlarged spleen without discrete mass, solitary dominant hypodense mass, or multifocal hypodense lesions □ Discrete masses or areas of infiltration usually hypoenhancing relative to normal spleen – Focal lesions common in AIDS-related lymphoma

Spleen

TERMINOLOGY

575

Spleen

Primary Splenic Tumors

– Lesions are classically homogeneously hypodense, but may rarely appear necrotic or cystic ○ Angiosarcoma – Splenomegaly with either solitary dominant mass or multiple lesions with irregular margins – Heterogeneous and variable enhancement: Individual lesions may superficially resemble hemangiomas – Spleen may appear heterogeneous due to hemorrhage and calcification – Propensity to bleed, with intrasplenic, subcapsular, or perisplenic hematoma possible – Frequent extensive liver or distant metastases

MR Findings • Benign tumors ○ Hemangioma – Hypointense on T1WI and brightly hyperintense on T2WI (similar to hepatic hemangiomas) – May show delayed enhancement, but classic peripheral nodular enhancement seen in hepatic hemangiomas often not present ○ Lymphangioma – Follow fluid signal: T2 hyperintense and T1 hypointense ○ Hamartoma – Isointense on T1WI and heterogeneously hyperintense on T2WI (but less T2 hyperintense compared to hemangiomas) – Heterogeneous early enhancement which may persist and become more homogeneous on delayed images ○ Sclerosing angiomatoid nodular transformation – Tend to be T2 hypointense with central scar ○ Littoral cell angioma – Multiple T1 hypointense and T2 hyperintense lesions – Lesions may demonstrate internal hemosiderin with hypointensity on T1WI and T2WI • Malignant tumors ○ Lymphoma – Typically low to intermediate signal on T1WI and mild to moderate high signal on T2WI – Lesions are hypoenhancing on all phases of imaging ○ Angiosarcoma – T1WI and T2WI: Variable signal due to hemorrhage, necrosis, and calcification (usually hypointense on T1WI and heterogeneously hyperintense on T2WI) – T1 C+: Variable or ring-like enhancement, but may show enhancement pattern similar to hemangiomas

Ultrasonographic Findings • Grayscale ultrasound ○ Hemangioma – Typically homogeneously hyperechoic (as in liver), but can appear complex with solid and cystic areas ○ Lymphangiomas – Multiloculated cystic appearance ± internal echoes ○ Hamartoma – Well-defined, homogeneous, and echogenic mass ○ Littoral cell angioma – Well-defined hypoechoic or isoechoic mass with multiple lesions frequent ○ Lymphoma 576

– Involved portions of spleen appear hypoechoic ○ Angiosarcoma – Solid mass with mixed echogenicity

Imaging Recommendations • CECT or MR

DIFFERENTIAL DIAGNOSIS Splenic Cyst • Sharply defined unilocular water density lesion in spleen (no enhancement, fluid signal on MR, anechoic on US) • Some cysts can have septations, trabeculations, thick wall, internal necrotic debris, or rim calcification

Splenic Hematoma • Irregular intraparenchymal fluid collection with variable density depending on acuity

Splenic Metastases and Lymphoma • Spleen often involved secondarily in lymphoma (nonHodgkin > Hodgkin disease) • Spleen is uncommon, but not rare site of metastasis ○ Isolated metastasis to spleen (in absence of metastatic disease elsewhere) is extremely rare

Splenic Infection and Abscess • May be pyogenic, parasitic, fungal (microabscesses), or due to tuberculosis

Granulomatous Disease • Small low-density splenic nodules in active phase, with lesions calcifying in chronic setting

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most benign splenic tumors are incidental findings on imaging studies performed for other reasons – May be rarely symptomatic due to size/mass effect ○ Splenic malignancies may present with LUQ pain, palpable mass, splenomegaly, fever, weight loss

Treatment • Suspicious tumors (based on either imaging or clinical history) should undergo biopsy ± splenectomy

DIAGNOSTIC CHECKLIST Consider • Appearance of most splenic tumors is nonspecific, and biopsy or splenectomy must be considered based on clinical history and degree of suspicion on imaging

SELECTED REFERENCES 1.

Thipphavong S et al: Nonneoplastic, benign, and malignant splenic diseases: cross-sectional imaging findings and rare disease entities. AJR Am J Roentgenol. 203(2):315-22, 2014

Primary Splenic Tumors Spleen

(Left) Axial CECT shows a multiloculated cystic mass with thin walls and nearwater-density contents, a typical appearance for a splenic lymphangioma. (Right) Axial CECT in an 18-year-old girl with splenomegaly shows innumerable near-waterdensity masses within the spleen, which is markedly enlarged as a result. The lesions have septations and subtle mural nodularity. Resection of the spleen revealed dozens of lymphangiomas.

(Left) Axial CECT shows a partially calcified splenic mass in a patient with left upper quadrant pain. No lymphadenopathy or other extrasplenic pathology was evident. This proved to be primary non-Hodgkin lymphoma. (Right) Axial T1 C+ FS MR demonstrates a large, centrally necrotic, hypervascular mass in the spleen, ultimately found to be a large splenic angiosarcoma. While the mass in the liver superficially resembles a hemangioma, the liver lesion was one of multiple metastases in this patient.

(Left) Axial CECT shows multiple hypodense lesions in the liver and spleen. Although they resemble hemangiomas with nodular enhancement, these were found to represent metastatic angiosarcoma. Note the additional metastases in the retroperitoneum and right lung base . (Right) Axial CECT shows a large, hypodense splenic mass . The size of the mass raised concern for malignancy and precipitated splenectomy, where the lesion was found to be sclerosing angiomatoid nodular transformation.

577

Spleen

Splenic Metastases and Lymphoma KEY FACTS

• Splenic metastases ○ Relatively uncommon with autopsy incidence of 7% ○ Most common pathway of spread is hematogenous via splenic artery, but can less commonly spread retrograde via splenic vein or direct splenic invasion ○ Most common primary sites of malignancy: Breast (21%), lung (18%), ovary (8%), stomach (7%), melanoma (6%) ○ Most common multiple lesions (~ 60% of cases) ○ Appearance varies depending on primary malignancy, but most commonly hypoattenuating and solid – Some metastases can appear "cystic" and be mistaken for cyst or abscess: Melanoma, breast, ovary, and endometrium ○ Almost always evidence of metastatic disease elsewhere: Isolated metastasis to spleen is extremely rare • Splenic lymphoma ○ Most common malignant tumor of spleen (secondary lymphoma is far more common than primary lymphoma)

(Left) Axial CECT demonstrates a solid, hypodense mass in the spleen. The lesion was discovered to be lymphoma at biopsy. No other disease was present elsewhere. This was a rare instance of primary splenic lymphoma. (Right) Axial CECT demonstrates a mixed cystic and solid mass centered in the spleen that was found to represent lymphoma. The cystic components within the mass are unusual prior to treatment, as lymphoma usually appears as a solid hypodense mass.

(Left) Coronal CECT in a patient with known lymphoma demonstrates a markedly enlarged spleen with innumerable tiny hypodense nodules throughout. This "miliary" pattern of disease is a common manifestation of splenic lymphoma. (Right) Axial CECT shows innumerable focal lesions in the liver and spleen. Liver biopsy confirmed non-Hodgkin lymphoma. Diffuse involvement of spleen (or liver) may be difficult to recognize on imaging, often appearing as nonspecific organomegaly.

578

○ Several possible imaging patterns, including enlarged spleen without discrete mass, solitary dominant mass, multifocal involvement with several discrete lesions, or innumerable tiny nodules – Involved regions of spleen typically appear hypodense, homogeneous, and poorly enhancing – Lesions can uncommonly demonstrate necrosis or cystic degeneration (usually after treatment) – Splenomegaly alone cannot be used to diagnose splenic involvement □ 30% of normal-sized spleens harbor tumor in lymphoma patients, and splenomegaly can be present without tumor

IMAGING

TOP DIFFERENTIAL DIAGNOSES • • • •

Primary splenic tumors Splenic infarction or infection/abscess Sarcoidosis Artifact

Splenic Metastases and Lymphoma

General Features • Key concepts ○ Splenic metastases – Relatively uncommon with autopsy incidence of 7% – Most common pathway of spread is hematogenous (via splenic artery), but can less commonly spread retrograde via splenic vein (portal HTN) and lymphatics – Most common primary sites of malignancy: Breast (21%), lung (18%), ovary (8%), stomach (7%), melanoma (6%), prostate (6%) □ Frequency of splenic metastases by primary tumor: Melanoma (34%), breast (12%), lung (9%) – Direct invasion of spleen may occur in gastric cancer, colon cancer, pancreatic tail cancer, left renal cell carcinoma, neuroblastoma, or retroperitoneal sarcoma – Serosal implants on surface of spleen: Ovarian, GI tract, pancreatic cancers ○ Splenic lymphoma – Most common malignant tumor of spleen □ Spleen can be involved by both Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) – Primary lymphoma far more rare than secondary lymphoma □ Accounts for only 1-2% of all cases of lymphoma □ Primary splenic lymphoma most often NHL (B-cell origin/diffuse large B cell) □ More commonly seen in younger patients compared to secondary lymphoma – Spleen commonly secondarily involved by lymphoma (i.e., lymphadenopathy or extranodal disease elsewhere) □ Spleen initially involved in 1/3 of HD and 30-40% of patients with NHL □ Spleen is considered "nodal" organ in HD and "extranodal" organ in non-Hodgkin lymphoma □ Splenic involvement can upstage disease in HD because it is considered a "nodal organ," while it is less likely to do so in NHL since spleen is usually involved in patients with widespread disease – AIDS-related lymphoma □ Histologic subtypes: Small noncleaved (Burkitt and non-Burkitt type) □ Splenic involvement: NHL more common than HD

CT Findings • Splenic metastases ○ Attenuation varies depending on primary malignancy type, but most commonly hypoattenuating and solid – Some can appear cystic (homogenously low density) and be mistaken for cyst or abscess: Melanoma, breast adenocarcinoma, ovary, and endometrium – May be multiple (~ 60%) or single (~ 30%) – Most metastases to spleen do not calcify except mucinous colon cancer ○ Almost always evidence of metastatic disease elsewhere: Isolated metastasis to spleen is extremely rare • Splenic lymphoma

○ Several possible imaging patterns – Homogeneously enlarged spleen without discrete mass □ Spleen may appear totally normal or appear diffusely hypodense and poorly enhancing (with loss of moire pattern on arterial phase imaging) □ Diffuse infiltration most common with HD – Solitary dominant mass – Multifocal involvement with several discrete lesions measuring 1-10 cm in size □ Focal lesions more likely in AIDS-related lymphoma – Miliary disease with innumerable tiny splenic nodules measuring < 5 mm ○ Involved regions of spleen typically appear hypodense, poorly enhancing on CECT, and relatively homogeneous – Although uncommon, lesions can rarely demonstrate necrosis or cystic degeneration (usually after treatment) – Calcifications are almost never present prior to treatment – Splenomegaly alone cannot be used to diagnose splenic involvement □ 30% of normal-sized spleens can harbor tumor in patients with lymphoma, and splenomegaly can be present without tumor infiltration □ Greatest degree of splenomegaly often seen with marginal zone lymphomas ○ Lymphadenopathy (abdominal or retroperitoneal) usually present – Splenic hilum lymphadenopathy is very common in NHL (59%), but uncommon in HD

Spleen

IMAGING

MR Findings • Splenic metastases ○ T1WI: Usually isointense to hypointense, although melanoma metastases may be hyperintense on T1WI due to melanin content ○ T2WI: Usually hyperintense ○ T1 C+: Enhancement depends on type of primary tumor, but most commonly hypoenhancing • Splenic lymphoma ○ Splenic lesions typically mildly hypointense on T1WI and mildly hyperintense on T2WI – Noncontrast conventional T1- and T2-weighted images may be insensitive for lymphoma due to similar T1 and T2 relaxation times of splenic tissue and lymphomatous deposits ○ Lesions are hypoenhancing to normal splenic parenchyma on T1WI C+ images (usually best visualized on venous or delayed phases)

Ultrasonographic Findings • Grayscale ultrasound ○ Splenic metastases – Lesions can vary in echogenicity (usually hypoechoic) □ "Target" or "halo" morphology should raise concern for metastasis – Echogenic lesions (rare): e.g., plasmacytoma, hepatoma, melanoma, prostate, and ovarian cancer ○ Splenic lymphoma – Typically diffuse or focal hypoechoic lesions which may have "target" morphology 579

Spleen

Splenic Metastases and Lymphoma

– Isolated splenic metastasis (i.e., metastasis to spleen in absence of metastatic disease elsewhere) is extraordinarily rare □ Isolated splenic metastases most often due to gynecologic malignancies ○ Splenic lymphoma – HD and NHL – Primary lymphoma (limited to spleen and usually NHL) much less common than secondary lymphoma

– Discrete lesions may not be visible, and spleen may appear heterogeneous or diffusely hypoechoic

Nuclear Medicine Findings • PET/CT ○ Sensitivity and specificity of PET/CT for splenic involvement by lymphoma are > 95% ○ Can present with either discrete FDG avid lesions or diffusely increased splenic FDG uptake (greater than liver and bone marrow uptake) ○ Should not be confused with increased splenic FDG uptake in setting of hematopoietic stimulating agents or in immediate post-therapy setting ○ High-grade lymphomas (Burkitt, diffuse large B-cell, anaplastic, grade III follicular, nodular sclerosing HD) tend to have greater FDG uptake than low-grade lymphomas

Imaging Recommendations • Best imaging tool ○ CECT

DIFFERENTIAL DIAGNOSIS Primary Splenic Tumors • Multiple different primary splenic tumors (hemangioma, lymphangioma, hamartoma, etc.), most of which have nonspecific imaging appearance • Degree of concern (and need for biopsy/splenectomy) should be based on clinical scenario and suspicious imaging features, but most primary splenic lesions are benign, incidental findings

Splenic Infarction • Wedge-shaped peripheral hypodense defect that does not appear mass-like

Splenic Infection and Abscess • May be pyogenic, parasitic, fungal (microabscesses), or due to tuberculosis • Pyogenic abscess typically appears as low-density lesion with thick, irregular enhancing wall • Fungal (e.g., Candida, Aspergillus, Cryptococcus) abscesses usually present as multiple, small, low-density lesions

Sarcoidosis • Hepatosplenomegaly with multiple, variably sized, hypodense nodules in liver and spleen • Often associated with upper abdominal lymphadenopathy • Presence of characteristic interstitial lung changes and mediastinal/hilar adenopathy can be clue to diagnosis

Artifact • Heterogeneous splenic enhancement ("moire" pattern) in arterial phase could theoretically mimic splenic tumor

PATHOLOGY General Features • Etiology ○ Splenic metastases: Multiple potential primary malignancies may metastasize to spleen – Usually seen in patients with widespread metastatic disease 580

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Splenic metastases – Most patients are asymptomatic – Symptoms may include LUQ pain, weight loss, palpable mass, or splenomegaly – Acute pain symptoms may occur in setting of splenic infarct due to tumor emboli/splenic vein thrombosis or splenic rupture due to tumor growth (very rare) ○ Splenic lymphoma – Fever, weight loss, night sweats, malaise, LUQ pain, palpable mass, splenomegaly

Demographics • Age ○ Primary splenic lymphoma: Younger age group than secondary lymphoma ○ Splenic metastases: Dependent on primary tumor type • Gender ○ HD: Younger age, M:F = 4:1; older age, M:F = 2:1 ○ NHL: M:F = 1.4:1

Natural History & Prognosis • Prognosis ○ Splenic metastases: Very poor prognosis, as patients typically have widely disseminated disease ○ Splenic lymphoma: Early stage (good); late stage (poor)

Treatment • Chemotherapy for systemic disease • Splenectomy for isolated splenic tumor

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Splenic size not reliable indicator of presence or absence of lymphomatous involvement • Isolated splenic lesion (in absence of metastatic disease elsewhere) is very unlikely to represent metastasis

SELECTED REFERENCES 1.

2. 3.

Thipphavong S et al: Nonneoplastic, benign, and malignant splenic diseases: cross-sectional imaging findings and rare disease entities. AJR Am J Roentgenol. 203(2):315-22, 2014 Caremani M et al: Focal splenic lesions: US findings. J Ultrasound. 16(2):6574, 2013 Karlo CA et al: Computed tomography of the spleen: how to interpret the hypodense lesion. Insights Imaging. 4(1):65-76, 2013

Splenic Metastases and Lymphoma Spleen

(Left) Axial CECT in a patient with non-Hodgkin lymphoma shows the spleen to be markedly enlarged with heterogeneous, hypoattenuating, discrete tumor foci . Note the lymphomatous infiltration in the adrenal gland and nodes throughout the abdomen . (Right) Coronal CECT in a patient with melanoma demonstrates innumerable metastases almost completely replacing the spleen, with an additional metastasis to the liver dome .

(Left) Axial CECT demonstrates a large, lowdensity splenic mass found to be a melanoma metastasis. Melanoma is one of several tumors which can appear cystic, as in this case, and be misinterpreted as a splenic abscess. (Right) Axial CECT in a patient with metastatic ovarian carcinoma shows loculated ascites or cystic peritoneal metastases that indent the surface of the liver and spleen . Some of the metastases are within the splenic parenchyma.

(Left) Axial CECT in a patient with breast cancer shows a splenic metastasis . Several liver metastases were also present (not shown). In most published reports, breast cancer is the most common primary source for splenic metastases. (Right) Axial CECT shows a hypervascular mass within the spleen that proved to be a metastatic focus from a gastric carcinoid tumor. Tumors arising from the tail of the pancreas or other LUQ organs should also be considered in the differential diagnosis for splenic tumors.

581

SECTION 9

Liver

Introduction and Overview Imaging Approach to the Liver

584

Congenital Congenital Hepatic Fibrosis AD Polycystic Liver Disease Congenital Absence of Hepatic Segments

590 594 598

Infection Hepatic Pyogenic Abscess Hepatic TB and Fungal Infections Hepatic Amebic Abscess Hepatic Hydatid Cyst Hepatic Schistosomiasis Viral Hepatitis

600 604 608 612 616 620

,QƮDPPDWLRQ Alcoholic Liver Disease Autoimmune Hepatitis Steatosis and Steatohepatitis Hepatic Injury From Toxins Cirrhosis Primary Biliary Cirrhosis )RFDO&RQƮXHQW)LEURVLV Nodular Regenerative Hyperplasia Regenerative and Dysplastic Nodules Solitary Necrotic Nodule Peribiliary Cysts

626 630 632 638 642 652 658 662 668 676 677

Metabolic or Inherited Glycogen Storage Disease Hemochromatosis Wilson Disease

678 680 684

Degenerative Hepatomegaly

688

Vascular Disorders 7UDQVLHQW+HSDWLF$WWHQXDWLRQRU,QWHQVLW\'LƪHUHQFH7+$'VDQG7+,'V  Arterioportal Shunt Portal Vein Occlusion Passive Hepatic Congestion Budd-Chiari Syndrome Venoocclusive Disease Hepatic Infarction Peliosis Hepatis Hereditary Hemorrhagic Telangiectasia HELLP Syndrome

690 696 700 706 710 716 718 722 726 732

Trauma Hepatic Trauma

736

Treatment Related Radiation-Induced Liver Disease Postoperative Changes, Liver Transjugular Intrahepatic Portosystemic Shunt (TIPS) Hepatic Transplantation

740 744 748 754

Benign Neoplasms and Tumor-Like Conditions Hepatic Cyst Hepatic Cavernous Hemangioma Focal Nodular Hyperplasia Hepatic Adenoma Biliary Hamartoma Hepatic Angiomyolipoma and Lipoma +HSDWLF,QƮDPPDWRU\3VHXGRWXPRU

764 772 780 786 794 798 802

Malignant Neoplasms Hepatocellular Carcinoma Fibrolamellar Carcinoma Peripheral (Intrahepatic) Cholangiocarcinoma Epithelioid Hemangioendothelioma Biliary Cystadenocarcinoma

806 814 820 826 832

Hepatic Angiosarcoma

838

8QGLƪHUHQWLDWHG6DUFRPD

842

Hepatic Metastases and Lymphoma

844

Liver

Imaging Approach to the Liver

Relevant Anatomy and Embryology Fibropolycystic Disorders Anomalies may occur during the embryologic development of the ductal plate that surrounds the portal vein in fetal life. Depending on the stage of fetal development at which these defects occur, a variety of common and uncommon abnormalities of the liver and biliary tree may result, including congenital hepatic fibrosis, polycystic liver disease, Caroli disease, and biliary hamartomas. Segmental Anatomy of the Liver The Couinaud system of defining liver segmental anatomy divides the liver into 8 segments by vertical planes that extend through the course of the hepatic veins and by a horizontal plane that extends through the right and left portal veins. Understanding this anatomy is particularly important because of recent advances in surgical and interventional therapy for liver disease.

CT and MR Protocols Scans that are intended to evaluate diffuse or focal hepatic disease must be multiphasic, with image acquisition at various times during and following the IV bolus of contrast medium. Noncontrast images (NECT or MR): For evaluation of steatosis and hemochromatosis, nonenhanced CT provides the best estimation of liver attenuation. For evaluation by MR, T1-weighted gradient-echo imaging with both in-phase and opposed-phase GRE sequences is essential; selective signal loss on opposed-phase MR is the best noninvasive means of diagnosing steatosis. In patients with hemochromatosis (or lesions with excess iron content, such as cirrhotic regenerative nodules), there is loss of parenchymal signal on the MR image with longer echo time, usually the in-phase image. NECT usually shows increased density (attenuation) of the liver in such patients, although effective therapy may reduce liver iron content and restore attenuation to normal. Early arterial phase imaging (18-25 sec): This is the best phase for depicting hepatic arterial anatomy, as it allows multiplanar and 3D reformations as CT or MR arteriography without interference from contrast-opacification of the portal vein. This phase, however, is usually not effective in detecting focal masses, even those that are hypervascular. Late arterial phase (35-45 sec): This is usually the optimal phase for depiction of hypervascular hepatic masses, such as hepatocellular carcinoma (HCC), focal nodular hyperplasia, or hypervascular metastases (e.g., those from primary endocrine malignancies). Portal venous (parenchymal) phase (60-70 sec): This is usually the optimal phase for depiction of most focal hepatic masses and for visualization of the hepatic and portal veins. It should be obtained in all abdominal and hepatic CT and MR protocols by itself or in addition to other phases. Delayed phase (5-10 min): This is useful to identify washout from hypervascular liver tumors, such as HCC. Conversely, cholangiocarcinoma and certain other lesions become more apparent due to delayed persistent enhancement on this phase. It is rarely necessary to obtain more than 3 phases of imaging for a particular patient, but the optimal combination of phases should be selected for maximum benefit for the disease process being evaluated. 584

Hepatobiliary MR Contrast Agents Most gadolinium-based IV contrast media act as nonspecific vascular and extracellular enhancing agents. They generally have the same effect on MR imaging of vessels and hepatic lesions as iodinated contrast medium for CECT. Therefore most focal hepatic lesions, which are hypovascular, will be detected as focal hypovascular foci on contrast-enhanced dynamic MR sequences. Hypervascular lesions, such as HCC, will be detected as transiently hyperenhancing lesions on late arterial phase images with subsequent washout. Several newer contrast agents have been introduced into clinical imaging that include a heterogeneous group of paramagnetic agents that are taken up in hepatocytes and excreted in bile; these are referred to collectively as "hepatobiliary MR contrast agents." The 2 most commonly used are gadobenate dimeglumine (MultiHance from Bracco in Milan, Italy) and gadoxetate (Eovist from Schering in Berlin, Germany). Gadoxetate (Eovist) has a much greater degree of hepatobiliary excretion (50%) than any other agents. The added benefit of these agents lies in their prolonged retention within functioning hepatocytes, which are present in benign lesions, such as FNH, but absent in metastases and most HCC. Gadolinium-based hepatobiliary MR agents are incorporated into sequential dynamic and delayed MR imaging with T1-weighted image.

Approach to Hepatic Disease and the Hepatic Mass Almost all detectable focal hepatic lesions appear hypodense relative to enhanced hepatic parenchyma. To render a clinically useful interpretation, it is necessary to characterize the lesion by imaging features and to then consider a list of differential diagnoses of lesions that may have these characteristics. The following is a recommended approach. First, define the liver itself and any lesions by their size, shape, vascularity, attenuation, or intensity on each phase of contrast enhancement. For example, hepatomegaly with diffuse low attenuation is usually due to steatosis or other infiltrative processes. A small liver with an enlarged caudate and small right lobe indicates cirrhosis or Budd-Chiari syndrome. Hepatic vein occlusion is usually the result of Budd-Chiari syndrome, hypercoagulable state, or tumor encasement. Portal vein occlusion is usually the result of portal hypertension, septic thrombophlebitis (e.g., diverticulitis), a hypercoagulable state, or tumor encasement or invasion. A mass that is hypo- or isodense with the liver on NECT and transiently hyperdense (intense) on arterial phase imaging is a "hypervascular" lesion with a limited differential diagnosis. Focal lesions that washout to become hypodense (hypointense) on parenchymal or delayed phase are usually malignant tumors, while lesions that become isodense (isointense) may be neoplastic or vascular in origin. A focal lesion that is hyperdense (hyperintense) only on delayed imaging has a very limited differential diagnosis, essentially limited to lesions with an extensive fibrous stroma such as cholangiocarcinoma, focal confluent fibrosis, treated tumors, and the central scar of a focal nodular hyperplasia or a fibrolamellar carcinoma. These principles apply to CT and MR using conventional contrast agents as opposed to hepatobiliary contrast-enhanced MR.

Imaging Approach to the Liver

Other specific descriptors that help to characterize an hepatic lesion include the presence or absence of calcification, scar, hemorrhage, capsule, etc.

Fat-Containing Liver Mass Common • Steatosis (fatty liver) (mimic) • Pericaval fat deposition Less Common • Hepatocellular carcinoma • Hepatic adenoma • Hepatic metastases • Hepatic angiomyolipoma • Alcohol-ablated liver tumors (mimic) • Fat within hepatic surgical defect (mimic)

Clinical correlation is always critical to the reasonable interpretation of imaging studies, and this should be incorporated into the analysis of hepatic imaging. An example of how one might interpret a CT scan of a hepatic mass might be: "Arterial phase enhanced CT shows a spherical, homogeneously enhancing, 5 cm mass with a small central scar in segment 4 of the liver. The mass is nearly isoattenuating to normal liver on nonenhanced and portal venous phase images. In a young woman with no evidence of history of cirrhosis or extrahepatic malignancy, this likely represents a focal nodular hyperplasia. If additional confirmation is felt to be warranted, MR evaluation with a hepatobiliary contrast agent is recommended."

Rare but Important • Teratoma or liposarcoma • Focal nodular hyperplasia • Xanthomatous lesions in LCH

Differential Diagnosis

Less Common • Hepatic hydatid cyst • Metastases and lymphoma, hepatic • Biliary cystadenocarcinoma • Hepatic candidiasis • Caroli disease • Intrahepatic pseudocyst • Cholangiocarcinoma (mucin-producing variant)

Liver Mass With Central or Eccentric Scar Common • Focal nodular hyperplasia • Hepatic cavernous hemangioma Less Common • Fibrolamellar hepatocellular carcinoma • Hepatocellular carcinoma • Cholangiocarcinoma (peripheral) • Hepatic adenoma • Hepatic metastases • Epithelioid hemangioendothelioma Focal Liver Lesion With Hemorrhage Common • Hepatic trauma • Hepatic adenoma • Hepatocellular carcinoma • Hepatic cyst • AD polycystic disease, liver Less Common • Coagulopathic hemorrhage, liver • Hepatic metastases • HELLP syndrome Liver "Mass" With Capsular Retraction Common • Focal confluent fibrosis • Cholangiocarcinoma (peripheral) • Metastases and lymphoma, hepatic • Hepatocellular carcinoma • Peritoneal metastases (mimic) Less Common • Epithelioid hemangioendothelioma • Hepatic cavernous hemangioma • Primary sclerosing cholangitis • Inflammatory pseudotumor, liver

Liver

Shape is another useful descriptor in determining the nature of a hepatic mass. Most benign and malignant neoplasms are round (spherical), while lesions that have a wedge (pyramidal) shape usually have a vascular etiology, such as a transient hepatic attenuation (or intensity) difference (THAD or THID). Geographic focal steatosis can also have a wedge shape, often for the same reason, which is focally disordered hepatic metabolism due to altered vascularity.

Cystic Hepatic Mass Common • Hepatic cyst • AD polycystic disease, liver • Hepatic pyogenic abscess • Hepatic amebic abscess • Biliary hamartoma • Biloma/seroma • Steatosis (fatty liver) (mimic)

Focal Hypervascular Liver Lesion Common • Hepatic cavernous hemangioma • Focal nodular hyperplasia • Arterio-portal shunt • Transient hepatic attenuation difference (THAD) • Hepatocellular carcinoma • Hepatic metastases • Hepatic adenoma • Hepatic AV malformation (Osler-Weber-Rendu) Less Common • Nodular regenerative hyperplasia • Fibrolamellar hepatocellular carcinoma • SVC obstruction, abdominal manifestations • Cholangiocarcinoma (peripheral) • Peliosis hepatis • Angiosarcoma, liver Multiple Hypodense Liver Lesions Common • Metastases and lymphoma, hepatic • Simple hepatic cysts • Hepatic cavernous hemangioma • Multifocal fatty infiltration • Hepatic pyogenic abscess • AD polycystic disease, liver • Hepatocellular carcinoma • Hepatic sarcoidosis Less Common • Hepatic adenoma 585

Liver

Imaging Approach to the Liver

• • • • •

Hepatic amebic abscess Hepatic hydatid cyst Hepatic candidiasis Biliary hamartomas Nodular regenerative hyperplasia

Rare but Important • Hepatic angiomyolipoma • Epithelioid hemangioendothelioma • Caroli disease Liver Lesion With Capsule or Halo on MR Common • Hepatic metastases • Hepatic pyogenic abscess • Hepatocellular carcinoma • Hepatic hematoma Less Common • Hepatic adenoma • Hepatic hydatid cyst • Hepatic amebic abscess • Focal nodular hyperplasia • Nodular regenerative hyperplasia Focal Hyperdense Hepatic Mass on Nonenhanced CT Common • Cirrhotic regenerating nodule • Any mass in fatty liver (mimic) • Focal sparing in fatty liver • Hepatic metastases • Hepatic hematoma Less Common • Hemorrhage within hepatic tumor: Hepatic adenoma, hepatocellular carcinoma • Calcification within primary hepatic tumor: Hepatic cavernous hemangioma, fibrolamellar HCC • "Hepatic pseudotumor": Budd-Chiari syndrome, primary sclerosing cholangitis • HELLP syndrome Periportal Lucency or Edema Common • Dilated bile ducts (mimic) • Systemic hypervolemia

(Left) Graphic shows 4 sections that depict the 8 segments of the liver, which are separated by vertical planes through the hepatic veins and a horizontal plane through the portal vein. (Right) The sections in this axial CECT correspond to levels in the previous graphic. The liver segments are numbered. The falciform ligament plane separates the medial (segment 4) from the lateral (segments 2 and 3) left lobe. Segment 3 is not shown.

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• • • •

Passive hepatic congestion Hepatitis (acute) Ascending cholangitis Post-transplant liver: Biliary necrosis (posttransplantation), lymphedema (post-transplantation • Hepatic trauma Less Common • Porta hepatis lymphadenopathy • Cirrhosis: Peribiliary cysts • Portal vein thrombosis • Primary sclerosing cholangitis • Steatosis (fatty liver) • AIDS cholangiopathy • Hepatocellular carcinoma • Cholangiocarcinoma • Hepatic metastases and lymphoma • Cholangitis, chemotherapy-induced • Cholangitis, recurrent pyogenic Widespread Low Attenuation Within Liver Common • Steatosis (fatty liver) Less Common • Hepatitis • Toxic hepatic injury • Hepatic infarction • Hepatic metastases and lymphoma • Hepatic sarcoidosis • Opportunistic intestinal infections • Hepatocellular carcinoma • Wilson disease • Radiation hepatitis • Budd-Chiari syndrome • Glycogen storage disease

Imaging Approach to the Liver Liver

(Left) CT arteriogram shows conventional hepatic arterial anatomy. This coronal reformation shows both hepatic arteries arising from the proper hepatic artery , which in turn arises from the common hepatic artery . (Right) MR angiogram in the venous phase shows the hepatic and portal vein branches. Some of the intravenously injected contrast medium is still circulating through the arteries, resulting in enhancement of the aorta .

(Left) In this previously healthy young woman with RUQ pain and hypotension, CECT shows a brightly enhancing mass that has ruptured, causing massive hemorrhage with a sentinel clot . This is essentially diagnostic of an hepatic adenoma. (Right) This man with known cirrhosis presented with acute pain and hypotension. A coronal CECT image shows an encapsulated mass , ascites, and sentinel clot indicating rupture of the mass, essentially diagnostic of HCC in this setting.

(Left) This 18-year-old girl had a hepatic mass discovered incidentally on CT. In-phase T1W MR shows a uniformly hyperintense mass with a thin capsule . (Right) An opposed-phase T1W MR image in the same case shows signal dropout from the mass , indicating the presence of lipid within the lesion. This, along with the presence of a capsule in a young, otherwise healthy woman is essentially diagnostic of hepatic adenoma.

587

Liver

Imaging Approach to the Liver

(Left) Axial CECT shows a geographic area of low attenuation throughout the anterior and medial segments in this patient with multifocal steatosis. In addition there are spherical and oval lesions in other segments of the liver. The hepatic vessels course through the low-density lesions without being displaced or occluded. (Right) Axial CECT arterial phase (A) and parenchymal phase (B) show multiple THAD lesions due to portal venous branch occlusions from metastases .

(Left) Venous phase CT of a young man with a palpable epigastric mass shows the mass as a lobulated, homogeneous lesion that is slightly hyperdense to underlying liver. Considering FNH the most likely diagnosis, MR with gadoxetate (Eovist) enhancement was recommended. (Right) 20minute delayed phase MR image shows persistent enhancement of the mass , indicating the presence of functioning hepatocytes but disordered biliary drainage, findings considered diagnostic of FNH.

(Left) CECT shows a liver mass with innumerable septations, and slightly higher than water density contents. While a neoplastic mass could not be excluded by imaging characteristics alone, the appearance is more suggestive of infection. Needle aspiration yielded pus, and a catheter was inserted for drainage. (Right) Arterial phase CT shows a large hypervascular pancreatic tail mass and innumerable hypervascular liver lesions , typical of metastases from a malignant neuroendocrine tumor of the pancreas.

588

Imaging Approach to the Liver Liver

(Left) Arterial phase CECT shows multiple foci of hypervascularity within a cirrhotic liver in this patient with classic hypervascular HCC. (Right) Portal venous (parenchymal) phase in the same patient shows washout of enhancement , typical of hypervascular malignant hepatic tumors. Metastases could have an identical appearance but are rare within a cirrhotic liver.

(Left) NECT shows a hypodense "mass" in the anterior and medial segments of a cirrhotic liver in a patient with focal confluent fibrosis. Note the wedge shape and overlying retraction of the hepatic capsule. (Right) Delayed phase CT in the same patient shows that the lesion has become hyperdense to the remaining liver. While cholangiocarcinoma could have a similar appearance, the diagnosis of focal confluent fibrosis is much more likely given the clinical and radiographic evidence of alcoholic cirrhosis.

(Left) Portal venous phase CECT shows a large mass in the liver with heterogeneous enhancement, capsular retraction , and obstruction of the intrahepatic bile ducts in this patient with intrahepatic (peripheral) cholangiocarcinoma. (Right) Delayed phase image in the same patient shows persistent hyperdense enhancement of most of the tumor . The combination of findings is essentially diagnostic of cholangiocarcinoma.

589

Liver

Congenital Hepatic Fibrosis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Part of a spectrum of congenital abnormalities resulting in variable degrees of fibrosis and cystic anomalies of liver and kidneys ○ 1 manifestation of fibropolycystic liver disease

• • • •

IMAGING

CLINICAL ISSUES

• Biliary hamartomas, polycystic liver disease, choledochal cyst, and Caroli disease ○ Often coexist in same patient • CT or MR: Enlarged dysmorphic liver, left lobe hypertrophy, right lobe atrophy ○ size and number of hepatic arteries ○ May develop hypervascular, benign, large, regenerative nodules (nodular regenerative hyperplasia) ○ T2WI bright lesions: Hepatic cysts, biliary hamartomas, dilated bile ducts (Caroli disease) ○ Varices, ascites, splenomegaly

• Congenital hepatic fibrosis is always present in patients with autosomal recessive polycystic kidney disease (ARPKD) ○ Sometimes with autosomal dominant PKD • Congenital hepatic fibrosis is variable in severity, age at presentation, and clinical manifestations ○ Portal hypertension is usually present by adolescence • Diagnosis: Coexisting hepatic and renal cysts ○ Liver biopsy • Treatment for moderate to severe fibrosis: Transplantation (hepatic and renal)

(Left) Low-power view shows marked portal expansion and numerous irregularly shaped bile ducts . The lobular architecture in adjacent parenchyma is well maintained with normal central veins . (Courtesy H. Wang, MD, PhD.) (Right) Axial CECT in a young woman with congenital fibropolycystic disease shows a dysmorphic, heterogeneous liver with several large cystic lesions, representing cystic and fusiform dilation of biliary tree (Caroli disease); note the central dot sign of Caroli disease.

(Left) Axial CECT in a 40-yearold woman shows numerous cysts within the liver, many with the central dot sign that represents the portal vein branches around which the biliary cystic spaces of Caroli disease are wrapped. This patient had biopsy-proven congenital hepatic fibrosis, which results in hepatic failure and accounts for splenomegaly . (Right) Coronal CECT in the same patient shows the cystic bile ducts of Caroli disease with large supernumerary hepatic arteries and a renal allograft .

590

Isolated polycystic liver disease Primary sclerosing cholangitis Caroli disease Isolated biliary hamartomas

Congenital Hepatic Fibrosis

Abbreviations • Congenital hepatic fibrosis (CHF)

Definitions • Part of a spectrum of congenital abnormalities resulting in variable degrees of fibrosis and cystic anomalies of liver and kidneys • 1 manifestation of fibropolycystic liver disease

IMAGING

MR Findings

Liver

TERMINOLOGY

• MR cholangiography (MRC) ○ Bile ducts; variable pattern: Normal, irregular dilation, Caroli pattern ○ ± biliary hamartomas (small T2-hyperintense "cysts") • Associated polycystic disease liver/kidney ○ T1WI: Hypointense ○ T2WI bright lesions: Hepatic cysts, biliary hamartomas, dilated bile ducts (Caroli disease) ○ T1 C+: No enhancement of cysts ○ Heavily T2WI: signal intensity due to pure fluid content

General Features

Ultrasonographic Findings

• Best diagnostic clue ○ Dysmorphic liver with cysts, abnormal ducts, + signs of portal hypertension – May show similar changes within kidneys • Location ○ Both lobes of liver • Size ○ Hepatic cystic size varies based on severity of CHF • Other general features ○ CHF is always present in patients with autosomal recessive polycystic kidney disease (ARPKD) and sometimes present with autosomal dominant PKD ○ 2 constant features of ARPKD – Kidney: Tubular ectasia, cysts, and fibrosis – Liver: Fibrosis (dilated bile ducts, enlarged/fibrotic portal triads) and multiple cysts □ All patients with ARPKD have findings of hepatic fibrosis on biopsy □ Not all patients with hepatic fibrosis have ARPKD ○ Relative severity of disease may vary – Renal or hepatobiliary disease may predominate ○ Variants of fibropolycystic liver disease – CHF, biliary hamartomas, polycystic liver disease, choledochal cyst, and Caroli disease often coexist in same patient ○ Hepatic fibrosis that exists separately from other liver and renal diseases is very rare

• Grayscale ultrasound ○ Moderate to severe hepatic fibrosis – Bile ducts: Moderate to severe dilatation – Liver and spleen: Enlarged – Splenic and portal veins: Dilated – Portal triads: Distinct echogenicity ○ Associated polycystic disease liver and kidney – Uncomplicated: Anechoic lesions, smooth borders, no defined walls – Complicated: Septations, internal echoes, wall thickening – Biliary hamartomas: Often echogenic, not simpleappearing cysts • Color Doppler ○ Depicts collaterals/direction and velocity of blood flow in splenic/portal veins – Direction: Hepatofugal or hepatopetal

Radiographic Findings • ERCP ○ ± dilatation of intrahepatic bile ducts

• Irregular strictures/dilation of intra-/extrahepatic bile ducts • Often leads to cirrhotic, dysmorphic liver • Often associated with inflammatory bowel disease

CT Findings

Caroli Disease

• Mild CHF ○ Liver may appear normal • Moderate to severe fibrosis ○ Bile ducts: Normal to irregularly dilated ○ Enlarged dysmorphic liver, left lobe hypertrophy, right lobe atrophy ○ Splenomegaly and varices ○ Increased size and number of hepatic arteries ○ May develop hypervascular, benign, large, regenerative nodules (nodular regenerative hyperplasia) – Similar to those seen in Budd-Chiari syndrome • Associated polycystic disease of liver and kidney ○ Multiple hypodense (water density) hepatic and renal cysts of varied size ○ CECT: No enhancement of cyst contents

• Simple type ○ Cystic dilatation of bile ducts without periportal fibrosis • Periportal type (Caroli syndrome) ○ Ductal dilatation + cysts + periportal fibrosis ○ Indistinguishable from congenital hepatic fibrosis • Best imaging clue on CECT ○ Enhancing tiny dot (portal radicle) within dilated cystic intrahepatic ducts

Imaging Recommendations • Best imaging tool ○ Multiplanar/multiphase CECT or MR

DIFFERENTIAL DIAGNOSIS Isolated Polycystic Liver Disease • May have autosomal dominant polycystic liver disease without CHF

Primary Sclerosing Cholangitis

Biliary Hamartoma • Innumerable cystic nodules < 1.5 cm in both lobes of liver • May exist as isolated anomaly or as part of fibropolycystic syndrome

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Liver

Congenital Hepatic Fibrosis

General Features • Etiology ○ Embryological: Ductal plate malformation – Abnormal bile duct formation and resorption • Genetics ○ Sporadic or autosomal recessive inheritance pattern ○ Probably linked to gene on chromosome 6p • Associated abnormalities ○ 100% of patients with ARPKD have CHF – Some patients with autosomal dominant PKD have hepatic fibrosis ○ Medullary sponge kidney (tubular ectasia) ○ Caroli disease, vaginal atresia, tuberous sclerosis ○ Juvenile nephronophthisis ○ Meckel-Gruber syndrome – Rare lethal, multisystem, autosomal recessive disorder affecting liver and kidneys (fibrosis and cysts), lungs, brain, and other organs ○ Pathophysiology – Periportal fibrosis portal hypertension (HTN) hepatosplenomegaly esophageal varices – Periportal fibrosis: Fetal type (more common), adult type (rare)

Gross Pathologic & Surgical Features • Liver: Normal, enlarged, or lobulated; dilated bile ducts/cysts

Microscopic Features • Periportal fibrosis; malformed, dilated, nonobstructive bile ducts

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Mild hepatic fibrosis: Asymptomatic ○ Moderate to severe fibrosis – Childhood type (more common), adult type (rare) – Portal HTN; hepatosplenomegaly; bleeding varices • Clinical profile ○ CHF is variable in severity, age at presentation, and clinical manifestations – Portal hypertension is usually present by adolescence • Lab ○ Usually normal liver function tests ○ ± leukopenia, thrombocytopenia, anemia – Due to hypersplenism • Diagnosis ○ Coexisting hepatic and renal cysts ○ Liver biopsy

Demographics • Age ○ Usually diagnosed in children (age 5-13 years) but rarely delayed until adulthood • Gender ○ M=F • Epidemiology 592

○ Reported incidence varies due to many degrees of expression

PATHOLOGY

Natural History & Prognosis • Rare developmental malformation of ductal plate • Hepatic fibrosis ○ Predominant features may include intrahepatic bile duct dilation &/or periportal fibrosis • Variable in age of onset, severity, and clinical presentation • Complications ○ Biliary: Cholangitis, obstruction, sepsis ○ Portal: Hypertension and bleeding varices ○ Cholangiocarcinoma in ~ 1%, usually in adult without ARPKD • Prognosis ○ Early intervention – Slow progress or arrest of disease – Increased life expectancy and quality of life ○ Those who survive childhood – Relatively good prognosis and survive into midlife

Treatment • Options ○ Mild hepatic fibrosis (asymptomatic): No treatment ○ Hypersplenism: Splenectomy ○ Moderate to severe fibrosis – Variceal sclerotherapy – Portosystemic shunting (TIPS) – Liver transplantation (cures renal and hepatic disease)

DIAGNOSTIC CHECKLIST Consider • Multiphasic/multiplanar CT or MRC ○ To detect early stage of CHF ○ To differentiate communicating/noncommunicating biliary abnormalities • Hepatic fibrosis, polycystic disease (liver and kidney), Caroli disease, and biliary hamartomas can occur in isolation or in any combination

Image Interpretation Pearls • No further evaluation needed in child with hepatic ductal dilatation, enlarged, fibrotic portal tracts, and hepatic and renal cysts

SELECTED REFERENCES 1.

2. 3.

4. 5. 6.

Hartung EA et al: Autosomal recessive polycystic kidney disease: a hepatorenal fibrocystic disorder with pleiotropic effects. Pediatrics. 134(3):e833-45, 2014 Vajro P et al: Management of adults with paediatric-onset chronic liver disease: strategic issues for transition care. Dig Liver Dis. 46(4):295-301, 2014 O'Brien K et al: Congenital hepatic fibrosis and portal hypertension in autosomal dominant polycystic kidney disease. J Pediatr Gastroenterol Nutr. 54(1):83-9, 2012 Venkatanarasimha N et al: Imaging features of ductal plate malformations in adults. Clin Radiol. 66(11):1086-93, 2011 Brancatelli G et al: Fibropolycystic liver disease: CT and MR imaging findings. Radiographics. 25(3):659-70, 2005 Lonergan GJ et al: Autosomal recessive polycystic kidney disease: radiologicpathologic correlation. Radiographics. 20(3):837-55, 2000

Congenital Hepatic Fibrosis Liver

(Left) Axial T2WI MR shows innumerable tiny bright foci throughout the liver, representing biliary hamartomas. Note one of the larger lesions . (Right) Axial T1WI C+ MR in the same patient shows enlarged and supernumerary hepatic arteries feeding a dysmorphic liver, a common sign of congenital hepatic fibrosis.

(Left) Axial CECT shows a dysmorphic liver with fusiform ectasia of the intrahepatic bile ducts . The left hepatic lobe is markedly enlarged, and the right lobe is atrophic. Note the innumerable small hypodense lesions as well, probably representing biliary hamartomas. (Right) Axial CECT in the same patient shows numerous enlarged abnormal hepatic artery branches . The kidneys are scarred and small. Biopsy proved hepatic and renal fibrosis.

(Left) T2WI MR shows multiple hepatic and renal manifestations of fibropolycystic disease. Note the massive enlargement of the left hepatic lobe and a small right lobe. There are innumerable tiny bright cystic lesions in the liver, which are biliary hamartomas. Note two of the larger lesions . (Right) T2WI MR in the same patient shows enlargement of the left hepatic lobe and a small right lobe. Note the position of the gallbladder . The kidneys are small and contain innumerable small cysts.

593

Liver

AD Polycystic Liver Disease KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Part of fibropolycystic liver (and renal) disease spectrum

• Liver progressively enlarges as it is replaced by cysts • Massive hepatomegaly, compression of stomach, bowel, lungs • Dull abdominal pain, abdominal distention, dyspnea, cachexia, early satiety • Liver function is uncommonly impaired • Treatment: Alcohol ablation, resection or marsupialization of dominant cysts ○ Orthotopic liver transplantation has excellent long-term results ○ Usually performed to relieve mass effect of liver on adjacent organs

IMAGING • Extent of hepatic involvement ranges from scattered cysts to diffuse replacement of liver ○ ± cysts in kidneys and other organs • Cyst contents often greater than water density/intensity due to hemorrhage (infection less common) ○ Calcification in cyst wall often seen due to old hemorrhage

TOP DIFFERENTIAL DIAGNOSES • Hepatic (bile duct) cysts • Biliary hamartomas ○ Usually numerous and < 15 mm in diameter • Caroli disease • Cystic metastases

(Left) Gross pathology photograph of a hepatectomy specimen shows numerous cysts replacing liver parenchyma. The cysts ranged in size from microscopic to 5 cm in greatest dimension and contained clear fluid. This liver, which weighed 9 kg, was resected due to intractable patient discomfort and pressure on other organs. (Right) Coronal T2WI MR shows innumerable high signal intensity cysts of varying size almost completely replacing hepatic parenchyma. Multiple cysts within the left kidney are also visible.

(Left) Axial CECT shows typical findings of AD polycystic liver disease (ADPLD) in a middleaged man with early satiety. Note the compression of the stomach by a dominant cyst from the left hepatic lobe, which was subsequently marsupialized at surgery with resolution of symptoms. (Right) Axial CECT in the same patient following surgical drainage of the left lobe cyst shows no residual compression of the stomach . The symptoms of early satiety also resolved.

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DIAGNOSTIC CHECKLIST • Cannot diagnose AD polycystic liver disease just by presence of numerous hepatic cysts ○ Requires cysts in other organs, family history, or genetic testing

AD Polycystic Liver Disease

Ultrasonographic Findings

• Autosomal dominant polycystic liver disease (ADPLD) or adult PLD

• Grayscale ultrasound ○ Anechoic masses with smooth borders, thin walls, and no septations or mural nodularity ○ Acoustic enhancement beyond each cyst

Definitions

Imaging Recommendations

• Uncommon inherited disorder • Part of fibropolycystic liver disease spectrum ○ Constitutes group of related lesions of liver and biliary tract caused by abnormal development of embryological ductal plate

• Best imaging tool ○ CECT or MR (renal function permitting) – MR is more sensitive for detection of complicated cysts

Abbreviations

IMAGING General Features • Best diagnostic clue ○ Multiple (> 20) cysts of varying size • Location ○ Extent of hepatic involvement ranges from limited sporadic areas of cystic disease to diffuse involvement of all lobes of liver – ± cysts in kidneys and other organs • Size ○ Range from < 1 mm to > 12 cm • Key concepts ○ Numerous large or small cysts coexist with fibrosis – Round or oval shape – Smooth, thin wall (if uncomplicated) – Absence of internal structures (if uncomplicated)

CT Findings • NECT ○ Multiple to innumerable, homogeneous, and hypoattenuating cystic lesions – Cyst contents > water density due to hemorrhage (infection less common) – Calcification in cyst wall often seen (due to old hemorrhage) • CECT ○ No wall or content enhancement ○ Cysts complicated by infection or hemorrhage may have septations &/or internal debris – May also have enhancement of walls, but no enhancing nodules ○ Cysts may contain fluid levels

MR Findings • T1WI ○ Uncomplicated cysts have very low signal intensity – Higher signal in cysts with recent hemorrhage • T2WI ○ Hetero- or homogeneous high signal intensity cysts – Intracystic hemorrhage: Lower signal intensity • T1WI C+ ○ Nonenhancing after administration of gadolinium contrast material • MR cholangiography (MRC) ○ No communication between cysts or with biliary tree ○ Coexisting Caroli disease will have cysts communicating with bile ducts

Liver

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Hepatic (Bile Duct) Cysts • Not reliably distinguishable by imaging or histology from ADPLD ○ Less likely to have hemorrhage • Multiple cysts of different sizes

Biliary Hamartoma • Usually numerous small lesions ○ Typically < 1.5 cm in diameter • Varied enhancement based on cystic/solid components of lesions ○ Predominantly cystic (water density) lesions – No enhancement of contents ○ Predominantly solid (fibrous stroma) lesions – Enhance and become isodense with liver parenchyma – Imparts echogenicity of smaller lesions • T2WI, MRC: Markedly hyperintense cyst-like lesions, no communication with biliary tree

Caroli Disease • Congenital communicating cavernous ectasia of biliary tract • Multiple, small, rounded, saccular dilatation of intrahepatic bile ducts • Central dot sign on CECT ○ Enhancing portal radicles within cysts • MRC: Communicating bile duct abnormality

Cystic Metastases • Often from sarcomas, especially GIST after treatment • Have internal debris or mural nodularity • Rarely as numerous as in polycystic liver

PATHOLOGY General Features • Etiology ○ Due to ductal plate malformation of small intrahepatic bile ducts – Ducts lose communication with biliary tree • Genetics ○ Autosomal dominant ○ Gene responsible for polycystic liver disease – PRKCSH (chromosome 19p) • Associated abnormalities ○ Biliary hamartomas ○ Congenital hepatic fibrosis ○ Caroli disease 595

Liver

AD Polycystic Liver Disease ○ Often coexists with autosomal dominant or recessive polycystic renal disease ○ Hepatic cysts are pathologically identical to simple or bile duct cysts

Gross Pathologic & Surgical Features • Progressive with massive enlargement and distortion of liver ○ Liver surrounding cysts frequently contains biliary hamartomas and fibrous tissue

Microscopic Features • Cuboidal and flat monolayer epithelium with no dysplasia in cyst walls

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Dull abdominal pain ○ Abdominal distention ○ Dyspnea ○ Cachexia; early satiety • Clinical profile ○ Other signs/symptoms – Often causes massive hepatomegaly, compression of stomach – Liver volume is often 5-10x higher than normal ○ Compression of portal vein portal hypertension ○ Extrinsic compression of intrahepatic bile ducts ○ Hepatic venous outflow obstruction due to compression by cysts ○ Transudative ascites, portal hypertension due to distortion of portal venules by cysts and fibrosis ○ Lab data: ADPLD uncommonly affects liver function

Demographics • Age ○ Adult manifestation • Gender ○ M 20 cm in diameter. Only a few small renal cysts are evident. The right kidney was displaced caudally and was hydronephrotic due to compression of the renal pelvis (not shown).

(Left) Axial NECT shows innumerable homogeneous and hypoattenuating cystic lesions with smooth, thin walls and an absence of internal structures. Some cysts have higher than water density contents and others have peripheral calcification in cyst walls due to prior episodes of intracystic hemorrhage. (Right) Axial CECT shows a liver that is grossly enlarged and nearly replaced by innumerable cysts. Note also the involvement of both kidneys. Most patients with PLD also have ADPKD.

(Left) T1WI GRE opposedphase image shows numerous hepatic cysts of varying intensity. Some are nearly black , as one would expect for simple fluid content, while others are of intermediate intensity. At least 1 has septations and heterogeneous contents from prior hemorrhage. (Right) T2WI MR in the same patient shows the complex nature of the contents of some of the hepatic cysts, with uncomplicated cysts being homogeneously bright and complex cysts having heterogeneous contents .

597

Liver

Congenital Absence of Hepatic Segments KEY FACTS

TERMINOLOGY • Agenesis or hypoplasia of hepatic lobes or segments • Lobar agenesis or hypoplasia is an uncommon developmental anomaly with absence of liver tissue to right or left of gallbladder fossa without prior surgery or disease

IMAGING • Most common segments involved ○ Right lobe: Segments 5 and 8 (anterior segments) ○ Left lobe: Segment 4

TOP DIFFERENTIAL DIAGNOSES • Acquired atrophy with cirrhosis ○ Atrophy of anterior and medial segments commonly follows development of focal confluent fibrosis in cirrhosis ○ Look for signs of portal hypertension (varices, ascites, etc.) • Postsurgical resection

(Left) Axial CECT shows a very small medial segment lying between the falciform ligament cleft and the gallbladder . The anterior segments are also small. (Right) Axial CECT in the same case shows the colon and omental fat filling the gap between the right and left hepatic lobes in the same patient with congenital hypoplasia of the anterior and medial segments.

(Left) Axial CECT shows hypoplasia of the anterior and medial segments. Note a clip from a prior cholecystectomy; the gallbladder normally lies in the interlobar plane. Also note the lateral and cephalic herniation of the stomach and colon . (Right) Axial NECT of a more caudal section in the same patient shows the large gap created by congenital hypoplasia of the anterior and medial segments. The gap is filled with omental fat and the hepatic flexure of the colon .

598

○ For hepatic resection, incisions can be made along longitudinal or transverse scissurae or both combined • Post chemoembolization or ablation ○ Hyperattenuation of atrophic liver parenchyma ○ Check prior imaging studies and medical records for evidence of prior tumor and treatment

CLINICAL ISSUES • Usually asymptomatic

DIAGNOSTIC CHECKLIST • Conditions including cirrhosis, atrophy secondary to biliary obstruction, hepatic surgery, and trauma can mimic agenesis and should be ruled out 1st

Congenital Absence of Hepatic Segments

Synonyms • Agenesis or hypoplasia of hepatic lobes or segments

Definitions • Lobar agenesis or hypoplasia is an uncommon developmental anomaly with absence of liver tissue usually to right or left of gallbladder fossa without prior surgery or disease

IMAGING General Features • Best diagnostic clue ○ Absence of right or left hepatic vein, portal vein and its branches, and intrahepatic ducts – If none of these structures are visible, agenesis is substantiated • Location ○ Most common segments involved – Right lobe: Segments 5 and 8 (anterior segments) – Left lobe: Segment 4 • Size ○ Compensatory hypertrophy of remaining segments

CT Findings • Altered topography of upper abdomen • Right lobar agenesis: Absence of liver tissue to right of main interlobar plane ○ Absence of right hepatic vein, portal vein and its branches, and right intrahepatic ducts ○ Lateral and "deep" position of gallbladder ○ High position of hepatic flexure of colon; right side, horizontal migration of stomach ○ Direct contact of inferior vena cava with posterior surface of medial segment of left lobe • Agenesis of left lobe: Absence of liver tissue to left of main interlobar plane ○ No apparent fissure of falciform ligament ○ Stomach and splenic flexure of colon migrate superiorly and medially ○ High position of duodenal bulb/U-shaped stomach

Other Modality Findings • Cholangiography: Absence or hypoplasia of ducts in affected segment

Imaging Recommendations • Best imaging tool ○ CT is most commonly used • Protocol advice ○ Multiplanar CECT shows altered anatomy best

DIFFERENTIAL DIAGNOSIS Cirrhosis • Atrophy of anterior and medial segments commonly follows development of focal confluent fibrosis in cirrhosis • Look for signs of portal hypertension (varices, ascites)

Postsurgical Resection

Liver

TERMINOLOGY

• For hepatic resection, incisions can be made along longitudinal or transverse scissurae, or both combined

Post Chemoembolization or Ablation • Atrophic liver parenchyma may appear hypo- or hyperattenuating • Check prior imaging studies and medical records for evidence of prior tumor and treatment

PATHOLOGY General Features • Etiology ○ Right lobe – Either failure of right portal vein to develop or error in mutual induction between septum transversum (primitive diaphragm) and endodermal diverticulum (primitive liver) ○ Left lobe – Extension of obliterative process that closes ductus venosus to left branch of portal vein • Associated abnormalities ○ Usually an isolated anomaly ○ Absence or hypoplasia of ipsilateral hemidiaphragm ○ Absence of inferior vena cava ○ Intestinal malrotation, choledochal cyst, agenesis of gallbladder, intrahepatic venovenous shunt

Gross Pathologic & Surgical Features • Unusual enlargement of remaining segments, resultant displacement of gallbladder, and change in axis of fissure of ligamentum venosum

CLINICAL ISSUES Presentation • Discovered incidentally on imaging studies • Biliary tract disease, volvulus of stomach

Demographics • Epidemiology ○ Incidence of lobar agenesis: 0.005% of 19,000 autopsy cases – ~ 42 cases of right lobe agenesis reported in literature

Natural History & Prognosis • Usually asymptomatic • Calculus formation and biliary malignancy are very rare

DIAGNOSTIC CHECKLIST Consider • Conditions including cirrhosis, atrophy secondary to biliary obstruction, hepatic surgery, and trauma can mimic agenesis and should be ruled out 1st

SELECTED REFERENCES 1.

Cho SK et al: Ischemic liver injuries after hepatic artery embolization in patients with delayed postoperative hemorrhage following hepatobiliary pancreatic surgery. Acta Radiol. 52(4):393-400, 2011

599

Liver

Hepatic Pyogenic Abscess KEY FACTS

TERMINOLOGY • Localized collection of pus in liver due to bacterial infection with destruction of hepatic parenchyma

• Infarction in liver allograft • Hepatic hydatid cyst • Biliary cystadenocarcinoma

IMAGING

PATHOLOGY

• CT: Multiseptate mass or cluster of smaller cystic masses ○ Nonliquefied infection may simulate neoplasm ○ Often accompanied by transient hepatic attenuation difference (THAD) due to hyperemia and thrombophlebitis of portal vein branch ○ Gas present in < 20% of pyogenic abscesses ○ Right lower lobe atelectasis and pleural effusion • US ○ Anechoic (50%), hyperechoic (25%), hypoechoic (25%) ○ ± debris, acoustic enhancement, or shadow

• Prevalent causes in Western countries ○ Diverticulitis or ascending cholangitis

TOP DIFFERENTIAL DIAGNOSES • Hepatic metastases • Hepatic amebic abscess

(Left) Schematic illustration shows peripheral multiloculated collections of pus within the surrounding inflamed liver. (Right) Axial CECT in this 33-year-old woman with a pyogenic abscess shows a multiseptate complex mass . Note the straight line demarcation of the hyperenhancing right hepatic lobe, a transient hepatic attenuation difference (THAD) due to the hyperemic wall of the abscess, and occlusion of the posterior right portal vein by thrombophlebitis (not shown).

(Left) CECT shows a liver mass with rim enhancement and central necrosis. The findings are compatible with neoplasm or abscess. (Right) Sonography in the same case shows a complex fluidcontaining mass (cursors) with acoustic enhancement .A US-guided needle aspiration yielded a small amount of pus, and a catheter was placed over a guidewire into the abscess. A repeat CT scan 2 months later showed substantial resolution of the abscess (not shown).

600

CLINICAL ISSUES • ~ 90% of all liver abscesses are pyogenic • Older patient with fever, RUQ pain, tender hepatomegaly, WBC • Treatment: Percutaneous aspiration + parenteral antibiotics (> 90% success)

DIAGNOSTIC CHECKLIST • Ablation or transarterial chemotherapy of liver tumor may cause necrosis with release of gas ○ May be indistinguishable from abscess by imaging alone

Hepatic Pyogenic Abscess

Definitions

PATHOLOGY

• Localized collection of pus in liver due to bacterial infection with destruction of hepatic parenchyma

IMAGING General Features • Best diagnostic clue ○ Multiseptate mass or cluster of smaller cystic masses

CT Findings • CECT ○ Sharply defined, spherical, hypodense mass – Nonliquefied infection may enhance and simulate neoplasm ○ May be multiseptate or cluster of smaller abscesses – Rim, capsule, and septal enhancement – Gas present in < 20% of pyogenic abscesses ○ Often accompanied by transient hepatic attenuation difference (THAD) due to hyperemia and thrombophlebitis of portal vein branch ○ Right lower lobe (RLL) atelectasis, pleural effusion

General Features • Etiology ○ Pyogenic abscess can develop via 5 major routes – Biliary: Ascending cholangitis – Portal vein: Pylephlebitis □ In descending order of frequency: Diverticulitis, appendicitis, proctitis, or inflammatory bowel disease □ Bacterial seeding of mesenteric veins carries bacteria to liver – Hepatic artery: Septicemia – Direct extension □ e.g., perforated gastric or duodenal ulcer – Traumatic: Blunt or penetrating injuries, including surgery ○ Prevalent causes in Western countries – Diverticulitis or ascending cholangitis – Infected infarcted tissue (post liver transplant, necrotic tumor)

CLINICAL ISSUES

MR Findings • T2WI ○ Variably hyperintense mass ○ High signal intensity perilesional edema • T1WI C+ ○ Hypointense pus in center ○ Rim or capsule enhancement ○ Small abscesses < 1 cm – May show homogeneous enhancement

Ultrasonographic Findings • Grayscale ultrasound ○ Irregular hypoechoic/mildly echogenic wall ○ Echogenicity of abscesses – Anechoic (50%), hyperechoic (25%), hypoechoic (25%) – ± septa or fluid level within abscess – Brightly echogenic foci with posterior artifact = gas – ± debris and posterior enhancement

Imaging Recommendations • Best imaging tool ○ CECT

Presentation • Clinical profile ○ Middle-aged/elderly patient with history of fever, RUQ pain, tender hepatomegaly, WBC • Diagnosis by fine-needle aspiration

Demographics • Epidemiology ○ ~ 90% of all liver abscesses are pyogenic ○ incidence in Western countries due to ascending cholangitis and diverticulitis

Treatment • Percutaneous aspiration + parenteral antibiotics (> 90% success)

DIAGNOSTIC CHECKLIST Consider • Clinical presentation and imaging allow confident diagnosis in most cases

Image Interpretation Pearls

DIFFERENTIAL DIAGNOSIS Hepatic Metastases • Usually not clustered or septate cystic mass

• Ablation of transarterial chemotherapy of liver tumor may cause necrosis with release of gas ○ May be indistinguishable from abscess by imaging alone

SELECTED REFERENCES

Hepatic Amebic Abscess • Peripheral, round, nonseptate; solitary (85%)

1.

Infarction in Liver Allograft • Hepatic artery thrombosis

Liver

• No surrounding inflammatory changes

TERMINOLOGY

hepatic and biliary necrosis

Hepatic Hydatid Cyst

2. 3.

Kuo SH et al: Mortality in Emergency Department Sepsis score as a prognostic indicator in patients with pyogenic liver abscess. Am J Emerg Med. 31(6):916-21, 2013 Alsaif HS et al: CT appearance of pyogenic liver abscesses caused by Klebsiella pneumoniae. Radiology. 260(1):129-38, 2011 Benedetti NJ et al: Imaging of hepatic infections. Ultrasound Q. 24(4):26778, 2008

• Large cystic liver mass, peripheral "daughter" cysts

Biliary Cystadenocarcinoma • Rare, multiseptate, water density cystic mass 601

Liver

Hepatic Pyogenic Abscess

(Left) Axial CECT in a 37-yearold woman who presented with a history of recurrent episodes of cholangitis demonstrates considerable dilation of the intrahepatic ducts , which also contain gas . A multiloculated pyogenic abscess is also noted . (Right) Coronal MRCP in the same patient reveals massive dilation of the intrahepatic and proximal extrahepatic bile ducts ,a type 4 choledochal cyst, responsible for the ascending cholangitis and abscess.

(Left) Axial CECT of an older woman with RUQ pain and fever following arterial chemoembolization for HCC shows high-density retained ethiodized oil (Lipiodol) within the treated tumor. There is a collection of gas and fluid at the center of the mass that was aspirated and proved to be an infected, necrotic tumor. (Right) Axial NECT of an elderly patient with diverticulitis and RUQ pain shows a spherical collection of gas and fluid , an abscess due to infectious thrombophlebitis from diverticulitis.

(Left) Axial CECT in a 46-yearold man who had a recent cholecystectomy shows an abscess containing gas and fluid within the liver and the gallbladder bed. (Right) Transverse ultrasound in the same patient shows a complex fluid collection , which yielded pus from a US-guided pigtail catheter drainage. Two weeks later, the patient was clinically well and required no further treatment, though a residual liver mass was still present.

602

Hepatic Pyogenic Abscess Liver

(Left) Axial CECT of a 41-yearold man with fever and a tender epigastric mass shows a complex cystic mass that contains small foci of gas . Note the straight line demarcation of the hyperemic left lobe (THAD) due to the abscess and narrowing of the left portal vein . (Right) CT in the same patient shows a typical "cluster of grapes" or multiseptate appearance of this pyogenic abscess as well as the left lobar THAD . Thrombophlebitis and abscess were due to diverticulitis.

(Left) Axial contrast-enhanced T1WI MR shows a complex multiseptate mass with hypointense contents and enhancing septa. (Right) Axial T2WI MR in the same patient shows a multiloculated abscess with heterogeneous fluid content that is variably hyperintense , with other foci of lower intensity reflecting the proteinaceous nature of the pus.

(Left) NECT shows a cluster of adjacent masses in the liver that have contents ranging in attenuation from near water to over 100 HU. On needle aspiration, blood-tinged purulent material was found and drained via pigtail catheter. (Right) Axial CECT shows multiple abscesses with gas-fluid levels following a Whipple procedure for pancreatic carcinoma. A USguided pigtail catheter placement was effective in draining and resolving the abscess.

603

Liver

Hepatic TB and Fungal Infections KEY FACTS

TERMINOLOGY

PATHOLOGY

• Opportunistic infection of liver (± other viscera), usually by fungal or mycobacterial organisms

• Originates from intestinal seeding of portal venous circulation • Candida albicans: Most common cause of fungal microabscesses

IMAGING • Best diagnostic clue: Multiple well-defined, rounded microabscesses in liver • Best imaging tools: US, CT, MR • Protocol advice ○ MR: FLASH sequences ○ Gadolinium enhancement required to detect very small lesions

TOP DIFFERENTIAL DIAGNOSES • • • •

Metastases Lymphomatous/leukemic foci in liver Biliary hamartomas Caroli disease

(Left) High-power view of hepatic miliary tuberculosis shows a granuloma with focal eosinophilic granular necrotic material and several multinucleated giant cells . (Courtesy J. Misdraji, MD.) (Right) Axial CECT of a woman with breast cancer, fever, and liver dysfunction demonstrates multiple small, low-density lesions due to hepatic candidiasis. Metastases would uncommonly be so numerous and small.

(Left) Axial CECT in a patient undergoing chemotherapy for acute leukemia, now presenting with a fever, demonstrates fungal abscesses due to Candida. Note the multiple small (< 1 cm) lesions in all lobes of the liver. (Right) Axial CECT of a 33-year-old woman with non-Hodgkin lymphoma presenting with a recent spike in temperature shows innumerable tiny hypodense lesions in the liver and spleen due to candidiasis. Lymphomatous parenchymal involvement is rarely detected as such small discrete lesions.

604

CLINICAL ISSUES • Most common signs/symptoms ○ Asymptomatic or abdominal pain and fever ○ Erythematous papules on skin • Clinical profile: Immunocompromised patient recovering from neutropenia ○ High incidence in transplant patients with fungal colonization

DIAGNOSTIC CHECKLIST • Rule out other innumerable hypodense liver lesions • Biopsy specimen for histology/microbiology

Hepatic TB and Fungal Infections

Definitions • Opportunistic infection of liver (± other viscera), usually by fungal or mycobacterial organisms

IMAGING General Features • Best diagnostic clue ○ Multiple well-defined, rounded microabscesses in liver

Biliary Hamartomas • Benign congenital malformation of bile ducts • Sharply defined lesions < 15 mm in diameter • Asymptomatic, incidental finding

Caroli Disease • Central dot sign ○ Enhancing tiny dot (portal radicle) within dilated cystic intrahepatic ducts on CECT

PATHOLOGY

CT Findings

General Features

• CECT ○ Biphasic CT may be more accurate than venous phase only – Nonenhancing hypodense centers – ± peripheral rim enhancement ○ Central or eccentric "dot" felt to represent hyphae

• Etiology ○ Originates from intestinal seeding of portal venous circulation ○ Candida albicans: Most common cause of fungal microabscesses • Associated abnormalities ○ AIDS, leukemia, lymphoma, transplant recipients ○ Underlying malignancy ○ Neutropenia due to other causes – Chemotherapy – Radiation therapy

MR Findings • T2WI ○ Hyperintense • T1WI C+ ○ Hypointense lesions ± enhancing rim • Contrast-enhanced FLASH (fast low-angle shot) images ○ Detects more lesions

Ultrasonographic Findings • Grayscale ultrasound ○ 4 major patterns of hepatic candidiasis – Uniformly hypoechoic □ Most common appearance (fibrosis and debris) – Echogenic □ Scar formation – "Wheel within wheel" (early stage) □ Peripheral zone surrounds inner echogenic "wheel," which surrounds central hypoechoic nidus – "Bull's eye" (as WBC return to normal) □ 1-4 mm lesion with hyperechoic center surrounded by hypoechoic rim ○ After antifungal therapy: Lesions increase in echogenicity, decrease in size, often disappear altogether

Liver

TERMINOLOGY

CLINICAL ISSUES Presentation • Clinical profile ○ Immunocompromised patient recovering from neutropenia ○ High incidence in transplant patients with fungal colonization

Natural History & Prognosis • Prognosis usually good with prompt diagnosis and treatment

Treatment • Antifungal therapy (amphotericin B and fluconazole) in large doses required for disseminated form ○ Lesions may disappear on CT and US during neutropenia and antifungal therapy ○ Therapy should not be discontinued on basis of imaging alone

Imaging Recommendations • Best imaging tool ○ US, CT, or MR • Protocol advice ○ MR: FLASH sequences ○ Gadolinium enhancement to detect very small lesions

DIFFERENTIAL DIAGNOSIS Metastases • Larger, less numerous; spleen usually not involved • Epithelial metastases: Rim enhancement

Lymphomatous/Leukemic Foci in Liver • Less well defined, less numerous, larger • Foci are also seen in spleen

DIAGNOSTIC CHECKLIST Consider • Rule out other innumerable hypodense liver lesions • Biopsy specimen for histology/microbiology

SELECTED REFERENCES 1. 2.

3. 4. 5.

Simon J et al: Echinocandins in invasive candidiasis. Mycoses. 56(6):601-9, 2013 Yellapu RK et al: Education and Imaging. Hepatobiliary and pancreatic: Candida liver abscesses associated with endocarditis. J Gastroenterol Hepatol. 25(5):1017, 2010 Kim HJ et al: Isolated perihepatic tuberculosis: imaging findings. Clin Radiol. 64(2):184-9, 2009 Amarapurkar DN et al: Hepatobiliary tuberculosis in western India. Indian J Pathol Microbiol. 51(2):175-81, 2008 Benedetti NJ et al: Imaging of hepatic infections. Ultrasound Q. 24(4):26778, 2008

605

Liver

Hepatic TB and Fungal Infections

(Left) Axial CECT of a 28-yearold man with acute leukemia shows several small, spherical, hypodense, hepatic lesions that have a peculiar appearance of alternating concentric circles of hypodense and hyperdense rings; biopsy confirmed candidiasis. Other fungal infections or metastases could have a similar appearance. (Right) More caudal CECT section in the same patient shows an additional focal lesion , one of many that were present. Biopsy confirmed Candida abscesses.

(Left) Sagittal US of a 28-yearold man with acute leukemia, fever, and abnormal liver function shows one of many small hypoechoic lesions with a central echogenic dot ("bull's eye") and acoustic enhancement . (Right) Transverse US of the same patient shows additional lesions, including smaller lesions that have central echogenic foci and throughtransmission indicative of fluid content. Thin-needle USguided aspiration confirmed Candida infection.

(Left) Axial CECT of a 43-yearold man with cirrhosis and fever shows signs of cirrhosis and portal hypertension. Also seen are multiple small lesions with hypodense centers and hyperenhancing rims or capsules. (Right) A more caudal CECT section in the same patient shows a cirrhotic morphology with a nodular surface, widened fissures, and caudate hypertrophy, along with additional discrete, rimenhancing lesions . USguided biopsy confirmed Candida microabscesses.

606

Hepatic TB and Fungal Infections Liver

(Left) Axial CECT in a man with leukemia shows innumerable small, hypodense lesions in the liver and spleen. The causative organism in this case was Mycobacterium aviumintracellulare. (Right) Axial T2WI MR in an immunosuppressed patient reveals innumerable high signal fungal (Candida) abscesses .

(Left) Axial CECT of a 40-yearold man with fever and night sweats shows innumerable focal liver lesions, most of which have a brightly enhancing rim and hypodense center . Biopsy proved hepatic tuberculosis. (Right) Axial NECT in the same patient shows punctate calcification in some of the lesions , a typical finding of healed granulomas of tuberculosis or fungal (usually histoplasmosis) origin.

(Left) Transverse grayscale sonogram of hepatic candidiasis shows multiple small, "target" lesions as well as slightly larger hypoechoic abscesses . (Right) Transverse ultrasound in an immunosuppressed patient shows multiple small, hypoechoic masses from hepatic Candida lesions, some with a bull's-eye appearance.

607

Liver

Hepatic Amebic Abscess KEY FACTS

IMAGING • CT: Solitary, peripheral, round or ovoid mass ○ Higher than water density, nonenhancing contents ○ Rim or capsular enhancement ○ Often see transient hepatic attenuation difference (THAD) due to thrombophlebitis of portal vein and hyperemia of abscess capsule • US: Abuts liver capsule with hetero- or homogeneous internal echoes, distal acoustic enhancement • Associated right-sided atelectasis and pleural effusion

TOP DIFFERENTIAL DIAGNOSES • Post-treatment metastases (cystic or necrotic) • Hepatic pyogenic abscess ○ Cluster sign: Small abscesses coalesce into single septate cavity • Hepatic hydatid cyst ○ Numerous peripheral "daughter" cysts • Biliary cystadenocarcinoma

(Left) Graphic demonstrates a unilocular encapsulated mass with "anchovy paste" consistency of contents. (Right) Axial CECT obtained in a 27-year-old man, who presented with a fever and RUQ pain on returning from a vacation to Mexico, illustrates an abscess with a zone of peripheral low-density edema surrounding the hyperdense capsule , characteristic findings for a hepatic amebic abscess.

(Left) Longitudinal grayscale ultrasound of the right lobe of the liver in a 41-year-old woman who presented with a fever and RUQ pain demonstrates a hypoechoic mass with diffuse low-level echoes . (Right) Axial CECT in the same patient illustrates a large amebic abscess with a "shaggy" internal wall and a peripheral zone of edema . As in this case, most (85%) amebic abscesses are solitary and in the right hepatic lobe.

608

○ No surrounding inflammatory changes

CLINICAL ISSUES • RUQ pain, tender hepatomegaly, diarrhea with mucus • Serum indirect hemagglutination positive in > 90% of cases • High-risk groups in Western countries ○ Recent immigrants ○ Institutionalized ○ Homosexuals • > 90% respond to antimicrobial therapy • < 10% require aspiration or drainage

DIAGNOSTIC CHECKLIST • Imaging, clinical features, and serology allow diagnosis in almost all cases ○ Aspiration and drainage are rarely necessary for diagnosis or treatment

Hepatic Amebic Abscess

Definitions • Localized collection of pus in liver due to Entamoeba histolytica with destruction of hepatic parenchyma

IMAGING General Features • Best diagnostic clue ○ Peripherally located, sharply defined, round, hypodense mass with enhancing capsule • Location ○ Right lobe (72%) > left lobe (13%) ○ Usually peripheral • Size ○ 85% are solitary lesions; size from 1-10 cm

CT Findings • CECT ○ Unilocular or multilocular lesions ○ Enhancement of peripheral rim or capsule ○ Often see THAD due to thrombophlebitis of portal vein & hyperemia of abscess capsule ○ Extrahepatic abnormalities – RLL atelectasis, right pleural effusion, empyema – Colonic wall may be thickened (amebic colitis)

Ultrasonographic Findings • Grayscale ultrasound ○ Round/oval, sharply defined, hypoechoic mass ○ Abuts liver capsule with hetero- or homogeneous internal echoes, distal acoustic enhancement

DIFFERENTIAL DIAGNOSIS Post-Treatment Metastases (Cystic or Necrotic) • Usually no elevation of diaphragm or atelectasis • No fever or increased WBC

Hepatic Pyogenic Abscess • Simple pyogenic abscess ○ Cluster sign: Small abscesses coalesce into single septate cavity

Hepatic Hydatid Cyst • Large, well-defined, cystic liver mass • Numerous peripheral "daughter" cysts • May show curvilinear or ring-like pericyst calcification

Biliary Cystadenocarcinoma • Rare, multiseptated, water density cystic mass • No surrounding inflammatory changes • Contains solid, enhancing, mural, or septal nodules

• Associated abnormalities ○ Amebic colitis

Liver

TERMINOLOGY

Gross Pathologic & Surgical Features • Usually solitary abscess with dark, reddish-brown fluid with consistency of anchovy paste

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ RUQ pain, tender hepatomegaly, diarrhea with mucus • Lab data ○ Serum indirect hemagglutination positive in 90% of cases

Demographics • Age ○ Any age group • Epidemiology ○ Most common extraintestinal manifestation of amebic infestation ○ ~ 10% of world population is infected with E. histolytica ○ High-risk groups in Western countries – Recent immigrants, institutionalized patients, homosexual men

Natural History & Prognosis • Complications ○ Pleuropulmonary amebiasis (20-35%) – Pulmonary consolidation or abscess – Effusion, empyema, or hepatobronchial fistula • Prognosis ○ Good with amebicidal therapy ○ Mortality rate in USA < 3% – < 1% when confined to liver – 6% if extends into chest

Treatment • > 90% respond to antimicrobial therapy ○ Metronidazole or chloroquine ○ < 10% require aspiration or drainage • Percutaneous drainage happens when ○ Unable to differentiate from pyogenic abscess or tumor ○ Patient is pregnant ○ Bacterial superinfection is present

DIAGNOSTIC CHECKLIST Consider • Imaging, clinical features, and serology allow diagnosis in almost all cases

SELECTED REFERENCES

PATHOLOGY

1.

General Features

2.

• Etiology ○ Entamoeba histolytica ○ Primary mode of infection: Human carriers pass amebic cysts into stool ○ May become secondarily infected with pyogenic bacteria

3. 4.

Congly SE et al: Amoebic liver abscess in USA: a population-based study of incidence, temporal trends and mortality. Liver Int. 31(8):1191-8, 2011 Gunther J et al: Short report: Amebiasis-related mortality among United States residents, 1990-2007. Am J Trop Med Hyg. 85(6):1038-40, 2011 Benedetti NJ et al: Imaging of hepatic infections. Ultrasound Q. 24(4):26778, 2008 Mortelé KJ et al: The infected liver: radiologic-pathologic correlation. Radiographics. 24(4):937-55, 2004

609

Liver

Hepatic Amebic Abscess

(Left) Axial CECT shows a large, "shaggy" cystic liver mass with nonenhancing contents, representing a typical amebic abscess as well as occlusion of the anterior branch of the right portal vein , causing increased arterial flow to the affected segment of the liver. (Right) Axial CECT in the same patient shows hyperperfusion of the anterior right lobe . This transient hepatic attenuation difference (THAD) is due to increased arterial blood flow induced by the abscess and the right portal vein occlusion.

(Left) Axial NECT in a 65-yearold man with recent travel history + RUQ pain and fever shows a complex, poorly encapsulated mass in the right hepatic lobe . (Right) Sagittal US in the same patient shows a large, spherical mass . The contents are very heterogeneous and echogenic, with little apparent posterior acoustic enhancement . Thick brown material was aspirated; culture confirmed an amebic abscess.

(Left) Axial CECT shows multiple large and small lowdensity, encapsulated, intrahepatic lesions . Note the rim enhancement in some lesions . (Right) CT from the same patient shows additional amebic abscesses , each with a discrete capsule . It is unusual to encounter this many amebic abscesses in a patient.

610

Hepatic Amebic Abscess Liver

(Left) Axial CECT of a 35-yearold Hispanic man with fever and RUQ pain shows a lowdensity, encapsulated mass in the dome of the liver. Note the right pleural effusion . (Right) US of the same patient shows low-level echoes within the cystic mass + acoustic enhancement . Most amebic abscesses are single or few in number, while pyogenic abscesses are clustered and multiple. Fungal abscesses are even more numerous and usually appear as innumerable "microabscesses" in the liver &/or spleen.

(Left) Axial CECT of a 42-yearold man whose only travel history was to Hawaii shows a large, poorly defined heterogeneous hepatic mass that was aspirated and found to have thick pus from amebic infection. (Right) Axial CECT in the same patient shows a thick-walled appendix arising from the cecum , with localized ascites . At surgery, the appendix appeared to be thickened and chronically inflamed; an appendectomy was performed.

(Left) A more caudal CT section in the same patient shows more of the ascites adjacent to the cecum . (Right) Photographs of the cross sections of the resected appendix and light microscopy revealed chronic appendicitis with amebic infection of the wall of the appendix, presumably the source of the hepatic amebic abscess.

611

Liver

Hepatic Hydatid Cyst KEY FACTS

IMAGING • Echinococcus granulosus: Most common cause of hydatid disease ○ Large, unilocular/multilocular, well-defined, hypodense cysts ○ Contains multiple internal "daughter" cysts of lower density than "mother" cyst (exocyst) ○ Curvilinear ring-like calcification of pericyst (wall) ○ Calcified wall: Usually indicates no active infection if completely circumferential ○ Dilated intrahepatic bile duct: Due to compression or rupture of cyst into bile ducts ○ US: Multiseptate cyst with "daughter" cysts and echogenic material between cysts ○ Water lily sign: Cyst with floating, undulating membrane and detached endocyst • Echinococcus multilocularis (alveolaris): Less common but aggressive, tumor-like form

(Left) Graphic shows a hydatid cyst within the liver with a peripheral fibrous capsule (pericyst) and numerous ""daughter" cysts within. (Right) Gross photograph of liver shows a hydatid cyst containing multiple "daughter" cysts . The fibrous rim or pericyst can be seen surrounding the cyst. (Courtesy K. Caradine, MD.)

(Left) This 29-year-old woman emigrated to the USA from Jordan. Axial CT shows a classic spherical mass, exophytic from the left lobe of the liver. Note the thick, fibrotic wall (pericyst) and the presence of peripheral "daughter" cysts within the larger cyst. (Right) A coronalreformatted CT image from the same patient clearly demonstrates the "daughter" cysts within the larger "mother" cyst (exocyst). A similar lesion was present within the left hepatic lobe (not shown).

612

○ Extensive, infiltrative cystic and solid masses of low density (14-40 HU) ○ Margins are irregular and ill defined ○ Simulates primary or secondary malignant tumor

TOP DIFFERENTIAL DIAGNOSES • Biliary cystadenocarcinoma ○ Rare, solitary, multiseptate, water density cystic mass • Hepatic pyogenic abscess ○ "Cluster of grapes": Confluent complex cystic lesions • "Cystic" metastases • Hemorrhagic or infected cyst

CLINICAL ISSUES • Cysts: Initially asymptomatic • Symptomatic with in size or cyst rupture ○ Rupture into biliary tree, peritoneal or pleural cavity is not rare

Hepatic Hydatid Cyst

DIFFERENTIAL DIAGNOSIS

Synonyms

Biliary Cystadenocarcinoma

• Echinococcal or hydatid disease

• Rare, solitary, multiseptate, water density cystic mass ○ Septa and peripheral wall enhance, may calcify

IMAGING General Features • Key concepts ○ Echinococcus granulosus: Most common cause of hydatid disease – Up to 60% of cysts are multiple ○ Echinococcus multilocularis (alveolaris): Less common but aggressive, tumor-like form

CT Findings • CECT ○ E. granulosus – Uni- or multilocular, well-defined cysts – Contain multiple peripheral "daughter" cysts of lower density than "mother" cyst – Curvilinear ring-like calcification of pericyst (wall) □ Usually indicates no active infection if completely circumferential – Enhancement of cyst wall and septa – Dilated intrahepatic bile duct (IHBD) □ Due to compression or rupture of cyst into ducts ○ E. multilocularis (alveolaris) – Extensive, infiltrative cystic and solid masses of low density (14-40 HU) – Margins are irregular and ill defined – Amorphous type of calcification – Simulates primary or secondary malignant tumor – Minimal enhancement of noncalcified portions

MR Findings • T1WI ○ Rim (pericyst): Hypointense (fibrous component) ○ "Mother" cyst (hydatid matrix) – Usually intermediate signal intensity ○ "Daughter" cysts: Less signal intensity than "mother" cyst (matrix) • T2WI ○ Rim (pericyst): Hypointense (fibrous component) ○ 1st echo T2WI: Increased signal intensity – "Mother" cysts more than "daughter" cysts ○ Strong T2WI: Hyperintense – "Mother" and "daughter" cysts have same intensity

Ultrasonographic Findings • Grayscale ultrasound ○ E. granulosus – Predominately anechoic cyst with hydatid "sand" – Multiseptate cyst with "daughter" cysts and echogenic material between cysts (characteristic) – Water lily sign: Cyst with floating, undulating membrane and detached endocyst – Densely calcified mass (echogenic and shadowing)

Liver

TERMINOLOGY

Hepatic Pyogenic Abscess • "Cluster of grapes": Confluent complex cystic lesions

"Cystic" Metastases • Metastatic sarcoma or ovarian carcinoma most common

Hemorrhagic or Infected Cyst • Complex cystic, heterogeneous mass • Septations, fluid levels, and mural nodularity • Calcification may be seen

PATHOLOGY General Features • Etiology ○ Caused by 2 types of parasites – E. granulosus and E. multilocularis ○ Hydatid disease – Caused by larval stage of E. granulosus tapeworm ○ Definitive host: Dog or fox ○ Intermediate host: Human, sheep, or wild rodents ○ Germinal layer (endocyst) scolices larval stage ○ Larvae portal vein liver (75%) – Lungs (15%), other tissues (10%)

CLINICAL ISSUES Presentation • Diagnosis ○ Serologic tests positive in > 80% of cases ○ Percutaneous aspiration of cyst fluid – Danger of peritoneal spill and anaphylactic reaction

Natural History & Prognosis • Complications ○ Compression, infection, or rupture into biliary tree ○ Rupture into peritoneal or pleural cavity ○ Spread of lesions to lungs, heart, brain, and bone • Prognosis ○ E. granulosus: Good, with treatment ○ E. multilocularis: Fatal within 10-15 years if untreated and poor, even with treatment

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • "Daughter" cysts can float freely within "mother" cyst ○ Altering patient's position may change position of "daughter" cysts

SELECTED REFERENCES 1. 2.

El Malki HO et al: Radical versus conservative surgical treatment of liver hydatid cysts. Br J Surg. 101(6):669-75, 2014 Benhamiche H et al: Peritoneal hydatidosis and hepatic hydatid cyst perforation. Diagn Interv Imaging. 94(11):1157-60, 2013

613

Liver

Hepatic Hydatid Cyst

(Left) Axial CECT from a 67year-old male immigrant shows numerous typical hydatid "cysts" within the liver (and anterior abdominal wall ). It is unusual to see so many abscesses in a patient. (Right) Axial CECT from the same patient shows a complex cystic mass in the right kidney as well as the liver . Hydatid disease can affect any abdominal organ, though involvement of retroperitoneal organs is unusual.

(Left) Longitudinal sonogram shows a complex echogenic mass with enhanced transmission as evidence of fluid content. A curvilinear echogenic scolex and highly echogenic debris attest to the complex nature of the cyst contents. (Right) Axial CECT from a 78-year-old female Italian immigrant shows large complex masses within the liver . The largest cyst has peripheral wall calcification and numerous septa .

(Left) Coronal reformatted CT from the same patient shows the spherical morphology of the "mother" cyst and focal calcifications in the walls of the exocyst and "daughter" cysts . (Right) Coronal CT from the same patient shows contiguous exocysts in the liver. This woman came from a sheep-raising area of Italy where hydatid disease is endemic. In this setting, the CT findings are essentially diagnostic of hydatid cyst, and serology was confirmatory.

614

Hepatic Hydatid Cyst Liver

(Left) Coronal T2WI MR section shows a large, complex cystic mass . Note the presence of numerous septa within the mass, representing scolices or "daughter" cysts within the larger "mother" or exocyst. All cyst components are bright on T2WI. (Right) Coronal T1WI MR section in the same patient shows the same complex cystic mass . The "daughter" cysts are usually closer to water intensity on T1WI than the matrix within the "mother" cyst, as in this case.

(Left) Axial CECT of E. multilocularis shows a large, deeply infiltrative hepatic mass with multiple foci of calcification . The mass compresses or occludes the inferior vena cava, indicated by an enlarged azygous vein . (Right) The calcification in the mass in the same patient is amorphous, and the mass appears solid. E. multilocularis has imaging and clinical characteristics that resemble an invasive malignancy more than the more common form of echinococcal (E. granulosus), or hydatid, disease.

(Left) Axial CT from the same patient shows the widespread, infiltrative, tumor-like mass due to E. multilocularis. (Right) Axial CECT from the same patient shows encasement of the portal vein by the infiltrative, invasive infection by E. multilocularis.

615

Liver

Hepatic Schistosomiasis KEY FACTS

TERMINOLOGY • Hepatic parasitic infestation by Schistosoma species

IMAGING • CT: "Tortoise shell" or "turtle back" appearance ○ Periportal fibrotic bands and widened fissures ○ Capsular calcification (parallel or perpendicular to liver surface) • Portal hypertension in advanced disease ○ Splenomegaly and varices • US: Bull's-eye lesion: Represents anechoic portal vein surrounded by echogenic mantle of fibrous tissue ○ Hyperechoic and thickened walls of portal venules ○ Network of echogenic septa outlining polygonal areas of normal-appearing liver • US elastography demonstrates hepatic fibrosis • MR shows same morphologic signs as CT of liver damage and portal hypertension

(Left) Graphic shows striking periportal edema and fibrosis with widened fissures between hepatic segments. (Right) Axial CT shows signs of portal hypertension, including large varices and splenomegaly. Note the extraordinarily widened hepatic fissures deeply dividing the segments of the liver along the portal vein branches. This is a characteristic feature of hepatic schistosomiasis; the appearance of the liver has been described as that of a tortoise shell.

(Left) In low-power micropathology, portal tracts show chronic inflammation, luminal narrowing, and several granulomas containing degenerated Schistosoma ova . (Courtesy J. Misdraji, MD.) (Right) Axial NECT of the liver shows extensive calcification and peripheral fibrosis in patterns such as thin curvilinear , subcapsular band-like , and confluent . The predominantly peripheral location and calcification of the fibrotic regions are distinguishing features from viral or alcoholic cirrhosis.

616

○ MR elastography provides a measure of extent of hepatic fibrosis, which may determine therapy and prognosis

TOP DIFFERENTIAL DIAGNOSES • Hepatic cirrhosis ○ Often has widened fissures but not as much periportal fibrosis or calcification as with schistosomiasis

CLINICAL ISSUES • Most common cause of hepatic fibrosis in the world ○ Over 200,000,000 persons, mostly in tropics • Different Schistosoma species affect urinary tract more than liver • Oral praziquantel for treatment

DIAGNOSTIC CHECKLIST • Exclude other causes of hepatic fibrosis or cirrhosis • Hepatic mosaic "tortoise shell" pattern of fibrosis and calcification

Hepatic Schistosomiasis

DIFFERENTIAL DIAGNOSIS

Synonyms

Hepatic Cirrhosis

• Bilharzia, bilharziasis, blood fluke

• Hepatic schistosomiasis may cause or simulate cirrhosis from other causes • Cirrhosis often has widened fissures but not as much periportal edema and fibrosis as with schistosomiasis

Definitions • Hepatic parasitic infestation by Schistosoma species

IMAGING

PATHOLOGY

General Features

General Features

• Best diagnostic clue ○ Periportal fibrotic bands and widened fissures with calcification • Location ○ Diffuse throughout liver • Morphology ○ Distortion of liver architecture and surface contour by extension of periportal fibrosis

• Etiology ○ S. japonicum: North Asia ○ S. mansoni: Africa, Egypt, Caribbean, South America – Causes most severe disease in liver ○ S. hematobium: Mediterranean, Africa, Southeast Asia – Typically affects urinary tract

CT Findings

• Adult worms live in pairs within portal veins for years • Female worm releases eggs, which travel in blood to become trapped in tissues of different organs • Trapped eggs stimulate granulomatous reaction, which is reversible in early stages but becomes fibrotic later • Fibrosis may lead to organ damage

• CECT ○ Hepatic involvement – "Tortoise shell" or "turtle back" appearance □ Represents calcified septa, aligned along and perpendicular to liver capsule – Capsular calcification – Markedly dysmorphic liver with peripheral atrophy, caudate hypertrophy – Periportal edema, fibrosis, volume loss – Splenomegaly and varices ○ Colonic involvement – Ulceration of mucosa – Submucosal edema + fibrosis – May progress to calcification of colonic wall

MR Findings • Shows same morphologic signs as CT of liver damage and portal hypertension • MR elastography provides a measure of extent of hepatic fibrosis, which may determine therapy and prognosis

Ultrasonographic Findings • Grayscale ultrasound ○ Atrophic liver in late stage (fibrosis and portal hypertension) ○ Irregular/notched liver surface ○ Echogenic granulomata – Peripheral/subcapsular location ○ Periportal fibrosis – Bull's-eye lesion: Represents anechoic portal vein surrounded by echogenic mantle of fibrous tissue ○ Mosaic pattern – Network of echogenic septa outlining polygonal areas of normal-appearing liver – Represents complete septal fibrosis (inflammation and fibrosis as reaction to embolized eggs) ○ Elastography demonstrates hepatic fibrosis

Liver

TERMINOLOGY

Gross Pathologic & Surgical Features

Microscopic Features • Multiple tiny granulomas scattered in periphery of liver • Granuloma consists of egg in center surrounded by macrophages, lymphocytes, neutrophils, and eosinophils

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Many affected patients remain asymptomatic ○ Acute infection: Dermatitis, fever, hepatomegaly ○ Hepatic – Hepatomegaly + splenomegaly in acute infection – Chronic □ Portal hypertension and splenomegaly □ Hepatic function remains normal □ Ascites + bleeding varices are major causes of morbidity + mortality ○ Intestinal: Fatigue, abdominal pain, diarrhea, dysentery ○ Urinary: Dysuria, frequency, terminal hematuria ○ Pulmonary: Cough, wheeze, fatigue, dyspnea, hemoptysis – Usually follows hepatic infestation with Schistosoma eggs that embolize into lungs via portosystemic collaterals (varices)

Treatment • Oral praziquantel • Oral corticosteroids for symptomatic treatment of acute disease • Treat complications ○ e.g., sclerotherapy for esophageal varices

Imaging Recommendations • Best imaging tool ○ Ultrasound & CT or MR for diagnosis and follow-up 617

Liver

Hepatic Schistosomiasis

(Left) Axial NECT of a 66-yearold male immigrant from the Philippines with known metastatic sarcoma shows a complex right pleural effusion . Liver morphology is distorted with curvilinear bands of calcification in the parenchyma and subcapsular region. (Right) NECT in the same patient shows widened fissures and a small distorted liver. Note branching bands of calcification in parenchyma and capsule , typical for hepatic schistosomiasis. The mass in the right paraspinal muscle is the sarcoma.

(Left) Axial NECT in the same patient shows diffuse thickening of the wall of the transverse colon, with calcification of the mucosa or submucosa . (Right) Axial CT in the same patient shows massive thickening of the wall of the ascending colon with a densely calcified central "stripe" , proven to represent acute and chronic granulomatous colitis due to schistosomiasis. The mass in the right psoas is the sarcoma, presumably unrelated.

(Left) Axial NECT in the same patient shows calcification within the wall of the descending and sigmoid colon due to schistosomal granulomatous colitis. (Right) Coronal reformation of the NECT in the same patient shows the distorted liver with volume loss, widened fissures, and bands of calcified fibrosis . Also evident are the intramural calcifications of the colonic wall due to chronic granulomatous colitis and the massive thickening of the ascending colon due to acute colitis.

618

Hepatic Schistosomiasis Liver

(Left) Grayscale transabdominal ultrasound of a 20-year-old woman with hepatic schistosomiasis shows innumerable tiny, echogenic nodules within a small, scarred liver, along with discontinuous bands of echogenic fibrosis . The echogenic foci likely represent granulomas. (Right) A sagittal US image in the same patient shows the small, echogenic, fibrotic liver with discontinuous linear echogenic bands of fibrosis .

(Left) Sagittal grayscale transabdominal sonography of a 42-year-old man with hepatic schistosomiasis shows echogenic fibrotic septa extending peripherally from the porta hepatis. (Right) Sagittal US image in the same patient shows more of the characteristic bands of periportal fibrosis .

(Left) A transverse sonogram of a 21-year-old man with hepatic schistosomiasis shows bands of fibrosis surrounding portal tracts. (Right) An additional transverse US image in the same patient shows more of the extensive, periportal, echogenic bands of fibrosis .

619

Liver

Viral Hepatitis KEY FACTS

TERMINOLOGY • Acute hepatitis: Hepatocyte necrosis and inflammation resulting from acute viral infection

IMAGING • In medical practice, hepatitis usually refers to viral infection ○ Hepatitis B and C are major variants ○ Only hepatitis B and hepatitis C cause chronic disease ○ Hepatitis C is leading cause of cirrhosis and hepatocellular carcinoma in USA • Role of imaging in cases of viral hepatitis ○ Try to exclude biliary obstruction or neoplasm ○ Evaluate parenchymal damage noninvasively • Acute hepatitis imaging: Hepatomegaly, periportal edema, gallbladder wall thickening • Chronic active hepatitis: Lymphadenopathy in most • Cirrhosis: Nodular, shrunken liver, portal hypertension (ascites, varices, splenomegaly)

(Left) H&E demonstrates lymphocytes passing beyond the limiting plate and surrounding hepatocytes. Mild hepatocyte swelling and necrosis are often evident, reflecting the resultant hepatocyte injury. (Courtesy L. Yerian, MD.) (Right) Longitudinal ultrasound in a patient with acute viral hepatitis shows a markedly thickened gallbladder wall , but no calculi. Acute hepatitis generally causes more impressive gallbladder wall edema than does acute cholecystitis.

(Left) Axial CECT in the same patient with acute viral hepatitis shows hepatomegaly, periportal edema , and porta hepatis lymphadenopathy . (Right) Axial CECT in the same patient shows massive gallbladder wall thickening and a small amount of ascites . There is nothing specific about these findings to indicate the exact etiology of this case of hepatitis. Imaging helps to exclude other causes of acute abdominal pain and liver disfunction, such as biliary obstruction.

620

○ Chronic hepatitis B can cause hepatocellular carcinoma without cirrhosis • Multiphasic CECT &/or MR is mandatory for hepatocellular carcinoma surveillance among cirrhotic patients

TOP DIFFERENTIAL DIAGNOSES • • • •

Steatosis, steatohepatitis Hepatitis, autoimmune Hepatic injury from toxins Passive hepatic congestion

CLINICAL ISSUES • New combination of protease inhibitor (simeprevir) and nucleotide polymerase inhibitor (sofosbuvir) holds real promise for cure of many patients with hepatitis C virus

DIAGNOSTIC CHECKLIST • Multiphasic MR with elastography is best single test for evaluation of patients with chronic hepatitis and cirrhosis

Viral Hepatitis

Abbreviations • Hepatitis B virus (HBV) • Hepatitis C virus (HCV) • Epstein-Barr virus (EBV)

Definitions • Acute hepatitis: Hepatocyte necrosis and inflammation resulting from acute viral infection

IMAGING General Features • Best diagnostic clue ○ Acute hepatitis: Hepatomegaly, periportal and gallbladder wall edema in acutely ill patient • Size ○ Acute: Enlarged, homogeneous liver ○ Chronic: Small, heterogeneous, nodular liver • Morphology ○ Micronodular cirrhosis • Other general features ○ In medical practice, hepatitis usually refers to viral infection – Hepatitis B and C are major variants ○ Role of imaging in cases of viral hepatitis – Try to exclude biliary obstruction or neoplasm – Evaluate parenchymal damage noninvasively

CT Findings • CECT ○ Acute viral hepatitis – Hepatomegaly, gallbladder wall thickening – Periportal hypodensity (fluid, lymphedema) – Acute viral hepatitis rarely causes diffuse hypoattenuation of liver □ Unlike acute alcoholic or nonalcoholic steatohepatitis – Fulminant hepatic failure □ Focal or global volume loss of liver, diffuse hepatocellular necrosis (low density) + ascites on imaging □ Can develop acutely, subacutely, or in setting of cirrhosis □ Often manifested by hepatic encephalopathy □ Usually due to coexisting hepatic injury (e.g., alcohol, other viral infection) or following variceal hemorrhage or sepsis in patient with cirrhosis ○ Chronic active hepatitis – Lymphadenopathy in porta hepatis, gastrohepatic ligament, and retroperitoneum (in 65% of cases) – Hyperdense, small regenerating nodules within liver (better seen on NECT than CECT) □ Regenerating nodules may be isodense with liver on CECT ○ Cirrhosis – Volume loss, especially in medial and anterior segments of liver – Signs of portal hypertension □ Splenomegaly, ascites, varices

– Increased risk of hepatocellular carcinoma (HCC)

Liver

TERMINOLOGY

MR Findings • Viral hepatitis ○ Increase in T1 and T2 relaxation times of liver ○ T2WI: High signal intensity bands paralleling portal vessels (periportal edema and fibrosis) ○ MR elastography provides noninvasive measure of extent of liver fibrosis – Correlates well with progression of disease or response to treatment

Ultrasonographic Findings • Grayscale ultrasound ○ Acute viral hepatitis – in liver and spleen size, echogenicity of liver – "Starry sky" appearance: Increased echogenicity of portal venous walls – Periportal hypo-/anechoic area (hydropic swelling of hepatocytes) – Thickening of gallbladder wall ○ Chronic viral hepatitis, cirrhosis – Increased echogenicity of liver and coarsening of parenchymal texture

Imaging Recommendations • Best imaging tool ○ US usually sufficient to suggest diagnosis of acute viral hepatitis – Diagnosis is established by clinical exam, serology ± liver biopsy ○ US may be sufficient for imaging surveillance of patients with hepatitis C – Prior to development of heterogeneous, nodular, fibrotic, cirrhotic liver – US has poor sensitivity and specificity for detection of HCC in cirrhotic liver □ Multiphasic CECT &/or MR is mandatory for HCC surveillance among cirrhotic patients • Protocol advice ○ Multiphasic (arterial, venous, delayed phase) CT or MR for cirrhotic patients or those with chronic hepatitis B ○ US or MR elastography to assess extent of liver fibrosis

DIFFERENTIAL DIAGNOSIS Steatosis, Steatohepatitis • Diffuse decreased attenuation of enlarged liver • T1WI out-of-phase GRE: Selective signal dropout from areas of steatosis

Hepatitis, Autoimmune • May occur with other autoimmune diseases • Band-like and confluent fibrosis are common

Hepatic Injury From Toxins • Indistinguishable from viral hepatitis by imaging

Passive Hepatic Congestion • Early enhancement of dilated inferior vena cava and hepatic veins on arterial phase CT or MR • Doppler: Loss of triphasic pattern in dilated IVC/hepatic veins 621

Liver

Viral Hepatitis

Diffuse Lymphoma • Hepatomegaly due to diffuse infiltration by tumor • More common in immunosuppressed patients

PATHOLOGY General Features • Etiology ○ Viral hepatitis: Caused by 1 of several viral agents – Hepatitis A, B, C, D, E, and Epstein-Barr viruses – Only hepatitis B and C cause chronic hepatic injury □ Unless liver is injured by other viruses or toxins (e.g., combination of alcohol and viral hepatitis) – Some patients have combined HBV and HCV (similar modes of transmission) □ Probably results in more severe disease than single form of hepatitis ○ Hepatitis A – Usually spread by oral or fecal-oral route – Common cause of community outbreaks related to contaminated food or water – Accounts for ~ 1/2 of acute viral hepatitis cases in USA ○ Hepatitis B – Parenteral, perinatal, and sexual transmission – Accounts for ~ 40% of acute hepatitis in US □ 400,000,000 people worldwide are chronically infected with HBV – ~ 10% of infected patients develop chronic infection – HBV viral genome can act as oncogene □ Cirrhosis is not a prerequisite for HCC – Rarely recurs after transplantation since advent of antiviral prophylaxis ○ Hepatitis C – Parenteral, perinatal, and sexual transmission □ Mostly by intravenous route □ Sexual + perinatal transmission is less common – Accounts for ~ 20% of acute viral hepatitis cases in USA □ Only 10-15% of infected individuals develop symptomatic acute hepatitis – ~ 85% of infected patients develop chronic infection □ Progression is slow (over decades) – Hepatitis C is currently the leading cause of cirrhosis in USA □ In patients with chronic HCV, 1-2% per year develop HCC – HCV may recur after transplantation ○ Epstein-Barr virus – Spread by intimate contact with saliva – Cause of "infectious mononucleosis" □ Liver involvement = EBV or "mono" hepatitis □ Usually resolves in 1-2 months

Gross Pathologic & Surgical Features • Acute viral hepatitis: Enlarged liver and tense capsule • Chronic fulminant hepatitis: Atrophic liver with ascites

Microscopic Features • Acute viral hepatitis ○ Lobular disarray – Diffuse, mixed lobular inflammatory cell infiltrates 622

○ Hepatocyte swelling ± necrosis • Chronic hepatitis B and C ○ Portal inflammation ○ Interface hepatitis (piecemeal necrosis) ○ Fibrosis – Periportal bridging (= cirrhosis)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute hepatitis – Malaise, anorexia, fever, pain, hepatomegaly, jaundice – Nausea, vomiting – Rarely, acute hepatic failure • Laboratory tests ○ Serum transaminases 5-10x normal values ○ Hepatitis viral surface antibodies and antigens in serum

Treatment • Acute viral hepatitis: Prophylaxis-IG, HBIG, vaccine; antiviral medication (e.g., ribavirin) • New combination of protease inhibitor (simeprevir) and nucleotide polymerase inhibitor (sofosbuvir) holds real promise for cure of many patients with HCV • Chronic viral hepatitis: Interferon for HBV and HCV

DIAGNOSTIC CHECKLIST Consider • Liver biopsy for diagnosis and staging

Image Interpretation Pearls • 3 most consistent findings in acute hepatitis: Hepatomegaly, periportal edema, gallbladder wall edema

SELECTED REFERENCES 1. 2. 3.

4. 5.

6.

7.

8.

9.

Chronic viral hepatitis. Treatment progress, hopes for cures. Mayo Clin Health Lett. 32(3):4-5, 2014 Ferraioli G et al: Shear wave elastography for evaluation of liver fibrosis. J Ultrasound Med. 33(2):197-203, 2014 Lee JE et al: Noninvasive assessment of hepatic fibrosis in patients with chronic hepatitis B viral infection using magnetic resonance elastography. Korean J Radiol. 15(2):210-7, 2014 Muir AJ: The rapid evolution of treatment strategies for hepatitis C. Am J Gastroenterol. 109(5):628-35; quiz 636, 2014 Runge JH et al: Comparison of interobserver agreement of magnetic resonance elastography with histopathological staging of liver fibrosis. Abdom Imaging. 39(2):283-90, 2014 Casado JL et al: Regression of liver fibrosis is progressive after sustained virological response to HCV therapy in patients with hepatitis C and HIV coinfection. J Viral Hepat. 20(12):829-37, 2013 van Meer S et al: Surveillance for hepatocellular carcinoma in chronic liver disease: evidence and controversies. World J Gastroenterol. 19(40):6744-56, 2013 Machado MV et al: Hepatic steatosis in hepatitis B virus infected patients: meta-analysis of risk factors and comparison with hepatitis C infected patients. J Gastroenterol Hepatol. 26(9):1361-7, 2011 Shao YY et al: Impact of baseline hepatitis B viral DNA levels on survival of patients with advanced hepatocellular carcinoma. Anticancer Res. 31(11):4007-11, 2011

Viral Hepatitis Liver

(Left) Axial CECT of a 24-yearold man with acute fulminant hepatic necrosis shows a markedly heterogeneous liver with evidence of volume loss (capsular retraction with low density due to massive hepatocellular necrosis). Note a large amount of ascites and pleural effusions. (Right) Another image from the same patient shows other large focal sites of liver necrosis . Patients with these findings plus clinical evidence of hepatic failure are likely to die unless urgent liver transplantation is performed.

(Left) Axial CECT of a 57-yearold man with chronic active viral hepatitis shows a liver of normal size and attenuation. Periportal edema is evident as a collar of lucency around intrahepatic portal venous branches. (Right) Axial CT of the same patient shows enlarged portocaval and porta hepatis lymph nodes . Lymphadenopathy is seen in at least 2/3 of patients with viral hepatitis and should not be interpreted as a sign of malignancy.

(Left) Axial CT of the same patient with chronic viral hepatitis with acute exacerbation shows edema of the gallbladder wall . (Right) H&E-stained specimen demonstrates a focus of necroinflammatory activity in chronic hepatitis C. There is a collection of inflammatory cells and a single acidophil body (a.k.a., a councilman body or necrotic hepatocyte). (Courtesy L. Yerian, MD.)

623

Liver

Viral Hepatitis

(Left) Axial CECT of a 40-yearold woman with acute onset of fever, malaise, and jaundice due to viral hepatitis shows periportal edema as a collar of low density surrounding the vessels. (Right) Axial CT of the same patient shows striking thickening of the gallbladder wall with the lumen almost completely collapsed. A small amount of ascites is noted .

(Left) Sagittal US of the same patient with acute viral hepatitis shows that the liver is relatively sonolucent with accentuation of the echogenicity of the perivascular spaces. (Right) Sagittal US of the gallbladder (calipers) in the same patient shows striking wall thickening with the lumen almost completely collapsed. The CT and US findings are compatible with those of acute hepatitis, but the diagnosis is based on clinical and serologic findings, often supplemented with a liver biopsy.

(Left) Axial CECT in a patient with chronic active viral hepatitis shows an enlarged cardiophrenic lymph node . (Right) Additional lymphadenopathy is seen in the porta hepatis . The hepatic fissures are widened, suggesting that the disease has progressed to cirrhosis, which was confirmed on liver biopsy.

624

Viral Hepatitis Liver

(Left) This 66-year-old man was recently discovered to have a chronic hepatitis B infection without apparent clinical, laboratory, or imaging signs of cirrhosis. Axial T2WI MR shows 2 very bright small cysts and a moderately bright spherical mass that proved to be HCC. (Right) Axial T1WI MR of the same patient shows an encapsulated hypointense mass , representing hepatocellular carcinoma (HCC).

(Left) Arterial phase contrastenhanced T1WI MR of the same patient shows heterogeneous hypervascularity within the HCC . (Right) Venous phase T1WI MR of the same patient shows contrast washout from the HCC, along with better definition of the capsule . In patients with chronic hepatitis B infection, HCC can develop before or without clinical, imaging, or even biopsy evidence of cirrhosis.

(Left) Coronal reformatted CECT of an 18-year-old man with acute upper abdominal pain, fever, and malaise due to mononucleosis caused by Epstein-Barr virus (EBV) shows massive hepatosplenomegaly and edema of the gallbladder wall . This represents EBV or "mono" hepatitis. (Right) Axial CT of the same patient shows pelvic ascites .

625

Liver

Alcoholic Liver Disease KEY FACTS

TERMINOLOGY • Hepatocyte injury and inflammation resulting from chronic alcohol consumption

IMAGING • Alcoholic steatohepatitis (diffuse fatty infiltration) ○ Diffuse hypodensity (on CT) in liver (due to fatty infiltration) ○ T1WI out-of-phase GRE: Decreased signal intensity of liver (due to lipid in liver) ○ Indistinguishable from liver fibrosis/cirrhosis on US • Acute fulminant hepatitis ○ Volume loss of liver, ascites, high mortality • Chronic alcoholic hepatitis ○ Mixture of steatosis and early cirrhotic changes ○ Widened fissures, caudate:right lobe ratio • Cirrhosis due to alcoholic liver disease (ALD) ○ Indistinguishable by imaging from cirrhosis resulting from chronic viral hepatitis

(Left) H&E photomicrograph shows macrovesicular steatosis , a typical finding in alcoholic cirrhosis. (Courtesy M. Yeh, MD, PhD.) (Right) H&E photomicrograph shows ballooned hepatocytes containing many Mallory-Denk bodies, along with lobular inflammation featuring satellitosis of neutrophils around the ballooned cells. These are typical features of alcoholic steatohepatitis. (Courtesy M. Yeh, MD, PhD.)

(Left) This 36-year-old man with acute abdominal pain and abnormal liver functions was 1st evaluated with US, which showed an enlarged, diffusely echogenic liver. Note the increased echogenicity of the liver relative to the kidney and the poor penetration of sound waves, with poor definition of the right hemidiaphragm . (Right) Axial CECT in the same patient confirms hepatomegaly and steatosis, with the liver being substantially lower in attenuation than the spleen on this venous phase CECT.

626

○ Small nodular liver with signs of portal hypertension (ascites, splenomegaly, varices) • Protocol advice ○ Once cirrhosis has developed, sonography is of less value in surveillance than CT or MR ○ Need multiphasic, contrast-enhanced CT or MR

TOP DIFFERENTIAL DIAGNOSES • Viral hepatitis ○ Usually does not cause image-detectable steatosis • Nonalcoholic steatosis or steatohepatitis ○ Pathology and imaging: Findings nearly identical to alcoholic steatosis • Hepatitis, autoimmune

CLINICAL ISSUES • ALD is clinical spectrum from asymptomatic to chronic progressive to acute hepatic failure

Alcoholic Liver Disease

DIFFERENTIAL DIAGNOSIS

Abbreviations

Viral Hepatitis

• Alcoholic liver disease (ALD)

• Does not usually cause image-detectable steatosis

Definitions

Nonalcoholic Steatosis or Steatohepatitis

• Hepatocyte injury and inflammation resulting from chronic alcohol consumption

• Pathology and imaging: Findings nearly identical to alcoholic steatosis

IMAGING General Features • Best diagnostic clue ○ Combination of steatosis and cirrhotic morphology on imaging

CT Findings • CECT ○ Acute alcoholic hepatitis – Hepatomegaly – Diffuse hypodense liver (due to fatty infiltration) □ Fatty infiltration may be focal, lobar, or segmental ○ Acute fulminant hepatitis – Volume loss of liver, ascites, high mortality ○ Chronic alcoholic hepatitis – Mixture of steatosis and early cirrhotic changes – Steatosis: Decreased density of liver □ Normal liver attenuation > spleen on NECT ○ Cirrhosis due to ALD – Indistinguishable by imaging from cirrhosis resulting from chronic viral hepatitis – Nodular, shrunken liver – Increased caudate:right lobe ratio □ Often > 1.0 (normal caudate is < 60% width of right lobe) – Signs of portal hypertension □ Splenomegaly, ascites, varices

MR Findings • Alcoholic steatohepatitis (diffuse fatty infiltration) ○ T1WI in-phase GRE: Signal intensity of liver is higher than spleen or muscle ○ T1WI out-of-phase GRE: Decreased signal intensity of liver (due to lipid in liver)

Autoimmune Hepatitis • May be indistinguishable from ALD by imaging

PATHOLOGY General Features • Etiology ○ Alcohol is a direct hepatotoxin

Gross Pathologic & Surgical Features • Alcoholic steatohepatitis: Enlarged, yellow, greasy liver • Cirrhosis: Small, shrunken, nodular liver

Microscopic Features • Combination of hepatocyte injury, inflammation, steatosis, and fibrosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute alcoholic hepatitis – Anorexia, nausea, vomiting, fever, pain, hepatomegaly, jaundice – Some patients are asymptomatic ○ End-stage patients have encephalopathy, ascites, coagulopathy, varices • Moderately elevated serum transaminases ○ AST:ALT ratio > 2 • Hypoalbuminemia, prolonged PTT, INR in advanced disease

Demographics • Epidemiology ○ Alcohol accounts for ~ 20% of cirrhosis cases in USA – Prevalence of ALD is decreasing relative to in viral hepatitis and nonalcoholic steatohepatitis (NASH)

Ultrasonographic Findings

Natural History & Prognosis

• Grayscale ultrasound ○ Alcoholic steatohepatitis – Liver parenchyma: echogenicity and sound attenuation – Indistinguishable from liver fibrosis/cirrhosis

• Prognosis ○ Quite variable course of disease – May cause fulminant hepatic failure and death – May exist as subclinical disease until cirrhosis develops – With continued alcoholism, likely to progress to cirrhosis – Common cause of HCC

Imaging Recommendations • Best imaging tool ○ MR (in- and out-of-phase GRE images) for steatohepatitis • Protocol advice ○ Once cirrhosis has developed, sonography is of less value in surveillance – Need multiphasic, contrast-enhanced CT or MR to detect hepatocellular carcinoma (HCC)

Liver

TERMINOLOGY

SELECTED REFERENCES 1.

2.

Liangpunsakul S et al: The alcoholic hepatitis histologic score: structured prognostic biopsy evaluation comes to alcoholic hepatitis. Gastroenterology. 146(5):1156-8, 2014 Stickel F et al: Genetic determinants of alcoholic liver disease. Gut. 61(1):1509, 2012

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Liver

Alcoholic Liver Disease

(Left) Axial CECT in a patient with acute fulminant alcoholic and viral hepatitis shows a markedly heterogeneous liver with volume loss . Ascites and pleural effusions are also noted. Patients with such severe acute liver damage usually have a fatal outcome unless emergency liver transplantation is performed. (Right) Axial CECT in the same patient shows additional sites of heterogeneity and volume loss . In this setting, the hypodense areas are more likely due to hepatocellular necrosis than steatosis or fibrosis.

(Left) Axial NECT in a 40-yearold man with chronic alcohol abuse shows patchy low attenuation throughout the liver (compared with the spleen); this is indicative of steatosis (fatty liver) and likely indicates ongoing alcohol abuse. (Right) Axial CECT in the same patient shows a nodular hepatic surface, volume loss of the anterior and medial segments, and signs of portal hypertension (including varices and splenomegaly ).

(Left) Axial CECT in the same patient shows a nodular hepatic surface, volume loss of the anterior and medial segments , and signs of portal hypertension including varices , splenomegaly, and a small amount of ascites . (Right) Coronal reformatted CT in the same patient highlights the heterogeneity and nodularity of the liver and shows gallstones ,a common occurrence in cirrhosis.

628

Alcoholic Liver Disease Liver

(Left) This explant specimen from a patient with end-stage alcohol-induced cirrhosis shows a nodular cut surface and broad areas of confluent fibrosis . (Courtesy M. Yeh, MD, PhD.) (Right) Dense collagen fibers surround the terminal hepatic venules and hepatocytes in this specimen of cirrhosis due to alcoholic liver disease. (Courtesy M. Yeh, MD, PhD.)

(Left) Axial CECT in a 48-yearold man with chronic alcoholism shows a small liver with typical cirrhotic morphology, including wide fissures, a deep gallbladder fossa, and a "notch" on the undersurface of the liver . Porta hepatic lymphadenopathy is noted. There are huge perisplenic varices and a very small but patent portal vein . (Right) Axial CECT in the same patient shows varices and a spontaneous splenorenal shunt, resulting in marked enlargement of the left renal vein .

(Left) Coronal CT in the same patient shows the splenorenal shunt and the cirrhotic liver with a notched inferior surface . (Right) Coronal CT in the same patient shows the small portal vein and the huge varices . Portal vein size has no correlation with the degree of cirrhosis or portal hypertension.

629

Liver

Autoimmune Hepatitis KEY FACTS

TERMINOLOGY

• Alcoholic hepatitis

• Chronic hepatitis of unknown etiology characterized by hyperglobulinemia, circulating autoantibodies, and inflammatory changes on hepatic histology

CLINICAL ISSUES

IMAGING • Autoimmune hepatitis (AIH) is not diagnosed specifically by imaging criteria • Dysmorphic liver with prominent periportal fibrosis ± signs of portal hypertension ± irregular intrahepatic ductal dilation • MRCP is best for detecting irregular dilation of intrahepatic ducts in autoimmune-hepatitis primary sclerosing cholangitis (AIH-PSC) overlap disease

TOP DIFFERENTIAL DIAGNOSES • Primary biliary cirrhosis (PBC) • Primary sclerosing cholangitis (PSC) • Viral hepatitis

(Left) Venous phase CT shows heterogeneous liver parenchyma with evidence of periportal edema , a nonspecific sign often seen in acute hepatitis, among other causes. (Right) CT section in the same case shows subcapsular and peripheral wedge-shaped foci of hyperdensity , representing confluent fibrosis and is usually seen in advanced and more chronic liver damage. Liver biopsy showed acute and advanced liver injury due to autoimmune hepatitis (AIH).

(Left) Axial CECT of an autoimmune hepatitis-primary sclerosing cholangitis (AIHPSC) overlap shows a nodular, cirrhotic liver with signs of portal hypertension, including splenomegaly, ascites, and varices . The intrahepatic ducts are dilated with an abnormal arborization, suggestive of PSC. (Right) Axial CECT in the same patient shows dysmorphic liver, ascites, varices, and dilated, irregular intrahepatic bile ducts typical of primary sclerosing cholangitis.

630

• Diagnosis is based on exclusion of other forms of liver disease • Exclusion of viral, alcoholic, or toxic hepatic injury • ~ 20% of patients have overlap syndrome with other autoimmune diseases, especially PBC and PSC • May have many other autoimmune diseases, including lupus, rheumatoid arthritis, ulcerative colitis, polyglandular autoimmune disease, etc.

DIAGNOSTIC CHECKLIST • Role of imaging is to detect signs of acute or chronic liver injury, portal hypertension, associated abnormalities (e.g., biliary ductal disease)

Autoimmune Hepatitis

Abbreviations • Autoimmune hepatitis (AIH)

Synonyms • Chronic active hepatitis

Definitions • Chronic hepatitis of unknown etiology characterized by hyperglobulinemia, circulating autoantibodies, and inflammatory changes on hepatic histology

IMAGING General Features • Best diagnostic clue ○ Dysmorphic liver with prominent periportal fibrosis ± signs of portal hypertension ± irregular intrahepatic ductal dilation – Widened fissures, deep gallbladder fossa, caudate:right lobe ratio

Radiographic Findings • AIH is not diagnosed specifically by imaging criteria

CT Findings • CECT ○ Typical signs of cirrhosis + portal hypertension ○ Bands of fibrosis may show persistent, increased, delayed enhancement ○ Irregular dilation of intrahepatic ducts in autoimmune hepatitis-primary sclerosing cholangitis (AIH-PSC) overlap disease

MR Findings • Signs of cirrhosis ± portal hypertension • MRCP is best for detecting irregular dilation of intrahepatic ducts in AIH-PSC overlap disease

Imaging Recommendations • Best imaging tool ○ MR with MRCP

DIFFERENTIAL DIAGNOSIS Primary Biliary Cirrhosis (PBC) • Imaging and other features may simulate or coexist with AIH: AIH-PBC overlap disease • PBC typically affects middle-aged women • Leads to early cholestatic injury (pruritus + jaundice) • Imaging: Prominent regenerative nodules, lace-like fibrosis, large perihepatic lymph nodes

Primary Sclerosing Cholangitis (PSC) • Imaging and clinical features may simulate or coexist with AIH: AIH-PBC overlap disease • Often associated with ulcerative colitis • Irregular dilation and arborization of bile ducts with thickened walls

• Differentiation relies on serologic testing and evidence of viral antigens ± antibodies

Liver

TERMINOLOGY

Alcoholic Hepatitis • Imaging evidence of steatosis • History of alcohol use, biopsy evidence of steatosis, hepatocyte inflammation, and necrosis

PATHOLOGY Staging, Grading, & Classification • May exist as classic or typical form (type 1 AIH) ○ Accounts for ~ 80% of AIH cases in USA ○ Lab tests – serum alanine aminotransferase (> 5x upper limit of normal) – Immunoglobulin G (IgG) > 2x normal – + anti smooth muscle antibodies – + antinuclear antibodies (ANA) • "Overlap" or "variant" syndromes ○ Clinical and serologic features of other autoimmune diseases (20% of all patients with AIH) – PBC – PSC – Autoimmune cholangitis

CLINICAL ISSUES Demographics • Age ○ Occurs in children and adults of all ages – Onset usually occurs by age 40 years – Patients with later presentation often have evidence of chronic liver injury □ 25% have cirrhosis at time of initial diagnosis • Gender ○ Predominantly affects women (~ 70%)

Natural History & Prognosis • Most patients respond to immunosuppressive therapy ○ Others progress to chronic injury with cirrhosis

Treatment • Azathioprine, prednisone • Sympathomimetic amines (e.g., dextroamphetamine sulfate)

DIAGNOSTIC CHECKLIST Consider • Role of imaging is to detect signs of acute or chronic liver injury, portal hypertension, associated abnormalities (e.g., biliary ductal disease)

SELECTED REFERENCES 1.

2.

Weidner J et al: Marked improvement of the autoimmune syndrome associated with autoimmune hepatitis by treatment with sympathomimetic amines. Clin Exp Obstet Gynecol. 41(4):460-1, 2014 Sahni VA et al: Autoimmune hepatitis: CT and MR imaging features with histopathological correlation. Abdom Imaging. 35(1):75-84, 2010

Viral Hepatitis • Imaging and clinical features may be identical to AIH

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Liver

Steatosis and Steatohepatitis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Steatosis is metabolic complication of a variety of toxic, ischemic, and infectious insults to liver • Characterized by accumulation of increasing amounts of triglycerides within hepatocytes

• Lymphoma or metastases ○ Diffuse or multifocal lesions can be seen with steatosis or tumor • Hepatitis ○ Viral or other toxic etiologies • Opportunistic infection, hepatic

IMAGING • Diffuse (more common) or focal fatty infiltration ○ Often lobar, segmental, or wedge shaped ○ Along hepatic vessels, ligaments, and fissures ○ Presence of normal vessels coursing through "lesion" (fatty infiltration) • NECT: Liver attenuation < spleen • US: echogenicity, attenuation of sound beam • Best imaging clue ○ Decreased signal intensity of liver on T1 opposed-phase GRE images • Nonalcoholic steatohepatitis (NASH) looks similar to simple steatosis and alcoholic steatohepatitis

(Left) Cut section of an explanted liver shows a yellowish, greasy, pale appearance due to steatosis. Steatohepatitis can lead to progressive and irreversible liver failure. (Right) Axial NECT in the same patient shows diffuse low attenuation of the liver relative to the spleen and muscle. Note the area of fatty sparing around the gallbladder fossa . The liver also shows signs of cirrhosis, with widened fissures and a prominent caudate lobe.

(Left) T1WI GRE in-phase MR of diffuse steatosis shows no apparent hepatic abnormality. Note the small right adrenal nodule . (Right) T1WI GRE opposed-phase MR in the same patient shows selective dropout of signal from the liver, indicating the presence of excess lipid within the liver and also within an adrenal adenoma . The most specific imaging test to detect hepatic steatosis is MR, especially GRE in- and opposed-phase images.

632

PATHOLOGY • Focal steatosis or sparing: Most commonly due to variations in hepatic venous drainage

CLINICAL ISSUES • Most common cause of chronic liver disease in Western countries ○ Increasing in prevalence with epidemic of obesity and metabolic syndrome • NASH will likely become leading cause of cirrhosis and hepatocellular carcinoma in Western countries

Steatosis and Steatohepatitis

Synonyms • Hepatic steatosis or hepatic fatty metamorphosis • Nonalcoholic steatohepatitis (NASH)

Definitions • Characterized by accumulation of increasing amounts of triglycerides within hepatocytes • Steatosis is a metabolic complication of a variety of toxic, ischemic, and infectious insults to liver

IMAGING General Features • Best diagnostic clue ○ Decreased signal intensity of liver on T1WI opposedphase GRE images • Location ○ Focal, multifocal, or diffuse • Key concepts ○ Diffuse (more common) or focal fatty infiltration ○ Often lobar, segmental, or wedge shaped – More common along hepatic vessels, ligaments, and fissures ○ Rarely, unifocal or multifocal spherical lesions, simulating metastases or primary tumor ○ Fatty replacement occurs where glycogen is depleted from liver ○ Key on all imaging modalities – Presence of normal vessels coursing through "lesion" (fatty infiltration) ○ Variable imaging features of fatty liver based on – Amount of fat deposited in liver – Fat distribution within liver – Presence of associated hepatic disease □ e.g., porta hepatic lymphadenopathy and lymphedema in viral hepatitis □ In general, imaging cannot determine etiology of steatosis □ Nonalcoholic steatohepatitis (NASH) looks similar to simple steatosis and alcoholic steatohepatitis

CT Findings • NECT ○ Diffuse or focal – Decreased attenuation of liver compared to spleen □ Hepatic attenuation is inversely proportional to degree of steatosis – Normal: Liver 8-10 HU more than spleen on NECT □ High sensitivity (88-95%) and specificity (90-99%) □ In severe steatosis (> 30%), attenuation of hepatic vessels may be that of liver – Normal liver attenuation: 50-65 HU □ Attenuation < 48 HU = steatosis – Hepatic attenuation index: Calculation of ratio of hepatic to splenic attenuation □ < 0.8 = severe (> 30%) steatosis ○ Focal fatty infiltration: Low attenuation – Common location: Adjacent to falciform ligament – Due to nutritional ischemia at vascular watershed

○ Lobar, segmental, or wedge-shaped fatty infiltration – May have straight-line margin – Extending to liver capsule, usually without mass effect – Often greater in right than left lobe □ Reflects greater portal venous flow to right lobe • CECT ○ Attenuation measurements and comparisons are less reliable than for NECT – Dependent on timing relative to contrast administration □ Accuracy only ~ 75-80% for mild to moderate steatosis – Due to earlier enhancement of spleen (lack of portal blood supply) □ Arterial phase imaging is very unreliable – On venous phase or delayed CECT, steatotic liver is usually > 35 HU less dense than spleen ○ Normal vessels course through "lesion" (fatty infiltration) ○ Dual-energy CT – Scan at different tube currents (e.g., 80 + 140 kVp) – Steatosis will be accentuated on lower kVp sequence

Liver

TERMINOLOGY

MR Findings • T1WI in-phase gradient echo (chemical shift) ○ Increased signal intensity of fatty liver > spleen ○ On 1.5 Tesla (T) TEs of ~ 4.6 (in phase) and 2.3 msec (opposed phase) ○ On 3 T magnets, shorter TEs can be used – Can detect + quantitate steatosis better than on 1.5 T MR or CT • T1WI out-of-phase gradient echo ○ Loss of signal intensity from foci of steatosis ○ Signal is lost from voxels that contain both fat and water • T1 C+ out-of-phase GRE image ○ Paradoxical decreased signal intensity of liver • Short T1 inversion recovery (STIR) ○ Shows fatty areas as low signal intensity • MR spectroscopy (MRS) ○ Fatty liver demonstrates increase in intensity of lipid resonance peak ○ Used for quantitative assessment of fatty infiltration of liver • Multi-echo gradient echo MR ○ Emerging method for reliable quantification of hepatic fat content

Ultrasonographic Findings • Grayscale ultrasound ○ Diffuse fatty infiltration – Diffuse increased hepatic echogenicity – Increased attenuation of ultrasound beam – Normal liver echogenicity is slightly > that of kidney or spleen – Steatosis may obscure visualization of diaphragm and intrahepatic vessels – US grading of steatosis is subjective and prone to interobserver variation ○ Hepatic steatosis and fibrosis frequently coexist – Produce similar sonographic findings □ Limits value of US in quantification and surveillance of steatosis 633

Liver

Steatosis and Steatohepatitis ○ Poor visualization of portal and hepatic veins ○ Focal fatty infiltration – Hyperechoic nodule – Multiple confluent, hyperechoic lesions ○ Focal fatty sparing: Pseudotumor variations – "Target" lesion: Hypoechoic area with central hyperechoic core – Ovoid or spherical hypoechoic area in otherwise echogenic liver – Usually seen in segment 5 of fatty liver or along gallbladder fossa

Imaging Recommendations • Best imaging tool ○ NECT or T1WI in- and out-of-phase gradient echo images • Protocol advice ○ Be wary of diagnosing steatosis on CECT, especially arterial phase

DIFFERENTIAL DIAGNOSIS Lymphoma or Metastases • Diffuse lymphoma infiltration: Indistinguishable from normal liver or steatosis • Confluent tumor often distorts vessels and bile ducts • Multifocal lymphoma or mets are usually well-defined, lowdensity masses ○ Steatosis may have similar appearance ○ MR or PET allows confident diagnosis

Hepatitis • From viral or other toxic injury • Viral hepatitis usually does not change attenuation of liver unless there is massive hepatocellular necrosis (hepatic volume loss, ascites, etc.) • Associated gallbladder wall and periportal edema • Clinical presentation suggests diagnosis ○ Very ill patient with liver function tests (LFTs) (serum enzymes)

Opportunistic Infection, Hepatic • Diffuse infection (viral, mycobacterial, fungal, etc.) in immunocompromised patient • May cause diffuse low attenuation in liver • Acutely ill patient with abnormal LFTs requires liver biopsy for diagnosis

PATHOLOGY General Features • Etiology ○ Metabolic derangement – Diabetes (50%), obesity, and hyperlipidemia – Severe hepatitis and protein malnutrition – Parenteral hyperalimentation, malabsorption – Pregnancy, inflammatory bowel disease – Cystic fibrosis, Reye syndrome ○ Hepatotoxins – Alcohol (> 50%), carbon tetrachloride ○ Drugs – Tetracycline, amiodarone, corticosteroids, antiretroviral 634

– Salicylates, tamoxifen, calcium channel blockers • Associated abnormalities ○ NASH – Subset of nonalcoholic fatty liver disease □ Strong association with metabolic syndrome – Inflammatory component distinguishes this from simple steatosis – Seen in patients with hyperlipidemia and diabetes – May lead to cirrhosis, hepatocellular carcinoma • Fat deposited in liver due to ○ Ethanol; increased hepatic synthesis of fatty acids ○ Carbon tetrachloride and high-dose tetracycline; hepatic oxidation or utilization of fatty acids ○ Starvation, steroids, and alcohol – Impaired release of hepatic lipoproteins – Excessive mobilization of fatty acids from adipose tissue ○ Focal steatosis or sparing: Most commonly due to variations in hepatic venous drainage – Veins from gallbladder, stomach, etc., may drain directly into liver – Do not deliver chylomicrons from intestine foci of focal fatty sparing

Gross Pathologic & Surgical Features • Liver may weigh 4-6 kg • Soft, yellow, greasy cut surface

Microscopic Features • Depends on etiology and severity • Macrovesicular fatty liver (most common type) ○ Hepatocytes with large cytoplasmic fat vacuoles displacing nucleus peripherally – Examples: Alcohol and diabetes mellitus • Steatohepatitis ○ Ballooning degeneration of hepatocytes ○ Lymphocytic and neutrophilic inflammation ○ Sinusoidal fibrosis • Steatohepatitis with cirrhosis ○ Extensive fibrosis surrounding regenerative nodules ○ Decrease in number and extent of fat-laden hepatocytes

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Often asymptomatic, but often with abnormal LFTs ○ Enlarged liver in obese or diabetic patient ○ Alcoholic patients – 1/3 asymptomatic – 2/3 with acute injury: RUQ pain, tenderness, hepatomegaly • Clinical profile ○ Asymptomatic alcoholic, obese, or diabetic patient with enlarged liver, abnormal LFTs • Lab data ○ Asymptomatic fatty liver – Normal to mildly elevated LFTs ○ Alcoholic and nonalcoholic steatohepatitis – May have markedly abnormal LFTs • Diagnosis

Steatosis and Steatohepatitis

Demographics • Age ○ Childhood through adulthood • Epidemiology ○ Steatosis is most common cause of chronic liver disease in Western countries – Strongly associated with insulin resistance and hypertriglyceridemia ○ Seen in up to 50% of patients with diabetes mellitus, > 50% of alcoholics, 80-90% of obese patients – Nonalcoholic steatosis is now more prevalent alcoholic etiology in USA ○ Increasing in prevalence with epidemic of obesity and metabolic syndrome – 15-20% of obese patients have steatohepatitis (NASH) – NASH found in > 50% of patients undergoing bariatric surgery – NASH will likely become leading cause of cirrhosis and hepatocellular carcinoma (HCC) in Western countries ○ Seen in 25-35% of USA population – Diagnosis of steatosis in asymptomatic person may preclude him or her from being a partial-liver (living) donor – Presence of steatosis might increase morbidity and mortality for both donor and recipient ○ Chemotherapy-associated steatohepatitis (CASH) – May result from many different chemotherapeutic agents – Important cause of liver dysfunction in oncology patients – May limit therapeutic options □ e.g., may need to decrease or suspend chemotherapy □ May preclude resection of focal hepatic tumor due to decreased hepatic reserve caused by CASH

Natural History & Prognosis • Complications ○ Acute fatty liver – Alcoholic binge, pregnancy, carbon tetrachloride exposure – May present with jaundice, acute hepatic failure, and encephalopathy • Prognosis ○ Alcoholics: Gradual disappearance of fat from liver after 4-8 weeks of adequate diet and abstinence from alcohol ○ Resolves in 2 weeks after discontinuation of parenteral hyperalimentation ○ NASH may progress to chronic liver failure ○ Steatosis is synergistic with viral hepatitis more severe injury

Treatment

Liver

○ Biopsy and histology ○ Biopsy can have sampling error, complementary to imaging – Biopsy is necessary to distinguish simple steatosis from steatohepatitis – Imaging is noninvasive and more useful for initial detection and evaluation of response to therapy

• Removal of alcohol or offending toxins • Correction of metabolic disorders ○ Weight loss program; bariatric surgery • Lipotropic agents such as choline when indicated ○ Patient must avoid alcohol and control diabetes

DIAGNOSTIC CHECKLIST Consider • Rule out other liver pathologies that may mimic focal or diffuse steatosis (fatty liver)

Image Interpretation Pearls • Decreased attenuation of liver compared to spleen • Key on all imaging modalities is presence of normal vessels coursing through "lesion" (fatty infiltration)

SELECTED REFERENCES 1. 2. 3. 4. 5.

6. 7.

8.

9. 10.

11. 12.

13.

14.

15.

16.

17. 18.

Pais TP et al: Multiple liver lesions of unusual benign etiology mimicking metastatic disease. Gastroenterology. 147(2):e10-1, 2014 Zoppini G et al: Mortality from chronic liver diseases in diabetes. Am J Gastroenterol. 109(7):1020-5, 2014 Raptis DA et al: MRI: the new reference standard in quantifying hepatic steatosis? Gut. 61(1):117-27, 2012 Lazo M et al: Non-alcoholic fatty liver disease and mortality among US adults: prospective cohort study. BMJ. 343(7832):d6891, 2011 Lee SS et al: Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: validation in phantoms and in patients with chronic liver disease. J Magn Reson Imaging. 33(6):1390-8, 2011 Mansour S et al: Non-alcoholic steatohepatitis mimicking liver metastasis in obesity surgery. Dig Endosc. 23(4):316-8, 2011 Marsman HA et al: Hepatic steatosis assessment with CT or MRI in patients with colorectal liver metastases after neoadjuvant chemotherapy. J Surg Oncol. 104(1):10-6, 2011 Rastogi A et al: Steatosis in chronic hepatitis B: prevalence and correlation with biochemical, histologic, viral, and metabolic parameters. Indian J Pathol Microbiol. 54(3):454-9, 2011 Meng K et al: Metabolic syndrome and ectopic fat deposition: what can CT and MR provide? Acad Radiol. 17(10):1302-12, 2010 Kalra N et al: Chemical shift magnetic resonance imaging is helpful in detecting hepatic steatosis but not fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). Ann Hepatol. 8(1):21-5, 2009 Ma X et al: Imaging-based quantification of hepatic fat: methods and clinical applications. Radiographics. 29(5):1253-77, 2009 Tobari M et al: Imaging of nonalcoholic steatohepatitis: advantages and pitfalls of ultrasonography and computed tomography. Intern Med. 48(10):739-46, 2009 Vuppalanchi R et al: Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: Selected practical issues in their evaluation and management. Hepatology. 49(1):306-17, 2009 Younossi ZM et al: Metabolic syndrome, non-alcoholic fatty liver disease and hepatitis C virus: impact on disease progression and treatment response. Liver Int. 29 Suppl 2:3-12, 2009 Zhong L et al: Nonalcoholic fatty liver disease: quantitative assessment of liver fat content by computed tomography, magnetic resonance imaging and proton magnetic resonance spectroscopy. J Dig Dis. 10(4):315-20, 2009 Bahl M et al: Liver steatosis: investigation of opposed-phase T1-weighted liver MR signal intensity loss and visceral fat measurement as biomarkers. Radiology. 249(1):160-6, 2008 Castera L: Non-invasive diagnosis of steatosis and fibrosis. Diabetes Metab. 34(6 Pt 2):674-9, 2008 Cheung O et al: Hepatitis C infection and nonalcoholic fatty liver disease. Clin Liver Dis. 12(3):573-85, viii-ix, 2008

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Liver

Steatosis and Steatohepatitis

(Left) Axial ultrasound shows a focal hyperechoic lesion in the left lobe of the liver near the falciform ligament. (Right) Axial NECT in the same patient shows a small hypoattenuating lesion in the same area, a typical CT and US appearance and location for focal steatosis.

(Left) Axial CECT of multifocal and geographic steatohepatitis shows a geographic area of low attenuation throughout the anterior and medial segments. In addition, there are spherical and oval lesions in other segments of the liver. Blood vessels course through the zone of fatty infiltration without displacement. (Right) Photomicrograph of a biopsy specimen shows nonalcoholic steatohepatitis with features of perivenular/pericellular fibrosis . (Courtesy M. Yeh, MD, PhD.)

(Left) Axial CECT of perivascular multifocal steatosis shows multiple hypodense "masses" throughout the liver that may be mistaken for metastases. Note the tendency for the lesions to surround, but not obstruct, blood vessels and to occur near fissures in the liver. (Right) Axial CECT in the same patient shows other foci of steatosis that surround but do not distort or displace enhanced vessels.

636

Steatosis and Steatohepatitis Liver

(Left) Axial NECT shows multiple hypodense lesions that might be mistaken for multifocal tumor or infection. These were less evident on CECT (not shown). (Right) Opposed-phase T1-weighted GRE in the same patient shows focal signal drop-out in each of the lesions , indicative of multifocal steatosis. The inphase GRE images (not shown) showed no apparent abnormality. US-guided biopsy of one of the lesions confirmed this diagnosis.

(Left) Sonography of a 37year-old woman with RUQ pain shows diffuse increased, coarse echogenicity in comparison with the right kidney due to steatosis. (Right) In the same patient, there is a zone of less echogenic tissue abutting the gallbladder that has the typical location and appearance of focal sparing (normal liver in the setting of diffuse steatosis).

(Left) Axial CECT of 38-yearold woman with hepatic dysfunction while receiving chemotherapy for endometrial carcinoma shows marked enlargement and diffusely decreased attenuation of the liver in comparison to the spleen. Biopsy of the liver revealed steatohepatitis attributed to chemotherapy ("CASH"). (Right) Axial CECT in the same patient shows relative sparing of the liver around the gallbladder fossa , evident as a rim of normal density liver.

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Liver

Hepatic Injury From Toxins KEY FACTS

TERMINOLOGY

• Steatosis (fatty liver)

• Injury to liver induced by exogenous toxins, either through direct hepatotoxicity or idiosyncratic reaction

PATHOLOGY

IMAGING • • • •

Imaging may be normal Liver may be enlarged or acutely shrunken (volume loss) Sonography: Liver may show or echogenicity Amiodarone results in increased density ○ Most other toxins result in density due to steatohepatitis ± hepatocellular necrosis • May show other inflammatory changes, such as periportal or gallbladder wall edema • Volume loss of liver and ascites are bad prognostic signs

TOP DIFFERENTIAL DIAGNOSES • Hepatitis (alcoholic, viral, autoimmune) ○ Imaging cannot distinguish among causes of acute hepatitis

(Left) Axial NECT of a 41-yearold woman who developed acute liver failure after taking an excessive dose of acetaminophen shows diffuse low attenuation throughout the liver, which is due to acute massive hepatocellular necrosis rather than steatosis, although the imaging features are indistinguishable. (Right) Axial CECT section of the same patient shows only diffuse hypoattenuation throughout the liver and ascites on lower sections. The patient developed hepatic failure within 24 hours of this scan.

(Left) The same patient required urgent liver transplantation. The explanted liver shows signs of massive hepatocellular necrosis and acute inflammation. (Right) H&E of acute liver failure shows confluent necrosis with lymphoplasmacytic inflammation (left). Swelling and inflammation are seen in the remaining parenchyma (right). (Courtesy S. Kakar, MD.)

638

• Acetaminophen (paracetamol or Tylenol) ○ Most common cause of severe toxic injury in USA and Europe (40-50% of cases)

CLINICAL ISSUES • Acute abdominal pain, nausea, vomiting • May quickly progress to complete hepatic failure • Usually leads to complete recovery or liver failure within 72 hours ○ Acute liver failure must be treated with liver transplantation to avoid fatal outcome

DIAGNOSTIC CHECKLIST • Global or focal liver volume loss ± ascites = bad prognosis

Hepatic Injury From Toxins

Definitions • Injury to liver induced by exogenous toxins, either through direct hepatotoxicity or idiosyncratic reaction

IMAGING General Features • Best diagnostic clue ○ Imaging may be normal or show diffuse or density – May show other inflammatory changes, such as periportal or gallbladder wall edema – Amiodarone results in increased density; most other toxins result in density due to steatohepatitis ± hepatocellular necrosis

CT Findings • Hepatomegaly • Diffuse or multifocal hypodensity in liver ○ May represent steatosis, steatohepatitis, &/or hepatocellular necrosis • Volume loss of liver (global or lobar) ○ Bad prognostic sign ○ Often indicates massive hepatocellular necrosis • Ascites (bad prognostic sign)

Ultrasonographic Findings • Hepatomegaly • or echogenicity of liver ○ Steatosis vs. hepatic "edema" from acute injury • Periportal edema ± gallbladder wall edema

Imaging Recommendations • Best imaging tool ○ CT to detect signs of severe injury – Hepatic volume loss and ascites

DIFFERENTIAL DIAGNOSIS Hepatitis (Alcoholic, Viral, Autoimmune)

□ Liver failure or recovery within 72-96 hours after ingestion – Toxic mushrooms, poisons, carbon tetrachloride – Other medications □ Amiodarone (dense liver on NECT) □ Calcium channel blockers, steroids, anti-HIV drugs • Idiosyncratic hepatotoxins ○ Produce injury only in small proportion of individuals who are susceptible – e.g., isoniazid, halothane anesthesia, chlorpromazine, phenytoin

Microscopic Features • Cytotoxic or cholestatic injury • Amiodarone and other drugs cause phospholipidosis ○ Granular, foamy appearance of hepatocytes ○ Amiodarone gets trapped within lysozymes ○ Hepatocyte swelling • Steatohepatitis • Fibrosis or cirrhosis with progressive disease • Massive necrosis due to intrinsic or idiosyncratic hepatotoxins

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acetaminophen or other direct toxins – Acute abdominal pain, nausea, vomiting – May quickly progress to complete hepatic failure – Usually leads to complete recovery or liver failure within 72 hours – Acute liver failure must be treated with liver transplantation to avoid fatal outcome • Other signs/symptoms ○ Acute, subacute, or chronic cholestatic injury – Pruritus, jaundice

Natural History & Prognosis

Steatosis (Fatty Liver)

• For direct toxins ○ Withdrawal of toxic agent ○ Rapid recovery or death within 48 hours without transplantation

• Steatosis or steatohepatitis may result from other etiologies besides toxic injury

Treatment

• Imaging cannot distinguish among causes of acute hepatitis

Liver

TERMINOLOGY

• Liver transplantation

PATHOLOGY Staging, Grading, & Classification • Intrinsic hepatotoxins ○ Direct and predictable injury to liver – Dose dependent ○ Common agents – Acetaminophen (paracetamol or Tylenol) □ As part of deliberate suicide attempt or unintentional consumption of excessive amounts □ Most common cause of severe toxic injury in USA and Europe □ Accounts for 40-50% of cases of acute toxic injury with acute liver failure □ Threshold for injury is lowered by coexisting alcoholic or nonalcoholic steatohepatitis

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Global or focal liver volume loss ± ascites = bad prognosis

SELECTED REFERENCES 1.

2. 3.

Heard K et al: A single-arm clinical trial of a 48-hour intravenous Nacetylcysteine protocol for treatment of acetaminophen poisoning. Clin Toxicol (Phila). 52(5):512-8, 2014 Corsini A et al: Drug-induced liver injury: the role of drug metabolism and transport. J Clin Pharmacol. 53(5):463-74, 2013 Shah AD et al: Understanding lactic acidosis in paracetamol (acetaminophen) poisoning. Br J Clin Pharmacol. 71(1):20-8, 2011

639

Liver

Hepatic Injury From Toxins

(Left) Axial arterial phase CECT in a 29-year-old man with acute severe hepatic dysfunction shows an enlarged heterogeneous liver. (Right) Another arterial phase CT image in the same patient shows more of the heterogeneous enlarged liver, along with periportal edema . This was attributed to the combined toxic effects of alcohol abuse and acetaminophen used to treat a hangover.

(Left) This portal venous phase image in the same patient shows the hepatomegaly and periportal edema, but the heterogeneity of the liver is less apparent. The liver injury represents a combination of steatosis and hepatocellular necrosis. (Right) CT in the same patient with acute hepatic injury from alcohol and acetaminophen shows nonspecific gallbladder wall edema .

(Left) Axial CT section through the pelvis in the same patient shows ascites , a bad prognostic sign in the setting of acute toxic hepatic injury. (Right) Multiacinar hemorrhagic necrosis , congestion , and lack of inflammation with sparing of periportal hepatocytes are typical of acetaminophen toxicity but can also be seen in acute ischemia and acute Budd-Chiari syndrome. (Courtesy S. Kakar, MD.)

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Hepatic Injury From Toxins Liver

(Left) Axial CT in a 24-year-old man with acute hepatic failure probably due to alcohol and drug abuse shows a heterogeneous liver with evidence of volume loss (capsular retraction) . A large amount of ascites and pleural effusions are also noted. These are ominous findings, usually associated with death or requiring urgent transplantation. (Right) Lower CT section in the same patient shows more of the damaged liver with volume loss and ascites. The patient died of acute hepatic failure.

(Left) Frontal digital radiograph in a 41-year-old woman with intractable arrhythmias and abnormal liver function shows an implantable cardioverter defibrillator (AICD) with numerous wire leads to the heart. (Right) Axial NECT in the same patient shows some of the cardiac leads from the AICD .

(Left) Another NECT section in the same patient shows diffuse increased density within the liver due to amiodarone deposition. Amiodarone is an iodinecontaining antiarrhythmic that may cause hepatic (and pulmonary) toxicity. (Right) Ballooned hepatocytes containing abundant Mallory hyaline bodies are surrounded by neutrophils, known as satellitosis . This is a frequent feature of amiodarone toxicity. Steatosis may or may not be present. (Courtesy L. Lamps, MD.)

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Liver

Cirrhosis KEY FACTS

TERMINOLOGY • Chronic liver disease characterized by diffuse parenchymal injury, extensive fibrosis, and conversion of liver architecture into structurally abnormal nodules • 3rd most common cause of mortality among middle-aged men in USA; 10th most common worldwide

IMAGING • Nodular contour, widened fissures, and enlarged caudate lobe with ascites, splenomegaly, and varices • Classification by etiology and severity is more useful than by morphology • Siderotic regenerative nodules ○ Hyperdense on NECT, isodense on CECT ○ Hypointense on T2 and GRE MR ○ 3-10 mm in size • Vascular derangements ○ Arterioportal and portovenous shunts ○ Varices (gastroesophageal, caput medusae, etc.)

(Left) Graphic shows a cirrhotic liver with a nodular surface contour and an increase in the caudate to right lobe ratio, measured from the branch point of the right portal vein to the edges of the caudate and right lobes, respectively. Note the bands of fibrosis and ascites. (Right) Axial CECT shows a cirrhotic liver and large varices . Note the enlarged caudate lobe , which is as wide as the right lobe, although the caudate lobe is normally no more than 60% of the width of the right lobe.

(Left) Axial NECT in this 50year-old woman with primary biliary cirrhosis shows innumerable small hyperdense regenerative nodules , surrounded by lace-like fibrosis. (Right) The nodules disappear into the background cirrhotic liver on this CECT from the same patient. Prominent porta hepatis lymphadenopathy , another typical feature of primary biliary cirrhosis, is also noted. Primary biliary cirrhosis is an autoimmune disease that typically affects women in their 5th or 6th decade.

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• Fibrosis: Diffuse, lace-like, thick, or confluent foci ○ Hypointense on T1W; hyperintense on T2W MR • Cirrhosis-induced hepatocellular carcinoma (HCC) ○ Heterogeneous enhancement on arterial phase; usually hypodense on venous and delayed phase CT + MR ○ Hyperintense on T2W MR ○ Bright on DWI MR ○ ± capsule, fat, venous invasion, metastases

TOP DIFFERENTIAL DIAGNOSES • • • • •

Treated liver metastases or lymphoma Budd-Chiari syndrome Hepatic sarcoidosis Primary portal vein thrombosis Nodular regenerative hyperplasia

DIAGNOSTIC CHECKLIST • MR has advantage in detection and characterization of focal nodules within cirrhotic liver

Cirrhosis

Definitions • Chronic liver disease characterized by diffuse parenchymal injury, extensive fibrosis, and conversion of liver architecture into structurally abnormal nodules

IMAGING General Features • Best diagnostic clue ○ Nodular contour, widened fissures, and enlarged caudate lobe with ascites, splenomegaly, and varices • Size ○ Moderate to advanced cirrhosis: Decreased size – Earlier disease: May be enlarged – Especially in primary biliary cirrhosis • Key concepts ○ Common end response of liver to variety of insults and injuries ○ Classification by morphology (not very useful) – Micronodular (Laennec) cirrhosis □ Usually due to alcoholism – Macronodular (postnecrotic) cirrhosis □ Usually viral hepatitis ○ Classification by etiology and severity more useful

CT Findings • Atrophy of right lobe and medial segment of left lobe • Enlarged caudate lobe and lateral segment of left lobe ○ Caudate: Right lobe ratio often > 1.0 in cirrhosis ○ Caudate is normally < 60% width of right lobe • Widened fissures between segments/lobes • Deep gallbladder (GB) fossa ○ GB often lies against anterolateral abdominal wall • Vascular derangements ○ Varices (gastroesophageal, caput medusae, etc.) ○ Arterioportal and portovenous shunts – Arterioportal (AP) shunts are usually peripheral, wedge-shaped, small; seen only on arterial phase – Small AP shunt difficult to distinguish from very small hepatocellular carcinoma (HCC) □ Follow-up imaging (CT or MR) in 3-6 months is sufficient for surveillance ○ "Corkscrew" hepatic arterial branches – Enlarged and displaced around regenerative nodules • Splenomegaly • Nodular liver contour (not apparent in all) • Siderotic regenerative nodules ○ Hyperdense on NECT, isodense on CECT ○ Most regenerative nodules are not detected by CT • Fibrotic and fatty changes ○ Fibrosis: Diffuse, lace-like, thick bands or confluent "masses" – More apparent on NECT (hypodense) – May show persistent enhancement on delayed CECT (or contrast-enhanced MR) □ Distinguishes from HCC, which shows washout on delayed imaging ○ Fatty changes: Diffuse or geographic areas of low attenuation

– Usually limited to alcoholic hepatitis with early cirrhosis • Peribiliary cysts ○ Cystic dilation of peribiliary gland in wall of large bile ducts ○ Range in size from 2 mm to 2 cm ○ Resemble string of pearls or grapes on a stem • Cirrhosis-induced HCC ○ CECT – Heterogeneous enhancement on arterial phase; usually iso- to hypodense on venous and delayed phase scans – ± capsule, portal or hepatic venous invasion, metastases

Liver

TERMINOLOGY

MR Findings • Siderotic regenerative nodules: Paramagnetic effect of iron within nodules ○ T1WI: Hypointense ○ T2WI: Increased conspicuity of low signal intensity ○ T2 gradient-echo and fast low-angle shot (FLASH) images – Markedly hypointense (best sequence for detection) ○ Gamna-Gandy bodies (siderotic nodules in spleen) – T1WI and T2WI: Hypointense • Dysplastic regenerative nodules ○ T1WI: Hyperintense; T2WI: Hypointense ○ Minimal vascularity ○ Take up and retain hepatobiliary MR contrast agents on delayed phase – Most specific test to distinguish from HCC • HCC nodule ○ T2WI: Hyperintense ○ T1 C+: Increased enhancement on arterial phase – Washes out to hypointense on venous and delayed phases ○ Diffusion-weighted imaging – Restricted diffusion (bright signal) within HCC ○ Rarely take up or retain hepatobiliary MR contrast agents • Fibrotic and fatty changes ○ T1WI: Fibrosis = hypointense; fat = hyperintense ○ T2WI: Fibrosis = hyperintense; fat = hypointense • MR elastography ○ Shows promise in noninvasive evaluation of extent of liver fibrosis

Ultrasonographic Findings • Grayscale ultrasound ○ Nodular liver contour and parenchyma ○ Increased and coarsened liver echogenicity – Decreased visualization of deep liver ○ Features of portal hypertension – Increased pulsatility of portal vein Doppler tracing – Dilated hepatic and splenic arteries with increased flow • Color Doppler ○ Used to determine portal vein patency and direction of flow – Hepatofugal is sign of severe portal hypertension • Ultrasound is of most value and accuracy in screening patients with less advanced chronic liver disease 643

Liver

Cirrhosis ○ Less accurate in detecting or characterizing nodules within cirrhotic liver ○ Presence of fibrosis, fat, regenerative nodules makes detection of HCC very difficult

Imaging Recommendations • Best imaging tool ○ Multiphasic CT or MR • Protocol advice ○ US is suitable for screening until cirrhosis is established ○ CECT is preferable in acutely ill patients or those with ascites ○ MR is preferable in alcoholic cirrhosis and for detection/distinction of hepatic nodules – Include delayed phase MR or CT (5-10 minutes) – Hepatobiliary MR contrast agents may aid in detection of HCC □ Gadoxetate (Eovist, Primovist) is retained in normal liver, variably in cirrhotic liver, rarely in HCC

DIFFERENTIAL DIAGNOSIS Treated Liver Metastases or Lymphoma • Simulates nodules, fibrosis, volume loss of cirrhotic liver • Breast carcinoma metastases to liver ○ May result in "pseudocirrhosis," especially after treatment

Budd-Chiari Syndrome • Liver damaged but usually no bridging fibrosis • Occluded or narrowed IVC ± hepatic veins • Chronic phase: "Large regenerative nodules" ○ Hypervascular foci mimic HCC – But no washout on delayed imaging – Retain gadoxetate, unlike most HCC • Central hypertrophy, peripheral atrophy

Hepatic Sarcoidosis • May simulate or cause cirrhosis • Hypodense nodules and lymphadenopathy • Look for thoracic and clinical correlation ○ Including peribronchial nodularity and lymphadenopathy

Primary Portal Vein Thrombosis • May be result of hypercoagulable state • Chronic hepatic ischemia with peripheral atrophy, central hypertrophy, varices • Clue: Cavernous transformation of portal vein; infarcts or ischemia of other organs

Nodular Regenerative Hyperplasia • By definition lacks fibrosis • Can cause portal hypertension and nodules

PATHOLOGY General Features • Etiology ○ Alcohol: No longer most common cause of cirrhosis in USA and Europe ○ Etiology of cirrhosis in USA – Hepatitis C (~ 25%) – Alcoholic liver disease (~ 20%) 644

– "Cryptogenic" (believed to be due to nonalcoholic steatohepatitis [NASH] in most cases) (~ 20%) – Hepatitis C and alcohol (~ 15%) – Hepatitis B (± hepatitis D) (~ 15%) – Miscellaneous (~ 5%) □ Autoimmune hepatitis □ Primary biliary cirrhosis □ Secondary biliary cirrhosis (obstruction) □ Primary sclerosing cholangitis □ Hemochromatosis □ Wilson disease □ -1 antitrypsin deficiency □ Granulomatous disease (e.g., sarcoidosis) □ Drug-induced liver disease (e.g., methotrexate, amiodarone) □ Venous outflow obstruction (Budd-Chiari and venoocclusive disease) □ Chronic right-sided heart failure • Due to combination of cell death, fibrosis, and regeneration

Staging, Grading, & Classification • Grading of severity: Child-Pugh classification ○ "Points" assigned for ascites, encephalopathy, serum bilirubin, serum albumin, prothrombin time ○ Correlates well with survival (1 year) – Child-Pugh A = 100% – Child-Pugh B = 80% – Child-Pugh C = 45% • Model for End-Stage Liver Disease (MELD) ○ Based on assessment of etiology of cirrhosis, serum creatinine and bilirubin level, and international normalized ratio (INR)

Gross Pathologic & Surgical Features • Alcoholic and other causes of micronodular cirrhosis macronodular cirrhosis with progression ○ End-stage cirrhotic livers have similar gross morphologic changes ○ Small, hard, nodular liver with linear and confluent fibrosis

Microscopic Features • Fibrosis ○ Present in all cirrhotic livers ○ Collagen and other extracellular matrix deposited around portal tracts • Vascular derangements ○ Occlusion of fenestrations in sinusoids – Converts sinusoids into capillaries ○ Sclerosis and thrombosis of portal tracts – Increases resistance (portal hypertension) – Found at microscopic level in most cases, less commonly in large vessels ○ Arteriovenous and portovenous shunts – Important in imaging (may simulate HCC) – Contributes to hepatocyte death (ischemia and loss of portal vein nutrients) • Regeneration ○ Occurs in almost all cases ○ Results in regenerative nodules, often surrounded by fibrous bands

Cirrhosis

DIAGNOSTIC CHECKLIST

Liver

○ May compress bile ducts and blood vessels, contributing to damage

Consider

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Signs of portal hypertension – Splenomegaly, varices, ascites ○ Fatigue, jaundice, ascites, encephalopathy ○ Gynecomastia and testicular atrophy in males • Other signs/symptoms ○ Hepatorenal and hepatopulmonary syndromes ○ Coagulopathy (due to decreased hepatic synthetic function) ○ Hepatic encephalopathy ○ Hepatic hydrothorax – Usually right sided – Due to ascites traversing diaphragm into chest ○ Cardiomyopathy ○ Portal hypertensive colopathy and gastropathy – Due to portal hypertension and hypoproteinemia – Results in submucosal edema of wall of colon ± stomach ○ Hepatocellular carcinoma (HCC) – All patients with cirrhosis have markedly risk of developing HCC – Patients with most forms of chronic liver disease are not at risk of HCC until cirrhosis develops □ Exception is chronic hepatitis B (may develop HCC before cirrhosis)

Demographics • Age ○ Many patients die in 5th or 6th decade – Highly variable depending on etiology and severity of underlying etiology • Gender ○ M>F • Epidemiology ○ 3rd leading cause of death for men age 34-54 years in USA – 35,000 deaths per year ○ 10th leading cause of mortality worldwide

Natural History & Prognosis • Mortality due to complications ○ Progressive liver failure ○ Complication related to portal hypertension – Variceal hemorrhage, infected ascites ○ HCC • Prognosis ○ Advanced cirrhosis is irreversible ○ Prognosis depends on etiology and severity – 10-year survival from diagnosis ~ 50%

• Rule out other causes of nodular dysmorphic liver ○ Imaging can strongly suggest cirrhosis ○ Biopsy is necessary for establishing presence, etiology, and severity

Image Interpretation Pearls • Nodular liver contour; lobar atrophy and hypertrophy • Regenerative nodules, ascites, splenomegaly, varices • Ultrasound is excellent for surveillance patients with chronic liver disease ○ Especially in thin patients who have not yet developed cirrhosis ○ Once cirrhosis has developed, US screening is less effective ○ Difficult to distinguish HCC from other types of nodules within cirrhotic liver • Multiphasic CECT and MR are accurate in detecting HCC > 2 cm in size ○ MR has advantage in detection and characterization of focal nodules within cirrhotic liver

Reporting Tips • Specifically evaluate all hepatic vessels ○ Hepatic and portal veins (for thrombosis, tumor invasion) ○ Presence and type of varices and collaterals – e.g., spontaneous splenorenal shunt ○ Hepatic artery for congenital variations (e.g., replaced origin from SMA) ○ Median arcuate ligament compression of celiac axis – May decrease flow to liver allograft – Can easily be relieved if known prior to transplantation

SELECTED REFERENCES 1.

2.

3.

4. 5.

6.

7. 8.

Beland MD et al: A pilot study estimating liver fibrosis with ultrasound shearwave elastography: does the cause of liver disease or location of measurement affect performance? AJR Am J Roentgenol. 203(3):W267-73, 2014 Jha RC et al: LI-RADS categorization of benign and likely benign findings in patients at risk of hepatocellular carcinoma: a pictorial atlas. AJR Am J Roentgenol. 203(1):W48-69, 2014 Khalili K et al: Indeterminate 1-2-cm nodules found on hepatocellular carcinoma surveillance: biopsy for all, some, or none? Hepatology. 54(6):2048-54, 2011 Starr SP et al: Cirrhosis: diagnosis, management, and prevention. Am Fam Physician. 84(12):1353-9, 2011 Vivarelli M et al: Liver transplantation for hepatocellular carcinoma on cirrhosis: strategies to avoid tumor recurrence. World J Gastroenterol. 17(43):4741-6, 2011 European Association for the Study of the Liver: EASL clinical practice guidelines on the management of ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome in cirrhosis. J Hepatol. 53(3):397-417, 2010 Boll DT et al: Diffuse liver disease: strategies for hepatic CT and MR imaging. Radiographics. 29(6):1591-614, 2009 Hanna RF et al: Cirrhosis-associated hepatocellular nodules: correlation of histopathologic and MR imaging features. Radiographics. 28(3):747-69, 2008

Treatment • Advanced stage: Liver transplantation

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Liver

Cirrhosis

(Left) MR shows obvious signs of cirrhosis with widening of the fissures, right lobe atrophy, and large varices . Within the spleen are innumerable small lesions that are especially evident as hypointense foci on this GRE T1WI contrast-enhanced image , representing Gamna-Gandy bodies. (Right) Sagittal US shows a coarse echotexture of the liver that is typical, but not diagnostic, of cirrhosis.

(Left) Axial CECT in a patient with autoimmune hepatitis and primary sclerosing cholangitis (PSC) shows a nodular, cirrhotic liver with splenomegaly, ascites, and varices . The intrahepatic ducts are dilated with an abnormal arborization, suggestive of PSC. (Right) Axial CECT in the same patient shows the lobular contour of the liver and the hypertrophy of the caudate lobe with atrophy of the entire peripheral liver, all characteristic of cirrhosis due to PSC.

(Left) Arterial phase CECT shows a small hypervascular lesion that was isodense to the liver on all other phases. This lesion was not evident on repeat CT or MR over the next 2 years and presumably represents a small arterioportal shunt. (Right) The small vascular lesion is not evident on this portal venous phase image in the same patient nor was it visible on delayed phase imaging (not shown).

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Cirrhosis Liver

(Left) This patient had cirrhosis due to PSC. NECT shows a lobulated contour of the liver with relatively lower density atrophic peripheral liver, and hypertrophied and hyperdense, large, nodular segments of the deep right and caudate segments . (Right) On CECT (same patient) the liver becomes more homogeneous in attenuation. Note the prominent nodes in cardiophrenic regions. The intrahepatic ducts are not dilated but were found to be beaded and strictured on ERCP.

(Left) Axial CECT (same patient) shows marked caudate hypertrophy and rounded contours of the liver. PSC tends to result in disproportionate atrophy of the peripheral segments of liver, whereas the more central hepatic segments hypertrophy, presumably due to preserved biliary drainage of those segments that drain more directly into the central bile ducts. (Right) Axial CT (same patient) shows the peculiar rounded contours of the liver due to chronic PSC. Note the prominent porta hepatis nodes .

(Left) Axial T2WI MR shows innumerable subcentimeter hypointense nodules that are typical of cirrhotic regenerative nodules. (Right) Axial CECT in a patient with cardiac cirrhosis shows a mottled enhancement of the hepatic parenchyma and massive distention of the inferior vena cava and hepatic veins . Unrecognized or untreated right heart failure or constrictive pericarditis can lead to acute or irreversible hepatic damage.

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Liver

Cirrhosis

(Left) Axial arterial phase CECT shows arterioportal (AP) shunts as multiple, small, wedge-shaped, peripheral hypervascular lesions . (Right) More caudal arterial phase CT of the same patient shows an additional peripheral hypervascular lesion . Also note the "corkscrew" enlarged hepatic arterial branch and the widened fissures, all typical of cirrhosis.

(Left) Portal venous phase CT of same patient shows that all the peripheral hypervascular lesions have become isodense to background liver, typical of arterioportal shunts. (Right) Delayed phase CT of the same patient shows there is no sign of washout from the sites of shunts. AP shunts are common within the cirrhotic liver. Imaging features that favor AP shunt over hepatocellular carcinoma (HCC) include peripheral and subcapsular location, small size, wedge shape, and no corresponding lesion on venous or delayed phase imaging.

(Left) Axial T2WI FS MR shows a small cirrhotic liver and ascites. Also shown are waterintensity lesions in the portal triads that do not arborize (branch) as bile ducts and are spherical in shape, representing peribiliary cysts. (Right) CT of a patient with cirrhosis shows that the portal vein branches are surrounded by a collar of low density, some of which probably represent periportal edema. However, there are also discrete low-density focal lesions that represent periportal cysts.

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Cirrhosis Liver

(Left) Axial NECT of a 78-yearold woman with chronic hepatitis C and cirrhosis shows a mass in the lateral segment that has 2 distinct components, including a fatdensity left half and a soft tissue-density right half . (Right) Axial T1WI fatsuppressed MR in the same patient shows low signal within the fatty component of the mass and only relatively hyperintensity within the right lateral component .

(Left) Axial T2WI of the same patient shows that the right component has MR characteristics of a dysplastic nodule, hypointense on T2WI , while the other portion of the lesion shows relatively bright signal on this nonfat-suppressed T2WI. (Right) On this T2WI without fat suppression, the fatty component of the mass is hyperintense and represents HCC, while the other half of the nodule is hypointense and is a dysplastic nodule .

(Left) Fat-suppressed T2WI of the same patient shows signal loss from the fat-containing part of the mass , which is strongly suggestive of HCC in a cirrhotic liver. (Right) Axial T1WI GRE MR shows signal dropout from the HCC . At resection, this was an HCC with fatty components within a larger dysplastic nodule. In addition, there are innumerable tiny cirrhotic regenerative nodules that are most evident as tiny hypointense foci on this GRE image.

649

Liver

Cirrhosis

(Left) On this arterial phase CECT in a patient with cirrhosis and HCC, the mass is heterogeneously hyperdense and hypervascular . (Right) On portal venous (hepatic) phase CECT in the same patient, the mass is iso- to hypodense to the liver. These are typical features of HCC, particularly for a tumor detected as part of a surveillance program for patients with known cirrhosis who are at risk for developing HCC.

(Left) Arterial phase CECT of a 56-year-old man with chronic viral hepatitis shows a subtle hypervascular mass . This proved to be HCC. (Right) A more caudal CECT section in the same patient shows signs of cirrhosis, including widened fissures, a big caudate lobe, and an enlarged "corkscrew" hepatic artery .

(Left) Portal venous (hepatic) phase image in the same patient shows the mass , an HCC, much more clearly due to washout of contrast medium from the lesion. (Right) In the same patient, the tumor was treated with intraarterial chemotherapy mixed with Ethiodol, an oily iodinated contrast medium that results in dense, very persistent enhancement of the tumor . The tumor responded well to treatment, but liver function deteriorated, as evidenced by volume loss and development of ascites.

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Cirrhosis Liver

(Left) NECT shows a lowattenuation hepatic lesion within the anterior and medial segments; the overlying hepatic capsule is retracted. These findings are characteristic of confluent hepatic fibrosis, which is common in advanced cirrhosis. (Right) The focal confluent fibrotic lesion in the same patient becomes almost isodense to the liver on this portal venous phase CECT. Also evident are varices , splenomegaly, and ascites, typical manifestations of portal hypertension.

(Left) Axial CT of the same patient shows a massive paraumbilical collateral vein and a thick-walled stomach that might represent portal hypertensive gastropathy. (Right) More caudal CT section of the same patient shows periumbilical varices (caput medusae) , ascites, and mesenteric edema that accentuates the mesenteric vessels and their enveloping fat.

(Left) Axial CECT shows typical signs of cirrhosis (wide fissures; increased caudate:right lobe ratio) and portal hypertension, including splenomegaly and ascites. (Right) In the same patient, note the thickened wall of the ascending colon , which simulates findings seen with colitis. On colonoscopy, there was no mucosal inflammation, only venous engorgement, known as portal hypertensive colopathy.

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Liver

Primary Biliary Cirrhosis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Chronic progressive cholestatic liver disease characterized by nonsuppurative destruction of interlobular bile ducts ○ Leads to advanced fibrosis, cirrhosis, and liver failure

• Postnecrotic (viral) or alcoholic cirrhosis • Hepatic lymphoma and metastases • Sarcoidosis and amyloidosis

IMAGING

PATHOLOGY

• In less advanced disease, liver is enlarged and smooth • Regenerative nodules are often evident ○ 3-10 mm, hyperdense on NECT; hypointense on T2W MR • Lymphadenopathy is prominent feature • Lace-like fibrosis is a prominent feature ○ Hypointense on T1W, hyperintense on T2W MR • Signs of portal hypertension may precede biopsy evidence of cirrhosis • Hepatocellular carcinoma: Less frequent in primary biliary cirrhosis than with other causes of cirrhosis

• May coexist with other autoimmune disease of liver ○ Including primary sclerosing cholangitis and autoimmune hepatitis

(Left) Gross pathology cut section of an explanted liver shows regenerating nodules (dark red ) surrounded by lace-like fibrosis (pale pink to white bands) from a patient with liver failure due to primary biliary cirrhosis (PBC). (Right) The florid duct lesion with nonnecrotizing is typical of granulomas PBC. (Courtesy M. Yeh, MD, PhD.)

(Left) Axial T1WI MR shows lace-like fibrosis of the liver, consisting of interlacing lowintensity bands of tissue. (Right) Axial T2WI MR in the same patient shows innumerable subcentimeter, hypointense regenerating nodules surrounded by thin bands of hyperintense fibrosis. PBC tends to give the most evident and uniform distribution of regenerative nodules, surrounded and separated by thin bands of fibrosis.

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CLINICAL ISSUES • ~ 95% of patients are female ○ Typical onset of symptoms in 40- to 50-year-old women • Fatigue and pruritus are early symptoms • Takes ~ 7-10 years to progress to liver failure • Serum antimitochondrial antibody tests highly sensitive and specific (positive in 95%)

Primary Biliary Cirrhosis

Abbreviations • Primary biliary cirrhosis (PBC)

Definitions • Chronic progressive cholestatic liver disease characterized by nonsuppurative destruction of interlobular bile ducts ○ Leads to advanced fibrosis, cirrhosis, and liver failure

IMAGING

○ Periportal halo • No dilation of intrahepatic bile ducts on T2WI or MRCP

Ultrasonographic Findings • Grayscale ultrasound ○ Major bile ducts are patent, hepatomegaly (early), liver echogenicity, gallstones, lymphadenopathy ○ Usual signs of cirrhosis (heterogeneity, nodularity, poor sound transmission) ○ Usual signs of portal hypertension (varices, splenomegaly, ascites)

General Features

Nuclear Medicine Findings

• Best diagnostic clue ○ Hepatomegaly, lace-like fibrosis, and regenerative nodules in middle-aged woman with pruritus • Key concepts ○ In less advanced disease, liver is enlarged and smooth – With progression, liver loses volume, becoming more nodular and dysmorphic – Late-phase PBC resembles other causes of cirrhosis

• Tc-99m iminodiacetic acid scan ○ Diffuse, uniform, hepatic isotope retention and normal major bile ducts ○ Normal visualization of gallbladder but reduced gallbladder ejection fraction and ejection rate

CT Findings • NECT ○ Heterogeneous liver parenchyma in both advanced and less advanced cases of PBC – Regenerative nodules are often evident (> 50%) on NECT □ Hyperdense, 3-10 mm, surrounded by lace-like fibrosis □ Features are more prevalent in PBC than in other forms of cirrhosis ○ Patchy, poorly defined regions of low attenuation – Nonspecific; often correlates with regions of confluent fibrosis – Confluent hepatic fibrosis may be seen in advanced PBC (3%) • CECT ○ Regenerative nodules isoattenuating to liver on portal venous phase ○ Fibrosis is not as evident; isodense to liver ○ Lymphadenopathy is more prominent feature in PBC than in other etiologies of chronic liver disease – Nodes 1.5-3 cm in diameter – Location: Porta hepatis, cardiophrenic, upper abdominal – Lymph nodes show moderate and homogeneous contrast enhancement ○ Signs of portal hypertension with advanced PBC (varices, ascites, splenomegaly) ○ Hepatocellular carcinoma (HCC) – Usually heterogeneously hypervascular, best seen on arterial phase imaging □ Washes out to become iso- to hypodense on portal venous and delayed imaging □ Less frequent than with other causes of cirrhosis

MR Findings • Regenerative nodules (siderotic): conspicuity of low signal intensity on T2WI; markedly hypointense on GRE images • Fibrosis: Hypointense on T1WI, hyperintense on T2WI

Liver

TERMINOLOGY

Other Modality Findings • Cholangiography: Irregular course and caliber of larger intrahepatic bile ducts ○ Mostly reflects effects of cirrhotic nodules, rather than primary bile duct disease ○ arborization = "tree in winter" appearance

Imaging Recommendations • Best imaging tool ○ Multiphasic CECT or MR • Protocol advice ○ NECT and contrast-enhanced CT or MR

DIFFERENTIAL DIAGNOSIS Postnecrotic (Viral) or Alcoholic Cirrhosis • Alcoholic: Often has combination of steatosis and cirrhosis ○ Less prominent lymphadenopathy • Diagnosis is based on history, biopsy results, viral studies, etc.

Hepatic Lymphoma and Metastases • Homogeneous/heterogeneous hepatomegaly and hypodense focal lesions • Secondary lymphoma is either multinodular or diffusely infiltrative with lymphadenopathy

Sarcoidosis and Amyloidosis • Both may simulate or cause cirrhosis • Lymphadenopathy is thoracic and abdominal • Characteristic lung disease in sarcoid

Myeloproliferative Disorders • Hepatomegaly associated with splenomegaly and generalized lymphadenopathy (e.g., chronic leukemia, agnogenic myeloid metaplasia)

Opportunistic Infection • In immunocompromised hosts • Infection by fungi, mycobacteria, viruses, bacteria ○ Heterogeneous hepatosplenomegaly ± abdominal lymphadenopathy may be indistinguishable by imaging alone

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Liver

Primary Biliary Cirrhosis

PATHOLOGY General Features • Etiology ○ Cause of PBC is unknown; probably due to inherited abnormality of immunoregulation • Genetics ○ Genetic factors play part in development of PBC but not inherited in any recessive/dominant pattern ○ 1,000x greater prevalence in families with 1 affected member • Associated abnormalities ○ Often have at least 1 other autoimmune disease (84%), including thyroiditis, scleroderma, rheumatoid arthritis, Sjögren syndrome ○ May coexist with other autoimmune liver disease – Including primary sclerosing cholangitis and autoimmune hepatitis

– Typical onset of symptoms in 40- to 50-year-old women – Takes ~ 7-10 years to progress to liver failure • Gender ○ ~ 95% of patients are female • Epidemiology ○ Accounts for 0.6-2.0% of deaths from cirrhosis ○ 3rd most common indication for liver transplantation in adults ○ Prevalence: 19-151 cases per million people ○ Incidence: 3.9-15 cases per million people each year

Natural History & Prognosis

• Early: Diffusely enlarged liver with uniform and prominent regenerative nodules and lace-like fibrosis ○ Late: Small cirrhotic liver with widened fissures and signs of portal hypertension • Gallbladder and larger bile ducts are normal

• Natural history of PBC is not fully understood ○ Progressive disease in almost all patients; rate of progression varies • Varices may develop and bleed relatively early in course of PBC, well before jaundice or true cirrhosis manifests • HCC in PBC tends to be well differentiated ○ Fewer cases of HCC in patients with PBC than in those with viral or alcoholic cirrhosis • Complication: Liver failure ○ Usually within 7-10 years of diagnosis • Prognostic factors: Patient age, serum bilirubin level, prothrombin time, and histopathology

Microscopic Features

Treatment

• Characterized by destruction of small intrahepatic bile ducts, portal inflammation, and progressive scarring

• Ursodeoxycholic acid to treat pruritus • Liver transplantation ○ 1-year post-transplant survival rate has increased to 90% ○ PBC can recur after transplantation at rate of 1–2% per year

Gross Pathologic & Surgical Features

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Fatigue (78%) and pruritus (60%) precede histologic evidence of cirrhosis ○ Diffuse hepatomegaly (11%): Early > late disease ○ Portal hypertension: Varices, splenomegaly, ascites ○ Xanthomas (25%), cholelithiasis (39%) ○ Jaundice is later manifestation of disease but may be seen at presentation in some ○ Osteopenia due to hepatic osteodystrophy, erosive arthritis, intraosseous lytic defects, osteoporosis • Clinical profile ○ Lab data – Cholestatic pattern: Alkaline phosphatase and glutamyltransferase levels disproportionately higher than aminotransferase, serum IgM levels □ Serum antimitochondrial antibody tests highly sensitive and specific (positive in 95%) □ Elevated serum bilirubin is sign of poor prognosis □ Antinuclear antibodies are present in 70% (may indicate overlap with autoimmune hepatitis and worse prognosis) ○ Diagnosis: Percutaneous liver biopsy; findings provide confirmatory information and assist in determination of histologic stage of disease

DIAGNOSTIC CHECKLIST Consider • In middle-aged women presenting with fatigue, pruritus, hepatomegaly, and upper abdominal lymphadenopathy

Image Interpretation Pearls • Presence of lace-like fibrosis, prominent lymphadenopathy, and hepatomegaly (early) along with positive antimitochondrial antibody test

SELECTED REFERENCES 1.

2. 3. 4.

5. 6. 7.

Demographics • Age ○ Onset between ages 30-65 years 654

8.

Karlsen TH et al: Review article: controversies in the management of primary biliary cirrhosis and primary sclerosing cholangitis. Aliment Pharmacol Ther. 39(3):282-301, 2014 Granito A et al: Antinuclear antibodies as ancillary markers in primary biliary cirrhosis. Expert Rev Mol Diagn. 12(1):65-74, 2012 Chuang N et al: Update on the epidemiology of primary biliary cirrhosis. Expert Rev Gastroenterol Hepatol. 5(5):583-90, 2011 Grattagliano I et al: Long-term ursodeoxycholate improves circulating redox changes in primary biliary cirrhotic patients. Clin Biochem. 44(17-18):1400-4, 2011 Kim KA et al: The diagnosis and treatment of primary biliary cirrhosis. Korean J Hepatol. 17(3):173-9, 2011 Mendes F et al: Recurrent and de novo autoimmune liver diseases. Clin Liver Dis. 15(4):859-78, 2011 Kuiper EM et al: Improved prognosis of patients with primary biliary cirrhosis that have a biochemical response to ursodeoxycholic acid. Gastroenterology. 136(4):1281-7, 2009 Blachar A et al: Primary biliary cirrhosis: clinical, pathologic, and helical CT findings in 53 patients. Radiology. 220(2):329-36, 2001

Primary Biliary Cirrhosis Liver

(Left) Cholestasis in PBC is characterized by rarefied and swollen hepatocytes adjacent to the portal tracts. (Courtesy M. Yeh, MD, PhD.) (Right) Both PBC and autoimmune cholangitis (AMA-negative PBC) may have florid duct lesions, bile duct injury, and ductular reaction. (Courtesy M. Yeh, MD, PhD.)

(Left) NECT of a 53-year-old woman with PBC first diagnosed 5 years prior shows a heterogeneous liver with innumerable small hyperdense regenerating nodules separated by a lace-like network of lower density tissue, typical of the pattern of fibrosis often seen in patients with PBC. (Right) CECT of the same patient shows a more homogeneous-appearing liver, as the regenerating nodules and fibrosis have become nearly isodense with the surrounding liver. Enlarged porta hepatis lymph nodes are noted.

(Left) CECT of the same patient shows additional prominent lymphadenopathy , a typical feature of PBC. (Right) Photograph of the cut section of the explanted liver from the same patient shows a nodular liver, regenerating nodules, and bile staining in the fibrotic planes between the regenerating nodules.

655

Liver

Primary Biliary Cirrhosis

(Left) Hepatic MR of a 43-yearold woman with PBC shows a cirrhotic-appearing liver with a lace-like pattern of fibrosis that surrounds the innumerable regenerative nodules. The fibrotic bands are hypointense on T1WI. (Right) In the same patient, note the widened fissures and disproportionate volume loss of the anterior and medial segments (signs of cirrhosis). The fibrotic bands are hypointense on this unenhanced T1WI.

(Left) The fibrotic bands in the same patient show persistent enhancement on delayed phase, contrastenhanced T1WI, a typical feature of many kinds of fibrous tissue. The lace-like pattern of fibrosis is a characteristic feature of PBC. (Right) More caudal C+ delayed T1WI in the same patient shows the delayed enhancement of the lace-like fibrotic bands . Also seen are widened fissures and a deep gallbladder fossa , features of cirrhosis of various etiologies.

(Left) Fibrotic bands in the same patient are hyperintense on T2WI. (Right) In the same patient, this pattern of lacelike fibrosis surrounding prominent regenerative nodules is very characteristic of primary biliary cirrhosis. The age and gender of the patient are also typical of this disorder.

656

Primary Biliary Cirrhosis Liver

(Left) Axial NECT in a middleaged woman with a several year history of pruritus shows lace-like fibrosis separating innumerable higher density regenerative nodules, all of similar size. Widened fissures and marked volume loss are signs of advanced cirrhosis, which is unusual at the time of initial diagnosis in patients with PBC. (Right) Axial CECT in the same patient shows one of several large varices as another sign of advanced cirrhosis. Most patients with PBC are diagnosed much earlier.

(Left) Axial CECT in a middleaged woman with pruritus due to PBC shows cardiophrenic lymphadenopathy . (Right) Axial CECT in the same patient shows mild widening of the fissures and splenomegaly, the only signs of hepatic disease present. Lymphadenopathy is typically a prominent feature of PBC, as in this patient.

(Left) Axial CECT in a 57-yearold woman with a 7-year history of PBC shows a "cirrhotic morphology" of the liver, with widened fissures and varices in the falciform ligament fissure . A heterogeneous, encapsulated mass that proved to be HCC is also seen. HCC is relatively uncommon in patients with PBC, compared with other causes of cirrhosis. (Right) ERCP shows pruned intrahepatic bile ducts with decreased arborization, the classic "tree in winter" appearance.

657

Liver

Focal Confluent Fibrosis KEY FACTS

IMAGING • Wedge-shaped lesion in anterior and medial segments with volume loss, delayed enhancement, and capsular retraction ○ 90% of cases involve medial segment of left lobe &/or anterior segment of right lobe, with sparing of caudate and lateral segments • Retraction of overlying liver capsule (90%) • Lesions are isoattenuating to adjacent liver parenchyma on venous phase CECT (80%) ○ May show delayed persistent enhancement like other fibrotic liver lesions ○ Does not "wash out" (decrease in enhancement) unlike HCC

CLINICAL ISSUES • Most commonly in cirrhosis secondary to primary sclerosing cholangitis or alcoholism • Can be seen on imaging in ~14% of patients with advanced cirrhosis

TOP DIFFERENTIAL DIAGNOSES

DIAGNOSTIC CHECKLIST

• Cholangiocarcinoma (peripheral) ○ Clinical clues: History of primary sclerosing cholangitis or other chronic bile duct inflammation ○ Dilated bile ducts upstream of tumor

• Review of sequential CT (or MR) over long period of surveillance for cirrhosis will often make diagnosis apparent

(Left) Graphic shows a nodular cirrhotic liver. Fibrosis is prominent, including band-like foci and larger, confluent "masses" with retraction of the overlying liver capsule . (Right) Cut section of an explanted liver shows nodular, cirrhotic morphology and an area of confluent fibrosis, the pale yellow tissue with overlying capsular retraction. The anterior and medial segments are involved disproportionately, with relative sparing of the lateral and caudate segments.

(Left) Axial arterial phase CECT shows minimal enhancement of the lesion but a suggestion of crowded and distorted hepatic arterial branches within. (Right) Axial delayed phase CECT in the same patient shows persistent increased enhancement of the confluent hepatic fibrosis . Note the varices , widened fissures, and splenomegaly as signs of cirrhosis.

658

• Treated malignancies ○ May be indistinguishable from confluent fibrosis ○ Check for prior imaging or clinical evidence of tumor • Hepatic cavernous hemangioma (sclerosed) ○ Especially within cirrhotic liver • Hepatic epithelioid hemangioendothelioma ○ Multiple peripheral, coalescent tumors

Focal Confluent Fibrosis

Synonyms • Confluent hepatic fibrosis

IMAGING CT Findings • NECT ○ Wedge- or band-like area of attenuation – Retraction of overlying liver capsule (90%) ○ Total lobar or segmental involvement – May affect entire segment or lobe, with marked shrinkage ○ In advanced cirrhosis, may simulate total absence of anterior and medial segments • CECT ○ Usually (80%) isodense to parenchyma on portal venous phase – May appear slightly hypo- or hyperdense on portal venous phase – Delayed phase CECT: May show delayed persistent enhancement like other fibrotic liver lesions – Does not "wash out" (decrease in enhancement) unlike HCC ○ Crowding of blood vessels or bile ducts within collapsed area of hepatic parenchyma

MR Findings • T1WI ○ Hypointense to adjacent liver parenchyma • T2WI ○ Lesions are hyperintense due to edema and compressed remnants of portal triads • DWI ○ No restricted diffusion (not bright on DWI) • T1WI C+ ○ Lesions are slightly hypointense to liver on immediate post-gadolinium sequences (80%) – During later dynamic phase, portions of fibrotic lesions may become isointense with liver – Delayed, progressive, increased enhancement on portal venous and equilibrium phase images

DIFFERENTIAL DIAGNOSIS Cholangiocarcinoma (Peripheral) • May cause segmental volume loss, capsular retraction, delayed enhancement ○ Capsular retraction, because these tumors have prominent fibrous stroma and often cause intrahepatic bile duct obstruction • Look for biliary obstruction ○ In confluent fibrosis, unlike in cholangiocarcinoma, bile ducts within affected segments are not dilated ○ In cholangiocarcinoma, dilated ducts upstream of mass

Treated Malignancies

Intrahepatic Biliary Obstruction

Liver

TERMINOLOGY

• Malignant or benign biliary obstruction leads to hepatic atrophy of segments drained by obstructed bile ducts

Hepatic Cavernous Hemangioma • Especially within cirrhotic liver • May become hyalinized, with progressive fibrosis of lesion and volume loss

Hepatic Epithelioid Hemangioendothelioma • Capsular retraction is frequently seen • Multiple peripheral, coalescent tumors ○ Most have "target" appearance

PATHOLOGY General Features • Etiology ○ Any cause of cirrhosis (primary sclerosing cholangitis > alcoholic > chronic viral hepatitis)

Gross Pathologic & Surgical Features • Pale yellow to white mass of fibrous tissue with little hepatic parenchyma

Microscopic Features • Fibrosis with prominent edema with bile duct and lymphocyte proliferation

CLINICAL ISSUES Demographics • Epidemiology ○ Can be seen on imaging in ~14% of patients with advanced cirrhosis who are candidates for liver transplantation ○ Most commonly in cirrhosis secondary to primary sclerosing cholangitis (56%)

Natural History & Prognosis • Progressive volume loss of affected segments

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Characteristic location (medial segment of left lobe, anterior segment of right lobe, or both) and shape (wedgeshaped with capsular retraction and volume loss) enables correct diagnosis and may prevent unnecessary biopsy ○ Review of sequential CT (or MR) over long period of surveillance for cirrhosis will often make diagnosis apparent • Consider cholangiocarcinoma or treated malignancy in differential diagnosis

SELECTED REFERENCES 1. 2.

Galia M et al: Focal lesions in cirrhotic liver: what else beyond hepatocellular carcinoma? Diagn Interv Radiol. Epub ahead of print, 2014 Brancatelli G et al: Focal confluent fibrosis in cirrhotic liver: natural history studied with serial CT. AJR Am J Roentgenol. 192(5):1341-7, 2009

• May be indistinguishable from confluent fibrosis • Check for prior imaging or clinical evidence of tumor

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Liver

Focal Confluent Fibrosis

(Left) Axial NECT shows cirrhotic morphology, ascites, and a hypodense lesion (confluent fibrosis) with overlying capsular retraction and ascites. (Right) Axial NECT in the same patient shows focal confluent fibrosis in the anterior and medial segments with capsular retraction. Note the small medial segment whose left margin is marked by the intersegmental fissure .

(Left) Axial T1WI MR shows a hypointense focus in the anterior and medial segments with overlying capsular retraction. (Right) Axial T2WI MR in the same patient shows hyperintensity of the focal confluent fibrosis . Volume loss and fibrosis are limited to the anterior and medial segments in this patient. Note the ascites in the perihepatic space.

(Left) Axial NECT shows a cirrhotic liver with a nodular contour, ascites, and splenomegaly. There is a broad zone of decreased density and volume loss affecting most of the right lobe of the liver, with retraction of the overlying capsule . (Right) Axial venous CECT in the same patient shows that portions of the right lobe become hyperdense to the remaining liver, an indication of extensive fibrosis. In this patient, almost the entire right lobe is replaced with confluent fibrosis.

660

Focal Confluent Fibrosis Liver

(Left) Axial image in a 60-yearold woman with alcoholic cirrhosis shows a wedgeshaped zone of decreased attenuation on arterialphase CECT. (Right) Delayed phase CECT in the same patient shows delayed, persistent hyperenhancement of the focal confluent fibrosis . Also note the overlying capsular retraction and ascites .

(Left) Axial T2WI MR of a 54year-old man with alcoholic cirrhosis shows cirrhotic morphology with ascites and splenomegaly. Note the wedge-shaped zone of high signal in the anterior and medial segments, representing focal confluent fibrosis. (Right) Axial T2WI in the same patient shows the confluent fibrosis . Volume loss of the affected hepatic segments is evident as displacement of the gallbladder , which lies adjacent to a large recanalized umbilical vein in the intersegmental fissure.

(Left) Axial nonenhanced T1WI MR in the same patient shows the confluent fibrosis as a wedge-shaped zone of hypointensity with retraction of the overlying hepatic capsule. (Right) Axial venous phase contrast-enhanced T1WI MR of the same patient shows minimal enhancement of the fibrotic lesion . The recanalized umbilical vein arises from the intersegmental fissure, marking the left lateral margin of the zone of fibrotic, contracted liver.

661

Liver

Nodular Regenerative Hyperplasia KEY FACTS

TERMINOLOGY • Diffuse micro- or macronodular transformation of hepatic parenchyma without fibrous septa between nodules • Larger focal lesions are called multiacinar (large) regenerative nodules (LRNs) • Benign lesions: No potential for malignant transformation

IMAGING • Diffuse nodular regenerative hyperplasia (NRH) and focal LRNs have different predisposing conditions and different imaging features • Diffuse NRH ○ Associated with other diseases and drugs (e.g., myeloproliferative; immunosuppressives) ○ Signs of portal hypertension are common (> 50%) • LRNs ○ Multiple focal liver masses or nodules 0.5-5 cm in size with persistent enhancement on hepatobiliary-enhanced MR

(Left) Axial CECT in a 52-yearold man with a renal transplant shows massive ascites and esophageal varices . (Right) Axial CT section of the liver in the same patient shows no evidence of fibrosis or focal lesions; liver biopsy showed no cirrhosis, but diffuse nodular regenerative hyperplasia (NRH) was found. This is a recognized cause of liver failure in the absence of cirrhosis and a known complication of solid organ transplantation, among many other etiologies.

(Left) Another CT section in the same renal transplant patient shows widened hepatic fissures , suggestive of cirrhosis. Liver biopsy showed diffuse nodular regenerative hyperplasia. (Right) Trichrome stain highlights the nodules . By definition, there are no fibrous septa between the nodules in nodular regenerative hyperplasia. (Courtesy S. Kakar, MD.)

662

○ Hyperintense on T1WI (75%); iso- to hyperintense on T2WI ○ Hypervascular on arterial, portal venous and delayed phase imaging (no washout) ○ May have central scar ± perinodular "halo" ○ MR with hepatobiliary agents: Uptake and prolonged enhancement – Confirms benign hepatocellular nature of lesions ○ With signs of underlying disease (e.g., Budd-Chiari; thrombosed hepatic veins + IVC) • LRNs: Multiple hypervascular nodules up to 5 cm with persistent delayed enhancement on hepatobiliaryenhanced MR

TOP DIFFERENTIAL DIAGNOSES • Imaging features are more diagnostic than histologic features • Multifocal hepatocellular carcinoma • Focal nodular hyperplasia (multiple)

Nodular Regenerative Hyperplasia

Abbreviations • Nodular regenerative hyperplasia (NRH)

Synonyms • Nodular transformation, noncirrhotic nodulation

Definitions • Uncommonly recognized disorder characterized by diffuse micronodular or macronodular transformation of hepatic parenchyma without fibrous septa between nodules • Larger focal lesions are called multiacinar (large) regenerative nodules (LRNs)

IMAGING General Features • Best diagnostic clue ○ LRNs: Multiple hypervascular nodules up to 5 cm with persistent delayed enhancement on hepatobiliaryenhanced MR • Location ○ Diffuse involvement; microscopic nodules predominantly distributed in periportal region • Size ○ Monoacinar lesions in NRH are only ~ 1 mm in diameter, with clusters of lesions up to 10 mm ○ LRNs are 0.5-5 cm in diameter • Key concepts ○ Diffuse NRH and focal LRNs have different predisposing conditions and different imaging features

CT Findings • NECT ○ Nodules are usually isoattenuating to normal liver ○ Diffuse low attenuation in Budd-Chiari syndrome or steatosis may result in hyperattenuation of nodules • CECT ○ Diffuse nodular regenerative hyperplasia – No focal liver masses; liver may appear normal or dysmorphic – Signs of portal hypertension are common (> 50% of reported cases) □ Splenomegaly, ascites, varices ○ Large regenerative nodules – Multiple focal liver masses or nodules (2 to hundreds) □ Size of nodules: 0.5-5 cm □ Homogeneously hypervascular on arterial and portal venous phase imaging (no washout) □ May have central scar ± perinodular hypo/hyperdense halo □ Along with signs of underlying disease (e.g., for Budd-Chiari = thrombosed hepatic veins and IVC, central hepatic hypertrophy, and peripheral atrophy) □ Signs of portal hypertension in > 50%

MR Findings • T1WI ○ LRNs: Hyperintense (75%) • T2WI

○ Isointense or hypointense nodules; fewer detected ○ May appear hyperintense (due to infarction) ○ Halo sign: Nodule surrounded by peliosis • Multiphasic enhanced MR ○ Bright homogeneous enhancement on arterial and portal venous phase ○ ± ring (halo) enhancement; ± central scar • MR with hepatobiliary contrast (e.g., gadoxetate): Uptake and prolonged enhancement ○ Confirms benign hepatocellular nature of lesions ○ Bright uniform or peripheral enhancement ○ Mimics appearance of focal nodular hyperplasia (FNH) (as does histology)

Liver

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Nodules may appear as hypoechoic (38%), isoechoic (10%), or hyperechoic (53%) lesions • Color Doppler ○ Nodules have prominent arterial supply

Imaging Recommendations • Best imaging tool ○ Multiphasic CT or MR • Protocol advice ○ MR with gadobenate dimeglumine or gadoxetate enhancement – Allows definitive diagnosis of LRNs

DIFFERENTIAL DIAGNOSIS Multifocal Hepatocellular Carcinoma (HCC) • Heterogeneously hyperdense on arterial phase with rapid washout (CT and MR) • Commonly invades portal or hepatic veins; may have capsule • Hypointense on T1WI, hyperintense on T2WI ○ LRNs are hyperintense on T1WI; iso- or hypointense on T2WI • Usually no uptake or retention of hepatobiliary MR contrast agents ○ Heterogeneous retention in some well-differentiated HCC

Focal Nodular Hyperplasia (Multiple) • Imaging and histology may be identical to LRNs • Different clinical setting ○ FNH is usually an isolated lesion in healthy young woman with otherwise normal liver

PATHOLOGY General Features • Etiology ○ Unknown etiology of diffuse NRH; various theories – Hyperplastic response of hepatocytes, probably due to chronic ischemia ○ LRNs are caused by vascular derangement of liver due to decreased portovenous or hepatovenous flow – Explains common occurrence in Budd-Chiari syndrome and patients with portal vein thrombosis

663

Liver

Nodular Regenerative Hyperplasia

–

multifocal hepatic arterial dilatation focal hyperplasia and proliferation of hepatocytes □ Explains FNH-like appearance on imaging and histology ○ No potential for malignant transformation of diffuse or focal lesions • Associated abnormalities ○ Diffuse NRH: Many associated diseases – Solid organ and bone marrow transplantation – Myeloproliferative disorders (e.g., polycythemia, lymphoma, myeloma) – Chemotherapy – Autoimmune diseases (e.g., systemic lupus, rheumatoid, polyarteritis) – Heart disease or constrictive pericarditis – Familial occurrence (rare) – Old age: Found in 5% of elderly ○ Large regenerative nodules – Budd-Chiari syndrome (accounts for > 70% of cases) – Heart disease (especially congenital) – Portal vein thrombosis (chronic) – Cirrhosis of various etiologies, especially autoimmune hepatitis

Microscopic Features • Diffuse NRH: Monoacinar lesions present in liver that is neither fibrotic nor cirrhotic • LRNs: Multiacinar nodules, consist of different-sized hepatocytes 1-2 plates wide and narrow sinusoids organized to form large regenerative nodules ○ Between nodules are areas of centrilobular atrophy with curvilinear areas of sinusoidal dilation, marked congestion, and paucity of fibrosis ○ May have central scar; indistinguishable from FNH ○ ± proliferation of bile ductules or metaplastic transformation of hepatocytes into bile ductules ○ ± mineral deposits and copper accumulation in nodules • Both forms of disease have obliteration of small hepatic veins ± portal veins ○ Leads to ischemic atrophy with secondary hyperplastic response in areas of favorable blood flow ○ Relatively mild and diffuse ischemia diffuse form of NRH

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Usually asymptomatic but may cause noncirrhotic portal hypertension (varices, etc.) • Other signs/symptoms ○ Relate to underlying disease (e.g., Budd-Chiari, heart disease, autoimmune disease) • Diagnosis: Liver biopsy of LRNs shows hyperplastic liver tissue, ± inflammation, scar (similar to FNH) ○ Pathologist is less able to make distinction than radiologist with knowledge of imaging and clinical features in individual cases – Histologically, especially on fine-needle aspiration, difficult to distinguish from FNH, adenoma, or even HCC 664

Demographics • Age ○ More common in adults, increases with age • Gender ○ No predilection • Epidemiology ○ Uncommonly recognized but certainly not rare ○ Probably underdiagnosed owing to lack of recognition of entity and limited sampling by biopsy

Natural History & Prognosis • LRNs may increase in size; rarely infarct ○ Do not evolve into HCC • Diffuse NRH usually remains asymptomatic ○ May cause progressive portal hypertension (e.g., variceal hemorrhage), rarely liver failure • Symptoms of both disorders are usually due to underlying conditions • Prognosis is related to consequences of portal hypertension and severity of associated diseases

Treatment • Management directed to portal hypertension and variceal bleeding • Orthotopic liver transplantation for progressive hepatic failure and clinical end-stage liver disease

DIAGNOSTIC CHECKLIST Consider • Diffuse NRH may cause variceal bleeding in absence of cirrhosis • LRNs in dysmorphic liver are easily confused with other masses, such as HCC ○ Important to recognize underlying liver disorder (e.g., Budd-Chiari) and characteristic appearance of LRNs

Image Interpretation Pearls • LRNs: Imaging and path appearance almost identical to FNH • Multiple focal hypervascular masses without washout in Budd-Chiari patient = LRNs, not HCC

SELECTED REFERENCES 1.

2.

3.

4.

5.

Choe H et al: Nodular regenerative hyperplasia causing portal hypertension in a patient with chronic graft versus host disease: response to sirolimus. Acta Haematol. 132(1):49-52, 2014 Morris-Stiff G et al: Nodular regenerative hyperplasia (NRH) complicating oxaliplatin chemotherapy in patients undergoing resection of colorectal liver metastases. Eur J Surg Oncol. 40(8):1016-20, 2014 Caturelli E et al: Nodular regenerative hyperplasia of the liver: coral atoll-like lesions on ultrasound are characteristic in predisposed patients. Br J Radiol. 84(1003):e129-34, 2011 Hartleb M et al: Nodular regenerative hyperplasia: evolving concepts on underdiagnosed cause of portal hypertension. World J Gastroenterol. 17(11):1400-9, 2011 Brancatelli G et al: Large regenerative nodules in Budd-Chiari syndrome and other vascular disorders of the liver: CT and MR imaging findings with clinicopathologic correlation. AJR Am J Roentgenol. 178(4):877-83, 2002

Nodular Regenerative Hyperplasia Liver

(Left) T1WI MR in a 63-yearold man with a myeloproliferative disorder shows marked splenomegaly, likely due to extramedullary hematopoiesis. The liver shows no apparent diffuse or focal abnormality, but biopsy revealed diffuse nodular regenerative hyperplasia, a known complication of myelodysplasia and the medications used to treat it. (Right) T1WI MR in the same patient again shows no apparent hepatic lesion in this case of biopsy-proven nodular regenerative hyperplasia.

(Left) Axial T1WI C+ MR shows numerous 2 cm hyperintense lesions in a patient with BuddChiari syndrome. Note the hypointense "halo" around some of these large regenerative nodules (LRNs) , a characteristic but not common feature. (Right) Axial T2WI MR in the same patient demonstrates fewer and much less evident hypointense foci of the focal multiacinar form of nodular regenerative hyperplasia in the right hepatic lobe.

(Left) Gross pathology section of an explanted dysmorphic liver from a patient with BuddChiari syndrome shows caudate hypertrophy , lateral segment atrophy, and multiple orange, discolored LRNs . (Right) Axial CECT in a man with chronic BuddChiari syndrome shows multiple hypervascular LRNs , the macroscopic form of nodular regenerative hyperplasia.

665

Liver

Nodular Regenerative Hyperplasia

(Left) Axial CECT shows one of several hypervascular nodules with hypodense rims or "halos" . Biopsy revealed hyperplastic benign liver tissue consistent with large (multiacinar) regenerative nodules. (Right) CECT in the same patient shows chronic occlusion and cavernous transformation of the portal vein . Large (multiacinar) regenerative nodules occur almost exclusively in liver that has some chronic vascular insufficiency, such as portal vein thrombosis or Budd-Chiari syndrome.

(Left) The arterial phase of a contrast-enhanced T1WI MR shows multiple hypervascular foci. Some of the lesions seem to have a hypointense rim , whereas others have a hypointense central scar , findings that can be seen with focal nodular hyperplasia (FNH). (Right) Delayed MR scan in the same patient after IV administration of gadobenate dimeglumine shows persistent uptake and retention of the agent within the nodules, indicating functional hepatocytes and a benign etiology.

(Left) Axial T1WI MR in a 43year-old woman with BuddChiari syndrome and multiple LRNs shows multiple hypervascular nodules, at least 1 of which has a central scar . (Right) Photograph of the resected nodule in the same case shows the LRN as well as a fibrous scar , findings that are usually associated with FNH, which may have almost identical imaging and histologic features.

666

Nodular Regenerative Hyperplasia Liver

(Left) Axial CECT shows classic findings of Budd-Chiari and multiacinar LRNs. Note the IVC stent , an occluded right hepatic vein , and innumerable LRNs that are persistently hyperdense on this portal venous phase image. (Right) This photomicrograph shows a resected LRN that has a reticulin stain (in green) that highlights the peripheral and central "scar" that is seen in some LRNs, very similar to that found in FNH.

(Left) Arterial-phase CECT in a 35-year-old man with BuddChiari syndrome shows multiple enhancing LRNs, including some with peripheral "halos" and others with central "scars" . (Right) Additional LRNs are noted on this CECT section from the same patient. Note the extrahepatic venous graft .

(Left) Axial CECT in the same patient following IVC stent placement shows the IVC stent . There was an overall decrease in the size and number of LRNs following stent placement. (Right) An additional CECT section from the same patient shows fewer and smaller LRNs following placement of the IVC stent .

667

Liver

Regenerative and Dysplastic Nodules KEY FACTS

TERMINOLOGY • Localized proliferation of liver parenchyma within cirrhotic liver in response to liver injury ○ May progress to become dysplastic or malignant

IMAGING • Regenerative nodules (RNs): Multiple nodules in cirrhotic liver with decreased signal intensity on T2WI or GRE ○ Commonly < 2 cm, usually not seen on CECT or T1WI MR ○ Hyperattenuating to liver on NECT; hypointense on T2WI + GRE; take up and retain gadoxetate (Eovist) • Dysplastic nodules (DNs): Fewer, larger, hyperintense on T1WI and hypointense on T2WI ○ Usually 2-4 cm in diameter ○ Should not be hypervascular (raises concern for hepatocellular carcinoma [HCC]) ○ High-grade DNs and HCC lack functioning hepatocytes and biliary excretion; no uptake of hepatobiliary MR contrast agents

(Left) This cirrhotic nodule has an irregular extension of hepatocytes into the fibrous septum with associated inflammation, mimicking stromal invasion. (Courtesy S. Kakar, MD.) (Right) T2WI MR shows innumerable subcentimeter hypointense nodules that are typical of cirrhotic regenerative nodules. MR sequences that best show regenerative nodules are the T2WI and GRE series.

(Left) Axial NECT in a 54-yearold woman with primary biliary cirrhosis shows innumerable small, hyperdense, regenerative nodules , surrounded by lace-like fibrosis. (Right) Axial CECT in the same patient demonstrates that the nodules disappear into the background cirrhotic liver, owing to minimal enhancement of the nodules and persistent enhancement of the fibrotic bands. Also noted is prominent porta hepatis lymphadenopathy , another typical feature of primary biliary cirrhosis.

668

○ RNs and low-grade DNs show no restricted diffusion (= not bright) on DWI

TOP DIFFERENTIAL DIAGNOSES • Hepatocellular carcinoma ○ Heterogeneously hypervascular on arterial phase with washout ± capsule ○ Variably hypointense on T1WI; hyperintense on T2WI; bright on DWI ○ Usually no uptake or retention of gadoxetate (Eovist) • Nodular regenerative hyperplasia ○ Focal form = "large regenerative nodules" ○ Distinct pathologic entity, associated with Budd-Chiari syndrome

DIAGNOSTIC CHECKLIST • MR allows better differentiation among focal lesions in cirrhotic liver than CT

Regenerative and Dysplastic Nodules

Abbreviations

MR Findings

• Dysplastic nodule (DN) • Regenerative nodule (RN)

Synonyms • Cirrhotic nodule

Definitions • Localized proliferation of liver parenchyma within cirrhotic liver in response to liver injury ○ May progress to become dysplastic or even malignant

IMAGING General Features • Best diagnostic clue ○ RNs: Multiple small nodules in cirrhotic liver with intensity on T2WI or GRE ○ DNs: Fewer, larger, hyperintense on T1WI and hypointense on T2WI • Location ○ Evenly scattered throughout liver • Size ○ RNs are commonly < 2 cm – DNs usually 2-4 cm in diameter • Morphology ○ RNs: Innumerable – DNs: Single or few ○ Round, well circumscribed

Liver

– Hypervascularity raises concern for development of HCC

TERMINOLOGY

signal

Imaging Recommendations • Best imaging tool ○ MR • Protocol advice ○ Need T1WI and T2WI, plus contrast-enhanced T1WI to evaluate vascularity ○ Gadoxetate (Eovist, Primovist) or gadobenate dimeglumine helps to distinguish among nodules – Expect uptake and retention on delayed phase imaging for RNs and DNs – No uptake or retention within hepatocellular carcinoma (HCC) nodules □ High-grade DNs may also show no uptake or retention □ Some HCC show patchy uptake and retention

CT Findings • NECT ○ Most RNs are not evident on CT or T1WI MR ○ Small nodules: Isoattenuating (undetected) ○ RNs: May be seen on NECT as hyperattenuating to surrounding liver – Due to increased iron or glycogen content – Or surrounding "halo" of low-attenuation fibrosis • CECT ○ RNs: Enhance slightly less than liver – Results in disappearance of RNs on CECT ○ DNs: Iso- to hyperattenuating in arterial phase – Most are not hypervascular

• T1WI ○ RNs – Variable signal intensity – Usually isointense to liver (undetected) ○ DNs – Variable signal intensity – Usually iso- to hyperintense to liver • T2WI ○ RNs – signal intensity compared to liver (due to iron content) ○ DNs – Low-grade nodules tend to have lower signal intensity compared to liver – High-grade nodules tend to have slightly higher signal intensity compared to liver □ signal intensity corresponds to dedifferentiation and concern for HCC • T2* GRE ○ RNs: signal intensity compared to liver – "Blooming" (appearing larger) due to susceptibility effect of iron • DWI ○ RNs and low-grade DNs show no restricted diffusion (= not bright) on DWI ○ High-grade DNs and HCC are usually bright on DWI • T1WI C+ ○ RNs – Isointense to liver (undetected) or slightly hypointense ○ DNs – Variably hyperintense to adjacent liver □ Increasing vascularity increases concern for malignant degeneration of DN • MR with gadobenate dimeglumine or gadoxetate: Avid uptake and retention in RNs and DNs ○ Indicates functioning hepatocytes ○ Favors benign etiology (RN) – High-grade DNs and HCC lack functioning hepatocytes and biliary excretion □ no uptake (hypointense on delayed imaging)

Ultrasonographic Findings • Nodules may appear as hypo-, iso-, or hyperechoic ○ Most RNs and DNs are not apparent on US

DIFFERENTIAL DIAGNOSIS Hepatocellular Carcinoma • Hypoattenuating to liver on NECT and delayed CECT • Heterogeneously hypervascular on arterial phase with washout on venous or delayed phase is strongly indicative of HCC • Variably hypointense on T1WI; hyperintense on T2WI; bright on DWI • Size usually > 20 mm • Other characteristics: Heterogeneity, multiplicity, encapsulation, venous invasion 669

Liver

Regenerative and Dysplastic Nodules

• Diffuse micronodular transformation of hepatic parenchyma without fibrous septa between nodules • Seen in noncirrhotic liver • Focal form = "large regenerative nodules" ○ Distinct pathologic entity, not merely larger-than-usual cirrhotic RN ○ Associated with Budd-Chiari syndrome > congenital heart disease > other conditions • Usually hyperintense on T1WI and iso- to hypointense on T2WI • ± ring or "halo" enhancement on enhanced MR • Bright enhancement on arterial phase that persists on venous phase CECT or MR • Usually multiple; 1.5-5 cm in size

PATHOLOGY General Features • Associated abnormalities ○ Liver cirrhosis • RNs are benign, but some progress to become dysplastic • High-grade DNs are premalignant, but rate of transformation is slow

CLINICAL ISSUES Presentation • Other signs/symptoms ○ Those related to cirrhosis and portal hypertension – Abdominal distention, jaundice, ascites, varices, etc.

Demographics • Age ○ Adults • Gender ○ No gender predilection known – Alcoholic cirrhosis more common in men

Natural History & Prognosis • Transformation rate of DNs to HCC is relatively low • DNs should not be treated or managed as cancers • As size increases, likelihood of high-grade dysplasia or malignancy increases ○ High-grade dysplasia is very unlikely in lesions < 2 cm in size

DIAGNOSTIC CHECKLIST

Staging, Grading, & Classification

Image Interpretation Pearls

• RNs are further classified to micronodules (< 3 mm) and macronodules ( 3 mm) • Dysplastic lesions are classified as low or high grade based on degree of dysplasia

• MR is best imaging modality, especially with hepatobiliary contrast media (e.g., gadoxetate [Eovist or Primovist]) ○ Imaging allows confident diagnosis of lesions > ~ 3 cm

Gross Pathologic & Surgical Features • RNs ○ Have normal hepatocellular function and Kupffer cell density ○ Round, well circumscribed; most nodules < 2 cm ○ Numerous, diffusely distributed throughout liver • DNs ○ High-grade nodules have predominantly arterial perfusion secondary to angiogenesis ○ As dedifferentiation proceeds, hepatocellular function and Kupffer cell density decrease • RNs and low-grade DNs are predominantly perfused by portal system • Absence of intralesional necrosis, hemorrhage, local invasion

Microscopic Features • Localized proliferation of hepatocytes and supporting stroma surrounded by fibrous septa • Differentiation of DNs from RN may be difficult, even at microscopic level • RNs ○ Normal vasculature, intact reticulin framework ○ Preserved hepatocellular architecture ○ Absent mitotic activity ○ binucleate or multinucleate hepatocytes • DNs ○ Architectural derangement ○ Atypia, nuclear crowding ○ Low-grade DNs resemble RNs and may be difficult to distinguish 670

○ High-grade DNs resemble well-differentiated HCC

Nodular Regenerative Hyperplasia

Reporting Tips • Characterize appearance of focal nodules in cirrhotic liver by density or intensity on all phases of imaging ○ Assess vascularity and washout

SELECTED REFERENCES 1. 2. 3.

4.

5.

6. 7. 8.

9.

Rich N et al: Hepatocellular carcinoma tumour markers: current role and expectations. Best Pract Res Clin Gastroenterol. 28(5):843-53, 2014 Ronot M et al: Hepatocellular carcinoma: diagnostic criteria by imaging techniques. Best Pract Res Clin Gastroenterol. 28(5):795-812, 2014 Bartolozzi C et al: Contrast-enhanced magnetic resonance imaging of 102 nodules in cirrhosis: correlation with histological findings on explanted livers. Abdom Imaging. 38(2):290-6, 2013 Quaia E et al: Predictors of dysplastic nodule diagnosis in patients with liver cirrhosis on unenhanced and gadobenate dimeglumine-enhanced MRI with dynamic and hepatobiliary phase. AJR Am J Roentgenol. 200(3):553-62, 2013 Giorgio A et al: Characterization of dysplastic nodules, early hepatocellular carcinoma and progressed hepatocellular carcinoma in cirrhosis with contrast-enhanced ultrasound. Anticancer Res. 31(11):3977-82, 2011 Lee JM et al: Hepatocellular nodules in liver cirrhosis: MR evaluation. Abdom Imaging. 36(3):282-9, 2011 Ouedraogo NA et al: Dysplastic hepatic nodules: radiological abnormalities and histopathological correlations. Eur J Radiol. 79(2):232-6, 2011 Chou CT et al: Characterization of cirrhotic nodules with gadoxetic acidenhanced magnetic resonance imaging: the efficacy of hepatocyte-phase imaging. J Magn Reson Imaging. 32(4):895-902, 2010 Hanna RF et al: Cirrhosis-associated hepatocellular nodules: correlation of histopathologic and MR imaging features. Radiographics. 28(3):747-69, 2008

Regenerative and Dysplastic Nodules Liver

(Left) In this 50-year-old man with cirrhosis, there is a welldefined spherical mass that is hyperintense on T1WI and showed no signal loss on opposed-phase T1WI GRE (not shown). (Right) In the same patient, the lesion is hypointense on T2WI, typical of a dysplastic nodule and atypical for hepatocellular carcinoma (HCC).

(Left) Late arterial phase contrast-enhanced T1WI of the same patient shows minimal vascularity or enhancement of the lesion . (Right) Venous phase T1WI MR in the same patient shows the lesion (dysplastic nodule) as hypointense to the background liver, more likely due to increased enhancement of the background liver than washout of contrast from the lesion.

(Left) The lesion is hypoechoic on US, which was used to guide the biopsy in the same patient. While the MR imaging features are characteristic of a dysplastic nodule, it was judged important to confirm on a USguided biopsy, which showed dysplasia without evidence of HCC. (Right) High-grade dysplastic nodule contains an unpaired arteriole . Bile ductular reaction is seen within and at the periphery . (Courtesy S. Kakar, MD.)

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Liver

Regenerative and Dysplastic Nodules

(Left) Axial contrast-enhanced T1WI MR in a 61-year-old woman with cirrhosis shows a nodular liver with widened fissures, typical for cirrhosis. There are innumerable small, hypointense, cirrhotic regenerative nodules, but they are not very evident. (Right) Axial T2WI MR in the same patient shows the cirrhotic nodules more clearly, as subcentimeter, hypointense lesions , a characteristic appearance of benign regenerative nodules.

(Left) Axial T1WI MR in the same patient shows a welldefined hyperintense lesion in the lateral segment that proved to be a dysplastic nodule . (Right) Another axial T1WI MR in the same patient shows a hypointense lesion in segment 6 that proved to be an HCC .

(Left) Axial T2WI MR in the same patient shows the dysplastic nodule to be relatively hypointense, a characteristic appearance of a dysplastic lesion. (Right) Another axial T2WI MR in the same patient shows the HCC to be relatively hyperintense, a typical feature of a malignant nodule or mass.

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Regenerative and Dysplastic Nodules Liver

(Left) Axial contrast-enhanced T1WI MR in the arterial phase shows minimal enhancement of the dysplastic nodule , a characteristic appearance of this lesion. (Right) Another contrast-enhanced T1WI MR in the arterial phase in the same patient shows heterogeneous hypervascular enhancement of the HCC , a typical appearance of this lesion.

(Left) Axial delayed (hepatobiliary) phase T1WI MR in the same patient shows enhancement and retention of the contrast medium (gadoxetate [Eovist]) by the dysplastic nodule and within many of the regenerative nodules . (Right) Another axial delayed phase T1WI MR in the same patient shows no retention of contrast within the HCC .

(Left) Axial diffusion-weighted image in the same patient shows no restricted diffusion (bright signal) within the dysplastic nodule . (Right) Another axial diffusionweighted image in the same patient shows restricted diffusion (bright signal) within the HCC , a characteristic feature of malignant masses.

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Liver

Regenerative and Dysplastic Nodules

(Left) Axial NECT in a 78-yearold woman with chronic hepatitis C shows a mass in the lateral segment that has 2 distinct components, including a fat density left 1/2 and a soft tissue density right 1/2 . (Right) Axial fatsuppressed T1WI MR in the same patient shows relatively bright signal within the right component of the nodule , which is typical of a dysplastic nodule. The right component shows signal suppression typical of a fat-containing lesion , which is suggestive of HCC.

(Left) Axial T2WI MR in the same patient shows low signal within the dysplastic nodule and bright signal within the HCC . This is an example of the nodule-in-nodule pattern of HCC within a dysplastic nodule. (Right) Axial GRE opposed-phase MR in the same patient shows signal suppression from the fatcontaining HCC and inherent low intensity within the dysplastic nodule .

(Left) This hepatocellular nodule has features of highgrade dysplasia, but the infiltration of the nonneoplastic liver parenchyma at the periphery indicates that this is an early HCC. Stromal invasion is key in distinguishing early HCC from high-grade dysplastic nodules. (Courtesy S. Kakar, MD.) (Right) This hepatocellular nodule with high-grade dysplastic features shows infiltration of a portal tract and fibrous septa at the periphery, supporting a diagnosis of early HCC. (Courtesy S. Kakar, MD.)

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Regenerative and Dysplastic Nodules Liver

(Left) Arterial phase axial CT in a 50-year-old man with cirrhosis shows a nodule in the right hepatic lobe with foci of hypervascular enhancement . (Right) Venous phase CT in the same patient shows no definite washout from the lesion, but does show the presence of a capsule , which is suggestive of HCC in this setting. The liver has a cirrhotic morphology and splenomegaly, and varices are noted.

(Left) Axial T1WI MR in the same patient shows a nodulein-nodule pattern, with a hypointense-appearing right 1/2 (HCC) and a hyperintense left 1/2 of the lesion that is typical for a dysplastic nodule. (Right) Axial T2WI MR in the same patient shows that the right 1/2 of the nodule is hyperintense, typical of an HCC , whereas the left 1/2 is hypointense, typical of a dysplastic nodule . This is the nodule-in-nodule pattern of an HCC developing within or from a dysplastic nodule.

(Left) Arterial phase contrastenhanced T1WI MR in the same patient shows hypervascular enhancement of the HCC portion and minimal enhancement of the dysplastic portion of the nodule. (Right) Delayed contrast-enhanced MR in the same patient shows contrast washout and a partial capsule around the mass , characteristic features of HCC that would be rare for a simple cirrhotic regenerative or dysplastic nodule. HCC within a dysplastic nodule was confirmed at resection.

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Liver

Solitary Necrotic Nodule KEY FACTS

TERMINOLOGY • Benign hepatic lesion with completely necrotic core surrounded by dense hyalinized fibrous capsule

IMAGING • Bull's-eye solitary lesion on ultrasound • Hypoattenuating compared to liver parenchyma on NECT ○ No enhancement on CECT ○ Calcification may be seen • MR characteristics are secondary to low cellularity, vascularity, and water content of lesion ○ Low signal intensity on all sequences (T1WI and T2WI) with no contrast enhancement ○ May see small central focus of increased signal intensity ○ Low signal intensity on DWI

TOP DIFFERENTIAL DIAGNOSES • Almost all other lesions have some enhancement and varying appearance on MR sequences

(Left) Axial T1WI MR shows a small, hypointense mass in the subcapsular region of the right lobe. (Right) In the same patient, the mass is seen as hypointense on T2WI, except for a small, central, mildly hyperintense focus. Most neoplastic hepatic masses are hyperintense on T2WI, a helpful distinction from solitary necrotic nodule.

(Left) In the same patient, the histologically confirmed solitary necrotic nodule shows no enhancement on axial T1WI MR in the portal venous phase of enhancement. (Right) Axial CECT shows a small nonenhancing lesion that had the typical appearance of a cavernous hemangioma on an MR study performed several years earlier. Hyalinization or sclerosis of hemangioma is considered to be the etiology of at least some solitary necrotic nodules.

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○ ○ ○ ○

Cholangiocarcinoma (peripheral) Hepatic metastases and lymphoma Regenerative and dysplastic nodules Inflammatory hepatic pseudotumor

PATHOLOGY • Completely necrotic core and hyalinized fibrous capsule containing elastic fibers • Probably represents thrombosed or hyalinized cavernous hemangioma

CLINICAL ISSUES • Considered rare, but may actually be more common ○ Some hypodense or hypointense liver lesions considered "too small to characterize" are probably hyalinized hemangiomas • Affects all age groups • Constitutes 0.2% of liver masses

Peribiliary Cysts

TERMINOLOGY • Cystic dilation of obstructed periductal glands of bile ducts

IMAGING • Well-defined, water-attenuation/-intensity, round, oval, or tubular structures adjacent to hilar bile ducts ○ "String of pearls" or "grapes on a stem" are common appearances • Usually multiple ○ Discrete, linear, or confluent configuration • Size is variable, up to 2.5 cm • Smooth and thin walls; no internal structures • No enhancement of contents on CECT or MR • Do not communicate with biliary tree (e.g., on ERCP)

TOP DIFFERENTIAL DIAGNOSES • Dilated, obstructed bile ducts ○ Intrahepatic bile ducts rarely dilate much in cirrhosis • Periportal edema/inflammation

• Caroli disease • Hepatic autosomal dominant (AD) polycystic disease • Intrahepatic bile ducts rarely dilate much in cirrhotic liver

Liver

KEY FACTS

PATHOLOGY • Disturbed portal circulation &/or inflammation occlusion of neck of peribiliary glands cyst formation • Associated with ○ Cirrhosis, portal hypertension, portal vein thrombosis ○ Hepatic AD polycystic disease ○ Caroli disease

CLINICAL ISSUES • Asymptomatic from cysts ○ Symptoms relate to underlying liver disease • Size and number of cysts tend to increase as cirrhosis progresses • Especially common in alcoholic liver disease

(Left) Axial T2WI FS MR in a 45-year-old woman with cirrhosis shows evidence of a small cirrhotic liver and portal hypertension with ascites . Note the water-intensity lesions in the portal triads that simulate dilated bile ducts. However, these do not arborize like bile ducts and are spherical in shape, representing peribiliary cysts. (Right) Axial CECT in the same patient shows the "string of pearls" appearance of peribiliary cysts in the bile duct walls along the portal triads .

(Left) Sonography in a 64-yearold man with cirrhosis shows multiple sonolucent cystic structures adjacent to the portal and hepatic vessels. (Right) Axial T2WI MR of peribiliary cysts in an otherwise normal liver shows high-intensity fluid content of the cysts , which have the appearance of grapes on a stem and follow the general distribution of the bile ducts. Peribiliary cysts rarely occur in noncirrhotic livers.

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Liver

Glycogen Storage Disease KEY FACTS

TERMINOLOGY • Group of disease states characterized by inborn errors of glucose and glycogen metabolism

IMAGING • Best clue: Hepatomegaly and multiple hepatic adenomas in a chronically ill young patient • Hepatic attenuation increased due to glycogen ○ Or due to steatosis • Hepatic adenomas occur in > 50% of patients with glycogen storage disease (GSD) Ia (von Gierke), 25% of GSD III ○ Adenomas are often multiple in this setting ○ Often occur before age 20 • Hepatocellular carcinoma (HCC) ○ Less common complication of GSD Ia and III

TOP DIFFERENTIAL DIAGNOSES • Hemochromatosis

(Left) CECT in the hepatic arterial phase of a 36-year-old woman with glycogen storage disease (GSD) type I shows a hypervascular mass with a focal calcification and a hypodense capsule, representing an hepatic adenoma. The liver is mildly enlarged and of slightly increased density, which is more evident on NECT (not shown). (Right) Axial contrastenhanced T1WI MR in the same patient shows the same hypervascular mass . Hepatomegaly is present, but no specific signs of GSD were recognized on imaging.

(Left) The mosaic pattern results from swollen hepatocytes compressing the sinusoids in this case of GSD Ia. The cell membranes are accentuated, and prominent glycogenated nuclei are seen. (Courtesy G. Kim, MD.) (Right) Reticulin stain shows the abnormal architecture, loss of reticulin fibers , and pseudorosette formation in this hepatocellular carcinoma (HCC) arising in a patient with GSD Ia. Both adenomas and HCC are more prevalent in patients with certain GSDs, especially types I and III. (Courtesy G. Kim, MD.)

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○ Much more common cause of increased density in liver (on CT) • Steatosis (fatty liver) ○ This and other causes are much more common than GSD

PATHOLOGY • Caused by mutation of genes responsible for proteins involved in glycogen synthesis, degradation (glycogenosis), or regulation • Associated diseases: Inflammatory bowel disease (in GSD Ib); renal calculi (very common) • Diagnosis by liver biopsy and DNA mutation analysis

CLINICAL ISSUES • Treatment: Maintenance of near normal blood glucose levels by careful manipulation of diet • Liver transplantation in selected cases ○ Especially for GSD I with adenomatosis or HCC

Glycogen Storage Disease

Abbreviations • Glycogen storage disease (GSD)

Definitions • Group of disease states characterized by inborn errors of glucose and glycogen metabolism

IMAGING General Features • Best diagnostic clue ○ Hepatomegaly and multiple hepatic adenomas in a chronically ill young patient ○ Hepatomegaly in most affected patients – Liver may be normal size ○ Liver may be of increased or decreased density – Increased due to predominance of glycogen □ GSD 0 decreased hepatic glycogen □ Others GSD types result in hepatic glycogen – Decreased if steatosis predominates ○ Hepatic adenoma – Adenomas are associated with GSD types I and III □ Incidence: > 50% in patients with GSD I (von Gierke disease); 25% in GSD III □ Often multiple; more frequent in males □ Often occur before age 20 □ Appearance: Hypervascular, encapsulated, lipidcontaining, ± focal calcification – Hepatocellular carcinoma (HCC) □ Less common complication of GSD Ia and III

Imaging Recommendations • Best imaging tool ○ MR to detect and characterize hepatic mass (adenoma or HCC)

DIFFERENTIAL DIAGNOSIS Hemochromatosis • Much more common cause of increased density in liver (on CT)

Steatosis (Fatty Liver) • Steatosis of many causes is much more common than GSDs ○ e.g., alcoholic and nonalcoholic steatohepatitis

PATHOLOGY General Features • Etiology ○ Inborn error of glucose and glycogen metabolism • Genetics ○ Caused by mutation of genes responsible for proteins involved in glycogen synthesis, degradation (glycogenosis), or regulation ○ Most GSDs are inherited as autosomal recessive traits • Associated abnormalities ○ Inflammatory bowel disease in GSD Ib ○ Nephrolithiasis is very common

Staging, Grading, & Classification

Liver

TERMINOLOGY

• At least 15 types of GSDs have been identified ○ 80% of hepatic GSDs are types I, III, and IX

Gross Pathologic & Surgical Features • Pale, swollen liver

Microscopic Features • Pale-staining, swollen hepatocytes • Excess glycogen, variable fibrosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Symptoms of hypoglycemia (feeling weak, faint) – Ketoacidosis, seizures – Symptoms improve with eating ○ Muscle symptoms – Muscle is 2nd largest storage of glycogen (after liver) □ Muscle pain, cramps, exercise intolerance, progressive weakness, myoglobinuria • Other signs/symptoms ○ Growth retardation, failure to thrive, recurrent infections, delayed psychomotor development ○ Age at onset from in utero to adulthood

Demographics • Epidemiology ○ Incidence of specific GSDs is variable among populations, by ethnicity and other factors

SELECTED REFERENCES 1.

De Kock I et al: Hepatic adenomatosis: MR imaging features. JBR-BTR. 97(2):105-8, 2014 2. Bhattacharya K: Dietary dilemmas in the management of glycogen storage disease type I. J Inherit Metab Dis. 34(3):621-9, 2011 3. Luo X et al: Hepatorenal correction in murine glycogen storage disease type I with a double-stranded adeno-associated virus vector. Mol Ther. 19(11):1961-70, 2011 4. Manzia TM et al: Glycogen storage disease type Ia and VI associated with hepatocellular carcinoma: two case reports. Transplant Proc. 43(4):1181-3, 2011 5. Marega A et al: Preemptive liver-kidney transplantation in von Gierke disease: a case report. Transplant Proc. 43(4):1196-7, 2011 6. Ochi H et al: Abdominal imaging findings of a patient with hepatocellular carcinoma associated with glycogen storage disease type 1a. Intern Med. 50(20):2317-22, 2011 7. Wang DQ et al: Natural history of hepatocellular adenoma formation in glycogen storage disease type I. J Pediatr. 159(3):442-6, 2011 8. Cassiman D et al: An adult male patient with multiple adenomas and a hepatocellular carcinoma: mild glycogen storage disease type Ia. J Hepatol. 53(1):213-7, 2010 9. Chou JY et al: Glycogen storage disease type I and G6Pase- deficiency: etiology and therapy. Nat Rev Endocrinol. 6(12):676-88, 2010 10. Das AM et al: Glycogen storage disease type 1: impact of medium-chain triglycerides on metabolic control and growth. Ann Nutr Metab. 56(3):22532, 2010 11. Dragani TA: Risk of HCC: genetic heterogeneity and complex genetics. J Hepatol. 52(2):252-7, 2010 12. Scales CD Jr et al: Stone forming risk factors in patients with type Ia glycogen storage disease. J Urol. 183(3):1022-5, 2010

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Liver

Hemochromatosis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Iron overload disorder in which there is structural and functional impairment of involved organs • Hemochromatosis: Classified into 2 types ○ Primary (hereditary): Autosomal recessive ○ Secondary: Due to increased iron intake, transfusions, etc. • Hemosiderosis ○ Increased iron deposition without organ damage

• Amiodarone therapy • Glycogen storage disease

IMAGING • Liver that is hyperdense on NECT and markedly hypointense on T2WI or in-phase GRE MR • Primary (hereditary) hemochromatosis ○ Affects parenchymal cells of liver, pancreas, and heart • Secondary hemochromatosis ○ Affects RES: Liver, spleen, nodes

(Left) In this case of primary (hereditary) hemochromatosis, coarse and refractile iron are readily granules discernible within the hepatocytes and bile duct epithelium. (Courtesy M. Yeh, MD, PhD.) (Right) The iron deposition is confirmed by a Perl iron stain. (Courtesy M. Yeh, MD, PhD.)

(Left) Axial T2WI MR shows marked hypointensity throughout the liver in this patient with primary (hereditary) hemochromatosis. Note the normal intensity of the spleen by comparison. (Right) In this patient with secondary hemochromatosis due to blood transfusions, axial NECT shows marked diffuse increased density in the liver. The spleen is surgically absent.

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PATHOLOGY • Primary (hereditary) hemochromatosis ○ Relatively common and underdiagnosed cause of liver disease ○ Affects 1 in 220 of some European groups ○ Clinical: Cirrhosis and "bronze diabetes" ○ Progressive injury of heart, liver, and pancreas ○ Increased risk of hepatocellular carcinoma

DIAGNOSTIC CHECKLIST • T2WI: Marked signal loss of liver in primary type and marked signal loss of both liver and spleen in secondary type of hemochromatosis • Due to phlebotomy or chelation, liver may appear as normal attenuation on CT

Hemochromatosis

Definitions • Iron overload disorder in which there is structural and functional impairment of involved organs • Hemosiderosis ○ Increased iron deposition without organ damage

IMAGING General Features • Best diagnostic clue ○ Liver that is hyperdense on NECT and markedly hypointense on T2WI or in-phase GRE MR • Key concepts ○ Hemochromatosis: Classified into 2 types – Primary (hereditary) □ Autosomal recessive disorder causing increased absorption of iron from gut □ Affects parenchyma of liver, heart, pancreas – Secondary □ Due to multiple blood transfusions, increased iron intake, etc. □ Affects reticuloendothelial system (RES) (liver, spleen, nodes, marrow)

CT Findings • NECT ○ Homogeneously increased liver density – Up to 75-135 HU (normal 45-65 HU) • CECT ○ Makes excess iron in liver or spleen less apparent ○ Late stage: features of cirrhosis ± portal hypertension

– Common and underdiagnosed (affects up to 1/200 people in some European groups) – Abnormal increase in iron absorption by gut ○ Secondary hemochromatosis – Patients with increased iron intake: Increased consumption of medicinal or dietary iron – Anemic patients with ineffective erythropoiesis and multiple blood transfusions • Associated abnormalities ○ Cirrhosis, hepatocellular carcinoma ○ Progressive injury of heart, liver, and pancreas

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic during 1st decade of disease ○ Classic triad of primary hemochromatosis – Cirrhosis, diabetes, hyperpigmented skin ○ Other signs/symptoms – Congestive heart failure, arrhythmias – Arthralgias, impotence, gonadal atrophy • Complications ○ Periportal fibrosis leads to cirrhosis in late stage ○ Hepatocellular carcinoma (14-30%) ○ Insulin-dependent diabetes mellitus (30-60%) ○ Cardiac failure (30%)

Demographics • Gender ○ M:F = 10:1 ○ Women protected by iron loss during menstruation and pregnancy

MR Findings

Natural History & Prognosis

• T1WI ○ Decreased signal intensity in liver • T2WI ○ Primary: Marked signal loss in liver ± pancreas, heart, etc. ○ Secondary: Marked signal loss in both liver and spleen • T1WI GRE ○ Signal dropout from liver on in-phase

• Normal life expectancy with early diagnosis and treatment ○ Deferoxamine (iron chelation therapy) ○ Phlebotomies in precirrhotic stage • Life expectancy of untreated patients: 4.4 years after diagnosis

Imaging Recommendations

Image Interpretation Pearls

• Best imaging tool ○ MR T2* GRE for diagnosing hepatic hemochromatosis

• Primary form: Look for pancreatic (and other organ) involvement • Secondary: Look for splenic involvement • MR advantage: Other disorders do not simulate appearance of liver iron overload on MR as they do on CT • Due to phlebotomy or chelation, liver may appear normal attenuation on CT

DIFFERENTIAL DIAGNOSIS Amiodarone Therapy • Iodine-containing antiarrhythmic medication • Diffuse, homogeneously dense liver on NECT

Glycogen Storage Disease • Increased or decreased attenuation of liver on NECT ○ Depends on specific type of disease

PATHOLOGY

Liver

TERMINOLOGY

DIAGNOSTIC CHECKLIST

SELECTED REFERENCES 1. 2. 3.

Leitman SF: Hemochromatosis: the new blood donor. Hematology Am Soc Hematol Educ Program. 2013:645-50, 2013 Sirlin CB et al: Magnetic resonance imaging quantification of liver iron. Magn Reson Imaging Clin N Am. 18(3):359-81, 2010 Queiroz-Andrade M et al: MR imaging findings of iron overload. Radiographics. 29(6):1575-89, 2009

General Features • Etiology ○ Primary (hereditary) hemochromatosis – Autosomal recessive disorder 681

Liver

Hemochromatosis

(Left) In-phase GRE MR sequence in a 37-year-old man with primary hemochromatosis shows a striking loss of signal from liver parenchyma. The spleen and bone marrow are of normal signal intensity. (Right) Opposed-phase GRE in the same case shows less signal loss from the liver, a characteristic feature of excess hepatic iron and the opposite of the signal loss pattern seen with hepatic steatosis.

(Left) In this 71-year-old man with secondary hemochromatosis the liver is of very low intensity on this T2W MR sequence, owing to excessive iron deposition. Also seen is a spherical hepatic mass . (Right) Nonenhanced T1WI MR sequence in the same case shows the hepatic mass .

(Left) In the same case, an arterial phase contrastenhanced T1WI MR sequence shows bright enhancement of the mass , indicating hypervascularity. (Right) Delayed phase T1W MR in the same case shows contrast washout from the mass , as well as a capsule, typical features of HCC in the setting of hemochromatosis.

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Hemochromatosis Liver

(Left) Axial NECT in a 54-yearold woman with sickle cell anemia shows liver parenchyma that is much higher in attenuation than muscle or kidney. The spleen could not be used as an internal standard in this woman since it was infarcted and calcified. Note the high attenuation of several lymph nodes . (Right) CT section in the same patient shows dense pigment, probably calcium as well as iron, in multiple lymph nodes . No iron deposition is evident within the pancreas.

(Left) Axial NECT in a young woman with sickle cell disease shows a small and heavily calcified spleen (autosplenectomy). Without the spleen as a reference standard, it is hard to appreciate increased attenuation of the liver. (Right) Axial T2WI in a 25year-old woman with sickle cell anemia shows striking absence of signal within the liver, spleen , and bone marrow . Note the small size of the spleen due to chronic infarction. The pancreas is of normal size and intensity.

(Left) On T1WI GRE in-phase MR in this patient with hemochromatosis, there is both diffuse and focal loss of signal from the liver, especially within the lateral segment of the liver . (Right) On this opposed-phase GRE MR of the same patient, there is no signal loss from the liver. This is the opposite phenomenon as would be seen in focal steatosis, in which the signal loss would be evident on the opposed-phase images (acquired at a shorter echo time at 1.5 T).

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Liver

Wilson Disease KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Autosomal recessive disorder in which copper (Cu) accumulates pathologically in liver and other organs

• Presentation: Chronic hepatitis, cirrhosis, acute liver failure in adolescent or young adult • Acute fulminant presentation of Wilson disease most often in females (M:F = 1:2) • Prevalence: 1 in 30,000 (not rare) • Diagnosis: Liver biopsy and copper quantitation ○ Presence of Kayser-Fleisher rings and low level of ceruloplasmin sufficient to diagnose Wilson disease • Therapy: Copper chelation or transplantation ○ Those with acute hepatic failure have worse prognosis ○ Initial and maintenance therapy with copper chelation ○ Liver transplantation cures the disease and prevents recurrence

IMAGING • Spectrum of hepatic injury is nonspecific; fatty infiltration or cirrhosis indistinguishable from other etiologies ○ Multiple regenerating nodules (NECT or MR), same as other cirrhotic nodules • CT and MR for evaluation of cirrhosis and HCC ○ Not for diagnosis of Wilson disease ○ There are no specific imaging features for hepatic injury due to Wilson disease

TOP DIFFERENTIAL DIAGNOSES • Steatosis (fatty liver) • Hepatitis

PATHOLOGY • Steatosis

fibrosis and ultimately cirrhosis

(Left) Hematoxylin & eosin stained section shows features of steatohepatitis in Wilson disease (WD) with steatosis and glycogenated nuclei . (Courtesy J. Misdraji, MD.) (Right) Aldehyde fuchsin stain shows darkly staining granules of copper-associated protein (metallothionein) in periportal hepatocytes . (Courtesy J. Misdraji, MD.)

(Left) Axial NECT shows a nodular shrunken liver, typical of cirrhosis. Within the liver are innumerable hyperdense nodules that are typical of cirrhotic regenerating nodules, which are not necessarily indicative of Wilson disease. (Right) Axial venous phase CECT in the same patient shows that the regenerating nodules become nearly isodense with the liver, as usual. Signs of portal hypertension are evident, including ascites and varices. Cirrhosis was due to Wilson disease in this patient.

684

Wilson Disease

• Wilson disease (WD)

Synonyms

Gross Pathologic & Surgical Features

• Hepatolenticular degeneration

• Steatosis, followed by fibrosis and ultimately cirrhosis

Definitions

Microscopic Features

• Autosomal recessive disorder in which copper (Cu) accumulates pathologically ○ Primarily within liver and subsequently in neurologic system and other tissues

• Hepatic sinusoidal and periportal deposition of copper • Copper deposition incites inflammatory reaction, leading to cirrhosis

Abbreviations

IMAGING General Features • Best diagnostic clue ○ Early onset of cirrhosis, but no specific imaging features • Location ○ Early: Diffuse distribution of copper in liver cytoplasm ○ Later: Within lysosomes, then throughout liver nodules • Key concepts ○ There are no specific imaging features for hepatic injury due to Wilson disease

CT Findings • Spectrum of hepatic injury nonspecific; changes of fatty infiltration or cirrhosis frequently indistinguishable from other etiologies • Copper has high atomic number and can cause elevation of liver density on CT ○ Unusual finding because coexisting fatty infiltration diminishes hepatic parenchymal attenuation • Multiple hyperdense regenerating nodules (on NECT) ○ Identical to those in other cirrhotic livers • Multiple small, dysplastic nodules enhancing at arterial phase (unusual, nonspecific finding)

MR Findings • Copper deposition has no effect on MR • Iron in regenerative nodules causes hypointensity on T1WI and T2WI

Imaging Recommendations • Best imaging tool ○ CT and MR for evaluation of cirrhosis – Not for diagnosis of Wilson disease

DIFFERENTIAL DIAGNOSIS Steatosis (Fatty Liver) • NECT: Density of hepatic parenchyma less than spleen • Presence of normal vessels coursing through

Hepatitis • Hepatomegaly, periportal edema, lymphadenopathy • Usually does not alter attenuation of liver

CLINICAL ISSUES Presentation • Clinical profile ○ Chronic hepatitis, cirrhosis, acute liver failure – In adolescents or young adults ○ Acute fulminant hepatitis: Presents acutely with signs of jaundice, ascites that progresses to encephalopathy, and liver failure ○ Lab data: Serum ceruloplasmin < 20 mg/dL ○ Diagnosis: Liver biopsy and copper quantitation – Hepatic copper content > 250 μg/g dry weight – Presence of Kayser-Fleisher rings and low level of ceruloplasmin sufficient to diagnose WD

Demographics • Gender ○ Acute fulminant presentation of WD most often in females (M:F = 1:2) • Epidemiology ○ Prevalence: 1 in 30,000 (not rare)

Natural History & Prognosis • Deposition to toxic levels occurs in basal ganglia, renal tubules, cornea, bones, joints • Cirrhosis associated with WD also predisposed to hepatocellular carcinoma • Acute and early presentations like fulminant hepatic failures have poor outcome • Good prognosis with chelation (early) and transplantation (late)

Treatment • Initial and maintenance therapy with copper chelation • Liver transplantation cures the disease and prevents recurrence

SELECTED REFERENCES 1. 2. 3. 4. 5.

PATHOLOGY

6.

General Features

7.

• Etiology

Liver

○

biliary excretion of copper, intestinal absorption of copper, abnormal urinary excretion of copper • Genetics ○ Autosomal recessive disorder

TERMINOLOGY

Schilsky ML: Liver transplantation for Wilson's disease. Ann N Y Acad Sci. 1315:45-9, 2014 Weiss KH et al: Clinical considerations for an effective medical therapy in Wilson's disease. Ann N Y Acad Sci. 1315:81-5, 2014 Eapen CE: Copper and liver disease. Gut. 61(1):63, 2012 Bennett J et al: Clinical molecular diagnosis of Wilson disease. Semin Liver Dis. 31(3):233-8, 2011 Harada M et al: Excess copper chelating therapy for Wilson disease induces anemia and liver dysfunction. Intern Med. 50(14):1461-4, 2011 Johncilla M et al: Pathology of the liver in copper overload. Semin Liver Dis. 31(3):239-44, 2011 Cheon JE et al: Clinical application of liver MR imaging in Wilson's disease. Korean J Radiol. 11(6):665-72, 2010

685

Liver

Wilson Disease

(Left) Axial T1WI MR of a 19year-old man with liver injury subsequently found to be due to Wilson disease shows a small scarred liver and splenomegaly . (Right) Axial T2WI MR in the same patient shows ascites ,a small nodular liver with innumerable tiny hypointense nodules, typical of regenerative nodules and not specific for Wilson disease.

(Left) Axial NECT in the same patient shows a small nodular liver, widened fissures, and signs of portal hypertension. The attenuation of the liver is slightly less than that of the spleen. Liver biopsy and other tests confirmed the presence of WD. Most patients with WD have no imaging findings that would suggest excess copper within the liver. (Right) Hematoxylin & eosin-stained liver biopsy in Wilson disease shows portal and periportal chronic hepatitis and apoptotic hepatocytes . (Courtesy J. Misdraji, MD.)

(Left) Axial CECT of a 14-yearold boy with abnormal liver function tests shows cirrhotic morphology with a nodular contour and widened fissures. There are signs of portal hypertension, including ascites and varices . (Right) Axial CECT in the same patient also shows varices . There is nothing specific about the appearance of the liver to suggest Wilson disease. The onset of cirrhosis in a child was the main clinical clue, but diagnosis required liver biopsy.

686

Wilson Disease Liver

(Left) Coronal MR of a 24year-old woman with abnormal liver function shows a small liver and an enlarged spleen. (Right) Axial T2WI in the same patient shows innumerable small, hypointense regenerating nodules that are identical to those seen in other etiologies of cirrhosis.

(Left) Axial T1WI GRE in-phase MR in the same patient shows only periportal edema , a nonspecific sign of hepatitis (among other etiologies). (Right) Axial T1WI GRE opposed-phase MR in the same patient shows diffuse signal dropout from the liver, indicating steatosis.

(Left) Axial T1WI GRE in-phase MR in the same patient shows widening of hepatic fissures, a typical, though nonspecific, sign of cirrhosis. (Right) Axial T1WI GRE opposed-phase MR in the same patient shows diffuse hepatic signal loss, indicating steatosis. Liver biopsy and other tests confirmed both steatosis and excess copper deposition in the liver due to Wilson disease.

687

Liver

Hepatomegaly KEY FACTS

TERMINOLOGY • Enlargement of liver due to underlying pathologic process

IMAGING • Best diagnostic clue: Hepatic length > 15 cm ○ Normal liver length 8-12 cm for men, 6-10 cm for women in midclavicular line ○ But consider other dimensions and volume of liver • Best imaging tool: Longitudinal US or coronal CT or MR

TOP DIFFERENTIAL DIAGNOSES • Riedel lobe • Caudate hypertrophy in Budd-Chiari or primary sclerosing cholangitis • Liver displacement by COPD • Lobar regeneration after major liver resection

CLINICAL ISSUES • Most common signs/symptoms

(Left) Longitudinal ultrasound in a 44-year-old man with a history of hepatitis B infection shows marked enlargement of the right lobe of the liver , extending caudally below the level of the kidney . (Right) Longitudinal ultrasound in a 38-year-old woman with nonalcoholic steatohepatitis reveals marked hepatic enlargement. Note the right hepatic lobe extending below the level of the right kidney as well as echogenicity greater than that of the kidney due to diffuse steatosis.

(Left) Coronal CECT reformation of a 52-year-old man with metastatic colon cancer shows marked enlargement of the liver with diffuse metastases throughout the right lobe . (Right) Venous phase coronal CECT of a 27-year-old woman with leukemia and new onset of RUQ pain shows an enlarged and heterogeneous liver with distended hepatic veins and IVC due to passive congestion of the liver. Drug toxicity accounted for the cardiac dysfunction.

688

○ Palpable liver edge below costal margin • Other signs/symptoms ○ Jaundice, RUQ pain, fever, abnormal liver function tests • Prognosis: Benign outcome to fulminant liver failure • Biopsy often required for definitive diagnosis

DIAGNOSTIC CHECKLIST • Hepatitis, steatosis, passive congestion, and diffuse tumor are most common causes • Image interpretation pearls ○ Consider triphasic CT to detect and characterize mass lesions ○ Can also assist in diagnosing other etiologies ○ e.g., passive hepatic congestion, steatosis

Hepatomegaly

PATHOLOGY

Definitions

General Features

• Enlargement of liver due to underlying pathologic process

• Etiology ○ Infection – Viral hepatitis (acute or chronic) – Abscess (pyogenic or amebic) ○ Infiltrative disorder – Metastatic disease – Hepatocellular carcinoma (especially if multifocal) ○ Metabolic disorder – Hemochromatosis, Wilson disease, glycogen storage disease, nonalcoholic steatohepatitis □ All causes of fatty liver (steatosis) ○ Hematologic causes – Sickle cell anemia, hemolytic anemia, myeloma, leukemia, lymphoma ○ Vascular causes – Congestive heart failure, right heart failure, constrictive pericarditis – Signs of passive hepatic congestion □ Distended hepatic veins and IVC, retrograde opacification of IVC on arterial phase CECT, mottled liver enhancement ○ Biliary causes ○ Drugs

IMAGING General Features • Best diagnostic clue ○ Hepatic length and volume are increased • Location ○ Liver protrudes beyond costal margin • Size ○ > 15 cm measured from midhepatic line • Morphology ○ Focal enlargement due to mass lesion ○ Diffuse enlargement due to infection, passive hepatic congestion, or infiltrative disorder

Imaging Recommendations • Best imaging tool ○ Longitudinal US or coronal triphasic CT – Detect and characterize underlying mass • Protocol advice ○ CECT or MR to detect and characterize focal or diffuse disease – Coronal reformations on CT ○ In- and out-of-phase MR or NECT to detect steatosis

CT Findings • Diffuse enlargement best demonstrated on coronal views ○ May have hyper- or hypovascular masses, focal lesions, or metastatic abscess

CLINICAL ISSUES Presentation

• In- and out-of-phase MR ○ Lipid with signal dropout on out-of-phase imaging

• Most common signs/symptoms ○ Palpable liver edge below costal margin • Other signs/symptoms ○ Jaundice, RUQ pain, fever, abnormal liver function tests – Acutely swollen liver may stretch hepatic capsule and causes RUQ pain and tenderness

Ultrasonographic Findings

Natural History & Prognosis

• Length in midhepatic (midclavicular) line > 15 cm • Liver tip extends beyond right kidney

• Ranges from benign outcome to fulminant liver failure

MR Findings

DIFFERENTIAL DIAGNOSIS Riedel Lobe • Anatomic variant (not true hepatic lobe), not pathologic • Tongue-like caudal protrusion of right lobe of liver

Caudate Hypertrophy in Budd-Chiari Syndrome • Caudate hypertrophies in response to necrosis of more peripheral segments of liver • Similar caudate hypertrophy seen in primary sclerosing cholangitis (PSC)

Liver Displacement by Chronic Obstructive Pulmonary Disease (COPD) • Caudal margin of liver displaced inferiorly by inverted diaphragm

Lobar Regeneration After Major Liver Resection

Liver

TERMINOLOGY

Treatment • Biopsy often required for definitive diagnosis

DIAGNOSTIC CHECKLIST Consider • Underlying infiltrating tumor or storage disease

Image Interpretation Pearls • Consider triphasic CT to detect and characterize mass lesions and other causes

SELECTED REFERENCES 1. 2. 3. 4.

Mogrovejo E et al: Characterization of the syndrome of acute liver failure caused by metastases from breast carcinoma. Dig Dis Sci. 59(4):724-36, 2014 Gao H et al: Definitive diagnosis of hepatic sinusoidal obstruction syndrome induced by pyrrolizidine alkaloids. J Dig Dis. 13(1):33-9, 2012 Gertz MA: How to manage primary amyloidosis. Leukemia. 26(2):191-8, 2012 Udell JA et al: Does this patient with liver disease have cirrhosis? JAMA. 307(8):832-42, 2012

• Remainder of liver undergoes regeneration after major hepatic resection

689

Liver

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs) KEY FACTS

TERMINOLOGY

• Focal sparing with fatty liver

• Transient increase in hepatic attenuation (THAD) or intensity (THID) during arterial phase CT (or MR) due to regional variations in balance between hepatic arterial and portal venous blood flow

PATHOLOGY

IMAGING • Wedge-shaped areas of increased attenuation on arterial phase imaging ○ Become isodense (isointense) on venous and delayed phases • Pseudolesions on nuclear medicine studies ○ e.g., "hot" accumulation of Tc-sulfur colloid in left lobe of liver in patients with SVC obstruction ○ "Hot" accumulation of FDG within THAD on PET/CT

TOP DIFFERENTIAL DIAGNOSES • Hypervascular liver mass • Hemangioma

(Left) Arterial phase CECT in a man recovering from abdominal gunshot wounds shows hyperenhancement of the anterior right lobe segments of the liver due to septic thrombosis of the anterior branch of the right portal vein . (Right) CECT of an elderly man with septic thrombophlebitis due to diverticulitis shows hyperperfusion of the anterior right lobe of the liver due to thrombosis of the anterior branch of the right portal vein and compensatory increased flow from the hepatic artery .

(Left) Arterial phase CECT of a 54-year-old woman with a hypercoagulable condition shows thrombosis of the posterior branch of the right portal vein . Compensatory increased flow through the hepatic artery accounts for the posterior segmental transient hepatic attenuation difference (THAD). Ascites is also noted due to hepatic injury from the portal vein thrombosis. (Right) Portal venous phase CECT in the same case shows uniform enhancement of the liver, the portal vein thrombus , and ascites .

690

• THAD due to decreased portal flow ○ Segmental, peripheral portal vein thrombosis ○ Direct compression or occlusion of portal vein by mass ○ Elevated sinusoidal pressure (e.g., due to biliary obstruction) • THAD due to increased arterial inflow ○ Peripheral AP shunts in cirrhosis ○ Hypervascular masses may draw flow (siphon effect) ○ Post-traumatic or congenital AV fistula • 3rd inflow alternative or additional source of venous flow to liver (e.g., SVC occlusion)

DIAGNOSTIC CHECKLIST • Check portal venous phase images for subtle mass at apex of wedge-shaped THAD

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs)

Abbreviations • Transient hepatic attenuation difference (THAD) • Transient hepatic intensity difference (THID)

Definitions • Transient increase in hepatic attenuation (or intensity) during arterial phase CT (or MR) due to regional variations in balance between hepatic arterial and portal venous blood flow

IMAGING General Features • Best diagnostic clue ○ Wedge-shaped areas of increased attenuation on arterial phase imaging – Become isodense (isointense) on portal venous and delayed phases • Location ○ Peripheral, extending to capsular surface of liver • Size ○ Variable, depending on etiology – Often segmental or lobar, especially with neoplastic etiology • Morphology ○ Straight margins, wedge-shaped – Usually subsegmental ○ Segmental or lobar THADs should have identifiable etiology ○ Small subcapsular THADs more commonly occur in setting of cirrhosis with no focal lesion identified ○ Rounded lesion at apex of wedge (or triangle) usually represents neoplastic etiology for THAD

Imaging Recommendations

Nuclear Medicine Findings • Same foci and pathophysiology of THAD may result in pseudolesions on nuclear medicine studies ○ e.g., "hot" accumulation of Tc sulfur colloid in left lobe of liver in patients with SVC obstruction ○ "Hot" accumulation of FDG within a THAD on PET-CT – Easily misinterpreted as a focus of tumor

DIFFERENTIAL DIAGNOSIS Hypervascular Liver Mass • Hepatocellular carcinoma, focal nodular hyperplasia, or hypervascular metastases (carcinoid, neuroendocrine most common) • Usually spherical or oval, not wedge-shaped • May show washout on portal venous phase imaging • May be associated with arterioportal shunting or THAD ○ But mass should be identified as separate from THAD ○ Mass is typically spherical lesion ○ May cause rounded lesion at apex of wedge-shaped THAD

Focal Confluent Fibrosis • Capsular retraction and volume loss in cirrhotic liver • Wedge-shaped area of increased attenuation on delayed, not arterial phase • Often occurs in segment 4 of liver

Hemangioma • Nodular discontinuous peripheral enhancement • Capillary or "flash fill" hemangiomas may appear uniformly hyperdense on arterial phase imaging • Attenuation of lesion tracks blood pool • May have associated arterioportal shunting or THAD ○ Due to siphon effect more often than compression of portal vein branch

• Best imaging tool ○ CECT with arterial and portal venous phase imaging • Protocol advice ○ Obtain arterial phase 25-40 seconds after IV contrast bolus – Must have adequate volume (> 100 mL) and rate ( 3 mL/sec) of IV contrast administration ○ Portal venous phase 60-80 seconds after IV bolus

Focal Sparing With Fatty Liver

CT Findings

General Features

• Area with straight margins and wedge-shaped morphology peripherally in liver on arterial phase imaging ○ Becomes isodense and inconspicuous on venous and delayed phase images • May demonstrate focal hepatic or perihepatic mass, or portal or hepatic vein thrombosis as specific cause of THAD

• Etiology ○ Normal hepatic blood supply and pharmacodynamics of contrast enhancement – Arterial phase of contrast enhancement (~ 20-40 sec) □ Iodinated contrast reaching liver via hepatic artery is diluted 3:1 in sinusoids by unopacified portal venous blood – Venous phase of imaging (~ 60-80 sec) □ Opacified blood is carried to liver via portal vein □ Results in maximum enhancement of liver parenchyma – Any process that portal venous inflow or arterial inflow will result in THAD ○ THAD due to decreased portal flow – Segmental, peripheral portal vein thrombosis

MR Findings • Arterial phase of gadolinium-enhanced MR shows areas of hyperenhancement (THID) ○ Becomes isointense to liver on venous and delayed phases

Ultrasonographic Findings • No corollary findings, except with contrast-enhanced US ○ e.g., with microbubble contrast agent

Liver

TERMINOLOGY

• Relatively high-attenuation areas of normal liver surrounded by low-attenuation fatty liver • Most often in segments 4A and 4B adjacent to gallbladder fossa • More evident on nonenhanced CT or MR, unlike THAD

PATHOLOGY

691

Liver

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs) □ Hypercoagulable (prothrombotic) conditions □ Septic thrombophlebitis (e.g., from appendicitis or diverticulitis) – Extrinsic compression of liver (e.g., by ribs, subcapsular hematoma) – Direct compression or occlusion of portal vein by mass (e.g., tumor or abscess) – Elevated sinusoidal pressure (due to cholangitis or biliary obstruction) ○ THAD due to increased arterial inflow – Peripheral AP shunts in cirrhosis – Hypervascular masses □ May draw arterial flow to surrounding liver by sump or siphon effect □ Hepatocellular carcinoma □ Hypervascular liver metastases (e.g., neuroendocrine) □ Capillary hemangioma □ Pyogenic liver abscess – Post-traumatic or congenital AV fistula □ Following liver biopsy □ Following penetrating or blunt trauma □ Postoperative □ Hereditary hemorrhagic telangiectasia (OslerWeber-Rendu) ○ 3rd inflow alternative or additional source of venous flow to liver – Gallbladder venous drainage into adjacent liver □ Cholecystitis may result in enhancement of adjacent liver □ Origin of rim sign seen on CECT (and on Tc-HIDA scan) – Paraumbilical and paradiaphragmatic venous system □ Communication between portal and systemic venous systems □ e.g., THAD in segment 4 due to transhepatic collateral flow in setting of occlusion of superior or inferior vena cava □ Origin of "hot" quadrate (medial segment) sign on Tc-sulfur colloid scan • Associated abnormalities ○ Hypercoagulable (prothrombotic) states for portal venous occlusion ○ Appendicitis, diverticulitis with septic portal venous occlusion ± liver abscess ○ Primary or metastatic tumor

Gross Pathologic & Surgical Features • Tumor invading or obstructing veins ○ Hepatocellular carcinoma > cholangiocarcinoma > metastases

Microscopic Features • Normal histology within focus of THAD itself • Hepatic neoplasm or other etiology in adjacent tissue

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most symptoms are due to underlying cause – Systemic venous thrombosis, tumor, or infection 692

○ THAD itself usually asymptomatic – High-flow traumatic or congenital AV fistulas may result in high output heart failure □ Especially in patients with hereditary hemorrhagic telangiectasis (Osler-Weber-Rendu)

Demographics • Age ○ Any • Epidemiology ○ Increased incidence in cirrhotic patients ○ Relatively common in metastases from tumors of gastrointestinal tract – Spread to liver via portal vein □ Metastases may occlude portal vein branch

Natural History & Prognosis • Poor prognosis related to portal venous invasion ○ Hepatocellular carcinoma, cholangiocarcinoma, metastases • Hypercoagulable (prothrombotic) conditions must be recognized and treated ○ Imaging may provide 1st clue to these conditions • Underlying source of septic emboli must be identified ○ Usually "smoldering" diverticulitis or appendicitis

Treatment • Treat underlying disease (e.g., infection or tumor)

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Look carefully for small hepatic tumor at apex of THAD

SELECTED REFERENCES 1.

2. 3. 4. 5. 6.

7. 8.

9.

Bhattacharya A et al: Segmental hepatic concentration of 18F-FDG-labeled autologous leukocytes causing a "pseudo-lesion" on PET/CT in a patient with transient hepatic attenuation difference. Clin Nucl Med. 38(10):e399-401, 2013 Ames JT et al: Septic thrombophlebitis of the portal venous system: clinical and imaging findings in thirty-three patients. Dig Dis Sci. 56(7):2179-84, 2011 Desser TS: Understanding transient hepatic attenuation differences. Semin Ultrasound CT MR. 30(5):408-17, 2009 Torabi M et al: CT of nonneoplastic hepatic vascular and perfusion disorders. Radiographics. 28(7):1967-82, 2008 Ahn JH et al: Nontumorous arterioportal shunts in the liver: CT and MRI findings considering mechanisms and fate. Eur Radiol. 20(2):385-94, 2010 Kim SW et al: Diffuse pattern of transient hepatic attenuation differences in viral hepatitis: a sign of acute hepatic injury in patients without cirrhosis. J Comput Assist Tomogr. 34(5):699-705, 2010 Pradella S et al: Transient hepatic attenuation difference (THAD) in biliary duct disease. Abdom Imaging. 34(5):626-33, 2009 Hwang SH et al: Transient hepatic attenuation difference (THAD) following transcatheter arterial chemoembolization for hepatic malignancy: changes on serial CT examinations. Eur Radiol. 18(8):1596-603, 2008 Colagrande S et al: Transient hepatic intensity differences: part 1, Those associated with focal lesions. AJR Am J Roentgenol. 188(1):154-9, 2007

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs) Liver

(Left) Arterial phase axial CECT of a 60-year-old man with cirrhosis shows 1 of several peripheral, small, wedge-shaped, hypervascular foci . (Right) Axial portal venous phase image in the same case shows no lesion. This is a typical appearance for arterioportal (AP) shunts, which are common within the cirrhotic liver. Imaging features that favor AP shunt over HCC include peripheral, subcapsular location, small size, wedge shape, and no corresponding lesion on venous or delayed phase imaging.

(Left) Axial CECT during arterial phase imaging in a 67year-old man presenting with midepigastric pain, weight loss, and mildly elevated liver function tests shows a wedgeshaped THAD distal to a small hypoattenuating liver metastasis from pancreatic carcinoma. Note the low-attenuation pancreatic mass involving the pancreatic head. (Right) Axial arterial phase CECT in the same patient reveals a very small metastasis at the apex of the triangular THAD .

(Left) Axial CECT in a 57-yearold woman presenting with weight loss, vague abdominal pain, and jaundice shows a dilated left main bile duct with a left lobar THAD . (Right) Coronal CECT reformation in the same case shows the dilated bile ducts and left lobe THAD due to a cholangiocarcinoma. Biliary obstruction causes focal increased sinusoidal pressure and regionally decreased portal flow, accounting for the lobar THAD in this case.

693

Liver

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs)

(Left) Arterial phase CECT of a 46-year-old man with cirrhosis and biopsy-caused THAD shows hyperenhancement of a portion of the lateral segment of the liver and early enhancement of the portal vein branch that drains this segment . This represents an arterioportal shunt and is the result of the prior biopsy of the liver at this site. (Right) The portal venous phase image in the same patient appears normal, including the lateral segment portal vein branch .

(Left) Arterial phase CECT of a 60-year-old man with THAD due to HCC shows an enlarged branch of the right hepatic artery and a brightly enhancing lesion in the right lobe . (Right) Arterial phase CECT image in the same case shows a heterogeneously hypervascular tumor (HCC) . Just peripheral to the tumor, there is a wedge-shaped zone of hypervascularity that is a transient hepatic attenuation difference (THAD) or perfusion abnormality rather than tumor.

(Left) Arterial phase CECT in the same patient shows multiple hypervascular tumor foci . The THAD distal to the largest tumor mass is due to the HCC obstructing the portal venous radicle to this segment of liver. (Right) Axial portal venous phase CECT in this case shows less evidence of the THAD and washout of contrast from the HCC masses . It is important to distinguish THADs from a tumor, which might otherwise cause an overestimation of tumor size.

694

Transient Hepatic Attenuation or Intensity Difference (THADs and THIDs) Liver

(Left) CECT in a young woman shows a large mass in the liver that is homogeneously hypervascular, typical of focal nodular hyperplasia (FNH). Note hyperenhancement of the entire right lobe of the liver on this arterial phase image, probably due to the "siphon effect" of the hypervascular FNH and possible compression of the right portal vein. (Right) Portal venous phase CECT in the same case shows that the THAD and FNH are nearly isodense with underlying liver.

(Left) Axial CECT of a 33-yearold woman with a THAD due to liver abscess shows a large, multiloculated mass with a contrast-enhancing wall and septa, typical for a pyogenic abscess. Note the hyperenhancement of the right lobe of the liver . (Right) CECT in the same case shows a right lobar THAD that is due to 2 factors: The "siphon effect" of the abscess drawing additional arterial flow toward the right lobe, and, more importantly, the thrombosis of the branches of the right portal vein .

(Left) Axial arterial phase CECT shows hyperdense enhancement of the medial left lobe via collateral veins that traverse the chest wall , diaphragm, and liver parenchyma , the classic appearance of collateral venous flow in a patient with obstruction of the superior vena cava. (Right) Coronal reformatted CT in the same case shows occlusion of the SVC, chest wall collateral veins , the intrahepatic collaterals , and the densely opacified medial segment .

695

Liver

Arterioportal Shunt KEY FACTS

TERMINOLOGY • Communication between branch of hepatic artery and portal venous system

IMAGING • Best diagnostic clue ○ Wedge-shaped area of hyperattenuation with straight margins seen during arterial phase of CECT or MR ○ Becomes isodense to hepatic parenchyma during portal venous phase of CECT or gadolinium-enhanced MR • Peripherally within hepatic segment or lobe • Usually 1.5 cm (e.g., cirrhotic arterioportal [AP] shunts) ○ Larger in some cases of post-biopsy AP shunts ○ Early enhancement of peripheral portal vein (PV) branches prior to visualization of main PV

TOP DIFFERENTIAL DIAGNOSES • Hypervascular liver mass (e.g., hepatocellular carcinoma [HCC])

(Left) Seen only on the arterial set of images are multiple peripheral, wedge-shaped, hyperenhancing foci in this 60-year-old man with cirrhosis due to chronic viral hepatitis. (Right) Axial arterial phase CECT in the same patient shows additional peripheral, wedge-shaped, hypervascular foci . Also note the large, "corkscrew" hepatic arterial branch , a typical feature of cirrhosis. The liver has a cirrhotic morphology with wide fissures.

(Left) Axial portal venous phase CECT in the same patient shows none of the peripheral hypervascular lesions, which have become isodense to liver. (Right) Axial delayed phase CECT shows no washout or other evidence of the focal peripheral lesions seen on arterial phase. AP shunts are common within the cirrhotic liver. Imaging features that favor AP shunt over HCC include peripheral, subcapsular location, small size, wedge shape, and no corresponding lesion on venous or delayed phase imaging.

696

○ Usually round or oval, not wedge-shaped ○ Usually shows washout on venous phase • Hemangioma ○ Attenuation tracks blood pool on all phases • Focal sparing with fatty liver ○ Not really hypervascular foci ○ Relatively high-attenuation areas of "normal" liver surrounded by low-attenuation fatty liver

PATHOLOGY • Small AP shunts are not amenable to biopsy ○ Too small; invisible on NECT and US

DIAGNOSTIC CHECKLIST • Small (< 1.5 cm) AP shunts are common in cirrhosis ○ If unassociated with focal lesion on MR, it is probably insignificant ○ Follow-up in ~ 6 months is indicated and adequate • Do not mistake multiple small AP shunts for multifocal HCC

Arterioportal Shunt

Abbreviations • Arterioportal (AP) shunt

Definitions • Communication between a branch of hepatic artery and portal venous system

IMAGING General Features • Best diagnostic clue ○ Nodular or wedge-shaped area of hyperattenuation with straight margins seen during arterial phase of CECT or gadolinium-enhanced MR ○ Becomes isodense to hepatic parenchyma during portal venous phase of CECT or gadolinium-enhanced MR • Location ○ Peripherally within hepatic segment or lobe • Size ○ Usually 1.5 cm (e.g., cirrhotic AP shunts) – Larger in some cases of post-biopsy AP shunts – Transient hepatic attenuation difference (THAD) and transient hepatic intensity difference (THID) can be much larger □ Can involve entire hepatic segment or lobe • Morphology ○ Wedge-shaped with straight margins

Imaging Recommendations • Best imaging tool ○ Multiphasic CECT or gadolinium-enhanced MR • Protocol advice ○ Arterial phase acquisition of CECT or MR at 25-35 seconds after injection – Followed by venous phase (60-70 seconds) and delayed phase (~ 120 seconds)

CT Findings • Arterial phase imaging ○ Early enhancement of peripheral portal vein (PV) branches prior to visualization of main PV ○ Peripheral wedge-shaped area of increased attenuation with straight edges within affected segment or lobe – Hyperdense areas on arterial phase imaging • Portal venous and delayed phase imaging ○ Area of previously increased attenuation equilibrates, becomes nearly isodense with rest of liver ○ Cause of larger AP shunt (e.g., PV thrombosis, hepatic mass) may be more visible during portal venous phase

MR Findings • T1WI ○ T1WI and T2WI usually normal for nontumoral causes of AP shunts • T2WI ○ Rarely slight increase in T2 signal in affected lobe or segment of nontumoral shunts ○ Underlying mass may cause abnormal T2 signal with AP shunts related to hepatic masses or tumors • Dynamic gadolinium-enhanced MR

○ Arterial phase imaging (25-35 seconds after injection) – Wedge-shaped area of increased signal intensity in segment or lobe of shunt ○ Venous and delayed phase imaging – Signal nearly isointense with rest of liver

Liver

TERMINOLOGY

Ultrasonographic Findings • Usually US does not detect small, peripheral AP shunts typical of cirrhotic liver • May detect cause of larger AP shunt ○ Mass lesion ○ PV thrombosis ○ Arterioportal fistula • Spectral Doppler may reveal "arterialized" waveform in PV for large AP shunt

DIFFERENTIAL DIAGNOSIS Hypervascular Liver Mass • Hepatocellular carcinoma, focal nodular hyperplasia, or hypervascular metastases ○ Carcinoid, neuroendocrine most common mets • Usually round or oval, not wedge-shaped • May show washout on portal venous phase imaging • May be associated with AP shunting ○ Due to hypervascularity (sump effect) ○ Or due to compression or occlusion of PV branch ○ Or shunting within malignant tumor

Focal Confluent Fibrosis • Common feature of advanced cirrhosis • Usually large, wedge-shaped area of decreased density on NECT, increased intensity on T2WI • Capsular retraction • Retention of contrast on 10-minute delayed images (CECT or C+ MR) • Often occurs in segment 4 of liver

Hemangioma • Usually spherical lesion • Nodular discontinuous peripheral enhancement • Capillary or "flash fill" hemangiomas may appear uniformly hyperdense on arterial phase imaging • Attenuation tracks blood pool on all phases • May rarely have associated AP shunting

Focal Sparing With Fatty Liver • Relatively high-attenuation areas of "normal" liver surrounded by low-attenuation fatty liver • Not really hypervascular foci • Most often in segments 4A and 4B • Often around gallbladder fossa

PATHOLOGY General Features • Etiology ○ Most small arterioportal shunts are incidental findings in cirrhotic liver ○ Reflect the altered hemodynamics of cirrhosis – Hepatic fibrosis portal hypertension decreased portal venous flow to liver increased arterial flow 697

Liver

Arterioportal Shunt ○ Larger AP shunts or transient attenuation differences (THAD [or THID for MR]) – May be classified as neoplastic vs. nonneoplastic according to underlying etiology – Neoplastic: Hepatocellular carcinoma, cholangiocarcinoma, metastatic, hemangioma – Nonneoplastic: Lesions with mass effect decreasing PV flow □ Hepatic abscess □ Subcapsular hematoma, biloma, abscess □ Portal or hepatic vein thrombosis – Trauma □ Shunt or fistula may result from liver biopsy □ Often see premature enhancement of portal vein branch accompanying injured artery □ Usually a transient and insignificant process that resolves spontaneously ○ May be classified according to vascular pathways of shunting – Trans-sinusoidal, via biliary plexus, anomalous venous drainage ○ Aberrant venous drainage – Parabiliary venous plexus □ Includes right gastric vein and veins of pancreaticoduodenal area ○ Aberrant blood supply (capsular veins, accessory cystic veins, aberrant right gastric vein) causes systemic venous blood to drain into sinusoids • Associated abnormalities ○ Hepatic tumor ○ PV thrombosis ○ Hepatic laceration ○ Abscess or infection

Natural History & Prognosis • Poor prognosis if AP shunt is related to PV invasion ○ Hepatocellular carcinoma ○ Cholangiocarcinoma ○ Metastases

Treatment • Directed at underlying cause ○ e.g., infection or tumor • If hemodynamically significant shunt, embolization may be required

DIAGNOSTIC CHECKLIST Consider • For segmental or lobar AP shunt or THAD ○ Usually due to portal vein branch occlusion ○ Look for bland or tumor thrombus or occlusion

Image Interpretation Pearls • Small (< 1.5 cm) AP shunts are common in cirrhosis ○ If unassociated with focal lesion on MR, it is probably insignificant ○ Follow-up in ~ 6 months is indicated and adequate

Reporting Tips • Do not mistake multiple small AP shunts for multifocal HCC

SELECTED REFERENCES 1.

2. 3.

Gross Pathologic & Surgical Features • Tumor invading or obstructing veins ○ Hepatocellular carcinoma > cholangiocarcinoma or metastases

4.

Microscopic Features

6.

• Small AP shunts are not amenable to biopsy ○ Too small ○ Cannot be seen on nonenhanced CT or US

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Symptoms are due to underlying cause (cirrhosis, tumor, or infection) ○ AP shunt itself is usually asymptomatic • Other signs/symptoms ○ High output congestive failure only with large AP shunts – May be seen in hereditary hemorrhagic telangiectasia

Demographics • Age ○ Any age • Epidemiology ○ Increased incidence in cirrhotic patients

698

5.

7.

8. 9. 10.

11. 12. 13.

Sonomura T et al: N-butyl cyanoacrylate embolization with blood flow control of an arterioportal shunt that developed after radiofrequency ablation of hepatocellular carcinoma. Korean J Radiol. 15(2):250-3, 2014 Kim TK et al: Hepatocellular nodules in liver cirrhosis: contrast-enhanced ultrasound. Abdom Imaging. 36(3):244-63, 2011 Nakamura Y et al: Clinical significance of the transitional phase at gadoxetate disodium-enhanced hepatic MRI for the diagnosis of hepatocellular carcinoma: preliminary results. J Comput Assist Tomogr. 35(6):723-7, 2011 Vogl TJ et al: Portal vein thrombosis and arterioportal shunts: effects on tumor response after chemoembolization of hepatocellular carcinoma. World J Gastroenterol. 17(10):1267-75, 2011 Ahn JH et al: Nontumorous arterioportal shunts in the liver: CT and MRI findings considering mechanisms and fate. Eur Radiol. 20(2):385-94, 2010 Mita K et al: Diagnostic sensitivity of imaging modalities for hepatocellular carcinoma smaller than 2 cm. World J Gastroenterol. 16(33):4187-92, 2010 Yoo HJ et al: Hepatocellular carcinoma in cirrhotic liver: double-contrastenhanced, high-resolution 3.0T-MR imaging with pathologic correlation. Invest Radiol. 43(7):538-46, 2008 Goto T et al: Osler-Weber-Rendu disease with esophageal varices and hepatic nodular change. Intern Med. 46(12):849-54, 2007 Kitade M et al: Intrahepatic cholangiocarcinoma associated with central calcification and arterio-portal shunt. Intern Med. 44(8):825-8, 2005 Sakata H et al: Prognostic factors for hepatocellular carcinoma presenting with macroscopic portal vein tumor thrombus. Hepatogastroenterology. 51(60):1575-80, 2004 Yoshimitsu K et al: Pitfalls in the imaging diagnosis of hepatocellular nodules in the cirrhotic and noncirrhotic liver. Intervirology. 47(3-5):238-51, 2004 Yoshimitsu K et al: Unusual hemodynamics and pseudolesions of the noncirrhotic liver at CT. Radiographics. 21 Spec No:S81-96, 2001 Koizumi J et al: Computed tomography during arterial portography under temporary balloon occlusion of the hepatic artery: evaluation of pseudolesions caused by arterio-portal venous shunts. Abdom Imaging. 25(6):583-6, 2000

Arterioportal Shunt Liver

(Left) Arterial phase CECT in a 54-year-old man with chronic hepatitis C, presenting for surveillance of cirrhosis, shows a small, peripheral, hypervascular focus . (Right) Subsequent portal venous (hepatic parenchymal) phase CECT in the same patient reveals that the small peripheral focus has disappeared. The "lesion" was still gone by a repeat CT 6 months later and is presumably a small arterioportal shunt, which is common in cirrhosis.

(Left) Arterial phase CECT in a 46-year-old man with cirrhosis and a history of a prior USguided liver biopsy shows hyperenhancement of a portion of the lateral segment of the liver and early enhancement of the portal vein branch that drains this segment , representing an arterioportal shunt, probably due to the prior liver biopsy at this site. (Right) Portal venous phase CECT in the same patient shows enhancement of the portal vein branch but otherwise appears normal.

(Left) Axial CECT in a 48-yearold woman who presented with progressive liver failure demonstrates an unusually large arterioportal shunt in the left lobe, most likely the result of a prior liver biopsy at this site. (Right) Axial CECT in the same patient illustrates a small cirrhotic liver with widened fissures and signs of portal hypertension, including splenomegaly and varices .

699

Liver

Portal Vein Occlusion KEY FACTS

TERMINOLOGY • Acute, chronic, or neoplastic occlusion of portal vein (PV) due to thrombosis or tumor invasion • Chronic PV occlusion with numerous periportal collaterals is referred to as "cavernous transformation"

CLINICAL ISSUES

• Best imaging tool ○ Color Doppler US initially: Highly accurate and cost effective ○ CT or MR: Complete evaluation and to search for cause

• PV tumor invasion (usually from hepatocellular carcinoma) is associated with poor clinical outcome • Primary PV thrombosis may mimic cirrhosis ○ Results in dysmorphic and malfunctioning liver • Treatment: Anticoagulation for acute bland thrombosis or hypercoagulable condition ○ Add antibiotics for septic thrombophlebitis

TOP DIFFERENTIAL DIAGNOSES

DIAGNOSTIC CHECKLIST

• Streaming artifact • Extrinsic compression • Budd-Chiari syndrome

• Tumor thrombus expands lumen, enhances, and is contiguous with parenchymal mass • Thrombosis or fibrosis of extrahepatic portal vein may complicate or preclude liver transplantation

IMAGING

PATHOLOGY • Most often associated with hepatic cirrhosis and pancreatitis

(Left) Axial CECT in a 55-yearold man with hepatitis B who presented for routine CT screening to rule out HCC shows cavernous transformation of the portal vein with numerous small collateral veins in the porta hepatis and hepatoduodenal ligament. The main portal vein cannot be identified. (Right) CT through the porta hepatis in the same patient reveals no normal portal vein branches, only innumerable tiny collateral veins , diagnostic of cavernous transformation and chronic portal vein occlusion.

(Left) Longitudinal grayscale ultrasound image obtained through the porta hepatis in a 51-year-old woman presenting with vague RUQ pain and a recent elevation of liver function tests reveals no apparent abnormalities of the portal vein . (Right) Longitudinal power Doppler ultrasound obtained in the same patient in the same field of view reveals an acute thrombosis of the portal vein with a complete absence of flow, which was undetectable with grayscale sonography alone.

700

• Primary PV thrombosis may be 1st sign of hypercoagulable (prothrombotic) condition

Portal Vein Occlusion

Synonyms • Portal vein thrombosis (PVT)

Definitions • Acute, chronic, or neoplastic occlusion of portal vein (PV) due to thrombosis or tumor invasion • Chronic PV occlusion with numerous periportal collaterals is referred to as "cavernous transformation"

IMAGING General Features • Best diagnostic clue ○ Low-attenuation thrombus in PV on CECT ○ On MR and power Doppler – Absence of blood flow or flow void in PV □ May be caused by slow flow in portal hypertension – Nonvisualization of PV (chronic occlusion) – Cavernous transformation of PV (collateralization in porta hepatis) • Location ○ May involve any portion of intra- or extrahepatic PV

CT Findings • CECT of acute thrombosis ○ Arterial phase (25-40 seconds post bolus injection) – High attenuation within involved hepatic lobe or segment due to arterioportal shunting □ Transient hepatic attenuation difference (THAD) ○ Venous phase (60-70 seconds post bolus injection) – Equilibration of hepatic contrast enhancement – Visualization of low-density thrombus ○ Nonocclusive thrombosis: Low-density thrombus partially filling PV lumen ○ Occlusive thrombosis: Low-density thrombus filling PV lumen – Extent variable: May include major intrahepatic branches, splenic vein, superior mesenteric vein (SMV) – Congested (nonoccluded) mesenteric veins upstream from thrombus, mesenteric edema, bowel wall thickening from venous congestion – Ileus, ascites, and splenomegaly may be seen • CECT of chronic PV thrombosis ○ Chronic occlusion (cavernous transformation) of PV – Numerous periportal collateral veins along usual course of PV – Peripancreatic and gallbladder wall varices are common ○ Nonvisualization of PV &/or splenic vein – Thrombosed vein becomes fibrotic "cord" not visible on imaging ○ Well-developed portosystemic collaterals – e.g., splenorenal shunt; esophageal, periumbilical varices ○ Associated findings – Splenomegaly – Atrophy/hypertrophy complex □ Usual pattern is hypertrophy of central (deep) segments, atrophy of peripheral segments

□ May impart lobulated or rounded contour to liver – Increased hepatic artery size &/or flow • CECT of PV tumor invasion ○ Lumen of vein may be expanded by thrombus – Main PV > 23 mm diameter ○ Variable degree of contrast enhancement of intraluminal tumor thrombus – Linear enhancing "threads and streaks" □ Best seen on arterial phase of biphasic CECT – Primary tumor usually visible in hepatic parenchyma or pancreas, often in direct contiguity with thrombus – Commonly seen in hepatocellular carcinoma – Less common in pancreatic carcinoma, cholangiocarcinoma, endocrine tumor of pancreas, metastases

Liver

TERMINOLOGY

MR Findings • T1WI ○ High-signal filling defect • T2WI ○ High-signal acute or tumor thrombus • T2* GRE ○ PV tumor enhances avidly, especially on GRE sequences • T1WI C+ FS ○ Liver parenchyma supplied by thrombosed veins may enhance avidly in arterial phase due to increased hepatic artery flow – Transient hepatic intensity difference (THID) ○ Subacute thrombus hyperintense on T1 and T2 due to methemoglobin ○ Tumor thrombus on enhanced MR – Analogous to CECT (expanded lumen, enhancing thrombus, contiguous with tumor)

Ultrasonographic Findings • Grayscale ultrasound ○ Acute – Echogenic or anechoic clot ○ Subacute – Isoechoic clot • Color Doppler ○ Lack of flow within PV more evident on color Doppler ○ Tumor vessels usually visible within tumor thrombus ○ Partial thrombosis – Filling defect within PV ○ Cavernous transformation – Numerous venous collaterals in porta hepatis – Large collaterals may be mistaken for patent PV ○ Neoplastic invasion of PV – Pulsatile arterial waveforms with reversed flow

Imaging Recommendations • Best imaging tool ○ Color Doppler US initially: Highly accurate and cost effective ○ CECT or MR for comprehensive evaluation • Protocol advice ○ Color and spectral Doppler US ○ Contrast-enhanced CT or MR

701

Liver

Portal Vein Occlusion ○ Most common in patients with cirrhosis ± HCC

DIFFERENTIAL DIAGNOSIS Streaming Artifact • Low-attenuation pseudothrombus due to uneven mixing of blood during PV inflow • PV fills during later scans (equilibrium)

Extrinsic Compression • Mass effect on PV from porta hepatis nodes, hepatic or pancreatic mass

Budd-Chiari Syndrome • Thrombosis of hepatic (not portal) veins ± IVC • Central hepatic sparing and hypertrophy, peripheral atrophy and necrosis

PATHOLOGY

Demographics • Age ○ May occur at any age

Natural History & Prognosis • Nonocclusive PV thrombosis may lyse with no residual or minor PV scarring • Occlusive PV thrombosis = permanent PV occlusion ○ Portal hypertension morbidity (gastrointestinal hemorrhage) from gastroesophageal varices ○ Reduced hepatic blood flow, possible tissue death, regeneration • PV tumor invasion is associated with poor outcome ○ Precludes transplantation and resection; limits chemoembolization

General Features

Treatment

• Etiology ○ Uncommon: Most often associated with hepatic cirrhosis and pancreatitis ○ Thrombosis – Stasis from cirrhosis-related sinusoidal obstruction – Acute pancreatitis □ Propagation of clot from splenic vein to PV – Septic thrombophlebitis □ From diverticulitis, appendicitis, intraperitoneal abscess, inflammatory bowel disease – Hypercoagulable (prothrombotic) states ○ Tumor invasion – Hepatocellular carcinoma (HCC) most common – Pancreatic ductal or neuroendocrine carcinoma – Liver metastases, cholangiocarcinoma are rare causes of PVT • Associated abnormalities ○ Liver abscess with septic thrombophlebitis ○ Hepatic tumors (e.g., HCC) with neoplastic invasion

• Anticoagulation for acute bland thrombosis (if liver function permits) • Systemic antibiotics for septic thrombophlebitis

Staging, Grading, & Classification

2.

• Portal vein invasion by hepatic (or pancreatic) cancer has much worse prognosis than same size tumor without tumor thrombus

DIAGNOSTIC CHECKLIST Consider • Distinguish between tumor and bland thrombus in setting of cirrhosis

Image Interpretation Pearls • Enhancing thrombus contiguous with parenchymal tumor = tumor thrombus

Reporting Tips • Thrombosis or fibrosis of extrahepatic PV may complicate or preclude liver transplantation

SELECTED REFERENCES 1.

3.

4.

Microscopic Features • Tumor invasion of PV from HCC shows histologic features of primary tumor

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Liver dysfunction ○ Abdominal pain due to bowel congestion, ileus, or infarction • Other signs/symptoms ○ Possible ascites ○ Incidental finding on imaging study: Common in advanced cirrhosis ○ May be initial presentation of hypercoagulable condition – Resulting altered liver morphology and dysfunction may be mistaken for cirrhosis • Clinical profile 702

5. 6.

7.

Girleanu I et al: Natural course of nonmalignant partial portal vein thrombosis in cirrhotic patients. Saudi J Gastroenterol. 20(5):288-292, 2014 Francoz C et al: Portal vein thrombosis, cirrhosis, and liver transplantation. J Hepatol. 57(1):203-12, 2012 Gaba RC: Chemoembolization practice patterns and technical methods among interventional radiologists: results of an online survey. AJR Am J Roentgenol. 198(3):692-9, 2012 Tublin ME et al: Altered liver morphology after portal vein thrombosis: not always cirrhosis. Dig Dis Sci. 53(10):2784-8, 2008 Maconi G et al: Portal vein thrombosis in inflammatory bowel diseases: A single-center case series. J Crohns Colitis. 6(3):362-7, 2012 Qi X et al: Degree of portal vein thrombosis might be associated with recanalization during anticoagulation. Clin Gastroenterol Hepatol. 10(7):820, 2012 Rodríguez-Castro KI et al: Optimal length of anticoagulant therapy in cirrhotic patients with portal vein thrombosis. Clin Gastroenterol Hepatol. 10(7):820-1, 2012

Portal Vein Occlusion Liver

(Left) Axial CECT of a 59-yearold man with cirrhosis shows an occluded portal vein with cavernous transformation of the portal vein and extensive varices as a result. (Right) CT section in the same patient shows varices in and around the wall of the gallbladder that might mimic primary gallbladder disease. Gallbladder wall varices occur almost exclusively in patients with portal vein thrombosis and cavernous transformation.

(Left) CT section in the same patient shows extensive varices within the hepatoduodenal ligament. (Right) CT section in the same patient shows a mass of varices in and around the pancreatic head that might be mistaken for a hypervascular tumor of the pancreas.

(Left) Axial CECT of a 55-yearold man with cirrhosis and bleeding gastric varices shows "bland" (not malignant) thrombosis of the portal vein , a cirrhotic liver, and huge upper abdominal varices . (Right) Axial arterial phase CECT of a 28-year-old man recovering from a gunshot wound to the abdomen shows hyperenhancement of the anterior right lobe segments of the liver, a THAD due to septic thrombophlebitis, and occlusion of the anterior branch of the right portal vein .

703

Liver

Portal Vein Occlusion

(Left) Axial CECT of a 32-yearold woman with bleeding esophageal varices but no history of liver disease shows no patent portal vein and only a few small collaterals . The spleen is surgically absent following prior episodes of splenic infarction. (Right) CT section in the same patient shows the occluded portal vein and large collateral veins . Note the dysmorphic liver, with hypertrophy of the central liver and atrophy of the periphery, giving it rounded contours.

(Left) CT section shows the venous collaterals and the dysmorphic liver. This is a typical case of primary portal vein thrombosis. This may be mistaken clinically and on imaging for cirrhosis, but it has a very different etiology, therapeutic implications, and prognosis. This patient was subsequently confirmed to have a prothrombotic condition (protein S deficiency). (Right) CT section shows more of the collateral veins in the mesentery due to primary portal vein thrombosis.

(Left) Arterial phase CECT of a 59-year-old woman with portal vein thrombosis due to a prothrombotic condition shows thrombus of the posterior branch of the right portal vein. Compensatory increased flow through the hepatic artery accounts for the THAD in the posterior right lobe. (Right) Portal venous phase CECT in the same patient shows uniform enhancement of the liver, the thrombosed right portal vein , and ascites .

704

Portal Vein Occlusion Liver

(Left) Axial CECT late arterial phase image demonstrates hyperenhancement of the anterior right lobe of the liver due to thrombosis of the anterior branch of the right portal vein. Note the thrombosed intrahepatic branches that might be mistaken for dilated bile ducts. (Right) Axial CECT in the same patient shows hyperdensity of the anterior right lobe of the liver and an enlarged right hepatic artery that is compensating for the decreased flow through the portal vein.

(Left) Arterial phase CECT of a 63-year-old man with hepatitis C and HCC shows distention of the left, right, and main portal veins by enhancing tumor thrombus . The primary hepatic tumors are difficult to identify since most of the tumor is within the portal veins rather than the parenchyma . (Right) Arterial phase CECT in the same case shows the diameter of the veins is increased and tumor vascularity is evident within the thrombus, particularly within the main portal vein .

(Left) The parenchymal and portal vein tumors are somewhat easier to recognize as contiguous structures on the coronal-reformatted arterial phase CECT in the same case. (Right) Axial venous phase CECT in the same case shows the parenchymal tumors as hypodense structures relative to hepatic parenchyma due to contrast washout from the HCC, a characteristic feature of this tumor. Tumor within the portal veins showed the same finding on other sections (not shown).

705

Liver

Passive Hepatic Congestion KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Stasis of blood within liver parenchyma as result of impaired hepatic venous drainage

• Budd-Chiari syndrome • Hepatic cirrhosis • Acute viral hepatitis

IMAGING • CECT ○ Early retrograde enhancement of dilated inferior vena cava (IVC) and hepatic veins (HVs) ○ Heterogeneous, mottled, reticulated, mosaic hepatic parenchymal pattern ○ Periportal low attenuation (perivascular lymphedema) ○ Hepatomegaly and ascites • US: Loss of normal triphasic flow pattern ○ Spectral signal may have "M" shape ○ Cardiac cirrhosis: Flattening of Doppler wave form in hepatic veins ○ "To and fro" motion in hepatic veins and IVC

(Left) Graphic shows massive diffuse dilatation of the hepatic veins and mildly heterogeneous liver parenchyma due to passive congestion of the liver. (Right) Axial CECT in the arterial phase shows early retrograde opacification of dilated hepatic veins and the inferior vena cava (IVC) due to reflux of injected contrast medium through the heart, a sign of impaired antegrade hepatic venous drainage.

(Left) Increased pulsatility of portal vein Doppler signal is demonstrated in this patient with passive hepatic congestion secondary to tricuspid insufficiency. (Right) Transverse ultrasound shows dilated hepatic veins and IVC in a patient with passive hepatic congestion.

706

CLINICAL ISSUES • Passive hepatic congestion usually secondary to ○ Congestive heart failure ○ Constrictive pericarditis ○ Tricuspid insufficiency ○ Right heart failure • Diagnosis is based on clinical and imaging findings

DIAGNOSTIC CHECKLIST • Differentiate acute passive hepatic congestion from BuddChiari and viral hepatitis • Distinguish chronic, cardiac cirrhosis from other etiologies

Passive Hepatic Congestion

Synonyms

DIFFERENTIAL DIAGNOSIS

• Congested liver in cardiac disease

Budd-Chiari Syndrome

Definitions

• Narrowed IVC or hepatic veins and ascites • Dysmorphic liver with ascites, collateral veins

• Stasis of blood within liver parenchyma as result of impaired hepatic venous drainage

IMAGING General Features • Best diagnostic clue ○ Dilated hepatic veins with "to and fro" blood flow on color Doppler US • Key concepts ○ Hepatic manifestations of cardiac disease – Acute manifestation: Enlarged, heterogeneous liver – Late manifestation: Cardiac cirrhosis, small liver that may resemble cirrhosis of other causes

CT Findings • Early retrograde enhancement of dilated inferior vena cava (IVC) and hepatic veins (HVs) ○ Due to contrast reflux from right atrium into IVC • Heterogeneous, mottled hepatic parenchymal pattern on arterial &/or venous phase CECT ○ Due to delayed enhancement of smaller hepatic veins • Periportal low attenuation (perivascular lymphedema) • Hepatomegaly and ascites • Chest findings vary by type of cardiac disease ○ Small heart due to constrictive pericarditis ○ Cardiomegaly due to valvular heart disease or cardiomyopathy ○ ± pericardial or pleural effusions

MR Findings • T2WI ○ Periportal high signal intensity (periportal edema) • T1WI C+ ○ Same dilated IVC and HVs as seen on CECT ○ Mottled hepatic enhancement

Ultrasonographic Findings • Grayscale ultrasound ○ Dilated IVC and hepatic veins, hepatomegaly, ± ascites ○ Diameter of hepatic vein: Normal is 5 or 6 mm – Passive congestion: HV diameter of 8-13 mm • Color Doppler ○ Spectral velocity pattern (IVC and HVs) – Loss of normal triphasic flow pattern – Spectral signal may have "M" shape – Cardiac cirrhosis: Flattening of Doppler wave form in hepatic veins – "To and fro" motion in HVs and IVC ○ Increased pulsatility of portal venous Doppler signal

Imaging Recommendations • Best imaging tool ○ Color Doppler sonography; MR to evaluate nature of cardiac disease • Protocol advice

Liver

○ Biphasic CT or MR to evaluate extent of liver damage

TERMINOLOGY

Hepatic Cirrhosis • Small nodular liver with signs of portal hypertension • HVs: Normal caliber and flow pattern

Acute Viral Hepatitis • Hepatic and portal veins: Normal caliber and flow pattern

PATHOLOGY General Features • Etiology ○ Congestive heart failure ○ Constrictive pericarditis ○ Pericardial effusion ○ Tricuspid or pulmonary valve disease ○ Cardiomyopathy • Clinical and imaging signs of cardiac disease

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Enlarged and tender liver, RUQ pain due to stretched liver capsule ○ Hepatic failure may be diagnosed before cardiac disease – e.g., may be misdiagnosed as "cryptogenic cirrhosis" when due to constrictive pericarditis ○ Diagnosis based on clinical and imaging findings • Clinical profile ○ Cardiac patient with hepatomegaly and hepatojugular reflux

Natural History & Prognosis • Complications: hepatic &/or cardiac failure • Prognosis: good for acute congestion ○ Chronic phase: Poor

DIAGNOSTIC CHECKLIST Consider • Differentiate acute passive hepatic congestion from BuddChiari and viral hepatitis • Distinguish chronic, cardiac cirrhosis from other etiologies

SELECTED REFERENCES 1. 2. 3. 4. 5.

Heller MT et al: Imaging of acute conditions affecting the hepatic vasculature. Emerg Radiol. 19(4):329-39, 2012 Saliba T et al: Hepatocellular carcinoma in two patients with cardiac cirrhosis. Eur J Gastroenterol Hepatol. 22(7):889-91, 2010 Ariyarajah V et al: The utility of cardiovascular magnetic resonance in constrictive pericardial disease. Cardiol Rev. 17(2):77-82, 2009 Torabi M et al: CT of nonneoplastic hepatic vascular and perfusion disorders. Radiographics. 28(7):1967-82, 2008 Tani I et al: MR imaging of diffuse liver disease. AJR Am J Roentgenol. 174(4):965-71, 2000

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Liver

Passive Hepatic Congestion

(Left) Oblique transabdominal ultrasound of a 63-year-old woman with RUQ pain shows circumferential gallbladder wall edema and shadowing posterior to a gallstone . (Right) Axial US image of the hepatic confluence in the same case shows marked dilatation of the retrohepatic IVC and hepatic veins .

(Left) In the same case, Doppler interrogation of the right hepatic vein shows markedly phasic flow. (Right) Doppler of the main portal vein in the same case shows pulsatile portal venous flow. US findings of dilated IVC and hepatic veins (HVs), gallbladder wall edema, markedly phasic HV flow, and pulsatile portal venous flow are classic findings that indicate passive hepatic congestion and are key in distinguishing this (rather than acute cholecystitis) as the diagnosis.

(Left) Arterial phase CECT in a 57-year-old man with recent myocardial infarction shows marked reflux of contrast material down into the dilated HVs and IVC . (Right) Portal venous CT in the same case shows HVs lower in the liver are not yet opacified by antegrade flow through the liver. The liver is enlarged and parenchymal enhancement is diminished and very heterogeneous, sometimes described as a "nutmeg liver."

708

Passive Hepatic Congestion Liver

(Left) Axial arterial phase CECT of a 63-year-old woman initially diagnosed with "cryptogenic cirrhosis" shows reflux of contrast material into dilated HVs and the IVC . A right-sided pleural effusion is also present. (Right) Arterial phase CECT section in the same case shows heavier, contrast-opacified blood settling within the dependent position of the dilated IVC and even the right renal vein .

(Left) Axial venous phase CECT in the same case shows bilateral pleural effusions and a thickened, calcified pericardium that compresses and distorts both the right and left ventricles, consistent with constrictive pericarditis. (Right) Venous phase CECT in the same case shows dilation of the IVC . The liver is diminished in size with a nodular surface.

(Left) Venous phase CECT in the same case shows layering of contrast-opacified blood within the dilated IVC, indicating severe restriction of venous return to the heart. (Right) Venous phase CECT in the same case shows a nodular hepatic surface and widened fissures. This patient had constrictive pericarditis suggested for the first time based on CT interpretation, which was subsequently confirmed. The chronic passive congestion of the liver had resulted in cardiac cirrhosis.

709

Liver

Budd-Chiari Syndrome KEY FACTS

TERMINOLOGY • Global or segmental hepatic venous outflow or IVC obstruction

IMAGING • Characteristic findings: Nodular regenerative hyperplasia in a dysmorphic liver with venous collateral and ascites • CECT and MR show hypertrophied caudate lobe with atrophy and necrosis of peripheral liver ○ May simulate a large neoplasm within caudate lobe • Intrahepatic and systemic venous collaterals bypass obstructed hepatic veins and IVC ○ Spider web pattern of hepatic venous collaterals on CT, MR, angiography • Large regenerative nodules (form of nodular regenerative hyperplasia) are characteristic of chronic BCS ○ Imaging and histology similar to FNH ○ May have peripheral halo and central scar

(Left) Axial anatomic illustration of Budd-Chiari syndrome demonstrates ascites, venous collaterals , heterogeneous hepatic parenchyma due to centrilobular necrosis, and hypervascular regenerative nodules . Note the sparing of the caudate lobe with hypertrophy , as well as the thrombosed IVC. (Right) Axial CECT shows caudate hypertrophy, a large caudate collateral vein , and peripheral atrophy and heterogeneity. The hepatic veins were occluded.

(Left) Transverse color Doppler ultrasound of the liver in a 48-year-old woman with known polycythemia vera, RUQ pain, and elevated liver function tests reveals a lack of flow within the right hepatic vein . (Right) Color Doppler ultrasound in the same patient demonstrates a large intrahepatic collateral vein bypassing the occluded hepatic veins.

710

○ Hypervascularity persists into venous phase without washout ○ Uniform or peripheral delayed retention (bright) on gadoxetate-enhanced MR • Absent, reversed, or flat flow in hepatic veins; reversed flow in IVC on color Doppler US

PATHOLOGY • Etiology in western populations is usually a hypercoagulable condition

DIAGNOSTIC CHECKLIST • Do not mistake BCS for cirrhosis ○ Pathogenesis, imaging findings, prognosis, and treatment are very different • Do not mistake caudate hypertrophy or large regenerative nodules for hepatocellular carcinoma • Check for hypercoagulable conditions, prior chemotherapy, or bone marrow transplant

Budd-Chiari Syndrome

Abbreviations • Budd-Chiari syndrome (BCS)

•

Synonyms • Hepatic venous outflow obstruction

•

Definitions • Global or segmental hepatic venous outflow obstruction ○ At level of large hepatic veins or suprahepatic segment of inferior vena cava (IVC)

•

IMAGING General Features • Best diagnostic clue ○ Caudate hypertrophy, peripheral atrophy, ascites, and collateral veins bypassing occluded IVC • Location ○ Hepatic veins, IVC, or centrilobular veins • Characteristic finding: Nodular regenerative hyperplasia in a dysmorphic liver

CT Findings • NECT ○ Acute phase – Diffusely hypodense enlarged liver – Narrowed IVC and hepatic veins; ascites – Hyperdense IVC and hepatic veins (due to increased attenuation of thrombus) ○ Chronic phase – Heterogeneous hypodensity and atrophy of peripheral liver □ Hypertrophy of caudate lobe, which is spared □ Caudate often greater in diameter than right lobe □ Normal caudate to right lobe is 0.6 (60%) – Nonvisualization of IVC and hepatic veins • CECT ○ Acute phase – Classic "flip-flop" pattern seen □ Early enhancement of caudate lobe and central portion around IVC, decreased peripheral liver enhancement □ Later decreased enhancement centrally with increased enhancement peripherally – Narrowed hypodense hepatic veins and IVC with hyperdense walls ○ Chronic phase – Total obliteration of IVC and hepatic veins – Large regenerative nodules: Focal, multiacinar form of nodular regenerative hyperplasia □ Enhancing 1-4 cm hyperdense nodules, ± hypodense ring, ± central scar □ Usually multiple • CTA ○ Hepatic venous outflow obstruction

MR Findings • T1WI ○ Increased intensity of liver centrally with peripheral heterogeneity

•

○ Narrowed or absent hepatic veins and IVC ○ Hyperintense regenerative nodules and enlarged caudate lobe T2WI ○ Nonvisualized hepatic veins and IVC ○ Iso- or hypointense regenerative nodules T2* GRE ○ No demonstrable flow in hepatic veins or IVC T1WI C+ ○ Tumor thrombus (rare) may show enhancement ○ Acute phase – Damaged parenchyma enhances less than surrounding liver ○ Congested liver with increased water content – Peripheral liver enhances < central liver, secondary to parenchymal pressure, blood supply ○ Chronic phase – Enhancement is more variable, may be increased – Nodules: Intense enhancement that persists into venous phase (no washout) – Uniform or peripheral delayed retention, bright on gadoxetate-enhanced MR MRA ○ Depicts thrombus and level of venous obstruction

Liver

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Hepatic veins narrowed, nonvisualized, or filled with thrombus ○ Hypertrophied caudate lobe • Color Doppler ○ Hepatic veins and IVC – Absent or flat flow in hepatic veins – Reversed flow in hepatic veins or IVC – "Bicolored" hepatic veins due to intrahepatic collateral pathways – Sensitivity: 87.5% ○ Portal vein – Slow hepatofugal flow 11 cm/s ○ Hepatic artery: Resistive index 0.75

Angiographic Findings • Inferior venacavography or hepatic venacavography ○ Spider web pattern of hepatic venous collaterals ○ Thrombus in hepatic veins or IVC ○ Long segmental compression or stenosis of IVC – Acute phase: Due to diffuse hepatomegaly – Chronic phase: Hypertrophy of caudate lobe ○ Hepatic arteries – Acute phase: Narrowing, stretching, bowing – Chronic phase: Dilated with arterioportal shunts

Imaging Recommendations • Best imaging tool ○ Multiphasic CT or MR

DIFFERENTIAL DIAGNOSIS Hepatic Cirrhosis • Hypertrophy: Caudate and lateral segment of left lobe • Atrophy: Right lobe and medial segment of left lobe 711

Liver

Budd-Chiari Syndrome

• Portosystemic varices, rather than intrahepatic and body wall collaterals • Patent hepatic veins and IVC • Cirrhotic regenerative nodules ○ Usually small in size compared to nodules in Budd-Chiari ○ Cirrhotic nodules often have increased iron – Usually hypovascular, decreased signal on T2WI ○ Vascular masses in cirrhosis are often hepatocellular carcinoma (HCC); washout on venous phase

PATHOLOGY General Features • Etiology ○ Primary: Venous outflow membranous obstruction – Controversial etiology – Congenital, injury, or infection – Rarely encountered in western populations ○ Secondary: Thrombotic, rarely nonthrombotic – Obstruction of central and sublobular veins □ Chemotherapy and radiation – Obstruction of major hepatic veins □ Hypercoagulable states (e.g., oral contraceptives, polycythemia, protein C deficiency) □ This is the dominant cause and type of BCS – Obstruction of small centrilobular veins (venoocclusive disease) □ Bone marrow transplantation, antineoplastic drugs – Nonthrombotic: Hepatic and extrahepatic masses

Gross Pathologic & Surgical Features • Acute phase ○ Congested enlarged liver with occlusion of hepatic veins and IVC • Chronic phase ○ Shrunken nodular liver; may be cirrhotic ○ Hypertrophied caudate lobe, atrophy of other lobes ○ Extensive collateral veins

Microscopic Features • Centrilobular congestion, dilated sinusoids • Fibrosis, necrosis, cell atrophy

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute phase: Rapid onset RUQ pain, tender liver, hypotension ○ Chronic phase: RUQ pain, hepatomegaly, splenomegaly, jaundice, ascites, varices • Lab data ○ Acute – Liver function tests: Mildly to markedly increased – Hypercoagulable ○ Chronic – Transaminases: Normal or moderately increased – Albumin and prothrombin: Decreased

Demographics • Age ○ Onset typically occurs in young adulthood 712

• Gender ○ M 0.75) ○ Abnormal portal vein wave form ○ Small caliber hepatic veins

(Left) Complete obliteration of the central vein accompanied by centrizonal sinusoidal congestion is seen in venoocclusive disease (VOD). (Courtesy S. Kakar, MD.) (Right) Endothelial swelling with subendothelial edema and fibrosis led to partial occlusion of the lumen of a small hepatic vein in venoocclusive disease. (Courtesy S. Kakar, MD.)

(Left) Axial T2WI MR in a 43year-old woman with VOD following chemotherapy with FOLFOX for appendiceal carcinoma shows ascites and periportal edema , which are nonspecific findings. Liver biopsy showed sinusoidal congestion and fibrotic venules. (Right) Axial contrastenhanced T1WI MR in the same patient shows the ascites and periportal edema .

716

CLINICAL ISSUES • Acute onset of painful hepatomegaly, jaundice, ascites within 3 weeks following hematopoietic or stem cell transplantation • Occurs most frequently following HCT (affects 50-80% of recipients) • Similar disease may occur following exposure to various toxic agents ○ Chemotherapy ○ Liver transplantation • Treatment ○ Antithrombotic and thrombolytic medication

Venoocclusive Disease

Abbreviations • Hepatic venoocclusive disease (VOD)

Synonyms • Hepatic sinusoidal obstruction syndrome (preferred)

Definitions • Hepatic venous outflow obstruction due to occlusion of terminal hepatic venules and sinusoids

IMAGING CT Findings • Same general findings as on US (hepatomegaly, ascites, etc.)

MR Findings • Ascites and periportal edema, both bright (hyperintense) on T2WI

Ultrasonographic Findings • Sensitivity and specificity of imaging findings are low • Overlap those of graft vs. host disease (GVHD) ○ Hepatosplenomegaly; ascites ○ Periportal and gallbladder wall edema ○ Hepatofugal flow on Doppler; resistive index (> 0.75) ○ Abnormal portal vein wave form ○ Small caliber hepatic veins

Imaging Recommendations • Best imaging tool ○ Ultrasound provides suggestive evidence of VOD; helps exclude other diagnoses (e.g., opportunistic infection)

DIFFERENTIAL DIAGNOSIS Opportunistic Infection, Hepatic • Hematopoietic (or stem) cell transplantation (HCT) patients are at risk for hepatic infections • Multifocal small lesions with enhancing rims suggest fungal (e.g., Candida) or mycobacterial microabscesses

Graft-vs.-Host Disease • Primarily a clinical diagnosis, characterized by acute hepatic injury ( bilirubin + transaminases), skin rash, and gastrointestinal disease (diarrhea, hematochezia) • No specific hepatic imaging characteristics to distinguish from VOD

• Progressive venular obstruction, centrilobular hemorrhagic necrosis • Progressive deposition of collagen, fibrosis vascular lumina

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute onset of painful hepatomegaly, jaundice, ascites within 3 weeks following hematopoietic or stem cell transplantation ○ Weight gain • Other signs/symptoms ○ Signs and symptoms of liver failure – Ascites, encephalopathy, etc.

Demographics • Gender ○ Women affected more than men

Natural History & Prognosis • Occurs most frequently following hematopoietic cell transplantation ○ Affects 50-80% of marrow transplant, stem cell, or umbilical cord blood recipients ○ Responsible for 5-15% of deaths in this population • Similar disease may occur following exposure to various toxic agents ○ Chemotherapy, alkaloid toxins, radiation therapy, liver transplantation

Treatment • Antithrombotic and thrombolytic medication

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Imaging (usually US) can suggest diagnosis of VOD and help exclude other causes of hepatic dysfunction among HCT recipients

SELECTED REFERENCES 1. 2.

3. 4.

Budd-Chiari Syndrome • Thrombosis or obstruction at level of larger hepatic veins or IVC • Different etiology (hypercoagulable states); pathogenesis; imaging features • Not related to bone marrow transplantation

5.

6.

7.

PATHOLOGY Microscopic Features

Liver

TERMINOLOGY

8.

Gao H et al: Definitive diagnosis of hepatic sinusoidal obstruction syndrome induced by pyrrolizidine alkaloids. J Dig Dis. 13(1):33-9, 2012 Jevtic D et al: Veno-occlusive disease in pediatric patients after hematopoietic stem cell transplantation: relevance of activated coagulation and fibrinolysis markers and natural anticoagulants. J Pediatr Hematol Oncol. 33(3):227-34, 2011 Lin G et al: Hepatic sinusoidal obstruction syndrome associated with consumption of Gynura segetum. J Hepatol. 54(4):666-73, 2011 Mahgerefteh SY et al: Radiologic imaging and intervention for gastrointestinal and hepatic complications of hematopoietic stem cell transplantation. Radiology. 258(3):660-71, 2011 Menke J: Education and imaging. Hepatobiliary and pancreatic: sinusoidal obstruction syndrome during chemotherapy. J Gastroenterol Hepatol. 26(6):1083, 2011 Sanei MH et al: Acute cellular rejection resulting in sinusoidal obstruction syndrome and ascites postliver transplantation. Transplantation. 92(10):1152-8, 2011 Sebagh M et al: Significance of isolated hepatic veno-occlusive disease/sinusoidal obstruction syndrome after liver transplantation. Liver Transpl. 17(7):798-808, 2011 Rubbia-Brandt L: Sinusoidal obstruction syndrome. Clin Liver Dis. 14(4):65168, 2010

• Injury to hepatic venous endothelium • Progresses to deposition of fibrinogen + factor VIII within venule, sinusoidal walls 717

Liver

Hepatic Infarction KEY FACTS

IMAGING

PATHOLOGY

• Best diagnostic clue: Peripheral, wedge-shaped, lowattenuation areas with absent or heterogeneous enhancement • Lesions may have geographic segmental distribution with straight margins • Lesions more conspicuous after enhancement (perfusion defects) • Best imaging tool: Triphasic CECT with CT angiography • Catheter angiography may be necessary for diagnosis and treatment

• Hepatic infarction is rare due to dual blood supply from hepatic artery and portal vein, extensive collateral pathways

TOP DIFFERENTIAL DIAGNOSES

• New focal liver lesion with branching pattern in transplant patient with deteriorating function suggests infarction • Preservation of portal tracts helps differentiate infarction from abscess, biloma, or post-biopsy hematoma

• • • •

Focal steatosis Hepatic abscess Hepatic trauma Focal steatosis

(Left) Axial CECT image obtained in a 64-year-old woman who presented with RUQ pain and fever for 3 days after hemicolectomy for cecal carcinoma demonstrates a large wedge-shaped area of nonenhancement due to infarction. (Right) Axial CECT in the same patient shows gas within infarcted liver tissue. The gas in the infarcted tissue was secondary to nitrogen gas release, not infection.

(Left) Axial CECT of a 63-yearold woman with autoimmune "connective tissue disease" and sudden RUQ pain shows a massive hypodense lesion throughout the right lobe of the liver, with normal hepatic blood vessels coursing through it, suggesting that this is not a tumor. (Right) CT in the same patient shows active bleeding on arterial phase. At surgery a necrotic right lobe of liver was resected. No tumor or other specific lesion was found, and the infarction was attributed to hypercoagulability and vasculitis.

718

CLINICAL ISSUES • Serious complication of liver transplantation ○ May be due to occlusion of hepatic artery &/or portal vein ○ May require retransplantation

DIAGNOSTIC CHECKLIST

Hepatic Infarction

Synonyms • Liver infarction

Definitions • Area of coagulation necrosis due to local ischemia resulting from obstruction of circulation, most commonly by thrombus or embolus

IMAGING General Features • Best diagnostic clue ○ Peripheral, wedge-shaped, low-attenuation areas with absent or heterogeneous enhancement • Size ○ Variable: Often segmental or lobar

CT Findings • NECT ○ Wedge-shaped, rounded, ovoid, or irregularly shaped low-attenuation areas parallel to bile ducts – Acute: Poorly demarcated, low-density lesions – Subacute: Confluent, more distinct margins ○ ± gas formation within sterile or infected infarcts ○ Bile lakes seen as late sequela – Especially in liver transplant setting – Hepatic artery thrombosis biliary and hepatic necrosis • CECT ○ Lesions may have geographic, segmental distribution with straight margins ○ Lesions more conspicuous after enhancement (as perfusion defects) ○ Heterogeneous patchy enhancement represents ischemic parenchyma ○ Some lesions remain hypodense on arterial, portal venous, and delayed phases – Necrotic tissue, hemorrhage, or fibrous tissue with no or minimal revascularization on histology ○ Some lesions isoenhance with surrounding liver parenchyma on portal venous phase – Retained viable tissue or fibrotic tissue with revascularization

Ultrasonographic Findings

Liver

TERMINOLOGY

• Grayscale ultrasound ○ Native liver – Early: Hypoechoic lesion with indistinct margins (edema, round cell infiltration) – Small bile duct cysts, large bile duct lakes (necrotic tissue resorption) ○ Liver allograft – Hypoechoic, geographic areas, preservation of portal tracts (early ischemia) – Transient small hyperechoic lesions (progression to true infarction) • Color Doppler ○ HA thrombosis: Absence of normal HA signal – Much more common than portal vein (PV) thrombosis ○ Portosystemic shunting, collateral supply

Nuclear Medicine Findings • Hepatobiliary scan ○ Peripheral, wedge-shaped, sharply defined lesion ○ Communication with bile lakes in post-transplant infarcts • Technetium sulfur colloid: Photopenic area • Cholescintigraphy: Communication with bile lakes in posttransplant infarcts

Imaging Recommendations • Best imaging tool ○ Triphasic CECT with CT angiography – CTA valuable to detect HA thrombosis ○ Real-time B-mode and Doppler US: Evaluate allograft dysfunction, postoperative complications ○ CT/MR angiography can be diagnostic – Catheter angiography is usually reserved for planned intervention (e.g., thrombolysis) • Protocol advice ○ Multiphasic CT (arterial, venous, delayed) ± CT angiography – MR and MRA can be done instead of CT – MR is better than CT in distinguishing steatosis from infarction ○ Catheter angiography may be necessary for diagnosis and treatment

DIFFERENTIAL DIAGNOSIS

MR Findings

Focal Steatosis

• T1WI ○ Infarcted tissue is hypointense – Foci of gas are hypointense • T2WI ○ Infarcted tissue is heterogeneously hyperintense • T1WI C+ ○ Heterogeneous or absent parenchymal enhancement ○ Necrotic areas predominantly hypointense compared with enhancing parenchyma in arterial, portal venous, and delayed phases ○ Gadoxetate- (Eovist, Primovist) enhanced scan – May see accumulation of contrast-opacified bile on delayed imaging – Especially in setting of liver transplantation with hepatic artery (HA) thrombosis and biliary necrosis

• May be geographic, wedge shaped • Preserved patent-enhancing vessels within "lesion" • Characteristic suppression of signal from abnormal tissue on opposed-phased GRE MR

Hepatic Abscess • Usually spherical, often septate • Central nonenhancing contents, enhancing rim

Hepatic Trauma • Jagged low-attenuation areas of laceration • Subcapsular hematoma compresses lateral contour • Hepatic trauma may cause infarction by disrupting arterial and portal venous flow to liver segment

719

Liver

Hepatic Infarction

General Features • Etiology ○ Iatrogenic – Cholecystectomy, hepatobiliary surgery, intrahepatic chemoembolization □ May cause occlusion of hepatic artery – Transjugular intrahepatic portosystemic shunt (TIPS) procedure ○ Liver transplantation: HA stenosis/thrombosis ○ Blunt trauma: HA, portal vein lacerations ○ Hypercoagulable states – Sickle cell anemia, antiphospholipid antibody syndrome, etc. ○ Vasculitis: Polyarteritis nodosa, lupus, etc. ○ Infection: Rare emphysematous hepatitis; follows sepsis and shock – Usually in diabetic patient – Analogous to emphysematous pyelonephritis ○ Pregnancy with hemolytic anemia, elevated liver enzymes, low platelets (HELLP) syndrome – Usually complication of eclampsia or pre-eclampsia • Hepatic infarction is rare due to dual blood supply from HA and PV, extensive collateral pathways • Infarction of native liver usually requires occlusion or narrowing of both HA and portal vein • HA thrombosis in liver allograft more likely to lead to infarction (collateral supply is severed during transplant) ○ Biliary necrosis usually precedes hepatic necrosis as bile ducts are totally dependent on arterial flow

Gross Pathologic & Surgical Features • Multiple, focal, necrotic areas; peripheral collapse of parenchymal tissue with fibrosis

Microscopic Features • Central congestion, centrilobular necrosis surrounded by hemorrhagic rims • Infarcted nodules have central core of amorphous eosinophilic material (remnants of necrotic hepatocytes) ○ Cells with foamy cytoplasm (macrophages) surround necrotic core ○ Ultimate replacement by fibrovascular tissue

CLINICAL ISSUES

Natural History & Prognosis • Parenchymal atrophy and scarring, progressive liquefaction; affects center of hepatic lobule most prominently; relative sparing of portal end • Serious complication of liver transplantation; significant morbidity and mortality ○ Often requires retransplantation • Complications ○ Native liver: Liver failure, fibrosis ○ Transplanted liver: Biliary strictures, bilomas, abscess ○ Renal failure, coma

Treatment • Revascularization, retransplantation, spontaneous resolution

DIAGNOSTIC CHECKLIST Consider • Pre-TIPS evaluation of arterial supply to liver by Doppler/angiography • Post-TIPS: Watch for RUQ pain, fever, shock, disseminated intravascular coagulation • Infarction is among spectrum of pregnancy-related liver disorders (part of HELLP syndrome); avoid delay in diagnosis and treatment • Ischemia alone may show sonographic features of infarction; may be reversible with early diagnosis

Image Interpretation Pearls • Preservation of portal tracts helps differentiate infarction from abscess, biloma, or post-biopsy hematoma • New focal liver lesion with branching pattern in transplant patient with deteriorating function suggests infarction ○ Due to HA thrombosis or stenosis

SELECTED REFERENCES 1.

2.

3.

Presentation

4.

• Most common signs/symptoms ○ Asymptomatic, nonspecific: RUQ or back pain, fever ○ Massive infarction: Jaundice, ascites • May be complication of HA angiography or embolization • Lab data: Leukocytosis, abnormal liver function tests

5.

Demographics • Age ○ Any age group • Gender ○ M=F • Epidemiology ○ Hepatic infarction uncommon 720

○ HA thrombosis following liver transplant reported in 3% of adults, 12% of children

PATHOLOGY

6.

7.

Chou MM et al: Extensive hepatic infarction in severe preeclampsia as part of the HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets): evolution of CT findings and successful treatment with plasma exchange therapy. Taiwan J Obstet Gynecol. 51(3):418-20, 2012 Cho SK et al: Ischemic liver injuries after hepatic artery embolization in patients with delayed postoperative hemorrhage following hepatobiliary pancreatic surgery. Acta Radiol. 52(4):393-400, 2011 Choi SH et al: Hepatic arterial injuries in 3110 patients following percutaneous transhepatic biliary drainage. Radiology. 261(3):969-75, 2011 Ebert EC et al: Gastrointestinal and hepatic manifestations of rheumatoid arthritis. Dig Dis Sci. 56(2):295-302, 2011 Ebert EC et al: Gastrointestinal and hepatic manifestations of systemic lupus erythematosus. J Clin Gastroenterol. 45(5):436-41, 2011 Letoublon C et al: Hepatic arterial embolization in the management of blunt hepatic trauma: indications and complications. J Trauma. 70(5):1032-6; discussion 1036-7, 2011 Shah PA et al: Hepatic gas: widening spectrum of causes detected at CT and US in the interventional era. Radiographics. 31(5):1403-13, 2011

Hepatic Infarction Liver

(Left) Axial CECT following blunt trauma shows no enhancement of the anterior right lobe of the liver. The hepatic artery to this segment was transected with acute extravasation . (Right) Axial CECT of a 72-year-old man who developed severe RUQ pain and abnormal liver function on awakening from cardiac surgery shows massive foci of nonenhancement of the liver parenchyma , involving all lobes of the liver. This patient died soon after the CT scan.

(Left) Axial CECT in a 57-yearold man 1 week post cholecystectomy shows an hepatic infarction due to the surgical disruption of hepatic arterial flow. Note the hypoattenuation of the left lobe of the liver with a linear, geographic distribution . (Right) Axial CECT at a more inferior level in the same patient shows surgical clips within the course of the left hepatic artery and patchy hypoattenuation in the right hepatic lobe .

(Left) Thick, axial reconstructed CECT following liver transplantation shows the hepatic artery is thrombosed at the anastomosis with a large liver infarction of the allograft. The rest of the allograft is presumably still perfused by the portal vein, but biliary and hepatic necrosis developed soon afterward. (Right) Celiac arteriogram in the same patient shows the lack of arterial blood supply to the allograft with occlusion of the hepatic artery at the anastomosis.

721

Liver

Peliosis Hepatis KEY FACTS

TERMINOLOGY • Rare benign disorder characterized by sinusoidal dilation and presence of multiple blood-filled lacunar spaces within liver

IMAGING • May be diffuse or focal within liver • Portal phase: Centrifugal or centripetal enhancement without mass effect on hepatic vessels • Delayed phase: Late, diffuse, homogeneous hyperattenuation • Hyperintense on T2WI ○ Multiple foci of signal due to presence of subacute blood (hemorrhagic necrosis)

TOP DIFFERENTIAL DIAGNOSES • Hepatic adenoma ○ Differentiate from peliosis by pattern of contrast enhancement on triphasic CT and dynamic MR

(Left) Axial NECT in a 42-yearold woman with diabetes, chronic renal failure, and failed renal transplantation shows a mass that is nearly isodense with blood vessels. The ascites is due to peritoneal dialysis. (Right) Axial arterial phase CECT in the same patient shows a solid peripheral ring of bright enhancement unlike the nodular pattern that is typical of hemangiomas.

(Left) Axial portal venous phase CECT in the same patient shows progressive centripetal "fill in" of the mass. Because of its atypical features, the mass was biopsied and found to be peliosis. The etiology of peliosis is often obscure, but diabetes and renal transplantation are 2 conditions that have been associated with it. (Right) Transverse color Doppler ultrasound in the same patient shows a hyperechoic liver mass without prominent vascularity. The hepatic veins are not compressed.

722

• Hepatic cavernous hemangioma ○ Enhancement similar to peliosis but discontinuous nodular or globular for hemangioma; continuous ring for peliosis • Focal nodular hyperplasia • Hypervascular metastases • Presence of fatty contents helpful in establishing diagnosis of adenoma

PATHOLOGY • Associated with chronic wasting diseases and other chronic illnesses, steroid medications, and oral contraceptives • After renal or cardiac transplantation • Bacillary peliosis hepatis caused by Bartonella infection in patients with AIDS

CLINICAL ISSUES • Regression after drug withdrawal, cessation of steroid therapy, resolution of associated infectious disease

Peliosis Hepatis

Abbreviations

○ Strong contrast enhancement with branching appearance; caused by vascular component on fatsuppressed T1 delayed imaging

• Peliosis hepatis (PH)

Ultrasonographic Findings

Synonyms

• Grayscale ultrasound ○ Heterogeneous hepatic echopattern with hyper/hypoechoic regions – Homogeneous hypoechoic lesions □ In patients with steatosis – Heterogeneous hypoechoic □ Complicated with hemorrhage – Hyperechoic patterns □ In patients with normal liver – May show slow turbulent flow on color Doppler

• Hepatic peliosis

Definitions • Rare benign disorder characterized by sinusoidal dilation and presence of multiple blood-filled lacunar spaces within liver

IMAGING General Features • Best diagnostic clue ○ Spherical lesion with centrifugal or centripetal enhancement • Location ○ May be diffuse or focal within liver ○ Other affected organs: Spleen, bone marrow, lymph nodes, lungs, pleura, kidneys, adrenals, stomach, ileum • Size ○ Varies from 1 mm to several centimeters • Key concepts ○ Irregularly shaped, blood-filled hepatic cavities

Angiographic Findings

CT Findings

• Best imaging tool ○ Multiphasic CECT or MR

• NECT ○ Multiple hepatic areas of low attenuation ○ Findings differ with size of lesions, presence or absence of thrombus within cavity, and presence of hemorrhage – If peliotic cavities are < 1 cm in diameter, CT findings may appear normal • CECT ○ Larger cavities communicating with sinusoids have same attenuation as blood vessels ○ Thrombosed cavities appear as nonenhancing nodules ○ Arterial phase: Early globular, vessel-like enhancement – Multiple small accumulations of contrast; hyperdense in center or periphery of lesion ○ Portal phase: Centrifugal or centripetal enhancement without mass effect on hepatic vessels ○ Delayed phase: Late diffuse homogeneous hyperattenuation characteristic of phlebectatic type

MR Findings • T1WI ○ Hypointense ○ signal due to presence of subacute blood suggestive of hemorrhagic necrosis • T2WI ○ Hyperintense ○ Multiple foci of signal due to presence of subacute blood (hemorrhagic necrosis) • T1WI C+ ○ Lesions usually show contrast enhancement in pattern similar to CECT ○ Cystic cavity with enhancing rim represents hematoma

Liver

TERMINOLOGY

• Conventional ○ Multiple nodular, vascular lesions; accumulations of contrast material on late arterial phase – ± simultaneous opacification of hepatic veins – More prominent during parenchymal phase and persist on venous phase – Angiographic evaluation may be diagnostic in difficult cases

Imaging Recommendations

DIFFERENTIAL DIAGNOSIS Hepatic Adenoma • Might be associated with long-term use of estrogen • Differentiate from peliosis by pattern of contrast enhancement on triphasic CT and dynamic MR • Presence of fatty contents is helpful in establishing diagnosis of adenoma • Completely hyperdense in arterial phase, becoming isodense to liver in portal phase (uncommon) • Biopsy is often necessary

Hepatic Cavernous Hemangioma • Typical enhancement pattern (peripheral enhancement with centripetal progression) • Enhancement similar to peliosis but discontinuous nodular or globular for hemangioma; continuous ring for peliosis • Larger lesions produce mass effect on hepatic vessels

Focal Nodular Hyperplasia • Homogeneous hypervascular mass on arterial phase; isodense to liver on portal and delayed phases ○ Central scar with attenuation on arterial and portal phases and enhancement on delayed images

Hypervascular Metastases • Usually totally hypodense or isodense in delayed phase because of rapid washout of contrast material

Pyogenic Abscess, Hepatic • Important to differentiate from peliosis to avoid percutaneous drainage of peliotic lesions, which can be dangerous or fatal • Pyogenic abscess 723

Liver

Peliosis Hepatis ○ Multiseptated mass, "cluster of grapes" appearance ○ Nonenhancing contents ○ Typical clinical presentation, sepsis

PATHOLOGY General Features • Etiology ○ Bacillary PH is caused by Bartonella infection in HIVpositive patients and other immunosuppressed patients ○ Congenital angiomatous malformation is an established cause in minority of patients ○ No clear etiology or associated disease in up to 50% of PH cases ○ Pathogenesis remains uncertain; possible theories include – Outflow obstruction at sinusoidal level – Hepatocellular necrosis cyst formation – Dilation of a portion of central vein of hepatic lobule – Direct lesions of sinusoidal barrier ○ Zones of peliosis may be seen within hepatic adenoma, hepatocellular carcinoma, and angiosarcoma • Associated abnormalities ○ Associated with chronic wasting diseases – TB, leprosy, malignancy (e.g., hepatocellular carcinoma), AIDS ○ Other chronic illnesses: Celiac disease, diabetes, vasculitis, hematological disorders ○ After renal or cardiac transplantation – Usually results in only microscopic peliosis ○ Medications – Anabolic steroids, corticosteroids, tamoxifen, oral contraceptives, diethylstilbestrol, azathioprine

Gross Pathologic & Surgical Features • Irregularly shaped, blood-filled hepatic cavities

Microscopic Features • Cystic dilated sinusoids filled with red blood cells and bound by cords of liver cells • Phlebectatic type: Endothelial-lined, blood-filled spaces and aneurysmal dilatation of central vein and sinusoids • Parenchymal type: Not lined by endothelium and usually associated with hemorrhagic parenchymal necrosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic ○ Other signs/symptoms – ± hepatomegaly, ascites, portal hypertension – Lymphadenopathy with Bartonella henselae and neurological symptoms with Bartonella quintana bacillary PH • Other signs/symptoms ○ Peliotic lesions may rupture hemoperitoneum ○ Patients with bacillary PH may have fever, abdominal pain, lymphadenopathy

Demographics • Age 724

○ Fetal life (rare) to adult life • Gender ○ M=F • Epidemiology ○ Peliosis is rare entity ○ Increasing incidence of cases of bacillary peliosis and angiomatosis in immunocompromised patients

Natural History & Prognosis • Regression after drug withdrawal, cessation of steroid therapy, resolution of associated infectious disease • Pseudotumoral and hemorrhagic evolution • Complications: Liver failure, cholestasis, portal hypertension, liver rupture shock ○ May be rapidly fatal if untreated

Treatment • Options, risks, complications ○ Withdrawal of inciting agents ○ Surgical resection of involved liver section ○ Resolves spontaneously (uncommon) ○ Clinical improvement with antibiotics (erythromycin or doxycycline) in HIV-related PH caused by B. henselae

DIAGNOSTIC CHECKLIST Consider • Clinical setting (e.g., AIDS, chronic illness, medications)

Image Interpretation Pearls • Consider peliosis for peculiar hyperenhancing liver lesion failing to fit criteria for other, more common etiologies

SELECTED REFERENCES 1.

Slim R et al: Education and Imaging. Hepatobiliary and pancreatic: peliosis hepatis associated with multiple myeloma. J Gastroenterol Hepatol. 29(1):5, 2014 2. Battal B et al: Multifocal peliosis hepatis: MR and diffusion-weighted MRimaging findings of an atypical case. Ups J Med Sci. 115(2):153-6, 2010 3. Fowell AJ et al: Education and imaging. Hepatobiliary and pancreatic: peliosis hepatis. J Gastroenterol Hepatol. 26(6):1082, 2011 4. Torabi M et al: CT of nonneoplastic hepatic vascular and perfusion disorders. Radiographics. 28(7):1967-82, 2008 5. Tallón García M et al: [Peliosis hepatitis secondary to hormone treatment.] An Pediatr (Barc). 75(4):286-8, 2011 6. Wannesson L et al: Peliosis hepatis in cancer patients mimicking infection and metastases. Onkologie. 32(1-2):54-6, 2009 7. Kim EA et al: Peliosis hepatis with hemorrhagic necrosis and rupture: a case report with emphasis on the multi-detector CT findings. Korean J Radiol. 8(1):64-9, 2007 8. Kim SH et al: Focal peliosis hepatis as a mimicker of hepatic tumors: radiological-pathological correlation. J Comput Assist Tomogr. 31(1):79-85, 2007 9. Pitassi LH et al: Bartonella henselae infects human erythrocytes. Ultrastruct Pathol. 31(6):369-72, 2007 10. Tsirigotis P et al: Peliosis hepatis following treatment with androgen-steroids in patients with bone marrow failure syndromes. Haematologica. 92(11):e106-10, 2007

Peliosis Hepatis Liver

(Left) Axial venous phase CECT in a 42-year-old woman with a 25-year history of oral contraceptive use shows multiple hypodense lesions with enhanced periphery. (Right) Axial T2WI MR in the same patient shows a hyperintense lesion in the left lobe corresponding to one of the lesions seen on CT. The other liver lesions had a similar appearance and partially resolved after discontinuation of contraceptives. Ultrasoundguided biopsy proved peliosis hepatis.

(Left) Axial arterial phase CECT shows an incidentally discovered mass with no early enhancement. (Right) Axial portal venous phase CECT in the same patient shows the mass with central enhancement almost isodense to blood vessels. On delayed images (not shown), the mass "filled in" centrifugally, unlike the centripetal pattern typical of hemangioma. Because of its atypical appearance, the mass was biopsied and found to represent peliosis. No associated disease or etiology was established.

(Left) Axial CECT in a patient with peliosis and AIDS shows multiple hypodense hepatic lesions with peripheral enhancement. A similar lesion is present in the spleen as well. These were due to Bartonella infection and resolved following antibiotic therapy. This is known as bacillary peliosis hepatis. (Right) Axial CECT in the same patient shows extensive brightly enhancing lymphadenopathy as well as additional hypodense lesions in the liver and spleen .

725

Liver

Hereditary Hemorrhagic Telangiectasia KEY FACTS

TERMINOLOGY • Osler-Weber-Rendu syndrome • Hereditary multiorgan disorder resulting in fibrovascular dysplasia with development of telangiectasias and arteriovenous malformations (AVMs)

IMAGING • Color Doppler US is good screening modality for hepatic involvement • CECT or MR: Multiplanar and angiographic reconstructions depict complex hepatic vascular alterations ○ Large, tortuous extrahepatic ± intrahepatic arteries with early filling and enlargement of hepatic ± portal veins ○ Heterogeneous enhancement of hepatic parenchyma ○ Telangiectasias: Small vascular spots – More readily recognizable on reconstructed multiplanar reformatted and MIP images ○ Large, confluent vascular masses

(Left) This graphic shows dilated hepatic veins and arteries with direct intraparenchymal communication through tortuous vascular channels . (Right) Axial CECT shows early filling of dilated hepatic veins and innumerable small tangles of telangiectatic vessels , findings diagnostic of HHT.

(Left) CT section in the same patient shows an enlarged hepatic artery , innumerable small tangles of telangiectatic vessels , and larger vascular masses or pools . These findings are diagnostic of HHT (OslerWeber-Rendu syndrome). (Right) Color Doppler sonography shows tangled masses of enlarged arteries and veins, with vascular malformations bypassing the hepatic sinusoids.

726

– Appear as larger vascular pools (1-3 cm) with early and persistent enhancement during arterial phases

TOP DIFFERENTIAL DIAGNOSES • • • •

Cirrhosis Traumatic intrahepatic arteriovenous fistulas Arteriovenous shunting with tumors Budd-Chiari syndrome

CLINICAL ISSUES • Multiple mucocutaneous telangiectasias with multiorgan involvement ○ Nasal mucosa: Recurrent epistaxis ○ CNS (cerebral or spinal AVM): Seizures, paraparesis, subarachnoid hemorrhage ○ Gastrointestinal: GI bleed and angiodysplasias ○ Pulmonary: Cyanosis, polycythemia, dyspnea, hemoptysis • Diagnostic criteria: Family history, epistaxis, mucocutaneous telangiectasias, AVMs

Hereditary Hemorrhagic Telangiectasia

Abbreviations • Hereditary hemorrhagic telangiectasia (HHT)

Synonyms • Osler-Weber-Rendu syndrome (OWR)

Definitions • Hereditary multiorgan disorder resulting in fibrovascular dysplasia with development of telangiectasias and arteriovenous malformations (AVMs) • Direct connection between arteries and veins with absence of capillaries; telangiectasias are small AVMs

IMAGING General Features • Best diagnostic clue ○ Dilated hepatic and portal veins and arteries with direct intraparenchymal communication through tortuous vascular channels • Location ○ Skin, lungs, liver, mucus membranes, gastrointestinal tract, and brain

CT Findings • CECT ○ Large, tortuous extrahepatic ± intrahepatic arteries with early filling and enlargement of hepatic ± portal veins ○ Heterogeneous enhancement of hepatic parenchyma – Due to arteriovenous shunting – May see transient hepatic attenuation difference (THAD) lesions □ Wedge-shaped peripheral regions of hyperenhancement on arterial phase images – Hepatic parenchyma usually homogeneous on venous/parenchymal phase of imaging ○ Telangiectasias: Small vascular spots; more readily recognizable on reconstructed multiplanar reformatted and MIP images – 5-7 mm; look like asterisks on CECT – Found in 2/3 of affected patients ○ Large, confluent, vascular masses – Appear as larger vascular pools (1-3 cm) with early and persistent enhancement during arterial phases – These are large shunts or multiple telangiectases that have coalesced – Found in 1/4 of affected patients ○ ± focal bile duct dilatation (external compression) ○ Uncommon involvement of pancreas and spleen ○ GI tract involvement may cause GI bleeding from submucosal telangiectasias

• T1WI C+ ○ Telangiectasias: Small, homogeneously enhancing ○ Early enhancement of peripheral portal veins and wedge-shaped transient parenchymal enhancement during hepatic arterial phase (THID lesions) ○ Dynamic gradient echo after Gd-DTPA for analysis of filling kinetics • MRA ○ Depicts map of anomalous vessels (number and size of feeding arteries and draining veins) ○ Time between early arterial phase and enhancement of malformation used to distinguish high- and low-flow lesions – High-flow AVMs show early, intense enhancement – Venous malformations: Either not visible or show late enhancement of veins

Liver

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Good screening modality for hepatic involvement ○ Dilated hepatic arteries, multiple arteriovenous malformations, and abnormal hepatic echogenicity • Pulsed Doppler ○ High hepatic artery velocities = 153 ± 65.2 cm/s ○ Hepatic artery to portal vein shunts cause pulsatility of portal flow with phasic or continuous reversal ○ Hepatic artery to hepatic vein shunts show significant changes in Doppler waveform of hepatic vein – Only in severe stages of disease • Color Doppler ○ Tangled masses of enlarged tortuous arteries or multiple aneurysms of hepatic arteriole branches within liver

Angiographic Findings • Usually not indicated if CTA or MRA is available • Conventional ○ Tortuous, dilated, hepatic arterial branches ○ Numerous irregular areas of dense contrast accumulation throughout liver parenchyma ○ Diffuse angioectasias and diffuse mottled capillary blush ○ Early filling of enlarged hepatic ± portal veins

Imaging Recommendations • Best imaging tool ○ Color Doppler as noninvasive screening modality ○ CECT or MR with multiplanar and angiographic reconstructions depict complex hepatic vascular alterations typical of HHT • Protocol advice ○ CTA with axial and coronal MIP images; include arterial and parenchymal phase images

DIFFERENTIAL DIAGNOSIS

MR Findings

Cirrhosis

• T1WI ○ Telangiectasias: Hypo- to isointense • T2WI ○ Network of vessels with flow voids on spin echo • STIR ○ Best for extent of malformations – MRA alone may underestimate extent

• "Corkscrew" appearance produced by combination of in arterial flow and regenerative nodules • Transsinusoidal arterioportal shunting in advanced cirrhosis; intrasegmental hepatofugal portal flow • Does not result in multiple, widespread focal vascular lesions or transient parenchymal heterogeneity • HHT does not cause nodular liver surface or lobar atrophy 727

Liver

Hereditary Hemorrhagic Telangiectasia

Traumatic Intrahepatic Arteriovenous Fistulas • Causes: Biopsy, transhepatic biliary drainage, blunt or penetrating injury, rupture of hepatic aneurysm into portal vein • Usually isolated site of dilatation of feeding artery, early opacification of draining vein, and poor visualization of artery distal due to fistula stealing blood

Arteriovenous Shunting Within Tumors • With hepatomas and metastatic tumors, shunting suggests venous invasion by tumors

Budd-Chiari Syndrome (BCS) • Obstruction of hepatic venous outflow; collateral channels develop between hepatic, portal, and systemic venous systems • CT: Heterogeneous parenchymal density with periportal and peripheral enhancement, caudate lobe enlargement • BCS results in small or occluded hepatic veins ○ HHT enlarged hepatic &/or portal veins

PATHOLOGY General Features • Etiology ○ Genes encoding a protein that binds transforming growth factor • Genetics ○ Autosomal dominant trait with high penetrance and great heterogeneity ○ HHT phenotypes – HHT1: Mutations at chromosome 9 (ENG gene) alter protein endoglin – HHT2: Mutations at chromosome 12 (ACVRL gene) alter protein actinin or ALK1 • Associated abnormalities ○ Pulmonary AVMs are more likely to cause symptoms and complications in patients with HHT

Gross Pathologic & Surgical Features • Hepatic angiodysplastic vascular changes include ○ Telangiectasias, cavernous hemangiomas, aneurysm of intraparenchymal branches of hepatic artery, and intraparenchymal, hepatoportal, and arteriovenous fistulas

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Some are asymptomatic; anemia due to recurrent bleeds ○ Multiple mucocutaneous telangiectasias with multiorgan involvement – Nasal mucosa: Recurrent epistaxis – CNS (cerebral or spinal AVM): Seizures, paraparesis, subarachnoid hemorrhage – Gastrointestinal: GI bleed and angiodysplasias – Pulmonary: Cyanosis, polycythemia, dyspnea on effort, clubbing, bruit ○ Liver: Often asymptomatic; rarely causes parenchymal fibrosis, biliary ischemia, liver failure – Hepatic parenchyma: Fibrosis, atypical cirrhosis, chronic active hepatitis (rare) 728

• Clinical profile ○ Diagnostic criteria: Family history, epistaxis, mucocutaneous telangiectasias, AVMs

Demographics • Age ○ Onset: Adult life; hepatic involvement diagnosed 10-20 years after 1st appearance of telangiectasias • Gender ○ M=F • Epidemiology ○ 10-20:100,000

Natural History & Prognosis • Complications: High-output congestive heart failure, portal hypertension, hepatic portosystemic encephalopathy, biliary ischemia, and liver failure ○ With extrahepatic involvement: Hemoptysis, hemothorax, cerebrovascular accident, cerebral abscess • Prognosis: Usually good

Treatment • Supportive: Iron/blood transfusion • Hepatic arterial coil embolization, surgical ligation of hepatic artery, liver transplantation

DIAGNOSTIC CHECKLIST Consider • Due to high prevalence of pulmonary and cerebral AVMs, all patients with HHT should be screened • Relatives of patients with HHT should be investigated for presence of disease

SELECTED REFERENCES 1. 2.

3.

4.

5. 6. 7.

8.

Gaujoux S et al: Liver resection in patients with hepatic hereditary hemorrhagic telangiectasia. Dig Surg. 30(4-6):410-4, 2013 Barral M et al: Hepatic and pancreatic involvement in hereditary hemorrhagic telangiectasia: quantitative and qualitative evaluation with 64section CT in asymptomatic adult patients. Eur Radiol. 22(1):161-70, 2012 Dupuis-Girod S et al: Bevacizumab in patients with hereditary hemorrhagic telangiectasia and severe hepatic vascular malformations and high cardiac output. JAMA. 307(9):948-55, 2012 Buscarini E et al: Natural history and outcome of hepatic vascular malformations in a large cohort of patients with hereditary hemorrhagic teleangiectasia. Dig Dis Sci. 56(7):2166-78, 2011 McDonald J et al: Hereditary hemorrhagic telangiectasia: an overview of diagnosis, management, and pathogenesis. Genet Med. 13(7):607-16, 2011 Sekarski LA et al: Hereditary hemorrhagic telangiectasia: children need screening too. Pediatr Nurs. 37(4):163-8; quiz 169, 2011 Siddiki H et al: Abdominal findings in hereditary hemorrhagic telangiectasia: pictorial essay on 2D and 3D findings with isotropic multiphase CT. Radiographics. 28(1):171-84, 2008 Song X et al: Individualized management of hepatic diseases in hereditary hemorrhagic telangiectasia. Am Surg. 77(3):281-5, 2011

Hereditary Hemorrhagic Telangiectasia Liver

(Left) Arterial phase CECT of a 31-year-old man with hepatic dysfunction, nosebleeds, and hemoptysis shows large arteriovenous malformations (AVMs) in the right lung base . The liver has a mottled enhancement pattern with premature filling of dilated hepatic veins . (Right) CT in the same patient shows discrete AVMs within the liver in addition to the smaller and less clearly defined telangiectasias and mottling of the parenchyma.

(Left) In the same patient, discrete AVMs are seen within the liver, in addition to the mottling of the parenchyma, and massive enlargement of the hepatic arteries is noted . (Right) This CT section in the same patient shows massive enlargement of the hepatic artery and mottled enhancement of the hepatic parenchyma.

(Left) This CT section in the same patient shows an arterioportal shunt in addition to the huge hepatic artery . (Right) The coronal volume-rendered reconstruction of the CT in this patient demonstrates the pulmonary AVMs . Hereditary hemorrhagic telangiectasia (Osler-WeberRendu syndrome) is a hereditary disorder that results in fibrovascular dysplasia with the potential to develop telangiectasias and AVMs within many organs, most commonly the skin, lungs, liver, and GI tract.

729

Liver

Hereditary Hemorrhagic Telangiectasia

(Left) An arterial phase CT image of a 32-year-old woman with personal and family histories of nosebleeds shows heterogeneous enhancement of the hepatic parenchyma and early filling of enlarged hepatic veins . (Right) Arterial phase CT in the same patient shows heterogeneous enhancement of the hepatic parenchyma, early filling of the enlarged hepatic veins and IVC, and enlarged, tortuous hepatic arteries .

(Left) Axial portal venous (hepatic parenchymal) CECT in the same patient looks normal except for the dilated hepatic veins and IVC, indicating that the intrahepatic shunting of blood accounted for the heterogeneous early phase appearance of the parenchyma. (Right) Venous phase CT in this patient shows 1 of 2 hypodense masses of unknown etiology that have remained stable in size over several years.

(Left) Catheter angiography in the same patient shows the dilated arterial branches, numerous irregular areas of dense parenchymal enhancement, and innumerable angioectasias. (Right) Catheter angiography in the same patient shows early filling of enlarged veins . Catheter angiography is rarely needed to confirm the extent of HHT and has largely been replaced by CTA and MRA.

730

Hereditary Hemorrhagic Telangiectasia Liver

(Left) Axial CECT of a 47-yearold man with high-output heart failure due to HHT shows that the liver has a very mottled enhancement with enormous dilation of the hepatic veins , which are opacified prematurely. (Right) CT section in the same patient shows a huge hepatic artery and diffuse telangiectasias and AVMs throughout the liver, bypassing the sinusoids and accounting for the poor enhancement of the parenchyma.

(Left) A peculiar feature in this patient was the presence of heterogeneously hypoenhancing hepatic lesions . (Right) An MR scan was obtained in this patient for further evaluation and confirmed the hypovascular nature of these focal lesions with no evidence of neoplasm.

(Left) Axial CT of an 82-yearold woman with known HHT and new onset of fever and RUQ pain shows typical findings of HHT, including mottled enhancement and focal AVMs . There is a focal mass that contains gas. (Right) Axial CECT in the same patient shows a "pigtail" catheter that was introduced by CT guidance to drain the abscess .

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Liver

HELLP Syndrome KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Hemolysis, elevated liver enzymes, low platelets (HELLP) • Severe variant of preeclampsia

• Acute epigastric and RUQ pain ○ 90% of cases • 1-2 per 1,000 live births; 10-20% of eclamptic patients • Clinical profile ○ African American female, primigravida, features of preeclampsia and lab data positive for hemolysis, elevated liver enzymes, and low platelets • Classic triad of preeclampsia ○ Hypertension, proteinuria, edema

IMAGING • Best diagnostic clue ○ Intrahepatic or subcapsular fluid collection (hematoma) on US or CT • CT not ideal due to radiation dose, but may be necessary in severe cases • US: Irregular or wedge-shaped liver hemorrhage or infarct with increased echogenicity; usually peripheral

TOP DIFFERENTIAL DIAGNOSES • • • •

Acute fatty liver of pregnancy Hepatic trauma Spontaneous hemorrhage (coagulopathy) Bleeding hepatic tumor (adenoma or HCC)

(Left) This is a transverse grayscale ultrasound image of a 39-year-old woman who presented with sharp RUQ and right pleuritic pain during her 3rd trimester of pregnancy. Laboratory values revealed markedly decreased platelets, consistent with HELLP syndrome. Note the mass effect on the liver from a predominantly hypoechoic subcapsular hematoma . (Right) Longitudinal grayscale ultrasound image obtained in the same patient again shows the peripheral subcapsular hematoma .

(Left) This 35-year-old woman had toxemia and sudden RUQ pain with falling hematocrit. Axial CECT shows a massive subcapsular and perihepatic hematoma along with active bleeding and heterogeneous enhancement of the hepatic parenchyma . (Right) A selective hepatic arteriogram shows multiple foci of active hemorrhage , which were treated with coil embolization. Following the birth of twins shortly after the angiogram, the patient made a complete recovery.

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DIAGNOSTIC CHECKLIST • In hypotensive patient, look for and embolize active bleeding • Rarely can occur without classic preeclampsia triad

HELLP Syndrome Liver

○ Indicated when there is concern for hepatic rupture or hemorrhage (e.g., hypotension, right shoulder pain)

TERMINOLOGY Abbreviations

DIFFERENTIAL DIAGNOSIS

• Hemolysis, elevated liver enzymes, low platelets (HELLP)

Definitions

Bleeding Hepatic Tumor (Adenoma, HCC)

• Severe variant of preeclampsia

• Intraparenchymal or subcapsular fluid collection on US or CT; may bleed • Enhancing heterogeneous spherical hepatic mass • Clinical history should help distinguish

IMAGING General Features • Best diagnostic clue ○ Intrahepatic or subcapsular fluid collection (hematoma) on US, CT, or MR

CT Findings • Liver hematomas ○ Well-defined, hyper- or hypodense, depending on physical state of blood ○ Nonenhancing ○ Acute: Hyperattenuating clot (24-72 hours) ○ Chronic: Decreased attenuation after 72 hours (lysed clot) • Liver infarction ○ Small or large areas of low attenuation, usually peripheral and wedge shaped ○ May be indistinguishable from steatosis of pregnancy • Occasionally active contrast extravasation or ascites ○ Active bleeding is serious; may require embolization or surgery

MR Findings • Hemorrhage and necrosis (often coexist) ○ T1WI and T2WI – T1WI: Low signal intensity – T2WI: High signal intensity – Varied signal intensity based on □ Degree and age of hemorrhage, infarct, or steatosis □ Greater degree of edema and cellular necrosis in infarction

Ultrasonographic Findings • Grayscale ultrasound ○ Irregular or wedge-shaped liver hemorrhage or infarct with increased echogenicity; usually peripheral ○ Periportal halo sign: Hyperechoic thickening of periportal area ○ Subcapsular hematoma: Complex echogenic fluid collection ○ Enlarged liver (predominantly right lobe) ○ Occasionally ascites, may be complex (hemorrhagic) • US features may be seen before increase in biological markers (41% of cases)

Imaging Recommendations • Best imaging tool ○ Ultrasonography is least invasive, often sufficient – Can depict intra- and perihepatic hemorrhage – Limited view of abdomen and pelvis (due to gravid uterus) • Protocol advice ○ MR and CT offer larger field of view

Spontaneous Hemorrhage (Coagulopathy) • Subcapsular or intrahepatic blood collection, occasionally active extravasation • History of bleeding disorder • Lab data: Abnormal bleeding time, clotting time, prothrombin time, and partial thromboplastin time • Indistinguishable from HELLP syndrome without history

Hepatic Trauma • • • • •

History of liver injury Intraparenchymal or subcapsular hematoma Lacerations, wedge-shaped areas of infarction Areas of active hemorrhage isodense with vessels Hemoperitoneum and pseudoaneurysm

Acute Fatty Liver of Pregnancy • Usually diffuse increased echogenicity of liver on US • No intraparenchymal or subcapsular fluid collection (no hemorrhage)

PATHOLOGY General Features • Etiology ○ Variant of severe preeclampsia, occasionally eclampsia ○ Preeclampsia and eclampsia etiology – Coagulation abnormalities, hormonal factors, uteroplacental ischemia, immune mechanisms ○ Pathophysiology of HELLP syndrome: Placental bed origin – Arteriolar vasospasm endothelial damage fibrin deposition – Platelet deposition on fibrin aggregates decreased number of circulating platelets (< 100,000) ○ RBC destruction by fibrin aggregates (hemolytic anemia) – Abnormal cells in peripheral smear (burr cells, schistocytes) – Increased indirect bilirubin levels and anemia ○ Hepatocyte destruction due to hepatic microemboli ( transaminase levels) – Distention of liver due to impeded blood flow (RUQ pain) – Liver rupture, subcapsular hematoma in severe cases ○ Pathophysiology of preeclampsia – Primary site: Increased size of glomerular endothelial cells – Abnormal vasoconstriction and hyperactive vascular smooth muscle – Hypertension proteinuria edema • Associated abnormalities

733

Liver

HELLP Syndrome ○ Disseminated intravascular coagulation (DIC); abruptio placentae; acute renal failure; pulmonary edema

Staging, Grading, & Classification • Based on classification of American College of Obstetricians and Gynecologists ○ Bilirubin: > 1.2 mg/dL ○ Lactate dehydrogenase: > 600 U/L ○ Aspartate aminotransferase: > 70 IU/L ○ Platelet count: < 100,000/mm³

Gross Pathologic & Surgical Features • Enlarged liver, subcapsular hematoma; parenchymal hemorrhage or infarct

Microscopic Features • Periportal necrosis, microthrombi; fibrin deposits in sinusoids and portal veins

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute epigastric and RUQ pain ○ Preeclampsia: Classic triad – Hypertension, proteinuria, edema ○ Eclampsia – Classic triad of preeclampsia – Associated with convulsions, coma ○ Clinical differential diagnoses – Viral hepatitis, gallstones, peptic ulcer – Pancreatitis, acute fatty liver – Hemolytic uremic syndrome – Idiopathic thrombocytopenic purpura • Other signs/symptoms ○ Malaise, nausea, vomiting, weight gain ○ Edema, headache, visual impairment, jaundice • Clinical profile ○ African American female, primigravida with features of preeclampsia and lab data positive for hemolysis, elevated liver enzymes, and low platelets • Lab data ○ Hemoglobin: < 11 g/dL ○ Bilirubin: > 1.2 mg/dL ○ Lactate dehydrogenase: > 600 U/L ○ Aspartate aminotransferase: > 70 U/L ○ Platelet count: < 100,000/mm³

Demographics • Age ○ 2nd and 3rd decades • Gender ○ Female • Ethnicity ○ More frequent in African Americans • Epidemiology ○ Preeclampsia: Leading cause of maternal death in USA and Europe ○ Prevalence of HELLP – 4-12% of patients with severe preeclampsia – 1-2 per 1,000 live births – Toxemia in 6% of pregnancies 734

– HELLP occurs in 10-20% of patients with eclampsia

Natural History & Prognosis • Variant of toxemia in primigravidae ○ Usually preeclampsia, occasionally eclampsia ○ Usually 3rd trimester onset (90%) ○ Occasionally postpartum onset (~ 10%) ○ Rarely seen in multiparous patients • Maternal risk factors ○ Nulliparity, young age, African American ○ Underlying diseases – Hypertension, diabetes, renal disease, hypercoagulable states (e.g., antiphospholipid antibody syndrome) • Complications ○ Rupture of subcapsular hematoma ○ Hepatic necrosis, pulmonary edema, hypoglycemia ○ Disseminated intravascular coagulation ○ Abruptio placentae and renal failure ○ Maternal mortality rate: 3.5% if delayed diagnosis and treatment

Treatment • Standard treatment: Expeditious delivery of fetus • Supportive treatment for most cases • Surgery and selective embolization for hepatic rupture and intraabdominal hemorrhage ○ Rarely, urgent liver transplantation

DIAGNOSTIC CHECKLIST Consider • Rule out bleeding liver tumor (adenoma, HCC) and other liver pathologies

Image Interpretation Pearls • Look for heterogeneous, enhancing, spherical liver tumors • Clinically, can mimic cholecystitis, biliary colic, hepatitis • Rarely, can occur without classic preeclampsia triad

SELECTED REFERENCES 1. 2. 3. 4. 5. 6.

7. 8.

Sadaf N et al: Maternal and foetal outcome in HELLP syndrome at tertiary care hospital. J Pak Med Assoc. 63(12):1500-3, 2013 Heller MT et al: Imaging of hepatobiliary disorders complicating pregnancy. AJR Am J Roentgenol. 197(3):W528-36, 2011 Benedetto C et al: Biochemistry of HELLP syndrome. Adv Clin Chem. 53:85104, 2011 Jank A et al: Effect of steroids on angiogenic factors in pregnant women with HELLP syndrome. J Perinat Med. 39(5):611-3, 2011 Murao K et al: Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome with pituitary apoplexy. Fertil Steril. 96(1):260-1, 2011 Publications Committee et al: Evaluation and management of severe preeclampsia before 34 weeks' gestation. Am J Obstet Gynecol. 205(3):1918, 2011 Nunes JO et al: Abdominal imaging features of HELLP syndrome: a 10-year retrospective review. AJR Am J Roentgenol. 185(5):1205-10, 2005 Araujo AC et al: Characteristics and treatment of hepatic rupture caused by HELLP syndrome. Am J Obstet Gynecol. 195(1):129-33, 2006

HELLP Syndrome Liver

(Left) Transverse sonogram in a 31-year-old woman with toxemia shows a lentiform subcapsular hematoma and heterogeneous hepatic parenchyma , essentially diagnostic of HELLP in this setting. (Right) Axial CT was performed to evaluate for active hemorrhage and shows the large subcapsular hematoma and heterogeneous parenchyma , but no active bleeding nor hemoperitoneum. The patient recovered after delivery without other intervention.

(Left) Axial CECT image obtained in a 27-year-old African American woman in her 3rd trimester of pregnancy under treatment for preeclampsia who presented with sudden onset of RUQ pain and falling hematocrit shows extensive areas of subcapsular hematoma and parenchymal heterogeneity . (Right) Coronal CECT image obtained in the same patient demonstrates marked distortion of the liver from the hematomas in the setting of HELLP syndrome.

(Left) Axial CECT image obtained in a woman during her 3rd trimester of pregnancy demonstrates a massive hemoperitoneum, liver parenchymal hemorrhage, and active bleeding (extravasation of contrast) . (Right) Axial CECT in the same patient illustrates the hemoperitoneum. Note the normal gravid uterus, placenta , and full-term fetus.

735

Liver

Hepatic Trauma KEY FACTS

IMAGING

PATHOLOGY

• Best diagnostic tool: CT evidence of irregular parenchymal lesions with intra- and perihepatic hemorrhage • Location: Right lobe (75%), left lobe (25%) ○ Intraparenchymal &/or subcapsular hematoma ○ Injury to bare area of liver may result in retroperitoneal, not intraperitoneal, bleeding • Best imaging tool: MDCT in hemodynamically stable patients • CT protocol advice: Rapid bolus of contrast; include lung bases and pelvis • Angiography to localize active hemorrhage and embolization to control it

• Blunt trauma is most common cause of hepatic injury

TOP DIFFERENTIAL DIAGNOSES • HELLP syndrome • Spontaneous hemorrhage (coagulopathy) • Bleeding hepatic tumor (e.g., hepatocellular carcinoma or adenoma)

(Left) CT in a 37-year-old man who sustained blunt abdominal trauma in a motor vehicle accident shows a large right lobe hepatic injury (laceration & infarct or parenchymal hematoma) with high-attenuation active arterial extravasation . (Right) Selective right hepatic artery angiogram in the same patient confirms active bleeding , which was successfully treated with a coil embolization. The patient made an uneventful recovery without the need for a blood transfusion.

(Left) Axial CECT obtained in a 19-year-old man who sustained multiple injuries after a motorcycle accident demonstrates a right lobe hepatic laceration with active bleeding . (Right) Axial CECT in the same patient shows extension of active bleeding into the peritoneal cavity along the hepatic capsule. Due to the acute intraperitoneal bleeding, urgent surgery was performed, which revealed an actively bleeding capsular artery.

736

CLINICAL ISSUES • Clinical profile: Patient with history of motor vehicle accident, right upper quadrant tenderness, guarding, and hypotension • Mortality: 10-20% • Liver is 2nd most frequently injured solid intraabdominal organ after spleen

DIAGNOSTIC CHECKLIST • CT evidence of active extravasation ○ Intra- or extrahepatic collection, isodense with vessels ○ Usually indicates need for embolization or surgery, regardless of grade of injury • Laceration of left hepatic lobe is often associated with bowel and pancreatic injury

Hepatic Trauma

Definitions • Liver or hepatic injury

IMAGING General Features • Best diagnostic clue ○ CT evidence of irregular parenchymal lesions with intraand perihepatic hemorrhage • Location ○ Right lobe (75%), left lobe (25%) – Intraparenchymal &/or subcapsular hematoma

CT Findings • Lacerations: Simple or stellate (often parallel to portal/hepatic vein branches) ○ Simple: Hypodense, solitary, linear laceration ○ Stellate: Hypodense, branching, linear lacerations • Parenchymal and subcapsular hematomas (lentiform configuration) ○ Unclotted blood (35-45 HU) soon after injury – NECT: May be hyperdense to normal liver – CECT: Hypodense to enhancing normal liver tissue ○ Clotted blood (60-90 HU) – Hyperdense to unclotted blood and normal liver – May be hyperdense to unenhanced liver – "Sentinel clot" helps to localize source of bleeding • Active hemorrhage or pseudoaneurysm ○ CECT: Active hemorrhage – Isodense to enhanced vessels – Extravasated contrast material (85-350 HU) surrounding low-attenuation clot • Hemoperitoneum: Perihepatic and peritoneal recess blood collections ○ Injury to bare area of liver may result in retroperitoneal, not intraperitoneal, bleeding • Periportal tracking: Linear, focal, or diffuse periportal zones of decreased HU ○ Due to dissecting blood, bile, or dilated periportal lymphatics ○ Differential diagnosis: Overhydration; check for distended inferior vena cava (IVC) – Increased venous pressure and transudation • Areas of infarction ○ Small or large areas of low attenuation ○ Usually wedge-shaped; segmental or lobar ○ Intrahepatic/subcapsular gas (due to hepatic necrosis) ○ May be due to trauma itself or iatrogenic (following surgery or coil embolization for active bleeding) • CT diagnosis of liver trauma ○ Accuracy (96%), sensitivity (~ 100%), specificity (94%)

MR Findings • T1WI and T2WI ○ Varied signal intensity depending on degree/age of hemorrhage or infarct

Ultrasonographic Findings • Grayscale ultrasound

Liver

○ Subcapsular hematoma: Lentiform or curvilinear fluid collection – Initially: Anechoic – After 24 hours: Echogenic – 4-5 days: Hypoechoic – 1-4 weeks: Internal echoes, septations develop within hematoma ○ Intraparenchymal hematoma – Rounded echogenic or hypoechoic foci ○ Bilomas – Rounded/ellipsoid, anechoic, loculated structures – Well-defined sharp margins close to bile ducts ○ Parenchymal tears – Irregular defects – Abnormal echotexture relative to normal liver

TERMINOLOGY

Angiographic Findings • Conventional ○ Active extravasation, pseudoaneurysm ○ Arteriovenous, arteriobiliary, or portobiliary fistulas

Imaging Recommendations • Best imaging tool ○ MDCT in hemodynamically stable patients ○ Angiography to localize active hemorrhage and embolization to control it • Protocol advice ○ MDCT: Include lung bases and pelvis

DIFFERENTIAL DIAGNOSIS HELLP Syndrome • • • • •

Hemolysis, elevated liver enzymes, and low platelets Severe variant of preeclampsia Wedge-shaped areas of infarction Intrahepatic or subcapsular fluid collection (hematoma) Occasionally active extravasation

Spontaneous Hemorrhage (Coagulopathy) • • • •

History of bleeding disorder Lab data: Abnormal hematologic coagulation values Subcapsular or intrahepatic blood collection Indistinguishable from hepatic trauma without history

Bleeding Hepatic Tumor • e.g., hepatocellular carcinoma (HCC) or adenoma • Spherical enhancing parenchymal masses • Vascular, nodal, and visceral invasion common with hepatocellular carcinoma

PATHOLOGY General Features • Etiology ○ Most common causes – Blunt trauma is most prevalent □ Motor vehicle accidents (MVAs) are more common □ Falls and assaults – Penetrating injuries □ Gunshot and stab injuries – Iatrogenic 737

Liver

Hepatic Trauma □ Liver biopsy (most common cause of subcapsular hematoma in USA), chest tubes, transhepatic cholangiography • Associated abnormalities ○ Splenic injury (45%), bowel injury (5%), rib fractures ○ Left hepatic lobe laceration often associated with bowel or pancreatic injury

Staging, Grading, & Classification • Clinical classification based on American Association for the Surgery of Trauma (AAST) ○ Grade I – Subcapsular hematoma: < 10% surface area – Laceration: Capsular tear, < 1 cm parenchymal depth ○ Grade II – Subcapsular hematoma: 10-50% surface area – Intraparenchymal hematoma: < 10 cm diameter – Laceration: 1-3 cm parenchymal depth, < 10 cm length ○ Grade III – Subcapsular hematoma: > 50% surface area; expanding/ruptured subcapsular or parenchymal hematoma – Intraparenchymal hematoma: > 10 cm or expanding – Laceration: Parenchymal fracture > 3 cm deep ○ Grade IV – Laceration: Parenchymal disruption of 25-75% of hepatic lobe or 1-3 Couinaud segments within single lobe ○ Grade V – Laceration: Parenchymal disruption of > 75% of hepatic lobe or > 3 Couinaud segments within single lobe – Vascular: Juxtahepatic venous injuries (retrohepatic vena cava, major hepatic veins) ○ Grade VI – Vascular: Hepatic avulsion

Gross Pathologic & Surgical Features • Subcapsular or intraparenchymal hematoma • Laceration or contusion

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Right upper quadrant (RUQ) pain, tenderness, guarding, rebound tenderness ○ Hypotension, tachycardia, jaundice ○ Hematemesis or melena (due to hemobilia) • Clinical profile ○ Patient with history of MVA, RUQ tenderness, guarding, and hypotension • Lab data ○ Decreased hematocrit (not acutely) ○ Increased direct/indirect bilirubin ○ Increased alkaline phosphatase levels

Demographics • Epidemiology ○ Abdominal trauma – Leading cause of death in USA (< 40 years) 738

– 5-10% of blunt abdominal trauma patients have liver injury – Liver is 2nd most frequently injured solid intraabdominal organ after spleen □ Due to anterior, partially subcostal location

Natural History & Prognosis • Complications ○ Hemobilia, bilomas, arteriovenous fistula, pseudoaneurysm • Prognosis ○ Grades I, II, and III: Good ○ Grades IV, V, and VI: Poor ○ May not necessarily correlate with AAST grading – Presence of active bleeding from liver laceration or other visceral injuries is better prognostic criterion ○ Mortality: 10-20% – 50% due to liver injury itself – Remainder due to associated injuries

Treatment • Grades I, II, and III ○ Conservative management for most injuries diagnosed on CT • Grades IV, V, and VI ○ Surgical intervention for shock, peritonitis – Drainage, repair, control hemorrhage ○ Embolization for active extravasation

DIAGNOSTIC CHECKLIST Consider • Differentiate from HELLP syndrome, spontaneous hemorrhage (coagulopathy), and bleeding hepatic tumors (HCC, adenoma)

Image Interpretation Pearls • CT evidence of active extravasation (intra- or extrahepatic collection, isodense with vessels) usually indicates need for embolization or surgery regardless of injury grade • Laceration of left hepatic lobe is often associated with bowel and pancreatic injury

SELECTED REFERENCES 1.

2.

3. 4. 5.

6. 7.

Orr KE et al: MDCT of retractor-related hepatic injury following laparoscopic surgery: appearances, incidence, and follow-up. Clin Radiol. 69(6):606-10, 2014 Bala M et al: Complications of high grade liver injuries: management and outcome with focus on bile leaks. Scand J Trauma Resusc Emerg Med. 20(1):20, 2012 Li Petri S et al: Surgical management of complex liver trauma: a single liver transplant center experience. Am Surg. 78(1):20-5, 2012 Pachter HL: Prometheus bound: evolution in the management of hepatic trauma--from myth to reality. J Trauma Acute Care Surg. 72(2):321-9, 2012 Cohn SM et al: Computed tomography grading systems poorly predict the need for intervention after spleen and liver injuries. Am Surg. 75(2):133-9, 2009 Cox JC et al: Routine follow-up imaging is unnecessary in the management of blunt hepatic injury. J Trauma. 59(5):1175-8; discussion 1178-80, 2005 Sharma OP et al: Assessment of nonoperative management of blunt spleen and liver trauma. Am Surg. 71(5):379-86, 2005

Hepatic Trauma Liver

(Left) Axial CT in a 33-year-old woman shows displaced rib fractures , subcutaneous gas, and a deep hepatic parenchymal laceration . The injury extends to some large hepatic veins, but no active extravasation is noted. (Right) Axial CECT in the same patient performed 10 days later reveals resolution of the peritoneal blood and substantial healing of the liver laceration. Most patients with hepatic injuries from blunt trauma who are stable enough for CT evaluation can be successfully managed without surgery.

(Left) Axial CECT shows a laceration through the left lobe of the liver . (Right) Axial CECT in the same patient demonstrates a fracture plane through the pancreatic neck extending completely through the gland to the splenic vein, where active bleeding is evident . Injuries to the left lobe of the liver are often associated with injuries to other midline organs.

(Left) Axial CECT shows a linear laceration through the base of the caudate lobe extending to the bare area of the liver and resulting in a retroperitoneal hematoma rather than intraperitoneal bleeding. (Right) Axial CECT shows a large subcapsular hematoma . This patient had been in a recent accident without medical evaluation and self-medicated with aspirin and ibuprofen. Isolated subcapsular hematomas, without intraperitoneal hemorrhage, are uncommon in the setting of trauma.

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Liver

Radiation-Induced Liver Disease KEY FACTS

TERMINOLOGY • Radiation-induced liver disease (RILD): Syndrome characterized by development of anicteric ascites ~ 2 weeks to 4 months after hepatic irradiation

IMAGING • Sharp line of demarcation between normal and abnormal parenchyma corresponds to radiation port or vascular distribution of yttrium-90 microspheres • CT shows sharply defined geographic lesion ○ Vessels within zone may appear normal (no mass effect) ○ Usually low density on NECT and CECT ○ May have mixed hypervascular and hypovascular foci • Region of radiation damage that is hypodense on portal venous phase may become hyperdense with prolonged enhancement on delayed phase ○ Due to vascular perfusion, hepatic venous drainage, and subsequent stasis of contrast medium

(Left) Axial CECT shows a vertically oriented zone of low attenuation extending from the cranial to caudal aspect of the liver in a straight line , following external radiation therapy for lymphoma. (Right) Axial CECT shows a straight line of demarcation of damaged liver in the left lobe due to external radiation therapy for esophageal carcinoma. Note the normal appearance of the left hepatic vein within the zone of radiation-induced liver disease (RILD).

(Left) Axial CECT shows decreased attenuation within the posterior segments of the liver, with a straight line of demarcation corresponding to the segments that had received yttrium-90 microsphere embolization for hepatocellular carcinoma (HCC). Note the normal appearance of the posterior right portal vein within the damaged liver. (Right) CECT section from the same case shows viable satellite foci of HCC within the untreated anterior segments of liver .

740

• MR, especially T1WI with in- and opposed-phase GRE, is best means of distinguishing RILD from steatosis

TOP DIFFERENTIAL DIAGNOSES • Focal steatosis • Hepatic infarction

PATHOLOGY • Patients receiving single 1,200-rad dose of external beam radiation or a 4,000 to 5,500-rad fractionated dose over 6 weeks can develop RILD • Hepatic arterial administration of yttrium-90 glass microspheres ○ Emit radiation to perfused hepatic area persisting for 64hour half-life

CLINICAL ISSUES • Complete clinical recovery typically seen within 60 days, but there may be permanent hepatocyte loss, fat deposition, fibrosis, and obliteration of central veins

Radiation-Induced Liver Disease

DIFFERENTIAL DIAGNOSIS

Abbreviations

Focal Steatosis

• Radiation-induced liver disease (RILD)

• May be geographic, band- or wedge-shaped • Preservation of enhancing vessels within "lesion" • Suppression of signal on opposed-phase GRE MR

Definitions • Syndrome characterized by development of anicteric ascites ~ 2 weeks to 4 months after hepatic irradiation • Form of venoocclusive disease due to fibrous obliteration of terminal hepatic venules postsinusoidal obstruction

IMAGING

Hepatic Infarction • Segmental or geographic hypodense area with straight margins with absent or heterogeneous enhancement

PATHOLOGY

General Features

General Features

• Best diagnostic clue ○ Sharp line of demarcation between normal and abnormal parenchyma corresponds to radiation port or vascular distribution of yttrium-90 microspheres

• Etiology ○ Patients receiving single 1,200-rad dose of external beam radiation or a 4,000 to 5,500-rad fractionated dose over 6 weeks can develop RILD ○ Hepatic arterial administration of yttrium-90 glass microspheres – Emit radiation to perfused hepatic area persisting for 64-hour half-life

CT Findings • NECT ○ Sharply defined band of low attenuation corresponding to treatment port – Probably due to hepatocellular necrosis, edema, and steatosis ○ If hepatic congestion is severe, patchy congestion simulating tumor nodules may be seen ○ In patients with diffuse hepatic steatosis, irradiated area may appear as region of increased attenuation – May be due to loss of fat in irradiated hepatocytes or regional edema ○ Over time, sharp borders of irradiated zone become more irregular and indistinct (peripheral parenchyma regenerates) – Eventually, irradiated area may become atrophic • CECT ○ Enhancement pattern of irradiated liver may vary depending on preexisting hepatic pathology ○ Intense enhancement of irradiated parenchyma may be seen in acute phase injury – Due to arterial flow and reduced portal flow ○ Region of radiation damage that is hypodense on portal venous phase may become hyperdense with prolonged enhancement on delayed phase – Due to vascular perfusion, hepatic venous drainage, and subsequent stasis of contrast medium ○ Narrowing and irregularity of hepatic vessels (sinusoidal congestion and perisinusoidal edema) – Vessels within zone may appear normal (no mass effect)

MR Findings • T1WI ○ Zone of

Liver

TERMINOLOGY

Microscopic Features • Venoocclusive disease • Massive panlobar congestion, hyperemia, hemorrhage, and mild proliferative change in sublobular central veins ○ Stasis secondary to injury of these veins

CLINICAL ISSUES Presentation • Hepatomegaly, ascites, fatigue

Demographics • Epidemiology ○ Now more commonly seen with advent of 3D treatment planning and bone marrow transplantation with total body radiation

Natural History & Prognosis • Complete clinical recovery typically within 60 days ○ Complete resolution or progression to atrophy of involved segments and, rarely, cirrhosis

DIAGNOSTIC CHECKLIST Consider • Factors that influence variability in liver damage ○ Irradiated liver volume, radiation fraction size, cytotoxic agents, and nutritional status

SELECTED REFERENCES 1.

intensity on T1WI,

on T2WI

Imaging Recommendations • Best imaging tool ○ NECT and CECT or MR T1WI GRE with in- and out-ofphase imaging • Protocol advice ○ MR, especially T1WI with in- and opposed-phase GRE, is best means of distinguishing RILD from steatosis

2. 3.

Jung J et al: Radiation-induced liver disease after stereotactic body radiotherapy for small hepatocellular carcinoma: clinical and dose-volumetric parameters. Radiat Oncol. 8:249, 2013 Ng SC et al: Patient dosimetry for 90Y selective internal radiation treatment based on 90Y PET imaging. J Appl Clin Med Phys. 14(5):212-21, 2013 Tao C et al: Improved radiotherapy for primary and secondary liver cancer: stereotactic body radiation therapy. Anticancer Res. 32(2):649-55, 2012

741

Liver

Radiation-Induced Liver Disease

(Left) Arterial phase CECT shows a heterogeneous hypervascular lesion in a 66-year-old man with HCC, prior to the onset of therapy. (Right) Portal venous phase imaging from the same case shows normal-appearing adjacent liver.

(Left) Repeat nonenhanced CT scan during therapy with hepatic arterial infusion of yttrium-90 microspheres shows a wedge-shaped zone of decreased attenuation in the distribution of the right anterior hepatic artery in which the radioactive microspheres had been placed. (Right) An arterial phase CT image from the same study shows persistence of the wedge-shaped zone of radiation-induced liver injury. Note the straight line demarcation of the zone of injury .

(Left) A venous phase CT section from the same study shows that the HCC nodule is less vascular than on pretreatment images. Note persistence of the straight line of demarcation of the treated segment of liver. (Right) Final venous phase CECT section from the same study shows intact blood vessels within the zone of radiation-induced injury. The patient remained clinically asymptomatic with only mild elevation of hepatic transaminase enzymes.

742

Radiation-Induced Liver Disease Liver

(Left) Axial CECT in a 65-yearold man who had radiation therapy for esophageal carcinoma and metastases to the left lobe shows mixed hypo- and hyperdense lesions in the left and caudate lobes, with a straight line of demarcation from normal liver corresponding to the radiation therapy port. (Right) Venous phase CT in the same case shows mixed density lesions in the pattern of the radiation port , not corresponding to any anatomical divisions of the liver, all due to radiation hepatitis.

(Left) Axial CECT in a 26-yearold woman with hepatic metastases from nasopharyngeal carcinoma shows a peculiar lowattenuation band through the center of the liver . Note the lack of mass effect on the large hepatic and portal vein branches traversing this zone. (Right) The same CECT section viewed on bone windows shows 1 of the vertebral metastases that had been treated with external beam radiation therapy.

(Left) Coronal reformatted CT section from the same study shows the band of hypodense liver that represents radiation-induced injury. Again, note the lack of mass effect on vessels within the injured liver, as well as hepatic metastases . (Right) Representative axial CECT section from the same case 4 months later shows resolution of the radiation injury and decreased size of 1 of the hepatic metastases , the latter representing the effects of chemotherapy rather than the radiation therapy.

743

Liver

Postoperative Changes, Liver KEY FACTS

TERMINOLOGY • Iatrogenic changes to hepatic morphology that may cause or simulate pathologic conditions

IMAGING • Gas collection in hepatic or perihepatic lesion or portal vein ○ Consider iatrogenic infarction of hepatic mass or liver parenchyma ○ Consider retained absorbable oxidized cellulose (Surgicel) • Embolized, iodinated, poppyseed oil (Ethiodol, Lipiodol) ○ May mimic calcified or hypervascular mass on plain radiography or CT, respectively • Treated tumor often undergoes progressive volume loss and fibrosis ○ May simulate focal confluent fibrosis, peripheral cholangiocarcinoma, or cirrhosis • Consider prior resection of portions of liver

(Left) Axial CECT shows several viable enhancing liver metastases and 2 masses with gas and necrotic debris that are the result of percutaneous radiofrequency ablation. (Right) Axial CECT shows a collection of gas but very little fluid in the cholecystectomy bed, mimicking an abscess. Note the surgical clips . This is bioabsorbable oxidized cellulose (Surgicel), which was used as a hemostatic agent to control bleeding from the operative bed during cholecystectomy.

(Left) Axial CECT shows an absence of enhancement of the left lobe with a straight line of demarcation and portal venous gas , all due to hepatic arterial ligation during attempted resection of a peripheral cholangiocarcinoma. (Right) Axial CECT shows a metallic coil in the right hepatic artery, with a wedge-shaped collection of gas and fluid "downstream." Needle aspiration and drainage of this collection showed an infected hepatic infarction.

744

○ May have similar appearance to congenital absence or hypoplasia of hepatic segments • Iatrogenic arterioportal (AP) fistula ○ Complication of percutaneous liver biopsy ○ May simulate other vascular lesions, including tumor • Small peripheral AP shunts are common, spontaneous findings in cirrhotic liver

TOP DIFFERENTIAL DIAGNOSES • • • • • • • •

Pyogenic abscess Portal venous gas with bowel infarction Focal confluent fibrosis Cholangiocarcinoma (peripheral) Regenerative and dysplastic nodules Cirrhosis Hepatic angiomyolipoma Other causes of transient hepatic attenuation (THADs) and intensity (THIDs) differences • Congenital absence of hepatic segments

Postoperative Changes, Liver

Definitions • Iatrogenic changes to hepatic morphology that may cause or simulate pathologic conditions

IMAGING Imaging Recommendations • Best imaging tool ○ Imaging test that shows morphology and hemodynamic characteristics of hepatic lesion • Protocol advice ○ Correlate with medical records and history of prior intervention

CT Findings • Gas collection in hepatic or perihepatic lesion ○ Abscess is primary concern, but also consider iatrogenic causes ○ Iatrogenic infarction of hepatic mass or liver parenchyma – Sudden death of hepatic (or other) tissue releases gas, ± coexisting infection □ Examples: Radiofrequency ablation, hepatic arterial chemoembolization, hepatic arterial occlusion (intentional or not) – Gas released from sudden death of tissue □ Does not imply infection of tissue □ Clinical syndrome (fever, pain, leukocytosis) may mimic sepsis ○ Retained absorbable oxidized cellulose (Surgicel) – May be placed intraoperatively and left in place to control bleeding – Appears as spherical, sponge-like collection of gas bubbles with little or no fluid component □ Tightly packed gas bubbles ± linear arrangement; no enhancing wall □ Fixed location and appearance on sequential exams □ Highly echogenic mass on US with posterior reverberation artifact • Iatrogenic causes of portal venous gas ○ Any procedure resulting in sudden death of hepatic parenchyma may release hepatic parenchymal ± portal venous gas – Examples: Surgical ligation or transcatheter occlusion of hepatic artery (deliberate or unintentional) – Might be used to devascularize hypervascular liver mass, benign (e.g., focal nodular hyperplasia or adenoma) or malignant • Focal hepatic malignancy following chemoembolization ○ May be accompanied by embolized, iodinated, poppyseed oil (Ethiodol, Lipiodol) ○ very high (metallic) density within treated lesion on CT – May mimic calcified mass on plain radiography or NECT – May mimic hypervascular tumor on arterial phase CECT ○ MR will show low-intensity signal within lesion on T2WI – As opposed to typical appearance of viable tumor (high signal on T2WI)

○ Lesions treated with intraarterial chemotherapy or radioactive microspheres (without Ethiodol) – Effectively treated lesions are hypovascular and nonenhancing on CECT and MR – Usual appearance on MR: Hyperintense on T1WI, hypointense on T2WI (opposite of usual appearance of viable tumor) • Consider response to systemic chemotherapy ○ Treated tumor often undergoes progressive volume loss and fibrosis – Appearance may simulate other hepatic lesions with fibrous stroma □ e.g., focal confluent fibrosis or peripheral cholangiocarcinoma ○ Appearance may resemble cirrhosis (pseudocirrhosis) – Volume loss, surface nodularity, multifocal capsular retraction, ± signs of portal hypertension – Diffuse hepatic metastases from breast cancer are especially prone to pseudocirrhosis – Even untreated metastases can sometimes elicit fibrotic response mimicking cirrhosis • Consider prior resection of portions of liver ○ May have similar appearance to congenital absence or hypoplasia of hepatic segments – May also resemble atrophy of anterior and medial segments that occurs with cirrhosis ○ Resected focus may be packed with omental fat to control leakage of blood or bile – Appearance may simulate fat-containing hepatic mass (e.g., angiomyolipoma or hepatocellular carcinoma) • Iatrogenic arterioportal (AP) fistula ○ Common but usually self-limited complication of percutaneous liver biopsy ○ Enlarged hepatic arterial branch with early opacification of accompanying portal venous branch and hyperenhancement of subtended segment of liver on arterial phase CECT (or MR) ○ May resemble other causes of AP fistulas (e.g., hereditary hemorrhagic telangiectasia [HHT] or transient hepatic attenuation differences [THADs]) – HHT has enlarged hepatic artery, innumerable telangiectasias, and vascular masses in liver with heterogeneous parenchymal enhancement – Other THAD etiologies usually have occlusion of portal venous branch (e.g., by malignant tumor) or sump effect of hypervascular mass in liver ○ Small peripheral AP shunts are common, spontaneous findings in cirrhotic liver

Liver

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Pyogenic Abscess • Usual appearance is multiloculated collection of fluid ± gas in right lobe of liver • Almost always contains more fluid than seen with bioabsorbable gelatin sponge

Portal Venous Gas With Bowel Infarction • Should see gas in bowel wall (pneumatosis) in addition to portal venous gas • Clinical setting for iatrogenic portal venous gas is usually different than for bowel infarction 745

Liver

Postoperative Changes, Liver

Focal Confluent Fibrosis • Wedge-shaped focus of hepatic volume loss and fibrosis occurs in advanced cirrhosis ○ Hepatic capsular retraction is usually more striking than with treated malignancy • Usually affects anterior and medial segments • No history of prior treatment for hepatic malignancy

Cholangiocarcinoma (Peripheral) • Appearance may be identical to focal confluent fibrosis or treated hepatic malignancy • Look for dilation of bile ducts within affected segment of liver • Delayed persistent enhancement is more common with cholangiocarcinoma than with treated hepatocellular carcinoma or metastases

Regenerative and Dysplastic Nodules • Typically hyperintense on T1WI and hypointense on T2WI • Similar to appearance of successfully treated primary or metastatic hepatic malignancies • History of prior treatment of tumor is key to diagnosis

Congenital Absence of Hepatic Segments • Usually affects anterior and medial segments • May be absent or, more commonly, atrophic • Appearance may resemble cirrhosis or result from surgical resection of hepatic segments • Absence of signs of cirrhosis or prior history are key to recognition

Cirrhosis • Nodular contour, volume loss (usually right anterior and medial segments more than caudate), and widened fissures • May show signs of portal hypertension (ascites, varices, splenomegaly) • Etiology is usually known (alcohol, chronic viral hepatitis, etc.) • No history of prior treated malignancy

Consider • Knowing history is key to appropriate diagnosis

SELECTED REFERENCES 1. 2.

3. 4.

5. 6. 7. 8.

9. 10.

11.

12.

13.

14. 15.

16.

Hepatic Angiomyolipoma

17.

• Soft tissue ± fat-density mass in liver • May occur with angiomyolipomas in kidney, especially in tuberous sclerosis complex • Iatrogenic placement of fat in surgical defect in liver may show surgical clip ± volume loss, unlike hepatic angiomyolipoma

18.

Other Causes of Transient Hepatic Attenuation and Intensity Differences (THADs and THIDs)

21.

• Most common causes are small, peripheral, AP shunts in cirrhotic patients or occlusion of portal vein branches by tumor or clot • Iatrogenic arteriovenous fistulas have early opacification of portal vein branch, not occlusion

CLINICAL ISSUES Demographics • Age ○ More common in elderly; can affect children

746

DIAGNOSTIC CHECKLIST

19. 20.

Rajković Z et al: Differential diagnosis and clinical relevance of pneumobilia or portal vein gas on abdominal x-ray. Acta Clin Croat. 52(3):369-73, 2013 Kim JH et al: Percutaneous radiofrequency ablation using internally cooled wet electrodes for the treatment of hepatocellular carcinoma. AJR Am J Roentgenol. 198(2):471-6, 2012 Pai M et al: Radiofrequency assisted liver resection: analysis of 604 consecutive cases. Eur J Surg Oncol. 38(3):274-80, 2012 Park SY et al: Radiofrequency ablation of hepatic metastases after curative resection of extrahepatic cholangiocarcinoma. AJR Am J Roentgenol. 2011 Dec;197(6):W1129-34. Erratum in: AJR Am J Roentgenol. 198(1):2, 2012 Kim AY et al: Venous thrombosis after radiofrequency ablation for hepatocellular carcinoma. AJR Am J Roentgenol. 197(6):1474-80, 2011 Shah PA et al: Hepatic gas: widening spectrum of causes detected at CT and US in the interventional era. Radiographics. 31(5):1403-13, 2011 Arnold AC et al: Postoperative Surgicel mimicking abscesses following cholecystectomy and liver biopsy. Emerg Radiol. 15(3):183-5, 2008 Khankan AA et al: Hepatocellular carcinoma treated with radio frequency ablation: an early evaluation with magnetic resonance imaging. J Magn Reson Imaging. 27(3):546-51, 2008 Simon CJ et al: Pulmonary radiofrequency ablation: long-term safety and efficacy in 153 patients. Radiology. 243(1):268-75, 2007 Zhang YJ et al: Hepatocellular carcinoma treated with radiofrequency ablation with or without ethanol injection: a prospective randomized trial. Radiology. 244(2):599-607, 2007 Ahrar K et al: Percutaneous radiofrequency ablation of renal tumors: technique, complications, and outcomes. J Vasc Interv Radiol. 16(5):679-88, 2005 Lencioni R et al: Early-stage hepatocellular carcinoma in patients with cirrhosis: long-term results of percutaneous image-guided radiofrequency ablation. Radiology. 234(3):961-7, 2005 Lu DS et al: Radiofrequency ablation of hepatocellular carcinoma: treatment success as defined by histologic examination of the explanted liver. Radiology. 234(3):954-60, 2005 Oei T et al: Radiofrequency ablation of liver tumors: a new cause of benign portal venous gas. Radiology. 237(2):709-17, 2005 Sandrasegaran K et al: Distinguishing gelatin bioabsorbable sponge and postoperative abdominal abscess on CT. AJR Am J Roentgenol. 184(2):47580, 2005 Wah TM et al: Image-guided percutaneous radiofrequency ablation and incidence of post-radiofrequency ablation syndrome: prospective survey. Radiology. 237(3):1097-102, 2005 Iannitti DA et al: Portal venous gas detected by computed tomography: is surgery imperative? Dig Surg. 20(4):306-15, 2003 Rossi S et al: Percutaneous radio-frequency thermal ablation of nonresectable hepatocellular carcinoma after occlusion of tumor blood supply. Radiology. 217(1):119-26, 2000 Oto A et al: MR characteristics of oxidized cellulose (Surgicel). AJR Am J Roentgenol. 172(6):1481-4, 1999 Melamed JW et al: Sonographic appearance of oxidized cellulose (Surgicel): pitfall in the diagnosis of postoperative abscess. J Ultrasound Med. 14(1):2730, 1995 Young ST et al: Appearance of oxidized cellulose (Surgicel) on postoperative CT scans: similarity to postoperative abscess. AJR Am J Roentgenol. 160(2):275-7, 1993

Postoperative Changes, Liver Liver

(Left) Axial T1WI MR of a hepatocellular carcinoma (HCC) following arterial chemoembolization shows the mass as hyperintense, which would be unusual for a viable HCC. (Right) In the same patient, the nonviable HCC lesion is hypointense on T2WI, which would be atypical for a viable HCC.

(Left) Arterial phase CECT of hepatocellular carcinoma shows a subtle, hypervascular, 2 cm nodule in the right lobe, along with signs of cirrhosis (widened fissures, etc.). (Right) Portal venous phase image in the same patient shows classic washout of contrast medium from the nodule , essentially diagnostic of hepatocellular carcinoma in this setting. The patient was treated with transarterial chemoembolization, including Lipiodol.

(Left) Follow-up NECT in the same patient shows retention of the iodinated Lipiodol within the tumor. Note the indirect evidence of hepatic injury, with volume loss of the right lobe and ascites. (Right) Arterial phase CECT shows hyperenhancement of a portion of the lateral segment of the liver (THAD) and early enhancement of the portal vein branch that drains this segment. This represents an arterioportal shunt and is probably the result of the prior biopsy of the liver at this site.

747

Liver

Transjugular Intrahepatic Portosystemic Shunt (TIPS) KEY FACTS

TERMINOLOGY

PATHOLOGY

• Shunt between main portal vein and hepatic vein created with balloon-expandable metallic stent

• Stenosis is usually secondary to intimal fibroplasia within hepatic vein or TIPS itself • Associated abnormalities ○ Hepatic encephalopathy as portal flow bypasses liver

IMAGING • Goal of US: Detect stenosis before shunt occludes or symptoms recur • Best imaging tool ○ Controversial whether CTA/MRA is superior to US for TIPS surveillance ○ US is primary TIPS surveillance tool ○ CTA or MRA indicated if US is technically compromised or equivocal

TOP DIFFERENTIAL DIAGNOSES • Portal vein occlusion • Hepatic vein occlusion • Inferior vena cava occlusion

(Left) Graphic of TIPS shunt creation shows the hepatic vein punctured within 2 cm of the IVC. The metallic wire TIPS extends to the right portal vein, adjacent to its junction with the main portal vein. (Right) Image from a TIPS procedure shows the IV catheter proceeding down the IVC, then penetrating the liver parenchyma to enter the portal vein . The intraparenchymal tract is dilated with a balloon . Incidentally noted is a plastic biliary stent .

(Left) Film from the same procedure shows the TIPS itself deployed with its distal end in the hepatic vein and its proximal end in the main portal vein . (Right) Longitudinal color Doppler ultrasound shows the mid portion of a normally patent TIPS . Although the stent is highly echogenic, it does not obstruct sonographic visualization. Color Doppler indicates brisk flow toward the heart, the expected finding.

748

CLINICAL ISSUES • Maintaining TIPS patency is the major problem

DIAGNOSTIC CHECKLIST • Consider TIPS malfunction if shunt velocity is < 90 cm/s or portal vein velocity is < 35 cm/s • Image interpretation pearls ○ Low flow is difficult to detect with US ○ Confirm occlusion angiographically (CTA, MRA, DSA)

Transjugular Intrahepatic Portosystemic Shunt (TIPS)

Abbreviations

– Absence of flow: Occlusion □ Check with spectral Doppler (more sensitive); always confirm angiographically

• Transjugular intrahepatic portocaval shunt (TIPS)

Other Modality Findings

Definitions

• CTA, MRA ○ Anatomic depiction of stenosis, occlusion, or collateralization ○ IV contrast administration is essential for CTA; generally required for MRA

• Shunt between main portal vein (PV) and hepatic vein (HV) created with balloon-expandable metallic stent

IMAGING General Features

Imaging Recommendations

• Location ○ Most common route: Right HV right PV main PV • Size ○ 10-12 mm in diameter • Morphology ○ Typically follows curved course through hepatic parenchyma ○ Portal end slightly proximal to main PV bifurcation ○ Hepatic end located at, or slightly cephalad to, junction of HV and inferior vena cava (IVC)

• Best imaging tool ○ Controversial whether CTA or MRA is superior to US for TIPS surveillance ○ US is primary TIPS surveillance tool ○ CTA/MRA – Indicated if US is technically compromised or equivocal – Offers global view □ May be important in cases of suspected tumor occlusion of TIPS • Protocol advice ○ Pre-TIPS assessment (grayscale, color Doppler, spectral Doppler), for – Liver morphology – Hepatic masses (very important) – Presence and volume of ascites and pleural fluid – Location, patency, and flow direction in PVs and splenic veins (SVs) □ PV bifurcation may lie outside of liver □ Puncture at this point may cause fatal exsanguination – Measure PV flow velocity – Patency and flow direction in right and left PV branches – Patency and flow direction in 3 major HV trunks – IVC patency ○ Post-TIPS assessment (grayscale, color Doppler, spectral Doppler) – Hepatic masses – Presence and volume of ascites and pleural fluid – Stent configuration/position – Patency and flow direction in PV and its branches – Measure velocity mid-PV (not adjacent to shunt) – Assess shunt with color Doppler – Doppler waveforms/peak velocities: Proximal, mid, distal shunt – Compare findings with prior results before discharging patient (recheck if needed) – Presence of stenosis □ If present, peak stenosis velocity/post-stenotic turbulence – Patency, flow direction, Doppler waveforms in HV

Ultrasonographic Findings • Grayscale ultrasound ○ Echogenic stent easily seen on grayscale images but does not block sound transmission – Fabric-covered stent may cause acoustic shadowing soon after placement □ Probably due to gas bubbles trapped in fabric □ May preclude US evaluation of TIPS patency for a few days □ Usually resolves, allowing subsequent US surveillance for TIPS stenosis ○ Stent is typically curved but not kinked ○ Hepatic and portal ends "squarely" within veins (best seen on grayscale US) • Pulsed Doppler ○ Portal vein, satisfactory function – Hepatopetal flow toward heart – Flow toward shunt in right and left portal branches (occasionally away in left branch) ○ Shunt malfunction – Hepatofugal or bidirectional flow within TIPS – Peak velocity in portal vein < 35 cm/s – Flow away from shunt (hepatopetal) in right and left portal branches ○ Within shunt, malfunction – Continuous flow (no pulsatility or respiratory change) – Shunt velocity < 90 or > 250 cm/s at any point – Temporal drop in velocity 50 cm/s – Point-to-point increase in velocity 50 cm/s indicates focal stenosis – Focal severe turbulence (post stenosis) – Absence of flow: Occlusion □ Always confirm angiographically • Color Doppler ○ Within shunt, malfunction – Visible stenosis, focal or diffuse – Focal color change indicates high velocity – Focal severe flow disturbance (post stenosis)

Liver

TERMINOLOGY

Angiographic Findings • Portal venography via jugular vein catheterization ○ Definitive test for TIPS stenosis or occlusion ○ May allow balloon dilation of TIPS lumen or placement of new shunt within stenotic TIPS

749

Liver

Transjugular Intrahepatic Portosystemic Shunt (TIPS)

DIFFERENTIAL DIAGNOSIS Portal Vein Occlusion • May occur in patients ± TIPS ○ Hypercoagulable states, pancreatitis, tumor invasion, dehydration, trauma, cirrhosis

Hepatic Vein Occlusion • May occur ± TIPS ○ e.g., Budd-Chiari syndrome, tumor invasion (especially by hepatocellular carcinoma [HCC])

IVC Occlusion • Rarely caused by TIPS • May occur in primary (IVC sarcoma) or invasion by adjacent tumor (e.g., HCC, renal cell carcinoma)

PATHOLOGY General Features • Etiology ○ Stenosis usually secondary to intimal fibroplasia within TIPS

○ Hepatic arterial injury and arteriovenous fistula ○ Gallbladder injury • Guarded prognosis ○ Maintaining shunt patency is difficult ○ Inevitable liver disease progression ○ High risk of cirrhosis-related HCC ○ 7-45% 30-day mortality

DIAGNOSTIC CHECKLIST Consider • TIPS malfunction if flow velocity within TIPS is < 90 or > 250 cm/s, or PV velocity < 35 cm/s

Image Interpretation Pearls • Low flow difficult to detect with US; confirm occlusion angiographically (CTA, MRA, DSA)

SELECTED REFERENCES 1.

2.

Staging, Grading, & Classification • Occlusion, low- or high-grade stenosis

Gross Pathologic & Surgical Features • Chronic occlusion or stenosis secondary to build-up of intimal fibroplasia

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Signs of failing TIPS – Recurrence of ascites, variceal hemorrhage • Clinical profile ○ Candidates for TIPS – Cirrhosis with intractable ascites or variceal bleeding – Budd-Chiari syndrome – Temporizing measure, pre liver transplantation

Demographics • Age ○ Generally adults, may be used in children • Epidemiology ○ Maintaining TIPS shunt patency is the major problem – Primary patency (no intervention): 1 year = 25-66%; 2 year = 5-42% – Secondary (intervention-assisted) patency: 1 year = 85%; 2 year = 61%; 5 year = 55%

Natural History & Prognosis • Causes of TIPS shunts failure ○ Technical problems: Malposition, kinks, incomplete deployment, hepatic perforation with hemoperitoneum, or bile leak ○ Venous trauma during stent insertion: HV stenosis often precedes PV fibrosis or stenosis ○ Neointimal hyperplasia (may be ameliorated by covered stents but insufficient data) ○ Thrombosis 750

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Orloff MJ: Fifty-three years' experience with randomized clinical trials of emergency portacaval shunt for bleeding esophageal varices in Cirrhosis: 1958-2011. JAMA Surg. 149(2):155-69, 2014 Kirby JM et al: Image-guided intervention in management of complications of portal hypertension: more than TIPS for success. Radiographics. 33(5):1473-96, 2013 Qin JP et al: Clinical effects and complications of TIPS for portal hypertension due to cirrhosis: a single center. World J Gastroenterol. 19(44):8085-92, 2013 Micol C et al: Contrast-enhanced ultrasound: a new method for TIPS followup. Abdom Imaging. 37(2):252-60, 2012 Wu X et al: Favorable clinical outcome using a covered stent following transjugular intrahepatic portosystemic shunt in patients with portal hypertension. J Hepatobiliary Pancreat Sci. 17(5):701-8, 2010 Kim MJ et al: Technical essentials of hepatic Doppler sonography. Curr Probl Diagn Radiol. 38(2):53-60, 2009 Bureau C et al: Patency of stents covered with polytetrafluoroethylene in patients treated by transjugular intrahepatic portosystemic shunts: longterm results of a randomized multicentre study. Liver Int. 27(6):742-7, 2007 Maleux G et al: Dynamic MR perfusion measurements before and after TIPS in cirrhotic patients with refractory ascites. Acad Radiol. 14(11):1400-8, 2007 Bauer J et al: The role of TIPS for portal vein patency in liver transplant patients with portal vein thrombosis. Liver Transpl. 12(10):1544-51, 2006 Carr CE et al: Role of ultrasound surveillance of transjugular intrahepatic portosystemic shunts in the covered stent era. J Vasc Interv Radiol. 17(8):1297-305, 2006 Harrod-Kim P et al: Predictors of early mortality after transjugular intrahepatic portosystemic shunt creation for the treatment of refractory ascites. J Vasc Interv Radiol. 17(10):1605-10, 2006 Barrio J et al: Comparison of transjugular intrahepatic portosystemic shunt dysfunction in PTFE-covered stent-grafts versus bare stents. Eur J Radiol. 55(1):120-4, 2005 Benito A et al: Doppler ultrasound for TIPS: does it work? Abdom Imaging. 29(1):45-52, 2004 Middleton WD et al: Doppler evaluation of transjugular intrahepatic portosystemic shunts. Ultrasound Q. 19(2):56-70; quiz 108 - 10, 2003 Bodner G et al: Color and pulsed Doppler ultrasound findings in normally functioning transjugular intrahepatic portosystemic shunts. Eur J Ultrasound. 12(2):131-6, 2000 Ong JP et al: Transjugular intrahepatic portosystemic shunts (TIPS): a decade later. J Clin Gastroenterol. 30(1):14-28, 2000

Transjugular Intrahepatic Portosystemic Shunt (TIPS) Liver

(Left) Grayscale US in a 51year-old man who underwent a TIPS 5 months ago, now with a recent increase in ascites, demonstrates highly reflective echoes typical of the TIPS shunt walls . (Right) Longitudinal color Doppler ultrasound in the same patient, scanned through the mid-shunt level, demonstrates low-velocity flow (45 cm/s) within the shunt . A subsequent angiogram revealed a high-grade TIPS stenosis involving the hepatic venous side of the shunt.

(Left) Color Doppler US in a 47-year-old woman who underwent TIPS 7 months ago illustrates marked aliasing and turbulent flow within the distal shunt . (Right) Longitudinal spectral Doppler ultrasound in the same patient demonstrates markedly increased velocity of flow in the distal shunt (255 cm/s) , findings consistent with midshunt stenosis.

(Left) Portal venography in a 66-year-old man with a suspected TIPS stenosis based on Doppler ultrasound reveals multiple areas of luminal narrowing within the parenchymal portion of the shunt, usually due to intimal hyperplasia. (Right) Portal venography in a 41-year-old man presenting with a suspected TIPS malfunction, based on a recurrence of ascites, demonstrates stenosis at the hepatic vein at the proximal end of the TIPS.

751

Liver

Transjugular Intrahepatic Portosystemic Shunt (TIPS)

(Left) Longitudinal pulsed Doppler ultrasound shows markedly elevated flow velocity (314 cm/s) at the narrowed lumen of the TIPS, clearly indicating stent stenosis. (Right) Longitudinal color Doppler US in the same case shows focal narrowing and high velocity (blue shades) near the hepatic end of the TIPS.

(Left) This initial US was performed 1 day after placement of a fabric-lined or "covered" stent . Note the acoustic shadow deep to the stent , precluding optimal US evaluation for stent patency. (Right) Repeat US several months later shows resolution of the acoustic shadow deep to the TIPS. Color Doppler US shows narrowing of the lumen and turbulent flow, likely due to intimal fibroplasia.

(Left) Color Doppler US in a 64-year-old man with cirrhosis and a recurrent upper GI bleed 1 month after TIPS placement shows a TIPS shunt with complete absence of flow, indicating TIPS occlusion. (Right) Image from a portal venogram in the same patient shows opacification of the portal branches , but no opacification of the TIPS , confirming shunt occlusion.

752

Transjugular Intrahepatic Portosystemic Shunt (TIPS) Liver

(Left) A 55-year-old man had a TIPS placed 3 years previously and returned with increased ascites and liver failure. Color Doppler US shows no flow within the TIPS , the proximal end of which terminates in a markedly distended main portal vein . (Right) US in the same patient shows marked dilation of the left portal vein, which seemed to be filled with vascularized tumor . The liver was very heterogeneous, but no discrete mass was identified.

(Left) Arterial phase CECT performed the next day showed occlusion of the TIPS lumen, with the proximal (portal) end of the TIPS lying within a massively dilated portal vein that was distended with contrastenhancing tumor thrombus . (Right) Portal venous phase CECT in the same case shows the occluded TIPS and contrast washout from the portal vein tumor thrombus along with the primary HCC that fills the left lobe of the liver .

(Left) CT section in the same case shows the TIPS entering the portal vein, along with the primary HCC and its extension into the left portal vein . (Right) CT section in the same case shows the proximal end of the TIPS embedded within a tumor thrombus that distends the main portal vein.

753

Liver

Hepatic Transplantation KEY FACTS

TERMINOLOGY • Orthotopic liver transplantation (OLT)

IMAGING • Allograft rejection ○ No reliable imaging findings to suggest or confirm diagnosis • Biliary leak ○ From entry of T tube: Easily treated ○ From biliary anastomosis: Requires revision ○ From intrahepatic ducts: Biliary necrosis; catastrophic • Biliary obstruction ○ Balloon dilation and stenting • Hepatic artery stenosis ○ Damped waveform in hepatic artery distal to stenosis: Slow systolic upstroke; decreased resistive index (< 0.5) ○ Narrowing at hepatic artery anastomosis with turbulent flow, focally velocity (> 0.3 m/s) ○ CT (or MR) angiography for detailed analysis

(Left) Graphic shows the typical anatomy for whole liver transplantation. Some liver is cut away to show anastomoses more clearly, as there are a number of common variations for vascular and biliary anastomoses. (Right) Graphic shows the typical anatomy of an adult partial-liver recipient (living donor). Note the biliaryenteric anastomosis to a Roux limb. Complications are more common than for whole liver allografts due to the many transected vessels and ducts and the small size of the structures for anastomosis.

(Left) Axial CECT shows a "halo" of low density surrounding some of the portal veins. This is a typical feature of periportal lymphedema, which is common and of no clinical concern in the early posttransplantation setting. (Right) T-tube cholangiogram shows a mild waist-like narrowing at the biliary anastomosis without dilation of the upstream bile ducts. This is the normal appearance of a duct-to-duct anastomosis.

754

• Hepatic artery thrombosis ○ Accompanied by biliary necrosis; catastrophic • Hepatic arterial pseudoaneurysm ○ From biopsy or surgical error • Portal vein stenosis ○ Uncommon: Treated by angioplasty and stent • IVC anastomotic stenosis ○ Can be suggested by US (anastomotic narrowing, turbulent, rapid flow across anastomosis), CT, or MR • Recurrent disease within allograft ○ Primary sclerosing cholangitis: Tends to recur ○ Hepatocellular carcinoma ○ Recurrent viral hepatitis or primary biliary cirrhosis • Extrahepatic complications ○ Abdominal fluid collections ○ Post-transplant lymphoproliferative disorder

Hepatic Transplantation

Definitions • Whole liver allograft (cadaver donor) ○ Orthotopic liver transplantation (OLT) ○ Included from donor – Intact inferior vena cava (IVC) □ Anastomosed end-to-end or as "piggy-back" sideto-side – Hepatic artery (HA) □ Anastomosed end-to-end, sometimes with aortic (Carrel) patch – Portal vein (PV) □ End-to-end anastomosis – Bile duct □ Anastomosed end-to-end with recipient duct (70%) or to Roux limb • Cadaver split liver (2 halves to separate recipients) ○ Right lobe to adult recipient (IVC, HA, PV, bile duct) ○ Left lobe to child recipient (complex anastomoses) • Living donor transplant ○ Child recipient: Generally receives lateral segment of donor liver ○ Adult recipient: Receives right lobe of donor ○ Complex biliary and vascular anastomoses

IMAGING Normal Post-Transplantation Findings • Right pleural effusion (usually resolves spontaneously) • Right adrenal hematoma ○ Adrenal veins injured or ligated during OLT ○ No clinical importance • Periportal lymphedema ○ Lucent "halo" around PVs and IVC ○ No significance; resolves spontaneously • Vascular and biliary anastomoses may show waist-like narrowing ○ Should not have functional narrowing ○ Normal indices on US: Hepatic artery – Resistive index (RI): 0.5-0.7 – Rapid systolic acceleration time (< 80 ms) – Flow velocity at anastomosis < 200-300 cm/s ○ Portal vein – Mild phasicity with respiration; no turbulent flow ○ Hepatic veins (HV), IVC – Triphasic waveforms reflective of cardiac contractility • Biliary anastomosis ○ Waist-like narrowing without dilation of upstream ducts ○ Duct-duct anastomosis may be stented with T tube for several months – Allows access for cholangiography • Liver parenchyma ○ Normal texture by all imaging modalities ○ Partial liver recipients – Liver grows to near normal volume within months

Pre-Transplantation Evaluation • Imaging and clinical evaluation of severity of cirrhosis and portal hypertension

○ Size and morphology of liver ○ Ascites, splenomegaly, extent of varices ○ Presence and stage of hepatocellular carcinoma (HCC) – Size, number, presence of vascular invasion, extrahepatic spread – Early stage HCC may be good candidate for transplantation (receives increased MELD points) ○ Model for end-stage liver disease (MELD) – Based on etiology of cirrhosis, plus serum creatinine, bilirubin, and International Normalised Ratio (INR) • Detailed evaluation of hepatic vessels ○ Note any anomalies (e.g., "replaced" HA) – Check for severe atherosclerosis, median arcuate ligament compression of celiac axis ○ PV: Check for thrombosis, mural calcification, diminutive size ○ HVs: Check for thrombosis (Budd-Chiari)

Liver

TERMINOLOGY

Allograft Rejection • No reliable imaging findings to suggest or confirm diagnosis • Clinical suspicion leads to US-guided biopsy of allograft

Biliary Complications • Biliary leak ○ Leak from entry of T tube – Often encountered after removal of T tube after several months – Recognized by cholangiography, biliary scintigraphy, or aspiration of fluid collection identified by US or CT – Easily confirmed by ERCP and treated by placement of temporary biliary stent ○ Leak from biliary anastomosis – Usually due to surgical error – Often requires surgical revision of anastomosis ○ Leak from intrahepatic ducts – May be due to biopsy (resolves spontaneously) – Usually due to biliary necrosis □ Result of HA stenosis or thrombosis – Usually requires retransplantation in adults ○ Strictures or irregularity of intrahepatic ducts – Nonspecific – Possible etiologies include incomplete distention (artifact), infection, rejection, ischemia, recurrent primary sclerosing cholangitis • Biliary filling defects ○ Stones: Usually late complication ○ Debris: Cholangitis, infection, rejection, ischemia ○ May respond to endoscopic sweeping of debris from duct ± temporary stent • Biliary obstruction ○ Anastomotic – Complete: Requires surgical intervention ○ Partial – Usually responds to balloon dilation and stenting

Vascular Complications • HA stenosis ○ Clinical signs: Worsening liver function ○ US: Usually 1st imaging study to suggest diagnosis 755

Liver

Hepatic Transplantation

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– Examine artery in porta hepatis and within liver (main, right, and left HA) – Damped (tardus parvus) waveform in HA distal to stenosis □ Slow systolic upstroke; decreased RI (< 0.5) – Narrowing at HA anastomosis with turbulent flow, focally velocity (> 0.3 m/s) ○ CT (or MR) angiography can confirm stenosis, occlusion, redundancy, kinking, or other abnormalities of HA ○ Catheter angiography usually reserved for intervention (balloon angioplasty ± stent) HA thrombosis ○ Usually marked by liver dysfunction, fever, malaise ○ Imaging shows no flow within HA beyond anastomosis ○ Often accompanied by biliary necrosis (bile ducts totally dependent on arterial supply) – Focal hypodense lesion or fluid collection within liver □ May have branching pattern along porta triads – Can be confirmed by needle aspiration and percutaneous drainage of biloma – Adults: Usually fatal or requires retransplantation – Children: May develop sufficient collateral HA flow to preserve allograft function Hepatic arterial pseudoaneurysm ○ Intrahepatic: Usually due to liver biopsy – May resolve spontaneously or require embolic therapy ○ At HA anastomosis – May be due to technical error or infection – May respond to stent across aneurysm site or require surgical revision PV stenosis ○ Relatively uncommon ○ Can be suggested by US (turbulent, rapid flow across anastomosis; loss of respiratory phasicity), CT, or MR ○ Confirmed by transhepatic portography – Can be treated by angioplasty and stent IVC anastomotic stenosis ○ Relatively uncommon ○ Can be suggested by US, CT or MR (anastomotic narrowing, turbulent, flow across anastomosis) – US: Loss of respiratory and cardiac phasicity (should be triphasic) – May see echogenic clot within IVC caudal to anastomosis ○ Presence of intraluminal pressure gradient across anastomosis confirms physiologically significant stenosis – Can be treated by angioplasty and stent

○ Hepatitis B rarely recurs after transplantation due to effective antiviral prophylaxis ○ Hepatitis C recurs more frequently, as prophylaxis is less effective

Extrahepatic Complications • Abdominal fluid collections ○ Loculated ascites ± infection; abscess; biloma ○ Easily identified by CT ○ Usually amenable to image-guided aspiration and drainage • Post-transplant lymphoproliferative disorder (PTLD) ○ Caused by Epstein-Barr viral infection and immunosuppression ○ Clinical spectrum – Polyclonal proliferation of lymphocytes □ Treated with antiviral medication – High-grade monoclonal lymphoma (non-Hodgkin) ○ Soft tissue density masses in lymph nodes, bowel, hepatic allograft, other organs and structures throughout body – Recurrence within hepatic allograft □ Soft tissue density mass(es) with tendency toward periportal distribution

CLINICAL ISSUES Natural History & Prognosis • Prognosis is good for properly selected patients • Depends largely on patient's overall health at OLT ○ Varies somewhat by etiology of liver disease – e.g., better for patients with alcoholic cirrhosis than patients with chronic viral hepatitis ○ 1 year patient survival = 80-90%; 5 year = 75-88%

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • US is a good surveillance tool for most causes of allograft dysfunction

SELECTED REFERENCES 1. 2. 3.

Recurrent Disease Within Allograft

4.

• Primary sclerosing cholangitis ○ Tends to recur several years after OLT • HCC ○ Relatively uncommon with proper selection of OLT candidates with early-stage HCC (according to Milan or UCSF criteria) ○ Appearance is similar to HCC in native liver – Heterogeneous hypervascular mass with washout; tendency toward venous invasion • Recurrent viral hepatitis or primary biliary cirrhosis ○ Detected by imaging with return of cirrhotic morphology – Widened fissures, ascites, varices

5.

Lai Q et al: Hepatocellular cancer: how to expand safely inclusion criteria for liver transplantation. Curr Opin Organ Transplant. 19(3):229-34, 2014 Song GW et al: Living donor liver transplantation. Curr Opin Organ Transplant. 19(3):217-22, 2014 Liu YI et al: Multidetector computed tomography triphasic evaluation of the liver before transplantation: importance of equilibrium phase washout and morphology for characterizing hypervascular lesions. J Comput Assist Tomogr. 36(2):213-9, 2012 Singh AK et al: Imaging of preoperative liver transplantation in adults: what radiologists should know. Radiographics. 31(4):1017-30, 2011 Chen HL et al: Diagnosis and interventional radiological treatment of vascular and biliary complications after liver transplantation in children with biliary atresia. Transplant Proc. 40(8):2534-6, 2008

Hepatic Transplantation Liver

(Left) Axial CECT of a 57-yearold man with pain following recent transplantation shows a "halo" of low density surrounding the portal veins. (Right) CT section shows more of the periportal edema while the space around the hepatic veins is less affected. This is a common finding in the early posttransplantation setting and results from the transection of lymphatics and accumulation of lymph along the portal tracts. It generally resolves as lymphatic connections reform.

(Left) ERCP in a 55-year-old man shows narrowing at the biliary anastomosis and a filling defect within the duct , which may represent some debris. There is only mild dilation of the intrahepatic (donor) ducts. (Right) The same patient was treated with an endoscopic balloon sweep, dilation of the stricture, and placement of a temporary plastic stent with good results.

(Left) T-tube cholangiogram in a 45-year-old woman shows a collection of extraluminal contrast medium that originated from the site of entry of the T tube into the recipient bile duct just distal to the anastomosis . (Right) Axial CECT in the same patient reveals an extravasated collection of bile that was drained by USguided placement of a pigtail catheter. The patient recovered uneventfully, with removal of the T tube several months later.

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Liver

Hepatic Transplantation

(Left) Color Doppler ultrasound shows a classic damped tardus parvus wave pattern of the right hepatic artery, with a slowed systolic upstroke. Also note the decreased resistive index (RI) of 0.46 . These findings are usually indicative of hepatic artery stenosis. (Right) CT angiography in the same patient demonstrates marked tortuosity of the hepatic artery and at least 1 stenotic focus at the arterial anastomosis . Balloon angioplasty and stent were successful in relieving the stenosis.

(Left) Oblique pulsed Doppler ultrasound 1 day after transplant shows a normal hepatic artery Doppler waveform at the porta hepatis. RI is 0.59, which is normal. (Right) Color Doppler ultrasound in the same patient 1 day later shows a dampened flow within the hepatic artery with a tardus parvus waveform and a prolonged acceleration time (86 ms).

(Left) Oblique pulsed Doppler ultrasound in the same patient 2 days post transplant shows damped hepatic arterial Doppler waveforms due to hepatic arterial stenosis. Peak systolic velocity is 30 cm/s, and the RI has fallen to 0.41. (Right) CT angiography in the same case confirms a stricture at the hepatic artery anastomosis . Hepatic arterial anastomotic stenosis or thrombosis is a common cause of allograft dysfunction and may lead to biliary necrosis and failed transplantation.

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Hepatic Transplantation Liver

(Left) Axial CECT of a 61-yearold man with allograft dysfunction shows an opacified portal vein but no hepatic artery. (Right) Thick plane axial reconstruction in the same case shows occlusion of the hepatic artery near its anastomosis . This requires urgent revascularization by angioplasty or surgery, which is often unsuccessful. If this is the case, retransplantation is required.

(Left) Axial CECT shows a patent portal vein but no hepatic artery. There is a lowdensity lesion in the liver with a branching configuration that parallels the portobiliary tracts. This is a biloma resulting from hepatic artery thrombosis. (Right) A percutaneous catheter was introduced to decompress the biloma. Injection of the catheter opacifies nondilated ducts, but many of the duct walls are necrotic and are surrounded by an amorphous collection of bile and contrast medium.

(Left) CECT in a patient with deteriorating allograft function shows a large lowdensity lesion that has linear, branching, and rounded components, which represent the spectrum of findings from biliary ischemia in the allograft, due to hepatic artery thrombosis. Also note the ascites . (Right) This example of hepatic artery thrombosis shows ischemic bile duct injury with an eosinophilic bile cast . (Courtesy L. Yerian, MD.)

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Liver

Hepatic Transplantation

(Left) Color Doppler interrogation of the portal venous anastomosis shows turbulent rapid flow , suggesting stenosis. (Right) In the same patient, transhepatic cannulation of the portal vein and injection of contrast medium confirms a tight stenosis at the portal vein anastomosis . This was treated with balloon dilation with good results.

(Left) CECT of a 60-year-old man with lower extremity edema following transplantation shows a normal-caliber suprahepatic IVC . (Right) Axial CECT in the same case at the level of the anastomosis shows marked narrowing of the lumen. The IVC was distended on more caudal sections.

(Left) CT in the same case shows dilation of the IVC just caudal to the the anastomosis of the donor and recipient IVC. (Right) Inferior vena cavagram in the same patient confirms tight stenosis at the anastomosis . At least 1 collateral vein is opacified. Balloon dilation relieved the stricture with normalization of intraluminal pressure across the anastomosis.

760

Hepatic Transplantation Liver

(Left) In this patient who had hepatic dysfunction and leg swelling following a recent liver transplantation, a color Doppler sonogram suggests narrowing of the hepatic veins near their confluence . (Right) Axial CECT in the same case shows evidence of a "piggy-back" anastomosis of the donor IVC to the recipient IVC . The donor IVC and confluence of hepatic veins appear to be strictured .

(Left) More caudal section in the same case shows a narrowed donor IVC , a dilated recipient IVC , and periportal edema within the liver allograft. (Right) Coronal-reformatted CT image from the same study shows distention of the recipient IVC , stricture at the IVC anastomosis , and periportal edema . This patient had allograft dysfunction and leg edema.

(Left) CT reformation in the same case shows the strictured "piggy-back" anastomosis to the recipient IVC and narrowing of at least 1 of the hepatic veins . (Right) A catheter hepatic venogram confirms stenosis of the hepatic veins at the IVC anastomosis . These strictures were balloon-dilated with improvement of symptoms and liver function.

761

Liver

Hepatic Transplantation

(Left) Axial CECT in a 52-yearold man who had received a multivisceral transplant (liver, pancreas, and small bowel) shows the anastomotic site between the donor and recipient aorta with this vessel feeding the small bowel, liver, and pancreatic allografts, all of which appear normal. (Right) CT section in the same patient shows a normal appearance of the infrarenal aortic anastomosis and the pancreatic allograft .

(Left) Lower CT section in the same case shows a normal appearance of the small bowel allograft . All 3 transplanted organs functioned normally, and the patient no longer required parenteral nutrition nor insulin. (Right) Coronalreformatted CT in the same case shows the end-to-side aortic anastomosis , which supplied blood to all 3 allografts.

(Left) CT in a 54-year-old woman with a multivisceral transplant shows pancreatic and liver allografts. The small bowel allograft was normal in appearance on more caudal sections (not shown). The aortic anastomosis is noted on this axial CT. (Right) On this 3D reconstruction of the same CT scan, the donor aorta is redundant and acutely kinked , causing luminal narrowing and requiring surgical revision. The anastomosis with the native aorta is seen.

762

Hepatic Transplantation Liver

(Left) Axial CECT of a 55-yearold man with fever and weight loss months after transplantation due to posttransplant lymphoproliferative disorder (PTLD) shows hepatosplenomegaly with poorly defined hypodense masses within both organs. (Right) CT in the same patient also shows obstruction of intrahepatic bile ducts due to a combination of the hepatic tumor and porta hepatic adenopathy.

(Left) CT in the same patient shows more of the hepatic tumor (PTLD, ) and the obstructed bile ducts . (Right) CT in the same patient shows porta hepatic adenopathy that contributed to the biliary obstruction. This was partially relieved by a biliary stent . All of these features are typical of PTLD following hepatic transplantation.

(Left) Axial CECT in a patient with PTLD shows dilation of the intrahepatic bile ducts and a hypovascular mass in the hilum that compresses the portal vein and central bile ducts. Biopsy of the mass proved PTLD within the hepatic allograft. (Right) A more caudal section in the same patient shows the central hilar mass of PTLD that compresses and partially obstructs the portal vein and common hepatic duct.

763

Liver

Hepatic Cyst KEY FACTS

TERMINOLOGY • Simple hepatic cyst is benign, congenital, developmental lesion derived from biliary endothelium

IMAGING • Congenital or developmental ○ Simple hepatic or bile duct cyst • Often multiple: Usually < 10 ○ When > 10, consider autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas • Sharply defined margins, thin walls • Water density (-10 to +10 HU) • Usually no or few thin septations ○ No mural nodularity or wall calcification • Hemorrhage into cyst may simulate tumor ○ No enhancement of "solid" material ○ Varied MR signal intensity (due to mixed blood products) • US: Anechoic mass, accentuated through transmission ○ Smooth borders; thin or invisible wall

(Left) Axial CECT shows a spherical hepatic mass with water density and homogeneous contents. No internal debris or wall irregularities are present. This is a classic simple cyst. (Right) Ultrasound in the same patient shows an anechoic mass with accentuated through-transmission . Either CT or US would have been sufficient to establish the diagnosis in this patient.

(Left) Axial T1WI MR shows a large, cystic, hepatic mass that has homogeneous low intensity and several thin septa . (Right) Coronal T2WI shows uniform high intensity and septa . The cyst has remained stable for years, and no other evaluation or intervention was performed.

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• Size varies from few mm to > 20 cm ○ Rarely are the cysts of similar size ○ Helps to differentiate from biliary hamartomas, which are all usually < 15 mm

TOP DIFFERENTIAL DIAGNOSES • • • • • • • • •

AD polycystic disease, liver Cystic or necrotic metastases Biliary cystadenocarcinoma Biliary hamartomas Ciliated hepatic foregut cyst Hepatic cavernous hemangioma Biloma Hepatic pyogenic abscess Hydatid (echinococcal) disease

DIAGNOSTIC CHECKLIST • Sonography shows cyst morphology better than CT

Hepatic Cyst

Synonyms • Simple hepatic or bile duct cyst

Definitions • Benign, congenital, developmental lesion derived from biliary endothelium

– Higher signal intensity (due to mixed blood products) – may or may not show fluid level • T1 C+ ○ Uncomplicated or complicated cyst – No enhancement of contents • MRCP ○ Shows no communication with bile ducts

Liver

TERMINOLOGY

Ultrasonographic Findings

IMAGING General Features • Best diagnostic clue ○ Anechoic lesion with increased through-transmission and no mural nodularity on US • Location ○ Any location within liver • Size ○ Varies from few mm to > 20 cm – Rarely are the cysts of similar size – Helps to differentiate from biliary hamartomas, which are all usually < 15 mm • Morphology ○ Spherical or oval, well marginated • Key concepts ○ Classified based on etiology and pathogenesis ○ Congenital or developmental: Simple hepatic or bile duct cyst – Often multiple: Usually < 10 – No communication with bile ducts ○ When > 10 in number, fibropolycystic disease must be considered – i.e., autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas

• Grayscale ultrasound ○ Uncomplicated simple cyst – Anechoic mass; accentuated through transmission – Smooth borders; thin or invisible wall – No or few septations – No mural nodules or wall calcification ○ Hemorrhagic or infected hepatic cyst – Septations, internal debris – Thickened wall – ± calcification

Nonvascular Interventions • Cyst aspiration may be helpful in confirming infected or hemorrhagic cyst

Imaging Recommendations • Best imaging tool ○ Ultrasound, CT, or MR • Protocol advice ○ CT or MR should include unenhanced and contrastenhanced series ○ Obtain thin axial CT sections to minimize partial volume averaging and to facilitate multiplanar reformations

DIFFERENTIAL DIAGNOSIS

CT Findings

AD Polycystic Disease, Liver

• NECT ○ Simple liver or bile duct cyst – Sharply defined margins; thin walls – Water density (-10 to +10 HU) – Usually no septations (uncommonly 1 thin septa) – No fluid-debris levels – No mural nodularity or wall calcification ○ Hemorrhage into cyst may be indistinguishable from tumor – Mural nodularity, fluid-debris level – No enhancement of "solid" material • CECT ○ Simple cyst – Uncomplicated or complex □ No enhancement of cyst contents

• Hepatic cysts are multiple, of varying sizes, enlarge and distort liver • Often have contents of complex fluid due to prior hemorrhage • Cysts in other organs (50% have renal polycystic disease) ± family history of polycystic disease

MR Findings • Simple hepatic cyst ○ T1WI: Hypointense ○ Heavily T2WI – Markedly increased signal intensity due to pure fluid content – Sometimes indistinguishable from hemangioma • Complicated (hemorrhagic) cyst ○ T1WI and T2WI

Cystic or Necrotic Metastases • Most common with sarcoma metastases and gastrointestinal stromal tumor (GIST) ○ Especially likely to resemble cysts after chemotherapy • Enhancing mural nodules, thick septa • Complex contents, more evident on MR/US than CT

Biliary Cystadenocarcinoma • Usually large and solitary mass in older woman • Homogeneous, hypodense, water-density mass • Almost always has septations and mural nodularity ○ Rarely nonseptate; these are difficult to distinguish from cysts

Biliary Hamartomas • Multiple, usually all < 15 mm in diameter • Often have fibrous nodules in walls ○ Therefore, echogenic on US

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Liver

Hepatic Cyst

Ciliated Hepatic Foregut Cyst • Rare (< 100 cases) cystic mass with potential for development of squamous carcinoma in cyst wall • Appears as simple or multiloculated cyst • Cyst contents usually mucinous (> 90%) ○ Mucin may cause increased signal on T1WI

Demographics

• Simulates cyst on T2WI • Other sequences and imaging studies (US, CT, enhanced MR) ○ Easy distinction from cyst due to enhancement

• Age ○ Seen in any age group ○ Many increase slowly in size • Gender ○ M:F = 1:5 • Epidemiology ○ Prevalence: 5-15% of general population

Biloma

Natural History & Prognosis

• Usually results from trauma, including prior surgery • Biliary necrosis following liver transplantation often results in biloma • History and comparison with prior imaging usually makes distinction

• Complications: Infection, hemorrhage, rupture (all uncommon) • Large cyst: Symptoms due to compression ○ Of intrahepatic bile ducts: Jaundice ○ Of vessels: Varices or Budd-Chiari ○ Of gastric cardia: Dysphagia, abdominal pain

Hepatic Cavernous Hemangioma

Hepatic Pyogenic Abscess • Complex, septate, cystic mass • Heterogeneous contents, > water density • May show mural nodularity and thick enhancing wall

Hydatid (Echinococcal) Disease • Large, well-defined, cystic liver mass with numerous peripheral "daughter" cysts • ± calcification and dilated bile ducts

PATHOLOGY

Treatment • Large, symptomatic, infected hepatic cyst ○ Percutaneous aspiration and sclerotherapy with alcohol ○ Surgical resection or marsupialization (opening into peritoneal cavity)

DIAGNOSTIC CHECKLIST Consider • Rule out cyst-like hepatic lesions (infection, tumor)

General Features

Image Interpretation Pearls

• Etiology ○ Congenital simple hepatic cyst – Defective development of intrahepatic biliary duct • Associated abnormalities ○ Tuberous sclerosis

• Sonography shows cyst morphology better than CT ○ May show mural nodularity, debris, septa missed by CT

Gross Pathologic & Surgical Features • Simple hepatic cyst ○ Cyst wall: 1 mm thick

Microscopic Features • True simple hepatic cyst ○ Single unilocular cyst with serous fluid ○ Lined by cuboidal bile duct epithelium – Thin underlying rim of fibrous stroma ○ No communication with bile ducts

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Uncomplicated simple cysts are usually asymptomatic ○ Complicated cyst – Pain and fever (intracystic hemorrhage or infection) ○ Large cysts present with symptoms of mass effect – Abdominal pain, jaundice, palpable mass • Other signs/symptoms ○ Cyst rupture with right upper quadrant (RUQ) pain ○ Compression of stomach or duodenum nausea, early satiety 766

• Lab data is normal unless bile ducts are compressed • Diagnosis ○ Fine-needle aspiration and cytology (rarely necessary)

SELECTED REFERENCES 1.

Long J et al: Acute Budd-Chiari syndrome due to a simple liver cyst. Ann R Coll Surg Engl. 96(1):109E-111E, 2014 2. Kinjo N et al: Large simple hepatic cysts leading to gastric fundal varices in a noncirrhotic patient. Fukuoka Igaku Zasshi. 104(11):449-55, 2013 3. Fischer PE et al: Laparoscopic management of a giant hepatic cyst with fibrin glue fixation of the omentum. Surg Laparosc Endosc Percutan Tech. 21(5):e273-4, 2011 4. Qiu JG et al: Laparoscopic fenestration vs open fenestration in patients with congenital hepatic cysts: a meta-analysis. World J Gastroenterol. 17(28):3359-65, 2011 5. Goodman MD et al: Laparoscopic excision of a ciliated hepatic foregut cyst. JSLS. 13(1):96-100, 2009 6. Veigel MC et al: Fibropolycystic liver disease in children. Pediatr Radiol. 39(4):317-27, 2009 7. Fukunaga N et al: Hepatobiliary cystadenoma exhibiting morphologic changes from simple hepatic cyst shown by 11-year follow up imagings. World J Surg Oncol. 6:129, 2008 8. Sharma S et al: Ciliated hepatic foregut cyst: an increasingly diagnosed condition. Hepatobiliary Pancreat Dis Int. 7(6):581-9, 2008 9. Martin DR et al: Imaging of benign and malignant focal liver lesions. Magn Reson Imaging Clin N Am. 9(4):785-802, vi-vii, 2001 10. Mortelé KJ et al: Cystic focal liver lesions in the adult: differential CT and MR imaging features. Radiographics. 21(4):895-910, 2001 11. Casillas VJ et al: Imaging of nontraumatic hemorrhagic hepatic lesions. Radiographics. 20(2):367-78, 2000

Hepatic Cyst Liver

(Left) Axial 5 mm thick CECT in a 68-year-old woman with upper abdominal discomfort shows 1 of multiple large simple cysts ; the cyst has water attenuation contents and a thin, smooth wall. (Right) Axial CT in the same case shows indistinct walls for one of the cysts , but this is due to partial volume averaging (as shown on the coronal reformatted images).

(Left) Axial CT in the same case shows mild lobulation or septation of one of the cysts . (Right) Coronal CT reconstruction in the same case shows multiple large simple cysts. These have water-density contents with no enhancement, and the walls are thin and smooth. The resolution of the image in the Z axis is somewhat limited by the relatively thick (5 mm) axial sections from which this image was reconstructed. The cysts were symptomatic due to mass effect on the stomach and other structures.

(Left) CT reformation in the same case suggests that the apparent septation of 1 cyst may represent the abutting walls of 2 cysts . (Right) Due to symptoms, the larger cysts in this same case were either opened (marsupialized) into the peritoneal cavity or resected. Note the smooth, translucent nature of the exophytic portion of the cyst wall of the excised cyst.

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Liver

Hepatic Cyst

(Left) Axial CECT shows multiple water-density hepatic lesions with no discernible walls. (Right) CT section in the same case shows that 1 of the larger cysts has a thin septum . Simple hepatic cysts are commonly multiple, and this is not necessarily evidence of autosomal dominant polycystic disease, which usually results in many more and larger cysts. Biliary hamartomas can also cause an appearance of multiple cysts, but these are rarely > 15 mm.

(Left) Axial CECT of a 69-yearold woman with right upper quadrant (RUQ) pain shows a well-circumscribed cyst with a thin wall. (Right) CT section in this patient shows a heterogeneous focus of higher attenuation within the cyst, suggestive of acute hemorrhage.

(Left) CT section in the same case shows more of the intracystic hemorrhage . (Right) CT section in this patient shows ascites that had an attenuation of about 15 HU, suggesting intraperitoneal rupture of the cyst. These findings were confirmed at surgery and the cyst was resected.

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Hepatic Cyst Liver

(Left) Axial NECT in a 45-yearold man with RUQ discomfort shows several hepatic cysts, with the largest having hyperdense material settling in a dependent position. (Right) Axial CECT in the same case shows no enhancement of the clot within the cyst. Without the NECT for comparison, it would be easy to misinterpret the clot as a mural nodularity or tumor.

(Left) Two masses are seen in the liver of a 70-year-old woman with RUQ pain, with the larger cyst having bright contents on T1WI, whereas the smaller cyst's contents are low in signal. (Right) Axial T2WI in the same case shows very bright, uniform signal within the smaller (simple) cyst , while the larger cyst's contents are more heterogeneous with mural irregularity and debris evident . Aspiration of the larger cyst yielded hemorrhagic fluid with no sign of infection or neoplasm.

(Left) Axial T1 contrastenhanced MR shows a complex cystic mass in the right hepatic lobe. The lesion contents are hypointense, as expected for simple fluid. However, there is visible thickening of the walls of the cystic mass . (Right) Axial T2WI MR in the same patient shows high-intensity simple fluid within the cyst. There was no history of malignancy, and the cyst fluid was clear on aspiration. The wall thickening is presumably the result of prior infection or hemorrhage within the cyst.

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Liver

Hepatic Cyst

(Left) Sonography in a 72-yearold man with vague upper abdominal discomfort shows a large, septate , cystic hepatic mass with accentuated throughtransmission . (Right) Axial CECT in the same case shows the septate cyst , but also shows several smaller cysts .

(Left) Axial CT in this case shows the largest cyst and several smaller cysts . (Right) On this axial CT in the same case, the gallbladder is seen . It was not evident whether the most caudal cystic lesion was an additional cyst or part of the largest septate cyst.

(Left) Coronal CT shows the largest cyst and other smaller cysts . Note the renal cyst with a calcified wall , presumably on the basis of prior hemorrhage or infection. (Right) CT reformation in the same case shows the largest septate cyst and numerous renal cysts. By imaging criteria alone, the large lesion identified by US and CT could not be differentiated from a biliary cystadenoma. However, cystadenomas are usually solitary and occur almost exclusively in women, whereas this patient is a man.

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Hepatic Cyst Liver

(Left) CT shows 1 large and many smaller hepatic cysts in this 45-year-old woman with RUQ discomfort. The largest cyst is almost 15 cm in diameter and displaces hepatic vessels. Bile ducts within the left lobe are dilated due to extrinsic compression of the left main duct. (Right) CT section shows more of the obstructed bile ducts . The mass was resected and confirmed as a simple hepatic cyst.

(Left) Axial contrast-enhanced CT shows innumerable small cystic lesions throughout the liver, ranging in size from 2-15 mm. Close attention shows that the lesions are often not perfectly spherical and many have visible nodular enhancement within their walls. (Right) US on the same patient the same day showed only the lesions > 10 mm as cystic structures whereas the smaller lesions were actually hyperechoic to background liver. This is the classic appearance of biliary hamartomas.

(Left) Axial CECT shows multiple hepatic masses that have important differences in appearance. Multiple hepatic cysts are water density and homogeneous whereas multiple foci of tumor are heterogeneous and enhancing compared with NECT images. (Right) Axial T2WI MR shows an enlarged liver with numerous large and small cysts of differing intensities in a patient with ADPLD. Cysts with high-intensity fluid also have internal septa and are the result of internal hemorrhage. Others have simple fluid .

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Liver

Hepatic Cavernous Hemangioma KEY FACTS

TERMINOLOGY • Benign tumor composed of multiple vascular channels lined by endothelial cells supported by thin fibrous stroma

IMAGING • Best clue: Mass with nodular peripheral enhancement; very hyperintense on T2WI ○ Arterial phase: Early peripheral, nodular or globular, discontinuous enhancement • Small hemangiomas (capillary): < 2 cm ○ Arterial and venous phases: Homogeneous enhancement (flash-filling) • Typical hemangiomas: 2-10 cm in diameter ○ Venous phase: Progressive centripetal enhancement to uniform filling, still isodense to blood vessels • Giant hemangioma: > 10 cm in diameter ○ Venous and delayed phases: Incomplete centripetal filling of lesion (scar does not enhance)

(Left) Graphic shows 2 hemangiomas as nonencapsulated collections of blood within enlarged sinusoidal spaces. The liver is otherwise normal. (Right) Low-power photomicrograph shows dilated vascular spaces filled with blood. Note the somewhat irregular interface between the hemangioma and the surrounding liver. (Courtesy L. Lamps, MD.)

(Left) Axial T2WI MR demonstrates a mass with marked hyperintensity, similar to that of CSF. A central scar within the mass is even more hyperintense, a typical feature of a large or giant hemangioma. (Right) Axial arterial phase T1WI MR in the same patient shows nodular, discontinuous, peripheral enhancement of the hemangioma, isointense to hepatic vessels, that persisted and progressed on subsequent phases (not shown).

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• US: Peripheral rim or homogeneously hyperechoic mass ± acoustic enhancement

TOP DIFFERENTIAL DIAGNOSES • Cholangiocarcinoma (peripheral) • Hypervascular metastases • Hepatic angiosarcoma

DIAGNOSTIC CHECKLIST • Small hepatocellular carcinomas and hypervascular metastases ○ Can mimic small hemangiomas by their uniform homogeneous enhancement pattern • Hemangiomas ○ Remain isodense to blood vessels on portal venous and delayed phases of enhancement • Other benign and malignant liver masses ○ Usually become hypodense to blood vessels and liver (except cholangiocarcinoma)

Hepatic Cavernous Hemangioma

Synonyms • Cavernous hemangioma of liver • Capillary hemangioma (small lesion)

Definitions • Benign tumor composed of multiple vascular channels lined by single layer of endothelial cells supported by thin fibrous stroma

IMAGING General Features • Best diagnostic clue ○ Peripheral nodular enhancement on arterial phase scan with slow, progressive, centripetal enhancement isodense to vessels • Location ○ Common in subcapsular area in posterior right lobe of liver • Size ○ Varies from few mm to > 20 cm ○ Giant hemangiomas: > 10 cm (arbitrary) • Morphology ○ Usually solitary and slow growing ○ May be multiple in up to 50% of cases ○ Calcification is rare (< 10%) – Usually within scar of giant hemangioma

CT Findings • NECT ○ Small (1-2 cm) and typical (2-10 cm) hemangioma – Well-circumscribed, spherical to ovoid mass isodense to blood ○ Giant hemangioma (> 10 cm) – Heterogeneous hypodense mass – Central low-density scar ± calcification • CECT ○ Small hemangiomas (capillary): < 2 cm – Arterial and venous phases: Usually show homogeneous enhancement (flash-filling) ○ Typical hemangiomas: 2-10 cm in diameter – Arterial phase: Early peripheral, nodular or globular, discontinuous enhancement – Venous phase: Progressive centripetal enhancement to uniform filling, still isodense to blood vessels – Delayed phase: Persistent complete filling ○ Giant hemangioma: > 10 cm in diameter – Arterial phase: Typical peripheral nodular, cloud-like, or globular enhancement – Venous and delayed phases: Incomplete centripetal filling of lesion (scar does not enhance) ○ Atypical hemangioma – May appear to enhance from inside in centrifugal pattern – Coronal imaging may reveal more typical centripetal enhancement pattern ○ Hyalinized (sclerosed) hemangioma – Shows minimal or no enhancement – Cannot be diagnosed with confidence by imaging

– Probably the same as "solitary necrotic nodule" described by pathologists ○ Hemangioma in cirrhotic liver – Flash-filling of small lesion may mimic hepatocellular carcinoma (HCC) □ Does not washout, unlike HCC – size and fibrosis over time □ May lose characteristic enhancement pattern □ Capsular retraction over shrunken lesion

Liver

TERMINOLOGY

MR Findings • T1WI ○ Small and typical hemangiomas – Well marginated – Isointense to blood or hypointense ○ Giant hemangioma – Hypointense mass – Central cleft-like area of marked decreased intensity (scar or fibrous tissue) • T2WI ○ Small and typical hemangiomas – Hyperintense, similar to CSF ○ Giant hemangioma – Hyperintense mass – Marked hyperintense center (scar or fibrosis) – Hypointense internal septa • T1WI C+ ○ Same enhancement pattern as on CT ○ Small hemangiomas (< 2 cm) – Homogeneous enhancement in arterial and portal phases ○ Typical and giant hemangiomas – Arterial phase: Peripheral, nodular, discontinuous enhancement – Venous phase: Progressive centripetal filling – In both phases: Isointense to blood – Central scar: No enhancement and remains hypointense

Ultrasonographic Findings • Grayscale ultrasound ○ Small hemangioma (< 2 cm) – Well-defined hyperechoic lesion ○ Typical hemangioma (2-10 cm) – Homogeneous hyperechoic mass with acoustic enhancement ○ Giant hemangioma (> 10 cm) – Lobulated heterogeneous mass with hyperechoic border ○ Atypical hemangioma – Well defined – Iso-/hypoechoic mass with hyperechoic rim • Color Doppler ○ Shows filling vessels in periphery of tumor ○ No significant color Doppler flow in center of lesion

Nuclear Medicine Findings • Tc-99m-labeled RBC scan with SPECT ○ High accuracy reported, but less proven than MR ○ Early dynamic scan: Focal defect or less uptake ○ Delayed scans (over 30-50 min): Persistent filling 773

Liver

Hepatic Cavernous Hemangioma ○ Vascular tumors (adenoma, HCC, and focal nodular hyperplasia [FNH]) – All exhibit early uptake rather than defect – May have persistent uptake on delayed scan

Imaging Recommendations • Best imaging tool ○ MR is more frequently diagnostic than CT • Protocol advice ○ Arterial, venous, and delayed scans

DIFFERENTIAL DIAGNOSIS Cholangiocarcinoma (Peripheral) • Delayed persistent enhancement; "fill-in" may mimic hemangioma • Often heterogeneous, not isodense with vessels on CT • Not as bright on T2WI • Often invades or obstructs vessels and bile ducts

Hypervascular Metastases • Usually multiple, with known primary tumor • Hyperdense in late arterial phase images ○ Might mimic capillary hemangioma • Hypo-/isodense washout on NECT and portal venous phase

Hepatic Angiosarcoma • Multiple masses throughout liver &/or spleen • Individual lesions may resemble enhancement pattern of hemangioma • More aggressive behavior; vessel invasion, metastases

PATHOLOGY General Features • Etiology ○ Occur sporadically without known predisposition • Associated abnormalities ○ Associated with FNH ○ Kasabach-Merritt syndrome – Multiple hemangiomas throughout body with thrombocytopenia

Demographics • Age ○ All age groups – More common in postmenopausal women – Uncommonly diagnosed in children • Gender ○ M:F = 1:5 • Epidemiology ○ Incidence – Ranging from 5-20% of population – Increases with multiparity ○ Prevalence: Uniform worldwide

Natural History & Prognosis • Complications (extremely rare) ○ Spontaneous rupture ○ Abscess formation • Prognosis: Usually good ○ Often show slow growth

Treatment • Asymptomatic: Usually ignore • Symptomatic large lesions: Surgical resection

DIAGNOSTIC CHECKLIST Consider

• Well-defined, blood-filled, soft nodule(s) ○ Size ranging from 2-20 cm • Cut section: Giant hemangioma ○ Areas of fibrosis, necrosis, and cystic spaces

• Small hepatocellular carcinomas and hypervascular metastases ○ Can mimic small hemangiomas by their uniform homogeneous enhancement pattern • Hemangiomas ○ Remain isodense to blood vessels on portal venous and delayed phases of enhancement • Other benign and malignant liver masses ○ Usually become hypodense to blood vessels and liver (except cholangiocarcinoma)

Microscopic Features

Image Interpretation Pearls

• Large vascular channels lined by single layer of endothelial cells separated by thin fibrous septa • No bile ducts or hepatocytes • Thrombosis of vascular channels fibrosis and calcification

• Peripheral nodular or globular enhancement on arterial phase and centripetal enhancement on venous phase ○ Useful to differentiate hemangiomas from other lesions

Gross Pathologic & Surgical Features

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Small and typical hemangioma – Usually asymptomatic – Commonly seen on routine imaging and autopsy ○ Giant hemangioma 774

– Liver enlargement, abdominal discomfort and pain • Lab data: Normal liver function tests • Diagnosis ○ Helical CECT, MR, or RBC scan with SPECT imaging is highly diagnostic ○ Atypical hemangioma (especially hyalinized) – Percutaneous or fine-needle aspiration biopsy – Comparison with prior studies that may have shown typical features of hemangioma

SELECTED REFERENCES 1. 2.

Cogley JR et al: MR imaging of benign focal liver lesions. Radiol Clin North Am. 52(4):657-82, 2014 Klotz T et al: Hepatic haemangioma: common and uncommon imaging features. Diagn Interv Imaging. 94(9):849-59, 2013

Hepatic Cavernous Hemangioma Liver

(Left) Axial venousparenchymal phase CECT shows a spherical mass with nodular, discontinuous, peripheral enhancement that is nearly isodense to blood vessels. The lesion was also isodense with blood on an unenhanced CT (not shown) and showed progressive centripetal "fill-in" on delayed CECT. (Right) Sagittal sonogram in the same patient shows a uniformly hyperechoic lesion in the peripheral right lobe, with possible acoustic enhancement , typical features of hemangioma.

(Left) On axial nonenhanced T1WI MR in a 69-year-old man with hemangioma and focal nodular hyperplasia (FNH), only the small peripheral lesion is seen, representing hemangioma. (Right) On this T2WI in the same patient, only the hemangioma is seen as hyperintense to normal liver.

(Left) On arterial phase T1WI MR in same patient, bright homogeneous enhancement of the more medial lesion is evident, typical of FNH. There is only subtle nodular, peripheral enhancement of the hemangioma . (Right) Delayed phase image in the same patient shows that the FNH is isointense with normal liver while the hemangioma is hypointense . The relatively subtle nodular enhancement of the hemangioma may be due to weak vascular enhancement by gadoxetate compared with other MR contrast agents.

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Liver

Hepatic Cavernous Hemangioma

(Left) Transverse ultrasound in a patient with a capillary hemangioma shows a small mass with a very echogenic rim. (Right) Axial NECT in the same patient shows that the mass is isodense with blood.

(Left) Axial arterial phase CECT in the same patient shows flash-filling (uniform bright enhancement) of the small hemangioma that is nearly isodense with hepatic vessels. (Right) Axial delayed phase CECT in the same patient shows that the hemangioma is still isodense to blood vessels, unlike the lesion washout that would be expected with other hepatic tumors.

(Left) Axial CECT shows an exophytic mass arising from the right lobe of the liver. The mass has a nodular, peripheral, discontinuous pattern of enhancement that is isodense to hepatic blood vessels, identifying it as a cavernous hemangioma. (Right) Coronal CECT in the same patient shows the hemangioma as "suspended" from the right lobe of the liver. The exophytic and exposed position of this lesion would make it more susceptible to trauma. This hemangioma was resected.

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Hepatic Cavernous Hemangioma Liver

(Left) Axial NECT shows a mass in the right hepatic lobe that is hyperdense to the liver, which is itself hypodense to the spleen, indicating steatosis (fatty infiltration). The mass is nearly isodense with blood pool, such as the aorta. (Right) Magnified view of the axial NECT shows the mass as a homogeneous lesion that is hyperdense to the fatty liver but isodense to blood pool.

(Left) Axial CECT in the same patient shows nodular, peripheral enhancement of the mass , with the enhanced portions remaining isodense with vessels. (Right) CECT section shows nodular peripheral enhancement, meeting diagnostic criteria for cavernous hemangioma. The presence of hepatic steatosis causes a reversal of the expected appearance of a hemangioma, which is usually expected to appear hypodense to liver on NECT.

(Left) Color Doppler ultrasound image shows 1 of several small, uniformly echogenic lesions within a normal-appearing liver. There is little apparent flow within the lesions as compared with hepatic vessels. (Right) US image shows an additional echogenic lesion . In a healthy person with no known tumor, these findings can be considered essentially diagnostic of small cavernous hemangiomas.

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Liver

Hepatic Cavernous Hemangioma

(Left) Axial NECT shows a subtle mass that is homogeneous and nearly isodense to blood vessels and liver. (Right) On arterial phase CT in the same patient, the lesion enhances heterogeneously with some areas appearing nodular or cloud-like, but not showing the typical peripheral, centripetal enhancement pattern of most hemangiomas. Note the large hepatic artery .

(Left) On another arterial phase CECT section in same patient, the enhanced portions of the mass remain isodense with blood vessels, the most characteristic feature of hemangiomas. (Right) On late venous phase CECT in the same patient, the enhanced portions of the mass remain isodense with blood vessels. This case could simulate other, more aggressive tumors, such as angiosarcoma. This lesion proved to be a benign hemangioma on additional imaging and follow-up.

(Left) Venous, parenchymal phase CECT in a 50-year-old man shows a nonenhancing but higher than water density nodule in the liver. (Right) The nonenhancing nodule is again seen in the same patient. On an abdominal MR study several years prior (not shown), this lesion had all the characteristic features of a cavernous hemangioma. Many authorities believe that "solitary necrotic nodule" is the end result of fibrosis or sclerosis of a cavernous hemangioma.

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Hepatic Cavernous Hemangioma Liver

(Left) Axial late arterial phase T1WI contrast-enhanced MR shows a small mass with solid ring enhancement, an unusual feature for cavernous hemangioma. (Right) The hemangioma in the same patient demonstrates rapid and complete fill-in on the portal venous phase image and remained isointense to blood pool on delayed phase images rather than washing out, as would be expected for most malignant hepatic masses.

(Left) Axial venousparenchymal phase CECT in a 55-year-old man with a palpable RUQ mass shows a large mass with nodular or cloud-like peripheral enhancement and a nonenhancing central scar . This was a proven giant hemangioma. (Right) Axial T2WI MR in the same patient shows a large, diffusely hyperintense giant hemangioma with a central hyperintense scar that is even more intense. Several other hemangiomas were also noted .

(Left) Axial NECT in a 36-yearold man shows a huge mass that fills the right lobe of the liver. Most of the mass is isodense with blood pool, except for a central scar that has a small focus of calcification . (Right) Axial CECT shows a huge hepatic mass occupying most of the liver. The nodular, peripheral, discontinuous enhancement identifies this as a hemangioma. Like most giant hemangiomas, it has an eccentric fibrosed scar and a focus of calcification within the scar.

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Liver

Focal Nodular Hyperplasia KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Benign tumor of liver caused by hyperplastic response to localized vascular abnormality

• Hepatic adenoma ○ Rarely retains gadoxetate on delayed phase MR • Fibrolamellar hepatocellular carcinoma ○ Usually large (> 12 cm) heterogeneous mass ○ Has "aggressive" features such as metastases • Hepatic cavernous hemangioma ○ Enhanced portions isodense to vessels • Hypervascular metastasis ○ Usually multiple with known primary tumor

IMAGING • 2nd most common benign tumor, usually in young women • Bright, homogeneously enhancing mass on arterial phase CT or MR with delayed enhancement of central scar is diagnostic of FNH • Portal venous phase scan ○ Hypodense or isodense to normal liver • Delayed scans ○ Mass: Isodense to normal liver ○ Central scar: Hyperdense or hyperintense (due to fibrous tissue) • Gadoxetate-enhanced MR ○ Most specific test to diagnose FNH ○ Prolonged enhancement of entire FNH (except scar) on delayed scan

(Left) Graphic shows a homogeneous, vascular, nonencapsulated mass with a central scar and thin radiating septa dividing the mass into hyperplastic nodules. Note the cluster of small arteries near the central scar. (Right) Axial arterial phase CECT shows bright, homogeneous enhancement of a mass with a central scar in an asymptomatic young woman who had a mass found on ultrasound. The CT findings in this case are diagnostic of FNH and require no further evaluation.

(Left) This liver wedge resection shows a wellcircumscribed nodular lesion with a central stellate scar , typical of FNH. (Courtesy M. Yeh, MD, PhD.) (Right) The central scar as well as the fibrous septa may contain thick-walled vessels . (Courtesy M. Yeh, MD, PhD.)

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DIAGNOSTIC CHECKLIST • Imaging is more reliable than histology in establishing diagnosis of FNH • Diagnosis can be made by CT alone in most cases ○ MR with gadoxetate enhancement is most specific test

Focal Nodular Hyperplasia

Abbreviations • Focal nodular hyperplasia (FNH)

Definitions • Benign tumor of liver caused by hyperplastic response to localized vascular abnormality

IMAGING General Features • Best diagnostic clue ○ Bright, homogeneously enhancing mass on arterial phase CT or MR with delayed enhancement of central scar – Hyperintense enhancement on hepatobiliary phase of gadoxetate-enhanced MR • Location ○ Usually subcapsular and rarely pedunculated • Size ○ Majority are < 5 cm unless symptomatic • Morphology ○ Spherical nonencapsulated mass • Key concepts ○ 2nd most common benign tumor of liver ○ Benign congenital hamartomatous malformation ○ Accounts for 8% of primary hepatic tumors in autopsy series ○ Usually solitary lesion (80%); multiple (20%) ○ Multiple FNHs are associated with multiorgan vascular malformations and certain brain neoplasms

CT Findings • NECT ○ Isodense or hypodense to normal liver • CECT ○ Hepatic arterial phase scan – Transient, intense, homogeneous hyperdensity ○ Portal venous phase scan – Hypodense or isodense to normal liver – Large draining veins hepatic veins ○ Delayed scans – Mass: ~ isodense to normal liver – Central scar: Hyperdense (due to fibrous tissue) – Scar visible in 2/3 of large and 1/3 of small FNHs □ "Large" > 3 cm

MR Findings • T1WI ○ Mass: Isointense to slightly hypointense ○ Central scar: Hypointense • T2WI ○ Mass: Slightly hyperintense to isointense ○ Central scar: Hyperintense • T1WI C+ ○ Arterial phase: Hyperintense (homogeneous) ○ Portal venous: Isointense to liver ○ Delayed phase – Mass: Isointense – Scar: Hyperintense

• Specific hepatobiliary MR contrast agents ○ Gadoxetate (Eovist or Primovist) – Bright, homogeneous enhancement of FNH on arterial phase – Prolonged enhancement of entire FNH on hepatobiliary phase (delayed, ~ 20 minutes) □ Intensity of FNH > liver □ Most specific test to distinguish from all other hepatic masses □ Due to functioning hepatocytes, malformed bile ductules

Liver

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Mass: Mostly homogeneous and isoechoic to liver – Occasionally hypoechoic or hyperechoic ○ Central scar: Hypoechoic • Color Doppler ○ Spoke-wheel pattern – Large central feeding artery with multiple small vessels radiating peripherally ○ Large draining veins at tumor margins ○ High-velocity Doppler signals – Due to increased blood flow or arteriovenous shunts

Angiographic Findings • Conventional ○ Arterial phase – Tumor: Hypervascular – Scar: Hypovascular – Enlargement of main feeding artery with centrifugal blood supply – Same spoke-wheel pattern as on color Doppler ○ Venous phase: Large draining veins hepatic veins ○ Capillary phase – Intense "stain" (enhancement) – No avascular zones

Nuclear Medicine Findings • Technetium sulfur colloid (TcSC) ○ Normal or increased uptake in 60% ○ Only FNH has both Kupffer cells and bile ductules ○ Almost pathognomonic if mass has uptake of TcSC • Tc-HIDA scan (hepatic iminodiacetic acid) ○ Normal or increased uptake ○ Prolonged enhancement (80%) • Tc-99m-tagged RBC scan (not useful) ○ Early isotope uptake and late defect

Imaging Recommendations • Multiphasic CT or MR is usually diagnostic ○ MR with gadolinium dimeglumine delayed scans is most specific

DIFFERENTIAL DIAGNOSIS Hepatic Adenoma • Usually heterogeneous due to hemorrhage, necrosis, or fat • Rarely has central scar • Rarely retains gadoxetate on delayed phase MR

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Liver

Focal Nodular Hyperplasia

Fibrolamellar Hepatocellular Carcinoma

– Palpable epigastric or RUQ mass ○ Other signs/symptoms – Hepatomegaly (rare, but may be interpreted as such on physical exam) ○ Lab data: Usually normal liver function tests ○ Diagnosis – Characteristic imaging findings – Core needle biopsy (include central scar)

• Usually large (> 12 cm) heterogeneous mass • Has "aggressive" features ○ Biliary, vascular, and nodal invasion ○ Metastases (70% of cases at time of diagnosis) • Large fibrous scar with calcification ○ Hypointense scar on T2WI

Hepatic Cavernous Hemangioma • Only small ones with rapid enhancement simulate FNH • CECT: Peripheral enhanced areas stay isodense with blood vessels

Hypervascular Metastasis • Multiple lesions, known primary tumor • Affects older patients • Hypodense (washout) during portal venous and delayed phases

PATHOLOGY General Features • Etiology ○ Ischemia caused by occult occlusion of intrahepatic vessels – Followed by hyperplastic response ○ Localized arteriovenous shunting caused by anomalous arterial supply ○ Oral contraceptives do not cause FNH but have trophic effect on growth • Associated abnormalities ○ FNH is more common in any liver with vascular abnormalities ○ Hepatic hemangioma (23% coexistence) ○ Hepatic adenoma ○ Multiple lesions of FNH are associated with – Brain neoplasms: Meningioma, astrocytoma – Vascular malformations of various organs

Gross Pathologic & Surgical Features • Localized, well-delineated, usually solitary (80%), subcapsular mass • Central fibrous scar in almost all; no capsule • No intratumoral calcification, hemorrhage, or necrosis

Microscopic Features • Thick-walled arteries in fibrous septa radiating from center to periphery • Proliferation and malformation of bile ducts lead to slowing of bile excretion ○ Evident on HIDA and gadoxetate-enhanced MR • Absent portal triads and central veins • Difficult differentiation from regenerative cirrhotic nodule and liver adenoma by histology

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Often asymptomatic (incidental finding in 50-90% of patients) ○ Vague abdominal pain (10-15%) due to mass effect 782

Demographics • Age ○ Common in young to middle-aged women (uncommon in men) – 3rd-4th decades of life ○ Range: 7 months to 75 years • Gender ○ M:F = 1:8 • Epidemiology ○ 4% of all primary hepatic tumors in children and adults

Natural History & Prognosis • Excellent

Treatment • Discontinuation of oral contraceptives • FNH seldom requires surgery ○ For symptomatic mass ○ Occasionally for large mass in women who wish to continue oral contraceptives or to become pregnant

DIAGNOSTIC CHECKLIST Consider • Imaging is more reliable than histology in establishing diagnosis of FNH

Image Interpretation Pearls • Immediate, intense, homogeneously enhancing lesion on arterial phase followed rapidly by isodensity on venous phase with delayed enhancement of scar ○ Gadoxetate-enhanced MR is most specific diagnostic study • Classic FNH resembles cross section of an orange (central "scar," radiating septa)

SELECTED REFERENCES 1. 2. 3.

4.

5. 6.

Cha DI et al: Clinical and imaging features of focal nodular hyperplasia in children. AJR Am J Roentgenol. 202(5):960-5, 2014 Cogley JR et al: MR imaging of benign focal liver lesions. Radiol Clin North Am. 52(4):657-82, 2014 Purysko AS et al: Characteristics and distinguishing features of hepatocellular adenoma and focal nodular hyperplasia on gadoxetate disodium-enhanced MRI. AJR Am J Roentgenol. 198(1):115-23, 2012 Berzigotti A et al: Liver hemangioma and vascular liver diseases in patients with systemic lupus erythematosus. World J Gastroenterol. 17(40):4503-8, 2011 Fowler KJ et al: Magnetic resonance imaging of focal liver lesions: approach to imaging diagnosis. Hepatology. 54(6):2227-37, 2011 Grazioli L et al: Accurate differentiation of focal nodular hyperplasia from hepatic adenoma at gadobenate dimeglumine-enhanced MR imaging: prospective study. Radiology. 236(1):166-77, 2005

Focal Nodular Hyperplasia Liver

(Left) Axial T1WI MR in a young woman with incidentally discovered FNH shows a mass that is only slightly hypointense to the normal liver. Note the hypointense central scar . (Right) Axial T2WI MR in the same patient shows the FNH as isointense to the liver whereas the central scar is hyperintense . The near isointensity of the mass to the liver on both T1 and T2WI would be very unusual for any mass other than FNH.

(Left) Axial arterial phase T1WI C+ FS MR of the same patient shows bright, homogeneous enhancement of the FNH with no early enhancement of the scar . (Right) Axial portal venous phase enhanced T1WI FS MR of the same patient shows the mass has returned to isointensity to the liver. The scar is still unenhanced but showed delayed persistent enhancement on later images (not shown) due to its fibrous content.

(Left) Coronal MIP portal venous phase CECT shows an exophytic mass that has the characteristic features of FNH, including its unique vascularity. Note the large veins on the surface of the FNH that drain into an enlarged middle hepatic vein . (Right) Coronal MIP of the same patient shows an enlarged branch of the right hepatic artery that sends a feeding vessel to the central scar region of the FNH. This case is unusual only in the exophytic location of the FNH.

783

Liver

Focal Nodular Hyperplasia

(Left) Axial nonenhanced T1WI MR of a 23-year-old man with palpable epigastric mass shows a mass that is nearly isointense with liver parenchyma and a central hypointense scar . (Right) Axial T2WI MR on the same patient shows the mass as nearly isointense to liver with a hyperintense central scar .

(Left) Late arterial phase T1WI following IV administration of gadoxetate (Eovist) shows bright, uniform enhancement of the mass , except for the central scar . (Right) Axial hepatobiliary (20-minute delayed) phase T1WI MR (same patient) shows persistent, fairly uniform retention of the "liver-specific" contrast agent within the mass , a finding diagnostic of FNH. Most cases of FNH can be diagnosed with confidence on standard multiphasic CT or MR; gadoxetate-enhanced MR is the most specific test.

(Left) Axial NECT of a 27-yearold woman with an epigastric mass shows a mass in the lateral segment that is nearly isodense with the liver. An unusual feature is a relatively large central scar, and a very rare feature is a small focus of calcification within the scar. (Right) Axial CECT of same patient shows the FNH is uniformly hypervascular on arterial phase imaging, except for the central scar. These findings, coupled with no evidence of cirrhosis, fat, or hemorrhage within the mass, favored FNH over adenoma or HCC.

784

Focal Nodular Hyperplasia Liver

(Left) Axial T1WI MR of a 28year-old woman with a mass detected on US performed for right upper quadrant pain shows the mass as nearly isointense to the liver with a hypointense central scar . (Right) On axial T2WI MR of the same patient, the mass is also nearly isointense to the normal liver whereas the scar is hyperintense .

(Left) On arterial phase axial T1WI FS MR following bolus injection of gadoxetate (Eovist) in the same patient, the FNH enhances brightly and homogeneously, except for the central scar. (Right) On this venous phase axial T1WI C+ FS MR of the same patient, the mass has returned to near isointensity with background liver, and the central scar remains hypointense.

(Left) On this hepatobiliary (20-minute delayed) phase T1WI MR, the FNH retains gadoxetate and is now homogeneously hyperintense to background liver (except for the central scar), a feature indicating the presence of functioning hepatocytes and delayed biliary clearance. These MR features are diagnostic of FNH. (Right) Photograph of the bisected, resected specimen shows the circumscribed FNH and the central fibrous scar . The FNH was resected because it was causing pain.

785

Liver

Hepatic Adenoma KEY FACTS

TERMINOLOGY • Heterogeneous group of benign hepatocellular neoplasms with distinctive genetic, pathologic, and clinical features

IMAGING • Uncommon benign neoplasm; much less common than focal nodular hyperplasia (FNH) ○ Almost all in young women with high estrogen environment, including steatosis and oral contraceptive use ○ Anabolic steroids, diabetes, and glycogen storage disease are other causes • Key features (not always present): Hypervascularity, fat content, hemorrhage, encapsulation • MR shows some elements better than CT (lipid and hemorrhage) • Gadoxetate-enhanced MR (Eovist; Primovist) ○ Adenoma shows no substantial uptake or retention ○ Key distinction from FNH

(Left) Graphic shows a hypervascular mass in the right lobe and spontaneous subcapsular bleeding . (Right) Axial CECT of a 40year-old woman with sudden RUQ pain and syncope shows an intensely enhancing mass in the right lobe of the liver. A lentiform heterogeneous collection of fluid indents the surface of the liver, and within this collection is a focus of higher density likely representing a sentinel clot. A ruptured inflammatory hepatic adenoma was resected.

(Left) Photograph of a resected specimen shows a large adenoma with central areas of rupture and hemorrhage . (Courtesy M. Yeh, MD, PhD.) (Right) Photomicrograph of a hepatic adenoma features a thinwalled unpaired vessel surrounded by neoplastic hepatocytes with abundant steatosis. Imaging often reveals these features, directly or indirectly. (Courtesy M. Yeh, MD, PhD.)

786

• T1WI: Mass: Heterogeneous signal intensity ○ Increased signal intensity (due to fat or recent hemorrhage) ○ Decreased signal intensity (necrosis, calcification, old hemorrhage) • Heterogeneous, hypervascular mass with foci of fat or hemorrhage in a young woman

TOP DIFFERENTIAL DIAGNOSES • • • •

Hepatocellular carcinoma (HCC) Fibrolamellar HCC Focal nodular hyperplasia Hypervascular metastases

CLINICAL ISSUES • Risk factors for HCC ○ Large adenoma, male sex, glycogen storage disease, anabolic steroid use, CTNNB1-mutated subtype of HA

Hepatic Adenoma

Abbreviations

○ Adenoma shows no substantial uptake or retention on delayed imaging – Key distinction from FNH

• Hepatic adenoma (HA)

Ultrasonographic Findings

Synonyms

• Grayscale ultrasound ○ Complex, hyper-/hypoechoic, heterogeneous mass with anechoic areas – Due to fat, hemorrhage, necrosis, and calcification – Capsule may be seen

• Hepatocellular adenoma, liver cell adenoma

Definitions • Heterogeneous group of benign hepatocellular neoplasms with distinctive genetic, pathologic, and clinical features

IMAGING General Features • Best diagnostic clue ○ Heterogeneous, hypervascular mass with foci of fat or hemorrhage in a young woman • Location ○ Subcapsular region of right lobe of liver (75%) ○ Intraparenchymal or pedunculated (10%) • Size ○ Varies from 6-30 cm • Key concepts ○ Very uncommon relative to focal nodular hyperplasia (FNH) and hepatocellular carcinoma (HCC) ○ 3 distinct subtypes with different genetics, pathology, clinical features

CT Findings • Depending on HA subtype ○ Encapsulation seen in ~ 20%, best on delayed phase CECT ○ Hemorrhage within tumor, best seen on NECT as hyperdense foci ○ Intratumoral lipid, best seen on NECT as hypodense foci ○ Hypervascularity – Most intense and persistent in inflammatory subtype of HA ○ Calcification: Focal, present in ~ 5%

MR Findings • T1WI ○ Mass: Heterogeneous signal intensity – Increased signal intensity (due to fat and recent hemorrhage), more evident on MR than CT – Decreased signal intensity (necrosis, calcification, old hemorrhage) ○ Rim (fibrous pseudocapsule): Hypointense • T2WI ○ Mass: Heterogeneous signal intensity – Increased signal intensity (old hemorrhage, necrosis) – Decreased signal intensity (fat, recent hemorrhage) ○ Rim (fibrous pseudocapsule): Hypointense • T1WI C+ ○ Gadolinium, arterial phase – Heterogeneous hypervascular enhancement (especially in inflammatory subtype) ○ Delayed phase – Pseudocapsule: Hyperintense to liver and adenoma • Gadoxetate-enhanced MR (Eovist, Primovist)

Liver

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ Gadoxetate-enhanced MR, including multiphasic and delayed imaging ○ In- and opposed-phase GRE

DIFFERENTIAL DIAGNOSIS Hepatocellular Carcinoma • May be hard to distinguish on imaging or pathology • Biliary, vascular, nodal invasion and metastases = malignancy • HCC typically occurs in older, cirrhotic men ○ Adenoma occurs in young, healthy women

Fibrolamellar HCC • Large, lobulated mass with scar and septa • Vascular, biliary invasion and metastases common

Focal Nodular Hyperplasia • Arterial phase: Homogeneously enhancing mass • All other phases: Isodense to normal liver • Uniformly retains gadoxetate on delayed phase MR

Hypervascular Metastases • Usually multiple; look for primary tumors ○ Breast, thyroid, kidney, and endocrine

PATHOLOGY General Features • Etiology ○ risk in oral contraceptive and anabolic steroid users ○ Pregnancy increases growth rate and risk of rupture ○ Hepatic steatosis growth and number of adenomas ○ Diabetes mellitus ○ von Gierke type I glycogen storage disease – Multiple adenomas in 60% of affected patients

Staging, Grading, & Classification • Proposed new classification based on genetics, pathology, and tumor biology • 3 distinct subtypes ○ Inflammatory HA – Most common subtype (40-50%) – Includes those previously called "telangiectatic HA" – Occur in young women on oral contraceptives and obese women – 60% have mutation of IL6ST gene with altered glycoprotein metabolism

787

Liver

Hepatic Adenoma

– MR: No excessive fat or lipid within masses; persistent hypervascularity through arterial and venous phases due to sinusoidal dilation, peliotic areas, and abnormal vessels □ Bright on T2WI □ Likely to show MR (and clinical) evidence of hemorrhage (up to 30%) □ 10% estimated likelihood of malignant degeneration to HCC ○ HNF1A-mutated HA – 2nd most common subtype (30-35% of HAs) – Association with diabetes and familial hepatic adenomatosis – Exclusively in women; 90% have history of oral contraceptive use – Mutated HNF1A gene promotes lipogenesis and hepatocellular proliferation – MR: Diffuse lipid deposition within HAs □ Most evident as signal dropout on opposed-phase GRE T1WI □ Macroscopic fat deposits are less common □ Only moderate enhancement on arterial phase; no persistent enhancement on venous and delayed – Least aggressive subtype □ HAs of this subtype < 5 cm rarely bleed and have minimal risk of HCC ○ CTNNB1-mutated HA – Least common subtype (10-15% of HAs) – Subtype most likely to occur in men, those taking androgenic steroids, and in patients with glycogen storage disease □ Also associated with metabolic syndrome – Mutation of CTNNB1 disrupts hepatocyte proliferation, growth, adhesion, etc. – This subtype carries highest risk of malignant transformation (> 10%) – MR features: No distinctive pattern established □ Usually hypervascular with evidence of hemorrhage or necrosis within tumor ○ Unclassified HA subtype – Does not fit other profiles of HA subtypes

Gross Pathologic & Surgical Features • Well-circumscribed mass within noncirrhotic liver ○ Foci of fat, hemorrhage, infarction ○ Pseudocapsule and occasional pseudopods • Adenomatosis ○ No strict definition (generally > 10 adenomas) ○ Associated with glycogen storage disease, steatosis, and diabetes ○ May number > 100 adenomas – May cause hepatic dysfunction, hemorrhage

Microscopic Features • • • • •

788

Sheets or cords of hepatocytes Absence of portal and central veins and bile ducts Increased amounts of glycogen and lipid Scattered, thin-walled, unpaired, vascular channels Few scattered Kupffer cells

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ RUQ pain (40%): Due to hemorrhage ○ Asymptomatic (20%) – Especially those with HNF1A type ○ No elevation of serum -fetoprotein • Diagnosis: Biopsy and histology

Demographics • Age ○ Young women in childbearing age group ○ Predominantly in 3rd and 4th decades • Gender ○ 98% seen in females – Not seen in males unless on anabolic steroids or with glycogen storage disease

Natural History & Prognosis • Complications ○ Hemorrhage: Intrahepatic or intraperitoneal (40%) ○ May regress on withdrawal of oral contraceptives • Risk factors for degeneration into HCC ○ Male gender (10x more frequent than in women on per case basis) ○ Concomitant glycogen storage disease ○ Anabolic steroid use ○ CTNNB1-mutated subtype of HA ○ HA mass size > 5 cm • Prognosis ○ Usually good – After discontinuation of oral contraceptives – After surgical resection of large or symptomatic HAs ○ Poor – Intraperitoneal rupture – Rupture during pregnancy – Malignant transformation – Adenomatosis (> 10 adenomas) □ May hemorrhage, impair hepatic function

Treatment • Adenoma < 5 cm ○ Observation and discontinuation of oral contraceptives or other steroids • Adenoma > 5 cm and near surface ○ Surgical resection ○ Consider transcatheter embolization • Pregnancy should be avoided due to risk of rupture • Transplantation for some cases of adenomatosis

SELECTED REFERENCES 1. 2. 3.

Cogley JR et al: MR imaging of benign focal liver lesions. Radiol Clin North Am. 52(4):657-82, 2014 De Kock I et al: Hepatic adenomatosis: MR imaging features. JBR-BTR. 97(2):105-8, 2014 Grazioli L et al: Hepatocellular adenoma and focal nodular hyperplasia: value of gadoxetic acid-enhanced MR imaging in differential diagnosis. Radiology. 262(2):520-9, 2012

Hepatic Adenoma Liver

(Left) Venous phase CECT of an 18-year-old girl injured in a vehicle crash shows a subcapsular, encapsulated mass that is not very vascular, a typical (but not diagnostic) feature of the HNF1A-mutated subtype of hepatic adenoma. (Right) An axial fat-suppressed T2WI in the same patient shows the mass as almost isointense to background liver with a thin hyperintense capsule , typical features of an HNF1Amutated subtype of hepatic adenoma.

(Left) T1-weighted in-phase MR in the same case shows a uniform iso- to slightly hyperintense peripheral liver lesion with a thin low-intensity capsule . (Right) An opposed-phase GRE T1WI in the same case shows marked signal loss from the mass , which indicates the presence of diffuse lipid, another typical feature of this subtype of hepatic adenoma.

(Left) On this delayed phase image in the same case, obtained after IV administration of gadoxetate (Eovist, Primovist), the normal liver enhances brightly whereas the mass shows no retained contrast, which indicates that it lacks functioning bile ductules and differentiates it from a focal nodular hyperplasia (FNH). (Right) Photograph of the resected specimen, an HNF1Amutated subtype of hepatic adenoma, shows an encapsulated, pale, tan mass with diffuse and focal lipid .

789

Liver

Hepatic Adenoma

(Left) Axial T1WI GRE in-phase MR in a 54-year-old woman who had a liver mass detected on CT shows the mass as slightly hyperintense to a normal-appearing liver. On opposed-phase GRE MR (not shown), there was no signal dropout from the lesion, indicating no lipid content. (Right) On T2WI MR in the same case, the mass is slightly hyperintense to the liver, and a central scar is quite hyperintense.

(Left) On MR sections in the same case taken after bolus injection of gadoxetate (Eovist) the mass is hypervascular whereas the central scar is hypointense . The mass and central scar were nearly isointense on the venous phase images (not shown). (Right) On a 20minute delayed image in the same case the mass retains less contrast material than normal liver. Because there was concern that the lesion was not a typical FNH, it was resected.

(Left) Photo of the gross pathology specimen shows an encapsulated mass with blood pooling and foci of hemorrhage. (Right) Histologic specimen in the same case shows disorganized hepatocytes with abundant eosinophilic nuclei on H&E staining, unpaired blood vessels distributed haphazardly throughout the lesion, and foci of chronic inflammation . The final diagnosis was hepatic adenoma of the inflammatory subtype. (Courtesy T. Longacre, MD.)

790

Hepatic Adenoma Liver

(Left) Axial T1WI of a 35-yearold woman with RUQ pain shows a hepatic mass containing several hyperintense foci that represent hemorrhage. (Right) Axial T1WI shows more hyperintense foci of hemorrhage within the hypointense mass .

(Left) Axial T2WI in the same case shows a heterogeneous mass with some foci of slight hyperintensity that represent lipid. (Right) Axial portal venous phase T1WI in the same case shows persistent hypervascular enhancement in the nonnecrotic and nonhemorrhagic portions of the mass, typical features of the inflammatory subtype of hepatic adenoma, which was confirmed on resection.

(Left) Axial NECT shows a very large, sharply demarcated, mostly homogeneous mass with a small focus of hemorrhage . (Right) Axial arterial phase CECT in the same patient shows hypervascularity with enlarged vessels within and on the surface of the tumor. Note the large hepatic artery . Hepatic adenomas of the inflammatory subtype are usually heterogeneously hypervascular and often encapsulated with focal hemorrhage, as in this patient.

791

Liver

Hepatic Adenoma

(Left) Axial opposed-phase GRE T1WI MR shows an encapsulated mass with hyperintense foci representing hemorrhage or fat. The in-phase images showed increased signal within the mass. (Right) Axial fat-suppressed T2WI MR in the same patient shows that the mass is nearly isointense to the liver with a central focus of hyperintensity (hemorrhage). Fat content would have shown signal dropout on this sequence. A capsule or pseudocapsule is seen in ~ 20% of adenomas.

(Left) Axial CT during the arterial phase of enhancement shows a brightly enhancing mass with a focal calcification , the latter being a less common feature of adenomas. (Right) Ultrasound in the same case confirms the solid mass with calcification and shows a capsule around the mass. The capsule is a common feature and the focal calcification a less common feature of adenomas, as was proven in this case.

(Left) Arterial phase T1WI contrast-enhanced MR of a 32year-old woman who had been using oral contraceptives for 14 years shows 1 of about 10 encapsulated, enhancing focal masses . (Right) More adenomas are seen on this section. In the absence of chronic liver disease or a known malignancy, these findings were considered diagnostic of adenomas. Following cessation of oral contraceptive use, these adenomas decreased in size and number within 4 months.

792

Hepatic Adenoma Liver

(Left) Axial NECT of a 37-yearold man with type I glycogen storage disease and multiple adenomas shows hepatomegaly and lowattenuation masses within the liver. The low attenuation is due to intratumoral lipid. These are foci of the CTNNB1mutated subtype of hepatic adenoma. (Right) A hepatic arterial phase image in the same patient shows that some lesions are hypervascular whereas others show heterogeneous enhancement .

(Left) Portal venous phase image in the same case shows capsular enhancement or compressed hepatic parenchyma around most of the adenomas . Adenomas are usually multiple in the setting of type I or III glycogen storage disease and carry a high risk of malignant degeneration, especially those > 5 cm in diameter and those in men. (Right) Photograph of the resected specimens in a case of hepatic adenomatosis shows multiple adenomas with hemorrhage and necrosis. (Courtesy M. Yeh, MD, PhD.)

(Left) Axial CECT shows a large heterogeneous hepatic mass with several foci measuring less than water attenuation, indicating fat content. Also noted are foci of calcification . Serial CT scans had shown slow growth of the mass over 7 years. (Right) Gross pathology from the same case shows the mass with foci of fat and hemorrhage . Histology revealed foci of HCC within this adenoma, which had the CTNNB1 mutation, as did the foci of HCC.

793

Liver

Biliary Hamartoma KEY FACTS

TERMINOLOGY • Uncommon benign malformations of biliary tract ○ a.k.a. von Meyenburg complex ○ Asymptomatic and of no clinical concern

IMAGING • Multiple, near water density/intensity liver lesions < 15 mm in diameter ○ Varied enhancement based on cystic and solid components ○ No communication with biliary tree • US: Small and well-circumscribed lesions ○ Often have echogenic walls with small fluid content • US shows much more echogenicity and fewer cystic lesions than anticipated based on prior CT or MR

TOP DIFFERENTIAL DIAGNOSES • Autosomal dominant polycystic liver disease ○ Larger, more numerous cysts in liver and other organs

(Left) Axial T2WI MR shows innumerable tiny bright foci throughout the liver , representing biliary hamartomas. This patient also had evidence of congenital hepatic fibrosis on imaging and liver biopsy, both part of the congenital hepatic and renal fibropolycystic disease spectrum. (Right) MRCP shows small spherical cyst-like lesions that do not communicate with the (normal) biliary tree. This feature helps to distinguish biliary hamartomas from Caroli disease.

(Left) Sonographic image shows innumerable tiny echogenic foci throughout the liver and 1 of ~ 10 cyst-like lesions , though even these have small foci of echogenicity within the wall. MR on this patient showed many more cystic-appearing biliary hamartomas. (Right) The branching, angulated glands in biliary hamartomas are lined by a single layer of flattened cuboidal epithelium. These glands may expand or rupture to produce small "cysts." There is no nuclear atypia. (Courtesy S. Kakar, MD.)

794

• Multiple simple hepatic cysts ○ Fewer cysts of varying size; no mural nodules • Caroli disease ○ Central dot sign on CECT and MR ○ ERCP and MRCP: Communicating bile duct abnormality • Multiple/solitary, small metastatic lesions ○ More complex and varied in size • Opportunistic infection (microabscesses) ○ Must be considered in immunosuppressed patient with fever

DIAGNOSTIC CHECKLIST • No further evaluation needed when seen as isolated finding in healthy, nononcologic patient • Should be considered as likely diagnosis in setting of innumerable small, slightly complex "cysts" in healthy patient • Lesions appear more echogenic than expected on sonography

Biliary Hamartoma

Caroli Disease

Definitions

• Multiple, small, rounded, hypodense/hypointense (T1WI), saccular dilatations of intrahepatic ducts • Central dot sign on CECT and MR • ERCP and MRCP: Communicating bile duct abnormality

• Uncommon benign malformations of biliary tract

Multiple/Solitary Small Metastatic Lesions

Synonyms • von Meyenburg complex

IMAGING

• Metastases are more varied in size and distribution, more mural nodularity and complexity

General Features

Opportunistic Infection (Microabscesses)

• Best diagnostic clue ○ Multiple near water density/intensity liver lesions < 15 mm in diameter • Irregular spherical • Usually multiple to innumerable

• Must consider in immunosuppressed patient with fever • Difficult to distinguish by imaging alone; need aspiration/biopsy

CT Findings

General Features

• CECT ○ Cystic components remain near water density – No enhancement of contents ○ Solid (fibrous stroma) components enhance ○ Punctate calcifications may be seen

• Etiology ○ Congenital malformation of bile ducts ○ Considered part of spectrum of fibropolycystic disease of liver and kidneys – May coexist in multiple forms in same patient □ Autosomal dominant (or recessive) polycystic disease □ Caroli disease □ Congenital hepatic fibrosis □ Choledochal cyst

MR Findings • T1WI ○ Hypointense (both cystic and solid lesions) • T2WI ○ Very hyperintense (cystic components) ○ Intermediate intensity (solid lesions) ○ Heavily T2WI: Remain hyperintense (equal to fluid) • T1WI C+ ○ No enhancement of cystic components – ± nodular enhancement of fibrous nodules • MR cholangiography (MRC) ○ Markedly hyperintense lesions ○ No communication with biliary tree

Ultrasonographic Findings • Grayscale ultrasound ○ Multiple small and well-circumscribed lesions ○ Fibrotic parts of lesions are very echogenic – Fluid or cystic component is sonolucent □ ± posterior acoustic enhancement – US shows much more echogenicity and fewer cystic lesions than anticipated based on prior CT or MR

PATHOLOGY

Microscopic Features • Noncommunicating ducts and glands embedded within dense fibrous stroma

CLINICAL ISSUES Presentation • Asymptomatic with normal liver function

Demographics • Epidemiology ○ More common than realized; up to 3% of general population; M = F; any age

Treatment • No treatment needed for biliary hamartomas

DIAGNOSTIC CHECKLIST

Imaging Recommendations

Consider

• Best imaging tool ○ Thin section, multiplanar CECT or MR

• MRC to differentiate biliary hamartomas from other biliary or cystic abnormalities

DIFFERENTIAL DIAGNOSIS Autosomal Dominant Polycystic Liver Disease • Larger and more numerous hepatic cysts • Usually have cysts in kidneys and other organs

Multiple Simple Hepatic Cysts • Rarely as numerous or limited to small size as biliary hamartomas • US: Anechoic lesion with increased through transmission; no mural nodularity

Liver

TERMINOLOGY

Image Interpretation Pearls • Should be considered as likely diagnosis in setting of multiple small, slightly complex "cysts" in healthy patient • Lesions appear more echogenic than expected on US

SELECTED REFERENCES 1. 2.

Lin S et al: A study of multiple biliary hamartomas based on 1697 liver biopsies. Eur J Gastroenterol Hepatol. 25(8):948-52, 2013 Tohmé-Noun C et al: Multiple biliary hamartomas: magnetic resonance features with histopathologic correlation. Eur Radiol. 18(3):493-9, 2008

795

Liver

Biliary Hamartoma

(Left) Axial CECT of a 76-yearold woman with a history of renal cancer shows innumerable, tiny hypodense lesions throughout the liver. Incidental note is made of surgical clips from the prior nephrectomy. These biliary hamartomas should not be mistaken for metastases. (Right) Axial CT in the same patient shows more of the lesions that almost certainly represent biliary hamartomas. These have remained stable for years, and the patient is not immunosuppressed.

(Left) CT section in the same case shows the relatively uniform size of these small lesions. Careful attention to thin sections through the larger lesions shows mural nodularity . (Right) Transverse sonogram in the same patient, performed the same day as the CT scan, shows only a few "cystic" lesions , while there are innumerable tiny echogenic foci throughout the liver that correspond to the smaller biliary hamartomas, which presumably contain relatively more fibrous tissue and less fluid.

(Left) CT in a patient with chronic viral hepatitis shows innumerable small cystic lesions, some with nodularity and irregularity of the "cyst" walls . These are typical findings for biliary hamartomas and would be a very rare (unreported) feature of hepatocellular carcinoma (HCC). (Right) Transverse US of the same patient shows 1 of several echogenic foci and many more cystic lesions . None of these lesions showed interval change on subsequent imaging studies over several years and likely represent biliary hamartomas.

796

Biliary Hamartoma Liver

(Left) Axial CECT shows innumerable small (≤ 15 mm in diameter) hepatic lesions of near water density throughout the liver. They have remained stable and asymptomatic and are presumed to represent biliary hamartomas. The patient has no evidence of polycystic disease. (Right) Axial CECT in the same patient shows more biliary hamartomas. In the absence of cancer history, biopsy proof is not necessary in most cases.

(Left) Axial CECT shows multiple tiny, distinct, hypodense lesions throughout the liver, too small to permit accurate density measurements. In a healthy, nononcologic patient, they likely represent biliary hamartomas. (Right) Axial NECT in an asymptomatic patient shows innumerable subcentimeter, hypodense foci in both lobes of the liver. A liver biopsy confirmed the diagnosis of biliary hamartomas.

(Left) Axial T2WI MR shows high-intensity, small biliary hamartomas . This patient also had an enlarged, dysmorphic liver and supernumerary and enlarged hepatic arteries as signs of congenital hepatic fibrosis. (Right) T2WI MR in the same patient shows larger cystic lesions that communicate with the biliary tree and represent aberrant bile duct cysts of Caroli disease. Congenital hepatic fibrosis, Caroli disease, and biliary hamartomas are all manifestations of fibropolycystic disease.

797

Liver

Hepatic Angiomyolipoma and Lipoma KEY FACTS

TERMINOLOGY • Benign mesenchymal tumor composed of variable amounts of smooth muscle (myoid), fat (lipoid), and proliferating blood vessel (angioid) components

IMAGING • Best diagnostic clue: Well-circumscribed, mostly fatty mass in liver ○ Only 50% of hepatic angiomyolipomas have substantial fat component • Arterial phase: Prominent enhancement of nonfatty portion of lesion ○ Central vessels within lesion if mass is large • Fatty component of tumor results in hyperintense (high signal) foci on T1WI and T2WI • MR, fat suppression ± opposed-phase GRE imaging

TOP DIFFERENTIAL DIAGNOSES • Hepatocellular carcinoma

(Left) Gross photograph of a fixed specimen shows a heterogeneous mottled tan, yellow, and brown tumor with areas of hemorrhage and degeneration . Note that the background liver is not cirrhotic. (Courtesy J. Misdraji, MD.) (Right) H&E-stained section shows a tumor composed of 3 elements: Adipose tissue , vessels , and plump spindle cells . (Courtesy J. Misdraji, MD.)

(Left) Axial T2WI MR shows a heterogeneously bright mass with a fatty component that is nearly isointense to subcutaneous fat . The rest of the tumor has the moderate hyperintensity typical of most neoplasms on T2WI MR. (Right) Axial T1WI MR in the same patient shows that most of the mass is hyperintense, an unusual feature of most neoplasms and generally indicative of the presence of fat or hemorrhage within the mass. This tumor was resected and proved to be an isolated angiomyolipoma (AML).

798

• • • • •

Postoperative state, liver Focal steatosis Hepatic adenoma Hepatic lipoma Metastases ○ Teratoma or liposarcoma

PATHOLOGY • Associated with tuberous sclerosis in < 10% of cases ○ But some patients likely have forme fruste tuberous sclerosis

DIAGNOSTIC CHECKLIST • Small, fat density hepatic mass in patient with tuberous sclerosis is almost certainly benign • Angiomyolipoma that is primarily myeloid or angioid may be indistinguishable from other hepatic tumors, including hepatocellular carcinoma

Hepatic Angiomyolipoma and Lipoma

Abbreviations • Hepatic angiomyolipoma (AML)

Definitions • Benign mesenchymal tumor composed of variable amounts of smooth muscle (myoid), fat (lipoid), and proliferating blood vessel (angioid) components

IMAGING General Features • Best diagnostic clue ○ Well-circumscribed, mostly fatty mass in liver • Location ○ Liver is 2nd most common site (kidney is 1st)

CT Findings • NECT ○ Well-defined mass with heterogeneous attenuation values due to presence of fat and soft tissue densities – May be almost completely fat or soft tissue density mass • CECT ○ Arterial phase: Prominent enhancement of nonfatty portion of lesion

MR Findings • T1WI ○ Fatty component of tumor results in hyperintense (high signal) foci on T1WI ○ Relative loss of signal intensity on opposed-phase images compared with in-phase ○ Frequency-selective fat-saturation techniques are useful • T2WI ○ High signal intensity of fatty components ○ Heterogeneous hyperintensity • T1WI C+ ○ Enhancement of soft tissue elements within lesion

Imaging Recommendations • Best imaging tool ○ MR with fat suppression ± opposed-phase GRE imaging

DIFFERENTIAL DIAGNOSIS

• Typically seen in young women who take oral contraceptives

Hepatic Lipoma • No enhancement on CECT (indistinguishable from AML with mostly fat content)

Metastases (Teratoma or Liposarcoma) • Fat containing, ± fluid, calcification in teratoma • Most liposarcomas are large, well-circumscribed, vascular structures with soft tissue attenuation

PATHOLOGY General Features • Associated abnormalities ○ Associated with tuberous sclerosis (TS) in < 10% of cases – AMLs (+ cysts) in kidneys, plus extrarenal masses – Some patients likely have forme fruste of TS

Gross Pathologic & Surgical Features • Fat content varies from < 10% to > 90% of tumor volume • May have large foci of necrosis

Microscopic Features • Epithelioid smooth muscle cells, admixture of mature fat cells, and proliferating blood vessels

CLINICAL ISSUES Presentation • Asymptomatic and discovered incidentally at imaging • Pain results from intratumoral hemorrhage (rare)

Demographics • Gender ○ Marked female predominance

Natural History & Prognosis • Spontaneous hemorrhage or rupture (rare) • No malignant potential

Treatment • Conservative; embolization ○ Resect large peripheral lesions and those of uncertain histology

DIAGNOSTIC CHECKLIST

Hepatocellular Carcinoma (HCC)

Consider

• Fat within tumor may be localized or show diffusely scattered or mosaic pattern • Fat-containing mass in cirrhotic liver is usually HCC

• Small, fat density hepatic mass in patient with TS is likely benign

Postoperative State, Liver • Omental fat may be placed into surgical defect in liver

SELECTED REFERENCES 1.

Focal Steatosis • Often periligamentous or periportal distribution • Shows normal blood vessels traversing lesion

2. 3.

Hepatic Adenoma • Well defined, often surrounded by capsule • Heterogeneously hypervascular; areas of hemorrhage and fat within

Liver

TERMINOLOGY

4.

Wang SY et al: Comparison of MRI features for the differentiation of hepatic angiomyolipoma from fat-containing hepatocellular carcinoma. Abdom Imaging. 39(2):323-33, 2014 Lafitte M et al: Radiologic-pathologic correlation in liver angiomyolipoma in a 68-year-old woman. Diagn Interv Imaging. 94(11):1161-4, 2013 Chang Z et al: Characteristics and treatment strategy of hepatic angiomyolipoma: a series of 94 patients collected from four institutions. J Gastrointestin Liver Dis. 20(1):65-9, 2011 Prasad SR et al: Fat-containing lesions of the liver: radiologic-pathologic correlation. Radiographics. 25(2):321-31, 2005

799

Liver

Hepatic Angiomyolipoma and Lipoma

(Left) Axial NECT of a 56-yearold man who presented with nonspecific symptoms and no clinical evidence of tuberous sclerosis shows 1 of several partially fat-density masses in the liver. (Right) Axial NECT of the same patient shows a fatdensity mass and simple cysts in the kidneys.

(Left) Axial CECT of the same patient shows bright enhancement of a portion of the hepatic mass that has other components measuring fat density . (Right) Axial CECT of the same patient shows that most of the hepatic mass is hypervascular with large feeding vessels .

(Left) Axial CECT of the same patient shows a renal mass that is also characterized by large vessels and macroscopic fat, which are characteristic features of AML. This patient probably has a forme fruste of tuberous sclerosis with incomplete or atypical clinical manifestations. (Right) H&Estained section shows epithelioid smooth muscle cells with a rarefied cytoplasm that resembles "spider webs." Note the enlarged oval nuclei and distinct nucleoli . (Courtesy J. Misdraji, MD.)

800

Hepatic Angiomyolipoma and Lipoma Liver

(Left) Axial CECT of a 36-yearold woman with tuberous sclerosis (TS) shows 2 nodules within the liver. One of them has the fat-density characteristic of AML, but the other is of soft tissue density likely representing lipidpoor AML. (Right) Axial CECT of the same patient shows that the right kidney is absent (removed due to spontaneous hemorrhage from an AML). The left kidney is distorted by multiple fat-containing AMLs . This patient also had lymphangiomyomatosis of the lungs, another feature of the TS complex.

(Left) This 43-year-old woman had vague RUQ discomfort. Axial NECT shows a large hepatic mass with small foci of fat density . (Right) Axial CECT in the same patient shows marked hypervascularity of the tumor, raising concern for hepatic adenoma or a malignant tumor. The mass was resected and proved to be an AML with predominantly smooth muscle and vascular components.

(Left) The resected specimen in this case is a large mass that had small foci of fat, large blood vessels, and areas of necrosis . (Right) The bivalved resected specimen was a large mass, the center of which had become necrotic and "shelled out" on cross sectioning. The final diagnosis was hepatic AML.

801

Liver

Hepatic Inflammatory Pseudotumor KEY FACTS

• Heterogeneous group of lesions occurring in liver and bile ducts (among other organs) characterized by fibroblastic and myofibroblastic proliferation with inflammatory infiltrate

○ Cholangiocarcinoma (peripheral) ○ Hepatocellular carcinoma ○ Hepatic metastases and lymphoma • Hilar biliary stricture or mass ○ Cholangiocarcinoma (hilar cholangiocarcinoma)

IMAGING

CLINICAL ISSUES

• 2 main types that mimic cholangiocarcinoma ○ Large, solitary, peripheral mass, often with hyperdense delayed contrast enhancement ○ Small mass in hepatic hilum appearing identical to Klatskin tumor (short segment stricture with dilation of ducts upstream)

• Percutaneous core biopsy is needed for definite diagnosis ○ May suffice for diagnosis of peripheral hepatic type ○ Has not provided confident diagnosis in biliary type • May respond to steroids and other anti-inflammatory medications ○ Especially if due to IgG4-related sclerosing disease

TOP DIFFERENTIAL DIAGNOSES

DIAGNOSTIC CHECKLIST

• IgG4-related sclerosing disease (IgG4-RD) ○ Probable cause of many reported cases of inflammatory pseudotumor • Peripheral hepatic mass

• Look for imaging, clinical, and laboratory (serum IgG4 levels) evidence of IgG4-RD

TERMINOLOGY

(Left) CECT in the portal venous-parenchymal phase shows an infiltrating tumor that encases and narrows the right portal vein. (Right) Axial PET/CT in the same patient shows an FDG-avid mass in the hilum, extending along the right portal vein. The bile ducts were obstructed at the hilum, requiring a biliary stent . This was interpreted as a cholangiocarcinoma, but surgical resection (right hepatectomy) showed only inflammatory pseudotumor of the liver and bile ducts.

(Left) Venous phase CECT in a 55-year-old man with hepatic dysfunction shows a hepatic mass with central necrosis and retraction of the overlying hepatic capsule . (Right) Delayed phase CT in this case shows persistent retention of contrast and retraction of the hepatic capsule . While this CT appearance is very suggestive of peripheral cholangiocarcinoma in every aspect, the resected mass proved to be an inflammatory pseudotumor.

802

Hepatic Inflammatory Pseudotumor

Synonyms • Biliary inflammatory pseudotumor • Inflammatory myofibroblastic tumor (IMT)

Definitions • Heterogeneous group of lesions occurring in liver and bile ducts (among other organs) characterized by fibroblastic and myofibroblastic proliferation with inflammatory infiltrate

IMAGING General Features • Best diagnostic clue ○ 2 main types with distinctive morphologic features – Large, solitary, peripheral mass; heterogeneous and delayed enhancement □ Imaging features similar to intrahepatic (peripheral) cholangiocarcinoma – Small mass in hilum with obstruction of main intrahepatic bile ducts □ Imaging features identical to hilar (Klatskin) cholangiocarcinoma • Location ○ More common in periphery of liver ○ Less common in main bile ducts, near confluence • Size ○ Peripheral mass type – Large; 2-14 cm – Rarely multiple masses ○ Hilar type – Small or nondetectable mass – Wall thickening and luminal narrowing of bile ducts near bifurcation

Imaging Recommendations • Best imaging tool ○ Triphasic CT or MR – Plus cholangiography for biliary variant • Protocol advice ○ Include delayed phase imaging to detect persistent retention of contrast material – 10-minute delay

□ Central necrosis is seen in many – Persistent, hyperdense enhancement on delayed phase CECT □ Correlates with foci and extent of fibrous stroma within mass – ± retraction of overlying hepatic capsule □ Mimics pattern seen in peripheral cholangiocarcinoma – May be encapsulated ○ Hilar mass or stricture – Stricture of bile ducts at confluence (or more diffusely) – Small mass ± delayed, persistent enhancement

MR Findings • Peripheral mass ○ T1WI: Commonly hypointense to liver ○ T2WI: Iso- to slightly hyperintense to liver ○ T1WI C+: Variable enhancement pattern – Homogeneous, heterogeneous, peripheral, ± internal enhancement – Delayed, persistent enhancement on 10-minute series following gadolinium-based contrast administration □ Corresponds to fibrous stroma • Hilar mass or stricture ○ Short stricture, high-grade narrowing shown on MRCP ○ Findings identical to those with Klatskin tumor (or PSC)

Ultrasonographic Findings • Heterogeneous hyper-/hypoechoic mass • through-transmission for tumors with homogeneous stroma • echogenicity corresponds to predominantly fibrotic areas • echogenicity corresponds to predominantly cellular areas

Nuclear Medicine Findings • PET/CT ○ Sites of inflammatory pseudotumor may be FDG avid – Not necessarily helpful in distinguishing from hilar or peripheral cholangiocarcinoma ○ PET may help identify multiple sites of active inflammatory disease – May help guide biopsy

DIFFERENTIAL DIAGNOSIS

Radiographic Findings

IgG4-Related Sclerosing Disease (IgG4-RD)

• ERCP or transhepatic cholangiography ○ Hilar biliary pseudotumor – Short stricture with dilation of upstream ducts ○ Less diffuse biliary irregularity than seen with primary sclerosing cholangitis (PSC) – Although some cases of IgG4 (autoimmune) cholangitis are indistinguishable from PSC on imaging alone

• Multisystem autoimmune disease • Probably accounts for many cases of inflammatory pseudotumor ○ IgG4-RD was only recently described as a specific entity ○ Was not specifically looked for in earlier reports of inflammatory pseudotumor • Many cases of IgG4 (autoimmune) cholangitis have been reported ○ Some have imaging findings similar to Klatskin tumor and biliary inflammatory pseudotumor

CT Findings • CECT ○ Peripheral mass – Heterogeneous enhancement on arterial and venous phase □ Usually not hypervascular

Liver

TERMINOLOGY

Peripheral Hepatic Mass • Cholangiocarcinoma (peripheral) ○ May be indistinguishable from pseudotumor by imaging alone 803

Liver

Hepatic Inflammatory Pseudotumor

• Hepatocellular carcinoma ○ Large, heterogeneous, hypervascular mass with portal vein invasion ○ Hypodense to surrounding liver on delayed phase CECT (tumor washout) • Hepatic metastases and lymphoma ○ Metastases: Multiple, random distribution ○ Lymphoma: Homogeneous, rarely obstructs ducts – No delayed enhancement of tumor

Hilar Biliary Stricture or Mass • Hilar cholangiocarcinoma ○ Imaging features may be indistinguishable from pseudotumor

PATHOLOGY General Features • Etiology ○ Genetic mutation – Aberrant expression of ALK gene has been identified in > 68% of inflammatory myofibroblastic tumors (IMTs) – IMT masses contain fewer IgG4-positive plasma cells than masses associated with IgG4 sclerosing disease – IMTs do not show obstructive phlebitis – IMT is considered neoplastic counterpart of inflammatory pseudotumor ○ Autoimmune disease (for some cases) – Has been linked in some case to other IgG4-related sclerosing diseases, such as autoimmune pancreatitis and cholangitis – IgG4 sclerosing disease in many organs may cause tumor-like masses with vascular (and ductal) obstruction □ Autoimmune pancreatitis may mimic ductal carcinoma (common cause of unnecessary Whipple resection) □ Similar mass-like lesions are reported in kidney, lungs, retroperitoneum, mediastinum, thyroid □ These masses do not have immunohistochemical evidence of aberrant ALK gene expression □ Obliterative phlebitis is a feature of IgG4-RD, but not inflammatory myofibroblastic tumor

Gross Pathologic & Surgical Features • Hard scirrhous mass with compression and obliteration of bile ducts and blood vessels

Microscopic Features • Bland-appearing proliferation of spindle cells with fibrosis and inflammatory infiltrate of lymphocytes and plasma cells • Obliterative phlebitis and cholangitis ○ Much more common in IgG4-related form of inflammatory pseudotumor • Lymphoplasmacytic infiltration ○ Same histology seen in autoimmune (IgG4) pancreatitis • Bile duct wall thickening, periductal fibrosis similar to primary sclerosing cholangitis ○ Also similar to that described in autoimmune (IgG4) cholangitis

804

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Peripheral hepatic pseudotumor – Vague abdominal pain – Low-grade fever, leukocytosis – Weight loss, fatigue ○ Hilar biliary pseudotumor – Jaundice, leukocytosis – Abnormal liver function tests □ serum bilirubin, alkaline phosphatase – erythrocyte sedimentation rate (ESR)

Treatment • May respond to steroids and other anti-inflammatory medications • Surgical resection is indicated in symptomatic cases with large mass or inability to distinguish from cholangiocarcinoma

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Look for imaging, clinical, and laboratory (serum IgG4 levels) evidence of IgG4-related sclerosing disease ○ Often a multisystem disorder (e.g., autoimmune pancreatitis, cholangitis, pneumonitis, etc.)

SELECTED REFERENCES 1.

Chen CB et al: Hepatic inflammatory pseudotumor mimicking hepatocellular carcinoma. J Chin Med Assoc. 76(5):299-301, 2013 2. Fernandes T et al: Peripheral inflammatory pseudotumor of the liver and extensive thrombosis of the portal venous system in a child. Pediatr Radiol. 43(8):1041-4, 2013 3. Nagarajan S et al: Inflammatory myofibroblastic tumor of the liver in children. J Pediatr Gastroenterol Nutr. 57(3):277-80, 2013 4. Alswat K et al: The spectrum of sclerosing cholangitis and the relevance of IgG4 elevations in routine practice. Am J Gastroenterol. 107(1):56-63, 2012 5. Carruthers MN et al: The latest on IgG4-RD: a rapidly emerging disease. Curr Opin Rheumatol. 24(1):60-9, 2012 6. Beauchamp A et al: Inflammatory myofibroblastic tumor of the liver in an elderly woman following a second liver biopsy: a case report. Bol Asoc Med P R. 103(2):60-4, 2011 7. Dechoux S et al: IgG4-related sclerosing disease: autoimmune pancreatitis (AIP) and IgG4-related cholangitis. Clin Res Hepatol Gastroenterol. 35(10):601, 2011 8. Herek D et al: Education and imaging. Hepatobiliary and pancreatic: inflammatory pseudotumors of the liver. J Gastroenterol Hepatol. 26(7):1217, 2011 9. Kim F et al: IgG4-related tubulointerstitial nephritis and hepatic inflammatory pseudotumor without hypocomplementemia. Intern Med. 50(11):1239-44, 2011 10. Vlachou PA et al: IgG4-related sclerosing disease: autoimmune pancreatitis and extrapancreatic manifestations. Radiographics. 31(5):1379-402, 2011 11. Deng FT et al: Hilar inflammatory pseudotumor mimicking hilar cholangiocarcinoma. Hepatobiliary Pancreat Dis Int. 9(2):219-21, 2010 12. Tublin ME et al: Biliary inflammatory pseudotumor: imaging features in seven patients. AJR Am J Roentgenol. 188(1):W44-8, 2007

Hepatic Inflammatory Pseudotumor Liver

(Left) Axial T1WI in a 55-yearold man with hepatic dysfunction shows a large spherical mass that is generally hypointense with a lower intensity central scar. (Right) Axial T2WI in the same case shows the mass as a bright lesion with an even higher intensity central scar. The findings were considered suggestive of a malignancy, but at biopsy and subsequent resection, this proved to be an inflammatory pseudotumor of the liver.

(Left) Arterial phase CECT in a 48-year-old woman with jaundice shows dilation of intrahepatic ducts and a poorly defined, small mass at the duct bifurcation. (Right) Portal venous phase CT in the same case shows the ductal obstruction and the mass at the confluence of the main right and left ducts.

(Left) Delayed phase CT in the same case shows persistent, increased retention of contrast material within the hilar mass , findings considered very suggestive of a hilar (Klatskin) cholangiocarcinoma. (Right) Thick-slab MRCP in the same case shows biliary obstruction at the bifurcation . While imaging features favored a Klatskin tumor, final surgical pathology proved this was an inflammatory pseudotumor.

805

Liver

Hepatocellular Carcinoma KEY FACTS

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Most frequent primary visceral malignancy in world • Important to detect and stage accurately ○ Small tumors (< 3 cm without vascular invasion) are curable with resection, ablation, transplantation ○ Achievable goal of surveillance program using US, CT, &/or MR (properly performed and interpreted) ○ Use LI-RADS classification system for focal lesions in cirrhotic liver • Key imaging features ○ Heterogeneous hypervascularity on arterial phase (CT or MR) with washout on venous and delayed ○ Presence of a capsule or fat content ○ Evidence of portal or hepatic vein invasion ○ Hypointense lesion on hepatobiliary phase of gadoxetate-enhanced MR ○ Bright lesion on diffusion-weighted MR

• • • •

Regenerative and dysplastic nodules Cholangiocarcinoma (peripheral) Nodular regenerative hyperplasia Hypervascular metastases

CLINICAL ISSUES • Which imaging modality should be used? ○ Sonography – Effective in expert hands in screening thin patients with relatively nonfibrotic livers ○ Triphasic CT or MR (arterial, venous, and delayed phases) is mandatory in more advanced disease – Any focal lesion; fibrotic, nodular liver; strong clinical concern for HCC – MR with gadoxetate enhancement has greater sensitivity and specificity for analyzing nodules

The Liver Imaging Reporting and Data System (LI-RADS) is endorsed by the ACR for categorization of focal nodular lesions found on CT or MR in the cirrhotic liver. It is designed to standardize the interpreting and reporting of findings so that these are more uniform, accurate, and useful to referring physicians.

806

Hepatocellular Carcinoma

Abbreviations • Hepatocellular carcinoma (HCC)

Synonyms • Hepatoma • Primary liver cancer

Definitions • Most common primary malignant liver tumor, usually arising in a cirrhotic liver

IMAGING General Features • Best diagnostic clue ○ Heterogeneous hypervascular mass with "washout" of contrast enhancement and portal vein invasion • Size ○ Small tumors < 2 cm ○ Large tumors > 5 cm – Diffuse: Subcentimeter to few cm lesions throughout liver • Morphology ○ Usually spherical • Key concepts ○ Most frequent primary visceral malignancy in world – Accounts for 80-90% of all primary liver malignancies ○ 2nd most common malignant liver tumor in children after hepatoblastoma ○ Important to detect and stage accurately – Small tumors are curable with resection, ablation, or transplantation – Multiple, large, or those with venous invasion can be palliated with chemoembolization ○ Signs of portal vein invasion by HCC – Expansion of portal vein lumen – Enhancement of tumor within vein – Contiguity of tumor and portal vein

CT Findings • NECT ○ In noncirrhotic liver (usually a symptomatic patient, as with pain or rupture) – Solitary HCC: Large hypodense mass; ± necrosis, fat, calcification – Encapsulated HCC: Well-defined, rounded, hypodense mass □ Dominant hypodense mass with decreased attenuation "satellite" nodules – Multifocal HCC: Multiple hypodense lesions rarely with central necrotic portion ○ In cirrhotic liver (usually detected as part of a surveillance program) – HCC may be hypodense to liver – Regenerative nodules may be hyperdense to liver • CECT ○ Hepatic arterial phase (HAP) scan – Heterogeneous hypervascular enhancement (for moderately and poorly differentiated HCC)

□ Well-differentiated tumor may be hypodense to liver on all phases of enhancement – Wedge-shaped areas of density on HAP: Perfusion abnormality due to portal vein occlusion by tumor thrombus and arterial flow ○ Portal venous phase (PVP) scan – HCC often nearly isodense to surrounding liver ○ Delayed scan: HCC hypodense to surrounding liver – Washout of contrast enhancement is key finding □ Helps to distinguish HCC from regenerative nodules and arterioportal shunts (both common in cirrhosis) ○ Small hypervascular HCC – Early and late arterial phases: Hyperattenuating, more on 2nd or later arterial phase – Later (portal venous and delayed): HCC washes out to become hypodense to liver

Liver

TERMINOLOGY

MR Findings • Variable intensity depending on degree of fatty change, fibrosis, necrosis • T1WI ○ HCC may be hypo-, iso-, or hyperintense to liver ○ Tumors with fat or hemorrhage are hyperintense • T2WI ○ Usually hyperintense to liver – Regenerative nodules are hypointense on T2WI ○ HCC arising within dysplastic nodule – "Nodule within nodule" pattern – HCC appears as small focus of increased signal intensity within decreased signal intensity nodule • T1 C+ (gadolinium) ○ Heterogeneously hyperintense, with washout on portal venous and delayed phase ○ Rapid central washout with residual capsular enhancement = HCC, not arterioportal shunt • Hepatobiliary contrast agent (gadoxetate) ○ Trade names: Eovist or Primovist ○ On 20 minute delayed phase – Normal liver (and some portions of cirrhotic liver) enhance brightly – Most HCCs are seen as hypointense focal masses – Rare for well-differentiated HCC to show delayed persistent enhancement with gadoxetate ○ Increases sensitivity of MR in diagnosing small HCC • Diffusion-weighted MR ○ Restricted diffusion within HCC often detected as bright signal in focal lesion ○ Adds sensitivity and specificity to MR detection of HCC

Ultrasonographic Findings • Grayscale ultrasound ○ Lower sensitivity and specificity than CT or MR in diagnosing HCC – Especially within nodular, fibrotic, cirrhotic liver ○ Mixed echogenicity due to tumor necrosis and hypervascularity ○ Hypoechoic: Due to solid tumor ○ Hyperechoic: Due to fatty metamorphosis – Small hyperechoic HCC can simulate hemangioma ○ Capsule: In encapsulated HCC 807

Liver

Hepatocellular Carcinoma ○

– Thin hypoechoic band • Color Doppler ○ Shows hypervascularity and tumor shunting ○ Small HCC: Indistinguishable from regenerative and dysplastic nodules

-1-antitrypsin deficiency, hereditary hemochromatosis, Wilson disease, tyrosinosis • Genetics ○ HBV DNA integrated into host's genomic DNA in tumor cells

Angiographic Findings

Gross Pathologic & Surgical Features

• Conventional ○ Hypervascular tumor – Marked neovascularity and AV shunting – Large hepatic artery and vascular invasion ○ Threads and streaks sign – Sign of tumor thrombus in portal vein

• Solitary, nodular or multifocal, diffuse, encapsulated • Soft tumor ± necrosis, hemorrhage, calcification, fat, vascular invasion

Microscopic Features • Histologic appearances: Solid (cellular) or acinar • Increased fat and glycogen in cytoplasm

Imaging Recommendations • Best imaging tool ○ In cirrhotic patient, multiphasic CT or MR ○ Triphasic CT or MR (arterial, venous, and delayed phases) – MR with gadoxetate enhancement has greater sensitivity and specificity

Presentation

• Peripheral tumor often obstructs bile ducts • Capsular retraction, volume loss • Delayed enhancement on C+ CT or MR

• Most common signs/symptoms ○ Usually detected in screening/surveillance program in patients with cirrhosis or chronic hepatitis ○ May present with acute pain due to rupture through hepatic capsule • Other signs/symptoms ○ Other symptoms are nonspecific and difficult to distinguish from those due to cirrhosis and portal hypertension • Clinical profile ○ Elderly patient with history of cirrhosis, ascites, weight loss, RUQ pain, and -fetoprotein (AFP) • Lab data: Increased AFP and liver function tests • Diagnosis ○ CT and MR findings are often specific enough to guide therapy without tissue confirmation

Nodular Regenerative Hyperplasia

Demographics

• Focal form, a.k.a. large regenerative nodules • Usually seen in Budd-Chiari syndrome • Multiple masses (1-4 cm) with persistent hyperenhancement on arterial and portal venous phase • Retain gadoxetate on hepatobiliary phase of MR imaging • May have "halo" of nonenhancement around mass or in central scar

• Age ○ Low incidence areas (e.g., USA and Europe) – HCC diagnosed at age 50-60 ○ Endemic areas: 30-45 years old • Gender ○ M:F = 2.5:1 for low-incidence areas ○ M:F = 8:1 for high-incidence areas • Epidemiology ○ 250,000-1,000,000 deaths per year globally – 2nd leading cause of cancer death in men worldwide – In USA, HCC is 7th leading cause of cancer death ○ High incidence: Africa and Asia – Due to endemic HBV and aflatoxins ○ Lower incidence in North and South America, Western Europe, Australia – But increasing due to chronic hepatitis C (drug use and blood transfusions in 1980s) □ Also due to immigrants from areas with endemic viral hepatitis □ Likely also due to prevalence of obesity with nonalcoholic steatohepatitis (NASH) □ NASH may become the leading cause of HCC in USA and Europe ○ Risk factors – Hepatitis B □ Especially in men with high viral loads

DIFFERENTIAL DIAGNOSIS Regenerative and Dysplastic Nodules • Regenerative: Small, multiple, very hypointense on T2WI and GRE • Dysplastic: Hyperintense on T1WI; hypointense on T2WI; usually do not show vascularity, restricted diffusion, or appear as defects on delayed gadoxetate-enhanced MR

Cholangiocarcinoma (Peripheral)

Hypervascular Metastases • • • •

Mimic small nodular or multifocal HCC Metastases to a cirrhotic liver are rare Less likely to invade portal vein Usually due to endocrine primary tumor

PATHOLOGY General Features • Etiology ○ Cirrhosis (60-90%): Due to chronic viral hepatitis (HBV, HCV) or alcoholism – Even patients without cirrhosis usually have chronic liver injury (e.g., by hepatitis B) ○ Nonalcoholic steatohepatitis (NASH) – Increasingly common cause for cirrhosis and HCC ○ Carcinogens – Aflatoxins, siderosis, Thorotrast, androgens 808

CLINICAL ISSUES

Hepatocellular Carcinoma

– –

–

Natural History & Prognosis • Complications ○ Spontaneous rupture and massive hemoperitoneum ○ IVC invasion, possible tumor embolism to lungs ○ Metastases (adrenals and lungs most common) • Prognosis ○ > 90% mortality rate; 17% resectability rate – Appropriate candidates for transplantation have good disease-free survival □ ~ 85% 5-year survival ○ Average survival time 6 months after diagnosis of symptomatic HCC – But greater for HCC discovered in surveillance program – Goal is to diagnose tumors < 3 cm in diameter that are limited to liver □ Properly performed and interpreted CT or MR can accomplish this goal

Treatment • Surgical resection ○ Optimal treatment, but limited by inadequate hepatic reserve in most patients ○ Ideal candidate: Small peripheral tumor without vascular invasion • Radiofrequency ablation ○ Small (generally < 3-4 cm) isolated tumors ○ In patients who are not candidates for surgical resection • Transarterial chemoembolization (TACE) ○ For patients with multifocal unresectable tumor – Often limited due to insufficient hepatic reserve ○ May be used as bridging therapy before transplantation • Radioembolization ○ With yttrium-90Y-tagged microspheres ○ Alternative to TACE • Transplantation ○ For those with small tumor, no vascular invasion or metastases ○ Milan criteria for transplantation – Solitary HCC ≤ 5 cm diameter, or up to 3 HCC nodules, each ≤ 3 cm diameter – No vascular invasion or extrahepatic tumor • Systemic therapy ○ Modest survival benefit with sorafenib (tyrosine kinase inhibitor)

Surveillance for HCC

Liver

–

□ Onset of HCC may precede development of cirrhosis Hepatitis C □ Accounts for ~ 1/3 of cases in USA □ Alone or in combination with alcohol abuse □ Onset of HCC usually decades after HCV infection; after onset of cirrhosis Alcoholic cirrhosis □ HCC develops after cirrhosis "Cryptogenic cirrhosis" □ Probably the end result of NASH □ Increasing cause for HCC Other causes of cirrhosis □ Primary biliary cirrhosis, hemochromatosis, autoimmune hepatitis, etc.

• Goal is to detect early, small HCC at curable stage • Who should be screened? ○ All patients with proven cirrhosis (any etiology) ○ Hepatitis B carriers who also have cirrhosis, or – Are Asian or African American – Have family history of HCC – Have high viral loads • Which imaging modality should be used? ○ Sonography – Usually repeated at ~ 6-month intervals – Effective in expert hands in examining thin patients with relatively nonfibrotic livers ○ Computed tomography or MR – To evaluate any focal lesion > 1 cm detected by US – To evaluate liver that is distorted by fat, fibrosis, nodularity – To evaluate patient considered at high risk for HCC even with normal US – Usually repeated at ~ 12-month intervals as problemsolving test

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Within cirrhotic liver ○ Encapsulated or fat-containing mass is likely HCC ○ Mass with restricted diffusion or no uptake of gadoxetate is likely HCC

Reporting Tips • Use LI-RADS classification system ○ Provides standardized criteria for interpreting findings of CT & MR examinations in patients with chronic liver injury • Accurately report vascular invasion and number and size of lesions

SELECTED REFERENCES 1. 2.

3. 4. 5.

6.

7. 8.

Gaddikeri S et al: Hepatocellular carcinoma in the noncirrhotic liver. AJR Am J Roentgenol. 203(1):W34-47, 2014 Jha RC et al: LI-RADS categorization of benign and likely benign findings in patients at risk of hepatocellular carcinoma: a pictorial atlas. AJR Am J Roentgenol. 203(1):W48-69, 2014 Roth CG et al: Hepatocellular carcinoma and other hepatic malignancies: MR imaging. Radiol Clin North Am. 52(4):683-707, 2014 Gonzalez SA et al: Risk assessment for hepatocellular carcinoma in chronic hepatitis B: scores and surveillance. Int J Clin Pract. 66(1):7-10, 2012 Becker-Weidman DJ et al: Hepatocellular carcinoma lesion characterization: single-institution clinical performance review of multiphase gadoliniumenhanced MR imaging--comparison to prior same-center results after MR systems improvements. Radiology. 261(3):824-33, 2011 Haradome H et al: Additional value of gadoxetic acid-DTPA-enhanced hepatobiliary phase MR imaging in the diagnosis of early-stage hepatocellular carcinoma: comparison with dynamic triple-phase multidetector CT imaging. J Magn Reson Imaging. 34(1):69-78, 2011 Sano K et al: Imaging study of early hepatocellular carcinoma: usefulness of gadoxetic acid-enhanced MR imaging. Radiology. 261(3):834-44, 2011 Starr SP et al: Cirrhosis: diagnosis, management, and prevention. Am Fam Physician. 84(12):1353-9, 2011

809

Liver

Hepatocellular Carcinoma

(Left) Graphic shows a heterogeneous hypervascular mass invading the portal vein . The surrounding liver is cirrhotic with a nodular contour, and there is ascites. Satellite nodules of HCC surround the dominant mass. (Right) Axial CECT in venous phase shows a hypodense mass in a cirrhotic liver invading and occluding the posterior branch of the right portal vein . Nonocclusive thrombus is present within the main portal vein. This HCC was hypervascular on arterial phase CECT.

(Left) Axial venous phase T1WI MR in a 54-year-old man with alcoholic cirrhosis shows a multifocal hypointense mass that directly invades the portal vein and obstructs intrahepatic bile ducts . Note ascites and typical signs of cirrhosis. (Right) Axial T1W MR in the same patient shows a mass in the right adrenal , a metastasis that has a similar appearance to the tumor within the portal vein . While extrahepatic metastases from HCC are uncommon, the adrenals are among the more common sites of these.

(Left) Axial NECT shows a mass with portions that are unusually hypodense due to the presence of fat within the tumor. The fatty elements within the HCC were still evident on portal venous phase CECT (not shown). (Right) Longitudinal ultrasound in the same patient shows an unusually echogenic mass corresponding to the fatty foci within the HCC seen on CT. Macroscopic fat within a mass in a cirrhotic liver is very suggestive of HCC though it is present in only a minority of cases.

810

Hepatocellular Carcinoma Liver

(Left) Multifocal HCC may simulate metastases, as in this case. Axial arterial phase CECT shows multiple hypervascular foci and expansion of the left portal vein by enhancing tumor thrombus. (Right) Axial portal venous phase CECT in the same patient shows washout of contrast from the HCC foci , as well as the portal vein tumor thrombus . The presence of the tumor thrombus is useful in distinguishing HCC from metastases, which rarely invade the portal vein.

(Left) Arterial phase CECT in an 80-year-old man with no known liver disease shows a large mass with a "mosaic" pattern of enhancement and a thin rim or capsule . These are typical features of HCC that arise in a noncirrhotic liver, such as someone with chronic hepatitis B infection. (Right) A catheter angiogram in the same patient shows that the "capsule" is composed of large feeding arteries along the periphery of the mass.

(Left) (A) T2WI shows a focal mass that is slightly hyperintense to background liver. (B) The same lesion is hypervascular on arterial phase C+ T1WI. (Right) In the same patient, on delayed phase T1WI (A) the mass demonstrates contrast washout and a capsule, very typical signs of HCC. Diffusionweighted image (B) shows bright signal representing restricted diffusion, another typical feature of HCC.

811

Liver

Hepatocellular Carcinoma

(Left) Axial T2WI MR in a 66year-old man with chronic hepatitis B shows a moderately hyperintense spherical mass in the hepatic dome, along with 2 smaller cysts. (Right) Fatsuppressed T1WI MR in the same patient shows the mass as hypointense to surrounding liver.

(Left) T1WI GRE in-phase MR in the same patient shows the mass as slightly hypointense to liver. (Right) T1WI GRE opposed-phase MR in the same patient shows signal dropout from the mass , indicating lipid content. The presence of microscopic fat (as in this case) or macroscopic fat is a very suggestive sign of HCC in a mass within a cirrhotic liver.

(Left) Arterial phase contrastenhanced T1WI MR in the same patient shows heterogeneous hypervascularity within the mass , which is essentially diagnostic of HCC in this setting. (Right) Delayed phase contrast-enhanced T1WI MR in the same patient shows washout of contrast from the mass and a suggestion of a capsule , another characteristic sign of HCC.

812

Hepatocellular Carcinoma Liver

(Left) Transverse (A) and longitudinal (B) US images show a spherical mass that is solid, encapsulated, and nearly isoechoic to the background cirrhotic liver. This was interpreted as a solitary HCC. (Right) A delayed phase CECT image on the same patient shows an encapsulated mass in the hepatic dome, in addition to the mass identified at US, which was also seen on CT (not shown).

(Left) Axial CECT (same patient) shows the same mass seen on the sonogram as hypervascular to liver on this arterial phase image. In addition, a similar hypervascular HCC is identified in the posterior right lobe , along with tumor thrombus in the portal vein . (Right) CT in the venous phase (same patient) shows washout from the left lobe HCC and tumor thrombus in the portal vein . These additional findings identified this patient as stage 4 HCC, limiting his therapeutic options.

(Left) CT (A & B) in a man with alcoholism, acute pain and hypotension shows perihepatic bleeding . The source of the bleeding was an ruptured large HCC . The liver is diffusely steatotic. (Right) In this case of known HCC following TACE, axial T1WI MR (A) shows a larger mass that has typical features of a nonviable tumor, being hyperintense on T1WI, while a viable smaller tumor is hypointense on T1WI. On the C+ T1WI (B) the viable lesion enhances , while the nonviable mass does not.

813

Liver

Fibrolamellar Carcinoma KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Fibrolamellar carcinoma (FLC) of liver ○ Uncommon malignant hepatocellular tumor • Also known as fibrolamellar hepatocellular carcinoma (HCC) ○ Distinct clinical, histopathologic, and imaging features differentiate it from conventional HCC

• • • •

IMAGING

• FLC simulates FNH due to presence of central scar in both tumors ○ FLC: Bigger, more heterogeneous mass frequently with calcified central/eccentric scar and features of malignancy (vessel &/or biliary obstruction, nodal invasion, and lung metastases) ○ Scar on T2WI: Hypointense in FLC, hyperintense in FNH • Large, heterogeneous, hypervascular tumor in young adult

• Heterogeneously enhancing, large, lobulated mass with hypointense central scar and radial septa ○ Calcification and necrosis are common (> 50%) ○ Nodal metastases (> 50%) ○ Vary from 5-20 cm (mean: 13 cm) ○ "Satellite" nodules are often present • Slow-growing tumor that usually arises in normal (noncirrhotic) liver • Better prognosis than conventional HCC but still locally invasive and frequently metastatic

(Left) Axial graphic shows a large, heterogeneous, hypervascular mass with a central scar and porta hepatis lymphadenopathy . (Right) Axial CECT in a 15-year-old boy shows a large, heterogeneous, hypervascular mass with a large, calcified central scar and cardiophrenic lymphadenopathy . In a young person, these findings are essentially diagnostic of fibrolamellar carcinoma (FLC)

(Left) Axial CECT of a 22-yearold man with abdominal discomfort and a palpable mass shows a large, heterogeneous, lobulated mass with a large central scar containing foci of calcification . Scar calcification is very rare in focal nodular hyperplasia (FNH), by comparison. (Right) Gross pathology of the same patient's resected tumor shows a well-demarcated, lobulated, heterogeneous tumor with bile staining and central or eccentric fibrous scars , typical features of FLC.

814

Focal nodular hyperplasia (FNH) Conventional HCC Hepatic cavernous hemangioma Peripheral cholangiocarcinoma

DIAGNOSTIC CHECKLIST

Fibrolamellar Carcinoma

Abbreviations • Fibrolamellar carcinoma (FLC) of liver

Synonyms • Fibrolamellar hepatocellular carcinoma

Definitions • Uncommon malignant hepatocellular tumor ○ Distinct clinical, histopathologic, and imaging features differentiate it from conventional hepatocellular carcinoma (HCC)

IMAGING General Features • Best diagnostic clue ○ Heterogeneously enhancing, large, lobulated mass with hypointense central scar and radial septa • Location ○ Intrahepatic (80%) ○ Pedunculated (20%) • Size ○ 5-20 cm (mean: 13 cm) • Key concepts ○ Slow-growing tumor that usually arises in normal (noncirrhotic) liver – May occur with underlying cirrhosis (< 5% of cases) ○ "Satellite" nodules are often present ○ Characteristic microscopic pattern – Eosinophilic malignant hepatocytes containing prominent nuclei ○ Absence of pathologic markers (e.g., inclusions of fetoprotein bodies) that are present in conventional HCC ○ Better prognosis than conventional HCC but still locally invasive and frequently metastatic

CT Findings • NECT ○ Mass – Well-defined contour – Hypoattenuating and heterogeneous ○ Central scar and septa: Markedly hypodense ○ Calcification and necrosis are common (> 50%) ○ Hemorrhage is rarely seen • CECT ○ Arterial phase – Mass: Heterogeneous and hyperattenuating (80%) ○ Portal phase – Mass: Iso-/hypoattenuating ○ Delayed phase (10 min) – Mass: Isodense – Scar and septa: Hyperdense ○ Malignant features – Biliary and vessel invasion – Nodal metastases (> 50%) □ Porta hepatis and cardiophrenic nodes – Lung metastases

MR Findings

○ Mass: Heterogeneous and slightly hypointense ○ Scar and septa: Hypointense • T2WI ○ Mass: Heterogeneous and hyperintense ○ Scar and septa: Hypointense • T1WI C+ ○ Arterial and portal phases – Intense heterogeneous enhancement of mass, not scar ○ Delayed phase – Mass: More homogeneous enhancement – Scar and septa: Delayed partial enhancement

Liver

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Mass – Large, solitary, well defined, and lobulated – Variable echotexture ○ Central scar: Hyperechoic

Imaging Recommendations • Multiphasic and multiplanar CT or MR

DIFFERENTIAL DIAGNOSIS Focal Nodular Hyperplasia (FNH) • Marked homogeneous enhancement on arterial phase CT or MR • Scar: Hyperintense on T2WI • Nonencapsulated and no calcification • Homogeneous uptake + delayed retention hepatobiliary MR agents (gadoxetate) ○ Most specific imaging feature of FNH • Microscopic pattern ○ Normal hepatocytes; disorganized bile ductules

Conventional HCC • Cirrhosis or chronic hepatic injury in > 90% • Intratumoral hemorrhage, necrosis, calcification, and fat (more common) • Vascular, nodal, and visceral invasion common • May be multifocal • Conventional HCC in noncirrhotic liver mimics FLC

Hepatic Cavernous Hemangioma • Large hemangioma (> 5 cm) ○ Heterogeneous hypodense mass ○ Central decreased attenuation (scar), rarely with calcification ○ Arterial phase: Peripheral nodular or globular enhancement ○ Venous and delayed phases – Incomplete centripetal filling of lesion – No enhancement of scar • Typical hemangioma: Well-circumscribed spherical to ovoid mass isodense to blood on both NECT and CECT

Peripheral Cholangiocarcinoma • Peripheral hypodense solitary mass or "satellite" lesions • Bile duct dilation upstream from mass • No central scar but extensive fibrosis

• T1WI 815

Liver

Fibrolamellar Carcinoma

• Early rim enhancement with progressive, central, and persistent patchy enhancement • Often causes hepatic volume loss and capsular retraction

PATHOLOGY General Features • Etiology ○ No specific risk factors ○ Usually no underlying cirrhosis or liver disease – Hepatitis and cirrhosis may be present (< 5%)

Staging, Grading, & Classification • When aggressive, staging corresponds to that of conventional HCC

Gross Pathologic & Surgical Features • Large, single, well-demarcated, lobulated, nonencapsulated mass • Cut section: Tan, brown, or brownish green with streaks of fibrous tissue • Infiltrating fibrous septa; central scar (45-60%) • Rarely encapsulated • Solitary mass (80-90%) • Peripheral "satellite" lesions (10-15%) • Intrahepatic (80%); pedunculated (20%) • Size: Average is 13 cm; most vary from 5-20 cm

Natural History & Prognosis • Resectability rate 48% • Median 5-year survival for resectable FLC is 50-75% ○ Falls to 0% for unresectable tumor • FLC is frequently recurrent • Better prognosis compared to conventional HCC

Treatment • Localized tumor ○ Surgical resection of hepatic mass and regional nodes ○ May resect isolated lung metastases • Inoperable cases: Chemotherapy

DIAGNOSTIC CHECKLIST

Microscopic Features

Consider

• Large, eosinophilic, polygonal cells ○ Arranged in sheets/cords/trabeculae ○ Separated by parallel sheets or septa of fibrous tissue (i.e., lamellae) • Large nuclei with prominent nucleoli • Granular-appearing cytoplasm

• Differentiate FLC from FNH and conventional HCC • FLC simulates FNH due to presence of central scar in both tumors

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pain, hepatomegaly, palpable epigastric mass, cachexia ○ Occasionally jaundice when invasion of biliary tract occurs ○ Symptoms – Usually present for 3-12 months before diagnosis ○ Rarely presents with – Metastatic disease, fever, gynecomastia – Venous thrombosis (hepatic, portal, and IVC) • Clinical profile ○ Healthy young adult with large liver mass ○ Presenting symptoms of abdominal discomfort, malaise, weight loss ○ May have gynecomastia or other estrogenic effects • Laboratory data ○ Usually -fetoprotein levels are normal – In 10% of cases, mild increase in levels (< 200 ng/μL) – Rarely, marked increase in levels (10,000 ng/μL) □ Similar to conventional HCC • Diagnosis: Biopsy and histology

Demographics • Age 816

○ Adolescents/young adults – Age range of 5-69 years (mean: 23 years) ○ Most patients present in 2nd-3rd decade of life • Gender ○ No gender predominance • Epidemiology ○ Increased prevalence in USA, especially in Caucasians – Less common in Europe – Rare in Asia ○ FLC accounts for 1-9% of all cases of HCC ○ Represents 35% of HCC in patients < 50 years of age

Image Interpretation Pearls • FLC: Bigger, more heterogeneous mass, frequently with calcified central/eccentric scar and features of malignancy (vessel/biliary obstruction, nodal invasion, and lung metastases) • Scar on T2WI: Hypointense (FLC), hyperintense (FNH) • Large, heterogeneous, hypervascular tumor in young adult

SELECTED REFERENCES 1. 2. 3.

4. 5.

6. 7.

8. 9.

Ganeshan D et al: Imaging features of fibrolamellar hepatocellular carcinoma. AJR Am J Roentgenol. 202(3):544-52, 2014 Roth CG et al: Hepatocellular carcinoma and other hepatic malignancies: MR imaging. Radiol Clin North Am. 52(4):683-707, 2014 Mayo SC et al: Treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma: a national perspective. J Am Coll Surg. 218(2):196205, 2014 Taylor SL et al: Hepatobiliary pathology. Curr Opin Gastroenterol. 27(3):24855, 2011 Ward SC et al: Fibrolamellar carcinoma: a review with focus on genetics and comparison to other malignant primary liver tumors. Semin Liver Dis. 31(1):61-70, 2011 Smith MT et al: Best cases from the AFIP: fibrolamellar hepatocellular carcinoma. Radiographics. 28(2):609-13, 2008 Ichikawa T et al: Fibrolamellar hepatocellular carcinoma: pre- and posttherapy evaluation with CT and MR imaging. Radiology. 217(1):145-51, 2000 Ichikawa T et al: Fibrolamellar hepatocellular carcinoma: imaging and pathologic findings in 31 recent cases. Radiology. 213(2):352-61, 1999 McLarney JK et al: Fibrolamellar carcinoma of the liver: radiologic-pathologic correlation. Radiographics. 19(2):453-71, 1999

Fibrolamellar Carcinoma Liver

(Left) The fibrolamellar variant of hepatocellular carcinoma typically has a lobular growth pattern and central scar . Also note the absence of cirrhosis in the background liver. (Courtesy J. Misdraji, MD.) (Right) Lowpower view of fibrolamellar carcinoma shows cords of neoplastic hepatocytes separated by parallel arrays of collagenous stroma . (Courtesy J. Misdraji, MD.)

(Left) Axial CECT of a 21-yearold woman with a palpable epigastric mass shows a brightly enhancing mass within the left lobe of the liver. The mass is slightly heterogeneous and has a central scar and several small calcifications . Heterogeneity and calcifications favor fibrolamellar carcinoma over FNH. (Right) In the same patient, again noted are heterogeneity and small calcifications within the mass which was resected and proved to be fibrolamellar carcinoma.

(Left) T2WI MR in a 25-yearold man with early satiety and weight loss shows a large, heterogeneous, bilobed mass that is hyperintense to the liver. Note the hypointense central scar . (Right) Axial arterial phase T1 C+ MR in the same patient shows welldemarcated, lobulated, heterogeneous, and relatively vascular, dominant and satellite masses . The fibrous scars show little enhancement on this phase of imaging but would often demonstrate delayed persistent enhancement in fibrolamellar carcinoma.

817

Liver

Fibrolamellar Carcinoma

(Left) Axial NECT of a 17-yearold boy with a palpable epigastric mass shows a large mass with foci of calcification . Such large foci of calcification are essentially never seen in FNH. (Right) Arterial phase CECT of the same patient shows heterogeneous hypervascularity of the mass with a large feeding artery .

(Left) Axial arterial phase CECT in the same patient shows heterogeneous hypervascularity of the mass and an enhancing tumor thrombus distending the portal vein . Regional nodal metastases show similar hypervascularity. Lung metastases were also seen. (Right) Venous phase CECT of the same patient shows persistent heterogeneity of the tumor and some washout of contrast from the portal vein tumor thrombus and metastatic nodes . The foci of calcification are again noted .

(Left) T2WI MR in a 20-yearold woman with early satiety and weight loss shows a large, heterogeneous mass replacing the left lobe of the liver. Note the hypointense central scar . (Right) Axial arterial phase T1 C+ MR in the same patient shows that the mass remains heterogeneous. This mass was resected, along with local lymph node metastases, because of the patient's young age and symptoms, the lack of alternative therapy, and evidence of improved survival with tumor debulking.

818

Fibrolamellar Carcinoma Liver

(Left) Arterial phase axial CECT in a 35-year-old man with palpable epigastric mass shows a large, lobulated mass with tumor vessels that are enlarged and irregularly branching. (Right) More caudal section in a CECT of the same patient shows the heterogeneous hypervascularity of the mass , along with central lower density. Note the enlarged feeding artery .

(Left) Venous phase imaging of the same patient shows the lobulated, encapsulated mass with persistent heterogeneity, helping to differentiate this from FNH. (Right) In the same patient, a more caudal venous phase section shows the heterogeneity of the mass .

(Left) Delayed phase CECT of the same patient shows foci of the tumor that retain contrast and become hyperdense to the liver, representing fibrous stroma, a characteristic feature of fibrolamellar HCC. (Right) Coronal reformatted CT of the same patient shows the mass with features (large, hypervascular, heterogeneous, with a large central scar) essentially diagnostic of fibrolamellar HCC when seen in a young person with no clinical or imaging evidence of cirrhosis or chronic liver disease.

819

Liver

Peripheral (Intrahepatic) Cholangiocarcinoma KEY FACTS

TERMINOLOGY • Tumor arising from intrahepatic bile ducts

IMAGING • Infiltrative hepatic mass with capsular retraction and delayed persistent enhancement (CECT and MR) • Peripheral CCA is usually mass-forming tumor ○ Most common type of CCA ○ Well circumscribed, large, with lobulated margins ○ Multicentricity, especially around main tumor • Periductal-infiltrating CCA ○ Grows along bile ducts and is elongated, spiculated, or branch-like • Progressive, gradual, and concentric filling (centripetal) on delayed phase images ○ Usually not isodense to vessels (unlike hemangioma) • Substantial delayed enhancement (i.e., greater than that of liver parenchyma) is common (74%) ○ Attributed to fibrous stroma in CCA

(Left) Intrahepatic cholangiocarcinomas generally arise in noncirrhotic livers. This gross photograph shows a white-tan, firm, and distinct mass in a background of noncirrhotic liver. (Courtesy M. Yeh, MD, PhD.) (Right) Desmoplastic stroma is a common finding in intrahepatic cholangiocarcinoma. (Courtesy M. Yeh, MD, PhD.)

(Left) Axial CECT of a 46-yearold woman with jaundice shows the portal vein and bile ducts encased and obstructed by the tumor , accounting for the altered perfusion of the right hepatic lobe. Hepatic veins were encased as well, resulting in collateral blood vessels seen within the right lobe . (Right) Axial 10-minute delayed CECT in the same patient shows heterogeneous, persistent enhancement of the tumor , a feature of cholangiocarcinoma (and other tumors with fibrous stroma).

820

• ± capsular retraction (frequent), with parenchymal atrophy of liver segments peripheral to tumor • Bile ducts will be dilated upstream from tumor ○ Duct lining may be thickened and enhanced ○ Rare with other types of hepatic tumors

TOP DIFFERENTIAL DIAGNOSES • Hepatic metastases and lymphoma • Hepatocellular carcinoma • Focal confluent fibrosis

PATHOLOGY • Based on growth characteristics ○ Mass forming (exophytic/nodular); most common form ○ Periductal infiltrating (sclerosing) ○ Intraductal growing (polypoid/papillary)

CLINICAL ISSUES • Only minority of cholangiocarcinomas are peripheral type • Large size at presentation contributes to poor prognosis

Peripheral (Intrahepatic) Cholangiocarcinoma

Abbreviations • Cholangiocarcinoma (CCA)

Synonyms • Cholangiocellular carcinoma, intrahepatic cholangiocarcinoma

Definitions • CCA: Adenocarcinoma arising from bile duct epithelium (cholangiocytes) • Peripheral CCA: Tumor arising from intrahepatic bile ducts

IMAGING General Features • Best diagnostic clue ○ Infiltrative hepatic mass with capsular retraction and delayed persistent enhancement (CECT and MR) • Location ○ Originates from interlobular bile ducts (i.e., bile ducts distal to 2nd order branches) • Morphology ○ Peripheral CCA is usually a mass-forming tumor – Often has "satellite" nodules • Key concepts ○ Mass-forming CCA: Well circumscribed, large, with lobulated margins – Multicentricity, especially around main tumor ○ Periductal-infiltrating CCA: Grows along bile ducts and is elongated, spiculated, or branch-like ○ Intraductal-growing CCA: Small, sessile, or polypoid – Often spreading superficially along mucosal surface and resulting in multiple tumors (papillomatosis) along various segments of bile ducts

CT Findings • NECT ○ Well-defined, predominantly homogeneous, hypodense mass – Lobular margins – Hypodense satellite nodules (65% of CCAs) – Punctate, stippled, chunky calcifications (18% of CCAs) • CECT ○ Mass-forming PCC – Thin or thick rim-like enhancement frequently seen around periphery of tumor on arterial phase images – Progressive, gradual, and concentric filling (centripetal) on delayed phase images □ Usually not isodense to vessels (unlike hemangioma) – Substantial delayed enhancement (i.e., > that of liver parenchyma) is common (74%) □ Attributed to fibrous stroma in CCA – Homogeneous or heterogeneous hyperattenuating enhancement □ Entire mass may be enhanced only on delayedphase images □ May be only evidence of tumor – ± capsular retraction (frequent), with parenchymal atrophy of liver segments peripheral to tumor

○ Bile ducts will be dilated upstream from tumor – May not be evident in very peripheral CCA – Duct lining may be thickened and enhanced □ Rare for hepatic metastases or other hepatic primary tumors

Liver

TERMINOLOGY

MR Findings • T1WI ○ Heterogeneous hypointense mass • T2WI ○ Hyperintense periphery (cellular tumor) + large central hypointensity (fibrosis) ○ Hyperintense foci in center may represent necrosis, mucin • T1WI C+ ○ Central hypointense areas exhibit homogeneous, heterogeneous, or no enhancement – Regions of fibrosis display enhancement (delayed) while those of coagulative necrosis and mucin show no enhancement ○ Dynamic MR: Minimal or moderate rim enhancement and progressive and concentric filling with contrast material – Intratumoral fibrous stroma displays marked or prolonged enhancement on delayed phase scans – Some cases of PCC exhibiting little fibrosis may show early enhancement on dynamic studies • MRA ○ Displacement or encasement of adjacent vessels

Ultrasonographic Findings • Grayscale ultrasound ○ Mass-forming PCC: Homogeneous or heterogeneous mass with irregular borders and "satellite" nodules – Hyperechoic (75%); iso- &/or hypoechoic (14%) mass ○ Intrahepatic bile ducts of involved hepatic segment may contain calculi or intraductal mass (echogenic): Mucin is echo free

Nuclear Medicine Findings • Cold lesion on sulfur colloid scans • May show uptake on gallium scan

Other Modality Findings • ERCP/percutaneous transhepatic cholangiography ○ Periductal-infiltrating CCA: Lumen of bile duct may be completely obstructed or string-like, severely narrowed bile duct may be seen ○ Intraductal CCA: Biliary tree is dilated (partial obstruction) diffusely, segmentally, or aneurysmally

Imaging Recommendations • Best imaging tool ○ Multiphasic CT or MR to include delayed images • Protocol advice ○ Delayed contrast-enhanced images, obtained 5-20 minutes after contrast injection

DIFFERENTIAL DIAGNOSIS Hepatic Metastases and Lymphoma • Hepatic colorectal metastases 821

Liver

Peripheral (Intrahepatic) Cholangiocarcinoma ○ Metastatic adenocarcinoma histologically similar to PCC, can mimic mass-forming PCC on imaging • Usually less capsular retraction and biliary obstruction with metastases

Hepatocellular Carcinoma (HCC)

Demographics

• Hypervascular on arterial phase, washout on portal venous and delayed phase CT • "Satellite" lesions, venous invasion, and regional lymphadenopathy are common ○ Obstruction of intrahepatic bile ducts is uncommon with HCC

• Age ○ 50-60 years, rarely occurring < 40 years • Gender ○ No gender bias • Epidemiology ○ 8-13% of cholangiocarcinomas are peripheral type ○ Comprises 10-20% of primary liver malignancies

Fibrolamellar HCC

Natural History & Prognosis

• • • •

• Tumoral spread ○ Local extension along duct ○ Local infiltration of liver substance ○ Metastases to regional lymph nodes, peritoneum • Vascular or lymphatic invasion • Perineural invasion • Prognosis: Poor; < 20% resectable; 30% 5-year survival

Large, lobulated, heterogeneous mass with central scar Delayed partial enhancement of fibrous scar and septa Calcification (scar), lymphadenopathy are common Usually occurs in adolescents and young adults

Focal Confluent Fibrosis • Wedge-shaped zone of fibrosis often seen in advanced cirrhotic liver • Also associated with capsular retraction, but without biliary obstruction

PATHOLOGY General Features • Associated abnormalities ○ Associated with several etiological factors: Primary sclerosing cholangitis, bile stasis, recurrent pyogenic cholangitis, clonorchiasis, choledochal cyst

Staging, Grading, & Classification • Based on growth characteristics ○ Mass forming (exophytic/nodular) ○ Periductal infiltrating (sclerosing) ○ Intraductal growing (polypoid/papillary)

Gross Pathologic & Surgical Features • Large, firm, white tumor with dense fibrosis, irregular margins, and capsular retraction

Microscopic Features • 90% are adenocarcinomas (well to moderately differentiated) • Tendency to spread between hepatocyte plates, along duct walls, and adjacent to nerves • Mucin production + desmoplastic, fibrous stroma are often abundant • Most mass-forming PCCs are poorly differentiated; most periductal infiltrating are well differentiated; most intraductal are papillary adenocarcinomas

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain (84%), weight loss (77%), painless jaundice (28%), palpable mass (18%), fatigue ○ Presents as large mass because tumor does not cause clinical symptoms in its early stages • Clinical profile ○ Lab data: serum level of CA19-9 822

– Moderate anemia, leukocytosis, mild AST and ALT, carcinoembryonic antigen ○ Diagnosis: Suggested by imaging, confirmed by biopsy

Treatment • • • •

Surgical resection remains primary treatment Palliative: Biliary catheter drainage, biliary stenting Adjuvant: Radiation and chemotherapy Liver transplantation (not considered appropriate in most cases, high recurrence)

DIAGNOSTIC CHECKLIST Consider • Hepatocellular-cholangiocarcinoma should be considered when hepatic tumor has features of both HCC and CCA • Delayed tumoral contrast enhancement is typical but not specific feature of peripheral CCA ○ Can be seen in other adenocarcinoma metastases and in confluent fibrosis

Image Interpretation Pearls • In suspected cholangiocarcinoma (e.g., history of primary sclerosing cholangitis, or mass with capsular retraction, biliary obstruction) obtain delayed enhanced scans

SELECTED REFERENCES 1.

2. 3.

4.

Apisarnthanarak P et al: The CT appearances for differentiating of peripheral, mass-forming cholangiocarcinoma and liver meatastases from colorectal adenocarcinoma. J Med Assoc Thai. 97(4):415-22, 2014 Roth CG et al: Hepatocellular carcinoma and other hepatic malignancies: MR imaging. Radiol Clin North Am. 52(4):683-707, 2014 Li YY et al: Clinicopathological characteristics of intrahepatic cholangiocarcinoma in patients with cirrhosis. Hepatogastroenterology. 58(110-111):1787-90, 2011 Yamamoto M et al: Surgical outcomes of intrahepatic cholangiocarcinoma. Surg Today. 41(7):896-902, 2011

Peripheral (Intrahepatic) Cholangiocarcinoma Liver

(Left) Axial CECT in arterial phase of a 55-year-old woman with jaundice shows multifocal masses with continuous peripheral ring enhancement . (Right) The portal venous phase in the same patient shows little enhancement of the tumors . The intrahepatic bile ducts are dilated , and the left lobe of the liver is atrophic. Parenchymal atrophy of liver segments affected by peripheral cholangiocarcinoma is common and may be evident as lobar atrophy or capsular retraction.

(Left) Axial T1WI C+ MR in hepatic parenchymal phase shows a large but subtle, heterogeneous mass . Capsular retraction is also noted. This tumor showed persistent enhancement on 10-minute delayed images. (Right) Axial T2WI MR shows mild hyperintensity within a hepatic mass . Dilated intrahepatic ducts are noted upstream from the mass. This is a typical feature of cholangiocarcinoma but may be seen with other tumors.

(Left) Axial CT in the arterial phase shows a large mass with heterogeneous minimal enhancement. Hepatic capsular retraction is a prominent feature of this cholangiocarcinoma. (Right) Axial CT of the same patient shows heterogeneous enhancement on this portal venous phase image. Several "satellite" lesions were present (not shown). The intrahepatic bile ducts are dilated , and there is marked retraction of the liver capsule .

823

Liver

Peripheral (Intrahepatic) Cholangiocarcinoma

(Left) In an 80-year-old man with jaundice, axial CECT in the portal venous phase of enhancement shows a large mass filling much of the right lobe of the liver. The mass obstructs central bile ducts, causing dilation of the peripheral intrahepatic ducts . (Right) In the same patient, the mass encases the portal vein . The delayed set of images (not shown) showed some persistent enhancement in some parts of the tumor and no washout.

(Left) Coronal reformatted CT of the same patient shows the mass with dilation of intrahepatic bile ducts . The CT findings are typical, but not diagnostic, of cholangiocarcinoma. (Right) Coronal reformatted CT image of the same patient shows additional "satellite" tumor nodules , a common feature of intrahepatic cholangiocarcinoma. The term "peripheral" cholangiocarcinoma seems to be a misnomer in cases such as this, but it implies that the tumor arose from intrahepatic bile ducts.

(Left) Axial T2WI FS MR of a 79-year-old woman with recurrent pyogenic cholangitis shows massive dilation of intrahepatic bile ducts with stones and pus within the dependent ducts . Marked ductal dilation plus lobar atrophy of the left lobe are caused by an obstructing mass . (Right) Axial contrastenhanced T1WI MR section of the same patient shows the heterogeneously enhancing mass and the intrahepatic ductal dilation. Cholangiocarcinoma was confirmed at left hepatic resection.

824

Peripheral (Intrahepatic) Cholangiocarcinoma Liver

(Left) Axial NECT of a 67-yearold woman shows a homogeneous hypodense mass with porta hepatic lymphadenopathy . (Right) Axial CECT image of the same patient shows heterogeneous enhancement of the mass, but not as having the nodular, peripheral pattern, isodense with blood vessels, which would have been characteristic of hemangioma.

(Left) CECT image of the same patient shows heterogeneous enhancement of the mass. The enlarged nodes have the same enhancement pattern as the intrahepatic cholangiocarcinoma, indicating nodal metastases. (Right) Axial CECT in delayed phase of the same patient shows foci of hyperdense persistent enhancement , but the lesion does not fill in from the periphery as would be expected of a hemangioma.

(Left) Axial CECT in portal venous phase shows a heterogeneous infiltrative mass with intrahepatic biliary obstruction and volume loss with capsular retraction . (Right) Axial CECT in the delayed phase of the same patient shows increased and persistent enhancement of the tumor due to its fibrous stroma. Other tumor foci have the "target" pattern of enhancement of other types of adenocarcinomas.

825

Liver

Epithelioid Hemangioendothelioma KEY FACTS

IMAGING

PATHOLOGY

• Coalescent peripheral hepatic nodules with "target" appearance and capsular retraction • Target-like enhancement pattern of tumor ○ Enhancing (hyperemic) peripheral inner rim (increased vascularity) ○ Nonenhancing peripheral outer rim or "halo" (avascular rim) ○ Delayed or nonenhancing central part of tumor (myxoid and hyalinized stroma) • Imaging protocol: Multiphasic CT or MR • Spectrum of growth in lesions may be seen: Nodular form (more common); diffuse or extensive form (very rare)

• Slowly progressing, low-grade, malignant vascular tumor of liver ○ Most patients survive 5-10 years after diagnosis • Must not be confused with infantile hemangioendothelioma ○ Benign primary vascular liver tumor ○ Resolves spontaneously in many cases

TOP DIFFERENTIAL DIAGNOSES • • • •

Peripheral cholangiocarcinoma Treated malignancy Focal confluent fibrosis Hemangioma (especially in cirrhotic liver)

(Left) Axial CECT shows multiple peripheral, hypovascular lesions with a "target" appearance (central lucency), typical CT findings of epithelioid hemangioendothelioma (EHE). The subcapsular lesions are associated with retraction of the overlying liver capsule . (Right) CT of the same patient shows more of the multicentric "target" lesions typical of EHE, mostly in a peripheral location within the liver.

(Left) Gross pathology of the same liver after explantation shows the "target" appearance of the lesions, with necrosis and white fibrous tissue in the center of the lesions, as well as a peripheral rim of compressed parenchyma and hyperemic tumor. (Right) Central portion of EHE typically is hypocellular with loosely arranged spindle cells in a fibromyxoid or sclerotic stroma. The findings can simulate a scar or sclerosed hemangioma. (Courtesy S. Kakar, MD.)

826

DIAGNOSTIC CHECKLIST • Usually located at periphery with extension to capsule • Typical capsular retraction of peripheral tumor (due to fibrosis and ischemia) ○ Rule out other hepatic lesions that typically cause capsular retraction • "Target" appearance on CECT or MR • Differentiated from other lesions by tumor cells staining positive for factor VIII-related antigen

Epithelioid Hemangioendothelioma

Abbreviations • Epithelioid hemangioendothelioma (EHE)

Definitions • Primary malignant tumor of liver arising from vascular elements of mesenchymal tissue

IMAGING General Features • Best diagnostic clue ○ Coalescent peripheral hepatic nodules with target-like appearance and capsular retraction • Location ○ Liver – Periphery (> 75%) with extension to capsule ○ Locations other than liver – Soft tissues, bone, and lung • Size ○ Varies from small tumor nodules to large confluent masses • Key concepts ○ Rare primary malignant (low-grade) vascular tumor of liver in adults ○ Other primary malignant vascular tumors of liver – Angiosarcoma (2% of all primary malignant liver tumors) – Kaposi sarcoma: Metastatic vascular tumor in AIDS and transplant recipients ○ All hepatic malignant vascular tumors – Share histologic characteristics – Grow around and into vessels – Tend to be multifocal ○ Clinical course – Less aggressive than angiosarcomas or hepatocellular carcinoma, but still fatal in most cases – Variable and unpredictable – Metastatic in 40% of cases (spleen, mesentery, lymph nodes, lung, bone)

• CECT ○ Target-like enhancement pattern of tumor – Delayed or nonenhancing central part of tumor (myxoid and hyalinized stroma) – Enhancing (hyperemic) peripheral inner rim (increased vascularity) – Nonenhancing peripheral outer rim or "halo" (avascular rim)

MR Findings • T1WI ○ Lesions are hypointense centrally ○ Peripheral, thin, hypointense rim • T2WI ○ Hyperintense centrally ○ Peripheral, thin, hypointense rim • T1WI C+ ○ "Target" pattern: 3 concentric layers of alternating signal intensity (analogous to CECT appearance) – Center: Hypointense – Periphery: Thick, enhancing, inner rim and thin, nonenhancing, outer rim

Ultrasonographic Findings • Grayscale ultrasound ○ Tumor nodules show varied echogenicity pattern – Predominantly hypoechoic – Hyper-/isoechoic lesions may have peripheral hypoechoic rims

Angiographic Findings • Conventional ○ Hypervascular, hypovascular, or avascular lesions – Based on degree of sclerosis and hyalinization ○ Invasion or occlusion of intrahepatic portal and hepatic veins

Imaging Recommendations • Best imaging tool ○ Multiphasic CT or MR • Protocol advice ○ Arterial, venous, delayed phase imaging

CT Findings • Spectrum of growth in lesions may be seen ○ Nodular form (more common) – Multiple liver nodules coalesce to form large, confluent masses ○ Diffuse or extensive form (very rare) • Usually located at periphery with extension to capsule • Capsular retraction (due to tumor fibrosis and ischemia) or flattening; segmental volume loss • Occasional calcification within tumor • Compensatory hypertrophy ○ Uninvolved liver (usually left lobe) • May have extrahepatic metastases and ascites • NECT ○ Tumor nodules – Foci of homogeneous decreased attenuation (due to myxoid stroma) compared to normal liver parenchyma ○ Conspicuity and extent of lesions – CECT superior to NECT

Liver

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Peripheral Cholangiocarcinoma • Heterogeneous mass with capsular retraction • "Satellite" lesions may be seen ○ Usually not as many as with EHE • Intrahepatic bile duct dilatation

Treated Malignancy • • • • •

e.g., hepatocellular carcinoma or metastases Capsular retraction Heterogeneous enhancement pattern History of ablation or chemotherapy for liver tumor Treated metastatic nodules may show ○ Cystic or necrotic changes ○ Debris, mural nodularity ○ Thick septa and wall enhancement

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Liver

Epithelioid Hemangioendothelioma

Focal Confluent Fibrosis • • • • • •

Common in advanced cirrhosis NECT: Areas of lower attenuation than adjacent liver CECT: Isoattenuating or minimally hypo-/hyperattenuating MR: Hypointense on T1WI; hyperintense on T2WI T1 C+: Isointense or delayed enhancement Associated volume loss seen ○ Capsular retraction adjacent to lesion ○ Segmental or lobar shrinkage • Usually wedge-shaped lesions radiating from porta affecting anterior and medial segments

Hemangioma (Especially in Cirrhotic Liver) • Capsular retraction seen in large lesion with scar; hyalinization • Decrease in size over time as cirrhosis progresses • Rest of liver shows cirrhotic changes

PATHOLOGY General Features • Etiology ○ Exact etiology unknown – Possibly associated with oral contraceptives or exposure to vinyl chloride • Slowly progressing, low-grade, malignant vascular tumor of liver ○ Histology – Composed of epithelioid-appearing endothelial cells ○ Abundant matrix of myxoid and fibrous stroma ○ Positive factor VIII-associated antigen staining ○ Malignant cells infiltrate into hepatic sinusoids and compress surrounding hepatocytes ○ May invade hepatic and portal veins ○ Infarction of tumor and central fibrosis • Must not be confused with infantile hemangioendothelioma ○ Histology – Benign primary vascular liver tumor ○ Seen in infants and young children ○ Resolves spontaneously in many cases

Gross Pathologic & Surgical Features • Multiple solid nodules ○ Tan, white, firm, varied size ○ Nodules coalesce more peripherally • Tumor nodules with hyperemic rim • Lesions close to capsule cause retraction

– Due to hepatic vein invasion • Laboratory data ○ Liver enzymes mildly increased ○ -fetoprotein and CEA levels normal • Diagnosis ○ Tumor cells stain positive for factor VIII-related antigen

Demographics • Age ○ 25-58 years (average: 45 years) • Gender ○ M 90% in women

DIAGNOSTIC CHECKLIST • Large, well-defined, homogeneous or heterogeneous, complex cystic mass with septations and nodularity ○ Almost always solitary ○ Enhancing mural nodules suggest malignancy • May mimic hemorrhagic or infected hepatic cyst

Biliary Cystadenocarcinoma

Synonyms • Bile duct cystadenocarcinoma, hepatobiliary cystadenoma

Definitions • Rare, malignant or premalignant, unilocular or multilocular, cystic tumor ○ May arise from intrahepatic bile ducts (IHBDs) within liver (common site) ○ Very rarely from extrahepatic biliary tree or gallbladder

IMAGING General Features • Best diagnostic clue ○ Complex, multiloculated, cystic mass in liver, often with septations and mural calcifications • Location ○ Right lobe (55%), left lobe (29%), both lobes (16%) ○ Arising from – Intrahepatic biliary ducts (83%) – Extrahepatic bile ducts (13%) – Gallbladder (0.02%) • Size ○ 1.5-25 cm in diameter – Usually large at time of diagnosis if symptomatic • Key concepts ○ Biliary cystadenocarcinoma – Malignant transformation of benign biliary cystadenoma – Typically solitary tumor; usually multilocular, but sometimes unilocular – Tumor is encapsulated – Usually seen in middle-aged women – Recurs after incomplete excision ○ Benign biliary cystadenoma – Probably congenital in origin due to presence of aberrant bile ducts – Recurs after incomplete excision – Malignant potential to develop into cystadenocarcinoma even after years of stability ○ Benign and malignant lesions together account for only 5% of all intrahepatic lesions of bile duct origin ○ Microcystic cystadenoma variant – Composed of multiple small cysts – Glycogen-rich cystadenoma – Typical papillary and mesenchymal stromal features are not seen – Lined by single layer of cuboidal epithelial cells – Resembles serous microcystic adenoma of pancreas in pathology and on imaging

○ Mural or septal calcifications are common ○ Biliary dilatation (due to pressure effect) of IHBDs – Biliary obstruction considered to favor malignant tumor • CECT ○ Multilocular tumor – Nonenhancing cystic spaces – Enhancement of internal septa, capsule, and nodules – Enhancement of papillary excrescences – Mural or septal calcifications □ Less commonly, "honeycomb" or "sponge" appearance (microcystic variant) – Uncommonly has metastases or adenopathy at initial diagnosis ○ Unilocular tumor – Large or small nonenhancing cystic space – Enhancement of outer capsule and papillary excrescences – Fine mural calcifications

Liver

TERMINOLOGY

MR Findings • T1WI ○ Variable signal intensity locules depending on content of cystic fluid ○ High signal intensity (mucoid or hemorrhagic fluid) ○ Low signal intensity (serous fluid) ○ Septal or mural calcifications: Hypointense • T2WI ○ High signal intensity (serous fluid) ○ Low signal intensity (mucoid fluid) ○ Septa are well delineated ○ Septal or mural calcifications: Hypointense • T1WI C+ ○ Enhancement of capsule and septa

Ultrasonographic Findings • Grayscale ultrasound ○ Large, well-defined, multiloculated, anechoic mass ○ Highly echogenic septa ○ Tumor nodules or papillary growths ○ Mural or septal calcifications or fluid levels ○ Complex fluid: Areas of anechoic and internal echoes (cystic and hemorrhagic)

Angiographic Findings • Conventional ○ Avascular mass with small clusters of peripheral abnormal vessels in wall and septa ○ Stretching and displacement of vessels

Imaging Recommendations • Best imaging tool ○ Multiplanar CECT or MR

CT Findings • NECT ○ Large, well-defined, homogeneous, hypodense, waterdensity mass – Some are heterogeneous (cystic and hemorrhagic areas) ○ Cystadenocarcinoma: Septations and nodularity ○ Cystadenoma: Septations without nodularity

DIFFERENTIAL DIAGNOSIS Hemorrhagic or Infected Hepatic Cyst • • • • •

Complex heterogeneous cystic mass Multiple thick or thin septations May show mural nodularity and fluid level Calcification may be seen No enhancement of nodules or septa 833

Liver

Biliary Cystadenocarcinoma

• Hepatic cysts are usually multiple

Hepatic Pyogenic Abscess • Simple pyogenic abscess ○ Well-defined, round, hypodense mass (0-45 HU) • Cluster sign: Small abscesses aggregate, sometimes coalesce into single large septate cavity ○ Rim of abscess locules will enhance ○ Contents > water density, no enhancement, ± gas • Often associated with diaphragmatic elevation, atelectasis, and right-side pleural effusion

Cystic Metastases • Usually from ovarian cystadenocarcinoma or metastatic sarcoma • Show debris and mural nodularity • May have thick septa and wall enhancement • Usually multiple

Hydatid (Echinococcal) Disease • Large, well-defined, cystic liver mass • Often has numerous peripheral "daughter" cysts or scolices of different density or intensity • May show curvilinear or ring-like pericyst calcification • Occasionally dilated intrahepatic bile ducts ○ Due to pressure effect or rupture into ducts • May have extrahepatic foci of disease

PATHOLOGY General Features • Etiology ○ Malignant transformation of benign biliary cystadenoma by invasion of capsule ○ Biliary cystadenoma – Probably derived from ectopic nests of primitive biliary tissue

Demographics • Age ○ Peak incidence in 5th decade • Gender ○ Usually occurs in middle-aged women ○ Rare in men (< 10%) • Ethnicity ○ Predominantly seen in Caucasians • Epidemiology ○ Incidence: 5% of all intrahepatic cystic masses

Natural History & Prognosis • Complications ○ Rupture into peritoneum or retroperitoneum ○ Recurrence common – Almost inevitable unless entire rim of tumor is excised (often impossible due to adherence to vital hepatic vessels or inferior vena cava) • Prognosis ○ Tumors with ovarian stroma found in women have indolent course and good prognosis ○ Tumors without ovarian stroma found in both sexes have aggressive clinical course and poor prognosis

Treatment • Complete surgical resection

DIAGNOSTIC CHECKLIST Consider • Rule out other complex cystic masses of liver

Gross Pathologic & Surgical Features

Image Interpretation Pearls

• Solitary, multiloculated cystic tumor with well-defined thick capsule ○ Contents: Serous, mucinous, bilious, hemorrhagic, or mixed fluid • Surface is shiny, smooth, or bosselated • Polypoid excrescences and septations may be seen

• Large, well-defined, homogeneous or heterogeneous, complex cystic mass with septations and nodularity ○ Enhancing mural nodules suggest malignancy • May mimic hemorrhagic or infected hepatic cyst

Microscopic Features

1.

• Single layer of cuboidal or tall columnar biliary type epithelium with papillary projections • Malignant epithelial cells may line cysts • Subepithelial stroma resembles that of ovary ○ Common feature of cystic tumors throughout abdomen (e.g., mucinous cystic tumor of pancreas) • Usually mucinous, but serous type is also seen • Goblet cells, Paneth cells, and argyrophilic endocrine cells may be seen

2.

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Abdominal pain, obstructive jaundice, nausea, vomiting ○ Abdominal swelling with palpable mass (90%) 834

• Diagnosis: Fine-needle aspiration may yield fluid with CA19-9 ○ Results are not definitive, and cytology is inconclusive ○ Diagnosis is based mostly on imaging and resection with final pathology

SELECTED REFERENCES

3. 4. 5.

Arnaoutakis DJ et al: Management of biliary cystic Tumors: a multiinstitutional analysis of a rare liver tumor. Ann Surg. ePub, 2014 Chen YW et al: Surgical management of biliary cystadenoma and cystadenocarcinoma of the liver. Genet Mol Res. 13(3):6383-90, 2014 Cogley JR et al: MR imaging of benign focal liver lesions. Radiol Clin North Am. 52(4):657-82, 2014 Doepker M et al: Biliary cystadenoma: case series and review of the literature. Am Surg. 77(4):505-6, 2011 Sang X et al: Hepatobiliary cystadenomas and cystadenocarcinomas: a report of 33 cases. Liver Int. 31(9):1337-44, 2011

Biliary Cystadenocarcinoma Liver

(Left) Sonography in a 69-yearold woman with RUQ fullness and discomfort shows a complex cystic hepatic mass with fluid contents of slightly variable nature and multiple discrete septa. Mural nodularity within 1 of the larger cystic spaces strongly suggests a neoplastic etiology. (Right) Sagittal US in the same patient shows coarse septa within the cystic mass.

(Left) Axial T2WI MR of the same patient shows a complex cystic hepatic mass with fluid contents of a slightly variable nature and multiple discrete septa. (Right) Coronal T2WI MR of the same patient shows mural nodularity within 1 of the larger cystic spaces, strongly suggesting a neoplastic etiology. This proved to be a biliary cystadenoma with foci of cellular atypia in the mucosal lining.

(Left) Axial CECT in a middleaged woman with microcystic cystadenocarcinoma shows innumerable tiny cystic spaces with a "honeycomb" or sponge-like appearance reminiscent of serous microcystic adenoma of the pancreas. (Right) Gross pathology shows the cut surface of a resected mass, revealing innumerable small cystic spaces with a "honeycomb" or sponge-like appearance. Diagnosis was microcystic variant of biliary cystadenocarcinoma.

835

Liver

Biliary Cystadenocarcinoma

(Left) Axial CECT in a 47-yearold woman shows a complex cystic mass with foci of coarse calcification . (Right) CECT section shows more of the complex cystic mass , which was clearly separate from the gallbladder. This was interpreted as an "indeterminate mass" with a recommendation for followup, but no differential diagnosis nor recommended interval for follow-up was provided.

(Left) The same patient returned 5 years later with acute abdominal pain. Axial CECT shows a large, complex, multiseptate cystic mass with mural nodularity and solid components as well as focal calcifications . The presence of higher-thanwater-density fluid in the peritoneal cavity suggests that the mass has ruptured. (Right) Axial CT section shows more of the complex cystic mass, including solid mural nodularity , calcification, and exudative or hemorrhagic ascites.

(Left) Coronal-reformatted CT of the same patient shows the large mass with its mural nodularity and coarse calcification, along with complex ascites due to spontaneous rupture of the cystic tumor. (Right) Coronal CT section shows more of the mass and the focal calcification . At surgery (right trisegmentectomy), a ruptured biliary cystadenocarcinoma was confirmed. This lesion could have been resected 5 years earlier with much less morbidity and with a better prognosis.

836

Biliary Cystadenocarcinoma Liver

(Left) The initial CECT scan of this 56-year-old man shows a large cystic mass with septa . Note the proximity to, and mass effect on, the IVC and hepatic veins. (Right) CECT section in this patient shows an enhancing septum . At surgery, the mass was resected, but a portion of the posterior wall could not be resected completely due to the adjacent large veins.

(Left) Repeat CECT scan 1 year later in the same patient shows recurrence of a septate cystic mass. Portions of the radiopaque staple line are visible. (Right) CECT section in the same study shows the surgical staple line and a multiseptate cystic mass very similar in size and appearance to the tumor seen before surgery. Incompletely resected biliary cystadenomas and cystadenocarcinomas often recur.

(Left) CECT section from the same study shows dilation of intrahepatic bile ducts , which can be considered a bad prognostic sign of invasion, and a malignant character of cystic hepatic tumors. (Right) The classic spindled and cellular ovarian-type stroma is seen underneath the cyst lining of a biliary cystadenoma. (Courtesy M. Yeh, MD, PhD.)

837

Liver

Hepatic Angiosarcoma KEY FACTS

IMAGING • Highly aggressive malignancy with several morphological types • 3 patterns ○ Multifocal hypervascular masses in liver ± spleen – May have peripheral and delayed enhancement that simulate hemangiomas ○ Single/multiple hepatic masses, variable necrosis ○ Diffuse infiltration of liver; micronodular • Often metastatic to spleen, nodes, lungs, bones

PATHOLOGY • Etiology ○ Environmental carcinogens and drugs – Polyvinyl chloride, arsenicals, steroids

TOP DIFFERENTIAL DIAGNOSES

CLINICAL ISSUES

• Hepatic cavernous hemangioma ○ Centripetal nodular enhancement that approximates density of blood on all phases ○ More homogeneously intense on T2WI than angiosarcoma • Hepatic metastases and lymphoma

• Presentation ○ Rapid and early metastatic spread – Spleen, lung, bone marrow, nodes, peritoneum • Prognosis ○ Poor; death within 1 year

(Left) Cross section from a partial hepatectomy for angiosarcoma shows numerous cystic, blood-filled spaces. (Courtesy C. Trower, PA [ASCP] and A. Folpe, MD.) (Right) Markedly atypical neoplastic endothelial cells line vascular spaces. Note that the normal hepatic architecture has been destroyed. (Courtesy L. Lamps, MD.)

(Left) Axial CECT shows dozens of vascular masses in the liver (and spleen) that have marked but irregular enhancement. Some portions of some lesions simulate the nodular peripheral pattern of enhancement seen with hemangiomas, but the lesions do not meet other criteria for benign lesions. (Right) Axial CECT in the same patient shows an additional lesion with similar enhancement and morphology in the spleen . Biopsy specimen of a liver lesion confirmed the diagnosis of angiosarcoma.

838

○ Hypervascular metastases: Hyperdense in late arterial phase; usually hypo- or isodense on portal venous and delayed phase • Hepatocellular carcinoma ○ Heterogeneous hypervascular mass(es), vascular invasion, cirrhotic liver

Hepatic Angiosarcoma

Abbreviations • Angiosarcoma (AGS)

Synonyms • Hemangioendothelial sarcoma, hemangiosarcoma, Kupffer cell sarcoma

IMAGING General Features • Best diagnostic clue ○ Heterogeneous, hypervascular, multifocal malignancy

CT Findings • 3 patterns ○ Multifocal hypervascular masses in liver ± spleen, other organs – May have peripheral and delayed enhancement that simulates hemangiomas ○ Single or multiple hepatic masses with variable necrosis ○ Diffuse infiltration of liver; micronodular • Often metastatic to nodes, lungs, bones

MR Findings • Hemodynamics and morphology similar to those on CT • Bright on T2WI, usually less than for hemangioma

Imaging Recommendations • Best imaging tool ○ Triphasic helical CT or MR

DIFFERENTIAL DIAGNOSIS Hepatic Cavernous Hemangioma • Centripetal nodular enhancement that approximates density of blood on all phases of enhancement • More homogeneously intense on T2WI than AGS • Hemangiomas are rarely as numerous as with AGS

Hepatic Metastases and Lymphoma

Gross Pathologic & Surgical Features • Nonencapsulated mass(es) containing large cystic areas filled with bloody debris and necrosis

Microscopic Features • Malignant endothelial cells lining vascular channels • Fibrosis and hemosiderin in solid portions of tumor

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Weakness, weight loss, abdominal pain, hepatomegaly in older patients • Clinical profile ○ Rapid and early metastatic spread: Spleen (16%), lung, bone marrow, porta hepatis nodes, kidneys, peritoneum – Portal vein invasion/hemorrhagic ascites ○ Lab data: Elevation of serum neuron-specific enolase; no elevation of -fetoprotein

Demographics • Age ○ Any age – Peak incidence in 6th-7th decades • Gender ○ M:F = 4:1 • Epidemiology ○ Most common mesenchymal tumor of liver ○ Up to 2% of all primary malignant liver tumors ○ 30x less common than hepatocellular carcinoma

Natural History & Prognosis • Prognosis is poor; death within 1 year

Treatment • Surgical resection: Tumor confined to 1 lobe of liver • Systemic or hepatic arterial chemotherapy: Antiangiogenic therapy

DIAGNOSTIC CHECKLIST

• Hypervascular metastases: Hyperdense in late arterial phase; usually hypo- or isodense on portal venous and delayed phase

Consider

Hepatocellular Carcinoma

Image Interpretation Pearls

• Heterogeneous hypervascular mass(es) with washout ± capsule • Usually occurs in setting of known cirrhosis

• Consider in any aggressive, multifocal, hypervascular tumor with variable morphology

• Diagnosis is rarely established by imaging alone

SELECTED REFERENCES

PATHOLOGY

1.

General Features

2.

• Etiology ○ Environmental carcinogens – Polyvinyl chloride, arsenicals, Thorotrast ○ Drugs: Cyclophosphamide, anabolic steroids – Diethylstilbestrol, oral contraceptives ○ Post radiation (median latency: 74 months) • Associated abnormalities ○ Neurofibromatosis type 1

Liver

TERMINOLOGY

3.

4. 5.

Groeschl RT et al: Does histology predict outcome for malignant vascular tumors of the liver? J Surg Oncol. 109(5):483-6, 2014 Orlando G et al: Hepatic hemangiosarcoma: an absolute contraindication to liver transplantation--the European Liver Transplant Registry experience. Transplantation. 95(6):872-7, 2013 Chung EM et al: From the archives of the AFIP: Pediatric liver masses: radiologic-pathologic correlation. Part 2. Malignant tumors. Radiographics. 31(2):483-507, 2011 Geramizadeh B et al: Hepatic angiosarcoma of childhood: a case report and review of literature. J Pediatr Surg. 46(1):e9-11, 2011 Schwartz J et al: Education and Imaging. Hepatobiliary and pancreatic: angiosarcoma of the liver. J Gastroenterol Hepatol. 25(5):1016, 2010

839

Liver

Hepatic Angiosarcoma

(Left) Axial T1WI MR in a 40year-old woman with palpable abdominal mass shows a low signal intensity mass involving both the left and right lobes. The focal areas of high signal represent vascular spaces with slow flow. (Right) Axial T2WI MR in the same patient shows that the mass is of heterogeneous high signal intensity.

(Left) Axial CECT in a 70-yearold woman with malaise and weight loss shows 1 of several multiple hepatic masses with heterogeneous enhancement. (Right) Axial CECT in the same patient shows that some of the masses have a suggestion of nodular peripheral enhancement , whereas other lesions appear as nonspecific, heterogeneous, hypodense masses typically seen with metastases.

(Left) Axial CECT in the same patient shows that some tumors are either too small to characterize or appear as heterogeneous solid masses . (Right) Axial CECT in the same patient shows that other metastases have a complex cystic appearance , illustrating the spectrum of morphologic patterns seen with angiosarcoma.

840

Hepatic Angiosarcoma Liver

(Left) Axial CECT in a 69-yearold man with abdominal pain and weight loss shows heterogeneous, hypervascular malignancy in multiple sites, including the spleen and an anterior rib . (Right) Axial CECT in the same patient shows more of the splenic tumor and subtle, small masses in the liver .

(Left) Axial CECT in the same patient shows multifocal hypervascular tumors in the spleen , liver , and right kidney . (Right) Axial CECT in the same patient shows more of the multifocal malignancy in the spleen and kidney .

(Left) Coronal reformatted CECT in the same patient shows multifocal malignancy within the liver , spleen , and kidney . (Right) Coronal CECT in the same patient shows additional tumors seen in liver , spleen , and kidney . The tumors do not fulfill the strict imaging criteria for hemangioma, including nodular peripheral enhancement that is isodense to blood vessels. Angiosarcoma is a very rare and aggressive tumor that is usually fatal within 1 year of diagnosis.

841

Liver

Undifferentiated Sarcoma KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Synonym ○ Undifferentiated embryonal sarcoma • Definition ○ Primary malignant tumor of liver composed of primitive mesenchymal cells with partial, divergent differentiation

• Metastases and lymphoma, hepatic • Hydatid (echinococcal) disease • Angiosarcoma, liver

IMAGING • Large, encapsulated, spherical mass • May have peripheral rim of viable, hypervascular tumor • Often has large complex, cystic spaces with focal hemorrhage • May show signs of vascular invasion ○ Hepatic, portal vein, or inferior vena cava (IVC) invasion • Large subcapsular tumors may rupture • Nodal or distant metastases are common ○ Lung and osseous mets are most common

(Left) Axial T2WI MR in a 57year-old woman shows a huge hepatic mass that replaces most of the right lobe. The mass is heterogeneously hyperintense, though not as bright as another lesion that proved to be a cavernous hemangioma. (Right) Axial T1WI C+ MR in the same case shows nodular peripheral enhancement of the hemangioma , whereas most of the sarcoma shows no enhancement. The tumor is an undifferentiated sarcoma, which is largely necrotic and hemorrhagic as suggested by MR.

(Left) Axial arterial phase CECT in a 73-year-old man shows a large, encapsulated mass that has central necrosis and a periphery of hypervascular solid tumor, a common feature of sarcomas in general, though not specific for a primary hepatic sarcoma. (Right) Coronal CT reconstruction in the same case shows the large, centrally necrotic hepatic sarcoma . Absence of immunohistochemical evidence of muscle, epithelial, or vascular differentiation led to the final diagnosis of undifferentiated sarcoma.

842

CLINICAL ISSUES • • • • •

Majority of patients are children (ages 6-10) Comprises 6-13% of primary hepatic neoplasms in children Rare reports in adults of all ages Generally grim prognosis; 5-year survival averages ~ 15% Resection ± adjuvant or neoadjuvant therapy have recently improved prognosis

DIAGNOSTIC CHECKLIST • Check for primary extrahepatic tumor • Metastases are much more common cause of complex cystic hepatic tumors

Undifferentiated Sarcoma

Synonyms • Undifferentiated embryonal sarcoma • Malignant mesenchymoma

Angiosarcoma, Liver • May be indistinguishable by imaging and light microscopy • Immunohistochemical analysis may be definitive

PATHOLOGY

Definitions

Gross Pathologic & Surgical Features

• Primary malignant tumor of liver composed of primitive mesenchymal cells with partial, divergent differentiation

• Solitary, well demarcated, large • Some solid areas, but mostly gelatinous, cystic areas with focal hemorrhage and necrosis

IMAGING General Features • Best diagnostic clue ○ Large, spherical, encapsulated necrotic or complex cystic mass • Location ○ Right lobe predilection • Size ○ Usually large (9-30 cm) at time of diagnosis • Morphology ○ Spherical

CT Findings • Large, encapsulated, spherical mass • May have peripheral rim of viable, hypervascular tumor • Often has large complex, cystic spaces with focal hemorrhage • May show signs of vascular invasion ○ Hepatic, portal vein, or inferior vena cava (IVC) invasion • Large subcapsular tumors may rupture • Nodal or distant metastases are common ○ Lung and osseous mets are most common

MR Findings • Large, encapsulated, spherical mass • Central necrosis, hemorrhage, cystic degeneration ○ These areas are heterogeneously bright on both T1- and T2WI

Microscopic Features • Spindled, oval, or stellate tumor cells in myxoid stroma • Marked nuclear pleomorphism and mitotic activity • Foci of extramedullary hematopoiesis (in up to 50% of cases) • Immunohistochemistry ○ Tumor cells stain positive for -1-antitrypsin and -1antichymotrypsin ○ Characteristic PAS(+) cytoplasmic and extracellular eosinophilic globules

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Vague right upper quadrant (RUQ) discomfort ○ Subcapsular tumor may rupture severe pain and hypotension • Other signs/symptoms ○ Jaundice, dyspnea (with IVC compression or invasion)

Demographics • Majority of patients are children (ages 6-10) ○ Comprises 6-13% of primary hepatic neoplasms in children • Rare reports in adults of all ages • Equal gender distribution

Natural History & Prognosis

Ultrasonographic Findings

• Generally grim prognosis; 5-year survival averages ~ 15%

• Large, complex, cystic-appearing mass

Treatment

Imaging Recommendations

• Resection ± adjuvant or neoadjuvant therapy ○ Recent studies suggest improved survival • Liver transplantation has been used in children with encouraging short-term success

• Best imaging tool ○ Multiplanar, multiphasic CECT or MR

DIFFERENTIAL DIAGNOSIS Metastases and Lymphoma, Hepatic • Metastases from primary cystic tumor (e.g., ovarian cystadenocarcinoma) • Metastases from other tumors, with spontaneous or therapy-induced necrosis ○ e.g., metastatic sarcoma, gastrointestinal stromal tumor (GIST) ○ Immunohistochemical differentiation (e.g., C-Kit for GIST)

Hydatid (Echinococcal) Disease

Liver

TERMINOLOGY

DIAGNOSTIC CHECKLIST Consider • Check for primary extrahepatic tumor ○ Metastases are much more common cause of complex cystic hepatic tumors

SELECTED REFERENCES 1.

Ismail H et al: Treatment of undifferentiated embryonal sarcoma of the liver in children--single center experience. J Pediatr Surg. 48(11):2202-6, 2013

• Several cases have been reported in which hepatic sarcomas were misdiagnosed as hydatid cysts ○ Presence of large, encapsulated, complex cystic mass with internal debris 843

Liver

Hepatic Metastases and Lymphoma KEY FACTS

IMAGING • Hepatic lymphoma ○ Diffuse infiltration and low density on NECT ○ Multiple well-defined, homogeneous, low-density (CECT) or high-intensity (T2WI) masses • Liver metastases ○ Hypovascular metastases: Low-density center with peripheral rim or target-like enhancement ○ Hypervascular metastases: Hyperdense (intense) on arterial phase CECT or CEMR • Cystic metastases (< 20 HU) ○ Fluid levels, debris, mural nodules • Liver-specific MR contrast agents (e.g., gadoxetate) ○ Metastases: Hypointense lesions made more apparent compared with bright enhancement of liver on delayed phase imaging • CECT is usually best as "whole body" screening test ○ Even better if combined as PET/CT

(Left) Axial CECT shows multiple spherical liver lesions with a "target" appearance. This is the most typical appearance for liver metastases, especially from colon cancer. Also note the focally dilated bile ducts due to compression by the metastases. (Right) Color Doppler ultrasound in the same patient shows multiple spherical liver lesions with a "target" appearance , some containing visible blood vessels . This is the typical appearance of metastatic colorectal carcinoma.

(Left) Axial T1WI C+ MR in a patient with metastatic colon cancer shows multiple liver metastases with several typical features, including a continuous ring of enhancement . (Right) Axial T2WI FS MR in the same patient shows heterogeneous hyperintensity within the hepatic metastases . Most metastases are heterogeneously hyperintense on T2WI and hypovascular and hypointense on T1WI.

844

○ Metastases and lymphoma are usually FDG-avid masses within liver • Decision for thermal ablation or surgical resection ○ May require most sensitive tests (gadoxetate-enhanced MR, PET/CT, or intraoperative US)

TOP DIFFERENTIAL DIAGNOSES • Multifocal fatty infiltration (steatosis) • Multiple benign masses • Multifocal hepatocellular carcinoma or cholangiocarcinoma

DIAGNOSTIC CHECKLIST • In absence of a known primary tumor or other metastases: ○ Hepatic lesions that are "too small to characterize" rarely represent metastases ○ Lesions that are lower than blood density on NECT rarely represent metastases

Hepatic Metastases and Lymphoma

General Features • Best diagnostic clue ○ Lymphoma: Lobulated, low-density, hypovascular masses ○ Metastases: Multiple heterogeneous, spherical lesions scattered throughout liver • Morphology ○ Usually spherical • Key concepts ○ Hepatic lymphoma – Primary (rare) – Secondary (more common): Seen in > 50% of patients with Hodgkin disease (HD) or non-Hodgkin lymphoma (NHL) ○ Liver metastases – Most common malignant tumor of liver □ Compared to primary malignant tumors (18:1) – Liver is 2nd only to regional lymph nodes as site of metastatic disease – Autopsy studies reveal 55% of oncology patients have liver metastases

CT Findings • NECT ○ Lymphoma – Diffuse infiltration: Indistinguishable from normal liver or steatosis ○ Metastases – Isodense, hypodense, or hyperdense (melanin or calcification) • CECT ○ Lymphoma – Diffuse infiltration and low density – Multiple well-defined, homogeneous, low-density masses ○ Hypovascular metastases – Low-attenuation center with peripheral rim enhancement (e.g., epithelial metastases) – Indicates vascularized viable tumor in periphery and hypovascular or necrotic center – Rim enhancement may also be due to compressed normal parenchyma ○ Hypervascular metastases – Hyperdense in late arterial phase images – May have internal necrosis without uniform hyperdense enhancement – Hypo-/isodense on NECT and portal venous phase □ Often washout to become hypodense on delayed phase CECT – Examples: endocrine (islet cell), carcinoid, thyroid and renal carcinomas, and pheochromocytoma ○ Cystic metastases (< 20 HU) – Fluid levels, debris, mural nodules

MR Findings • T1WI ○ Lymphoma and metastases: Hypointense lesions – Melanoma metastases: Hyperintense due to melanin • T2WI ○ Lymphoma: Focal or diffusely hyperintense

○ Metastases – Moderate to high signal – Light bulb sign: Very high signal intensity (e.g., cystic and neuroendocrine metastases) □ Mimic cysts or hemangiomas but usually with thick wall or fluid level • T1WI C+ ○ Hypovascular metastases – Same pattern of enhancement as CECT – Low signal in center and peripheral rim enhancement – Perilesional enhancement may be tumor vascularity or hepatic edema ○ Hypervascular metastases – Hyperintense enhancement on arterial phase • Hepatobiliary contrast agents (e.g., gadoxetate [Eovist, Primovist]) ○ On delayed scans, normal liver is brightly enhanced ○ Metastases are conspicuous as hypointense focal lesions ○ Most sensitive, but not specific, imaging test for determining presence and number of metastases

Liver

IMAGING

Ultrasonographic Findings • Grayscale ultrasound ○ Hepatic lymphoma – Multiple well-defined, hypoechoic lesions – Diffuse form: May detect innumerable subcentimeter hypoechoic foci □ Otherwise indistinguishable from normal or fatty liver ○ Hypoechoic metastases – Usually from hypovascular tumors ○ Hyperechoic metastases – GI tract malignancy – Vascular metastases ○ Bull's-eye or "target" metastatic lesions – Alternating layers of hyper- and hypoechoic tissue – Solid mass with hypoechoic rim or halo – Usually from aggressive primary tumors ○ Cystic metastases – Almost all show complex walls and contents ○ Calcified metastases – Markedly echogenic with acoustic shadowing

Nuclear Medicine Findings • PET ○ Lymphoma and metastases – FDG-18-avid focal lesions – Excellent staging tool for lymphoma and metastases □ High metabolic activity of liver may obscure some lesions

Imaging Recommendations • Best imaging tool ○ Meta-analysis of sensitivity for detection of colorectal metastases – Per patient basis □ Helical CECT: 65-72% (better if 45 g of IV iodine used) □ MR: 75-76% (much better if gadoxetate is used) □ PET: 90-95% – More recent studies of accuracy 845

Liver

Hepatic Metastases and Lymphoma □ Helical CT (80%), MR (92%) ○ CECT is usually best as "whole body" screening test – Even better if combined as PET CT ○ Decision for thermal ablation or surgical resection – May require most sensitive tests (gadoxetateenhanced MR, PET/CT, or intraoperative US) • Protocol advice ○ When to obtain biphasic (arterial and venous phase) CT – Known or suspected hypervascular primary tumor □ All "endocrine" tumors (e.g., thyroid, carcinoid, neuroendocrine pancreas, pheochromocytoma), renal cell carcinoma □ Some sarcomas, breast cancer, and melanoma metastases are best seen on arterial/biphasic CT scans

DIFFERENTIAL DIAGNOSIS

○ Nodular, infiltrative, expansile, or miliary

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic, RUQ pain, tender hepatomegaly ○ Weight loss, jaundice, or ascites • Lab data: Elevated liver function tests; normal in 25-50% of patients • Diagnosis: Imaging, core biopsy, and FNA

Demographics • Epidemiology ○ > 50,000 deaths per year in USA due to liver metastases from colorectal cancer alone

Natural History & Prognosis

• No peripheral rim or central enhancement • No mural nodules, debris, or enhancement

• Depends on primary tumor site • 20-40% have good 5-year survival rate if resectable • Resection plus chemotherapy offers excellent 5- and 10year survival in selected patients

Multifocal Fatty Infiltration (Steatosis)

Treatment

• Focal signal dropout on opposed-phase T1 GRE MR • Vessels course through "lesions" without disruption • Periligamentous, perivascular distribution

• Resection or ablation for colorectal liver metastases • Chemo- or radioembolization for hypervascular (carcinoid or endocrine) metastases • Chemotherapy (oral or IV) for all others

Multiple Hepatic Cysts

Multiple Hemangiomas • Typical peripheral, nodular, discontinuous enhancement on CECT or CEMR • Isodense with blood vessels on NECT and CECT • Markedly hyperintense on T2WI

Multifocal Hepatocellular Carcinoma (HCC) or Cholangiocarcinoma (CC) • HCC: Cirrhotic liver, vascular invasion • CC: Capsular retraction, delayed enhancement

Multiple Liver Abscesses • Cluster sign on CT for pyogenic abscesses • Often with atelectasis and right pleural effusion

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • In absence of known primary tumor or other metastases ○ Hepatic lesions that are "too small to characterize" rarely represent metastases ○ Lesions that are lower than blood density on NECT rarely represent metastases

SELECTED REFERENCES 1. 2.

PATHOLOGY General Features • Etiology ○ Hypovascular liver metastases, etiology – Lung, GI tract, pancreas, and most breast cancers – Lymphoma, bladder, and uterine malignancy ○ Hypervascular liver metastases, etiology – Endocrine tumors, renal and thyroid cancers – Some breast cancers, sarcomas, and melanomas • Associated abnormalities ○ Metastases: Check for extrahepatic primary tumor ○ Lymphoma: High-risk groups include patients with AIDS or transplant recipients

Staging, Grading, & Classification • Liver metastases indicate stage IV tumor

Gross Pathologic & Surgical Features • Lymphoma: Miliary, nodular, or diffuse form • Metastases vary in size, consistency, and vascularity 846

3.

4.

5.

Shin DS et al: Surgical resection of a malignant liver lesion: what the surgeon wants the radiologist to know. AJR Am J Roentgenol. 203(1):W21-33, 2014 Nishiwada S et al: Comparison between percutaneous radiofrequency ablation and surgical hepatectomy focusing on local disease control rate for colorectal liver metastases. Hepatogastroenterology. 61(130):436-41, 2014 Abu Hilal M et al: Oncological efficiency analysis of laparoscopic liver resection for primary and metastatic cancer: a single-center UK experience. Arch Surg. 147(1):42-8, 2012 Park SY et al: Radiofrequency ablation of hepatic metastases after curative resection of extrahepatic cholangiocarcinoma. AJR Am J Roentgenol. 198(1):2, 2012 Wang CC et al: An update on chemotherapy of colorectal liver metastases. World J Gastroenterol. 18(1):25-33, 2012

Hepatic Metastases and Lymphoma Liver

(Left) Ultrasound of a 60-yearold woman with a pancreatic endocrine tumor shows an echogenic mass near the confluence of hepatic veins that mimics the appearance of a hemangioma. (Right) Axial, venous phase CECT shows the same mass having the typical appearance of a metastasis, rather than a hemangioma. In an oncology patient, sonography is generally less reliable than CT or MR in detection and characterization of solid masses, though exceptions do occur.

(Left) Axial arterial phase CECT in a patient with a metastatic carcinoid tumor shows a hypervascular metastasis adjacent to the IVC. (Right) Axial portal venous CECT in the same patient shows the mass as nearly isodense to the liver and difficult to recognize. For hypervascular tumors, it is critical to obtain both arterial and venous phase images through the liver. Hypervascular tumors include primary HCC and adenomas; metastatic endocrine, renal, thyroid; and some melanoma sarcoma, and breast cancers.

(Left) Axial CECT in a patient with a metastatic gastric GIST shows a heterogeneous soft tissue density metastasis . (Right) Axial CECT in the same patient following treatment shows the metastasis as a near-water-density cystic mass , which could be mistaken for a simple cyst. Cystic metastases can result from a variety of primary tumors, especially sarcomas and cystadenocarcinomas of the ovary. Attention to details such as mural nodularity and comparison with prior imaging studies are key.

847

Liver

Hepatic Metastases and Lymphoma

(Left) Axial T1WI MR in a patient with metastatic melanoma shows multiple metastases that have the peculiar feature of being hyperintense on T1WI, which is attributed to the melanin in these lesions. Most metastases are hypo- or isointense to the liver on T1WI. (Right) Axial T2WI MR in the same patient shows the metastases , but they are nearly isointense to the liver except for foci of necrosis that are hyperintense .

(Left) Axial NECT in a patient with calcified metastases from colorectal cancer shows 1 of several calcified focal liver metastases . (Right) Axial portal venous CECT in the same patient shows many more metastases . The calcification is more difficult to recognize on this phase of CECT. Calcified metastases can result from several primary tumors, especially mucinous adenocarcinomas of the colon and ovary.

(Left) Axial CECT in a patient with metastatic breast cancer shows a dysmorphic liver with a lobulated and nodular contour . The presence of subtle hypodense lesions within the liver indicates widespread metastases. In response to chemotherapy, some have shrunk in size and become fibrotic, resulting in the appearance of pseudocirrhosis. (Right) More caudal section in the same patient shows the pseudocirrhosis pattern with widened fissures and peripheral nodularity with capsular retraction .

848

Hepatic Metastases and Lymphoma Liver

(Left) Axial T2WI of a 44-yearold man with colon cancer showed a total of 4 metastases , 3 of which are seen on this section. (Right) T1WI MR images obtained 20 minutes after the IV administration of gadoxetate (Eovist) revealed at least 3 additional metastases . Gadoxetate can make small metastases much more evident than on routine MR or CT evaluation. In this patient, the presence of 6 metastases precluded surgical or ablative therapy.

(Left) Axial NECT in a patient with metastatic breast cancer shows an enlarged lowattenuation liver that might be misinterpreted as steatosis. (Right) Axial CECT in the same patient shows innumerable hypervascular liver metastases . Ascites is also present. Diffuse metastases that simulate hepatic steatosis can be seen with a variety of primary tumors, including breast, melanoma, and especially lymphoma.

(Left) Axial CECT of a 59-yearold woman with breast cancer and liver disfunction shows poorly defined low density replacing most of the right lobe of the liver, in a pattern suggesting steatosis or widespread metastases. (Right) One week later, a PET/CT scan was performed. Axial fused PET/CT images show that the abnormal portions of the liver are FDG avid, indicating malignant disease (metastases). PET/CT can be valuable in detection of subtle or diffuse liver metastases or lymphoma.

849

Liver

Hepatic Metastases and Lymphoma

(Left) Axial NECT in a patient with metastatic melanoma shows subtle hypodense metastases and others that are hyperdense . Melanoma is one of the few metastases that may be hyperdense to normal-attenuation liver; almost any metastases can be hyperdense to fatty liver. (Right) Axial CECT in a patient with spontaneous bleeding shows a sentinel clot adjacent to a liver mass , indicating this as the source of bleeding. Also note hemoperitoneum ,a relatively rare complication of liver metastases.

(Left) Axial T1WI C+ MR in a patient with hepatic lymphoma shows a large, heterogeneously hypointense mass . (Right) Axial T2WI FS MR in the same patient shows that the large solitary mass is heterogeneously hyperintense .

(Left) Axial CECT in a patient with diffuse hepatic lymphoma shows innumerable small foci of tumor in the liver and spleen. On NECT, the liver appeared diffusely enlarged and low in attenuation, resembling benign steatosis. (Right) Axial CECT in a patient with NHL and AIDS shows multifocal hypodense masses in the liver and spleen. Similar masses were present in the kidneys and in multiple nodal groups. AIDS patients and transplant recipients are at high risk for developing non-Hodgkin lymphoma.

850

Hepatic Metastases and Lymphoma Liver

(Left) Axial CECT of a 60-yearold man with melanoma and abnormal liver function shows that the liver is enlarged and diffusely decreased in attenuation, consistent with diffuse tumor or steatosis. Subtle focal hypodense lesions are also seen. (Right) CECT section in the same patient shows more of the diffusely low-attenuation liver.

(Left) Additional focal hypodense lesions are seen , but these are still consistent with focal steatosis or metastases. (Right) Longitudinal sonogram shows innumerable hypoechoic lesions , many of them are < 1 cm in diameter. Focal steatosis would be echogenic; therefore, these lesions are likely to represent metastases (proven on biopsy).

(Left) Another longitudinal US image shows more of the innumerable hypoechoic metastases, many more than suggested by CT. (Right) Color Doppler US shows vascularity within and around some of the metastases.

851

SECTION 10

Biliary System

Introduction and Overview Imaging Approach to the Biliary System

854

Normal Variants and Artifacts Biliary Normal Variants and Artifacts

862

Congenital Congenital Abnormalities of the Gallbladder Caroli Disease Choledochal Cyst

866 870 874

Infection Recurrent Pyogenic Cholangitis Ascending Cholangitis Pancreatobiliary Parasites AIDS Cholangiopathy Gallbladder Hydrops and Empyema

878 882 886 890 892

,QƮDPPDWLRQ Gallstones and Sludge Acute Calculous Cholecystitis Acalculous Cholecystitis Xanthogranulomatous Cholecystitis Emphysematous Cholecystitis Mirizzi Syndrome Hyperplastic Cholecystoses Porcelain Gallbladder Milk of Calcium Bile Autoimmune (IgG4) Cholangitis Primary Sclerosing Cholangitis

896 902 906 910 914 918 922 926 928 930 934

Degenerative Biloma

938

Vascular Disorders Ischemic Bile Duct Injury

942

Trauma Biliary Trauma

946

Treatment Related Chemotherapy-Induced Cholangitis

950

Benign Neoplasms and Tumor-Like Conditions Gallbladder Polyps

952

Malignant Neoplasms Gallbladder Carcinoma

956

Ampullary Carcinoma

960

Biliary Metastases and Lymphoma

964

Biliary Papillomatosis

965

Biliary IPMN

966

Biliary System

Imaging Approach to the Biliary System

Imaging Indications and Protocols Oral and IV cholangiography have been supplanted by newer cross-sectional imaging and cholescintigraphy. MR hepatobiliary IV contrast agents may be used to supplement CT or MR cholangiography. Cholescintigraphy is a nuclear medicine study to evaluate the morphology and function of the biliary tree. In a "HIDA scan," the patient receives an IV administration of Tc-99m iminodiacetic acid compound; an agent that has rapid uptake by the liver and excretion in the bile. A normal study has a hepatic parenchymal phase followed by identification of the radiotracer within the gallbladder (GB), indicating a patent cystic duct, and subsequent passage into the duodenum, indicating a patent common duct. While the anatomic detail of a HIDA scan is limited, the functional information is valuable in diagnosing cystic duct or common duct occlusion, or a biliary leak. Ultrasonography is the primary imaging modality for most GB and biliary abnormalities. US detects gallstones within the GB with almost 100% accuracy. The diagnosis of acute cholecystitis is established with only slightly less accuracy based on the findings of gallstones, GB wall thickening, and focal tenderness over the GB (the sonographic Murphy sign). US may also allow diagnosis of complications of cholecystitis, such as gangrene or perforation, although, CT is often better suited for the evaluation of disease beyond the GB wall. GB wall mass lesions, such as polyps and carcinoma, are also well depicted by US. CT is less sensitive than US in diagnosis of gallstones, because the attenuation of gallstones may vary from less than water to densely calcified. Furthermore, CT detects sludge (the viscous, echogenic layer of material within the GB that is often present in fasting patients and those with GB dysfunction) much less frequently than US. CT is accurate in diagnosing complications of acute cholecystitis and in revealing the mass (biliary, hepatic, or pancreatic), which is the usual cause of painless jaundice. Newer thin section and multiplanar CT detects > 70% of stones in choledocholithiasis and shows indirect signs, such as abrupt narrowing of the common bile duct (CBD), in a higher percentage of cases. CT or MR is the primary modality for diagnosis and staging of pancreaticobiliary neoplasms. Multiplanar displays, especially along the course of the biliary and pancreatic ducts and vessels, are especially effective in providing findings that have an impact on diagnosis and management of pancreaticobiliary diseases. CT cholangiography is a noninvasive alternative to direct or MR cholangiography and is useful for the preoperative evaluation of the biliary anatomy in a potential living liver donor, as some common ductal anomalies may preclude or complicate this procedure. A standard CT scan, with and without IV contrast, is initially performed using the conventional nonionic contrast media. Next, a slow IV drip infusion of iodipamide is performed with delayed CT imaging, and multiplanar reformations of the opacified biliary tree are obtained. Spatial resolution usually exceeds that of MR cholangiopancreatography (MRCP) but is less than that of direct cholangiography. MR cholangiopancreatography (MRCP) has largely supplanted endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of lesions affecting the biliary or pancreatic ducts. MRCP is a primary tool in the evaluation of biliary obstruction (from calculi or intrinsic and extrinsic

854

masses), while ERCP is usually reserved for interventions, such as the placement of a biliary stent to bypass an obstructed bile duct. MRCP utilizes a variety of heavily T2-weighted sequences to show the bile (and pancreatic duct) as bright signal fluid. While spatial detail is limited, it is usually sufficient to establish the diagnosis and guide management. MRCP can also be combined with other sequences in multiple planes to yield comprehensive evaluation of the liver, biliary tree, and pancreas. The IV administration of gadoxetate (Eovist or Primovist) allows high-quality MR evaluation of the hepatic parenchyma during the arterial and venous phases of imaging, and delayed imaging can provide unique advantages over the usual gadolinium-based contrast media for some specific indications. Imaging after a 20-minute delay shows dense enhancement of normal hepatic parenchyma, as well as enhancement of the biliary tree (due to the 50% hepatobiliary rate of excretion). This allows for better quality MR cholangiography for such indications as preoperative evaluation of potential hepatic donation, biliary leaks following trauma or surgery, and biliary obstruction. The presence of hepatic dysfunction (e.g., with elevated serum bilirubin) may impair the quality of the cholangiographic phase of a gadoxetate-enhanced MR scan. Direct cholangiography retains an important role in the diagnosis and treatment of biliary disease. Percutaneous transhepatic cholangiography (PTC) is the optimal modality for patients with known or suspected biliary obstruction, especially when ERCP is unavailable (e.g., following prior surgical biliary diversion) or to diagnose, stage, and treat intrahepatic or proximal extrahepatic biliary obstruction (e.g., a Klatskin tumor). Endoscopic retrograde cholangiopancreatography (ERCP) is performed for known or suspected biliary obstruction that may require endoscopic placement of a biliary stent, retrieval of stones, or the acquisition of a biopsy specimen or brush cytology/histology confirmation of malignancy. ERCP is also the modality of choice for diagnosis and treatment of traumatic or postsurgical bile leaks, which will usually resolve following placement of a biliary stent. Postoperative ("T-tube") cholangiography is a valuable and easy means of evaluating a biliary tree that has been altered by surgery (e.g., liver transplantation, choledochoenterostomy) when the surgeon has left a tube in place within the CBD with an external limb that can be accessed for injection of contrast medium. A T-tube cholangiogram allows for convenient and safe diagnosis of retained stones, leaks, or strictures.

Imaging Evaluation of the Jaundiced Patient A patient who has jaundice or significant elevation of liver function tests, especially alkaline phosphatase or bilirubin, either has biliary obstruction or severe diffuse hepatic disease. The role of the radiologist in this setting is to determine the presence, level, and cause of biliary obstruction. Criteria for diagnosing biliary dilation vary somewhat among investigators and according to the age of the patient. As a general rule, the presence of visible continuous arborization (branching) of the intrahepatic ducts indicates dilation. The bile ducts course along the portal triads and should not be >

Imaging Approach to the Biliary System

The character of the transition from a dilated to narrow duct is an important criterion. Abrupt narrowing is usually due to tumor, stone, or iatrogenic injury, while tapered narrowing is more commonly due to inflammation, such as from pancreatitis or cholangitis. Malignant tumors also cause eccentric narrowing of the duct and a mass in or around the duct and may be associated with other signs of "invasiveness," such as vessel encasement. The level of the obstruction is determined by the point of transition from dilated to narrowed ducts. Intrahepatic causes of obstruction include primary sclerosing cholangitis and liver tumors, usually malignant. Porta hepatis obstruction is most commonly due to cholangiocarcinoma (Klatskin tumor). Primary sclerosing cholangitis, gallbladder carcinoma, metastases, or iatrogenic injury (usually from a laparoscopic cholecystectomy) are other etiologies that may result in obstruction at the porta hepatis. Intrapancreatic causes of obstruction include pancreatic carcinoma, chronic pancreatitis, CBD stones, cholangiocarcinoma, and ampullary lesions (dysfunction or tumor).

Differential Diagnosis Distended Gallbladder Common • Cholecystitis • Prolonged fasting • Hyperalimentation • Postvagotomy state • Anticholinergic medication • Diabetes mellitus • Obstruction of common bile duct • Alcoholism • Acute pancreatitis • Hepatitis Less Common • Hydrops and empyema, gallbladder • Autoimmune (IgG4-related) pancreatitis • AIDS cholangiopathy • Choledochal cyst (mimic) Gas in Bile Ducts or Gallbladder Common • Sphincterotomy • Choledocholithiasis • Patulous sphincter of Oddi • Biliary-enteric anastomosis • Portal vein gas (mimic) Less Common • Emphysematous cholecystitis • Gas within gallstones • Duodenal diverticulum • Gallstone ileus • Crohn disease

• Duodenal ulcer • Recurrent pyogenic cholangitis Diffuse Gallbladder Wall Thickening Common • Cholecystitis • Hepatitis • Cardiac, renal, or liver failure • Systemic hypervolemia, abdominal signs

Biliary System

40% the diameter of the adjacent portal vein. The common hepatic duct should measure < 6 mm at the porta hepatis and the common bile duct < 8 mm, although, it commonly measures up to 10 mm in elderly patients who have had a prior cholecystectomy. Dilation of the extrahepatic ducts should always be correlated with any clinical or biochemical evidence of obstruction before recommending extensive evaluation.

Less Common • Hyperplastic cholecystosis • Gallbladder carcinoma • AIDS cholangiopathy • Primary sclerosing cholangitis • Acute pancreatitis • Duodenal ulcer • Pyelonephritis • Porcelain gallbladder • Gallbladder wall varices Focal Gallbladder Wall Thickening Common • Hyperplastic cholecystosis • Gallbladder carcinoma Less Common • Xanthogranulomatous cholecystitis • Porcelain gallbladder • Metastases and lymphoma, gallbladder • Gallbladder wall polyps • Epithelial polyps, gallbladder • Mesenchymal tumor, gallbladder • Intramural hematoma, gallbladder High-Attenuation (Hyperdense) Bile in Gallbladder Common • Vicarious excretion • Layering of small gallstones • Post cholangiography • Biliary stent Less Common • Gallbladder sludge • Trauma, biliary • Trauma, hepatic • Milk of calcium bile • Biliary-enteric fistula or anastomosis • Porcelain gallbladder (mimic) • Gallbladder carcinoma (mimic) • Hemorrhage cholecystitis Dilated Common Bile Duct Common • Choledocholithiasis • Postcholecystectomy dilated CBD • Senescent change, CBD • Chronic pancreatitis Less Common • Other pancreatic neoplasms • Gallbladder carcinoma • Primary sclerosing cholangitis • Pancreatic pseudocyst • Infectious cholangitis • Biliary trauma • Small bowel obstruction • Choledochal cyst

855

Biliary System

Imaging Approach to the Biliary System

Asymmetric Dilation of Intrahepatic Bile Ducts Common • Primary sclerosing cholangitis • Cholangiocarcinoma • Ascending cholangitis • Hepatocellular carcinoma • Hepatic metastases and lymphoma • AIDS cholangiopathy Less Common • Recurrent pyogenic cholangitis • Pancreato-biliary parasites • Chemotherapy cholangitis • Hepatic hydatid cyst • IMPN, biliary Biliary Strictures, Multiple Common • Primary sclerosing cholangitis • Ascending cholangitis • Autoimmune (IgG4-related) cholangitis • Post-transplant liver • Cirrhosis (mimic)

(Left) Oblique grayscale ultrasound of gallbladder (GB) shows a distended gallbladder lumen with diffuse wall thickening , multiple gallstones , and pericholecystic fluid . Sonographic Murphy sign was positive. These are classic clinical and US features of acute cholecystitis. (Right) Tc99m HIDA scan shows flow of the radiotracer from the liver into the common bile duct (CBD) and bowel but not into the gallbladder, indicating obstruction of the cystic duct and indirectly suggesting acute cholecystitis.

(Left) This elderly woman has jaundice and RUQ pain. MR cholangiopancreatography (MRCP) shows numerous stones within the dilated CBD. The gallbladder is marked for identification. (Right) Endoscopic retrograde cholangiopancreatography (ERCP) in the same patient confirms the CBD stones . During the same procedure, a papillotomy was performed with balloon sweep clearing of the ductal stones followed by placement of a temporary plastic biliary stent. All symptoms resolved.

856

Less Common • AIDS cholangiopathy • Cholangiocarcinoma • Recurrent pyogenic cholangitis • Congenital hepatic fibrosis • Caroli disease • Chemotherapy cholangitis • Hepatic metastases (mimic) • Pancreato-biliary parasites

Selected References 1.

2.

3.

Chang JH et al: Role of magnetic resonance cholangiopancreatography for choledocholithiasis: analysis of patients with negative MRCP. Scand J Gastroenterol. 47(2):217-24, 2012 Drake LM et al: Accuracy of magnetic resonance cholangiopancreatography in identifying pancreatic duct disruption. J Clin Gastroenterol. 46(8):696-9, 2012 Frydrychowicz A et al: Gadoxetic acid-enhanced T1-weighted MR cholangiography in primary sclerosing cholangitis. J Magn Reson Imaging. Epub ahead of print, 2012

Imaging Approach to the Biliary System Biliary System

Ducts to segment 4 Right anterior-cephalic (segments 5 and 8) Right posterior-caudal (segments 6 and 7)

Ducts to segments 2 and 3 Left hepatic duct

Right hepatic duct

Minor papilla

Major papilla (hepatoduodenal papilla)

(Top) Note the distribution of the larger intrahepatic bile ducts. The CBD usually joins with the pancreatic duct in a common channel or ampulla (of Vater) but may enter the major duodenal papilla separately. The distal bile duct has a sphincteric coat of smooth muscle, the choledochal sphincter (of Boyden), which regulates bile emptying into the duodenum. When contracted, this sphincter causes bile to flow retrograde into the gallbladder for storage. The common hepaticopancreatic ampulla may be surrounded by a smooth muscle sphincter (of Oddi). (Bottom) Graphic shows common variations of cystic duct entry into common duct.

857

Biliary System

Imaging Approach to the Biliary System

(Left) In this 36-year-old man, CT shows gas and fluid within the GB and common duct due to the presence of a biliary stent (not shown). The GB wall is normal. (Right) In this 68-year-old man with diabetes and sepsis, CT shows gas within the lumen and wall of the GB with a hazy margin where the GB abuts the liver. This emphysematous cholecystitis was treated urgently with percutaneous cholecystostomy and later with cholecystectomy.

(Left) In this 50-year-old woman with acute cholecystitis, US shows a large echogenic stone with an acoustic shadow and a thickened GB wall (calipers). These findings, along with a positive sonographic Murphy sign, are diagnostic of acute cholecystitis. (Right) In this 35-year-old man with acute viral hepatitis, sonography shows a markedly thickened wall of the GB but no calculi. Hepatitis often shows massive GB wall thickening, along with periportal edema.

(Left) In this 68-year-old man, CT shows partial calcification of the GB wall. The GB wall that is adjacent to the liver is irregularly thickened, and the interface with the liver is quite irregular. (Right) Another CT section in the same patient shows tumor invasion of the adjacent liver by this GB cancer; the primary mass arises from the GB wall .

858

Imaging Approach to the Biliary System Biliary System

(Left) In this 42-year-old man, sonography shows a fundal mass with cystic components and echogenic foci that are associated with "comet tail" artifact . (Right) Coronal MRCP in the same patient shows foci of high T2 signal intensity within the fundus of the GB, representing dilated Rokitansky-Aschoff sinuses. These are characteristic features of fundal adenomyomatosis, a benign, hyperplastic cholecystosis.

(Left) A 64-year-old woman had this nonenhanced CT scan following angiography. Note the hyperdense bile within the GB , which is the result of vicarious excretion. The kidneys are persistently dense but not functioning due to acute renal failure. (Right) In this 80-year-old woman, nonenhanced CT shows a layer of nonopaque gallstones with milk of calcium bile both in a dependent and nondependent position within the GB.

(Left) In this elderly woman with no acute symptoms, CT shows dilation of the intrahepatic bile ducts . (Right) CT in the same patient shows evidence of a prior cholecystectomy with clips in the GB bed. Both intrahepatic and extrahepatic ducts are dilated to a degree beyond what is usually seen following cholecystectomy alone, but this patient had no evidence of biliary obstruction.

859

Biliary System

Imaging Approach to the Biliary System

(Left) In this 50-year-old man with chronic alcoholic pancreatitis, CT shows a heavily calcified and atrophic pancreas with dilation of the intrahepatic bile ducts . (Right) A more caudal CT section in the same patient shows the heavily calcified pancreas and more of the biliary ductal dilation .

(Left) Another more caudal CT section in the same patient shows several intra- and peripancreatic pseudocysts . (Right) MRCP in the same patient shows gross dilation of the pancreatic and bile ducts , along with the pseudocysts .

(Left) In this elderly man, CT shows intrahepatic ductal obstruction due to liver metastases from colon cancer. Note the dilated, arborizing ducts . (Right) In this 55-year-old woman, CT shows asymmetric dilation of the intrahepatic bile ducts due to a multifocal, peripheral (intrahepatic) cholangiocarcinoma .

860

Imaging Approach to the Biliary System Biliary System

(Left) In this elderly woman with recurrent pyogenic cholangitis, a T2W MR image shows dilated intrahepatic bile ducts . Within the dilated left lobe ducts there are numerous and large filling defects representing calculi . (Right) MRCP in the same patient confirms diffuse dilation of the intra- and extrahepatic ducts . The dilated left lobe ducts are less apparent because they are partially filled with stones and because they may be out of the plane of the MR section.

(Left) MRCP shows markedly dilated intrahepatic ducts and a normal CBD . The presence of severe dilation and abrupt transition at the confluence of the main left and right ducts suggest the diagnosis of Klatskin tumor (cholangiocarcinoma). (Right) Transhepatic cholangiogram in the same patient shows dilated intrahepatic ducts and complete obstruction at the confluence of the main ducts due to Klatskin tumor.

(Left) MRCP in the coronal plane shows multiple calculi within the dilated CBD. (Right) ERCP shows irregular arborization of the intrahepatic bile ducts with multiple strictures due to primary sclerosing cholangitis (PSC). The polypoid mass within the common bile duct is a cholangiocarcinoma, a known complication of PSC.

861

Biliary System

Biliary Normal Variants and Artifacts KEY FACTS

TERMINOLOGY • Variants and artifacts that may simulate pathology or potentially complicate hepatobiliary surgical procedures

IMAGING • Normal biliary anatomy ○ Left hepatic duct formed by segmental branches from segments II-IV ○ Right hepatic duct has 2 branches, including a horizontally oriented anterior branch draining segments V and VIII and a vertically oriented posterior branch draining segments VI and VII ○ Right and left hepatic ducts converge at porta hepatis to form common hepatic duct (CHD) • Most common variants ○ Usually aberrant right posterior branch which can drain into left hepatic duct ("crossover anomaly"), CHD, common bile duct (CBD), cystic duct, or gallbladder (GB) ○ Most frequent: Right posterior duct drains into left duct

(Left) Upper left-hand graphic (A) shows the conventional arrangement of the bile ducts. Variations are common, especially with aberrant insertion of the right posterior duct, as seen in figures D-F. This may lead to inadvertent ligation or transection at surgery. (Right) Graphic shows common variations in the course and insertion of the cystic duct, leading to difficulty in isolation and ligation at cholecystectomy. The cystic duct may be mistaken for the common hepatic or common bile duct.

(Left) Intraoperative cholangiogram shows a peculiar bilobed cystic dilation of the distal common duct , presumably a type 3 choledochal cyst or choledochocele. Also noted is aberrant drainage of the posterior lobe bile duct into the common hepatic duct. (Right) Coronal MRCP with MIP reconstruction demonstrates separate origins of the right anterior and posterior ducts from the common duct. MRCP has a very high concordance with ERCP for identifying biliary tree variants.

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○ 2nd most common is right posterior duct fusing with lateral (right) aspect of right anterior duct

TOP DIFFERENTIAL DIAGNOSES • MRCP artifacts may simulate or obscure pathology ○ Reconstruction artifacts (with MIP reconstructions) ○ Respiratory motion artifacts ○ Partial volume effect ○ Overestimation of ductal narrowing ○ Susceptibility artifacts (e.g., surgical clips, coils) ○ Pulsatile vascular compression ○ Intraductal mimics of gallstones (gas, flow artifact) ○ Spasm of sphincter of Oddi

CLINICAL ISSUES • Normal biliary variants are common (42% of population) • No clinical significance unless surgery is planned • Risk of injury if surgeon is unaware (especially anomalies of cystic duct and right hepatic duct)

Biliary Normal Variants and Artifacts

Definitions • Variants and artifacts that may simulate pathology or potentially complicate hepatobiliary surgical procedures

IMAGING General Features • Normal biliary anatomy ○ Right hepatic duct (which is typically relatively short) has 2 branches – Anterior (ventrocranial) branch drains segments VI and VIII and has horizontal course extending lateral and towards right from right hepatic duct – Posterior (dorsocaudal) branch drains segments VI and VII and has vertical course extending upward from right hepatic duct – Right posterior duct fuses to right anterior duct from medial approach ○ Left hepatic duct formed by segmental branches from segments II-IV ○ Bile duct from caudate lobe can join origin of left or right hepatic ducts ○ Right and left hepatic ducts converge at porta hepatis to form common hepatic duct (CHD) ○ Cystic duct usually joins CHD just below confluence of right and left hepatic ducts ○ Only central intrahepatic ducts seen on MRCP in normal patients ( 3 mm): Visualization of too many intrahepatic ducts raises concern for ductal strictures or dilatation • Most common variants ○ Most common anatomic variants involve aberrant right hepatic duct – Usually aberrant posterior branch, which can drain into left hepatic duct ("crossover anomaly"), CHD, common bile duct (CBD), cystic duct, or gallbladder (GB) □ Most frequent is right posterior duct draining into left hepatic duct (13-19% of population) □ 2nd most common variant is right posterior duct fusing with lateral (right) aspect of right anterior duct (~ 12% of population) ○ Abnormal junction of hepatic ducts – Trifurcation pattern ("triple confluence"), with single junction of left hepatic duct with anterior and posterior branches of right hepatic duct (11% of population) □ Right hepatic duct nonexistent in this pattern ○ Accessory hepatic ducts seen in 2% of patients ○ Anomalous insertion of cystic duct – Low insertion into common duct (10% of population) – May insert into right hepatic duct – May insert into medial aspect of common duct – May follow parallel course to CHD over several cm • Uncommon or rare variations ○ Duplication of cystic duct or CBD ○ Agenesis of GB (rare, ± other anomalies in 75%) ○ Duplication of GB (very rare) ○ Cholecystomegaly (enlarged GB) – Acquired anomaly

– Seen in patients with diabetes, sickle cell disease, or pregnancy, as well as after truncal vagotomy ○ Microgallbladder – Acquired, most often in cystic fibrosis patients • Pancreaticobiliary junction variants ○ Separate entrance of CBD and main pancreatic duct into duodenum ○ Long (> 8 mm) common channel of distal CBD and pancreatic duct ○ CBD may enter side of pancreatic duct – > 1.5 cm proximal to ampulla of Vater – Commonly seen in type I choledochal cyst – Associated with higher prevalence of cholangiocarcinoma, gallbladder carcinoma, choledocholithiasis, and chronic pancreatitis • Persistent postoperative dilation of bile ducts ○ Affects common duct more commonly than intrahepatic ducts ○ Common duct > 8 mm in diameter ○ Most common in elderly patients following cholecystectomy ○ Especially common in patients who had choledocholithiasis and dilated common duct prior to surgery – Also seems to occur without precholecystectomy dilation (controversial)

Biliary System

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ ERCP or MRCP – MRCP is noninvasive but more susceptible to artifacts, which can result in misinterpretation

DIFFERENTIAL DIAGNOSIS MRCP Artifacts and Pitfalls • Reconstruction artifacts ○ Frequently a problem with maximum intensity projection (MIP) reconstructions ○ Partial volume averaging may obscure small filling defects (e.g., gallstones or polypoid tumors) ○ Reviewing thin-section source 3D MRCP images rather than MIP reconstructions or thick-slab 2D MRCP increases accuracy in identifying subtle abnormalities • Respiratory motion artifacts ○ More common in 3D thin-section MRCP due to longer acquisition times – Particularly problematic on MIP reconstructions ○ CBD or main pancreatic duct may appear disconnected, stenotic, dilated, or duplicated due to motion artifact ○ Single-shot fast spin echo (SSFSE) images acquired using a much shorter acquisition time and have fewer motion artifacts • Flow artifact ○ Low-signal focus in center of bile duct (rare location for stone) ○ Often within dilated duct (such as at point of cystic duct insertion) due to swirling or helical flow of bile ○ More common when using single-shot fast spin echo sequences (i.e., HASTE) and less common on sequences acquired with T2 FSE or SSFP technique 863

Biliary System

Biliary Normal Variants and Artifacts

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○ Any potential filling defect should be confirmed on multiple sequences Susceptibility artifacts ○ Susceptibility artifact from metallic foreign bodies (such as surgical clips, endovascular coils, stents, etc.) produces adjacent signal loss, potentially mimicking stone or filling defect within biliary tree – New titanium clips do not create susceptibility artifact ○ Gas in stomach and duodenum can cause large signal void, covering middle and lower CBD, mimicking biliary stone or obstruction ○ Careful evaluation of coronal source images and in-phase gradient echo images (which highlight susceptibility artifact) can prevent misdiagnosis Pulsatile vascular compression ○ Pulsatile compression of biliary tree by adjacent artery occurs during systole, causing pseudocalculus defect – Hepatic, cystic, and gastroduodenal arteries traverse biliary tree in their courses – Most commonly seen due to right hepatic artery crossing CHD or left hepatic duct – Can also result from motion of anterior wall of IVC near extrahepatic bile duct ○ Usually a band-like defect in duct without dilatation of upstream biliary tree ○ Most commonly affected sites are CHD, left hepatic duct, and mid CBD Fluid in GI tract ○ Fluid in stomach or duodenum may overlap biliary tree, obscuring biliary lesions ○ Negative oral contrast media (such as ferumoxsil) or routinely acquiring 2D thick-slab MRCP from multiple different angles can help avoid problems Intraductal mimics of gallstones ○ Pneumobilia, hemobilia, and debris have low signal intensity on MRCP, mimicking gallstones – Air-fluid level within duct suggests pneumobilia Spasm of sphincter of Oddi ○ May simulate distal CBD stone ○ Routinely acquiring multiple sequential 2D thick-slab MRCP acquisitions in succession can distinguish true stenosis (which will be unchanged over multiple acquisitions) from temporary spasm (which will open on at least 1 acquisition) Overestimation of ductal narrowing ○ MRCP depicts biliary tree in physiologic state vs. ERCP depiction of biliary tree under supraphysiologic distention Pseudostenosis of pancreatic duct ○ In fasting patients, secretion of pancreas is reduced, and normal pancreatic duct may be collapsed segmentally – No dilatation of upstream pancreatic duct is identified Pseudodilatation of CBD ○ Long cystic duct running parallel to CHD may be confused for common duct ○ Cystic duct and common duct together may appear to represent dilated duct on MIP reconstructions ○ Error can be avoided by reviewing source images (rather than just MIP reconstructions) Iodinated contrast material ○ Low signal intensity on T2WI and not visualized on MRCP

○ Performing MRCP immediately after ERCP may lead to nonvisualization of extrahepatic bile duct and GB • Impacted distal CBD stone ○ Can be missed on MRCP images due to lack of bile around stone ○ Ampulla is known difficult location for MRCP, but axial images or MRCP in different planes may help overcome this pitfall

CLINICAL ISSUES Demographics • Epidemiology ○ Normal biliary variants are common: 42% of population (23% of cholangiograms) ○ Do not correlate with hepatic arterial or portal venous anomalies

Natural History & Prognosis • Usually no clinical significance unless surgery is planned ○ Risk of injury if surgeon is unaware (especially anomalies of cystic duct and right hepatic duct) ○ Aberrant right hepatic duct may disqualify potential right lobe liver donor

DIAGNOSTIC CHECKLIST Consider • MIP reconstructions may obscure small biliary filling defects due to partial volume effect ○ Image interpretation should not be solely based on MIP reconstructions but also on review of thin-section images as well • Pulsation artifact from right hepatic artery may mimic stenosis in CHD or left hepatic duct • Flow artifacts are more common with single-shot fast spinecho sequences and can mimic stone in center of duct ○ Any potential ductal filling defect should be confirmed on other sequences

Image Interpretation Pearls • Careful depiction of biliary anatomy is crucial for planning partial liver transplantation • Pseudocalculi and other artifacts are common in biliary tree, making familiarity with artifacts critical to avoid unnecessary intervention

Reporting Tips • Dilated bile ducts in elderly, post cholecystectomy patient should be correlated with clinical or biochemical evidence of biliary obstruction ○ If neither is present, probably no need for additional imaging evaluation

SELECTED REFERENCES 1. 2.

Ragab A et al: Correlation between 3D-MRCP and intra-operative findings in right liver donors. Hepatobiliary Surg Nutr. 2(1):7-13, 2013 Griffin N et al: Magnetic resonance cholangiopancreatography: the ABC of MRCP. Insights Imaging. 3(1):11-21, 2012

Biliary Normal Variants and Artifacts Biliary System

(Left) Intraoperative cholangiogram obtained prior to right lobe liver donation shows insertion of the right posterior duct into the proximal left bile duct . (Right) Coronal MRCP with MIP reconstruction demonstrates the right posterior duct arising from the left hepatic duct. This is the most common biliary anatomic variant, and is found in 13-19% of the population.

(Left) Coronal 3D reconstruction CT cholangiogram of a potential liver donor shows trifurcation of the common duct into left , right anterior , and right posterior ducts. This anatomy may require more complex biliary reconstruction during transplantation or may preclude donation. (Right) Axial T2WI shows a small signal void in the middle of the distal common duct . There was no proximal ductal dilation. Flow artifacts like these are more common when using single-shot technique.

(Left) Coronal MRCP shows a signal void in the common hepatic duct that simulates a stone. Note the absence of dilation of the ducts upstream from this point. (Right) MR cholangiogram performed after administration of Eovist in a potential right lobe liver donor shows drainage of the right posterior duct into the proximal left hepatic duct. Note the pulsation artifact proximal to the bifurcation and a motion-reconstruction artifact along the mid common duct .

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Biliary System

Congenital Abnormalities of the Gallbladder KEY FACTS

TERMINOLOGY • Spectrum of congenital malformations of gallbladder (GB) shape, morphology, number, or position ○ Agenesis of GB: Congenital absence of GB ○ Hypogenesis of GB: Rudimentary or atretic GB ○ Bilobed GB: 2 completely divided GB cavities with a common cystic duct ○ Duplicated GB: Duplicated GB with separate cystic ducts for each moiety ○ Multiseptate GB: Single GB with "honeycomb" appearance due to innumerable internal septations ○ Hourglass GB: Hourglass shape of GB may be congenital or acquired due to chronic inflammation ○ Congenital diverticulum: Usually true diverticulum that can be seen anywhere in GB ○ Phrygian cap: Folding of GB fundus (considered normal variant given its high prevalence) ○ Ectopic GB: Ectopically positioned GB has been reported in nearly every possible position in abdomen and pelvis

(Left) Ultrasound demonstrates the characteristic appearance of a phrygian cap, with a fold near the gallbladder (GB) fundus. This is considered a normal variant given its high prevalence. (Right) Axial T2WI FSE MR in a woman with chronic abdominal pain shows an incidental phrygian cap .

(Left) Ultrasound demonstrates many septations within the GB, creating a "honeycomb" appearance, characteristic of a multiseptate GB. (Right) Coronal Tc-99m HIDA scan of a 54-year-old woman with abdominal pain shows progressive filling of the bile duct and proximal small bowel , but no GB activity. The patient had no operative history and multiple imaging studies confirmed GB agenesis.

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– Most common ectopic positions are intrahepatic, under left hepatic lobe, transverse, and retrohepatic – Surgical removal of intrahepatic GB may be challenging ○ Floating or wandering GB: Mobile GB due to long mesentery, completely covered by peritoneum – High risk of GB torsion and gangrenous inflammation

TOP DIFFERENTIAL DIAGNOSES • • • • •

Prior cholecystectomy Chronic cholecystitis Hartmann pouch of GB Hyperplastic cholecystoses Abdominal fluid collection

CLINICAL ISSUES • Virtually always incidental finding of no clinical significance • Floating or wandering GB has higher likelihood of torsion due to increased risk of GB "twisting" on long pedicle

Congenital Abnormalities of the Gallbladder

IMAGING

Synonyms

CT Findings

• Gallbladder malformation

• GB agenesis: Absence of GB in patient with no history of prior cholecystectomy; should exclude prior history of cholecystectomy or ectopic position of GB before arriving at this diagnosis • Bilobed GB: External contour of GB may be normal and division between duplicated GB cavities may be imperceptible ○ Prominent GB fold or phrygian cap may be a mimic • Duplicated GB: External contour of GB may or may not be normal; separate cystic ducts and cystic arteries leading to 2 separate GBs in close contiguity ○ Easiest to distinguish 2 GBs if there is sludge, cholelithiasis, or vicariously excreted contrast in 1 GB but not the other • Multiseptate GB: Innumerable septations within single GB with normal external contour resulting in "honeycomb" appearance • Phrygian cap: Prominent folding of GB fundus on GB body

Definitions • Spectrum of congenital malformations of gallbladder (GB) shape, morphology, number, or position ○ Agenesis of GB: Congenital absence of GB ○ Hypogenesis of GB: Rudimentary or atretic GB – Differentiate from acquired microgallbladder in cystic fibrosis due to viscous bile or chronic cholecystitis ○ Bilobed GB: 2 completely divided GB cavities with a single common cystic duct – Differentiate from cholecystomegaly (abnormally large GB) in sickle cell disease, pregnancy, or obesity ○ Duplicated GB: Duplicated GBs with separate cystic ducts for each moiety – Cystic ducts may separately insert into extrahepatic bile duct (H-type) or have common insertion (Y-type) – Each gallbladder has a separate cystic artery ○ Triplicate GB (vesica fellea triplex): 3 separated GB ○ Multiseptate GB: Single GB with "honeycomb" appearance due to innumerable internal septations, likely due to incomplete vacuolization of developing GB bud ○ Hourglass GB: Hourglass shape of GB may be due to abnormal vacuolization – In adults, may be acquired abnormality (due to chronic inflammation and scarring) ○ Congenital diverticulum: Usually a true diverticulum (containing all layers of GB wall) that can be located anywhere in GB – Differentiate from acquired diverticula due to prior cholecystitis or traction from prior surgery or duodenitis ○ Phrygian cap: Folding of GB fundus that is considered normal variant given its high prevalence – Most common variant of GB shape ○ Ectopic GB: Ectopically positioned GB has been reported in nearly every possible position in abdomen and pelvis – Most common positions are intrahepatic, under left hepatic lobe, transverse, retrohepatic, and retroperitoneal ○ Left-sided GB: Ectopic GB positioned in left side of abdomen – Isolated or associated with situs inversus – Cystic duct usually inserts into left hepatic duct – May be associated with left portal vein anomalies ○ Intrahepatic GB: Subcapsular GB partially or completely embedded in liver ○ Horizontal GB: Ectopic GB within porta hepatis; usually deeply embedded in liver ○ Retrodisplaced GB: Retrohepatic or retroperitoneal ectopic GB ○ Floating or wandering GB: Mobile GB due to long mesentery, completely covered by peritoneum – May be positioned throughout abdomen – High risk of GB torsion and may cause pain by herniating through foramen of Winslow into lesser sac

Biliary System

TERMINOLOGY

MR Findings • MRCP helpful for demonstrating anatomy of cystic ducts to differentiate bilobed GB from duplicated GB ○ May also provide better soft tissue resolution to identify internal septations or compartments • Delayed gadoxetate (Eovist) enhanced images may show communication between lumina and can delineate cystic duct anatomy

Ultrasonographic Findings • Grayscale ultrasound ○ First-line modality for evaluation of GB pathologies and anomalies

Nuclear Medicine Findings • Hepatobiliary scintigraphy ○ Absent GB activity may prompt erroneous diagnosis of cystic duct obstruction and acute cholecystitis ○ Intrahepatic GB appears as focal photopenic defect on early phase

Imaging Recommendations • Best imaging tool ○ Ultrasound as screening tool (usually incidental imaging finding on US performed for other reasons) ○ MR for confirmation and better definition of abnormalities

DIFFERENTIAL DIAGNOSIS Prior Cholecystectomy • Most common cause of absent GB

Chronic Cholecystitis • Much more common than congenital anomalies • Scarring due to chronic cholecystitis can result in shrinkage of GB (mimicking GB hypogenesis) or hourglassshaped/multiseptate GB • Usually associated with cholelithiasis

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Biliary System

Congenital Abnormalities of the Gallbladder

Hartmann Pouch of GB • Acquired diverticulum along inferior aspect of GB neck/infundibulum • Associated with chronic obstruction and cholelithiasis • GB diverticula can also be acquired due to traction from prior surgery or adjacent duodenal inflammation

Hyperplastic Cholecystoses • Prominent Rokitansky-Aschoff sinuses in GB adenomyomatosis can mimic diverticulum • Focal mass-like adenomyomatosis at fundus can mimic bilobed GB, duplicated GB, or phrygian cap • Configuration and presence of wall thickening (and "comet tail" artifact) are helpful to distinguish 2 entities

Abdominal Fluid Collection • Intraabdominal fluid collections can mimic ectopic GB • Ectopic GB is continuous with biliary tree (best evaluated on CT, MRCP, and cholangiography) • Patient's history and history of prior cholecystectomy are helpful

PATHOLOGY General Features • Etiology ○ Abnormal development resulting in absence, abnormal formation, or deformity of GB ○ Genetic and environmental factors play a role • Associated abnormalities ○ Agenesis of GB has high association with biliary atresia and other congenital malformations • Normal embryology ○ GB arises from hepatic diverticulum (ventral bud) of caudal primitive foregut during week 4 of intrauterine life – Hepatic diverticulum further divides into pars hepatica (developing into liver and intrahepatic ducts) and pars cystica (developing into GB and extrahepatic bile ducts) ○ GB starts as solid cord that vacuolizes by 8th week of intrauterine life • Pathogeneses ○ Abnormal formation (agenesis, hypogenesis, duplication, triplication) ○ Abnormal vacuolization (bilobed GB, hourglass/multiseptate GB, congenital stricture or atresia of cystic duct) ○ Abnormal migration of ventral bud (GB ectopia) ○ Deformity (folds, phrygian cap, hourglass GB) ○ Heterotopia and choristoma (ectopic tissue of endodermal origin such as hepatic, gastric, adrenal, thyroid, or pancreatic tissue in GB wall)

Staging, Grading, & Classification • Abnormal formation ○ Hypogenesis (rudimentary GB) ○ Phrygian cap ○ Hourglass/multiseptate GB ○ Bilobed GB ○ Gallbladder diverticulum • Abnormal number 868

○ Agenesis ○ Duplicated GB ○ Triplicate GB • Ectopia (abnormal position) ○ Intrahepatic GB ○ "Floating" GB ○ Left-sided GB ○ Transverse GB ○ Retrodisplaced GB

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic: Virtually always an incidental finding • Other signs/symptoms ○ RUQ pain due to biliary colic and inflammation ○ Inflammation of 1 moiety in a duplicated or bilobed GB in cholecystitis may cause clinical confusion

Demographics • Epidemiology ○ Phrygian cap is normal variant seen in up to 6% of normal population ○ Other congenital anomalies are rare – Agenesis of GB prevalence: 0.04-0.13% in autopsy series – Duplicated GB prevalence: 1-5 per 10,000 ○ Given their rarity, exact prevalence and gender distribution are not well studied

Natural History & Prognosis • Virtually always of no clinical significance • Very rarely may predispose to biliary stasis, inflammation, and stone formation • "Floating" or "wandering" GB has higher likelihood of torsion due to risk of GB "twisting" on long vascular pedicle ○ Usually diagnosed as acute cholecystitis on imaging ○ risk of gangrene compared to traditional cholecystitis

Treatment • No treatment or follow-up in asymptomatic patients • Cholecystectomy if symptomatic due to cholelithiasis, cholecystitis, or torsion ○ Surgical removal of intrahepatic GB may be challenging

DIAGNOSTIC CHECKLIST Consider • Ectopic location or agenesis if GB is not visualized

Reporting Tips • Congenital anomalies may impact surgical planning for cholecystectomy

SELECTED REFERENCES 1.

Revzin MV et al: The gallbladder: uncommon gallbladder conditions and unusual presentations of the common gallbladder pathological processes. Abdom Imaging. Epub ahead of print, 2014

Congenital Abnormalities of the Gallbladder Biliary System

(Left) Ultrasound demonstrates 2 cystic structures in the GB fossa, one of which contains anechoic bile and the other containing sludge . (Right) Axial T2 FS MR in the same patient demonstrates the 2 cystic structures seen on US, one showing high T2 signal , and the other showing intermediate to high T2 signal . Two separate cystic ducts were seen on MRCP (not shown), allowing the diagnosis of a duplicated GB (rather than a bilobed GB).

(Left) Ultrasound of an elderly debilitated man with right upper quadrant pain shows dependent sludge within both lobes of a bilobed GB. (Right) CECT of the same patient shows 2 separate GBs . Both lobes of a bilobed GB share a common cystic duct. Persistent abdominal pain and leukocytosis prompted cholecystostomy drainage of the more superficial GB. Both lumina were successfully decompressed.

(Left) Transverse ultrasound of a neonate shows a completely intrahepatic GB . As an isolated finding this is not clinically significant, although the location of the GB may make cholecystectomy exceedingly difficult. (Right) Coronal MRCP shows a cystic structure adjacent to the GB. The configuration of the "cyst" is characteristic of GB duplication. Both the GB and the "cyst" are partially opacified via separate cystic ducts on a follow-up Eovist enhanced MRCP.

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Biliary System

Caroli Disease KEY FACTS

TERMINOLOGY • Caroli disease: Congenital multifocal saccular dilation of large intrahepatic bile ducts in absence of other hepatic abnormalities • Caroli syndrome: More common variant characterized by saccular dilatation of intrahepatic ducts, hepatic fibrosis, and portal hypertension

IMAGING • CECT:Multiple nonenhancing cysts of varying size that communicate with biliary tree ○ Variably distributed (diffuse, lobar, or segmental) ○ Enhancing "dot" (portal radicles) at either center or periphery of dilated duct: Central dot sign on CECT ○ Hepatolithiasis frequent • MR: T1 hypointense, T2 hyperintense, nonenhancing cysts variably distributed in liver ○ Communication with biliary tree well visualized on MRCP ○ Central dot sign visible on T1WI C+

(Left) Gross photograph of the liver shows clusters of dilated and cystic intrahepatic bile ducts in a patient with Caroli disease. (Courtesy J. Misdraji, MD.) (Right) Frontal ERCP shows saccular dilatation of the large intrahepatic ducts as well as multiple ductal filling defects, representing biliary calculi , a characteristic constellation of findings in Caroli disease.

(Left) Axial T2WI MR shows gross, irregular dilation of the intrahepatic bile ducts . (Right) Coronal MRCP in the same patient makes it easier to recognize the continuity of the cystic intrahepatic lesions with the biliary tree, compatible with Caroli disease. The gallbladder is also seen . This patient was treated with liver transplantation.

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○ Hepatolithiasis: Signal voids within dilated ducts • ERCP: Dilatation (usually saccular) of large intrahepatic ducts with alternating biliary strictures

PATHOLOGY • Pathogenesis not completely understood but likely due to arrest or derangement in remodeling of ductal plate ○ Considered to be variant of fibropolycystic liver disease ○ Typically autosomal recessive inheritance • Frequently associated with polycystic hepatorenal syndrome (usually autosomal recessive), hepatic fibrosis, and medullary sponge kidney • Presentation in childhood or young adulthood often due to cholangitis, cholestasis, or progressive hepatic fibrosis

CLINICAL ISSUES • Supportive therapy (antibiotics, sphincterotomy, stone removal) for cholangitis and stone disease • Surgery, including partial hepatectomy or liver transplant, may be option depending on distribution of involvement

Caroli Disease

Definitions • Originally divided into 2 variants ○ Caroli disease ("pure" form): Congenital multifocal saccular dilation of large intrahepatic bile ducts (IHBDs) in absence of other hepatic abnormalities ○ Caroli syndrome ("complex" form): More common variant characterized by cystic dilatation of large intrahepatic ducts, hepatic fibrosis, and portal hypertension

IMAGING General Features • Best diagnostic clue ○ Multiple intrahepatic cysts of varying size that communicate with biliary tree ○ Central dot sign: Enhancing tiny dots (portal radicles) within dilated intrahepatic bile ducts on CECT • Location ○ Saccular dilatation of intrahepatic ducts can be diffuse, lobar, or segmental – Caroli syndrome usually involves entire liver diffusely – Caroli disease occasionally can be lobar (usually left lobe) but usually predominates in 1 segment □ Number of cysts usually < 10 in cases with lobar distribution • Size ○ Cysts can be of variable size (mm to cm) • Morphology ○ Segmental saccular dilatation of large intrahepatic bile ducts separated by normal or dilated bile ducts – Individual cysts are contiguous with biliary tree ○ Size of common bile duct (CBD) is classically thought to be normal – Extrahepatic duct may be dilated in up to 50%, possibly due to prior cholangitis, passage of stones, or concurrent choledochal cyst • Considered to be a variant of fibropolycystic liver disease ○ Other variants include congenital hepatic fibrosis, autosomal dominant (ADPKD) and recessive (ARPKD) polycystic liver and kidney disease, biliary hamartomas, and choledochal cyst • Todani classification of choledochal cysts ○ Caroli disease is classified as type V choledochal cyst: Cystic dilation of intrahepatic bile ducts

Radiographic Findings • Endoscopic retrograde cholangiopancreatogram (ERCP) ○ Dilatation (saccular more often than fusiform) of large intrahepatic ducts (either diffuse, lobar, or segmental) with alternating sites of bile duct strictures/narrowing ○ Hepatolithiasis and sludge are common and appear as filling defects ○ In cases with cholangitis, ERCP may demonstrate communication of biliary tree with biliary abscesses

CT Findings • Nonenhancing cysts of varying size that communicate with biliary tree ○ Variably distributed (diffuse, lobar, or segmental)

• Enhancing portal radicles surrounded by saccular dilated ducts yields central dot sign on CECT ○ Enhancing "dot" can be either at center or periphery of dilated duct • Hyperdense hepatolithiasis may be easier to perceive on NECT • Other findings related to concurrent hepatic fibrosis ○ Hypertrophic lateral segment, atrophic right lobe (similar to other causes of cirrhosis) ○ Normal or hypertrophied medial segment (distinct feature not usually seen in other causes of cirrhosis) • Other findings related to frequently associated renal abnormalities ○ Findings of ARPKD, ADPKD, medullary sponge kidney, medullary cystic disease

Biliary System

TERMINOLOGY

MR Findings • T1 hypointense, T2 hyperintense, nonenhancing cysts variably distributed in liver ○ Communication with biliary tree most evident on MRCP ○ Due to communication with biliary tree, cysts fill with contrast in hepatobiliary phase when using hepatobiliary contrast agent (e.g., gadoxetate [Eovist]) ○ Central dot sign visible on T1WI C+: Enhancement of portal radicles within dilated IHBD – Portal radicles may appear as signal void at center of dilated ducts on T2W or MRCP images ○ Hepatolithiasis appears as nonenhancing signal voids within dilated ducts

Ultrasonographic Findings • Dilated intrahepatic bile ducts: Communication between cysts and biliary tree may be difficult to demonstrate on US • Echogenic septa may completely or incompletely traverse dilated lumen of bile ducts (intraductal bridging sign) • Small portal venous branches may be partially or completely surrounded by dilated IHBD (US correlate of central dot sign • Intraductal calculi common and appear as echogenic nodules with dense posterior acoustic shadowing

Imaging Recommendations • Best imaging tool ○ MRCP

DIFFERENTIAL DIAGNOSIS AD Polycystic Hepatic Disease • Numerous (> 10 but usually hundreds) hepatic cysts • No biliary dilatation or communication between cysts and biliary tree ○ Cysts do not opacify on cholangiography • Frequent association with renal cysts

Biliary Hamartomas • Ductal plate malformation involving small-sized intrahepatic ducts (variant of fibropolycystic disease) • Innumerable subcentimeter nodules in liver, which can be completely cystic or have solid components which enhance and become isodense with liver • Biliary hamartomas do not communicate with biliary tree

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Biliary System

Caroli Disease

Primary Sclerosing Cholangitis • Strictures of intra- and extrahepatic bile ducts with alternating strictures, normal ducts, and dilated ducts • Ductal dilatation much less severe compared to Caroli disease, and dilated ducts do not appear saccular • Often progresses to cirrhosis and liver failure

Ascending Cholangitis • Infection of biliary tree secondary to biliary obstruction (usually due to choledocholithiasis) • May result in development of intrahepatic biliary abscesses that communicate with bile ducts • Unlike Caroli disease, margins of abscesses are thick and irregular with surrounding parenchymal edema

Recurrent Pyogenic Cholangitis • Disease characterized by formation of pigment stones throughout biliary tree, with resultant biliary strictures and repeated bouts of cholangitis ○ Biliary calculi may be cast-like and expand ductal lumen • Dilatation of both intra- and extrahepatic bile ducts, usually of cylindrical morphology (not saccular) • Almost always in patients from southeast Asia, and may be associated with parasitic and bacterial biliary infections

PATHOLOGY General Features • Etiology ○ Pathogenesis not completely understood, but likely due to arrest or derangement in remodeling of ductal plate – Caroli disease: Malformation of large-sized ducts – Caroli syndrome: Malformation of large and smallsized ducts □ Ductal plate anomaly of small-sized ducts is responsible for hepatic fibrosis • Genetics ○ Typically autosomal recessive inheritance (rare instances of autosomal dominant inheritance reported) ○ Believed to be caused by mutation in PKHD1 (polycystic kidney and hepatic disease) gene on chromosome 6 (encoding fibrocystin) – Same genetic basis as ARPKD, but different manifestation of same genetic disease • Associated abnormalities ○ Medullary sponge kidney and renal fibrosis ○ Autosomal recessive polycystic liver and kidney disease (rarely associated with ADKPD) ○ Hepatic fibrosis, hepatic cysts, biliary hamartomas ○ Choledochal cysts

CLINICAL ISSUES

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– Biliary obstruction may result in symptoms of cholestasis (jaundice, pruritus, etc.) ○ Caroli syndrome may present with symptoms related to hepatic fibrosis (i.e., portal hypertension) • Diagnosis is almost always based on imaging findings (especially MRCP and ERCP), and biopsy is not typically indicated

Demographics • Age ○ Condition is present at birth, although patients can be asymptomatic for years – 80% become symptomatic before age of 30 ○ Caroli disease: Symptoms usually by 2nd/3rd decades ○ Caroli syndrome: Symptoms can present during infancy or childhood – Concurrent renal anomalies present early in life • Gender ○ M:F = 1:1

Natural History & Prognosis • Complications ○ Recurrent bouts of cholangitis ± hepatic abscesses – Biliary dilatation stagnation of bile intraductal sludge/stone formation cholangitis ○ Stone formation (95%) (usually calcium bilirubinate) ○ Secondary biliary cirrhosis ± portal hypertension ○ Cholangiocarcinoma (up to 7% risk) • Prognosis ○ Depends on severity of disease and coexisting renal disease ○ Long-term prognosis for Caroli disease is usually poor

Treatment • Supportive therapy for cholangitis/sepsis and stone disease ○ Antibiotics for cholangitis ○ Sphincterotomy/stone extraction for extrahepatic stones ○ Intrahepatic stones may be treated with lithotripsy ○ Oral bile salts may be an option, especially for intractable intrahepatic stones (e.g., ursodeoxycholic acid [UDCA]) • Decompression of biliary tract can be performed via external drainage or biliary-enteric anastomosis • Surgery is an option in select patients ○ Hepatic lobectomy or segmentectomy possible if dilated ducts confined to lobe or segment ○ Liver transplantation possible for diffuse involvement of entire liver – Comparable results to liver transplantation for other indications

DIAGNOSTIC CHECKLIST

Presentation

Consider

• Most common signs/symptoms ○ Usually asymptomatic in early stage, but often symptomatic in childhood or early adulthood ○ Patients with both Caroli syndrome and Caroli disease may experience symptoms related to biliary disease, most often fever and abdominal pain due to recurrent bouts of cholangitis

• Distinguish Caroli disease from other liver diseases that are associated with either hepatic cysts or dilated bile ducts

SELECTED REFERENCES 1.

Zhang DY et al: Caroli's disease: a report of 14 patients and review of the literature. J Dig Dis. 13(9):491-5, 2012

Caroli Disease Biliary System

(Left) Axial CECT shows massive dilatation of the intrahepatic bile ducts. Note the "central" or "eccentric" dot within many of the cystic structures, representing portal radicles , a classic imaging finding in Caroli disease. (Right) Axial CECT shows Caroli syndrome in a 40-yearold woman with hepatic and renal failure. Note the cystic dilations of the bile ducts and central dot sign . Hepatic and renal fibrosis was the cause of liver and renal failure and portal hypertension in this patient.

(Left) Color Doppler ultrasound of a patient with Caroli disease shows saccular dilatation of the branches of the left bile duct . Note eccentric color Doppler "dot" within the medial segmental branch of the left duct , similar to the central dot sign more commonly described on CT or MR. (Right) Axial T2WI MR shows saccular dilatation of the intrahepatic bile ducts, many of which contain large hypointense calculi .

(Left) Coronal T2 MR demonstrates multiple cysts predominantly in the right hepatic lobe which communicate with the biliary tree, compatible with Caroli syndrome. (Right) Coronal CECT in the same patient again demonstrates saccular dilatation of multiple ducts in the right hepatic lobe. Note the diffusely low attenuation of the parenchyma in the involved portions of the liver, likely on the basis of hepatic fibrosis and edema from cholangitis.

873

Biliary System

Choledochal Cyst KEY FACTS

TERMINOLOGY • Congenital segmental cystic dilatation of intrahepatic or extrahepatic bile ducts, most commonly affecting main portion of extrahepatic duct (ED)

IMAGING

PATHOLOGY

• Segmental cystic dilatation of bile ducts with dilated segments maintaining communication with biliary tree ○ Diagnosis requires excluding other causes of biliary dilatation, including tumor, stone, or stricture ○ Commonly associated with cholelithiasis, cystolithiasis, choledocholithiasis, and hepatolithiasis • Classified into 5 types based on Todani classification ○ Type I: Fusiform/cystic dilation of extrahepatic duct ○ Type II: True diverticulum of supraduodenal ED ○ Type III: Dilation limited to intraduodenal segment of ED (a.k.a. choledochocele), with dilated segment of duct located within duodenal wall

• Etiology may be related to anomalous pancreaticobiliary junction or congenital ductal plate malformation

(Left) This graphic shows the Todani classification of choledochal cysts. Note that type I is fusiform dilation of the extrahepatic duct (ED). Type II is a true diverticulum of the supraduodenal ED. Type III is an isolated choledochocele. Type IV is fusiform dilation of the extrahepatic duct and intrahepatic ducts, and type V is synonymous with Caroli disease. (Right) Coronal CECT reformation of a type I choledochal cyst shows fusiform dilatation of the extrahepatic duct . Type I lesions are the most common type of choledochal cyst.

(Left) Curved multiplanar CECT reformation along the length of the extrahepatic duct shows a small choledochocele protruding into the duodenal lumen and mild dilation of the common bile duct . This is either a type III or IVb choledochal cyst, depending on whether the ED is considered to be involved. (Right) Coronal MRCP in the same patient nicely shows the choledochocele protruding into the duodenal lumen and the mildly dilated extrahepatic duct , along with numerous stones in the gallbladder .

874

○ Type IV: Presence of multiple biliary cysts, at least 1 of which must involve extrahepatic bile duct ○ Type V: Single or multiple intrahepatic biliary cysts, with multiple intrahepatic cysts known as Caroli disease

CLINICAL ISSUES • Most common in female patients, often of Asian descent • Usually diagnosed in infancy and childhood • Classic triad of symptoms: Recurrent RUQ pain, jaundice, and palpable mass • Complications: Stones, cholangitis, pancreatitis, or malignant degeneration (cholangiocarcinoma or gallbladder cancer) • Treatment varies depending on type of choledochal cyst, but type I and IV cysts typically undergo surgical excision and reconstruction by Roux-en-Y hepaticojejunostomy

Choledochal Cyst

Synonyms • Biliary cyst

Definitions • Congenital segmental cystic dilatation of intrahepatic or extrahepatic bile ducts, most commonly affecting main portion of extrahepatic duct (ED)

IMAGING General Features • Segmental cystic dilatation of bile ducts with dilated segments maintaining communication with biliary tree ○ Diagnosis requires excluding other causes of biliary dilatation, including tumor, stone, or stricture ○ Commonly associated with cholelithiasis, cystolithiasis (stones within choledochal cyst), choledocholithiasis, and hepatolithiasis ○ Most commonly classified into 5 different types based on Todani classification – Type I: Solitary fusiform or cystic dilation of extrahepatic bile duct (ED) □ Type Ia: Cystic dilation of entire ED; associated with abnormal pancreaticobiliary junction (APBJ) □ Type Ib: Focal dilation of ED (often distal); no association with APBJ □ Type Ic: Fusiform dilation of entire ED; associated with APBJ □ Most common type, constituting 50-85% of choledochal cysts □ Differentiate from distal obstruction of ED (e.g., stone or tumor) or mild normal dilatation of ED after cholecystectomy □ Mild dilation of right and left ducts may blur distinction with type IVa – Type II: True diverticulum of supraduodenal ED □ Very rare, accounting for only 2% of cases – Type III: Dilation limited to intraduodenal segment of ED (a.k.a. choledochocele), with dilated segment of ED located within duodenal wall □ Type IIIa: Cystic dilation of intraduodenal ED □ Type IIIb: Diverticulum of intraduodenal ED □ Constitutes 1-5% of cases □ Cyst may be lined by either duodenal or biliary epithelium □ Large choledochoceles may obstruct duodenum, present with jaundice, or cause pancreatitis – Type IV: Presence of multiple biliary cysts, at least 1 of which must involve extrahepatic bile duct □ IVa: Involvement of both intrahepatic and extrahepatic ducts; 2nd most common overall, comprising 40% of cases diagnosed in adults □ IVb: Multiple extrahepatic cysts with no intrahepatic cysts – Type V: Single or multiple intrahepatic biliary cysts, with presence of multiple intrahepatic cysts known as Caroli disease □ No involvement of extrahepatic duct

Radiographic Findings • ERCP: Considered gold standard modality for diagnosis of choledochal cysts ○ Accurate means of evaluating pancreaticobiliary junction ○ May have trouble delineating some portions of biliary tree in cases with coexistent strictures

Biliary System

TERMINOLOGY

CT Findings • Nonenhancing cystic structure (types I, II, or IV) in porta hepatis contiguous with biliary tree ○ Multiplanar images critical for establishing contiguity of cyst with biliary tree • Cystic intramural mass within wall of proximal duodenum communicating with CBD (type III) • Multiple intrahepatic cysts in close contiguity with intrahepatic bile ducts (type IV)

MR Findings • Best noninvasive modality for assessing biliary tree, choledochal cysts, and anomalous pancreaticobiliary junction • MRCP images nicely demonstrate cystic dilatation of biliary tree and relationship (and communication) of cysts with adjacent bile ducts • Choledochal cysts should mirror signal intensity of normal bile ducts (hypointense on T1WI, hyperintense on T2WI, and no perceptible wall enhancement on T1WI C+) • Presence of abnormal wall hyperenhancement or thickening should raise concern for superinfection or malignancy (particularly with nodular or irregular wall thickening)

Ultrasonographic Findings • Grayscale ultrasound ○ Anechoic lesion in porta hepatis (types I, II, or IV) with posterior acoustic enhancement – Can be confused with gallbladder or mesenteric cyst, unless communication with extrahepatic bile duct is established – Gallstones may be present within cyst (with posterior acoustic shadowing) ○ Multiple intrahepatic cysts (type IV or V) with acoustic enhancement – Communication with biliary tree may be difficult to establish for intrahepatic cysts using ultrasound

Nuclear Medicine Findings • Hepatobiliary (HIDA) scan ○ Photopenic area in liver or porta hepatis that shows late filling and prolonged retention (often > 24 hours) of radiotracer ○ Presence of radiotracer within cyst definitely identifies structure as communicating with biliary tree

DIFFERENTIAL DIAGNOSIS Malignant Common Bile Duct (CBD) Obstruction • Often secondary to pancreatic adenocarcinoma, ampullary carcinoma, or distal CBD cholangiocarcinoma • Dilatation of bile ducts proximal to obstruction, with pancreatic duct also dilated with most pancreatic and ampullary tumors 875

Biliary System

Choledochal Cyst

• Abrupt, irregular narrowing of distal CBD differentiates tumor from choledochal cyst

Primary Sclerosing Cholangitis • Idiopathic inflammatory condition leading to progressive fibrosis and strictures of intra- and extrahepatic bile ducts • Multifocal "beaded" strictures with alternating sites of stricture, dilatation, and normal-sized ducts • Bile duct wall may be thickened and hyperenhancing in setting of acute inflammation • "Beading" and irregularity of ducts (with only minimal ductal dilatation) distinct from cystic or fusiform dilatation of choledochal cysts

Recurrent Pyogenic Cholangitis • Formation of pigment stones throughout biliary tree (both intrahepatic and extrahepatic) with multiple biliary strictures, recurrent bouts of cholangitis, and dilatation of both intrahepatic and extrahepatic bile ducts • Disproportionate dilatation of extrahepatic and central intrahepatic ducts, but may cause localized intrahepatic biliary dilatation (often in left lobe) ○ Cylindrical morphology of dilated ducts with intervening strictures (unlike cystic dilatation of choledochal cysts) • Inhabitants or immigrants from southeast Asia

Pancreatic Pseudocyst or Pancreatic Cystic Neoplasm • May abut duodenum or CBD and mimic type II or III cyst

Duodenal Diverticulum • Diverticulum from 2nd/3rd portions of duodenum should be differentiated from type III choledochal cysts, which arise within duodenal wall and directly communicate with CBD

Simple Hepatic Cysts • Do not communicate with biliary tree (unlike type IV or V choledochal cysts with intrahepatic involvement)

PATHOLOGY General Features • Etiology ○ No consensus on etiology, but several hypotheses – Congenital ductal plate malformation – Anomalous junction of CBD and pancreatic duct proximal to duodenal papilla forming long common channel □ Free reflux of enzymes into CBD causes weakening of CBD wall and subsequent dilatation □ 60-90% of patients with choledochal cysts (especially type I and IV) have anomalous pancreaticobiliary junction – Increased pressure in biliary tree due to webs or sphincter of Oddi dysfunction • Associated abnormalities ○ Biliary anomalies, including biliary atresia (usually of distal biliary tree) or stenosis ○ Other forms of fibropolycystic disease, including congenital hepatic fibrosis and biliary hamartomas

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Classic triad of symptoms (most common in children): Recurrent RUQ pain, jaundice, and palpable mass

Demographics • Age ○ Can present from birth to old age, but usually diagnosed in infancy and childhood – 80% are diagnosed in childhood; of these, 25% are detected before age 1, and 60% present before age 10 • Gender ○ M:F = 1:4 • Epidemiology ○ Prevalence: 1:13,000 admissions and 1:150,000 people ○ Strong predominance in Asian populations

Natural History & Prognosis • Complications ○ Stone formation most common complication (within cyst itself, gallbladder, intrahepatic ducts, or pancreatic duct) ○ Recurrent cholangitis or cholecystitis ○ Recurrent or chronic pancreatitis (possibly due to anomalous pancreaticobiliary junction) ○ Large cysts may rupture (extremely rare and reported only in infants) and cause bile peritonitis ○ Secondary biliary cirrhosis due to long-standing biliary obstruction or repeated bouts of cholangitis ○ Malignant degeneration: Most commonly cholangiocarcinoma or gallbladder cancer – True risk of malignancy unknown, but increased risk primarily with type I or IV cysts □ Incidence of malignancy reported as 10-30% with increased risk in older patients – Increased risk of malignancy possibly attributable to pancreaticobiliary reflux secondary to APBJ – Risk persists in intrahepatic ducts even if extrahepatic choledochal cyst has been resected, necessitating long-term surveillance

Treatment • Treatment varies depending on type of choledochal cyst ○ Type I and IV cysts: Surgical excision and reconstruction by Roux-en-Y hepaticojejunostomy due to risk of malignancy and complications (e.g., stones, cholangitis) ○ Type II cysts: Surgical excision of diverticulum ○ Type III cysts: May or may not be treated in asymptomatic patients due to perceived lower risk of malignancy – Symptomatic choledochoceles often treated with endoscopic resection ○ Choledochal cysts with intrahepatic involvement (types IV or V): Conservative management with possible need for liver transplantation in some patients

SELECTED REFERENCES 1.

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Law R et al: Diagnosis and treatment of choledochoceles. Clin Gastroenterol Hepatol. 12(2):196-203, 2014

Choledochal Cyst Biliary System

(Left) Coronal volumerendered CECT in a newborn demonstrates massive dilatation of the extrahepatic duct , with a lesser degree of dilatation of the intrahepatic ducts , compatible with a type IVa choledochal cyst. (Right) Coronal MRCP MIP reconstruction in a young child nicely demonstrates massive dilatation of the extrahepatic duct , as well as focal cystic dilatation of the left hepatic duct , compatible with a type IVa choledochal cyst.

(Left) Coronal MRCP shows massive dilation of the intrahepatic and proximal extrahepatic bile ducts with a sudden transition to a normal distal bile duct . This is a type IVa choledochal cyst. (Right) Ultrasound image demonstrates a cystic mass with internal debris arising in the porta hepatis. Note that the cyst communicates with mildly dilated intrahepatic ducts , compatible with a choledochal cyst (probably type IVa).

(Left) Axial CECT shows a huge laminated stone within a type IV choledochal cyst, with marked dilation of the intrahepatic and extrahepatic ducts (better seen on other sections). (Right) Axial CECT in the same patient shows an enhancing mass arising from the wall of the choledochal cyst. Both stones and cholangiocarcinoma are recognized complications of longstanding choledochal cysts.

877

Biliary System

Recurrent Pyogenic Cholangitis KEY FACTS

TERMINOLOGY • Disease characterized by formation of pigment stones throughout biliary tree, with resultant biliary strictures and repeated bouts of cholangitis

IMAGING

PATHOLOGY

• CT and MR Findings ○ Dilatation of intrahepatic and extrahepatic biliary ducts – Disproportionate dilatation of extrahepatic and central intrahepatic bile ducts – Localized intrahepatic biliary ductal dilatation most commonly affects left hepatic lobe – MRCP nicely illustrates arborization of peripheral ducts, multiple intrahepatic biliary strictures, and rapidly tapering intrahepatic ducts (arrowhead sign) – Thickening and hyperenhancement of bile duct walls in setting of acute cholangitis ○ Stones within both intrahepatic and extrahepatic ducts

• Etiology uncertain, but likely related to parasitic (Ascaris, Clonorchis) or bacterial infection of biliary tree

(Left) Graphic demonstrates marked dilation of the intrahepatic and extrahepatic bile ducts with multiple common bile duct and intrahepatic stones. (Right) ERCP in a patient with recurrent pyogenic cholangitis (RPC) demonstrates massive dilation of the bile ducts, abnormal arborization of the intrahepatic ducts with a pruned appearance, and innumerable intraductal calculi . This patient later underwent surgery with a choledochoenterostomy.

(Left) Coronal MIP MRCP image in a patient from Southeast Asia demonstrates dilatation of the entire biliary system, with focal severe dilatation of the left hepatic lobe ducts . Notice the multiple low signal stones within the left hepatic ducts. (Right) Axial T2 FS MR in the same patient demonstrates the localized dilatation of the left hepatic lobe ducts with multiple low T2 signal stones . Note that the left lobe is mildly atrophic with subtly increased T2 signal. The findings in this case are classic for RPC.

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– Hyperdense on CT and low in signal on T2WI MR (with variable T1 signal) ○ Lobar or segmental liver parenchymal atrophy associated with sites of greatest biliary dilatation

CLINICAL ISSUES • Almost exclusively occurs in inhabitants of or immigrants from Southeast Asia • Patients present with Charcot triad (RUQ pain, fever, and jaundice) during bouts of acute cholangitis • Complications: Liver abscesses, secondary biliary cirrhosis due to chronic infections, and cholangiocarcinoma • Treatment: Combination of biliary drainage, stone retrieval, treatment of strictures, and antibiotics ○ Surgical resection of involved liver segments or liver transplant are also options

Recurrent Pyogenic Cholangitis

Abbreviations • Recurrent pyogenic cholangitis (RPC)

Synonyms • Oriental cholangitis, oriental cholangiohepatitis, intrahepatic pigment stone disease

Definitions • Disease characterized by formation of pigment stones throughout biliary tree, with resultant biliary strictures and repeated bouts of cholangitis

IMAGING General Features • Best diagnostic clue ○ Intrahepatic and extrahepatic biliary dilatation with multiple biliary calculi • Location ○ May be confined to left lobe (often lateral segment) or less commonly, right posterior segment

Fluoroscopic Findings • ERCP ○ Dilated intrahepatic and extrahepatic bile ducts with disproportionate dilatation of extrahepatic duct – Rapid tapering of dilated intrahepatic ducts with "arrowhead" configuration, arborization of peripheral ducts, and short segment bile duct strictures ○ Common duct and intrahepatic duct stones ○ Nonfilling of biliary ductal segments due to strictures of intrahepatic ducts (missing duct sign)

CT Findings • Dilatation of intrahepatic and extrahepatic biliary ducts ○ Disproportionate dilatation of extrahepatic and central intrahepatic bile ducts: CBD may be markedly enlarged – arborization of peripheral ducts and multiple biliary strictures – Preferential localized dilatation of bile ducts in left hepatic lobe and right posterior hepatic lobe ○ Ductal wall hyperenhancement and heterogeneous liver enhancement during acute cholangitis exacerbation ○ Pneumobilia (may not be related to prior intervention) • Hepatolithiasis and choledocholithiasis ○ ~ 90% of stones are hyperdense to liver ○ Distribution of dilated ducts unrelated to location of calculi • May be associated with pyogenic liver abscesses, bilomas, steatosis, segmental atrophy with chronic biliary obstruction, and cholangiocarcinoma ○ Atrophy most often affects left lateral segment of liver – Atrophic segments may be steatotic with heterogeneous enhancement

MR Findings • Dilatation of intrahepatic and extrahepatic bile ducts, with disproportionate dilatation of extrahepatic and central intrahepatic ducts

○ MRCP nicely illustrates arborization of peripheral ducts, multiple intrahepatic biliary structures, and rapidly tapering intrahepatic ducts (arrowhead sign) – Excellent sensitivity for detection of ductal dilatation, strictures, and calculi – Strictures tend to encompass short segments (< 1 cm) and are easier to see on MRCP compared to CT – Has ability to show ducts proximal to obstruction (advantage over ERCP) ○ Localized intrahepatic biliary ductal dilatation (± biliary stones) most commonly affects left liver lobe, and less commonly, posterior segment of right hepatic lobe – May produce diffuse ductal dilatation in severe cases due to repeated bouts of inflammation ○ May be associated with thickening and hyperenhancement of bile duct walls on T1WI C+ images in setting of acute cholangitis • Stones with low T2WI signal within both intrahepatic and extrahepatic ducts ○ Stones are primarily pigmented stones, and may be diffusely hyperintense or peripherally hyperintense (centrally hypointense) on T1WI ○ Sites of dilated bile ducts may not be closely related to the sites of bile duct stones • Lobar or segmental liver parenchymal atrophy associated with sites of greatest biliary dilatation ○ Atrophic liver may be hypo-, iso-, or hyperintense on T1WI and mildly hyperintense on T2WI to normal liver

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Disproportionate dilatation of extrahepatic and central intrahepatic bile ducts • Hepatolithiasis is seen in ~ 90% of cases ○ Marked variability in echogenicity and acoustic shadowing of calculi • Prominent periportal echogenicity

Imaging Recommendations • Best imaging tool ○ MRCP

DIFFERENTIAL DIAGNOSIS Intrahepatic Stones Secondary to Biliary Stricture • Strictures due to prior surgery, trauma, or chemotherapy • Similar clinical presentation to RPC in setting of cholangitis: RUQ pain, fever, chills

Primary Sclerosing Cholangitis • Multifocal intrahepatic strictures ± strictures of extrahepatic duct with less than expected biliary dilatation ○ Thickening and hyperenhancement of CBD and central ducts due to acute inflammation • Hepatolithiasis can occur proximal to strictures

Ascending Cholangitis • Dilated intrahepatic and extrahepatic ducts, most often as result of obstructing stone ○ Associated with thickening and hyperenhancement of the bile ducts with heterogeneous liver enhancement • Stones, sludge, and infectious debris in bile ducts: Hepatolithiasis uncommon, but rarely occurs 879

Biliary System

Recurrent Pyogenic Cholangitis

• Cystic dilatation of right and left intrahepatic ducts with normal caliber extrahepatic bile duct ○ More commonly segmental involvement of liver rather than diffuse involvement • Central dot sign: Portal vein surrounded by bile duct • May be associated with intrahepatic stones and cholangitis, but less commonly than RPC

○ Almost exclusively in inhabitants of or immigrants from Southeast Asia • Epidemiology ○ Endemic in Southeast Asia – Steady decline in incidence in Asia due to improved standards of living and westernized diet – Increased incidence in North America as result of migration from endemic regions

Cholangiocarcinoma

Natural History & Prognosis

• Increased incidence with sclerosing cholangitis, choledochal cysts, recurrent pyogenic cholangitis, clonorchiasis • Should be suspected in setting of segmental biliary dilatation and segmental liver atrophy • Hepatolithiasis due to chronic ductal dilatation and stasis

• Repeated episodes of cholangitis • Complications ○ Liver abscesses are common, with rare development of abscesses in distant sites (lungs, brain) ○ Biloma formation: Due to obstruction and severe dilatation of bile duct with leakage of bile ○ Portal vein thrombosis: May be secondary to either biliary cirrhosis or periportal inflammation ○ Formation of fistulous tract between biliary tree and peritoneum or intestine ○ Secondary biliary cirrhosis ± portal hypertension ○ Cholangiocarcinoma: Suspect in patient with clinical deterioration and unexplained in alkaline phosphatase – Most commonly occurs within segments with severe atrophy or severe stone burden – Consider if adjacent portal vein narrowed/obliterated • 10% disease-related mortality; 7% biliary cirrhosis; 3% cholangiocarcinoma

Caroli Disease

PATHOLOGY General Features • Etiology ○ Precise etiology is not completely understood, but likely related to parasitic or bacterial infection of biliary tree ○ Different theories based on geographic clustering of disease (suggestive of role of epidemiologic factors) – Parasitic infection □ Parasitic infestation/infection epithelial damage fibrosis stricture bile stasis stone formation □ Liver flukes (Clonorchis sinensis, Opisthorchis species, Fasciola hepatica) and Ascaris lumbricoides – Bacterial infection □ Transient portal bacteremia (from lower GI source) bacterial infection of biliary tree □ Bacterial production of glucuronidases hydrolysis of direct bilirubin to unconjugated bilirubin formation of insoluble calcium bilirubinate □ Lack of host inhibitor of bacterial glucuronidases may play role □ Common cultured bacterial organisms: Escherichia coli, Klebsiella, Pseudomonas, Proteus ○ Associated with poor general nutrition

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Charcot triad (RUQ pain, fever ± rigors, and jaundice) during bouts of acute cholangitis • Other signs/symptoms ○ Recurrent abdominal pain without overt cholangitis ○ Pancreatitis due to passage of biliary stones • Lab data ○ Leukocytosis, alkaline phosphatase, bilirubin ○ All patients should be checked for stool ova and parasites

Demographics • Age ○ Peak incidence in 3rd and 4th decades of life • Gender ○ M=F • Ethnicity 880

Treatment • Multidisciplinary approach ○ Gastroenterology – Extrahepatic biliary drainage, stone retrieval, and stent placement ○ Interventional radiology – Percutaneous biliary drainage of more peripherally affected segments – Basket removal of pigment stones – Balloon dilation of biliary strictures ○ Surgery – Biliary drainage with hepaticojejunostomy – Segmental/lobar liver resection if isolated disease – Liver transplant in most severe cases ○ Medical therapy – Antibiotic therapy during bouts of acute cholangitis – Equivocal role of ursodeoxycholic acid to risk of stone recurrence

DIAGNOSTIC CHECKLIST Consider • RPC in patient from Southeast Asia with diffuse or segmental biliary dilatation, multiple biliary stones, and symptoms of cholangitis

SELECTED REFERENCES 1.

Katabathina VS et al: Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization. Radiographics. 34(3):565-86, 2014

Recurrent Pyogenic Cholangitis Biliary System

(Left) Power Doppler ultrasound shows dilated intrahepatic ducts with intraluminal echogenic calculi . Note the posterior acoustic shadowing . In a patient from Southeast Asia, these imaging findings are characteristic of RPC. (Right) Axial T2 FS MR demonstrates localized dilatation of the right posterior segmental bile ducts with multiple lowsignal internal stones. Localized involvement of the right posterior ducts is less common in RPC than localized involvement of the left lobe ducts.

(Left) Axial NECT in a recent immigrant from Vietnam presenting with RUQ pain, fever, and chills shows highattenuation intrahepatic pigment stones within dilated left lobe bile ducts, and gas within a hepatic abscess in the right hepatic lobe. (Right) Axial CECT in the same patient shows lowattenuation, branching, dilated bile ducts in the left hepatic lobe containing intrahepatic stones , and a stone in the right posterior bile duct .

(Left) Axial CECT in a patient with RPC presenting with fever and RUQ pain shows extensive calculi within dilated right and left bile ducts . Note the absence of peripheral biliary ductal dilatation. (Right) Axial CECT in a patient with RPC shows localized severe dilatation of the left intrahepatic ducts , with an adjacent heterogeneous, solid mass within the left lobe that proved to represent a cholangiocarcinoma. RPC is a known risk factor for the development of cholangiocarcinoma.

881

Biliary System

Ascending Cholangitis KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Pyogenic infection of biliary tree as a result of biliary obstruction

• Primary sclerosing cholangitis • Recurrent pyogenic, AIDS-related, or chemotherapy-related cholangitis

IMAGING • CT and MR findings ○ Dilation of intrahepatic ± extrahepatic ducts with abrupt cut off at site of obstruction ○ Bile duct wall thickening with hyperenhancement ○ Intraductal purulent bile or pus: High density on CT, intermediate to low signal on T1 and T2WI MR ○ Heterogeneous liver enhancement, which can be wedgeshaped, peribiliary, patchy, or diffuse ○ Can be associated with liver abscesses (1/4 of cases) or portal vein thrombosis • Ultrasound findings ○ Dilatation, stenosis, and thickening of bile duct walls with intraluminal echogenic debris (purulent bile)

(Left) Coronal CECT in a patient with fever and leukocytosis after Whipple procedure shows the common bile duct anastomosed to the Roux limb with thickening and hyperenhancement of the bile duct wall and adjacent free fluid , characteristic of ascending cholangitis. (Right) Coronal MRCP in a patient with markedly elevated liver function tests and leukocytosis shows intra- and extrahepatic biliary dilatation. Note the relatively low signal pus and infectious debris within the mid and distal common duct .

(Left) Coronal CECT in a patient presenting with fever and hypotension demonstrates thickening and hyperenhancement of a dilated CBD with a small amount of adjacent fluid , suggesting ascending cholangitis. (Right) Coronal NECT in the same patient demonstrates an obstructing stone as the cause of the patient's cholangitis.

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PATHOLOGY • Pathogenesis: Stone/stricture obstruction bile stasis biliary pressure infection • Source of infection is usually bacteria from duodenum, which ascend biliary tree • Obstruction due to gallstones accounts for 80% of cases • Other common causes include biliary strictures (benign or malignant), recent intervention, and hepatobiliary surgery

CLINICAL ISSUES • Treatment with broad spectrum parenteral antibiotics and biliary drainage (usually via ERCP) • Patients classically present with Charcot triad (pain, fever, jaundice)

Ascending Cholangitis

Synonyms • Bacterial cholangitis, acute cholangitis, suppurative cholangitis, biliary infection

Definitions • Pyogenic infection of biliary tree as a result of biliary obstruction

IMAGING General Features • Best diagnostic clue ○ Biliary ductal dilatation, often with an irregular branching pattern and bile duct wall thickening with hyperenhancement

CT Findings

• Liver abscesses (1/4 of cases) and portal vein thrombosis are common complications

Fluoroscopic Findings • Cholangiography ○ Irregular, thickened bile duct wall with luminal narrowing ○ Ductal stricture or radiolucent filling defect (stone) with obstruction and proximal ductal dilatation ○ Abnormal arborization and tapering of intrahepatic ducts ○ Intrahepatic bile ducts may show communication with hepatic abscesses

Biliary System

TERMINOLOGY

Ultrasonographic Findings • • • •

Dilatation, stenosis, and thickening of bile duct walls Intraluminal echogenic material (purulent bile or pus) Thickened gallbladder wall ± calculi Relatively insensitive for distal CBD stones due to bowel gas

• Dilation of intrahepatic ± extrahepatic ducts (depending on level of obstruction) with abrupt "cut-off" at site of obstruction ○ Obstructing stone of variable density on CT depending on stone type – Sensitivity of CT for stones is variable (25-90%) with roughly 1/4 of stones isoattenuating to bile – Bull's-eye sign: Rim of bile surrounding stone – Meniscus sign at distal common bile duct (CBD) may suggest occult stone (even if stone is low density and not visible) • High-density intraductal debris (purulent bile or pus) • Concentric and diffuse bile duct wall thickening with hyperenhancement • Heterogeneous hepatic parenchymal enhancement: Wedge-shaped, peribiliary, patchy, or diffuse ○ May be more apparent on arterial phase imaging • Can be associated with liver abscesses (1/4 of cases) or portal vein thrombosis ○ Small abscesses may arise adjacent to biliary tree and may communicate with bile ducts

Nonvascular Interventions

MR Findings

Primary Sclerosing Cholangitis

• Intrahepatic biliary dilatation almost always present ± extrahepatic ductal dilatation ○ MRCP nicely demonstrates level of obstruction with abrupt cut-off of duct, as well as abnormal arborization and tapering of intrahepatic ducts ○ Biliary dilatation may be central, diffuse, or segmental • Presence of intermediate to low T2WI and intermediate T1WI signal purulent material (pus) within bile ducts ○ Juxtaposed against normal T2 hyperintense and T1 hypointense bile • Obstructing stones are low signal on T1WI and T2WI • Bile duct walls appear thickened on T1WI and T2WI with progressive hyperenhancement of duct walls on T1WI C+ ○ Often outlined by high T2 signal periportal edema • Diffusely heterogeneous hepatic parenchymal enhancement, which can be wedge-shaped, peribiliary, or patchy in distribution ○ Abnormal enhancement most apparent in arterial and delayed phases

• Segmental strictures with beading and pruning of ducts • Can involve intrahepatic or extrahepatic ducts with thickening/hyperenhancement of duct wall in acute phase • End stage: Cirrhotic-appearing liver with marked hypertrophy of caudate lobe/central liver and preferential atrophy of liver periphery

• ERCP ○ Can be performed (for stone clearance) on an elective basis (after treatment with antibiotics) in patients with mild cholangitis ○ Performed urgently with stent placement in patients with severe cholangitis (hypotension, renal dysfunction, confusion) • Transhepatic cholangiography ○ Option for percutaneous drainage after failed initial ERCP or due to altered biliary anatomy or hilar obstruction

Imaging Recommendations • Best imaging tool ○ US is best screening tool to assess for presence of biliary dilatation/obstruction ○ MRCP or CT helpful in patients with only mild symptoms to assess for cause of obstructions (stone, tumor, etc.)

DIFFERENTIAL DIAGNOSIS

Other Forms of Cholangitis • Recurrent pyogenic, AIDS-related, or chemotherapy-related cholangitis • Patient history is key to correct diagnosis

PATHOLOGY General Features • Etiology ○ Pathogenesis – Stone/stricture obstruction pressure infection

bile stasis

biliary

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Biliary System

Ascending Cholangitis □ Biliary tree normally sterile due to bacteriostatic bile salts, mechanical barrier of sphincter of Oddi, and hepatocyte tight junctions □ Source of infection is usually bacteria from duodenum, which ascend biliary tree, although rarely may be hematogenous □ In cases with hematogenous spread, pressures in biliary tree due to obstruction may disrupt tight hepatocellular junctions and translocate bacteria from blood – biliary pressure adversely affects host defense mechanism (bile flow, tight junctions, IgA production) – biliary pressure results in hepatovenous reflux and bacteremia ○ Risk factors – Choledocholithiasis or hepatolithiasis in 80% of cases □ Most common cause of cholangitis in Western world – Biliary stricture (e.g., primary sclerosing cholangitis or malignancy) □ Malignant obstruction is a very rare cause of cholangitis (except in setting of biliary intervention) – Biliary stents (can act as nidus for infection) – Hepatobiliary surgery – Recent manipulation (i.e., ERCP, sphincterotomy, or percutaneous transhepatic cholangiography [PTC]) – Sphincter of Oddi dysfunction or stenosis ○ Bacteriology – Escherichia coli (25-50%), Klebsiella (15-20%), Enterococcus species (10-20%), Enterobacter species (510%) – Anaerobes (Bacteroides and Clostridia) seen in mixed infections – Parasitic infections (Ascaris, Clonorchis, etc.) common in developing world • Associated abnormalities ○ Liver abscess ○ Portal vein thrombosis due to septic thrombophlebitis

Staging, Grading, & Classification • Tokyo guidelines for initial diagnosis ○ Clinical manifestations (fever, abdominal pain, jaundice) ○ Inflammatory response (leukocytosis, C-reactive protein) ○ Abnormal liver function tests ○ Imaging evidence of etiology (stone, stricture, stent) • Severity of disease ○ Mild (responsive to antibiotic and supportive therapy) ○ Moderate (not responsive to medical therapy, but no organ dysfunction) ○ Severe (organ dysfunction)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ May be a life-threatening condition, although its severity can range from mild to severe ○ Charcot triad (seen in 15-75%): Pain, fever, jaundice – Distinction between cholangitis and cholecystitis often difficult based on clinical presentation and laboratory markers 884

• Other signs/symptoms ○ Reynold pentad: Charcot triad + confusion and hypotension – Present in only a small minority of patients (4-8%) ○ Elderly patients are more likely to have atypical presentations – Hypotension may be only symptom in elderly and patients on steroids ○ Lab findings – WBC, direct bilirubin, alkaline phosphatase, GGT, amylase (concomitant pancreatitis) – transaminases – Positive blood cultures

Demographics • Age ○ 20-50 years (but can occur at any age) • Gender ○ M=F • Epidemiology ○ Most common type of cholangitis in Western countries ○ Usually due to poor nutrition and parasitic infestation in developing countries

Natural History & Prognosis • Complications: Liver abscesses, sepsis, portal vein thrombosis • Prognosis: 20-30% mortality in severe cases (including patients with Reynold pentad)

Treatment • Broad spectrum parenteral antibiotics + decompression/drainage of biliary system ○ 80% respond to conservative therapy and drainage can be delayed and performed on elective basis ○ 20% deteriorate and need urgent drainage • Drainage methods ○ ERCP (preferred): Sphincterotomy with stone extraction ± stenting ○ PTC: When ERCP unavailable, unsuccessful, or not technically feasible – May be necessary with high biliary obstruction, intrahepatic stone, or prior biliary-enteric surgery ○ Cholecystostomy ○ Open surgical decompression

DIAGNOSTIC CHECKLIST Consider • Correlate with clinical and laboratory data to differentiate from other causes of cholangitis

SELECTED REFERENCES 1. 2.

Costello JR et al: MR imaging of benign and malignant biliary conditions. Magn Reson Imaging Clin N Am. 22(3):467-488, 2014 Kochar R et al: Infections of the biliary tract. Gastrointest Endosc Clin N Am. 23(2):199-218, 2013

Ascending Cholangitis Biliary System

(Left) Longitudinal oblique ultrasound in a patient with RUQ pain, leukocytosis, and jaundice shows a markedly thickened CD , suggestive of cholangitis. (Right) Longitudinal oblique ultrasound in a patient with mildly elevated white blood count (WBC) and alkaline phosphatase shows high-level echoes within a markedly dilated CD . An obstructing distal stone and abundant pus were identified at ERCP, compatible with cholangitis.

(Left) Transhepatic cholangiography in a patient S/P biliary-enteric anastomosis shows the anastomosis and proximal ductal dilation. Note the irregular arborization of the ducts and the abrupt "arrowhead" terminations , characteristic of cholangitis. (Right) Axial CECT in a 75year-old woman with fever, RUQ pain, & large complex right lobe hepatic abscess shows that this complication of documented ascending cholangitis was treated successfully with biliary stenting & percutaneous drainage.

(Left) Cholangiogram in a patient with ascending cholangitis shows focal narrowing of the distal right and left hepatic ducts and proximal common hepatic duct . This narrowing is likely due to inflammatory wall thickening associated with bacterial infection. (Right) Cholangiogram in the same patient 2 weeks later following antibiotics shows near complete resolution of bile duct narrowing . The filling defect within the CBD is a blood clot attributable to the imaging procedure.

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Biliary System

Pancreatobiliary Parasites KEY FACTS

TERMINOLOGY • Biliary and pancreatic duct involvement by parasites such as ascariasis, clonorchiasis, echinococcosis, or fascioliasis

IMAGING • Ascariasis: Worms can involve entire biliary tract and PD ○ CT: Linear high-density foci within dilated biliary tree ○ US: Tubular echogenic structure, 3-6 mm in diameter, with central anechoic area (digestive tract of worm) • Clonorchiasis: Flukes typically involve peripheral intrahepatic ducts, not GB, CBD, or PD ○ CT/MR: Preferential dilatation of small peripheral intrahepatic ducts with intraductal high-density foci ○ US: Flukes appear as echogenic filling defects in bile ducts, which float with changes in position • Fascioliasis: Flukes usually involve large intrahepatic ducts, extrahepatic duct, and GB (after liver involvement) ○ CT: Low-density abscesses forming tract from entry site at Glisson capsule into liver parenchyma

(Left) Specimen photograph shows an Ascaris worm retrieved from a bile duct with multiple stones. These biliary parasites may grow up to 30 cm in length. If multiple, they may fill the entire bile duct and produce the so-called spaghetti sign. (Right) Liver flukes are short, flat, somewhat transparent, and taper anteriorly. They have prominent oral and ventral suckers. (Courtesy J. Doss, MD.)

(Left) T-tube cholangiogram of a woman who recently immigrated from China and presented with RUQ pain and symptoms of cholangitis demonstrates a tubular filling defect in the proximal common bile duct from a biliary Ascaris worm. (Right) Ultrasound of the porta hepatis shows an Ascaris worm within the dilated common duct . The worm was mobile at real-time examination. Central hypoechogenicity is thought to represent the digestive tract of the worm. (Courtesy A. Dasyam, MD.)

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– High-density foci within duct lumen represent trematodes with associated mild ductal dilatation • Echinococcosis: Communication of hepatic hydatid cyst with small biliary radicles or rupture of cyst into bile ducts ○ CT: High-attenuation material within dilated bile ducts, often contiguous with wall defect in hepatic hydatid cyst – Air-fluid level within adjacent hydatid cyst may indicate cyst infection or biliary communication ○ US: Linear/round filling defects within dilated bile ducts

CLINICAL ISSUES • Ascariasis most prevalent helminth infection worldwide • Clonorchiasis endemic in Asia and present in Western world secondary to travel and immigration • Echinococcosis endemic in underdeveloped grazing regions (Mediterranean, Africa, South America) • Fascioliasis affects temperate sheep-rearing areas including South America, Europe, China, Africa, and Middle East

Pancreatobiliary Parasites

Definitions • Biliary and pancreatic duct (PD) involvement by parasitic infections (e.g., ascariasis, clonorchiasis, echinococcosis, fascioliasis)

IMAGING General Features • Best diagnostic clue ○ Ascariasis/clonorchiasis: Longitudinal filling defect in bile ducts or PD on ERCP/MRCP ○ Echinococcosis: Dilated, debris-filled biliary ducts adjacent to ruptured hepatic hydatid cyst on CT, US, MR ○ Fascioliasis: Clustered low-density hepatic lesions forming tract from liver capsule into parenchyma on CT/MR • Location ○ Ascariasis may involve entire biliary tract and PD ○ Clonorchiasis typically involves peripheral intrahepatic ducts, not gallbladder (GB), common bile duct (CBD), or PD (except in heavy infections) – Small or medium-sized peripheral ducts typically diffusely dilated, while more central intrahepatic or extrahepatic ducts are normal in caliber ○ Echinococcosis: Any portion of biliary tree can potentially communicate with hydatid cyst ○ Fascioliasis: Usually large intrahepatic ducts, extrahepatic duct, and GB • Size ○ Ascaris: 2-30 cm (3-6 mm thick) ○ Other parasites (Fasciola, Clonorchis) are smaller

CT Findings • Ascariasis/clonorchiasis: Intraductal high-density foci within dilated biliary tree due to biliary worms/flukes or debris ○ Imaging evidence of complications, including peripancreatic inflammation due to pancreatitis, intrahepatic abscess, and abnormal biliary tree wall enhancement or heterogeneous parenchymal enhancement due to cholangitis ○ Characteristic pattern of biliary dilatation in clonorchiasis with preferential dilatation of small peripheral intrahepatic ducts (with sparing of more central ducts) • Echinococcosis: High-attenuation material within dilated bile ducts, often continuous with wall defect in hepatic hydatid cyst ○ Air-fluid level within adjacent hydatid cyst may indicate cyst infection or biliary communication • Fascioliasis: Clustered low-density hepatic abscesses forming a tract from entry site at Glisson capsule into parenchyma ○ High-density foci within duct lumen represent trematodes, usually with associated mild ductal dilatation and ductal wall thickening/hyperenhancement

MR Findings

○ Ascaris worms have characteristic 3-lines appearance on T2WI/MRCP with central high-signal intensity line between 2 low-signal intensity lines • Clonorchiasis: Preferential peripheral biliary dilatation with low-signal filling defects on T2WI or MRCP • Echinococcosis: Low-signal linear or rounded filling defects within dilated ducts, often with adjacent deformed hydatid cyst ○ Direct communication between adjacent irregular hydatid cyst and biliary tree may be demonstrated • Fascioliasis: Liver lesions are low signal on T1WI and high signal on T2WI with extension from liver capsule into deeper liver ○ T2WI and MRCP demonstrate mild ductal dilatation with low-signal filling defects

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Ascariasis: Ultrasound very sensitive for worms in biliary system, but insensitive for worms in duodenum or ampulla (sensitivity for pancreatobiliary ascariasis only 50%) – Tubular echogenic structure, 3-6 mm in diameter, with central anechoic area (digestive tract of worm) – Motility of worms may be evident, and worms that have not moved for 10 days are usually dead – May fill entire bile duct when multiple, producing spaghetti or railway track sign – No acoustic shadowing ○ Clonorchiasis: Flukes appear as echogenic filling defects (without shadowing) in bile ducts which float with changes in position – Often associated with bile duct stones (including hepatolithiasis), which are echogenic and demonstrate posterior acoustic shadowing ○ Echinococcosis: Linear or round filling defects within dilated bile ducts without shadowing ○ Fascioliasis: Abscesses in liver can show variable echogenicity (hypoechoic > hyperechoic) – Ductal thickening and dilatation with mobile fluke sometimes seen within duct lumen

Radiographic Findings • ERCP: Linear, elliptical, or rounded filling defects within dilated biliary tree or PD

Imaging Recommendations • Best imaging tool ○ US as initial imaging modality ○ MRCP may better illustrate parasite within biliary tree or communication of bile duct with hydatid cyst

DIFFERENTIAL DIAGNOSIS Bacterial Cholangitis • Pyogenic infection of biliary tree due to biliary obstruction • Dilated biliary tree with bile duct wall thickening and hyperenhancement, as well as heterogeneous parenchymal liver enhancement

• Ascariasis: MRCP or T2WI demonstrate dilated ducts with linear low-signal filling defects

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Biliary System

Pancreatobiliary Parasites

• Disease associated with formation of pigment stones throughout biliary tree, as well as multiple biliary strictures and repeated bouts of cholangitis • Almost always in patients of Southeast Asian origin • Dilation of biliary tree with disproportionate dilatation of central intrahepatic and extrahepatic ducts, as well as stones in both intrahepatic and extrahepatic ducts • May be related to parasitic (ascariasis, clonorchiasis) or bacterial infection of biliary tree

Biliary Tract Stones • Echogenic nodules within biliary tree with posterior acoustic shadowing on US • Posterior acoustic shadowing uncommon with pancreaticobiliary parasites

Cholangiocarcinoma • Tumor arising from bile duct with characteristic delayed enhancement on multiphase imaging • Mass typically causes biliary dilatation, parenchymal atrophy peripheral to tumor, and capsular retraction • Tumors with predominantly intraductal growth appear more mass-like and infiltrative than parasites

PATHOLOGY General Features • Etiology ○ Ascariasis: Ova ingested, larvae hatch in small bowel – Invade through small bowel mucosa migrate through circulatory system to lungs – Invade alveoli ascend tracheobronchial tree swallowed mature into adult worms in small bowel ○ Clonorchiasis: Flukes ingested with uncooked freshwater fish metacercariae excyst in duodenum move to ampulla of Vater and ascend biliary tree – May live in biliary tree for 15-20 years (usually small- or medium-sized ducts) ○ Echinococcosis: Intermediate host is sheep, while definitive host is dog – Ova ingested reach liver through portal veins – Hydatid cyst is larval stage infection of Echinococcus – Communication of hepatic hydatid cyst with small biliary radicles is common – Frank rupture of cyst into biliary tree occurs in 5-15% ○ Fascioliasis: Humans ingest infected watercress or contaminated water with encysted larva larva penetrates wall of duodenum enters peritoneal cavity and penetrates Glisson capsule to enter liver – Eventually penetrates biliary tract and can survive in bile duct lumen for many years • Associated abnormalities ○ Cholangiocarcinoma with clonorchiasis and ascariasis (may be associated with 6-8x increased risk) ○ Clonorchiasis has strong relationship with recurrent pyogenic cholangitis (RPC)

CLINICAL ISSUES Presentation • Most common signs/symptoms 888

○ Patients with low disease burdens usually asymptomatic ○ RUQ pain (symptoms similar to biliary colic) – Fever, elevated WBC, or sepsis should suggest acute cholangitis, acute cholecystitis, or hepatic abscess ○ Weight loss, diarrhea, jaundice, anorexia, palpitations ○ Small bowel obstruction common with ascariasis (usually due to worms lodged in distal ileum)

Recurrent Pyogenic Cholangitis

Demographics • Age ○ Ascariasis more common in children, but hepatobiliary involvement more common in adults (pediatric biliary tree may be too small for parasites to enter) ○ Clonorchis can colonize bile ducts for 25 years, and symptomatic infections are more common in older adults as disease burden can increase over time ○ Echinococcosis can occur at any age, but involvement of liver/lungs is more common in elderly patients ○ Fascioliasis most often affects young children • Gender ○ Hepatobiliary ascariasis has female predominance (3:1) • Epidemiology ○ Ascariasis most prevalent helminth infection worldwide – 33% of world's population estimated to be infected – Most common in tropical countries (south/southeast Asia) with malnutrition and where untreated sewage is released into drinking water or used for fertilizer ○ Clonorchiasis endemic in Asia and present in Western world secondary to travel and immigration – > 80% of cases in China ○ Echinococcus granulosus endemic in underdeveloped grazing regions (Mediterranean, Africa, South America) ○ Fascioliasis affects sheep-rearing areas (usually temperate climates), including South America, Europe, China, Africa, and Middle East

Natural History & Prognosis • May be asymptomatic with early infection, as clinical symptoms often require heavy parasite load • Complications usually with larger disease burdens, and include acute cholangitis, acute cholecystitis, hepatic abscess, or acute pancreatitis

Treatment • Antihelminthic drugs are primary treatment: Praziquantel is moderately effective for clonorchiasis (20% cure rate with single dose), albendazole is very effective for ascariasis, and triclabendazole is very effective for fascioliasis • Patients with poor response to medications and evidence of acute cholangitis may require endoscopic extraction of parasites or decompression/stenting of biliary system ○ GB involvement generally requires cholecystectomy • Hepatic resection and biliary stenting for hydatid cyst with biliary invasion/rupture

SELECTED REFERENCES 1.

Das AK: Hepatic and biliary ascariasis. J Glob Infect Dis. 6(2):65-72, 2014

Pancreatobiliary Parasites Biliary System

(Left) ERCP shows ascariasis in the main pancreatic duct. Pancreatic duct involvement is much less common than biliary invasion, likely because of the relatively small caliber of the pancreatic duct. Ascariasis-induced pancreatitis is due to either invasion of the pancreatic or biliary ducts. (Right) ERCP demonstrates left duct dilatation and filling defects from intrahepatic flukes. The elongated configuration of the defects suggests flukes rather than intrahepatic biliary calculi.

(Left) Coronal MRCP of a young man with right upper quadrant pain and jaundice shows debris within a dilated extrahepatic duct , irregular right and left hepatic ducts , and an adjacent hydatid cyst . (Courtesy A. Dasyam, MD.) (Right) ERCP in the same patient shows distal duct debris , biliary ductal dilatation, and communication with a partially opacified, ruptured hydatid cyst . Stents may relieve biliary obstruction, but surgical resection of the cyst is ultimately needed. (Courtesy A. Dasyam, MD.)

(Left) Color Doppler ultrasound in a patient with fever and jaundice shows an elongated echogenic filling defect within a dilated left bile duct representing a worm. (Courtesy A. Dasyam, MD.) (Right) Coronal MRCP in the same patient shows intra- and extrahepatic biliary ductal dilatation and Ascaris worm extending from the left bile duct to the distal common bile duct . The distal duct filling defect was ultimately shown to be cholangiocarcinoma, a known complication of ascariasis. (Courtesy A. Dasyam, MD.)

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Biliary System

AIDS Cholangiopathy KEY FACTS

TERMINOLOGY • Spectrum of biliary inflammation caused by AIDS-related opportunistic infections leading to biliary strictures, papillary stenosis, or acalculous cholecystitis

IMAGING • Consider in AIDS patient with very low CD4 count presenting with multiple intrahepatic strictures, papillary stenosis, or gallbladder (GB) wall thickening • US: Dilated intrahepatic ducts with common bile duct (CBD) thickening and periductal hyper-/hypoechoic areas ○ Diffuse GB thickening ± sonographic Murphy sign in setting of acalculous cholecystitis • MR: Papillary stenosis with tapered narrowing of distal CBD and proximal CBD dilatation ○ ± long-segment extrahepatic bile duct strictures ○ ± thickening and hyperenhancement of bile duct wall on T1WI C+ images in setting of acute inflammation

(Left) Cholangiogram demonstrates a pruned appearance of the extrahepatic biliary tree with multiple beaded strictures, attributable in this case to AIDS cholangiopathy given the patient's very low CD4 count. (Right) Ultrasound of the portal hepatis in a man with Cryptosporidium cholangitis shows tapered narrowing of a dilated distal common bile duct (CBD) and wall thickening . (Courtesy K. Hosseinzadeh, MD.)

(Left) ERCP shows abnormal intrahepatic ductal arborization, with foci of stricture, dilation, and abrupt termination of ducts. The common duct is dilated, and the distal duct is strictured . Intrahepatic biliary strictures in AIDS cholangitis can resemble those seen in PSC. (Right) MRCP shows strictured intrahepatic ducts , extrahepatic biliary ductal dilatation, a narrowed distal CBD , and papillary stenosis . This combination is characteristic of AIDS cholangiopathy. (Courtesy V. Kabathina, MD.)

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○ Beaded appearance of intrahepatic ducts with alternating strictures, normal ducts, and dilated ducts ○ GB wall thickening and pericholecystic inflammation • ERCP: Papillary stenosis with proximal CBD dilation, strictures/ulcerations of CBD, and intrahepatic strictures

TOP DIFFERENTIAL DIAGNOSES • • • •

Primary sclerosing cholangitis Acute pyogenic cholangitis Secondary sclerosing cholangitis (IgG4-related, ischemic) Ampullary stenosis

CLINICAL ISSUES • Late-stage AIDS patients usually with CD4 < 100 cells/mm³ • Now considered rare condition due to HAART • Patients present with RUQ pain, fever, weight loss, diarrhea, and markedly elevated alkaline phosphatase • Primary treatment is reconstituting immune function using HAART, which can reverse cholangiopathy in some cases

AIDS Cholangiopathy

IgG4-Related Sclerosing Cholangitis

Definitions

• Infiltration of biliary tree by IgG4-positive plasma cells • Can result in strictures of intrahepatic or extrahepatic ducts

• Spectrum of biliary inflammation caused by AIDS-related opportunistic infections leading to biliary strictures/obstruction or acalculous cholecystitis

Ischemic Cholangitis

IMAGING

• Usually after liver transplant or surgical injury to vasculature • Multiple intrahepatic and extrahepatic strictures may appear identical to PSC or AIDS cholangiopathy

General Features

Ampullary Stenosis

• Size ○ Short or long segment biliary strictures

• Smooth distal CBD stricture without ulceration possibly due to passage of CBD stones or chronic pancreatitis

Radiographic Findings • ERCP: Papillary stenosis with proximal CBD dilation, CBD strictures/ulcerations, and multiple intrahepatic strictures ○ Combination of ampullary stenosis and intrahepatic strictures is unique to AIDS cholangiopathy

CT Findings • CECT ○ Dilatation of CBD with tapered narrowing of distal CBD – ± thickening and hyperenhancement of CBD wall ○ Beaded appearance of intrahepatic ducts: Alternating sites of narrowing, normal ducts, and dilated ducts ○ Gallbladder (GB) wall thickening and pericholecystic fat stranding in patients with acalculous cholecystitis

MR Findings • MR/MRCP very sensitive (85-100%) and specific (92-100%) • Papillary stenosis with tapered narrowing of distal CBD (without abrupt margins) and proximal CBD dilatation ○ ± long-segment extrahepatic bile duct strictures – ± thickening and hyperenhancement of bile duct wall on T1WI C+ in setting of acute inflammation • Intrahepatic ductal strictures resembling PSC ○ Multifocal sites of alternating strictures, normal caliber ducts, and dilated ducts producing beaded appearance ○ Greater than expected visualization of intrahepatic ducts on MRCP should suggest intrahepatic strictures

Ultrasonographic Findings • Dilated intrahepatic ducts with CBD thickening and periductal hyper-/hypoechoic areas • Diffuse GB thickening ± sonographic Murphy sign in the setting of acalculous cholecystitis

DIFFERENTIAL DIAGNOSIS Primary Sclerosing Cholangitis • Beaded and pruned appearance of intrahepatic ducts with asymmetric short segment strictures alternating with normal sized ducts and sites of saccular dilatation ○ Involvement of intrahepatic ducts is indistinguishable from AIDS cholangiopathy without clinical history • Can also involve CBD with beaded strictures and pseudodiverticula, but no papillary stenosis

Acute Pyogenic Cholangitis • Usually results from distal CBD obstruction • Biliary dilatation with hyperenhancement/thickening of bile duct walls and heterogeneous liver enhancement

Biliary System

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ AIDS-related opportunistic infection of biliary tract – Cryptosporidium, Microsporidia, cytomegalovirus (CMV), and Cyclospora most common ○ Strictures may also be due to CMV-related vasculitis

Staging, Grading, & Classification • • • •

Type I (15-20%): Distal CBD stricture from papillary stenosis Type II (20%): Diffuse intrahepatic biliary strictures Type III (50%): Combined types I and II Type IV (15%): Long segment stricture of CBD ± intrahepatic ductal involvement • Type V: Acalculous cholecystitis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ RUQ pain (most common with papillary stenosis) ○ Fever (~ 33%) and jaundice (10-20%) • Clinical profile ○ Significantly alkaline phosphatase ○ Mildly bilirubin, GGT, and AST/ALT

Demographics • Epidemiology ○ Late-stage AIDS (classically CD4 < 100 cells/mm³) ○ Now considered a rare condition in AIDS population due to highly active antiretroviral therapy (HAART)

Natural History & Prognosis • Poor prognosis since AIDS cholangiopathy is usually seen in patients with advanced AIDS

Treatment • Primary treatment is reconstitution of immune function using HAART, which can reverse cholangiopathy (including imaging findings) in some cases ○ Antimicrobial therapy usually ineffective • Sphincterotomy in symptomatic patients with papillary stenosis ± stent placement for dominant strictures

SELECTED REFERENCES 1.

Katabathina VS et al: Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization. Radiographics. 34(3):565-86, 2014

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Biliary System

Gallbladder Hydrops and Empyema KEY FACTS

TERMINOLOGY • Gallbladder (GB) hydrops: Distended GB secondary to chronic obstruction filled with watery mucoid material ○ Content usually sterile without GB inflammation • GB empyema: Pus-filled, inflamed, and distended GB secondary to acute cholecystitis with suppurative intraluminal infection

IMAGING

PATHOLOGY

• Hydrops ○ CECT: Distended GB filled with low-density contents – Usually no wall thickening, pericholecystic fluid, or adjacent fat stranding ○ US: Distended GB with anechoic and simple contents – GB wall appears thin or normal – Negative sonographic Murphy sign – Gallstones usually (but not always) present • Empyema ○ CECT: Distended GB with intraluminal contents > 15 HU

• GB hydrops caused by chronic GB outlet obstruction (most commonly due to impacted stone) • Empyema caused by bacterial infection of bile within inflamed GB, usually in setting of acute cholecystitis

(Left) Oblique ultrasound shows an enlarged gallbladder in a 5 year old with fever and right upper quadrant pain. The hydropic gallbladder led to the diagnosis of Kawasaki disease, a known predisposing factor for hydrops in children. (Courtesy R.J. Fleck, Jr., MD.) (Right) Axial CECT in a cirrhotic patient with RUQ pain demonstrates that the gallbladder is distended but thin-walled, and a stone is present within the cystic duct , findings consistent with gallbladder hydrops.

(Left) Ultrasound in an elderly patient with sepsis shows a massively dilated and elongated gallbladder with a thick wall and rounded but mobile internal echogenic sludge. (Right) Coronal NECT in the same patient shows the dilated gallbladder with thickened wall . Because the patient was considered a poor surgical candidate, she was treated with percutaneous cholecystostomy, which yielded thick bile with a heavy growth of bacteria, consistent with empyema of the gallbladder.

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– Wall thickening with pericholecystic fat stranding and fluid (similar to conventional cholecystitis) – Advanced cases may show gangrene or perforation ○ US: Markedly distended GB with echogenic pus in lumen – GB wall appears thickened – Sonographic Murphy sign often positive – Gallstones usually (but not always) present

CLINICAL ISSUES • • • •

Hydrops: RUQ pain without fever or signs of infection Fever or WBC with dilated GB concerning for empyema Cholecystectomy for GB hydrops if patient is symptomatic Urgent cholecystectomy for empyema

Gallbladder Hydrops and Empyema

Synonyms • Hydrops: Mucocele • Empyema: Suppurative cholecystitis

Definitions • Hydrops: Distended gallbladder (GB) secondary to chronic obstruction filled with watery mucoid material ○ Content is usually sterile without GB inflammation • Empyema: Pus-filled, inflamed, and distended GB secondary to acute cholecystitis with suppurative intraluminal infection

IMAGING General Features • Best diagnostic clue ○ Rounded, distended GB filled with either anechoic watery mucoid content (hydrops) or echogenic pus (empyema) • Location ○ Markedly distended GB can extend downwards into pelvis in most severe cases • Size ○ GB distended > 5 cm transverse diameter ○ Size can reach up to 1.5 liters

Imaging Recommendations • Best imaging tool ○ Ultrasound

CT Findings • Hydrops ○ Markedly distended GB filled with low-density contents ○ Usually thin wall with minimal inflammatory change – Typically no evidence of overt wall thickening, pericholecystic fluid, or adjacent fat stranding • Empyema ○ Markedly distended GB with high-density intraluminal contents > 15 HU ○ GB wall thickened > 5 mm ○ Gallstones usually present, but not always visible on CT ○ Pericholecystic fluid and fat stranding ○ Advanced cases may demonstrate evidence of wall gangrene or perforation, including areas of diminished wall enhancement, frank defect in GB wall, or pericholecystic fluid collection

MR Findings • Hydrops ○ Distended GB with internal contents demonstrating simple fluid signal (high T2WI and low T1WI) ○ No evidence of wall edema or adjacent inflammation ○ Gallstones usually present (usually visible as signal voids on all sequences) • Empyema ○ Distended GB with internal contents demonstrating variable signal depending on proportion of bile, pus, and blood ○ High signal edema in thickened GB wall on T2WI ○ Pericholecystic fluid and fat stranding

Ultrasonographic Findings • Markedly distended GB in both hydrops and empyema ○ GB wall appears thin or normal in hydrops ○ GB wall appears thickened (often asymmetric) in empyema • Sonographic Murphy sign negative in hydrops, but often positive in empyema • GB contents appear anechoic and simple in hydrops • Echogenic pus in lumen, similar in echogenicity to sludge, in empyema • Gallstones often present in both hydrops and empyema, but may also be acalculous • Look for imaging signs of GB gangrene ○ Intraluminal membranes from sloughed mucosa ○ Discrete defects in GB wall with pericholecystic fluid collections ○ Asymmetric wall thickening with irregularity and ulcerations

Biliary System

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Gangrenous Cholecystitis • GB wall necrosis and gangrene occurs in 1/4 of patients with acute cholecystitis (usually elderly, diabetic, or immunocompromised patients) • May result from progression of GB hydrops and places patient at risk for perforation • Ultrasound findings: Asymmetric GB wall thickening with ulceration and irregularity of wall ○ Intraluminal membranes secondary to sloughed mucosa ○ Flow to involved portions of GB wall may be absent on color Doppler US • CECT: Patchy or diminished enhancement of portions of GB wall ○ Discrete defect in GB wall may be present ± pericholecystic fluid collection/abscess

Emphysematous Cholecystitis • Secondary infection of GB with gas-forming organism (such as Clostridium welchii) • Ultrasound demonstrates gas in GB wall with "dirty" posterior acoustic shadowing, ring-down artifact from gas bubbles, and champagne sign (effervescent gas bubbles rising within GB) • CT demonstrates GB wall thickening with gas within GB lumen or wall

Courvoisier Gallbladder • Simultaneous chronic obstruction of GB and CBD due to obstructing pancreatic head or ampullary mass • GB may be massively distended, but usually in conjunction with severe intrahepatic and extrahepatic biliary dilatation • Usually discrete mass present at ampulla or pancreatic head with abrupt obstruction of CBD ± pancreatic ductal obstruction

Choledochal Cyst • May superficially mimic hydropic GB, particularly on US • Distinction made readily on CT or MR, as GB is visualized as separate structure from choledochal cyst

893

Biliary System

Gallbladder Hydrops and Empyema

PATHOLOGY General Features

Presentation

• Etiology ○ Hydrops: Chronic GB outlet obstruction – Impacted stone in neck/cystic duct (most common) – GB tumors or polyps (usually near GB neck or cystic duct) – Extrinsic compression of GB outlet by tumor, lymph node, or fibrosis – Prolonged TPN – Ceftriaxone – Congenital narrowing of cystic duct – Parasites (rare): Ascariasis ○ Empyema: Bacterially contaminated bile within inflamed GB – Most common organisms are Escherichia coli and Klebsiella – Most commonly develops due to acute calculous or acalculous cholecystitis, but can also result from super-infection in setting of malignant obstruction of GB • Associated abnormalities ○ Hydrops can be seen in association with Kawasaki syndrome in children – Most cases in children unrelated to gallstones and are attributable to infections or Kawasaki syndrome – Less common associations □ Streptococcal pharyngitis □ Mesenteric adenitis □ Typhoid fever □ Hepatitis □ Nephrotic syndrome □ Familial Mediterranean fever • Pathophysiology ○ Hydrops – GB outlet obstruction GB distention – Continued resorption of bile and bile pigment and continued secretion from mucosa clear and watery mucoid content – Increased GB volume is also associated with GB dyskinesia: Advanced age, diabetes, obesity

• Most common signs/symptoms ○ Hydrops often presents with RUQ pain or palpable GB – Usually no systemic signs of infection or focal tenderness in RUQ ○ Presence of fever, chills, or WBC with distended GB raises concern for acute cholecystitis and empyema – Symptoms of GB empyema similar to conventional acute cholecystitis – Tender to palpation in RUQ (positive Murphy sign) • Other signs/symptoms ○ Empyema: Generalized sepsis if untreated

Gross Pathologic & Surgical Features • Hydrops ○ Thin-walled, distended GB with minimal inflammatory changes • Empyema ○ Acute cholecystitis with intraluminal pus, ± gallstones

Microscopic Features • Hydrops ○ Flattened mucosa lined by columnar or cuboidal cells ○ number of Rokitansky-Aschoff sinuses • Empyema ○ Acute inflammation within GB wall with submucosal edema and hemorrhage ○ Pus and WBC debris in GB lumen

894

CLINICAL ISSUES

Demographics • Age ○ Usually > 65 years ○ Can rarely occur in children (17 months to 7 years) • Gender ○ M 2 mm ○ Brightly echogenic nodule in GB with marked posterior acoustic shadowing – Small stones may not shadow – Stones should be mobile when repositioning patient – May show "twinkling" artifact on color Doppler images ○ Wall-echo-shadow sign when GB is filled with stones – Anterior GB wall demarcated by echogenic line (wall), followed by layer of bile demarcated by hypoechoic line (echo), followed by posterior acoustic shadowing from superficial stones (shadow) – Posterior wall of GB or deeper stones not visible due to acoustic shadowing ○ US not sensitive for detection of choledocholithiasis – Distal CBD often obscured by bowel gas • Sludge ○ Layering material in dependent portion of GB which should shift slowly with repositioning of patient – Variable echogenicity: May be uniformly echogenic, hypoechoic with punctate hyperechoic foci, or heterogeneous echogenicity – No posterior acoustic shadowing – Side lobe artifact may mimic sludge ○ Can assume rounded or mass-like configuration (tumefactive sludge) – Unlike intraluminal mass, no vascularity on Doppler US and should be mobile when patient is repositioned – Wall of gallbladder should be intact (unlike cancer)

DIFFERENTIAL DIAGNOSIS GB Intraluminal Polyp • Immobile nodule with internal color flow vascularity • Cholesterol polyps may demonstrate "comet tail" artifact

GB Adenomyomatosis • Segmental thickening or cystic mass at GB fundus • No posterior acoustic shadowing, but often associated with tiny echogenic foci that demonstrate "comet tail" artifact

GB Carcinoma • Immobile mass in GB with internal color flow vascularity

897

Biliary System

Gallstones and Sludge

• May fill GB (making identification of GB difficult) and can extend through GB wall to involve adjacent organs • 75% of patients with GB cancer have associated gallstones

Emphysematous Cholecystitis • Echogenic reflectors (gas) with dense posterior acoustic shadowing which may mimic a GB filled with stones • "Dirty" acoustic shadowing, ring-down artifact, and lack of wall-echo-shadow complex suggest correct diagnosis

Porcelain Gallbladder • Echogenic curvilinear structure in gallbladder fossa with dense posterior acoustic shadowing • No wall-echo-shadow complex and posterior wall of GB may be visualized (unlike stones filling GB)

PATHOLOGY General Features • Etiology ○ Cholesterol stones – Bile supersaturation GB mucosal inflammation procrystalizing proteins secretion crystallization stone growth □ Risk factors: age, obesity, rapid weight loss, pregnancy, female, slow intestinal transit, ileal disease, high-fat diet, medication (e.g., clofibrate) – ↓ GB motility increases rate of crystallization and stone growth □ Risk factors for decreased motility: Pregnancy, oral contraceptives, TPN, octreotide, rapid weight loss ○ Pigment stones – Black stone: unconjugated bilirubin, normal cholesterol concentration, altered pH (due to mucosal inflammation) □ Associated with chronic hemolysis, cirrhosis, TPN – Brown stone: Infection leads to release of bacterial glucuronidases, which hydrolyze bilirubin glucuronides and form calcium bilirubinate solution □ Usually seen in malnourished Asian subpopulations (recurrent pyogenic cholangitis) □ Associated with cholestasis and biliary infections ○ Sludge – Composed of various proportions of cholesterol monohydrate crystals, calcium bilirubinate, and mucus □ Sludge composed primarily of cholesterol crystals will not be evident on CT – Similar pathogenesis to biliary stones – Associated with rapid weight loss, pregnancy, fasting, TPN, critical illnesses, medications (e.g., ceftriaxone)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most patients with gallstones/sludge are asymptomatic ○ Biliary colic: Dull aching pain in right upper quadrant with radiation to back or right shoulder – May be triggered by eating (especially fatty foods), but does not have to be postprandial – Caused by GB contracting against stone temporarily lodged within cystic duct or GB neck 898

– No fever or jaundice; normal lab tests (AST/ALT, alkaline phosphatase, WBC, etc.)

Demographics • Age ○ Prevalence increases with age ○ Gallstones rare in children (usually hemolytic disorder) • Gender ○ 2-3x more common in women • Ethnicity ○ Native Americans (Pima Indian) and Scandinavians have risk of cholesterol gallstones ○ Asian populations have risk of pigment stones • Epidemiology ○ Gallstone prevalence: 10-15% of adult population in USA ○ Incidence of gallstones with certain diseases: Crohn disease, cirrhosis, hemolytic disorders

Natural History & Prognosis • Gallstone symptoms resolve completely in > 50% • Sludge progresses to gallstones in 15% • Common complications ○ Risk of complications ~ 1% per year ○ Acute cholecystitis (36%), acute pancreatitis (gallstones cause 30% of acute pancreatitis), choledocholithiasis (3%), GB cancer or cholangiocarcinoma (0.3%) • Rare complications ○ Biliary-enteric fistula: Untreated gallstones that erode into bowel; most often cholecystoduodenal fistulas ○ Gallstone ileus: Migration of stone into bowel through fistula with obstruction of bowel at distal ileum – Rigler triad present in only 1/3 of cases: Small bowel obstruction, pneumobilia, and stone in GI tract ○ Bouveret syndrome: Gastric outlet obstruction due to stone in duodenum or distal stomach ○ Dropped gallstones: Gallstones spilled into abdomen during laparoscopic cholecystectomy – May be asymptomatic or serve as nidus for infection

Treatment • Gallstones ○ No treatment for patients who are asymptomatic ○ Surgical treatment is 1st option: Cholecystectomy (open or laparoscopic), ERCP (for choledocholithiasis) – Cholecystectomy does not resolve symptoms of biliary colic in ~ 10% of patients ○ Medical treatment in patients not considered surgical candidates: Dissolution therapy with oral bile acids or extracorporeal shock-wave lithotripsy • Sludge ○ No treatment for patients who are asymptomatic ○ Cholecystectomy (open or laparoscopic) if symptomatic

SELECTED REFERENCES 1.

Raman SP et al: Abnormalities of the distal common bile duct and ampulla: Diagnostic approach and differential diagnosis using multiplanar reformations and 3D imaging. AJR Am J Roentgenol. 203(1):17-28, 2014

Gallstones and Sludge Biliary System

(Left) Transverse US shows a wall-echo-shadow complex caused by stones filling the GB. The "wall" is the outer echogenic stripe delineating the GB wall, the "echo" is the hypoechoic stripe created by a thin layer of bile , and the "shadow" is the posterior acoustic shadowing behind a superficial layer of stones. (Right) US shows multiple echogenic stones in the CBD. The stones are associated with posterior acoustic shadowing and cause mild CBD dilatation .

(Left) Coronal volumerendered CECT demonstrates a stone in the distal CBD resulting in mild upstream CBD dilatation. CT is only 80% sensitive for gallstones, although identification of stones in the CBD is easier when causing biliary obstruction. (Right) ERCP image in the same patient demonstrates the stone as a well-defined, faceted filling defect in the CBD.

(Left) Axial CECT shows gas with a "Mercedes-Benz" shape within a large gallstone. The gas itself is of no diagnostic significance and is not a sign of infection. This patient has cholecystitis, evidenced by GB wall thickening . (Right) Frontal abdominal radiograph shows a GB filled with innumerable opaque calculi . Calcium bilirubinate stones are typically multiple, small, and radiopaque. A feeding tube marks the 2nd portion of the duodenum.

899

Biliary System

Gallstones and Sludge

(Left) Frontal radiograph shows a ring-shaped or "eggshell" calcification in the right upper quadrant, a typical appearance for a large gallstone. (Right) Axial T2WI MR in the same patient demonstrates a large, hypointense stone (with some linear higher signal within the stone) in the proximal common duct near the confluence of the ducts. Stones are typically hypointense on T1WI & T2WI, but as in this case, can be have somewhat heterogeneous signal with areas of higher signal within the stone.

(Left) Coronal MRCP MIP reconstruction in the same patient demonstrates that the large stone , visible as a large, hypointense filling defect in the proximal common duct, is causing significant biliary obstruction. (Right) MRCP shows 2 gallstones within the GB, but normal bile ducts. This patient had a CT scan on which these stones were not visible, since cholesterol stones are often isodense to bile.

(Left) Axial T2 FS MR demonstrates a low signal filling defect in the distal CBD, the characteristic appearance of a stone on MR. (Right) Coronal CECT demonstrates dilated small bowel , a calcified stone at the site of transition, and pneumobilia , the classic Rigler triad of findings associated with gallstone ileus. Gallstones typically enter the bowel through a cholecystoduodenal fistula.

900

Gallstones and Sludge Biliary System

(Left) Axial NECT in a patient who had undergone prior cholecystectomy demonstrates a dropped calcified gallstone in the hepatorenal fossa. Dropped gallstones can be asymptomatic or serve as the nidus for future infection. (Right) Ultrasound demonstrates a typical appearance of sludge , with hypoechoic material layering within the GB. Notice the lack of posterior acoustic shadowing, unlike the gallstone also seen in the GB.

(Left) Sagittal ultrasound demonstrates material of mixed echogenicity filling the GB lumen, an appearance consistent with sludge. (Right) Sagittal ultrasound demonstrates echogenic sludge filling the GB lumen. Sludge can vary greatly in its appearance, ranging from hypoechoic to hyperechoic.

(Left) Sagittal ultrasound demonstrates an echogenic mass in the GB. Notice that bile outlines the entirety of the mass without a clear attachment to the wall, and there is no acoustic shadowing. (Right) Sagittal color Doppler ultrasound in the same patient shows no vascularity within the mass . The mass was noted to be mobile when the patient was repositioned. These are characteristic features of tumefactive sludge, which should not be confused with malignancy.

901

Biliary System

Acute Calculous Cholecystitis KEY FACTS

• Acute inflammation of gallbladder (GB) precipitated by an obstructing calculus within GB neck or cystic duct

IMAGING • Ultrasound findings ○ Cholelithiasis, sonographic Murphy sign, and GB wall thickening • CT findings ○ Distended GB (measuring > 5 cm in short axis) ○ GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement and pericholecystic fat stranding ○ Calcified gallstones may be visualized (15% of cases) ○ Hyperenhancement of adjacent liver parenchyma • Hepatobiliary scintigraphy (Tc99-HIDA) ○ Nonvisualization of GB 4 hours after injection of radiotracer (or 30 minutes after administration of morphine) • Complications

(Left) Transverse US shows a large echogenic stone with an acoustic shadow and a thickened gallbladder (GB) wall. These findings, along with a positive sonographic Murphy sign, suggested acute cholecystitis, confirmed at surgery. (Right) This hepatobiliary scan is of a 48year-old woman with RUQ pain and surgically confirmed acute cholecystitis. Note the presence of bowel , absence of GB activity, and a subtle GB fossa rim sign . Persistent pericholecystic activity may be due to tissue edema and biliary stasis.

(Left) Axial CECT demonstrates a tiny stone within the gallbladder, with thickening of the GB wall, pericholecystic free fluid , and fat stranding , a constellation of findings diagnostic of acute cholecystitis. (Right) Axial CECT of a 37-year-old woman shows GB wall thickening and GB fossa hyperenhancement . This surrounding hepatic parenchymal hyperemia is analogous to the rim sign of hepatobiliary scintigraphy.

902

○ Gangrenous cholecystitis: GB wall necrosis with morbidity/mortality ○ Perforated cholecystitis: Most often occurs due to progressive GB distension with eventual rupture ○ Emphysematous cholecystitis: Secondary infection of GB with gas-forming organisms ○ Hemorrhagic cholecystitis: Hemorrhage within GB lumen or wall

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • •

Acalculous cholecystitis Nonspecific GB wall thickening Peptic ulcer disease Acute pancreatitis

CLINICAL ISSUES • Immediate cholecystectomy in patients who are good surgical candidates • Percutaneous cholecystostomy with antibiotics in patients who are high-risk surgical candidates

Acute Calculous Cholecystitis

Definitions • Acute inflammation of gallbladder (GB) precipitated by an obstructing calculus within GB neck or cystic duct

IMAGING General Features • Best diagnostic clue ○ Cholelithiasis, with an impacted, immobile stone within GB neck or cystic duct ○ GB wall thickening ○ Positive sonographic Murphy sign: Pain with insonation directly over GB (accentuated during deep inspiration) – May be absent in elderly, anesthetized, or diabetic patients, or those with GB necrosis • Morphology ○ Distended GB more rounded than normal pear-shaped configuration

Fluoroscopic Findings • ERCP ○ No filling of GB with contrast as result of cystic duct/GB neck obstruction by stone ○ May document common bile duct (CBD) stones in patients with associated choledocholithiasis

CT Findings • Uncomplicated cholecystitis ○ Distended GB (measuring > 5 cm in short axis) ○ GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement and pericholecystic fat stranding ○ Cholesterol/bilirubin stones typically not visible, but calcified gallstones may be visualized (15% of cases) ○ Hyperenhancement of liver parenchyma adjacent to inflamed GB (particularly in arterial phase) • Complicated cholecystitis ○ Gangrenous cholecystitis:Focal interruption or lack of enhancement of GB wall due to necrosis – Small ulcerations or outpouchings of GB wall may occur at these sites – Intraluminal linear membranes (secondary to sloughed mucosa) – Intramural or pericholecystic abscesses ○ Emphysematous cholecystitis: Gas in lumen/wall of GB – CT is best modality to identify ectopic gas and make diagnosis of emphysematous cholecystitis ○ Hemorrhagic cholecystitis: High-attenuation intraluminal clot ± active extravasation of contrast – Blood within GB lumen or bile ducts ○ Gallbladder perforation:Focal pericholecystic fluid collection or abscess adjacent to disrupted GB wall; extraluminal gallstones – CT better than US for visualizing GB wall defect

MR Findings • Distended GB with wall thickening, gallstones, and pericholecystic fat stranding/fluid • Hyperenhancement of GB wall and mucosa on T1WI C+, with possible enhancement of surrounding liver parenchyma (rim sign)

• Stones in GB or cystic duct on T2WI or MRCP • Interrupted GB wall/focally absent mucosal enhancement gangrenous or perforated GB • Use of hepatobiliary contrast agents (such as Eovist), which are normally secreted into bile, may be helpful ○ Lack of filling or delayed filling (> 60 minutes) of GB supports diagnosis of acute cholecystitis ○ Normal filling (< 60 minutes) does not exclude cholecystitis

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Uncomplicated cholecystitis – Cholelithiasis (usually an immobile, impacted stone in GB neck or cystic duct), sonographic Murphy sign, and GB wall thickening > 3 mm – GB distension > 5 cm in short axis ○ Complicated cholecystitis – Perforated cholecystitis: Pericholecystic abscess with collapsed GB □ Sonographic hole sign: Visualization of GB wall defect on US – Gangrenous cholecystitis: Asymmetric wall thickening, intraluminal linear membranes, and irregularity and ulcerations of GB wall □ Striated GB, contrary to prior teaching, not convincingly associated with gangrene – Emphysematous cholecystitis: Gas in GB lumen and wall (brightly echogenic reflectors with dense "dirty" posterior acoustic shadowing) □ GB itself may be difficult to visualize as result of shadowing from gas – Hemorrhagic cholecystitis: Echogenic clot within GB lumen or visualized biliary tree • Color Doppler ○ Increased vascularity of GB wall (flow may be absent in gangrenous cholecystitis)

Nuclear Medicine Findings • Hepatobiliary scintigraphy ○ Nonvisualization of GB 4 hours after radiotracer injection (or 30 minutes after morphine administration) ○ Increased uptake in GB fossa (rim sign) due to hyperemia in 35% of patients – Very specific (but not sensitive) for acute cholecystitis ○ Hepatobiliary scintigraphy more sensitive (97%) and specific (90%) compared to US (88% and 80%, respectively) ○ False-positive results in patients who have recently eaten, undergone prolonged fasting (> 24 hours), received hyperalimentation, have severe concurrent illness, or who have severe hepatocellular dysfunction

Imaging Recommendations • Best imaging tool ○ US is best screening tool ○ Hepatobiliary scintigraphy for confirmation (particularly when US is equivocal) ○ CECT to evaluate potential complications

903

Biliary System

Acute Calculous Cholecystitis

DIFFERENTIAL DIAGNOSIS Acalculous Cholecystitis

Presentation

• Non stone-related GB inflammation due to ischemia and stasis usually diagnosed in critically ill patients

• Enlarged pancreas with peripancreatic fluid or inflammatory changes • GB may show reactive wall thickening

• Most common signs/symptoms ○ Acute right upper quadrant pain that may radiate to shoulder or back ○ Fever, nausea, vomiting, and anorexia • Lab data ○ Increased WBC + bandemia ○ May have mild in AST/ALT and amylase ○ alkaline phosphatase/bilirubin raises concern for complication (Mirizzi syndrome, cholangitis, choledocholithiasis)

Peptic Ulcer Disease

Demographics

• Thickened duodenum with periduodenal inflammatory changes and ectopic gas (with perforation) • GB may show reactive wall thickening

• Age ○ Typically > 25 years • Gender ○ M:F = 1:3 • Epidemiology ○ Gallstones cause 90% of cases of acute cholecystitis ○ Increased incidence of gallstones in selected populations – Latinos, Pima Indians, and Scandinavians ○ Incidence of acute cholecystitis parallels prevalence of gallstones – 25 million Americans have gallstones

Nonspecific Gallbladder Wall Thickening • Most common causes: Hepatitis, hypoalbuminemia, congestive heart failure, ascites, renal failure, etc.

Acute Pancreatitis

Hepatic Flexure Diverticulitis • Colonic diverticulosis with colonic wall thickening and pericolonic inflammation • GB may show reactive wall thickening

PATHOLOGY General Features • Etiology ○ Impacted stone within GB neck/cystic duct • Pathophysiology ○ Not fully explained by cystic duct obstruction alone ○ Epithelial injury due to stone impaction release of proinflammatory mediators (such as lysolecithin) production of additional inflammatory mediators (prostaglandins) GB inflammation ○ Secondary infection also plays a role, although not all patients have infected bile – Seen in 22-46% of cases – Escherichia coli, Enterococcus, Klebsiella, Enterobacter

Staging, Grading, & Classification • Gangrenous cholecystitis ○ GB wall necrosis and gangrene: 1/4 of patients ○ morbidity/mortality ○ Most common in elderly, diabetic, and immunocompromised patients • Perforated cholecystitis ○ More likely with acute acalculous cholecystitis ○ Most often occurs due to progressive GB distension with eventual rupture ○ Perforated cholecystitis can result in pericholecystic abscess (including within liver) • Emphysematous cholecystitis ○ Secondary infection of GB with gas-forming organisms (e.g., Clostridium welchii) ○ Strong male predominance, especially in diabetics ○ Carries 5x greater risk of GB perforation • Hemorrhagic cholecystitis ○ Hemorrhage itself may cause cholecystitis by obstructing cystic duct with blood products ○ Can be caused by calculous or acalculous cholecystitis ○ Also occurs with trauma, anticoagulation, or malignancy 904

CLINICAL ISSUES

Natural History & Prognosis • Excellent prognosis for uncomplicated cases treated with prompt surgery ○ Overall mortality from acute cholecystitis is 3% (< 1% in young patients and 10% in high-risk patients) • May progress to gangrenous cholecystitis and perforation if untreated

Treatment • Immediate cholecystectomy in patients who are good surgical candidates ○ Laparoscopic approach preferred: Reduces postoperative pain and shortens hospital stay ○ Delaying surgery increases complications and risk of open conversion due to local inflammation • Percutaneous cholecystostomy with antibiotics in patients who are high-risk surgical candidates ○ Temporary bridge for patients with high operative risk

DIAGNOSTIC CHECKLIST Consider • Perforated duodenal ulcer or pancreatitis when inflammation is primarily centered around duodenum/pancreas with secondary GB wall thickening

SELECTED REFERENCES 1.

2.

Atar E et al: Percutaneous cholecystostomy in critically ill patients with acute cholecystitis: complications and late outcome. Clin Radiol. 69(6):e247-52, 2014 Choi IY et al: Diagnosis of acute cholecystitis: value of contrast agent in the gallbladder and cystic duct on Gd-EOB-DTPA enhanced MR cholangiography. Clin Imaging. 38(2):174-8, 2014

Acute Calculous Cholecystitis Biliary System

(Left) Axial CECT in a patient with right upper quadrant pain demonstrates a thickened, irregular GB wall with adjacent fat stranding , suggesting acute cholecystitis. (Right) Axial fat-suppressed T2WI in the same patient demonstrates the irregularity of the thickened GB wall, with subtle sites of ulceration . This was confirmed to represent gangrenous cholecystitis at surgery.

(Left) Axial CECT demonstrates a thickened, inflamed GB with wall thickening and a small amount of free fluid near the fundus. Most importantly, there is active extravasation within the GB lumen, in keeping with this patient's surgically confirmed hemorrhagic cholecystitis. (Right) Axial CECT shows highdensity blood distending the GB , with similar density blood tracking in Morison pouch and medial to the GB . At surgery, the GB was gangrenous and contained hemorrhagic bile.

(Left) CT scout image in a septic patient with abdominal pain after surgery demonstrates gas filling the GB . There also appears to be a collection of gas more medially . Ureteral stents and surgical clips are noted from the patient's recent surgery. (Right) Axial NECT from the same patient demonstrates findings of emphysematous cholecystitis, with gas in the GB lumen and wall. The fluid/gas tracking outward from the GB, as well as the adjacent gas and fluid collection , are consistent with perforation.

905

Biliary System

Acalculous Cholecystitis KEY FACTS

IMAGING • Ultrasound ○ Findings identical to calculous cholecystitis (except gallstones) ○ Thickening of gallbladder wall > 3 mm ○ Positive sonographic Murphy sign – May be absent or impossible to elicit in critically ill patients at highest risk ○ Gallbladder distention (> 5 cm in transverse plane) ○ Gallbladder wall hyperemia on color Doppler • CT and MR ○ Gallbladder wall thickening (> 3 mm) with mural/mucosal hyperenhancement ○ Dilated gallbladder (> 5 cm) with pericholecystic fluid and fat stranding ○ Hyperenhancement of liver adjacent to gallbladder • Hepatobiliary scintigraphy

(Left) Coronal CECT in a critically ill ICU patient demonstrates severe gallbladder (GB) wall thickening and edema with pericholecystic fat stranding and fluid. Note the lack of clear enhancement of the GB wall near the fundus , concerning for gangrenous cholecystitis. (Right) Coronal CECT acquired a day later shows placement of a cholecystostomy tube ,a common temporizing measure in critically ill patients too unstable for cholecystectomy.

(Left) CECT of a diabetic septic female 4 days post laparotomy for a perforated duodenal ulcer shows a distended GB, wall thickening , and pericholecystic fat infiltration . No gallstones were identified at ultrasound. (Right) Hepatobiliary scan of the same patient shows progressive small bowel filling but no GB activity 30 minutes post tracer administration. No GB activity was shown after morphine administration (an observation that increases exam specificity).

906

○ Nonvisualization of gallbladder 4 hours after injection of radiotracer (or 30 minutes after morphine)

PATHOLOGY • Not associated with obstruction of cystic duct by stones • Most often result of bile stasis and gallbladder ischemia • Typically occurs in critically ill patients (trauma, surgery, sepsis, mechanical ventilation, immunosuppression, etc.)

CLINICAL ISSUES • Higher risk of morbidity/mortality compared to calculous cholecystitis with risk of complications ○ More likely than calculous cholecystitis to present atypically ○ Insidious presentation in critically ill patients and diagnosis is often delayed • Preferred treatment: Cholecystectomy and broad spectrum intravenous antibiotics • Cholecystostomy used as bridge to definitive cholecystectomy in critically ill, unstable patients

Acalculous Cholecystitis

Definitions • Acute inflammation of gallbladder (GB) unrelated to gallstones

IMAGING General Features • Best diagnostic clue ○ Combination of imaging features and clinical history – Ultrasound: Distended GB with wall thickening, pericholecystic fluid, and positive sonographic Murphy sign but no gallstones – Hepatobiliary scintigraphy: Nonvisualization of GB – Typical clinical history: Critically ill patient

Ultrasonographic Findings • Findings identical to acute calculous cholecystitis (except for absence of gallstones) ○ Ultrasound often equivocal due to inability to elicit sonographic Murphy sign in intubated/unconscious patients • Thickening of GB wall > 3 mm ○ Striated appearance of wall is common (no longer thought to be suggestive of gangrenous cholecystitis) • Positive sonographic Murphy sign (pain with insonation over GB that is accentuated with deep breathing) ○ May be absent or impossible to elicit in critically ill ICU patients at highest risk for acalculous acute cholecystitis • GB distention (> 5 cm in transverse plane) • Pericholecystic echogenic fat (due to inflammation) • GB wall hyperemia on color Doppler images • Complications ○ Gangrenous cholecystitis: Asymmetric wall thickening, intraluminal linear membranes, and echogenic material due to sloughed mucosa and irregularity/ulcerations of GB wall – May not be associated with wall hyperemia due to necrosis ○ Emphysematous cholecystitis: Intramural and intraluminal gas with multiple bright echogenic reflectors and "dirty" posterior acoustic shadowing – Champagne sign: Tiny, nonshadowing echogenic foci rising up in real-time from dependent portion of GB ○ Perforated GB: Collapsed GB with discrete wall defect and adjacent pericholecystic fluid collection ± complex fluid in peritoneal cavity – Most common site of perforation is fundus, which can be difficult to visualize in some patients – Sonographic hole sign: Visualization of defect in GB wall is more easily diagnosed on CT ○ Hemorrhagic cholecystitis: Echogenic clot within GB

CT Findings • Imaging findings are identical to acute calculous cholecystitis (except for absence of gallstones) • Uncomplicated acalculous cholecystitis ○ GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement – May be associated with intramural lucency caused by wall edema (subserosal halo sign)

○ Pericholecystic fluid and fat stranding ○ Hyperenhancement of liver adjacent to GB (most apparent in arterial phase) ○ Dilated GB (> 5 cm in diameter) • Complicated acalculous cholecystitis ○ Gangrenous cholecystitis: Hypoenhancement or nonenhancement of portions of GB wall – May be associated with small sites of ulceration or outpouchings in GB wall – Often associated with asymmetric wall thickening – Intraluminal linear strands due to sloughed mucosa ○ Emphysematous cholecystitis: Intramural or intraluminal gas with other findings of cholecystitis ○ Hemorrhagic cholecystitis: High-density blood within GB ± blood in intrahepatic/extrahepatic ducts – May be associated with active extravasation (usually best visualized on arterial phase) ○ GB perforation: Collapsed GB with pericholecystic fluid collection &/or free fluid in peritoneal cavity – Usually fluid collections are directly contiguous with site of nonenhancement in GB wall

Biliary System

TERMINOLOGY

MR Findings • Distended GB with wall thickening, pericholecystic fluid, and surrounding fat stranding • Hyperenhancement of GB wall on T1WI C+ images ± hyperenhancement of adjacent liver surrounding GB fossa (rim sign) ○ Interrupted rim sign with sites of nonenhancement of GB wall in gangrenous cholecystitis

Nuclear Medicine Findings • Hepatobiliary scintigraphy ○ Nonvisualization of GB 4 hours after injection of radiotracer or 30 minutes after morphine – May be associated with rim sign: Increased uptake in liver adjacent to GB fossa due to reactive hyperemia ○ Frequent false positives in critically ill patients due to GB dysfunction, prolonged fasting, hyperalimentation, bile stasis, and sludge – False-positive rate reduced with reimaging after injection of morphine

Imaging Recommendations • Best imaging tool ○ Combination of ultrasound and hepatobiliary scintigraphy – Ultrasound useful as initial screening tool, with hepatobiliary scintigraphy utilized in patients with equivocal ultrasound

DIFFERENTIAL DIAGNOSIS Acute Calculous Cholecystitis • Imaging findings are identical, except for presence of gallstones

Gallbladder Wall Edema • Multiple underlying causes, including cirrhosis, congestive heart failure, ascites, hypoalbuminemia, hepatitis, etc. • Nonspecific finding which is present in many ICU patients due to concurrent comorbidities and illnesses 907

Biliary System

Acalculous Cholecystitis

• Clinical history and additional imaging (hepatobiliary scintigraphy) may be needed to differentiate from acalculous cholecystitis

Hyperplastic Cholecystoses • Adenomyomatosis: Different population with no underlying risk factors and no signs of sepsis or fever • Sites of wall thickening often associated with "comet tail" artifact on ultrasound

Gallbladder Carcinoma • Eccentric GB wall thickening, invasion of adjacent liver, and enlarged regional lymph nodes

AIDS Cholangiopathy • GB wall thickening ± bile duct strictures

PATHOLOGY General Features • Not associated with obstruction of cystic duct or GB neck by stones or sludge ○ Most often due to bile stasis and GB ischemia ○ Rarely GB involved in setting of systemic infection ○ Very rarely due to non-stone-related obstruction of cystic duct (e.g., lymph node, hemobilia, choledochal cyst, etc.) • Pathophysiology ○ Predisposing risk factor(s) bile stasis in GB alteration in chemical composition of bile local inflammatory response in GB wall mucosal injury ○ GB ischemia due to hypotension, dehydration, vasoactive drugs resulting in bile stasis ○ Reperfusion injury after ischemia may also play role • Risk factors (most patients have multiple risk factors) ○ Major trauma and burn injuries ○ Major surgery ( risk for colorectal/gastric surgery) ○ Sepsis, hypotension, and mechanical ventilation ○ Immunosuppression ○ Total parenteral nutrition (TPN) and fasting ○ Diabetes mellitus, coronary artery disease, and end-stage renal disease ○ Childbirth ○ Cholesterol emboli, vasculitis, medications (opioids, etc.) • Common risk factors in pediatric population ○ Dehydration, acute bacterial/viral infection, and enlarged portal lymph node (extrinsic obstruction of cystic duct) • Infections associated with risk of acalculous cholecystitis ○ Campylobacter jejuni, Candida, Clostridium perfringens, Cryptosporidium, cytomegalovirus (CMV), EBV, hepatitis A & B, leptospirosis, Q fever, Salmonella, Vibrio cholera • risk of superimposed infection ○ Typically Escherichia coli, Enterococcus faecalis, Klebsiella, Pseudomonas, Proteus, Bacteroides • AIDS/immunocompromised patients at risk for opportunistic infections ○ Microsporidia, Cryptosporidium, and CMV

Gross Pathologic & Surgical Features • No specific morphological differences between calculous and acalculous cholecystitis (except for absence of stones)

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CLINICAL ISSUES Presentation • Most common signs/symptoms ○ May present similarly to acute calculous cholecystitis: Right upper quadrant pain, fever, leukocytosis ○ More likely than calculous cholecystitis to present atypically • Other signs/symptoms ○ Jaundice (~ 20%) and palpable GB are more common in acalculous cholecystitis ○ Mild in AST/ALT • Clinical profile ○ In critically ill patients, presentation may be insidious and diagnosis is often delayed ○ In more stable patients, presentation is similar to calculous cholecystitis

Demographics • Epidemiology ○ Encompasses < 10% cases of acute cholecystitis ○ Initially described in critically ill patients but can be seen in outpatients with risk factors – In one study, 77% (36/47) of patients were outpatient ○ Acalculous cholecystitis accounts for 50-70% of cases of acute cholecystitis in children

Natural History & Prognosis •

morbidity/mortality compared to calculous cholecystitis with risk (> 40%) of complicated cholecystitis ○ ~ 50% risk of gangrene and ~ 10% risk of perforation ○ Mortality ranges between 10-90% ○ Higher morbidity/mortality partially reflects concurrent illness and is likely much lower in outpatients • Prognosis depends on coexisting medical and surgical conditions and rapidity of diagnosis

Treatment • Preferred treatment: Cholecystectomy (open or laparoscopic) + broad spectrum intravenous antibiotics is definitive treatment • Cholecystostomy: Used as bridge to cholecystectomy in critically ill, unstable patients who are not surgical candidates ○ Prophylactic GB drainage of ICU patients with sepsis and suspicious ultrasound advocated in several series

DIAGNOSTIC CHECKLIST Consider • High degree of suspicion for acalculous cholecystitis in patients with risk factors and unexplained sepsis

SELECTED REFERENCES 1.

2.

Atar E et al: Percutaneous cholecystostomy in critically ill patients with acute cholecystitis: complications and late outcome. Clin Radiol. 69(6):e247-52, 2014 Knab LM et al: Cholecystitis. Surg Clin North Am. 94(2):455-70, 2014

Acalculous Cholecystitis Biliary System

(Left) Axial CECT after myocardial infarction shows a distended GB with pericholecystic fat stranding and reactive thickening of the adjacent colon . Patients recovering from surgical or medical emergencies are at risk for acalculous cholecystitis. (Right) US in an ICU patient 3 weeks after trauma shows a distended GB, sludge, irregular wall thickening, focal perforation , and a complex pericholecystic fluid collection . Acalculous cholecystitis was confirmed at surgery.

(Left) US in an elderly patient with sepsis and hypotension after laparotomy for an incarcerated hernia shows irregular GB wall thickening and a linear echogenic band adjacent to the wall ; features compatible with mucosal sloughing and acalculous, gangrenous cholecystitis. (Right) Sagittal US of the GB in a patient with ulcerative colitis shows asymmetric GB wall edema and no gallstones. A sonographic Murphy sign was elicited. Cholecystectomy revealed gangrenous, acute acalculous cholecystitis.

(Left) Axial CECT in a septic ICU patient demonstrates irregular wall thickening of the GB with a focal site of ulceration . (Right) Axial CECT in the same patient demonstrates irregular, "shaggy" wall thickening of the GB with a focal contained perforation . The appearance is highly suggestive of gangrenous cholecystitis with contained perforation, a diagnosis confirmed at surgery.

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Biliary System

Xanthogranulomatous Cholecystitis KEY FACTS

TERMINOLOGY • Rare inflammatory disorder of gallbladder (GB) characterized by accumulation of lipid-laden macrophages and fibrous tissue

IMAGING • Imaging findings overlap with acute cholecystitis, chronic cholecystitis, and gallbladder carcinoma ○ XGC cannot be confidently distinguished from gallbladder carcinoma radiologically • CT: GB wall may be focally or diffusely thickened ○ Low-attenuation intramural nodules and bands (corresponding to foamy cell infiltrate and abscesses) ○ Pericholecystic fluid and inflammatory change ± fistulous tracts, abscesses, contained perforation, etc. ○ Inflammation can extend to involve adjacent liver and mimic GB cancer with hepatic invasion • MR: Gallbladder wall thickening (diffuse > focal) with intramural T2 hyperintensity

(Left) Resected GB shows marked wall thickening and an intramural abscess . A portion of the adjacent liver was resected because of the high intraoperative suspicion of GB cancer. Pathology revealed xanthogranulomatous cholecystitis (XGC). (Right) Axial CECT shows a thickened wall of the gallbladder, especially the fundus , with an indistinct border with the liver. While the appearance was concerning for gallbladder cancer, this was found to be XGC at cholecystectomy.

(Left) Axial CECT of a patient with RUQ pain shows marked irregular GB wall thickening , intramural low attenuation , and several pericholecystic collections . Low-attenuation intramural nodules in XGC are due to either abscesses or xanthogranulomas. (Right) Axial NECT in a patient with chronic abdominal pain shows a distended, thick-walled gallbladder exhibiting indistinct margins with the liver . While this was worrisome for carcinoma, XGC was confirmed at surgery.

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○ Discrete intramural nodules appear T2 hyperintense and hypointense on T1WI and T1WI C+ ○ Thickened gallbladder wall and intramural nodules may show signal drop-out on out-of-phase images ○ Thickened wall often demonstrates delayed enhancement on T1WI C+ • US: Hypoechoic nodules or bands within thickened GB wall ○ Gallstones, sludge, echogenic intraluminal debris

PATHOLOGY • Mucosal ulceration or rupture of Rokitansky-Aschoff sinuses extravasation of bile into GB wall phagocytosis of bile lipids inflammation and xanthoma cell formation • Gallstones always present and may play causative role

CLINICAL ISSUES • Symptoms most often similar to acute cholecystitis, but can be chronic and mimic malignancy • More common in females during 6th or 7th decade of life • Only definitive treatment is cholecystectomy

Xanthogranulomatous Cholecystitis

Abbreviations • Xanthogranulomatous cholecystitis (XGC)

Synonyms • Fibroxanthogranulomatous cholecystitis; xanthogranulomatous cholangitis

Definitions

•

• Rare inflammatory disorder of gallbladder (GB) characterized by accumulation of lipid-laden macrophages and fibrous tissue

IMAGING

•

General Features

○ Areas of xanthogranulomatosis are iso- or slightly T2 hyperintense ○ Areas of necrosis and abscess are highly T2 hyperintense ○ Discrete intramural nodules (akin to CT) appear T2 hyperintense and hypointense on T1WI and T1WI C+ ○ Thickened gallbladder wall (and intramural nodules) may show subtle signal drop-out on out-of-phase images as a result of intracellular lipid Thickened wall often demonstrates delayed enhancement on T1WI C+ with preservation of continuous mucosal enhancement ○ Gallbladder cancer typically demonstrates earlier peak enhancement Both gallbladder cancer and XGC typically demonstrate restricted diffusion on DWI, but malignancy typically demonstrates lower ADC values Gallstones almost always present (low signal on all pulse sequences) Surrounding infiltration into pericholecystic fat and liver (usually high signal on T2WI)

• Best diagnostic clue ○ GB wall thickening with intramural lowattenuation/hypoechoic nodules or bands corresponding to foamy cell infiltrates or abscesses

•

Imaging Recommendations

Ultrasonographic Findings

• Best imaging tool ○ CECT or MR

• GB wall thickening (may rarely appear focal and mass-like, mimicking carcinoma) • Hypoechoic nodules or bands within GB wall • Echogenic pericholecystic fat (reflecting pericholecystic inflammation) • Gallstones, sludge, echogenic intraluminal debris • Pericholecystic fluid collections • Hypoechoic areas of inflammation in liver adjacent to gallbladder fossa

CT Findings • Imaging findings overlap with acute cholecystitis, chronic cholecystitis, and gallbladder carcinoma ○ GB wall may be focally or diffusely thickened (± loss of normal wall definition) – GB wall may demonstrate poor enhancement ○ Low-attenuation intramural nodules and bands corresponding to foamy cell infiltrate and areas of necrosis/abscess – Intramural nodule may occupy > 60% of wall surface – Most unique imaging feature for XGC ○ Pericholecystic fluid, inflammatory change, and induration ± fistulous tracts, abscesses, contained perforation, etc. – Inflammation can extend to involve adjacent liver (blurring margin between GB and liver), and thus mimic GB cancer with hepatic invasion ○ Adjacent focal hyperperfusion of liver/transient hepatic attenuation difference (THAD) ○ Gallstones almost always present but not always visible on CT ○ Local lymphadenopathy frequent (usually reactive due to inflammation) • Helpful findings to differentiate XGC from GB carcinoma ○ More commonly diffuse wall thickening (rather than focal) ○ Continuous mucosal line of enhancement ○ Intramural low-attenuation nodules ○ Absence of hepatic invasion ○ Absence of biliary dilatation ○ Presence of 3 findings leads to 83% sensitivity, 100% specificity, and 91% accuracy for differentiation of XGC from GB carcinoma

MR Findings

•

Biliary System

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Gallbladder Carcinoma • Soft tissue mass extending from GB wall with invasion of liver and porta hepatis ○ May appear as diffuse or focal wall thickening or discrete polypoid mass • Unlike XGC, frequently results in obstruction of common duct, direct invasion of liver, and bulky periportal lymphadenopathy • In most cases cannot be distinguished from XGC based on imaging alone, and distinction only possible after cholecystectomy • More likely than XGC to present with anorexia, weight loss, palpable mass, and jaundice

Gallbladder Adenomyomatosis • Mural GB wall thickening secondary to exaggeration of Rokitansky-Aschoff sinuses and smooth muscle proliferation ○ Can result in focal/diffuse wall thickening or discrete mass (usually at GB fundus) ○ Echogenic foci in GB wall with "comet tail" artifacts on ultrasound ○ Could theoretically mimic XGC with discrete intramural nodules on CT or MR • Unlike XGC, patients with adenomyomatosis are asymptomatic

• Gallbladder wall thickening (diffuse > focal) with intramural T2 hyperintensity 911

Biliary System

Xanthogranulomatous Cholecystitis

Gangrenous Cholecystitis • Asymmetrically thickened gallbladder wall on US with pericholecystic fluid, ulceration or irregularity of wall, intraluminal linear sloughed membranes, or frank perforation ○ Fat stranding and inflammation of pericholecystic fat on CT/MR with echogenic pericholecystic fat on US • XGC may not be readily distinguishable from acute cholecystitis (either uncomplicated or gangrenous), with both entities often exhibiting similar clinical symptoms

PATHOLOGY General Features • Etiology ○ Pathogenesis – Mucosal ulceration or rupture of Rokitansky-Aschoff sinuses extravasation of bile into GB wall phagocytosis of bile lipids inflammation and xanthoma cell formation ○ Gallstones present in almost all patients and likely plays a causative role – Gallstone obstruction and stasis increased intraluminal pressure mucosal ulceration or rupture of Rokitansky-Aschoff sinuses • Associated abnormalities ○ Proposed association and relationship with GB carcinoma (uncertain) – Gallbladder cancer present in about 6% of cases of XGC ○ Questionable association with cholangiocarcinoma ○ Biliary obstruction (less common than GB cancer)

Staging, Grading, & Classification • Stage I ○ Confined to GB and pericholecystic space • Stage II ○ Involvement of lower biliary tree, duodenum, or colon

Gross Pathologic & Surgical Features • GB wall thickening ○ Xanthogranulomatous foci in GB wall ○ Ulcerated mucosa • Serosa covered with dense fibrous adhesion • Frequent infiltration of surrounding pericholecystic fat and liver • Gallstones (seen in all cases)

Microscopic Features • Abundant lipid-laden macrophages, fibroblasts, acute and chronic inflammatory cells

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Symptoms often acute and similar to acute calculous cholecystitis: RUQ pain, fever, leukocytosis ○ Symptoms can also mimic malignancy, including obstructive jaundice • Other signs/symptoms ○ Symptoms may be chronic and persist for years 912

○ Biliary colic ○ Jaundice (secondary to biliary obstruction) • Laboratory findings ○ WBC ○ bilirubin and alkaline phosphatase (secondary to choledocholithiasis or Mirizzi syndrome)

Demographics • Age ○ Usually 6th or 7th decade of life • Gender ○ F>M • Epidemiology ○ Incidence: 0.7% of symptomatic GB diseases in USA – Reported incidence as high as 10% in Japan and India

Natural History & Prognosis • Active and destructive process that may persist for years and can lead to significant morbidity • High rate of complications (as high as 30%) ○ Perforation ○ Pericholecystic/hepatic abscess ○ Fistula formation to adjacent organs (e.g., colon or duodenum) or skin surface ○ Mirizzi syndrome • Prospective diagnosis is uncommon, and in many cases, diagnosis only made at cholecystectomy, with preoperative diagnosis of either acute cholecystitis or gallbladder carcinoma

Treatment • Only definitive treatment is cholecystectomy ○ Open cholecystectomy is preferred due to extent of inflammation and frequent preoperative suspicion of gallbladder carcinoma ○ Requires complete resection of adjacent xanthogranulomatous tissue and liver (if involved) ○ Requires intraoperative frozen section to differentiate from GB carcinoma

DIAGNOSTIC CHECKLIST Consider • XGC cannot be confidently distinguished from GB carcinoma radiologically and definitive diagnosis is almost always only possible after cholecystectomy

Image Interpretation Pearls • Consider XGC if gallbladder is diffusely thickened with lowattenuation nodules or bands in gallbladder wall (representing xanthogranulomatous inflammation or microabscesses)

SELECTED REFERENCES 1.

Lee NK et al: Diffusion-weighted magnetic resonance imaging for nonneoplastic conditions in the hepatobiliary and pancreatic regions: pearls and potential pitfalls in imaging interpretation. Abdom Imaging. ePub, 2014

Xanthogranulomatous Cholecystitis Biliary System

(Left) Axial CECT of an asymptomatic 75-year-old man shows irregular GB wall thickening and intramural low attenuation . (Right) Ultrasound of the same patient shows asymmetric wall thickening , sludge , and a stone within the GB neck (and focal fatty sparing ). Preoperative differentiation between GB carcinoma and xanthogranulomatous cholecystitis (XGC) is often difficult, but the absence of ductal dilatation may suggest a chronic inflammatory process rather than neoplasia.

(Left) Axial CECT of a 64-yearold woman with chronic right upper quadrant pain shows gallbladder wall thickening as well as focal mural low attenuation . At pathology, the low attenuation corresponded to an area of necrosis filled with foamy macrophages. Note the increased hepatic perfusion, representing a THAD . (Right) Ultrasound of the same patient shows GB wall thickening, multiple small cystic areas of mural necrosis along the anterior wall , and sludge filling the GB lumen .

(Left) Axial CECT of an asymptomatic 88-year-old man performed for aortic aneurysm evaluation shows incidental irregular GB wall thickening and intramural low attenuation . (Right) US of the same patient shows wall thickening , sludge , and intramural hypoechogenicity . Laparoscopic cholecystectomy confirmed chronic XGC. Note that the extensive adhesions and wall thickening associated with chronic inflammation often necessitate open cholecystectomy.

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Biliary System

Emphysematous Cholecystitis KEY FACTS

TERMINOLOGY • Rare form of acute cholecystitis due to secondary infection by gas-forming organism

• Radiography: Insensitive for detection of ectopic gas • MR: Intraluminal and intramural gas appear as signal voids on all pulse sequences

IMAGING

PATHOLOGY

• CT ○ Best modality for identifying intramural/intraluminal gallbladder (GB) gas (100% sensitive) ○ Gas within pericholecystic abscess or free intraperitoneal air may be present with perforation ○ Other CT findings similar to uncomplicated cholecystitis • Ultrasound ○ Gas in GB wall manifests as highly echogenic reflectors with dense posterior acoustic "dirty" shadowing ○ Associated with "ring-down" or "comet tail" artifact ○ Intraluminal gas bubbles rise up to nondependent portions of GB (champagne sign) ○ Cholelithiasis (50%), GB wall thickening, pericholecystic free fluid, and Murphy sign

• Infection of GB with gas-forming organisms such as Clostridium welchii and Escherichia coli • Etiology may reflect vascular compromise of cystic artery • Major contributing factors: Atherosclerosis, diabetes, advanced age, primary infection with gas-forming organism

(Left) Ultrasound image in an elderly diabetic man with fever demonstrates echogenic reflectors in the gallbladder (GB) wall with "dirty" acoustic shadowing and "ring down" artifact , classic for emphysematous cholecystitis. (Right) Axial CECT in a patient with melanoma shows widespread liver metastases . Gas is present within the GB lumen , and the GB wall appears to be perforated . Gangrenous perforation of the GB was seen at surgery, possibly related to the patient's chemotherapy.

(Left) Color Doppler ultrasound in a diabetic patient shows a distended GB containing heterogeneous material, including some foci of very high-intensity echoes within the lumen and wall of the GB, and virtually no flow within the GB wall. (Right) Axial CECT in the same patient shows the distended GB with gas bubbles within the wall and lumen corresponding to the echogenic foci identified on sonography, in keeping with emphysematous cholecystitis.

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CLINICAL ISSUES • Atypical, mild, or insidious presentations (especially in diabetics or elderly) often delay diagnosis and treatment • High risk of gangrene, perforation, and sepsis if untreated, with high mortality rate (15-25%) • Definitive treatment: Urgent cholecystectomy + parenteral antibiotics ○ Cholecystostomy (as bridge to cholecystectomy) in highrisk, poor surgical candidates

Emphysematous Cholecystitis

Definitions • Rare form of acute cholecystitis due to secondary infection by a gas-forming organism

IMAGING General Features • Best diagnostic clue ○ Curvilinear intramural gas or intraluminal gas resulting in a gas-fluid level within the gallbladder (GB) • Size ○ Ranges from several bubbles to extensive intramural or intraluminal gas

Imaging Recommendations • Best imaging tool ○ NECT or CECT ○ Plain radiographs should not be utilized if there is high suspicion for this diagnosis

Radiographic Findings • Radiography ○ Intraluminal (rounded) or intramural (curvilinear) gas in expected position of GB – Air-fluid level may be present in upright or decubitus films ○ Insensitive for detection of emphysematous cholecystitis: Only identified 45% of cases in 1 series – Cases where findings are apparent on radiography tend to be more severe

CT Findings • Best modality for identifying intramural or intraluminal GB gas (100% sensitive) ○ Gas within pericholecystic abscess or free intraperitoneal air may be present with perforation ○ Rarely portal venous gas due to GB wall ischemia ○ Extension of gas into remainder of biliary system suggests severe form of infection • Gallstones seen in only ~ 50% of patients: Acalculous cholecystitis carries higher risk • Other findings are similar to uncomplicated cholecystitis ○ GB wall thickening (> 3 mm) ○ GB distension > 5 cm (in short axis) ○ Pericholecystic free fluid and fat stranding ○ Irregularity, ulcerations, and absent enhancement of GB wall due to gangrene

MR Findings • Intraluminal and intramural gas appear as signal voids on all pulse sequences ○ Floating signal void due to gas bubbles in nondependent portion of GB (unlike stones which are dependent) ○ Low signal intensity rim around margin of GB due to intramural gas ○ Gas causes field inhomogeneity and susceptibility artifact at air-tissue interface • Irregular wall thickening with areas of heterogeneous T1 and T2 hyperintensity indicative of intramural hemorrhagic necrosis • Other findings similar to uncomplicated cholecystitis

○ Low signal (T1WI and T2WI) intensity stones in dependent portion of GB (particularly in neck and cystic duct) ○ Wall thickening (> 3 mm), GB distension (> 5 cm), and pericholecystic fluid

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Gas in GB wall manifests as highly echogenic reflectors with dense posterior acoustic "dirty" shadowing ○ Shadowing is not anechoic (as is seen with gallstones), but is of intermediate echogenicity ○ Echogenic reflectors associated with "ring-down" or "comet tail" artifact • Intraluminal gas bubbles should be mobile on real-time US and may rise up to nondependent portions of GB similar to bubbles of champagne (champagne sign) ○ Gas may change position when patient is moved • Cholelithiasis (in 50% of patients), GB wall thickening, pericholecystic free fluid, and pericholecystic echogenic fat (due to inflammation) • US has high specificity, but lower sensitivity, for detection of emphysematous cholecystitis ○ Echogenic gas in GB lumen may be misinterpreted as gas-filled bowel, stone-filled GB, or porcelain GB

DIFFERENTIAL DIAGNOSIS Gangrenous Cholecystitis • No evidence of ectopic intraluminal or intramural gas • Ultrasound: Asymmetric GB wall thickening, intraluminal membranes and heterogeneous intraluminal material due to sloughed mucosa, and ulcerations of GB wall ○ Sonographic Murphy sign absent in 1/3 of patients • CECT: Hypoenhancement or nonenhancement of portions of GB wall

Gas-Forming Cholangitis • Pneumobilia is very rare finding in ascending cholangitis and may be due to gas-forming organisms or choledochoenteric fistula • Obstructing common duct stone, biliary ductal dilatation, high-density bile, and biliary duct wall thickening suggest cholangitis • GB should appear normal (except for intraluminal gas)

Gas-Forming Hepatic Abscess • Multiloculated, rim-enhancing fluid collection within liver, often with multiple "satellite" abscesses and surrounding low density parenchymal edema • Internal gas within abscess will appear similar to gas elsewhere on US: Bright echogenic reflectors with "dirty" acoustic shadowing

Gas in Biliary Tree from Biliary-Enteric Anastomosis or Post Sphincterotomy • Identification of biliary-enteric anastomosis and clinical history are keys to diagnosis • Pneumobilia and gas in GB are normal findings in this situation and do not imply infection

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Biliary System

Emphysematous Cholecystitis

Retroperitoneal Gas • Gas in retroperitoneum may be secondary to a number of different entities, including perforated duodenal ulcer, emphysematous pyelonephritis, and emphysematous pancreatitis

Gallbladder Filled With Gallstones • GB may not be discretely visualized on US with posterior acoustic shadowing, mimicking gas • Wall-echo-shadow complex and "clean" posterior acoustic shadowing allow distinction between entities

Porcelain Gallbladder • Dense posterior acoustic shadowing on US should be "clean" (unlike "dirty" shadowing with gas) • Calcification along anterior and posterior wall may be visible on US

Bowel Gas in Right Upper Quadrant • Bowel gas near expected position of GB may mimic emphysematous cholecystitis on US • Bowel should demonstrate peristalsis in real time

PATHOLOGY General Features • Etiology ○ Infection of GB with gas-forming organisms such as Clostridium welchii (1/3 of cases) and Escherichia coli – Other common genera: Staphylococcus, Streptococcus, Pseudomonas, Enterococcus, and Klebsiella ○ Secondary infection of GB complicating acute calculous or acalculous cholecystitis ○ Gallstones present in ~ 50% of patients • Pathogenesis is thought to be partially secondary to vascular compromise of cystic artery ○ Contributing factors – Vascular compromise (atherosclerosis of cystic artery) – Cholelithiasis – Impaired immunity (diabetes, advanced age) □ Up to 50% of affected patients are diabetic – Infection with gas-forming organisms (primary or secondary)

Staging, Grading, & Classification • Grading system based on distribution of gas within GB ○ Stage 1: Gas in GB lumen ○ Stage 2: Gas in GB wall ○ Stage 3: Gas in pericholecystic space

Gross Pathologic & Surgical Features

Presentation • Most common signs/symptoms ○ Symptoms similar to uncomplicated cholecystitis in most patients – Right upper quadrant pain, low-grade fever, nausea, vomiting, and leukocytosis ○ Clinical presentation may be atypical, mild, or insidious (especially in diabetic or elderly patients), potentially delaying diagnosis and treatment • Other signs/symptoms ○ Gram-negative septic shock and peritonitis in setting of perforation • Laboratory findings ○ Leukocytosis and mild to moderate hyperbilirubinemia (due to hemolysis induced by clostridial infection)

Demographics • Age ○ 50-70 years • Gender ○ M>F • Epidemiology ○ Includes 1% of all cases of acute cholecystitis ○ More frequent in patients with acalculous cholecystitis ○ More common in patients with diabetes (more prone to clostridial infection) ○ Atherosclerosis with decreased flow in cystic artery may be a contributing factor

Natural History & Prognosis • High risk of gangrene, perforation, and sepsis if untreated ○ Necrosis and gangrene seen in 75% at surgery ○ Perforation seen in 20% of cases (5x higher risk than uncomplicated cholecystitis) • High mortality rate (15-25%) primarily due to high incidence of GB wall gangrene and perforation

Treatment • Urgent cholecystectomy (definitive treatment) ○ Can be performed using laparoscopic or open approach ○ High rate of conversion to open cholecystectomy due to extensive inflammation in GB fossa • Cholecystostomy (as bridge to cholecystectomy) in highrisk, poor surgical candidates • Parenteral antibiotic therapy (adjuvant treatment) • Hypothetical adjuvant role for hyperbaric oxygenation

DIAGNOSTIC CHECKLIST

• Gangrenous and necrotic GB

Consider

Microscopic Features

• Distinguish emphysematous cholecystitis on US from other common mimics, including GB filled with stones, porcelain GB, and bowel gas

• • • • •

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CLINICAL ISSUES

Extensive hemorrhagic necrosis Diffuse edema Cystic spaces in GB wall from gas pockets Intramural abscesses Endarteritis obliterans

SELECTED REFERENCES 1.

Revzin MV et al: The gallbladder: uncommon gallbladder conditions and unusual presentations of the common gallbladder pathological processes. Abdom Imaging. Epub ahead of print, 2014

Emphysematous Cholecystitis Biliary System

(Left) Axial NECT in an elderly diabetic woman demonstrates air within the wall and lumen of the GB, which has a thickened wall. Note the presence of significant surrounding fat stranding and ascites , (Right) Coronal NECT in the same patient demonstrates not only the gas within the GB wall , but also gas extending outside the GB, in keeping with perforation. Emphysematous cholecystitis carries a high risk of both wall gangrene and perforation.

(Left) Ultrasound of a 79-yearold man with right upper quadrant pain shows wall thickening and nondependent linear intramural echogenicity . Note the "dirty" posterior shadowing , an ultrasound artifact characteristic of gas. (Right) Transverse ultrasound of the same patient shows intramural gas and posterior "dirty" shadowing . Note the infiltrated omentum adjacent to the GB and fine, layering gallstones . Gangrenous cholecystitis was confirmed at pathology.

(Left) NECT of an elderly man with coronary artery disease, diabetes, and abdominal pain shows intraluminal and intramural GB gas. Note free intraperitoneal gas ,a manifestation of GB perforation. Transmural GB necrosis and gram-negative rods were shown at pathology. (Right) Longitudinal grayscale ultrasound of the GB in an elderly diabetic patient reveals an edematous wall and intramural gas , characteristic findings in the setting of emphysematous cholecystitis.

917

Biliary System

Mirizzi Syndrome KEY FACTS

TERMINOLOGY • Partial or complete obstruction of common hepatic duct (CHD) due to gallstone impaction in cystic duct, infundibulum, or Hartmann pouch of gallbladder (GB)

IMAGING • ERCP: Extrinsic narrowing of CHD, dilated intrahepatic ducts, and lack of GB opacification ○ Impression on CHD is often concave to the right • MR: Dilated CHD and intrahepatic ducts with stricture at level of stone (signal void on all pulse sequences) ○ Site of CHD narrowing may appear thickened and hyperenhancing due to inflammation on T1WI C+ • US: Large, immobile gallstone impacted in cystic duct or infundibulum with dilated intrahepatic ducts

TOP DIFFERENTIAL DIAGNOSES • Choledocholithiasis

(Left) Graphic of Mirizzi syndrome depicts a large cystic duct stone causing extrinsic compression of the common hepatic duct (CHD) and dilation of the intrahepatic bile ducts . (Right) Coronal T2WI MR shows subtle intrahepatic bile duct dilation and a large gallstone impacted within the neck of the gallbladder (GB), causing extrinsic narrowing of the common duct.

(Left) Coronal CECT shows a cystic duct stone that causes extrinsic compression of the CHD . The intrahepatic ducts were dilated, which was better seen on axial sections (not shown). (Right) Coronal CECT demonstrates a large gallstone in the GB neck compressing the adjacent CHD , resulting in mild intrahepatic biliary dilatation (not shown). Note the dilated GB with multiple stones and mild wall thickening.

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• Cholangiocarcinoma, GB carcinoma, or regional lymphadenopathy • Benign biliary stricture

PATHOLOGY • Impaction of stone in cystic duct, infundibulum, or Hartmann pouch compressing bile duct at same level ○ Obstruction may be due to direct mass effect or development of stricture in CHD due to inflammation • Predisposing factors: Long cystic duct running parallel to CHD or low insertion of cystic duct into common bile duct • Cholecystocholedochal fistula may develop due to chronic inflammation/pressure necrosis, with gallstones eroding from cystic duct into bile duct

CLINICAL ISSUES • Common symptoms: Fever, jaundice, RUQ pain (symptoms of obstructive jaundice, acute cholecystitis, cholangitis) • Definitive treatment is surgical, with approach determined by type of Mirizzi syndrome

Mirizzi Syndrome

Definitions • Partial or complete obstruction of common hepatic duct (CHD) due to gallstone impaction in cystic duct, infundibulum, or Hartmann pouch of gallbladder (GB)

IMAGING General Features • Best diagnostic clue ○ Impacted cystic duct stone causing extrinsic mass effect on CHD with resultant dilatation of intrahepatic ducts • Morphology ○ Smooth extrinsic narrowing of CHD

Radiographic Findings • ERCP ○ Extrinsic narrowing of CHD, dilated intrahepatic ducts, and lack of GB opacification – Extrinsic impression on CHD is often concave to the right due to typical orientation of cystic duct relative to CHD ○ Probably best modality for identifying cholecystocholedochal fistula, with contrast seen to directly pass from dilated biliary tree into GB ○ Accuracy of ERCP for Mirizzi syndrome: 55-90%

MR Findings • MRCP or T2WI can nicely demonstrate gallstones, with 1 stone impacted in GB neck or cystic duct ○ Gallstones usually appear as signal voids on all pulse sequences ○ Dilated CHD proximal to level of stone, discrete stricture or narrowing at level of stone, and more distal bile duct appearing decompressed • Site of stricture or narrowing may appear thickened and hyperenhancing due to inflammation on T1WI C+ ○ May be mistaken for tumor (such as cholangiocarcinoma) • GB often thickened and inflamed due to concomitant cholecystitis • MRCP can also demonstrate anatomic variants that might predispose to Mirizzi syndrome, including low insertion of cystic duct and long cystic duct running parallel to CHD

Ultrasonographic Findings • Large, immobile gallstone impacted in cystic duct or infundibulum with dilated intrahepatic ducts proximal to level of stone • Most patients have multiple other stones in GB • Findings of cholecystitis frequent (GB wall thickening, wall hyperemia on color Doppler, pericholecystic fluid, positive sonographic Murphy sign) ○ GB may be contracted and thickened due to chronic cholecystitis

CT Findings • Imaging findings similar to MR or US, with large stone in cystic duct, focal narrowing of CHD at level of stone, and biliary dilatation upstream from level of stone ○ More difficult to recognize stones on CT than on MR or US, and may be difficult in some cases to distinguish stone from soft tissue mass or tumor

○ If stone is recognized, multiplanar reformats are essential for properly identifying location of stone (within cystic duct rather than CHD) and appreciating mass effect of stone on adjacent common duct • CT may be helpful for identifying other findings that may suggest tumor, including liver metastases, soft tissue mass in porta hepatis, etc.

Biliary System

TERMINOLOGY

Nuclear Medicine Findings • Hepatobiliary scan (HIDA): Nonfilling GB, dilated intrahepatic ducts and CHD, and delayed transit of radiotracer into duodenum

Imaging Recommendations • Best imaging tool ○ US, MRCP, ERCP • Protocol advice ○ Add MRCP sequences to depict stones and better delineate ductal anatomy, location of stone, and mass effect on CHD

DIFFERENTIAL DIAGNOSIS Choledocholithiasis • Small common duct calculi causing obstruction may not be visualized on US or CT but should be visualized on MRCP ○ Localizing a stone correctly (i.e., cystic duct vs. CHD) may be difficult on CT • Level of obstruction usually distal to cystic duct (most commonly at distal common bile duct [CBD])

Cholangiocarcinoma • Small mass in bile duct or focal bile duct wall thickening and hyperenhancement with abrupt irregular narrowing of lumen and proximal biliary dilatation • Delayed enhancement of tumor on CECT or MR • Reactive inflammatory wall thickening and enhancement of common duct at level of obstruction in Mirizzi syndrome can rarely be mistaken for cholangiocarcinoma

Gallbladder Carcinoma • May compress or invade common duct resulting in upstream biliary dilatation • Cross-sectional imaging shows mass arising from GB with local invasion (rather than obstruction of CHD by stone) • Association between GB carcinoma and Mirizzi syndrome reported

Benign Biliary Stricture • Often the sequela of prior cholangitis, choledocholithiasis, or prior intervention • Level of narrowing most often distal to cystic duct, and no evidence of cystic duct stone obstructing common duct

CHD Obstruction Due to Enlarged Regional Nodes • Porta hepatis nodes compress CHD • Distinction with Mirizzi syndrome is usually easily made on MR or CECT

PATHOLOGY General Features • Etiology 919

Biliary System

Mirizzi Syndrome ○ Impaction of stone in cystic duct, infundibulum, or Hartmann pouch compressing bile duct at same level – Hartmann pouch: Bulging of inferior surface of infundibulum – Portion of cystic duct and CHD run parallel to each other within common sheath ○ Obstruction caused by either direct mass effect (extrinsic compression or erosion into bile duct) or secondary development of stricture in CHD due to inflammation from stone – May be a single large stone or multiple small stones – Cholecystocholedochal fistula develops due to chronic inflammation and pressure necrosis, with gallstones eroding from cystic duct into bile duct – Predisposing factors include long cystic duct running parallel to CHD, tortuous cystic duct, or low insertion of cystic duct into CBD • Associated abnormalities ○ Acute or chronic cholecystitis – GB often appears atrophic and thickened due to multiple repetitive bouts of acute cholecystitis ○ May have cholecystocholedochal fistula ○ Reported association with GB carcinoma – GB cancer may be identified in up to 25% of cases of Mirizzi syndrome – Some authors recommend intraoperative frozen section of GB

Staging, Grading, & Classification • Csendes classification (1989) ○ Type I (~ 60% of cases): Extrinsic compression of CHD due to cystic duct stone ○ Type II (~ 25% of cases): Cholecystocholedochal fistula involving < 1/3 circumference of ductal wall ○ Type III (~ 13% of cases): Cholecystocholedochal fistula involving 1/3-2/3 circumference of ductal wall ○ Type IV (~ 3% of cases): Cholecystocholedochal fistula with involvement of entire ductal wall circumference ○ Type V was added in 2007: Any Mirizzi type (I-IV) with development of cholecystoenteric fistula • McSherry classification (1982) ○ Type I: Extrinsic compression and obstruction of CHD by stone in cystic duct or Hartmann pouch ○ Type II: Presence of cholecystocholedochal fistula

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Fever, jaundice, right upper quadrant (RUQ) pain – May present initially with symptoms of obstructive jaundice or acute cholecystitis, cholangitis, or pancreatitis – Symptoms may be fulminant or episodic ○ Most patients have longstanding history of gallstone disease ○ Very difficult diagnosis based on clinical symptoms, and diagnostic accuracy in pre-ERCP era was as low as 8% – Over 50% of cases are diagnosed at surgery • Lab findings: alkaline phosphatase, bilirubin ○ CA19-9 may be elevated in Mirizzi syndrome even in absence of malignancy 920

Demographics • Age ○ > 40 years (usually 5th-7th decades of life) • Gender ○ Female predominance (M:F = 1:2) • Epidemiology ○ Reflects prevalence of gallstones ○ Seen in 0.7-1.8% of cholecystectomies ○ May have higher incidence in populations with increased rates of cholelithiasis (including 2.7% in Native Americans)

Natural History & Prognosis • Jaundice and cholangitis, if not treated promptly

Treatment • Stent placement during ERCP may be temporary option prior to surgery but is not definitive therapy ○ May obviate need for CBD exploration at surgery • Definitive treatment is surgical, with approach determined by type of Mirizzi syndrome ○ Type I: Partial or total cholecystectomy without CBD exploration – Although laparoscopic resection is theoretically possible, high rate of conversion to open cholecystectomy ○ Type II: Subtotal cholecystectomy, surgical repair of fistula (suture repair, choledochoplasty), and exploration of CBD ○ Type III: Subtotal cholecystectomy or biliary reconstruction with biliary-enteric anastomosis ○ Type IV: Biliary reconstruction, usually Roux-en-Y hepaticojejunostomy

DIAGNOSTIC CHECKLIST Consider • Distinguish Mirizzi syndrome from malignant biliary obstruction including cholangiocarcinoma, GB carcinoma, or extrinsic adenopathy

Image Interpretation Pearls • Stone impacted in cystic duct causing obstruction of the CHD with upstream intrahepatic biliary dilatation • Differentiate stones in the GB neck or cystic duct from stones in CHD

SELECTED REFERENCES 1.

2. 3. 4. 5.

Katabathina VS et al: Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization. Radiographics. 34(3):565-86, 2014 Luu MB et al: Unusual complications of gallstones. Surg Clin North Am. 94(2):377-94, 2014 Patel NB et al: Multidetector CT of emergent biliary pathologic conditions. Radiographics. 33(7):1867-88, 2013 Cui Y et al: Appraisal of diagnosis and surgical approach for Mirizzi syndrome. ANZ J Surg. 82(10):708-13, 2012 Gupta M et al: Mirizzi syndrome: recognition on magnetic resonance cholangiopancreatography. Clin Gastroenterol Hepatol. 10(12):A32, 2012

Mirizzi Syndrome Biliary System

(Left) Axial CECT shows a dilated GB with a thickened wall and pericholecystic stranding, suggesting acute cholecystitis. (Right) ERCP in the same patient shows that the GB is obstructed by a large gallstone (not visualized by CT). In addition, mass effect from the large cystic duct stone on the adjacent CHD causes intrahepatic biliary dilation , in keeping with Mirizzi syndrome.

(Left) MRCP shows marked intrahepatic ductal dilatation and an abrupt transition to a small-caliber common duct . There is the suggestion of a discrete filling defect in the CHD at the site of transition. (Right) ERCP in the same patient shows intrahepatic ductal dilatation and an obstructing filling defect within the common duct (CD) . Note nonfilling of the GB. A cholecystocholedochal fistula and a large stone at the cystic duct-CD junction were shown at surgery, in keeping with Mirizzi syndrome.

(Left) Sagittal US of the GB neck demonstrates an impacted stone with dilation of the adjacent CHD , compatible with Mirizzi syndrome. (Right) ERCP cholangiogram shows dilated intrahepatic ducts due to a stricture of the CHD . Note the presence of multiple gallstones within the GB . Although not visible on this image, a stone was found impacted in the cystic duct, resulting in Mirizzi syndrome.

921

Biliary System

Hyperplastic Cholecystoses KEY FACTS

TERMINOLOGY • Idiopathic, nonneoplastic, and noninflammatory proliferative disorder that results in GB wall thickening ○ Adenomyomatosis: Mural GB wall thickening due to formation of intramural diverticula (Rokitansky-Aschoff sinuses) with smooth muscle and epithelial proliferation ○ Cholesterolosis: Deposition of foamy, cholesterol-laden histiocytes in subepithelium of GB

IMAGING • Adenomyomatosis ○ US: Focal, segmental, or diffuse wall thickening with anechoic intramural spaces, intramural echogenic foci ± acoustic shadowing, "comet tail" artifacts, & twinkle artifact ○ MR: High-signal cystic spaces (with curvilinear arrangement) on T2WI/MRCP within focally or diffusely thickened GB wall (string of beads or pearl necklace sign)

(Left) Schematic drawing of adenomyomatosis illustrates a thickened gallbladder (GB) wall with multiple intramural cystic spaces . (Right) Ultrasound of an elderly woman with right upper quadrant pain shows tiny echogenic foci within the anterior wall of the GB and posterior "comet tail" artifacts . This appearance is likely caused by reverberation of the ultrasound pulse within cholesterol crystals in the GB subepithelium.

(Left) Ultrasound image demonstrates diffuse thickening of the GB wall with numerous foci of "comet tail" artifact , classic for adenomyomatosis. Note the presence of a gallstone , found in 90% of cases. (Right) Color Doppler ultrasound demonstrates "twinkle" artifact associated with the echogenic reflectors within the thickened GB wall. "Comet tail" and twinkle artifacts are due to reverberation within cholesterol deposited within epithelial penetrations (Rokitansky-Aschoff sinuses).

922

○ CT: Segmental/diffuse GB wall thickening (may present as fundal enhancing soft tissue nodule) – Cystic nonenhancing spaces within thickened GB wall • Cholesterolosis ○ US: Multiple small (< 10 mm) nonshadowing iso/hyperechoic polyps with "comet tail" & twinkle artifact ○ MR: Small, round polyps with intermediate T1/T2 signal

CLINICAL ISSUES • Virtually always asymptomatic, but may very rarely present with RUQ pain • Almost always an incidental finding with no significance ○ Must be correctly differentiated from malignancy based on imaging appearance ○ Adenomyomatosis may rarely require cholecystectomy if symptomatic or if imaging findings are equivocal and there is concern for GB carcinoma ○ Cholesterol polyps may be resected when large or when growth is documented

Hyperplastic Cholecystoses

Synonyms • Cholesterolosis: Strawberry gallbladder (GB), cholesterol polyp • Adenomyomatosis: GB diverticulosis, cholecystitis glandularis proliferans, adenomyomatous hyperplasia

Definitions • Idiopathic, nonneoplastic, and noninflammatory proliferative disorder that results in GB wall thickening ○ Subclassified into 2 entities ○ Adenomyomatosis – Mural GB wall thickening due to exaggeration of normal luminal epithelial folds and formation of intramural diverticula (Rokitansky-Aschoff sinuses) in conjunction with smooth muscle and GB epithelial proliferation ○ Cholesterolosis – Deposition of foamy, cholesterol-laden histiocytes in subepithelium of GB – Numerous small accumulations (strawberry GB) or larger polypoid deposit (cholesterol polyp)

IMAGING General Features • Best diagnostic clue ○ Adenomyomatosis – Focal (typically fundal) or diffuse GB wall thickening with intramural cystic spaces containing echogenic foci and "comet tail" artifacts ○ Cholesterolosis – Echogenic GB polyps with associated "comet tail" artifact • Location ○ Cholesterolosis: Superficial GB wall (epithelium) ○ Adenomyomatosis: Deep GB wall (muscular layer) – Fundal (most common), segmental mid-body ("hourglass" configuration of GB), or diffuse • Size ○ Cholesterol polyps typically 5-10 mm

CT Findings • Adenomyomatosis ○ Segmental or diffuse GB wall thickening – May present as fundal enhancing soft tissue nodule ○ Cystic nonenhancing spaces (Rokitansky-Aschoff sinuses) within thickened GB wall (usually within fundal mass) – Cystic spaces most important feature to differentiate adenomyomatosis from GB carcinoma – Ancillary findings favoring adenomyomatosis: Smooth borders without evidence of biliary ductal dilatation, hepatic invasion, or regional adenopathy ○ Often brisk wall enhancement post contrast • Cholesterolosis: Subepithelial cholesterol and small cholesterol polyps usually imperceptible on CT

MR Findings • Cholesterolosis ○ Small, round, intraluminal polyps juxtaposed against low T1WI signal and high T2WI signal bile

– Nodules are homogeneous and of intermediate signal intensity on both T1WI and T2WI • Adenomyomatosis ○ T1-hypointense foci within thickened GB wall corresponding to bile-filled intramural diverticula – Occasionally T1-hyperintense due to inspissated bile/debris within Rokitansky-Aschoff sinuses ○ T2WI/MRCP high signal cystic spaces (with a curvilinear arrangement) within focally or diffusely thickened GB wall (string of beads or pearl necklace sign) ○ Cystic spaces show no enhancement on T1WI C+ images ○ Diffusion weighted imaging (DWI) not a reliable means of distinguishing cancer from adenomyomatosis

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Grayscale ultrasound ○ Adenomyomatosis – Focal, segmental, or diffuse wall thickening □ Focal or localized form the most common, usually affecting GB fundus □ Segmental form causes annular thickening of GB wall, resulting in strictures: Annular thickening in GB mid body results in "hourglass" appearance □ Diffuse form results in wall thickening of entire GB – Anechoic intramural spaces (Rokitansky-Aschoff sinuses) within thickened portions of GB wall – Intramural echogenic foci ± acoustic shadowing or reverberation ("comet tail") artifacts □ Echogenic foci correspond to small intramural diverticula containing sludge, stones, cholesterol, or papillary projections □ Leads to "diamond ring" appearance (echogenic foci surrounded by anechoic cystic spaces) – US has sensitivity of 80% and specificity of 86% for diagnosis of adenomyomatosis ○ Cholesterolosis – Multiple small (< 10 mm) nonshadowing iso- to hyperechoic nonmobile polyps – "Comet tail" artifact posterior to echogenic foci (cholesterol) within GB wall – No associated posterior acoustic shadowing – Background GB wall is usually normal thickness • Color Doppler ○ Adenomyomatosis – Twinkle artifact posterior to echogenic foci within intramural diverticula □ Rapidly fluctuating mixture of Doppler signals (red and blue pixel) caused by strongly reflecting granular interface and narrow band of intrinsic US machine noise □ Twinkle artifacts usually more prominent at low color Doppler frequencies – Unlike malignancy, no color Doppler vascularity within regions of wall thickening ○ Cholesterolosis – Twinkle artifact caused by focal cholesterol deposits within GB wall

Radiographic Findings • Oral cholecystogram ○ Adenomyomatosis: "Pearl necklace" GB with multiple contrast-filled intramural diverticula 923

Biliary System

Hyperplastic Cholecystoses

Imaging Recommendations

Gross Pathologic & Surgical Features

• Best imaging tool ○ Adenomyomatosis: Ultrasound, MR/MRCP – High-resolution, high-frequency transducer helpful for optimal visualization of GB fundus (most common location for adenomyomatosis) ○ Cholesterolosis: Ultrasound

• Focal/diffuse GB wall thickening without inflammatory changes • Adenomyomatosis: Herniation of bile-containing cystic spaces (Rokitansky-Aschoff sinuses) into GB muscularis propria • Cholesterolosis: Yellow deposits in GB ("strawberry" GB)

DIFFERENTIAL DIAGNOSIS Chronic Cholecystitis

Presentation

• Small contracted GB with generalized wall thickening and gallstones, but no mural "comet tail" artifact

• Most common signs/symptoms ○ Virtually always asymptomatic, but may very rarely present with RUQ pain

Gallbladder Carcinoma • Most frequently presents as polypoid mass > 2 cm or irregular, asymmetric GB wall thickening • Frequently associated with regional adenopathy, biliary ductal obstruction, and hepatic invasion • Usually internal Doppler color flow vascularity • No intramural cystic spaces or "comet tail"/twinkle artifacts • Segmental or focal forms of adenomyomatosis may be difficult to distinguish from GB cancer

Xanthogranulomatous Cholecystitis • Inflammatory process with accumulation of lipid-laden macrophages and inflammatory cells within GB wall • Results from rupture of Rokitansky-Aschoff sinuses and extravasation of bile into GB wall xanthoma formation • Gallstones present in all cases • GB wall thickening with intramural hypodense nodules/bands and pericholecystic inflammation/fluid

Adenomatous Polyp • Benign solitary polyp most often measuring 5-15 mm ○ Risk of malignancy relates to polyp size • No "comet tail" or twinkle artifact

Phrygian Cap • Normal variant with folding of GB fundus, which might mimic focal fundal adenomyomatosis with cystic spaces

PATHOLOGY

924

CLINICAL ISSUES

Demographics • Gender ○ Adenomyomatosis more common in females (F:M = 3:1) ○ No gender predilection in cholesterolosis • Epidemiology ○ Adenomyomatosis identified in 2-9% of resected GBs ○ Cholesterolosis prevalence of 9-26% in cholecystectomy specimens – Cholesterol polyps account for 60-90% of all GB polyps

Natural History & Prognosis • Usually incidental finding of no clinical importance • Must be correctly differentiated from malignancy based on imaging appearance

Treatment • Adenomyomatosis: No treatment in asymptomatic patients where diagnosis is certain ○ Cholecystectomy if symptomatic or if imaging findings are equivocal and there is concern for GB carcinoma • Cholesterol polyps: Although benign, nonspecific appearance often prompts intervention; may be resected when large or when growth documented ○ Management strategies (surveillance and size threshold for resection) are controversial

DIAGNOSTIC CHECKLIST

General Features

Consider

• Etiology ○ Idiopathic and acquired, but exact etiology not understood – Adenomyomatosis postulated to be related to chronic mechanical obstruction of GB or chronic GB inflammation – Cholesterolosis postulated to be related to altered hepatic cholesterol synthesis or abnormal cholesterol transport out of mucosa • Associated abnormalities ○ Gallstones in up to 90% of cases of adenomyomatosis and 50% of cases of cholesterolosis ○ Coexistence of GB carcinoma with adenomyomatosis (especially segmental form) questioned, but now generally not considered to be premalignant

• Differentiate focal or segmental forms of adenomyomatosis from GB malignancy

Image Interpretation Pearls • Look for "comet tail" reverberation artifacts on US within thickened GB wall

SELECTED REFERENCES 1.

2. 3.

Revzin MV et al: The gallbladder: uncommon gallbladder conditions and unusual presentations of the common gallbladder pathological processes. Abdom Imaging. Epub ahead of print, 2014 Nguyen MS et al: Adenomyomatosis. Ultrasound Q. 29(3):215-7, 2013 Pellino G et al: Stepwise approach and surgery for gallbladder adenomyomatosis: a mini-review. Hepatobiliary Pancreat Dis Int. 12(2):13642, 2013

Hyperplastic Cholecystoses Biliary System

(Left) Ultrasound of a patient with vague abdominal pain shows annular wall thickening of the mid body of the GB. Note the presence of intramural diverticula and echogenic foci in this pathologically confirmed example of segmental adenomyomatosis. (Right) MRCP in the same patient shows an "hourglass" deformity of the GB and several adjacent intramural diverticula . Common bile duct dilatation and clinical suspicion of intermittent choledocholithiasis prompted cholecystectomy.

(Left) Ultrasound of an elderly woman shows an incidental, partially cystic mass arising from the GB fundus . Echogenic foci within the lesion are associated with "comet tail" artifact, characteristic of adenomyomatosis. (Right) Ultrasound shows "comet tail" artifact and several minute, echogenic GB polyps . Pathology showed cholesterolosis and hyperplastic (cholesterol) polyps.

(Left) Axial CECT demonstrates tiny internal cystic spaces within a thickened portion of the GB fundus. (Right) Coronal MIP MRCP in the same patient demonstrates multiple cystic spaces in the GB fundus corresponding to the findings on CT. Both the CT and MR appearance is classic for adenomyomatosis, a benign finding that does not require follow-up or treatment.

925

Biliary System

Porcelain Gallbladder KEY FACTS

TERMINOLOGY • Calcification of gallbladder (GB) wall

TOP DIFFERENTIAL DIAGNOSES

IMAGING

• Large gallstone or gallstones filling GB • Emphysematous cholecystitis • Iatrogenic high-density material in GB

• Ultrasound ○ Echogenic curvilinear structure in GB fossa with dense acoustic shadowing – Clean posterior acoustic shadowing (no echogenic foci or "dirty" shadowing to suggest emphysema) – Wall-echo-shadow complex not seen (unlike stones) ○ Biconvex curvilinear calcification of GB wall with visualization of posterior wall of GB – Posterior GB wall not visualized with stones or emphysematous cholecystitis ○ Coarse foci of calcification in GB wall with acoustic shadowing • CT ○ Calcifications in GB wall can be thin or thick and irregular – May involve entire wall or just a segment

(Left) Transverse transabdominal ultrasound shows a curvilinear echogenic structure in the gallbladder (GB) fossa with acoustic shadowing , characteristic of a porcelain GB. (Right) Ultrasound shows increased echogenicity throughout the GB wall and a mass within the fundus. The posterior GB wall is visible, unlike a GB filled with stones or emphysematous cholecystitis. Chronic cholecystitis, intramural calcification, and GB adenocarcinoma were identified at pathology.

(Left) Axial CECT shows partial calcification of the GB wall . Note the subtle soft tissue density within the GB and the blurred margin with the adjacent liver. (Right) Axial CECT in the same patient demonstrates a discrete mass in the GB invading the liver, a classic appearance for GB cancer. GB cancer is thought to be more likely with interrupted, partial GB wall calcification than with diffuse calcification.

926

○ CT is most sensitive modality for identifying calcification

CLINICAL ISSUES • Most common in elderly female patients who are usually asymptomatic • Traditionally thought to be associated with high risk of cancer, but recent studies suggest much weaker association (as low as 6%) • Risk of GB cancer may depend on pattern of calcification, although evidence for this is limited ○ Diffuse intramural calcification: Likely no risk of cancer ○ Flecks of calcium in GB mucosa: risk of cancer • Decision to operate depends on patient age, symptoms, morphology of calcification (diffuse vs. selective), and patient functional status

Porcelain Gallbladder

PATHOLOGY

Definitions

General Features

• Calcification of GB wall

• Etiology ○ Uncertain pathogenesis, but several theories – Intermittent obstruction of GB supersaturation of bile accumulation of calcium carbonate precipitation in wall – Intramural hemorrhage from chronic cholecystitis mural calcification – Dystrophic mural calcification related to chronic inflammation of GB wall due to gallstones • Associated abnormalities ○ Gallstones or milk of calcium bile (95% of cases) ○ GB carcinoma (association weaker than previously thought)

IMAGING General Features • Best diagnostic clue ○ Curvilinear rim of calcification in right upper quadrant (RUQ) conforming to shape of GB • Morphology ○ 2 patterns – Selective mucosal calcification: risk of malignancy – Diffuse intramural calcification: risk of malignancy

Radiographic Findings • Radiography ○ Curvilinear or granular calcification in GB wall ○ May involve entire wall or just a segment

CT Findings • Calcification in GB wall can be thin or thick and irregular ○ May involve entire wall or just a segment • CT is most sensitive modality for identifying calcification

Ultrasonographic Findings • Several different possible appearances ○ Echogenic curvilinear structure in GB fossa with dense acoustic shadowing – Clean posterior acoustic shadowing (no echogenic foci or "dirty" shadowing to suggest GB emphysema) – Wall-echo-shadow complex is not seen (unlike stones filling GB) ○ Biconvex curvilinear calcification of GB wall with visualization of posterior wall of GB – Posterior GB wall not visualized in GB filled with stones or emphysematous cholecystitis ○ Coarse foci of calcification in GB wall with acoustic shadowing

Imaging Recommendations • Best imaging tool ○ CT

DIFFERENTIAL DIAGNOSIS Large Gallstone or Gallstones Filling GB • Can be very difficult to distinguish from porcelain GB on US • Wall-echo-shadow complex characteristic of stones • Visualization of posterior GB wall suggests porcelain GB (rather than stones)

Biliary System

TERMINOLOGY

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Almost always asymptomatic ○ Symptoms (RUQ pain or palpable mass) with development of malignancy or gallstones

Demographics • Age ○ Peak occurrence in 6th decade; mean = 54 years • Gender ○ M:F = 1:5 • Epidemiology ○ Rare: 0.06-0.08% of autopsies; 0.15% of cholecystectomy specimens

Natural History & Prognosis • Incidence of cancer in porcelain GB usually quoted as 1262% based on retrospective data from 1950s-60s; however, more recent reviews suggest weaker association • Recent systematic review of literature with meta-analysis suggests risk of malignancy may be as low as 6% • Risk of GB cancer may depend on pattern of calcification, although evidence for this is limited ○ Diffuse intramural calcification: Likely no risk of cancer ○ Flecks of calcium in GB mucosa: Significant risk of cancer

Treatment • Decision to operate depends on patient age, symptoms, and morphology of calcification (diffuse vs. selective) • Prophylactic cholecystectomy ○ Open approach often advocated, but laparoscopic resection possible, particularly given low risk of GB carcinoma

Emphysematous Cholecystitis • Echogenic crescent in GB fossa with "dirty" acoustic shadowing and ring-down artifact (from gas) on ultrasound can mimic GB wall calcification • CT can best distinguish gas from calcium

SELECTED REFERENCES 1.

Revzin MV et al: The gallbladder: uncommon gallbladder conditions and unusual presentations of the common gallbladder pathological processes. Abdom Imaging. ePub, 2014

Iatrogenic High-Density Material in GB • Iodized oil in GB wall following hepatic chemoembolization • Vicarious excretion of high-density contrast into GB following intravenous contrast administration 927

Biliary System

Milk of Calcium Bile KEY FACTS

• High-density calcium carbonate precipitate within gallbladder (GB) lumen

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Radiography ○ Opacification of GB with high-density, radiopaque fluid – Fluid-fluid level on upright film ○ Rarely opacification of cystic duct or common bile duct (CBD) – Exclamation sign: Coexisting milk of calcium bile and gallstones in CBD • CT: High-attenuation (> 150 HU) sediment • MR: Low signal on T2WI and layers dependently ○ Differentiate from gallstones which are discrete nodules with low T2WI signal • Ultrasound ○ Mixed echogenicity, layering material within GB which might cause acoustic shadowing

• • • •

(Left) Frontal radiograph demonstrates extensive milk of calcium bile filling the gallbladder (GB) . (Right) Specimen radiograph in the same patient after cholecystectomy demonstrates milk of calcium bile in both the GB and cystic duct .

(Left) Ultrasound shows diffuse low-level echo sludge within the GB lumen with posterior acoustic shadowing . Sludge and shadowing were not present on an ultrasound performed 6 months later. (Right) Axial CECT shows high-density milk of calcium bile filling the GB lumen. The GB also demonstrates subtle wall calcification and a gallstone . There is a frequent association of gallstones and milk of calcium bile.

928

○ Echogenicity slightly higher than typical sludge, but may be indistinguishable from sludge if no shadowing ○ May have associated gallstones

TERMINOLOGY

Vicarious excretion of contrast GB sludge Porcelain GB GB hemorrhage

PATHOLOGY • Etiology: Chronic cystic duct obstruction with resultant biliary stasis

CLINICAL ISSUES • Incidental finding which may be asymptomatic • Most patients have symptoms of biliary colic • Associated with complications similar to cholelithiasis ○ Acute cholecystitis, pancreatitis, obstructive jaundice • Cholecystectomy only for symptomatic patients

Milk of Calcium Bile

Porcelain Gallbladder

• Limy bile syndrome, calcium carbonate bile

• Diffuse or focal calcification of GB wall with posterior acoustic shadowing on US • Associated with increased risk of GB carcinoma

Definitions

Gallbladder Hemorrhage

• High-density calcium carbonate precipitate within gallbladder (GB) lumen

• High-attenuation (> 30 HU) fluid in GB • Echogenic on ultrasound without acoustic shadowing ○ May not be easily distinguishable from sludge on US

Synonyms

IMAGING General Features • Best diagnostic clue ○ High-density layering liquid/sediment within GB

Radiographic Findings • Radiography ○ Opacification of GB with high-density, radiopaque fluid – Fluid-fluid level on upright film ○ Less commonly, opacification of cystic duct &/or common bile duct – Always occurs in patients who also have milk of calcium bile in GB – Exclamation sign: Coexisting milk of calcium bile and gallstones in common bile duct

CT Findings • NECT ○ High-attenuation (> 150 HU) sediment in GB (rarely in cystic duct and common bile duct)

MR Findings • Calcium carbonate layers dependently in GB and shows low T2WI signal ○ Differentiate from gallstones, which appear as discrete nodules of low T2WI signal

Ultrasonographic Findings • Mixed echogenicity material within GB which might cause acoustic shadowing ○ Echogenicity slightly higher than typical sludge, but may be indistinguishable from sludge if no shadowing • May have associated gallstones (including chronically obstructing stones in GB neck or cystic duct)

Nuclear Medicine Findings • Hepatobiliary scintigraphy ○ Nonfilling of GB if cystic duct is obstructed

Imaging Recommendations • Best imaging tool ○ NECT

DIFFERENTIAL DIAGNOSIS Vicarious Excretion of Contrast • Hepatic excretion of iodinated contrast • Can be a normal finding on CT, but tends to be most conspicuous in patients with renal failure

Gallbladder Sludge • Layering, mobile, avascular echogenic material without posterior acoustic shadowing ○ May appear mass-like (tumefactive sludge)

Biliary System

TERMINOLOGY

PATHOLOGY General Features • Etiology ○ Chronic cystic duct obstruction with resultant biliary stasis ○ May be associated with long-term total parenteral nutrition (TPN) • Associated abnormalities ○ Cholelithiasis (60-100% of cases in different series) ○ Chronic cholecystitis often present, but likely secondary finding that is not true cause of milk of calcium bile

Gross Pathologic & Surgical Features • Semi-solid, paste-like material almost completely composed of calcium carbonate

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ May be asymptomatic ○ Most patients have biliary colic similar to cholelithiasis: Intermittent RUQ pain • Other signs/symptoms ○ Fever and jaundice as result of biliary obstruction • Clinical profile ○ May be associated with many complications commonly seen with cholelithiasis – Acute cholecystitis, pancreatitis, obstructive jaundice, cholangitis

Demographics • Age ○ Usually middle-aged adults (very rare in children) • Gender ○ F>M • Epidemiology ○ Found in 0.1-1.7% of cholecystectomy specimens

Treatment • No treatment in asymptomatic patients • Cholecystectomy for symptomatic patients

SELECTED REFERENCES 1. 2. 3.

Ballas KD et al: Limy bile syndrome: review of seven cases. ANZ J Surg. 75(9):787-9, 2005 Itoh H: Management of limy bile syndrome: no therapy, laparotomy or endoscopic treatment? Intern Med. 42(1):1-2, 2003 Tsukamoto T et al: Limy bile: a case of obstructive jaundice and review of 26 cases. Osaka City Med J. 49(2):67-70, 2003

929

Biliary System

Autoimmune (IgG4) Cholangitis KEY FACTS

TERMINOLOGY • IgG4-related sclerosing disease: Spectrum of disorders characterized by tumor-like lymphoplasmacytic infiltration and varying degrees of fibrosis in different organs • IgG4-related sclerosing cholangitis: Biliary manifestations of IgG4-related sclerosing disease frequently associated with autoimmune pancreatitis

IMAGING • ERCP:Strictures can involve any portion of the biliary tree, but distal common bile duct (CBD) strictures are most common ○ Strictures long and smooth without irregularity and may cause proximal biliary dilatation • MR: MRCP images nicely demonstrate irregularity and strictures of intrahepatic or extrahepatic bile ducts (most commonly affecting distal CBD) ○ Affected segments demonstrate concentric ductal wall thickening with hyperenhancement on T1WI C+

(Left) CECT of a jaundiced patient shows a thickened, slightly dilated common bile duct (CBD) and an enlarged, sausage-shaped pancreas . The appearance of the pancreas is consistent with autoimmune pancreatitis (AIP), and an elevated IgG4 indicates that the bile duct thickening is due to IgG4related sclerosing cholangitis (ISC). (Right) ERCP in same patient shows a stricture of the distal CBD, the most common manifestation of ISC. ISC and AIP resolved after steroid and azathioprine therapy.

(Left) Coronal CECT in a patient with known autoimmune pancreatitis (not shown) demonstrates tapered narrowing of the distal CBD with wall hyperenhancement, compatible with autoimmune cholangitis. (Right) Coronal CECT in a patient with known autoimmune pancreatitis demonstrates wall thickening, hyperenhancement, and narrowing of the CBD with proximal biliary dilatation , in keeping with IgG4-related cholangitis.

930

• CT:Circumferential focal or diffuse bile duct wall thickening with hyperenhancement of affected segments

PATHOLOGY • Frequently associated with imaging findings of autoimmune pancreatitis and other manifestations of IgG4related sclerosing disease • Exact pathophysiology not well understood, but some evidence for both autoimmune and allergic mechanisms

CLINICAL ISSUES • Typically affects middle-aged and elderly males • Diagnosis based on a combination of imaging, histopathology, serologic ( IgG4) markers and clinical response to steroids/azathioprine • May improve spontaneously, progress, or relapse, although relapse rate after therapy may be high (> 50%) • Treatment with steroids typically effective, although other immunomodulators utilized in refractory cases

Autoimmune (IgG4) Cholangitis

Synonyms • IgG4-related sclerosing disease (IRSD), IgG4-related sclerosing cholangitis (ISC)

Definitions • IRSD: Spectrum of disorders characterized by tumor-like lymphoplasmacytic infiltration and varying degrees of fibrosis in different organs ○ Pancreas is most commonly affected organ (autoimmune pancreatitis) followed by salivary glands and biliary tree • ISC: Biliary manifestations of IRSD frequently associated with autoimmune pancreatitis (AIP) ○ Manifested as wall thickening and biliary strictures

IMAGING

• No clear association between ISC and malignancy, but involved sites in biliary tree may rarely appear mass-like and mimic malignancy (inflammatory pseudotumor) • Diffuse gallbladder wall thickening (due to either lymphoplasmacytic infiltration and transmural fibrosis or superimposed cholecystitis) • Findings of concomitant autoimmune pancreatitis ○ Focal, multifocal, or diffuse (sausage-shaped) pancreatic enlargement with hypodense pancreatic capsule ○ Enlargement of pancreas with a paucity of peripancreatic inflammation, fluid, or stranding ○ Less enhancement than expected in arterial phase; parenchyma/capsule may show delayed enhancement ○ Diffuse or segmental narrowing of pancreatic duct (may produce multiple discrete strictures) • Additional extrabiliary manifestations of IRSD: Lymphadenopathy, sclerosing mesenteritis, retroperitoneal fibrosis, renal involvement

General Features

MR Findings

• Best diagnostic clue ○ Bile duct wall thickening and strictures in setting of autoimmune pancreatitis • Location ○ ISC classified based upon stricture location – Type 1: Distal (intrapancreatic) common bile duct (CBD) □ Most common type: May mimic pancreatic adenocarcinoma or cholangiocarcinoma – Type 2: Strictures distributed throughout intra- and extrahepatic ducts □ May mimic primary sclerosing cholangitis – Type 3: Strictures of duct bifurcation and distal duct □ May mimic cholangiocarcinoma – Type 4: Isolated hilar stricture □ May mimic cholangiocarcinoma • Size ○ Variable: Focal or diffuse involvement of biliary tree • Morphology ○ Concentric bile duct wall thickening and hyperenhancement ○ Typically long smooth stricture with upstream biliary ductal dilatation

• MRCP images nicely demonstrate irregularity and strictures of intrahepatic or extrahepatic bile ducts ○ Affected segments demonstrate concentric ductal wall thickening with hyperenhancement on T1WI C+ ○ Ductal dilatation upstream from sites of narrowing or stricture ○ Sites of stricture tend to be long and smooth (without wall irregularity) • Diffuse gallbladder wall thickening • Findings of concomitant autoimmune pancreatitis ○ Enlarged pancreas with abnormal signal (hypointense on T1WI and hyperintense on T2WI) ○ Rim of peripheral hypoenhancement and low T2WI signal with delayed enhancement ○ Multiple discontiguous pancreatic duct strictures on MRCP, which may resolve after administration of secretin

Radiographic Findings • ERCP ○ Distal CBD stricture and irregularity of main pancreatic duct (due to concomitant AIP) most frequent findings ○ Strictures of intra- and extrahepatic ducts rarely occur without pancreatic duct involvement ○ Long, smooth strictures (particularly of distal CBD) without irregularity

CT Findings • Circumferential focal or diffuse bile duct wall thickening ○ Most commonly affects distal CBD, but can affect any portion of biliary tree ○ Hyperenhancement of affected bile duct: Enhancement may persist during delayed phase ○ No vascular invasion, metastatic disease, or other secondary findings of malignancy

Biliary System

TERMINOLOGY

Ultrasonographic Findings • Intrahepatic biliary ductal dilatation • Bile duct wall thickening: No specific sonographic features to differentiate autoimmune cholangitis from other forms of cholangitis • Gallbladder wall thickening • Focal or diffuse enlargement/hypoechogenicity of pancreas (concomitant autoimmune pancreatitis)

Imaging Recommendations • Best imaging tool ○ MRCP, ERCP

DIFFERENTIAL DIAGNOSIS Primary Sclerosing Cholangitis • Irregular strictures affecting both intra- and extrahepatic bile ducts with alternating sites of dilatation, stricture, and normal-appearing ducts ○ Classically produces "beaded" strictures with "pruning" of the biliary tree in the more chronic setting • Usually seen in younger patients with a more indolent course than ISC • Unlike PSC, ISC more commonly affects distal CBD and tends to demonstrate longer segment strictures 931

Biliary System

Autoimmune (IgG4) Cholangitis

• Associated with inflammatory bowel disease (uncommon in ISC)

Ascending Cholangitis • Usually results from biliary obstruction (most often due to choledocholithiasis) • Thickening and hyperenhancement of bile ducts with upstream biliary dilatation and heterogeneous liver parenchymal enhancement

Benign Biliary Stricture • Benign stricture of CBD due to prior biliary catheterization or passed stone • No mural thickening, hyperenhancement, or imaging features of autoimmune cholangitis

Cholangiocarcinoma • Focal irregular mural thickening or intraductal papillary mass ○ Involved sites may demonstrate delayed contrast enhancement due to fibrous stroma of tumor • Other signs of malignancy often present, including vascular encasement, lymphadenopathy, and metastases

AIDS Cholangiopathy • Opportunistic infections affecting biliary tree in AIDS patients with very low CD4 counts (usually < 100) • Papillary stenosis frequent, with tapered narrowing of distal CBD and upstream biliary dilatation • Long segment extrahepatic duct strictures and gallbladder wall thickening may be present, while involvement of intrahepatic biliary tree can closely mimic PSC

Presentation • Most common signs/symptoms ○ Jaundice ○ alkaline phosphatase ○ serum IgG4 level – Very small subset of PSC patients (< 10%) may also have elevated IgG4 levels ○ Signs/symptoms of associated autoimmune pancreatitis: Epigastric pain, amylase/lipase • Other signs/symptoms ○ Signs/symptoms related to involvement of other organs in setting of IRSD ○ 40% of patients have history of allergy or asthma • Clinical profile ○ Diagnosis is made based on a combination of imaging, histopathology, elevated IgG4, and clinical response to steroids/azathioprine

Demographics • Age ○ Middle-age and elderly (most often 5th and 6th decades) • Gender ○ M > F (up to 8:1)

Natural History & Prognosis • May improve spontaneously, progress, or relapse, although relapse rate after therapy may be high (> 50%) • No known association with cholangiocarcinoma or pancreatic cancer

Pancreatic Adenocarcinoma

Treatment

• Presence of distal CBD stricture and narrowing/irregularity of pancreatic duct due to autoimmune pancreatitis in ISC may raise concern for pancreatic adenocarcinoma • No discrete mass present in most cases of ISC, but focal autoimmune pancreatitis may be very difficult to distinguish from malignancy

• Steroids most often induce long-term remission, although relapse may occur, particularly if there is extensive biliary and extrabiliary involvement ○ Other immunomodulator drugs (i.e., azathioprine) utilized for refractory or recurrent disease ○ If therapy effective, clinical and cholangiographic improvement seen within 6 weeks of treatment • Biliary stenting of extrahepatic strictures

PATHOLOGY General Features • Etiology ○ Exact pathophysiology not well understood ○ Some evidence for both autoimmune and allergic mechanisms • Associated abnormalities ○ Frequently associated with autoimmune pancreatitis ○ Involvement of other organs in setting of IRSD

Staging, Grading, & Classification • Other sites of involvement in IRSD ○ Most common: Autoimmune pancreatitis, autoimmune sclerosing cholangitis, sialadenitis (Mikulicz disease), nephritis, lymphadenopathy ○ Less common: Cholecystitis, orbital pseudotumor, dacryoadenitis, retroperitoneal fibrosis, Riedel thyroiditis, interstitial pneumonitis, sclerosing mesenteritis, vasculitis, hypophysitis • 60-90% have multiple organ involvement (2/3 had involvement of 3 organs in one study) 932

CLINICAL ISSUES

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Imaging features of ISC and PSC may overlap, although demographics and course of disease are different for each ○ PSC seen in younger patients with more indolent course ○ ISC has more acute presentation, is seen in older patients, responds to steroids, and may be associated with extrabiliary manifestations of IRSD ○ Some authors suggest that ISC and PSC are not completely separate conditions and indeed may be variations of same disease spectrum

SELECTED REFERENCES 1.

Joshi D et al: Review article: biliary and hepatic involvement in IgG4-related disease. Aliment Pharmacol Ther. ePub, 2014

Autoimmune (IgG4) Cholangitis Biliary System

(Left) CECT of an elderly man with jaundice shows thickening of the proximal right and left hepatic ducts and mild intrahepatic biliary ductal dilatation. (Right) Cholangiogram of the same patient shows strictures of the proximal right and left hepatic ducts. The patient's serum IgG4 was not elevated, but the strictures improved with empiric steroid therapy. An elevated IgG4 is a highly sensitive and specific marker for ISC, though IgG4 levels may vary widely during the disease course.

(Left) Axial CECT of a middleaged woman with jaundice and abdominal pain shows a diffusely enlarged pancreatic body/tail and mild thickening of the common duct post stent placement. (Right) ERCP of the same patient shows a hilar stricture . The patient had an elevated IgG4, and these imaging findings were found to represent AIP and ISC. The patient also had Riedel thyroiditis, a finding indicating a systemic fibrosclerosing process. The stricture and AIP improved after steroid therapy.

(Left) MRCP of an elderly man with jaundice shows a proximal common duct-hilar stricture and mild intrahepatic biliary dilatation. The location of the stricture strongly suggested cholangiocarcinoma, but an elevated serum IgG4 and positive IgG4 staining at cytology indicated ISC. (Right) ERCP of the same patient shows a complex stricture extending into the proximal right and left hepatic ducts. A preoperative diagnosis of ISC may be difficult if imaging findings of AIP are absent.

933

Biliary System

Primary Sclerosing Cholangitis KEY FACTS

TERMINOLOGY • Immune-mediated disease causing progressive inflammation, fibrosis, and stricturing of intrahepatic and extrahepatic ducts

IMAGING

PATHOLOGY

• Multifocal "beaded" strictures of intra- and extrahepatic ducts with intervening sites of dilated and normal ducts ○ Pruned appearance of biliary tree develops over time • CT/MR ○ Thickening and hyperenhancement of bile duct wall suggests active inflammation ○ Chronic involvement results in atrophy of peripheral liver, massive hypertrophy of central liver/caudate (pseudotumor of caudate), and lobulated, rounded liver contour – Frequent periductal and perivascular fibrosis, as well as confluent fibrosis in central liver: Low density on CT and T2 hyperintense on MR

• Idiopathic inflammatory process with likely autoimmune etiology affecting small, medium, and large-sized bile ducts • High association with other autoimmune disorders and inflammatory bowel disease (especially ulcerative colitis) • Increased risk of cholangiocarcinoma and other malignancies (including gallbladder cancer)

(Left) MRCP of a patient with primary sclerosing cholangitis (PSC) shows innumerable intrahepatic strictures. The extrahepatic bile duct is not significantly involved in this case, although the majority of PSC cases involve both the intrahepatic and extrahepatic ducts. (Right) Catheter cholangiogram shows multifocal strictures and moderate dilatation of the right intrahepatic bile ducts. Note the tight stricture of the main left hepatic duct with partial opacification of a very dilated left intrahepatic bile duct.

(Left) Percutaneous transhepatic cholangiography in a patient with a history of liver transplant for end-stage PSC-induced liver disease shows markedly irregular bile ducts with multifocal strictures and intraductal filling defects, compatible with recurrent PSC. (Right) Axial CECT in a patient with PSC demonstrates a cirrhotic, lobulated liver and ductal dilatation. The right hepatic duct is dilated, thickened, and hyperenhancing, suggesting active ductal inflammation.

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– Periphery of liver may show patchy T2 hyperintensity on MR due to edema/inflammation ○ Hepatolithiasis, cholelithiasis, and choledocholithiasis are common and appear as signal voids on MR

CLINICAL ISSUES • Most commonly seen in young (30-40 years) males, with incidence in Europe and North America • Usually worsens progressively with little proven benefit to various medical, endoscopic, or surgical interventions • Liver transplantation is curative, although primary sclerosing cholangitis (PSC) may recur in liver allograft

Primary Sclerosing Cholangitis

Abbreviations • Primary sclerosing cholangitis (PSC)

○ Confluent fibrosis (wedge-shaped site of parenchymal volume loss with capsular retraction) may be seen in chronic setting: Low T1WI signal, high T2WI signal, delayed enhancement

Definitions

CT Findings

• Chronic, immune-mediated disease causing progressive inflammation, fibrosis, and stricturing of the intrahepatic and extrahepatic ducts

• Dilation of intrahepatic and extrahepatic ducts ○ "Beaded" morphology may be difficult to appreciate on CT, but multiplanar reformations often helpful ○ Abnormal ductal arborization pattern: Cannot follow branching ducts on sequential images ○ Abnormal thickening and hyperenhancement of bile duct walls suggests active inflammation ○ Intrahepatic biliary calculi are common • End-stage PSC: Markedly dysmorphic, cirrhotic liver with progressive hypertrophy of caudate lobe/deep right lobe and atrophy of peripheral liver with abnormally rounded, lobulated liver contour ○ Periphery of liver often appears hypodense due to fibrosis and hepatocellular necrosis resulting from poor biliary drainage of liver periphery ○ Central liver often relatively higher attenuation compared to peripheral liver due to preserved drainage by patent short bile ducts – More evident on NECT than CECT ○ Frequent low-attenuation periductal and perivascular fibrosis, as well as confluent fibrosis in central liver (with wedge-shaped hypodensity and capsular retraction) • Inclusion of delayed phase images very helpful to evaluate for presence of cholangiocarcinoma ○ Suggest cholangiocarcinoma in setting of discrete mass with delayed enhancement, progressive segmental/lobar dilation of ducts or nodular bile duct wall thickening • Lymphadenopathy in right upper quadrant and retroperitoneum common

IMAGING General Features • Location ○ Common bile duct (CBD) involved in > 90% of patients ○ Involvement of both intra- and extrahepatic ducts in 87% – Isolated involvement of intrahepatic (11%) or extrahepatic (2%) ducts is unusual ○ Most severely affected segments of biliary tree are usually main right and left bile ducts ○ Strictures can affect cystic duct and pancreatic duct • Morphology ○ In patients with PSC-induced end-stage cirrhosis, liver is markedly deformed (to much greater extent than with other common causes of cirrhosis) – Contour is grossly lobulated and rounded with peripheral atrophy and central hypertrophy – Enlargement of central liver and caudate with peripheral atrophy described as "pseudotumoral" enlargement of caudate – Atrophy/hypertrophy complex may even occur in absence of cirrhosis

MR Findings • MRCP is best noninvasive imaging technique for evaluating changes in biliary tree • MRCP demonstrates multifocal "beaded" strictures of intrahepatic and extrahepatic ducts ○ Alternating sites of irregular strictures, mildly dilated ducts, and normal-caliber ducts ○ Visualization of greater than expected number of peripheral ducts on MRCP is clue to presence of peripheral intrahepatic ductal strictures ○ Pruned appearance of biliary tree develops as disease progresses, with obliteration of small peripheral ducts ○ Hepatolithiasis, cholelithiasis, and choledocholithiasis are common (usually pigmented stones) and appear as signal voids on all pulse sequences • T1W C+ images (particularly on arterial phase images) demonstrates heterogeneous, patchy hyperenhancement often in periductal distribution • Thickening and hyperenhancement of bile ducts on T1WI C+ suggests acute inflammation • Chronic involvement results in atrophy of peripheral liver, hypertrophy of central liver, and lobulated, rounded liver contour ○ Liver periphery often shows patchy T2 hyperintensity due to parenchymal edema/inflammation ○ Periportal and periductal T2 hyperintensity also common

Biliary System

TERMINOLOGY

Radiographic Findings • Cholangiography (ERCP or PTC) ○ Multifocal short segment biliary strictures involving both intrahepatic and extrahepatic ducts with intervening sites of normal or mildly dilated ducts – ± diverticula adjacent to strictures – Mural irregularity of ducts common (50%), ranging from a fine, brush-border appearance to coarse, shaggy, or frankly nodular appearance □ nodularity raises concern for cholangiocarcinoma – "Pruned-tree" appearance can develop over time: Opacification of central ducts with obliteration of small peripheral ducts ○ Strictures can vary from 1-2 mm to several cm – Dominant stricture: Marked dilation of duct upstream from tight, long stricture (defined as < 1.5 mm in CBD or < 1 mm in left or right main duct) □ Dominant stricture should raise concern for cholangiocarcinoma, particularly if stricture and upstream dilatation progress over time ○ Intraluminal filling defects (5-10%) usually represent intraductal calculi particularly when small (2-5 mm) – Large and noncalcified (> 1 cm) filling defects should raise concern for cholangiocarcinoma 935

Biliary System

Primary Sclerosing Cholangitis

Ultrasonographic Findings • Bile ducts demonstrate wall thickening at sites of stenosis with intervening segmental dilation ± biliary stones • Involvement of gallbladder wall (15%) due to PSC-related inflammation results in asymmetric or symmetric wall thickening

Imaging Recommendations • Best imaging tool ○ MRCP or cholangiography (in cases with equivocal MRCP or for treatment of complications)

DIFFERENTIAL DIAGNOSIS Ascending Cholangitis • Acute pyogenic infection due to biliary obstruction • Thickening and hyperenhancement of bile duct wall with adjacent fat stranding ± debris within duct lumen • Heterogeneous liver enhancement (particularly in arterial phase) can be diffuse, geographic, patchy, or periductal

AIDS Cholangiopathy • Biliary inflammation caused by AIDS-related opportunistic infections • Multiple intrahepatic strictures with papillary stenosis and gallbladder wall thickening • Changes in intrahepatic ducts may be identical to PSC

Autoimmune (IgG4) Cholangitis • IgG4-related lymphoplasmacytic infiltration of biliary tree frequently associated with autoimmune pancreatitis • Imaging findings overlap with PSC, but usually seen in older population with more acute onset

Chemotherapy-Induced Cholangitis • Iatrogenic cholangitis caused by intraarterial chemotherapy • May be indistinguishable from PSC, but peripheral bile ducts usually less involved than in PSC, while central bile ducts more commonly involved

PATHOLOGY General Features • Etiology ○ Idiopathic inflammatory process with likely autoimmune etiology affecting small, medium, and large-sized ducts – Bile duct injury mediated by immune cells (T cells, natural killer cells, B cells, macrophages) – Frequent association with autoantibodies (ANCA, ANA, ASMA) ○ Theorized that bacteria from inflamed colonic mucosa may trigger initial insult in PSC ○ Likely genetic contribution to etiology, with siblings of PSC patients having 100x greater risk of developing PSC – Several genetic associations, including HLA class I, HLA class II, and major histocompatibility complex on chromosome 6 • Associated abnormalities ○ Ulcerative colitis (up to 90%), Crohn disease (13%) ○ Other autoimmune processes (thyroiditis, retroperitoneal fibrosis) ○ risk of cholangiocarcinoma (overall lifetime risk of 1015%; annual risk of 1.5%) 936

– Suspect malignancy with rapid clinical deterioration, worsening liver function tests, and elevated CA 19-9 ○ PSC patients are at risk for developing several other malignancies, including gallbladder carcinoma, hepatocellular carcinoma, and colorectal cancer

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Up to ~ 40% of patients may be asymptomatic at presentation (often discovered incidentally) ○ Fatigue, pruritus, RUQ pain, hepatosplenomegaly, weight loss, and jaundice ○ bilirubin, alkaline phosphatase

Demographics • Age ○ Median age of onset: 30-40 years • Gender ○ M: F (2:1) • Epidemiology ○ Incidence varies geographically, with higher incidence in northern European and North American populations – Prevalence up to 16.2 per 100,000 inhabitants

Natural History & Prognosis • Variable natural history, but usually worsens progressively • Involvement of small intrahepatic bile ducts (so-called "small duct" PSC) may be only or earliest manifestation of PSC ○ Classic obliterative fibrosis of medium- and large-sized ducts (so-called "large-duct" PSC) occurs at later stage, resulting in cholestasis with progression to secondary biliary cirrhosis and hepatic failure ○ Multicentric nature and chronic obstruction of bile ducts leads to cirrhosis in many patients • Complications: Biliary cirrhosis, portal hypertension, cholangiocarcinoma, gallbladder carcinoma • Prognosis: 5-year survival 88%; median survival 10-12 years from time of diagnosis ○ > 50% of patients require liver transplant within 10-15 years of symptom onset

Treatment • Little proven benefit to various medical, endoscopic, or surgical interventions • Treatment of dominant strictures with balloon dilatation ± stent placement ○ Dominant strictures may require biliary bypass or resection of extrahepatic stricture with Roux-en-Y hepaticojejunostomy • Liver transplantation is curative, although PSC may recur in liver allograft

SELECTED REFERENCES 1.

Costello JR et al: MR Imaging of Benign and Malignant Biliary Conditions. Magn Reson Imaging Clin N Am. 22(3):467-488, 2014

Primary Sclerosing Cholangitis Biliary System

(Left) MRCP MIP reconstruction shows irregular "beaded" strictures of the intrahepatic ducts, consistent with the patient's PSC. There is a dominant stricture of the left hepatic duct beginning at the level of the confluence. (Right) Axial T1WI FS C+ MR in the same patient demonstrates a subtle hypoenhancing mass encasing the proximal aspect of the left hepatic duct, explaining the dominant stricture on the MRCP image. This represents a cholangiocarcinoma, for which PSC is a major risk factor.

(Left) Axial CECT in a patient with longstanding PSC demonstrates a nodular cirrhotic liver. Note the massive hypertrophy of the caudate , with atrophy of the peripheral right hepatic lobe . (Right) T2WI FS MR shows characteristic morphologic changes of advanced PSC. Note the enlargement of the central liver and scattered irregular biliary ductal dilatation . Subtle peripheral T2 hyperintensity is due to peripheral atrophy and fibrosis.

(Left) Axial NECT shows massive hypertrophy and increased density of the caudate in a patient with longstanding PSC compared with the atrophic, hypodense, peripheral portions of the liver. Because this is often misinterpreted as a caudate tumor, this finding is sometimes called "caudate pseudotumor." (Right) Longitudinal ultrasound shows the thickened, hyperechoic wall of the common duct in a patient with PSC.

937

Biliary System

Biloma KEY FACTS

TERMINOLOGY

• ERCP: Can delineate site of leakage and guide treatment

• Loculated collection of bile within abdomen resulting from bile leak

PATHOLOGY

IMAGING • CT:Water-attenuation fluid collection within or adjacent to liver with exertion of mass effect on adjacent structures ○ Usually simple in appearance, but may rarely have internal debris, blood products, etc. ○ No identifiable capsule/peripheral enhancement • MR: Usually well-defined fluid collection, which is T2WI hyperintense and T1WI hypointense ○ Hepatobiliary contrast agents (e.g., Eovist) are excreted into biliary tree and may identify site of bile leak in hepatobiliary phase ○ Standard MRCP cannot definitively identify site of bile leak or differentiate biloma from other fluid collections • Hepatobiliary scintigraphy: Focal accumulation of radiotracer outside biliary tree and bowel

(Left) Axial CECT in a patient who had recently undergone partial hepatectomy demonstrates development of a biloma in the surgical bed. (Right) Frontal ERCP image in the same patient demonstrates active extravasation of contrast into the biloma from the right hepatic lobe bile duct distribution. Unlike other imaging modalities, ERCP can definitively identify an active bile leak and confirm that a fluid collection represents a biloma.

(Left) Axial CECT in a patient with fever and abdominal pain 21 days after a laparoscopic posterior segment wedge resection of a small hyalinized hemangioma shows a central right lobe biloma and surrounding devascularized, infarcted liver . (Right) ERCP of the same patient shows a bile leak with spillage of contrast into the biloma, and an appropriately positioned drain . The biloma completely resolved after percutaneous drainage and biliary stent placement.

938

• Most commonly the result of iatrogenic injury to biliary tract ○ Cholecystectomy (especially laparoscopic), radiofrequency ablation of focal hepatic lesions, percutaneous liver biopsy, liver transplantation • Traumatic bile leaks due to blunt or penetrating trauma can occur but are relatively uncommon

CLINICAL ISSUES • ERCP with sphincterotomy and plastic stent placement (to decrease biliary pressure and control leak) is effective in majority (> 90%) of cases • Percutaneous drainage of collection (often under image guidance) if biloma is large, infected, or increasing in size • Biloma associated with transection of extrahepatic duct may require hepaticojejunostomy

Biloma

Hepatic Hematoma

Definitions

• Unencapsulated collection with attenuation higher than biloma (unclotted blood: 30-45 HU, clotted blood: > 60 HU )

• Loculated collection of bile within abdomen resulting from bile leak

Hepatic Abscess

IMAGING General Features • Best diagnostic clue ○ Loculated fluid collection of simple fluid attenuation in close proximity to liver or biliary tree • Location ○ Either intrahepatic or extrahepatic – Most commonly perihepatic (gallbladder fossa, Morison pouch) and subphrenic

Radiographic Findings • ERCP can delineate site of leakage and presence of aberrant ducts that might change treatment approach

CT Findings • Water-attenuation fluid collection within or adjacent to liver with exertion of mass effect on adjacent structures ○ Usually simple in appearance, but may rarely have internal debris, blood products, etc. ○ Usually no identifiable capsule or peripheral enhancement

MR Findings • Typically well-defined fluid collections, which are T2WI hyperintense and T1WI hypointense ○ No internal/peripheral enhancement or capsule • MRCP delineates relationship of biloma with adjacent biliary tree and anomalies in bile duct anatomy ○ Cannot definitively identify site of bile leak or differentiate biloma from other fluid collections • Hepatobiliary contrast agents (e.g., Eovist) are excreted into biliary tree and may identify site of bile leak ○ Active extravasation visualized in hepatobiliary phase – Delayed images helpful in patients with biliary dilatation or impaired hepatic function to increase sensitivity ○ High reported sensitivities for bile leaks (~ 100%)

Ultrasonographic Findings • Usually simple intrahepatic/perihepatic fluid collection • May have low-level echoes due to hemorrhage/infection

Nuclear Medicine Findings • Hepatobiliary scintigraphy ○ Focal accumulation of radiotracer outside biliary tree/bowel ○ Delayed (24 hour) images to visualize slow leaks

DIFFERENTIAL DIAGNOSIS Simple Hepatic Cyst • Simple-appearing intrahepatic cyst with water attenuation < 15 HU • No history of risk factors for biloma, such as surgery/trauma

Biliary System

TERMINOLOGY

• Pyogenic: Multilocular, rim-enhancing fluid collection with thick wall and surrounding parenchymal low-density edema

Postoperative Fluid Collections (Seroma, Lymphocele, Hematoma, Abscess) • May appear identical to biloma when adjacent to liver or biliary tree

PATHOLOGY General Features • Etiology ○ Most commonly the result of iatrogenic injury – Cystic duct leak or common bile duct injury after cholecystectomy (most common) – Post radiofrequency ablation of focal hepatic lesions – Post perforation of bile duct following PTC, ERCP, sphincterotomy, or tube change – Post percutaneous liver biopsy – Post liver transplantation ○ Traumatic bile leaks can occur either due to blunt or penetrating trauma, but are relatively uncommon

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Vague abdominal pain, persistent nausea, and vomiting ○ Fever and leukocytosis if biloma is infected ○ High aspirated fluid/serum bilirubin ratio

Demographics • Epidemiology ○ 0.8-1.1% incidence of significant bile leak after laparoscopic cholecystectomy ○ 2-25% incidence of bile leaks reported after liver transplant or hepatic resection

Natural History & Prognosis • May be asymptomatic: Most bilomas gradually decrease in size spontaneously over weeks • If symptomatic, usually present in 1st postoperative week

Treatment • ERCP with sphincterotomy and plastic stent placement to decrease biliary pressure and control leak is effective in majority (> 90%) of cases ○ Percutaneous drainage of collection (often under image guidance) if biloma is large, infected, or increasing in size • Biloma associated with complete transection of extrahepatic duct may require hepaticojejunostomy

SELECTED REFERENCES 1.

Melamud K et al: Biliary imaging: multimodality approach to imaging of biliary injuries and their complications. Radiographics. 34(3):613-23, 2014

939

Biliary System

Biloma

(Left) Axial CECT in a patient who had just undergone a Whipple procedure demonstrates a collection of gas and fluid immediately adjacent to the hepaticojejunostomy. Given the proximity of the biliary anastomosis, a biloma was strongly suspected. (Right) Coronal CECT in the same patient demonstrates placement of a percutaneous drain into the collection , as there was concern for superinfection. The collection was found to have markedly elevated bilirubin levels, in keeping with a biloma.

(Left) Axial CECT in a liver transplant patient with known hepatic artery thrombosis shows an intrahepatic collection with a branching configuration that parallels the bile ducts, representing a biloma due to arterial thrombosis. (Right) Fluoroscopic image in the same patient demonstrates a catheter placed into the biloma. Injection of contrast opacifies both the biloma and nondilated ducts , confirming communication between necrotic bile ducts and the biloma.

(Left) Axial CECT image obtained in a patient who presented with blunt abdominal trauma demonstrates a hepatic fracture traversing the liver in the plane of the main lobar fissure. (Right) Follow-up axial CECT performed 2 weeks later in the same patient, now presenting with RUQ pain, shows a large biloma at the site of the previous hepatic fracture. Post-traumatic bilomas occur because of disrupted intrahepatic bile ducts and bile leakage into lacerations/hematomas.

940

Biloma Biliary System

(Left) Anterior dynamic views from a Tc-99m hepatobiliary study after liver transplant show tracer activity in the lateral perihepatic space and none within the small bowel, compatible with a bile leak. (Right) T1WI FS MR of a young woman obtained 1 hour after mangafodipir trisodium administration shows accumulated, extravasated, contrast-enhanced bile within the gallbladder fossa post cholecystectomy. MR hepatobiliary agents may be particularly useful for delineating biliary injuries and bilomas.

(Left) Axial CECT of a patient with abdominal pain and fever a few weeks left lobe resection shows a gascontaining elliptical fluid collection along the surgical margin of the liver. (Right) ERCP of the same patient confirms a bile leak/biloma . Asymptomatic post-traumatic/operative bilomas often resolve without intervention. Biloma growth, pain, and leukocytosis should, however, prompt treatment. This biloma was successfully treated by percutaneous drainage and antibiotics.

(Left) CECT of a patient with elevated liver function tests 2 years post liver transplantation shows a posterior segment biloma . A CECT performed 1 month prior showed a thrombosed hepatic artery and small hepatic arterial collaterals. (Right) Ultrasound of the same patient shows a hepatic dome biloma . Liver transplant bilomas are typically due to hepatic arterial stenoses/thromboses. Biliary ischemia leads to bile duct necrosis, sloughing, and intrahepatic bilomas.

941

Biliary System

Ischemic Bile Duct Injury KEY FACTS

• Nonanastomotic biliary strictures in liver allograft originally described in setting of hepatic artery thrombosis/stenosis, but now known to occur due to a variety of other microangiopathic and immunological injuries

○ Bile duct casts appear as intraductal hyperdense material ○ CT not sensitive for early stage ischemic injury • MR: Linear high T1 signal intensity may be visualized within dilated central ducts, characteristic of biliary cast

IMAGING

PATHOLOGY

• Predominant involvement of middle 1/3 of common bile duct and hepatic duct confluence ○ Solitary or multifocal strictures of variable length • Cholangiography: Gold standard for diagnosis ○ Appearance may be identical to PSC with "beading" of biliary tree (alternating stenosis, normal ducts, and mild dilatation) ○ Biliary casts appear as filling defects within duct lumen • CT: Scattered irregular biliary dilatation with bile duct wall thickening and hyperenhancement ○ Presence of intrahepatic biloma or liver infarct should prompt careful assessment for HAT/HAS

• Classically due to hepatic artery thrombosis, but possible without arterial compromise (ischemic-type biliary lesions) • Also associated with prolonged warm and cold ischemic time, ABO incompatibility, and chronic rejection

TERMINOLOGY

(Left) Coronal CECT MIP reconstruction in a liver transplant patient demonstrates abrupt occlusion of the hepatic artery near its origin from the celiac artery. (Right) Cholangiogram in the same patient demonstrates features of ischemic cholangiopathy due to hepatic artery occlusion, including a dominant stricture in the common duct and irregularity of the intrahepatic ducts.

(Left) ERCP of a patient with jaundice after liver transplant shows a filling defect in the hilum, representing a hilar biliary cast , and diffusely irregular intrahepatic ducts. The patient's course was complicated by portal vein thrombosis and rejection, but the hepatic artery was patent on US. (Right) T1WI FS MR of the same patient shows a typically high signal cast at the duct bifurcation. Multiple ischemic and immunological insults may result in the strictures and casts that are characteristic of ischemic cholangiopathy.

942

CLINICAL ISSUES • Initial treatment: Endoscopic or percutaneous dilatation/stenting of strictures and clearing of biliary casts • Roux-en-Y hepaticojejunostomy for extrahepatic strictures unresponsive to dilatation/stenting • Retransplantation may be necessary in patients with secondary biliary cirrhosis, recurrent cholangitis, or progressive cholestasis

Ischemic Bile Duct Injury

Synonyms

•

• Ischemic cholangitis, ischemic cholangiopathy

Definitions • Nonanastomotic biliary strictures in liver allograft originally described in setting of hepatic artery thrombosis (HAT) or stenosis (HAS), but now known to occur due to a wide variety of other microangiopathic and immunological injuries

• •

IMAGING

○ Most often utilized to evaluate for strictures at hepaticojejunostomy T2WI, MRCP, and T1WI C+ Eovist cholangiographic images demonstrate luminal irregularity, stenosis, and scattered biliary ductal dilatation May be associated with T2-hyperintense intrahepatic bilomas or liver infarcts Linear high T1 signal intensity may be visualized within dilated central ducts, characteristic of biliary cast ○ Extremely uncommon in absence of ischemic cholangiopathy and virtually diagnostic ○ MR allows distinction between cast (T1 hyperintense) and stones (hypointense on all pulse sequences) MRA can show hepatic artery thrombosis or stenosis

General Features

•

• Best diagnostic clue ○ Nonanastomotic biliary strictures in liver allograft • Location ○ Can involve intrahepatic &/or extrahepatic ducts ○ Predominant involvement of middle 1/3 of common bile duct and hepatic duct confluence > intrahepatic ducts • Morphology ○ Can be solitary or multifocal strictures ○ Variable length: Short or long segment

Ultrasonographic Findings

Radiographic Findings • Cholangiography (ERCP or PTC) is gold standard for diagnosis of ischemic cholangitis ○ Cholangiographic appearance may be nearly identical to primary sclerosing cholangitis ○ Luminal irregularity of bile ducts with beaded appearance (alternating sites of stenosis, normal ducts, and mild dilatation) – Strictures evolve over time, beginning as sites of irregularity and developing into fibrotic strictures – Rare diffuse duct necrosis and biliary sloughing ○ Biliary casts appear as filling defects within duct lumen ○ May demonstrate communication of bile ducts with intrahepatic bilomas

CT Findings • Scattered irregular biliary dilatation with bile duct wall thickening and hyperenhancement ○ Presence of intrahepatic biloma or liver infarct in posttransplant setting should prompt careful assessment of hepatic artery for HAT/HAS ○ Bile duct casts, highly suggestive of ischemic cholangiopathy, appear as linear hyperdense material within bile duct – May not be readily distinguishable from stone on CT (both may appear hyperdense) • CT not sensitive for early stage ischemic-type biliary lesions (ITBL) ○ Transplanted liver may not develop biliary dilatation despite severe ductal stenosis ○ If high clinical suspicion for ITBL, proceed to cholangiography (ERCP, PTC, or MRCP) • CTA can show hepatic artery narrowing or thrombosis

MR Findings

Biliary System

TERMINOLOGY

• Grayscale ultrasound ○ Poor sensitivity for early stage ischemic-type biliary injury ○ May show intrahepatic ductal dilatation and thickening ○ Biliary casts appear as echogenic material within dilated bile ducts ○ Advanced biliary ischemia due to HAT or HAS may result in presence of intrahepatic fluid collections (bilomas) ○ Extrahepatic biliary dilatation is nonspecific finding in post-transplant liver and does not necessarily imply ischemic cholangiopathy – Nonobstructive dilatation of extrahepatic ducts (without intrahepatic biliary dilatation) may be due to papillary dyskinesia or discrepancy between size of donor and recipient ducts • Pulsed Doppler ○ Evaluate for evidence of HAT or HAS – Hepatic artery stenosis (or chronic HAT with collaterals) □ Turbulent flow within hepatic artery with focal aliasing at site of stenosis □ Usually occurs at or near anastomosis and affects 11% of patients (mean 3 months after surgery) □ Tardus parvus waveform (systolic acceleration time > 100 msec): Rounded spectral Doppler waveforms with delayed systolic upstrokes □ Intrahepatic arterial resistive index < 0.5 □ Peak anastomotic systolic velocity > 200 cm/sec □ Post-anastomotic hepatic arterial peak systolic velocity < 48 cm/sec (may increase specificity) – Hepatic artery thrombosis: Failure to visualize hepatic artery on US □ CTA or MRA required for confirmation, as poor acoustic windows, arterial spasm, low cardiac output, or severe parenchymal edema can simulate thrombosis on US □ Usually occurs weeks to months after surgery

Imaging Recommendations • Best imaging tool ○ Cholangiography (PTC, ERCP): Gold standard for diagnosis and allows intervention ○ MRCP best noninvasive test for changes in biliary tree ○ US followed by CTA/MRA for assessment of HAS/HAT

• Strong correlation between MRCP and cholangiography • Hepatobiliary contrast agents (i.e., Eovist) can be used for cholangiographic images in hepatobiliary phase 943

Biliary System

Ischemic Bile Duct Injury

– Intrinsic susceptibility to reperfusion/reoxygenation injury ○ Hereditary hemorrhagic telangiectasia, radiation, polyarteritis nodosa, severe atherosclerosis, and vasculitis have known associations with ischemic cholangiopathy ○ Cholangiopathy after intraarterial chemotherapy, hepatic artery chemoembolization, and AIDS cholangiopathy may also result partially from ischemia

DIFFERENTIAL DIAGNOSIS Anastomotic Biliary Ductal Stricture • Most often at choledocho-choledochal (orthotopic transplantation) or choledochojejunal anastomosis (living donor) • Not associated with additional strictures in biliary tree

Ascending Cholangitis • Pyogenic infection of biliary tree due to biliary obstruction • Biliary dilatation with duct wall thickening and heterogeneous parenchymal enhancement

Primary Sclerosing Cholangitis • May be virtually identical to ischemic cholangitis on cholangiography or MRCP • May recur years following liver transplantation, whereas ischemic cholangiopathy tends to develop in first few months after transplant

Choledocholithiasis • Alteration in bile composition after liver transplantation increases risk of developing biliary stones • Stones may be mistaken for biliary cast on CT or ERCP • Low signal on all MR pulse sequences

PATHOLOGY General Features • Etiology ○ Nonanastomotic biliary strictures initially described in setting of hepatic artery thrombosis and were thought to be a merely ischemic entity – Early thrombosis of hepatic artery disrupts blood supply before transcapsular collaterals have time to form, resulting in ischemic bile duct injury – However, can be seen in absence of arterial compromise, with ischemic cholangiopathy in absence of hepatic artery thrombosis or stenosis described as ischemic-type biliary lesions (ITBL) □ ITBL now believed to be multifactorial ○ Risk factors – Ischemic injury □ Prolonged warm ischemic time (during organ harvesting or implantation) □ Prolonged cold ischemic time □ Reperfusion injury □ Disturbed hepatic arterial blood flow (thrombosis, stenosis, increased resistance) – Immunological injuries □ ABO incompatibility □ Preexisting autoimmune disease (primary sclerosing cholangitis, autoimmune hepatitis, etc.) □ CMV infection □ Chronic rejection (direct injury to biliary epithelium + indirect injury due to arteriopathy) – Bile-salt-induced injury □ Alteration in bile composition and flow ○ Biliary epithelial cells are more prone to ischemic injury – Solely supplied by hepatic artery, with 50% of hepatic artery blood flow destined for bile ducts via peribiliary plexus (microvascular network supplying bile ducts) 944

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Nonspecific presentation, including abdominal discomfort, cholestasis, and fever ○ -glutamyl transferase, alkaline phosphatase

Demographics • Epidemiology ○ Usually occurs within first 6 months after transplantation ○ Incidence: 5-15% of liver allografts, but decreased compared to beginning of transplant era (~ 30%)

Natural History & Prognosis • Formation of biliary casts can result in "biliary cast syndrome," with casts preventing normal bile drainage and causing biliary obstruction/infection • Biliary complications after liver transplant associated with increased mortality rate ○ ~ 50% of patients will ultimately either die or require retransplantation

Treatment • Initial treatment: Endoscopic or percutaneous dilatation/stenting of strictures and clearing of biliary casts (reported success rate of 50%) ± PTC drainage • Ursodeoxycholic acid (Ursodiol): Theoretically improves bile composition and flow, but little supportive evidence • Roux-en-Y hepaticojejunostomy for extrahepatic strictures unresponsive to dilatation/stenting • Retransplantation may be necessary in patients with secondary biliary cirrhosis, recurrent cholangitis, or progressive cholestasis

DIAGNOSTIC CHECKLIST Consider • CT and US are not sensitive for evaluation of early stage ischemic bile duct injury ○ If persistent high clinical suspicion for ischemic bile duct injury, proceed to MRCP or cholangiography • Doppler US should be performed to assess hepatic arterial patency if ischemic cholangitis is suspected, with CTA or MRA for confirmation

SELECTED REFERENCES 1.

Luo Y et al: Graft cholangiopathy: etiology, diagnosis, and therapeutic strategies. Hepatobiliary Pancreat Dis Int. 13(1):10-7, 2014

Ischemic Bile Duct Injury Biliary System

(Left) Coronal MRCP MIP reconstruction in a patient with hepatic artery thrombosis demonstrates extensive irregularity throughout the biliary tree with apparent filling defects in the central bile ducts, compatible with ischemic cholangiopathy. A biliary drainage catheter is in place. (Right) Axial T1WI MR in the same patient demonstrates diffuse biliary dilatation with extensive T1 hyperintense biliary "cast" material distending the ducts. The biliary drainage catheter is again noted.

(Left) Cholangiogram in a liver transplant patient with a known history of hepatic artery thrombosis demonstrates a classic appearance of ischemic cholangiopathy, with multiple strictures of the intrahepatic and extrahepatic ducts. The appearance is indistinguishable from primary sclerosing cholangitis. (Right) Cholangiogram in a liver transplant patient with severe hepatic artery stenosis demonstrates extensive irregularity and stricturing of the biliary tree, compatible with ischemic cholangiopathy.

(Left) Axial CECT of a woman 4 years post liver transplant shows extensive biliary necrosis. The left bile duct is expanded and irregular, and the right duct is obscured by an adjacent biloma . The patient was retransplanted. (Right) MRCP of a patient post liver transplantation shows a dominant ischemic stricture and moderate intrahepatic ductal dilatation. The hepatic artery was patent on Doppler US. Brush biopsies of the stricture were negative, and a liver biopsy showed changes compatible with ischemic reperfusion injury.

945

Biliary System

Biliary Trauma KEY FACTS

IMAGING • Trauma: Most common site of injury is gallbladder (GB) followed by extrahepatic and intrahepatic ducts • Postoperative injuries: Common hepatic duct and hepatic hilum most common locations • GB injury ○ Pericholecystic free fluid, intraluminal or pericholecystic hematoma, or GB wall thickening ○ Poor definition of GB wall, abnormal GB contour, or collapsed GB, particularly with surrounding pericholecystic fluid, suggest GB perforation ○ Unusual positioning of GB or separation of GB from normal location in GB fossa suggests GB avulsion • Bile duct injuries ○ Can include tears, transections, or ligations, and may be associated with bile leaks ○ Free fluid or loculated collections (bilomas) in the right upper quadrant adjacent to biliary tree

(Left) Axial CECT shows hematoma separating the gallbladder from its normal location in the gallbladder fossa. The patient was taken to surgery where the gallbladder was found to be "avulsed" from its hepatic attachment and leaking bile. (Right) ERCP in a patient after cholecystectomy demonstrates a high-grade biliary stricture immediately adjacent to a surgical clip , in keeping with an iatrogenic stricture. The stricture in this case ultimately required hepaticojejunostomy.

(Left) Axial CECT in a patient after blunt trauma demonstrates a deep liver laceration and small hemoperitoneum. The depth of the laceration raised concern for biliary transection. The patient developed signs of bile peritonitis. (Right) ERCP in the same patient shows extravasation of contrast from a transected bile duct . The patient was successfully treated with biliary stenting without surgery. The biliary and hepatic injuries resolved.

946

○ Proximal biliary dilatation with abrupt narrowing of duct at site of bile duct laceration or stricture ○ MR hepatobiliary contrast agents (e.g., Eovist) can be utilized to directly visualize leak or stricture ○ Tc-99m hepatobiliary scintigraphy very sensitive for both bile leaks and biliary obstruction ○ Bile leaks may be identified as sites of active contrast extravasation on cholangiography

CLINICAL ISSUES • Trauma-related injuries to biliary tree are rare, accounting for only 0.1% of all trauma admissions • Iatrogenic injuries more common, with ~ 2,500 bile duct injuries during cholecystectomy in United States • Gallbladder injuries treated with cholecystectomy • Minor bile duct injuries treated conservatively with stent placement or drainage catheter • More severe injuries require surgical treatment (usually Roux-en-Y hepaticojejunostomy)

Biliary Trauma

General Features • Location ○ Trauma: Most common site of injury is gallbladder (GB) – Injuries to intrahepatic ducts usually occur with concomitant liver injury, while extrahepatic bile duct injuries most frequently involve common bile duct/hepatic duct ○ Postoperative injuries: Common hepatic duct (45-64%) and hepatic hilum (20-33%) most common locations – Most common injury is common duct transection (common duct mistaken for cystic duct during cholecystectomy) – Postoperative bile leaks usually arise from cystic duct stump, duct of Luschka (accessory duct in right hepatic lobe that traverses GB fossa), and GB bed

Radiographic Findings • ERCP ○ Can facilitate definitive diagnosis and treatment of bile leaks and simple strictures ○ Bile leaks may be identified as sites of active contrast extravasation – ERCP can define site of leak in 95% of cases ○ Post-traumatic strictures typically focal, smooth areas of narrowing with proximal dilation ○ Percutaneous transhepatic cholangiography (PTC) may be required in cases of severe extrahepatic duct stricture to fully evaluate intrahepatic biliary tree or more proximal extrahepatic duct

MR Findings • Hepatobiliary contrast agents (e.g., Eovist) can be utilized to directly visualize leak or stricture ○ Contrast is excreted into biliary tree in delayed hepatobiliary phase (15-30 minutes), creating MR cholangiogram ○ Active extravasation of contrast in cases of bile leaks/lacerations – Sensitivity for bile leaks may be as high as 95% ○ May allow better definition of strictures or bile duct narrowing compared to conventional MRCP • Conventional MRCP can define sites of stricture or narrowing in biliary tree but cannot accurately define exact site of bile leak

Biliary System

IMAGING

Ultrasonographic Findings • Proximal biliary dilation with gradual tapering of duct diameter and no surrounding mass present • Bilomas are usually anechoic, well-marginated fluid collections (some internal low-level echoes possible in setting of superinfection or associated hemorrhage) • Echogenic material in bile ducts or gallbladder should suggest hemobilia

Angiographic Findings • Hemobilia: Diagnosis most commonly confirmed by selective hepatic arteriography, demonstrating extravasation of contrast material into biliary tree ○ Depicts or excludes hepatic artery aneurysm/pseudoaneurysm (causes 10% of biliary bleeding cases)

CT Findings

Nuclear Medicine Findings

• Gallbladder injury ○ Imaging findings may vary depending on degree of injury, and some mild gallbladder contusions may be invisible on imaging ○ Presence of pericholecystic free fluid, intraluminal or pericholecystic high-density hematoma, or gallbladder wall thickening should raise concern for injury ○ Poor definition of gallbladder wall (i.e., sites of nonenhancement), abnormal GB contour, or collapsed GB, particularly with surrounding pericholecystic fluid, raises suspicion for GB perforation ○ Active extravasation may rarely be seen within GB lumen (most evident on arterial phase images) ○ Unusual positioning of GB or separation of GB from normal location in GB fossa in cases of avulsion ○ Suspect GB injury if liver laceration extends into GB fossa • Bile duct injuries ○ Free fluid or loculated collections (bilomas) in right upper quadrant (either intra- or extrahepatic) adjacent to biliary tree – CT cannot differentiate bilomas from other common post-traumatic and postsurgical fluid collections (hematomas, seromas, lymphocele, abscess) – CT cannot accurately define site of leak (although location of biloma may be suggestive) ○ Proximal biliary dilatation with abrupt narrowing of duct at site of bile duct laceration or stricture ○ Biliary-enteric fistula: Oral contrast visible in both bowel and biliary tree

• Tc-99m hepatobiliary scintigraphy is very sensitive for both bile leaks and biliary obstruction ○ Accumulation of radiotracer outside of normal confines of biliary tree suggests leak ○ Sensitivity for bile leaks may approach 100% but is not accurate for defining exact site of leak or severity of injury (i.e., transection vs. partial tear)

Imaging Recommendations • Best imaging tool ○ Percutaneous transhepatic cholangiography (PTC) or ERCP: Gold standard for diagnosis of bile duct injuries

DIFFERENTIAL DIAGNOSIS Biliary Stricture Due to Nontraumatic Causes • Pancreatic ductal carcinoma ○ Pancreatic mass with pancreatic atrophy and pancreatic ductal dilatation • Cholangiocarcinoma ○ Small mass with abrupt biliary obstruction at confluence of right and left ducts or at common duct • Primary sclerosing cholangitis ○ Multifocal "beaded" strictures with alternating sites of stricture, normal ducts, and mildly dilated ducts ○ No history of trauma or surgery

947

Biliary System

Biliary Trauma

General Features • Etiology ○ Trauma: Can result from blunt or penetrating injuries – Tend to result from significant trauma with other injuries frequent (especially liver, spleen, and duodenum) – Most commonly injured site in biliary tree is GB □ GB injuries range in severity, including contusion, laceration, perforation, and GB avulsion (separation of GB from GB fossa) □ Isolated injury to GB rare due to protection from rib cage and liver, so almost always associated with other significant traumatic injuries □ Most common when GB is distended or after alcohol intake (distends GB by raising pressures at sphincter of Oddi) □ GB wall thickening or gallstones thought to be possibly protective □ GB ischemia and perforation due to traumatic arterial injury reported (very rare) – Injuries to intrahepatic ducts most common with liver lacerations ○ Iatrogenic – Most commonly after laparoscopic or open cholecystectomy – Other common sources of injury include □ Percutaneous liver biopsy or catheter placement □ Biliary tract exploration at surgery or ERCP □ Other upper abdominal operations (e.g., hepatic resection, gastrectomy) □ Hepatic artery chemoembolization (e.g., for hepatic metastases or primary carcinoma) – Iatrogenic injury occurs as result of technical errors or misidentification of biliary anatomy □ More common in setting of surgeon inexperience, cholecystitis, and aberrant anatomy – Injuries can include tears, transections, or ligations, and may be associated with bile leaks

Staging, Grading, & Classification • Strasberg classification most widely utilized to guide management ○ Type A: Leaks from minor duct (i.e., cystic duct or gallbladder fossa biliary radicle) in contiguity with CBD ○ Type B: Occlusion of injured right accessory duct still in contiguity with biliary tree ○ Type C: Bile leak from injured right accessory duct no longer in contiguity with biliary tree ○ Type D: Bile leak from common duct with no loss of continuity with rest of biliary tree ○ Type E: Complete transection of bile duct

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Virtually all patients with traumatic bile duct injury have other significant injuries that require attention

948

– Many patients with biliary strictures or bile leaks after blunt abdominal trauma may have delayed onset of symptoms, or symptoms may be attributed to other concomitant injuries – Symptoms may present days to weeks after initial trauma – Presentation may be due to obstructive jaundice, persistently elevated or rising bilirubin, or bile peritonitis ○ Postoperative bile duct injuries: May present early with obstructive jaundice or evidence of bile leak – In patients presenting months to years after surgery due to stricture, cholangitis is most common symptom – Complications recognized in 10-25% of patients with post-cholecystectomy injuries within 1st week □ Recognized in ~ 70% of patients within 1-6 months ○ Hemobilia: Triad of GI blood loss, biliary colic, and jaundice

PATHOLOGY

Demographics • Age ○ Iatrogenic and traumatic injuries more common in adults • Gender ○ Males: More likely to suffer traumatic injuries ○ Females: More iatrogenic injuries due to more frequent cholecystectomies • Epidemiology ○ Trauma-related injuries to biliary tree are rare, accounting for only 0.1% of all trauma admissions ○ Iatrogenic injuries more common, with ~ 2,500 bile duct injuries after cholecystectomy in United States – incidence over past decade with introduction of laparoscopic cholecystectomy □ Biliary injuries with laparoscopic cholecystectomy 2x more common than with open technique

Treatment • Traumatic GB injuries treated with cholecystectomy • Injuries detected intraoperatively during cholecystectomy should be repaired immediately • Minor bile duct injuries (including many intrahepatic ductal injuries) usually treated conservatively with ERCP stent placement or biliary drainage catheter to divert bile away from site of injury and allow time for healing • More severe injuries require surgical treatment (usually Roux-en-Y hepaticojejunostomy) after ERCP (or PTC) to assess injury and plan operative repair • Hemobilia: Conservatively treated if minor bleeding, but more severe hemobilia may require embolization or surgery

DIAGNOSTIC CHECKLIST Consider • High index of suspicion is mandatory in patients complaining of discomfort several days after surgery • Patients with major bile duct injuries should be evaluated for concomitant hepatic arterial injury

SELECTED REFERENCES 1.

Melamud K et al: Biliary imaging: multimodality approach to imaging of biliary injuries and their complications. Radiographics. 34(3):613-23, 2014

Biliary Trauma Biliary System

(Left) Cholangiogram in a patient after cholecystectomy demonstrates complete obstruction and contrast extravasation from the common hepatic duct , immediately adjacent to surgical clips, in keeping with an iatrogenic bile duct transection. (Right) Tc-99m HIDA scan shows foci of radiotracer accumulation outside of the biliary tree due to bile extravasation in a patient who had prior blunt trauma. HIDA scans are very sensitive and specific for bile leaks.

(Left) Axial CECT in a patient who had undergone recent cholecystectomy shows a large, loculated fluid collection in the gallbladder fossa, subsequently confirmed to be a biloma based on ultrasoundguided needle aspiration. (Right) ERCP in the same patient confirms extravasation of bile from the cystic duct remnant. Sphincterotomy was performed, and a plastic biliary stent was placed. The bile leak resolved, and the stent was removed subsequently without complication.

(Left) Axial CECT in a trauma patient shows a liver laceration and intraperitoneal free fluid. There is heterogeneous fluid and hematoma around the pancreatic head , near the expected position of the common bile duct. (Right) The same patient developed progressive abdominal pain and clinical signs suggestive of peritonitis. Concern about biliary injury prompted transhepatic cholangiography, which showed transection of the distal common bile duct within the pancreatic head, and extravasation of bile .

949

Biliary System

Chemotherapy-Induced Cholangitis KEY FACTS

• Iatrogenic cholangitis following intraarterial chemotherapy (hepatic artery infusion pump [HAIP] or transarterial chemoembolization [TACE]) for hepatic malignancies or metastases

○ Rarely causes peripheral intrahepatic strictures • CT or MR: Involved bile ducts may show periductal edema, mural thickening, and enhancement • Biloma formation (± abscess formation) may reflect druginduced necrosis of peripheral ducts

IMAGING

TOP DIFFERENTIAL DIAGNOSES

• Findings similar to primary sclerosing cholangitis, with stenosis or complete obstruction of involved ducts ○ ± dilation of upstream intrahepatic ducts, as associated periductal fibrosis may impede ductal dilatation • Distribution of strictures in biliary tree reflects hepatic arterial supply to bile ducts ○ Proximal extrahepatic duct and biliary confluence strictures are most common due to blood supply from hepatic artery ○ Distal extrahepatic duct is supplied by gastroduodenal artery branches, and consequently usually not involved ○ Gallbladder and cystic duct may be involved

• • • •

TERMINOLOGY

(Left) Axial CECT shows a liver metastasis that is low in attenuation, likely as a result of necrosis. Note the dilated ducts that resulted from a stricture of the biliary bifurcation and common hepatic duct, also due to chemotherapy. (Right) Transhepatic cholangiogram in the same patient shows gross dilation of the intrahepatic ducts, with abrupt, high-grade stenosis at the confluence of the right and left ducts. This patient had received floxuridine through an arterial catheter .

(Left) CECT of a patient with carcinoid liver metastases after 8 courses of TACE shows irregular right periductal low attenuation , pneumobilia, posterior segment atrophy, gastroesophageal varices , and ascites , compatible with chemotherapy-induced cholangitis and biliary cirrhosis. (Right) ERCP of the same patient shows a proximal common duct stricture and irregular, strictured intrahepatic ducts. A liver transplant was performed with cholangitis, bilomas, and biliary cirrhosis identified within the explant.

950

Primary sclerosing cholangitis Autoimmune cholangitis Extrinsic compression by liver masses or lymphadenopathy Chemical or drug-induced liver injury

PATHOLOGY • Results from either direct toxic effects of drug on biliary ducts or fibrosis/occlusion of peribiliary vascular plexus with resultant biliary ischemic cholangiopathy • Risk factors: Preexisting biliary strictures, prior biliary surgery, portal vein occlusion, nonselective placement of catheter during chemoembolization, higher doses of chemotherapy

Chemotherapy-Induced Cholangitis

Synonyms • Chemotherapy-induced sclerosing cholangitis (CISC); biliary sclerosis

Definitions • Iatrogenic cholangitis following intraarterial chemotherapy for hepatic malignancies or metastases ○ Complication of hepatic artery infusion pump (HAIP) or transarterial chemoembolization (TACE)

IMAGING General Features • Location ○ Distribution of strictures in biliary tree reflects hepatic arterial supply to bile ducts – Proximal extrahepatic duct and central intrahepatic ducts/biliary confluence are most commonly involved (~ 50%) due to blood supply from hepatic artery branches – Distal extrahepatic duct supplied by gastroduodenal artery branches, and consequently not usually involved – Rarely causes peripheral intrahepatic strictures – Gallbladder and cystic duct may be involved • Morphology ○ Findings similar to primary sclerosing cholangitis, with stenosis or complete obstruction of involved ducts – ± dilation of upstream intrahepatic ducts, as associated periductal fibrosis may impede ductal dilatation

Radiographic Findings • ERCP ○ Abnormalities range from minimal duct wall irregularity to marked duct wall thickening with near obliteration of lumen

CT Findings • CT (or MR) essential to differentiate cholangitis from extrinsic duct compression by lymph nodes or tumor • Mildly dilated intrahepatic bile ducts • Affected bile ducts may show periductal edema, mural thickening, and enhancement with adjacent fat stranding in hepatoduodenal ligament • Biloma formation (± abscess formation) may reflect druginduced necrosis of peripheral ducts

MR Findings • MRCP ○ Segmental strictures of variable length (similar to those seen in primary sclerosing cholangitis)

DIFFERENTIAL DIAGNOSIS Primary Sclerosing Cholangitis (PSC) • Multifocal "beaded" stenoses of intrahepatic and extrahepatic bile ducts with pruning, irregular wall thickening, and intervening sites of normal or dilated ducts • Associated with massive hypertrophy of caudate and marked peripheral liver atrophy in end-stage disease

Autoimmune Cholangitis • Imaging findings are almost identical to those of PSC

Extrinsic Compression by Liver Masses or Lymphadenopathy

Biliary System

TERMINOLOGY

• May compress extrahepatic or central intrahepatic ducts

Chemical or Drug-Induced Liver Injury • Can result in hepatitis, cholestasis, or both • Cholestatic pattern can result in injury to extrahepatic bile duct that is similar to PSC • Chronic involvement can result in "vanishing bile duct syndrome": Fibrosis and loss of intrahepatic ducts

PATHOLOGY General Features • Etiology ○ Results from either direct toxic effects of drug on biliary ducts or fibrosis/occlusion of peribiliary vascular plexus with resultant biliary ischemic cholangiopathy ○ Toxic effects of fluoropyrimidines (floxuridine and 5-FU) – Rarely from other drugs (e.g., mitomycin-C) ○ Risk factors – Preexisting biliary strictures, prior liver/biliary surgery, or portal vein occlusion – Nonselective placement of catheter during chemoembolization – Small diameter embolization agents or higher doses of infused chemotherapy agents

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Intermittent or progressive jaundice and cholestasis ○ Cholangitis (jaundice, pain, fever) ○ bilirubin, alkaline phosphatase

Demographics • Epidemiology ○ Cholangiographic abnormalities reported in 7-30% of patients undergoing intraarterial chemotherapy

Natural History & Prognosis • Complications: Acute hepatic failure, ischemic cholecystitis, biliary cirrhosis (rare)

Treatment • Reduction or cessation of intraarterial chemotherapy ○ Equivocal role of intraarterial steroids • Biliary decompression with endoscopic balloon dilation of strictures ± stenting • In rare cases, surgical resection of affected segment of bile duct or liver transplantation may be indicated

SELECTED REFERENCES 1.

Nguyen KD et al: Atypical causes of cholestasis. World J Gastroenterol. 20(28):9418-26, 2014

951

Biliary System

Gallbladder Polyps KEY FACTS

TERMINOLOGY

CLINICAL ISSUES

• Polypoid or sessile mass protruding from GB mucosa

• Size is most important predictor of malignancy ○ 100% of polyps > 20 mm are malignant ○ 43-77% of polyps 10-20 mm are malignant ○ 94% of benign polyps are < 10 mm • Risk factors for malignancy: Age > 60, gallstones, coexistence of primary sclerosing cholangitis (PSC) • Reassuring factors: Stability over time, multiple polyps, pedunculated (versus sessile) morphology • Current recommendations ○ Cholecystectomy if patient is symptomatic or has cholelithiasis or PSC (regardless of polyp size) ○ Polyp > 18-20 mm: Open cholecystectomy ○ Polyp 10-20 mm: Laparoscopic cholecystectomy ○ Polyp 6-9 mm: Serial follow-up at 3, 6, and 12 months ○ Polyp 5 mm: Serial imaging (no consensus; malignancy is extremely rare and some advocate no follow-up)

IMAGING • Ultrasound: Immobile echogenic mucosal nodule with no acoustic shadowing ○ Large polyps may show internal color flow vascularity ○ "Comet tail" artifacts suggest cholesterol polyp • CT: Useful for staging in larger polyps where risk of malignancy ○ Can show variable enhancement; no convincing correlation between enhancement and malignancy

TOP DIFFERENTIAL DIAGNOSES • • • • •

Tumefactive sludge Gallstone Polypoid GB carcinoma GB metastases Adenomyomatosis

(Left) Ultrasound of a 43-yearold woman with right upper quadrant pain shows mild gallbladder (GB) wall thickening and multiple small (< 5 mm), slightly echogenic polyps . An elective laparoscopic cholecystectomy for presumed biliary colic revealed cholesterolosis and cholesterol polyps. (Right) Ultrasound image shows multiple polyps in the GB that measure < 1 cm in size. While the data suggests nodules < 1 cm harbor a very low risk of malignancy, most society guidelines suggest imaging follow-up.

(Left) Ultrasound of a 41-yearold man with chest pain shows two 4-mm GB polyps . Their small size, echogenicity, multiplicity, and stability at follow-up sonography indicate hyperplastic (cholesterol) polyps. (Right) Ultrasound of a 47-year-old woman shows a 1cm, pathologically confirmed adenomatous polyp . The likelihood of neoplasia increases with polyp size, but most GB polyps are hyperplastic.

952

Gallbladder Polyps

Definitions • Polypoid or sessile mass protruding from gallbladder (GB) mucosa

IMAGING General Features • Best diagnostic clue ○ Nonmobile hyperechoic mass protruding from GB mucosa without acoustic shadowing • Location ○ GB lumen • Morphology ○ Sessile or pedunculated

Imaging Recommendations • Best imaging tool ○ Ultrasound; endoscopic ultrasound (EUS)

CT Findings • Often difficult to visualize on CT due to lower spatial resolution ○ CT underestimates polyp size compared to US • Best visualized on CECT due to vascularity of polyp ○ Can show variable enhancement ○ No convincing evidence that polyp enhancement pattern predicts malignancy • Ill-defined margins of larger polyps possible predictor of malignancy • Useful for local staging (including lymph node metastases, liver invasion, metastases) in larger polyps where risk of malignancy is high

Ultrasonographic Findings • Ultrasound is insensitive (only 50%) for polyps, detecting only 1/2 of polyps found at histopathology • False-positive rate of up to 30%, with positive predictive value of only 10% (compared to histopathology) ○ Poor accuracy rates for polyps < 5 mm ○ Potentially due to stones, GB folds, sludge, or cholesterolosis mimicking polyps ○ Roughly 10% of polyps disappear on follow-up ultrasounds – Original polyp may have been spurious, but could also reflect polyps breaking off or resolution of inflammatory polyps • Immobile echogenic mucosal excrescence/nodule, either sessile or lobulated ○ No acoustic shadowing, unlike stones ○ Highly echogenic foci or "comet tail" artifacts within polyp suggests a cholesterol polyp ○ Large polyps may show internal vascularity on color Doppler US ○ No clear sonographic features to differentiate benign and malignant polyps – Questionable link between sessile morphology and malignancy – Multiple nodules more likely to be benign (usually cholesterol polyps); neoplastic polyps often solitary

• EUS has been shown to have higher accuracy in differentiation of benign (97%) vs. malignant (76%) polyps ○ Better demonstration of mucosal invasion

Nuclear Medicine Findings • PET/CT ○ GB carcinoma has avid FDG uptake (relative to liver) ○ Some studies suggest role of PET in malignancy risk stratification of polyps 10-20 mm

Biliary System

TERMINOLOGY

DIFFERENTIAL DIAGNOSIS Tumefactive Sludge • Focal collection of sludge (cholesterol or calcium bilirubinate crystals) appearing polypoid or mass-like • No acoustic shadowing or internal flow on color Doppler imaging • Sludge will slowly move when altering patient position during scanning

Gallstone • Posterior acoustic shadowing • "Twinkling" artifact with color Doppler US • Freely mobile within GB unless impacted

Polypoid GB Carcinoma • Typically larger than adenoma, most often > 15 mm • May cause focal loss of wall reflectivity due to mural invasion • Internal flow often detectable with color Doppler US • Porta hepatis adenopathy &/or direct liver invasion • Often associated with stones

GB Metastases • Melanoma most common • Enhancing polypoid mass in setting of widespread metastatic disease

Adenomyomatosis • Can be nodular and mass-like, but usually associated with "comet-tail" artifact

PATHOLOGY General Features • Etiology ○ Unknown • Genetics ○ GB adenomas associated with familial adenomatous polyposis and Peutz-Jeghers syndrome

Staging, Grading, & Classification • Neoplastic polyps ○ Adenoma – Benign – Accounts for 0.5-4% of polyps – Solitary, usually in range of 5-20 mm – Often associated with gallstones – Progression to adenocarcinoma is yet unclear; adenoma-carcinoma sequence seen in colon cancer has not been defined for GB □ Not clear that GB cancers arise from adenomas ○ Adenocarcinoma 953

Biliary System

Gallbladder Polyps

– 15-25% of GB adenocarcinomas present as polypoid lesions – Solitary, usually > 1 cm (in 1 study 88% were > 1 cm) – May have thickened implantation base or evidence of mucosal invasion ○ Rare benign lesions: Leiomyoma, lipoma, neurofibroma, carcinoid ○ Rare malignant lesions: Squamous cell carcinoma, mucinous cystadenocarcinoma • Nonneoplastic polyps ○ Majority (> 95%) of cases ○ Cholesterol polyps – 1/3 of cases in cholesterolosis are polypoid, the rest manifest as diffuse nodularity of GB – Accounts for 60% of all polyps – Infiltration of mucosa and lamina propria with lipidladen foamy macrophages – Multiple, < 10 mm ○ Adenomyomatosis – Localized (focal) adenomyomatosis can mimic polyps – Accounts for 25% of polyps – Usually seen in fundus, usually 10-20 mm – Excessive epithelial proliferation with invagination into muscular layer ○ Inflammatory polyps – Accounts for 10% of polyps – Result from granulation and fibrous tissue secondary to chronic inflammation – Sessile or pedunculated, usually < 10 mm ○ Choristoma (rare): Heterotopic gastric, pancreatic, or hepatic tissue

Microscopic Features • Adenomas may be tubular, papillary, or tubulopapillary ○ Tubular adenoma most common variant – Covered with biliary epithelium, composed of pyloric or intestinal-type glands • Cholesterol polyp composed of sheets of lipid-laden macrophages with normal overlying GB mucosa

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most are asymptomatic • Other signs/symptoms ○ Debatable association with chronic dyspepsia ○ Cholesterol polyps can detach and behave like stones – Can cause biliary colic, obstruction, pancreatitis ○ Lab markers: CEA and CA19-9 have no role in differentiating benign and malignant polyps

Demographics • Epidemiology ○ Prevalence varies by demographics of studied population – 1.5-5% in abdominal ultrasounds – 0.005-13.8% of resected GBs ○ No consistent relationship with age, gender, or obesity ○ 1 study showed inverse relationship with stones

954

– May be harder to diagnose polyps in presence of cholelithiasis

Natural History & Prognosis • Natural history and management of polyps has been an area of great debate, with no management consensus • Large prospective study of incidental polyps < 10 mm showed no change in size in 2- and 5-year follow-ups • Retrospective study of 346 incidental polyps demonstrated growth in only 1% of cases; no lesions < 6 mm were neoplastic • Risk factors for malignancy ○ Proposed risk factors for malignancy include: Age > 60 years, gallstone, coexistence of primary sclerosing cholangitis (PSC), and irregular GB wall thickening or sessile morphology of polyp on US – Other concerning features: Irregular GB wall thickening and sessile morphology of polyp ○ Size is most useful predictor of malignancy – 100% of polyps > 20 mm are malignant (either invasive carcinoma or high-grade dysplasia) – 43-77% of polyps 10-20 mm are malignant – 94% of benign polyps are < 10 mm; 88% of malignant polyps are > 10 mm – Although older studies suggested a cut-off value of 10 mm for safely differentiating benign from malignant polyps, some studies propose changing cut-off to 6 mm for reaching 100% sensitivity (albeit in cost of lower specificity) ○ Reassuring factors: Stability over time, multiple polyps, pedunculated (versus sessile)

Treatment • No consensus exists regarding management of polyps ○ Recommendations vary among different specialty societies • Current recommendations ○ Cholecystectomy if patient is symptomatic or if there is coexisting gallstone or PSC (regardless of size of polyp) ○ Polyp > 18-20 mm: CT, PET, &/or EUS for preoperative staging open cholecystectomy with possible resection of adjacent liver tissue ○ Polyp 10-20 mm: Cholecystectomy ○ Polyp 6-9 mm: Serial follow-up imaging in 3, 6, and 12 months (no consensus on frequency of follow-up) ○ Polyp 5 mm: Serial imaging (no consensus; malignancy is extremely rare in this group and some recommend no follow-up)

DIAGNOSTIC CHECKLIST Consider • Size is most important predictor of malignancy • Although risk of malignancy in small (< 6 mm) polyps is extremely low, some guidelines still recommend surveillance ultrasound

SELECTED REFERENCES 1.

Wiles R et al: Growth rate and malignant potential of small gallbladder polyps - Systematic review of evidence. Surgeon. 12(4):221-226, 2014

Gallbladder Polyps Biliary System

(Left) Ultrasound of a 43-yearold man shows 2 tiny GB polyps . Assessment of mobility during real-time examination helps to differentiate between polyps and small, nonshadowing stones or sludge. (Right) Axial T2WI FS MR of the same patient shows two GB polyps . These incidental polyps were stable 2 years later. Although tiny polyps are rarely malignant, ultrasound surveillance is typically advocated. How long and at what interval these small polyps should be followed is controversial.

(Left) Ultrasound of a 55-yearold woman shows a 1.8 cm polyp within the GB fundus. Loss of reflectivity of the adjacent GB wall might suggest a neoplastic polyp. This and the size of the polyp prompted elective cholecystectomy, which revealed a solitary but large cholesterol polyp. (Right) Axial CECT of the same patient shows an enhancing, nondependent lesion within the GB fundus. The lack of transmural invasion at CT prompted a laparoscopic, rather than open, cholecystectomy.

(Left) Ultrasound of a 55-yearold woman with right upper quadrant pain shows a > 2 cm sessile polypoid GB lesion . Laparoscopic cholecystectomy was performed because of the patient's symptoms and the size/configuration of the polyp. (Right) Axial CECT of the same patient shows focal thickening of the GB wall and no obvious transmural disease. An invasive GB adenocarcinoma was identified at pathology. Early stage, incidental GB carcinoma often appears as a sessile polyp at imaging.

955

Biliary System

Gallbladder Carcinoma KEY FACTS

• CT and MR findings ○ Several different possible imaging appearances – Mass completely replacing gallbladder (GB) (2/3 of cases) – Irregular focal or diffuse GB wall thickening (20-30%) – Intraluminal polyploid GB mass (~ 20% of cases) ○ Typically hypodense on venous phase, but may have peripheral vascularity on arterial phase ○ Frequently invades liver and porta hepatis ○ Bulky porta hepatis/paraaortic adenopathy common ○ Most common sites of metastasis: Liver and peritoneum ○ Calcified gallstones or porcelain GB may be present • US findings ○ Asymmetric GB wall thickening or a discrete polyploid, heterogeneous, moderately echogenic GB mass ○ Hepatic invasion with loss of normal echogenic GB wall dividing mass from liver

(Left) Schematic drawing of gallbladder (GB) carcinoma shows gallstones and a focal mural mass arising from the GB wall, invading the adjacent liver and obstructing the common hepatic duct. (Right) Coronal CECT demonstrates a soft tissue mass arising from the GB and extending superiorly to invade the liver and porta hepatis. Note the presence of multiple gallstones , a known major risk factor for GB carcinoma.

(Left) Axial CECT demonstrates a large, enhancing polyploid mass in the GB, in keeping with GB carcinoma. Such polyploid masses only account for roughly 20% of all GB cancers detected on CT. (Right) Ultrasound demonstrates a soft tissue mass filling the GB fundus, in keeping with a GB carcinoma. Note that the echogenic GB wall is intact between the mass and liver, suggesting that there is no liver invasion.

956

○ Internal color flow vascularity on color Doppler

IMAGING

TOP DIFFERENTIAL DIAGNOSES • • • •

Complicated or chronic cholecystitis Xanthogranulomatous cholecystitis Metastatic disease to gallbladder Gallbladder polyp or adenomyomatosis

PATHOLOGY • Major risk factors: Cholelithiasis, chronic cholecystitis, porcelain GB, and GB polyps

CLINICAL ISSUES • Most common in elderly female patients • Many patients are asymptomatic, with incidental diagnosis after cholecystectomy for gallstones or cholecystitis • Very poor prognosis: 5-year survival rate of 4% ○ 75% of patients have metastases at time of diagnosis • T stage determines surgical approach (simple or extended cholecystectomy ± radical resection (liver, colon, etc.)

Gallbladder Carcinoma

Definitions • Malignant epithelial neoplasm arising from gallbladder (GB) mucosa

IMAGING General Features • Best diagnostic clue ○ Large GB mass completely replacing the gallbladder and extending into liver ○ Polypoid mass within GB lumen ○ Diffuse or focal irregular gallbladder wall thickening

Radiographic Findings • ERCP ○ Limited utility since GB is usually nonvisualized ○ May demonstrate common hepatic duct obstruction with dilated intrahepatic ducts

CT Findings • Accuracy of CT for GB cancer between 84-92% • Intraluminal polyploid GB mass (~ 20% of cases), irregular focal or diffuse GB wall thickening (20-30% of cases), or mass completely replacing GB (2/3 of cases) ○ May be difficult to differentiate from primary liver mass when large mass replaces GB and invades liver ○ May be difficult to differentiate from Klatskin tumor (cholangiocarcinoma) when tumor invades porta hepatis ○ GB cancer presenting as wall thickening (especially when diffuse) difficult to differentiate from chronic cholecystitis; look for irregular wall thickening, metastases, and locoregional enlarged lymph nodes ○ Typically a hypodense mass on portal venous phase, but may have peripheral vascularity on arterial phase – 2-layer pattern of enhancement in thickened GB wall (hypoenhancing outer layer and hyperemic inner layer) – May have calcifications (possibly engulfed gallstones) and cystic components (usually mucinous tumors) • Frequent invasion of liver and porta hepatis • Bulky porta hepatis and paraaortic lymphadenopathy common • Most common sites of metastasis: Liver (either via direct invasion or hematogenous metastases) and peritoneum (usually in RUQ omentum) • Calcified gallstones or porcelain GB may be present

MR Findings • MR findings parallel CT in terms of tumor morphology • GB carcinoma usually T1 hypointense, T2 intermediate to hyperintense, and hypoenhancing on T1WI C+ images • MR may provide some value for T-staging and may be slightly more sensitive than CT for early liver invasion • Malignant GB lesions often show restricted diffusion

Ultrasonographic Findings • Asymmetric GB wall thickening or a discrete polyploid, heterogeneous, moderately echogenic GB mass ○ Mass may completely replace the GB making it difficult to establish site of origin

○ Frequent hepatic invasion with loss of normal echogenic GB wall dividing mass from liver • Should be immobile when patient positioning is altered • Associated with gallstones and porcelain GB • Usually associated with internal color flow vascularity on color Doppler ultrasound ○ Lack of vascularity cannot exclude malignancy when confronted with suspicious wall thickening or mass

Biliary System

TERMINOLOGY

Nuclear Medicine Findings • Hepatobiliary scan: Nonfilling of GB can mimic cholecystitis • PET/CT: Most GB cancers are FDG avid, although role for PET/CT in preoperative evaluation is unclear ○ May identify occult metastases and change management in ~ 20%

Imaging Recommendations • Best imaging tool ○ US, CECT, MR

DIFFERENTIAL DIAGNOSIS Complicated or Chronic Cholecystitis • Contracted, thick-walled, hyperemic gallbladder (frequently associated with gallstones) ± pericholecystic abscess • May be indistinguishable from carcinoma based on imaging

Xanthogranulomatous Cholecystitis • Rare form of GB inflammation characterized by accumulation of lipid-laden macrophages and fibrous tissue • Usually requires histologic examination to differentiate from GB carcinoma

Metastatic Disease to GB or GB Fossa • Melanoma may directly metastasize to GB mucosa and present as an intraluminal mass or focal thickening • Hepatocellular carcinoma and other hepatic tumors may secondarily invade GB • Several tumors may spread to porta hepatis lymph nodes (especially GI tract malignancies and lymphoma) and mimic pattern of spread for GB carcinoma

GB Polyp • Nonshadowing, moderately echogenic, nonmobile mucosal mass ± internal color flow vascularity on Doppler • Risk of malignancy directly related to polyp size: Most polyps under 1 cm have low risk of malignancy

Adenomyomatosis • Localized or diffuse gallbladder wall thickening with "comet tail" artifact • May rarely present as discrete mass at fundus

PATHOLOGY General Features • Etiology ○ Risk factors (mostly related to chronic GB inflammation): Cholelithiasis, chronic cholecystitis, chronic infection (Salmonella), porcelain GB, GB polyps, abnormal pancreaticobiliary duct junction (seen with choledochal cysts), obesity – 70-90% have cholelithiasis, which is strongly associated with GB carcinoma 957

Biliary System

Gallbladder Carcinoma

risk with larger stones (> 3 cm increases risk by 10x) and long duration of gallstone disease – Strength of association between porcelain GB and GB carcinoma is controversial, although likely greater risk with irregular, discontinuous GB wall calcification – Highest risk of GB carcinoma with GB polyps > 2 cm – Abnormal pancreaticobiliary junction (with pancreatic duct directly draining into common bile duct) increases risk of GB carcinoma even in absence of choledochal cyst □ Major risk for GB carcinoma in Asian populations • Genetics ○ Adenoma-carcinoma sequence in GB carcinoma is less certain compared to colon cancer – KRAS and CTNNB1 gene mutations may play a role, with possible familial predilection for GB cancer • Associated abnormalities ○ Ulcerative colitis, rarely Crohn disease ○ Primary sclerosing cholangitis ○ Familial polyposis coli

Staging, Grading, & Classification • Nevin staging system ○ Stage I: Carcinoma confined to mucosa ○ Stage II: Mucosal and muscularis involvement ○ Stage III: Serosal extension ○ Stage IV: Transmural involvement with positive cystic duct nodes ○ Stage V: Invasion into liver, distant organ metastasis, or nodal metastases • AJCC TNM staging system ○ Preferred staging system: Better correlation with prognosis (particularly T stage, which has high correlation with prognosis and treatment) ○ Strong correlation between lymph node/distant metastases and patient's T stage ○ T1 tumors: Confined to lamina propria or muscular layer of GB wall ○ T2 tumors: Extending into perimuscular connective tissue (but not serosa) ○ T3 tumors: Extends beyond GB wall into serosa, liver, or other adjacent organs ○ T4 tumors: Tumor invades main portal vein, hepatic artery, or 2 extrahepatic structures/organs

bilirubin/alkaline phosphatase with biliary obstruction

Demographics • Age ○ Usually elderly patients (mean 65 years) • Gender ○ M:F = 1:3 • Epidemiology ○ Wide geographic variability paralleling prevalence of cholelithiasis and biliary tract infections – Higher incidences in South America and Asia ○ 6th most common GI cancer and most common biliary tract malignancy – Incidence of 1-2 cases per 100,000 people – 6,500 deaths per year in USA – 9x more common than extrahepatic cholangiocarcinoma

Natural History & Prognosis • Spreads by local invasion to liver, nodal spread to porta hepatis and paraaortic nodes, and hematogenous spread to liver and peritoneum • Very poor prognosis: 5-year survival rate of 4% ○ 75% of patients have metastases at time of diagnosis ○ Median survival for stage I-III: 12 months ○ Median survival for stage IV: 6 months

Treatment • Stage I or II (T1-T2, N0, M0) tumors resectable with curative intent; stage III tumors (T3 or T1-2, N1) usually (but not always) unresectable; stage IV almost always unresectable (T4 or N2 or M1) • T stage critical for determining surgical approach ○ T1 lesions treated with simple cholecystectomy ○ T2 lesions: Extended cholecystectomy (GB removed with portions of liver around GB fossa) – If detected incidentally, repeat surgery needed to assess for residual disease (T2/T3 tumors) ○ T3 or T4 tumors: Extended cholecystectomy ± further resection (liver, colon, etc.) for local invasion • Unresectable cancers (due to local invasion or metastatic disease) treated with stent for palliation of biliary obstruction and systemic chemotherapy

DIAGNOSTIC CHECKLIST

Microscopic Features

Consider

• 90% are adenocarcinoma • Less common subtypes include squamous, adenosquamous, small cell, lymphoma, and sarcoma

• GB cancer when confronted by large mass replacing GB and invading liver • GB cancer when confronted by bulky porta hepatis and paraaortic lymphadenopathy or carcinomatosis (especially in RUQ)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Many patients are asymptomatic, with incidental diagnosis of tumor on pathologic examination after cholecystectomy for gallstones or cholecystitis – May account for ~ 50% of all diagnosed GB cancers ○ Patient symptoms include RUQ pain, anorexia, nausea, vomiting, weight loss, and jaundice • Clinical profile ○ CEA and CA19-9 (lack sensitivity and specificity) 958

○

□

SELECTED REFERENCES 1.

Mitchell CH et al: Features suggestive of gallbladder malignancy: analysis of T1, T2, and T3 tumors on cross-sectional imaging. J Comput Assist Tomogr. 38(2):235-41, 2014

Gallbladder Carcinoma Biliary System

(Left) Axial CECT demonstrates a GB cancer invading both the liver and the adjacent descending duodenum . If considered resectable, such a cancer would undoubtedly require an extended cholecystectomy with radical resection. (Right) Axial CECT demonstrates a mass in the GB fossa directly invading the liver . In many cases, such as this, the site of origin for the mass can be difficult to determine.

(Left) Axial CECT shows extensive circumferential wall thickening of the GB. This was prospectively felt to represent xanthogranulomatous cholecystitis, but was found to be GB carcinoma at surgery. (Right) Ultrasound image shows a GB fossa mass and a shadowing stone . The mass is inseparable from the adjacent liver. CT (not shown) demonstrated local invasion of the central liver by GB carcinoma.

(Left) Axial CECT shows marked irregular GB wall thickening , direct liver invasion , and peripancreatic/portocaval and retroperitoneal adenopathy. Bulky lymphadenopathy in these locations is typical for GB carcinoma. (Right) Axial CECT demonstrates a large hepatic hypodense mass. While a primary hepatic tumor is possible, note the gallstone at its center and the failure to visualize a GB. This was a GB cancer with extensive invasion of the liver.

959

Biliary System

Ampullary Carcinoma KEY FACTS

TERMINOLOGY • Heterogeneous group of malignant epithelial neoplasms (adenocarcinoma) arising from ampulla of Vater

• Distal CBD cholangiocarcinoma • Periampullary duodenal carcinoma • Ampullary carcinoid tumor

IMAGING

PATHOLOGY

• CT: Hypodense mass centered in ampulla ○ Well defined/lobulated or poorly marginated ○ Almost always obstructs common bile duct (CBD) ○ Pancreatic duct (PD) obstructed in only ~ 50%, and usually does not cause upstream pancreatic atrophy ○ Small masses often not visualized on CT • MR: Low signal on T1WI, intermediate signal on T2WI, and hypoenhancing on T1WI C+ ○ Diffusion-weighted images may increase sensitivity for small masses

• Markedly increased incidence in hereditary polyposis syndromes • Lesions can be divided into 3 forms ○ Tumors arising from duodenal epithelium (intestinal type): Prognosis comparable to duodenal carcinoma ○ Tumors arising from pancreaticobiliary epithelium of distal CBD/PD (pancreaticobiliary type): Worst prognosis, with outcomes similar to pancreatic adenocarcinoma ○ Intraampullary tumors: Best prognosis with early ductal obstruction and consequent early presentation

TOP DIFFERENTIAL DIAGNOSES

CLINICAL ISSUES

• Pancreatic head adenocarcinoma involving ampulla • Ampullary adenoma

• Obstructive jaundice (80%) most common symptom • Same surgical treatment (Whipple procedure) as for all periampullary neoplasms

(Left) Graphic shows ampullary carcinoma causing obstruction of both the common bile duct (CBD) and the pancreatic duct (PD) . (Right) ERCP in a patient with a history of familial polyposis shows a small mass causing obstruction of the distal common duct at the ampulla. Patients with familial polyposis have a substantially increased risk of developing ampullary (and other) carcinomas. Lifelong surveillance is required to detect bowel, stomach, and biliary tumors.

(Left) Coronal CECT demonstrates a classic doubleduct sign caused by an ampullary carcinoma , with obstruction of both the common bile duct and pancreatic duct . Note the abrupt occlusion of both ducts by the mass. (Right) Coronal CECT demonstrates a lobulated mass centered at the ampulla obstructing the pancreatic and common bile ducts. While this was a pancreaticobiliary type lesion at histology, individual subtypes of ampullary carcinoma cannot be distinguished on imaging.

960

Ampullary Carcinoma

Definitions • Heterogeneous group of malignant epithelial neoplasms (adenocarcinoma) arising from ampulla of Vater

IMAGING General Features • Best diagnostic clue ○ Soft tissue mass centered in ampulla ○ Double duct sign with obstruction of both common bile duct (CBD) and pancreatic duct (PD) • Location ○ Centered in region of ampulla of Vater or overlying periampullary duodenal mucosa • Morphology ○ Can be either well-defined lobulated mass or more infiltrative and ill defined

CT Findings • Mass with variable attenuation (most often hypodense) centered in ampulla ○ Almost always obstructs CBD with abrupt cut-off of CBD by mass ○ PD obstructed in only ~ 50% of cases, with ampullary tumors much less likely than pancreatic cancer to cause upstream pancreatic atrophy • Small masses may not be visualized on CT (or any other radiological imaging modality) ○ Secondary signs suggest presence of tumor (e.g., doubleduct sign, irregular obstructed duct, etc.) • Most common sites of metastases: Lymph nodes or liver

MR Findings • Typically low signal on T1WI, intermediate to high signal on T2WI, and hypoenhancing relative to pancreas on T1WI C+ • CBD ± PD dilatation with abrupt ductal cutoff ○ MRCP: Abrupt, irregular cut-off of distal CBD • Diffusion-weighted images may increase sensitivity for small masses (malignant ampullary tumors have lower ADC values than benign lesions)

Ultrasonographic Findings • Grayscale ultrasound ○ May be useful as initial screening tool for detection of biliary dilation in patients presenting with jaundice ○ Distal CBD and PD can be difficult to visualize as a result of bowel gas – Ampullary mass almost never visible on US • Endoscopic US ○ Tumors usually visible endoscopically, but endoscopic US may help guide biopsy and improve biopsy yields ○ Best modality for T staging (accuracy up to 90%) ○ May help detect and biopsy nodal metastases

Radiographic Findings • ERCP ○ Ampullary mass should be readily visible under endoscopy in most cases and can be easily biopsied – Superior to CT in detecting small tumors

○ Cholangiography demonstrates obstruction of CBD and PD with abrupt cut-off at mass

Fluoroscopic Findings • Upper GI series: Filling defect in 2nd portion of duodenum in region of ampulla of Vater ○ No specific features to differentiate ampullary tumor from pancreatic or duodenal malignancy

Biliary System

TERMINOLOGY

Imaging Recommendations • Best imaging tool ○ CECT with dedicated biphasic pancreatic protocol or MR with MRCP • Protocol advice ○ Patients drink 500 cc water immediately prior to CT to distend duodenum (improving visualization of ampulla) ○ Dual-phase acquisition (arterial and venous phases) critical for improving visualization of tumor – Lesions may be more or less conspicuous on each phase ○ Coronal multiplanar reformats (MPR) and curved planar reformats helpful for assessing distal CBD and differentiating malignant from benign obstruction

DIFFERENTIAL DIAGNOSIS Pancreatic Head Adenocarcinoma Involving Ampulla • Hypoattenuating, infiltrative mass with obstruction of both CBD and PD and involvement of retroperitoneal vasculature • Frequent upstream pancreatic atrophy (less common with ampullary carcinoma)

Ampullary Adenoma • Benign lesion which may be precursor to ampullary carcinoma • Indistinguishable from carcinoma on CT, with slightly lower incidence of severe ductal obstruction

Distal CBD Cholangiocarcinoma • 20% of all cholangiocarcinomas occur in distal 1/3 of CBD • May demonstrate some hypervascularity on arterial phase and delayed enhancement on CECT/MR • Usually asymmetric wall thickening/enhancement of CBD, but can present as discrete mass • Biliary obstruction with abrupt cut-off at level of mass • Worse prognosis than ampullary adenocarcinoma

Periampullary Duodenal Carcinoma • Duodenum most common site for small bowel adenocarcinoma • Large duodenal carcinomas may invade ampulla or pancreas and result in ductal obstruction, but ductal obstruction (either PD or CBD) is less common than with ampullary tumors

Ampullary Carcinoid Tumor • Rare tumor that is avidly hypervascular on arterial phase CECT • Predisposition for early lymph node and distant metastases, even when primary lesion is quite small

961

Biliary System

Ampullary Carcinoma

General Features • Etiology ○ Proposed adenoma to adenocarcinoma carcinogenesis sequence (similar to colorectal cancer) – 60% of adenomas contain foci of invasive carcinoma – Ampullary adenomas cannot be differentiated from invasive carcinoma on imaging ○ Significant tumor heterogeneity, as lesions can be divided into 3 forms, which cannot be differentiated on imaging – Tumors arising from duodenal epithelium of ampulla (intestinal type) □ Large at presentation with early lymph node metastases □ Prognosis comparable to duodenal carcinoma – Tumors arising from pancreaticobiliary epithelium of distal CBD or pancreatic duct (pancreaticobiliary type) □ Worst prognosis of 3 types, with biologic behavior similar to pancreatic adenocarcinoma – Intraampullary tumors with combined duodenal and pancreaticobiliary epithelial origin □ Best prognosis because of origin within ampulla, resulting in early ductal obstruction and early presentation with jaundice □ Less likely to demonstrate significant invasive component • Genetics ○ Markedly increased incidence in hereditary polyposis syndromes (e.g., familial adenomatosis coli, hereditary nonpolyposis colon cancer, etc.)

Staging, Grading, & Classification • TNM staging system related to nodal and distant metastases ○ Nodal metastases outside of peripancreatic region considered M1 lesion ○ T1: Lesion confined to ampulla ○ T2: Tumor invading duodenal wall ○ T3: Pancreatic invasion < 2 cm deep ○ T4: Pancreatic invasion > 2 cm deep

Microscopic Features • Malignant ductal epithelial cells with varying degrees of differentiation and necrosis • Spectrum of histology: Dysplasia, carcinoma in situ, frank adenocarcinoma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Obstructive jaundice (80%) most common symptom as nearly all patients have CBD obstruction ○ Weight loss (61%), abdominal pain, back pain (46%) • Other signs/symptoms ○ GI bleeding with heme-positive stool ○ Diarrhea or steatorrhea ○ Nausea, dyspepsia ○ Fever and chills from cholangitis • Clinical profile 962

○ bilirubin and alkaline phosphatase ○ May have CEA or CA19-9 tumor markers – Neither sensitive nor specific for presence of tumor – preoperative tumor markers associated with poor outcome

PATHOLOGY

Demographics • Age ○ Average age at diagnosis is 65 years (earlier in patients with hereditary polyposis syndromes) • Gender ○ M:F = 2:1 • Epidemiology ○ Rare tumor representing 0.2% of GI tract malignancies and 6% of periampullary lesions ○ Incidence: 4-6 per 1 million population ○ Associated with smoking (30%) and diabetes (17%)

Natural History & Prognosis • Depends on histologic type of tumor, as well as nodal and distant metastases at presentation • Prognosis ○ Better than periampullary carcinoma of biliary or pancreatic origin ○ Slightly worse than periampullary duodenal carcinoma ○ Reported 5-year survival of 64-80% in node-negative patients and 17-50% in node-positive cases ○ Best odds of survival: Negative surgical margins, negative nodes, well-differentiated tumors

Treatment • Preoperative treatment of biliary obstruction with ERCP stent placement • Pancreatoduodenectomy (Whipple procedure, either classic or pylorus-preserving) in patients with good operative risk • Local resection (ampullectomy) associated with higher risk of local recurrence and worse long-term survival ○ Might be an option in patients with noninvasive tumors with low risk of lymph node metastases

DIAGNOSTIC CHECKLIST Consider • Differentiation of ampullary carcinomas from other periampullary tumors (e.g., pancreatic or duodenal adenocarcinoma) may be difficult, but surgical treatment (Whipple procedure) is the same

Image Interpretation Pearls • Adequate distension of duodenum with water on CECT is key to identifying ampullary mass • Small ampullary tumors can be very difficult to visualize on CECT or MR, and secondary signs (e.g., double duct sign) should suggest presence of occult tumor

SELECTED REFERENCES 1.

Raman SP et al: Abnormalities of the Distal Common Bile Duct and Ampulla: Diagnostic Approach and Differential Diagnosis Using Multiplanar Reformations and 3D Imaging. AJR Am J Roentgenol. 203(1):17-28, 2014

Ampullary Carcinoma Biliary System

(Left) Coronal CECT demonstrates a polypoid mass centered at the ampulla, representing an ampullary carcinoma. A biliary stent is partially visualized. The coronal plane is usually the best way of visualizing the ampulla and assessing a potential mass. (Right) Coronal CECT demonstrates an ill-defined hypodense ampullary mass obstructing the common bile duct , with only mild dilatation of the pancreatic duct . This was found to represent an ampullary carcinoma at surgery.

(Left) Coronal volumerendered CECT demonstrates a double-duct sign with obstruction of the common bile duct and pancreatic duct by a polypoid ampullary carcinoma . (Right) Coronal CECT shows a discrete mass centered around the ampulla with a biliary stent . Ampullary carcinoma cannot be easily distinguished from a periampullary duodenal carcinoma at imaging, although surgical treatment for both lesions is the same (Whipple procedure).

(Left) Coronal CECT demonstrates a rounded, welldefined ampullary mass obstructing the CBD . The PD (not shown) was not obstructed. Ampullary carcinomas almost always obstruct the CBD, but obstruct the PD in only 50% of cases. (Right) Axial CECT demonstrates an invasive adenocarcinoma of the ampulla of Vater arising from a villous adenoma. Note the large, circumferential or "apple core" mass at the junction of the 2nd and 3rd portions of the duodenum.

963

Biliary System

Biliary Metastases and Lymphoma KEY FACTS

IMAGING • Metastases to gallbladder (GB) ○ CT: Usually polyploid enhancing nodule or mass within GB lumen, but may appear as focal mural thickening ○ MR: Melanoma classically hyperintense on T1WI and hypointense on T2WI ○ US: Immobile polypoid mass (usually > 1.5 cm) ± adjacent GB wall thickening – Melanoma classically described as hyperechoic, without acoustic shadowing – May be single or multiple – Flow characteristics variable on color Doppler, but usually evidence of internal flow • Lymphoma of GB ○ High-grade lymphomas often present as bulky mass (usually hypodense and homogeneous), while low-grade lymphomas cause only mild wall thickening ○ Usually other evidence of lymphoma elsewhere, including adenopathy and splenomegaly

(Left) Axial CECT in a melanoma patient reveals a gallbladder metastasis , as well as a larger rounded left lower lobe pulmonary metastasis . Melanoma is the most common primary malignancy to metastasize to the gallbladder. (Right) Color Doppler ultrasound demonstrates a hypoechoic rounded nodule in the gallbladder with internal color flow vascularity. While a large polyp or gallbladder cancer could also be considered, this was a melanoma metastasis.

(Left) Axial CECT in a patient with weight loss and jaundice shows a soft tissue mass within the gallbladder along with gallstones . Also noted is massive lymphadenopathy , all due to non-Hodgkin lymphoma. (Right) Coronal CECT demonstrates a subtle soft tissue nodule arising in the common duct with thickening/hyperenhancement of the more proximal duct. While this could certainly represent a cholangiocarcinoma, this was a metastasis from colon cancer.

964

• Metastatic disease to biliary tree ○ Indistinguishable from cholangiocarcinoma, including bile duct wall thickening, discrete soft tissue mass in porta hepatis, and proximal biliary dilatation/obstruction

PATHOLOGY • Metastases to GB are rare, representing < 5% of all GB malignancies ○ Melanoma accounts for 50-67% of GB metastases, with lung and renal malignancies also common ○ Most patients with GB metastases have end-stage disease with widespread metastatic disease ○ May rarely cause cholecystitis (due to cystic duct obstruction) or jaundice • GB lymphoma represents only 0.1% of GB cancers ○ Almost always secondary lymphomatous involvement, with primary GB lymphoma extraordinarily rare • Metastases to biliary tree are rare, with colon cancer most common (propensity for spread along epithelial surfaces)

Biliary Papillomatosis

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Rare disorder characterized by multiple premalignant adenomatous papillary tumors in intrahepatic or extrahepatic biliary tree

• Choledocholithiasis, cholangiocarcinoma, pneumobilia, hepatocellular carcinoma

IMAGING

• Possibly incited by chronic inflammation from choledocholithiasis, infection, or pancreatic juice reflux • Frequently associated with cholelithiasis, choledocholithiasis, choledochal cyst, cirrhosis

• Cholangiogram: Multiple round or oval filling defects in biliary tree with irregularity of adjacent bile duct wall ○ Can be found in intrahepatic or extrahepatic ducts and range in size from a few mm (most common) to a few cm ○ Tumors may secrete mucin: Wide-open ampulla of Vater with extrusion of mucoid material on ERCP • CT and MR: Biliary ductal dilatation due to obstruction &/or increased mucin production ○ Hypodense, nonenhancing intraductal mass on CECT ○ T1 hypointense, mildly T2 hyperintense on MR ○ Multiple round or oval signal voids within dilated ducts on MRCP with serrated appearance of duct wall • US: Polypoid nodules without acoustic shadowing

PATHOLOGY

Biliary System

KEY FACTS

CLINICAL ISSUES • Patients present with repeated episodes of abdominal pain, jaundice, and acute cholangitis • Most common in older (6th-7th decades) male patients • High propensity for malignant transformation with up to 83% of patients having adenocarcinoma at diagnosis • Treatment is surgical resection of tumor (usually partial hepatectomy) or liver transplantation in patients with diffuse involvement of ducts

(Left) ERCP of a patient with elevated liver function tests shows polypoid filling defects within the extrahepatic duct. Mild dysplasia was identified at resection. Biliary papillomatosis (like biliary IPMN) is considered a premalignant lesion and is often frankly invasive at diagnosis. (Courtesy M. Kanematsu, MD.) (Right) MIP MRCP image in the same patient demonstrates the multiple nodules appearing as low-signal filling defects within the duct. (Courtesy M. Kanematsu, MD.)

(Left) MRCP of a patient with jaundice shows multiple small common and anterior segmental ductal polypoid lesions and mild intrahepatic ductal dilatation. Resection of this premalignant, multifocal disease is often impossible. (Courtesy S. Yeon Kim, MD.) (Right) Coronal CT reconstruction of the same patient again shows filling defects within the common duct . Bile duct resection confirmed multiple papillary neoplasms associated with invasive carcinoma. (Courtesy S. Yeon Kim, MD.)

965

Biliary System

Biliary IPMN KEY FACTS

TERMINOLOGY

PATHOLOGY

• Mucin-producing papillary neoplasm arising from biliary mucosa

• Unknown etiology, but associations with hepatolithiasis and Clonorchis suggest chronic biliary inflammation may be causative

IMAGING • ERCP: Extrusion of clear mucin from patulous ampulla visible to endoscopist due to tumor mucin hypersecretion ○ Massively dilated bile ducts (either diffuse or localized) filled with mucin ○ Mural nodules best visualized after removal of mucin ○ Biliary dilation both proximal and distal to mural nodule • CT/MR: Markedly dilated intra-/extrahepatic bile ducts with mural nodularity or discrete intraductal mass ○ Attenuation and MR signal characteristics of mucin distending ducts is similar to normal bile ○ Presence of mural nodularity or soft tissue suggests presence of malignancy

(Left) Graphic of biliary intrapapillary mucinous tumor demonstrates the segmental distension of the right lobe intrahepatic ducts , which are filled with mucin and contain a mucosal mass arising from the ductal epithelium. (Right) Axial T1WI MR with gadolinium in a woman with midepigastric pain and elevated alkaline phosphatase shows fusiform dilatation of the left bile ducts , which proved to be biliary IPMN at surgery.

(Left) Axial CECT in a patient presenting with RUQ pain and elevated alkaline phosphatase demonstrates atrophy of the left lobe and marked dilation of the left bile duct greater than the right. ERCP and subsequent surgery revealed a left duct biliary IPMN. (Right) Axial CECT shows asymmetric left biliary ductal dilatation and subtle enhancing nodularity within the proximal left duct . Intraductal cholangiocarcinoma and background biliary IPMN were identified at histology. (Courtesy S. Yeon Kim, MD.)

966

CLINICAL ISSUES • Most common in elderly patients from East Asia • May present with repeated episodes of cholangitis and jaundice • Biliary IPMN localized to intrahepatic ducts may be treated with partial hepatectomy if tumor is relatively localized • Resection of the common duct with Roux-en-Y anastomosis may be required for tumors involving either extrahepatic duct or right/left main ducts • Stenting or drainage to alleviate jaundice in patients who are not surgical candidates • Multifocality frequent, and recurrences after surgery are common due to small foci of undetected disease in biliary tree distant from site of resection

Biliary IPMN

Definitions

Ultrasonographic Findings

• Mucin-producing papillary neoplasm arising from biliary mucosa ○ Only recently added to WHO classification in 2010 ○ Significant overlap with biliary papillomatosis, and some authors suggest they are same entity

• Grayscale ultrasound ○ Complex "mass" of aneurysmally dilated bile ducts ○ Echogenic intraductal masses juxtaposed against anechoic mucin filling duct ○ Linear echoes within dilated ducts may suggest mucobilia (layer sign)

Abbreviations • Intraductal papillary mucinous neoplasm (IPMN) of bile ducts

Synonyms

IMAGING General Features • Best diagnostic clue ○ Diffuse segmental "aneurysmal" dilation of bile ducts with a polypoid or nodular intraductal mass ○ Biliary dilation both proximal and distal to mural nodule due to mucin hypersecretion • Location ○ Intra-/extrahepatic bile ducts: Most common locations are left liver lobe ducts and liver hilum • Morphology ○ "Aneurysmal," marked dilatation of mucin-distended ducts

Radiographic Findings • ERCP ○ Extrusion of clear mucin from patulous ampulla visible to endoscopist due to mucin hypersecretion by tumor ○ Massively dilated bile ducts (either diffuse or localized) filled with mucin – Mucin-filled bile ducts may result in nonvisualization of affected segment(s) due to difficulty of filling mucinfilled ducts with contrast – Amorphous filling defects in dilated ducts may representing either mucin plugs or tumor ○ Mural nodules best visualized after removal of mucin

CT Findings • Markedly dilated intra-/extrahepatic bile ducts with mural nodularity or discrete intraluminal papillary/fungating mass ○ Attenuation of mucin distending ducts is similar to normal bile – Mucin within ducts cannot be differentiated from normal bile on CT ○ Presence of mural nodularity or soft tissue component should suggest presence of malignancy

MR Findings • Diffuse or segmental biliary ductal dilatation with bile duct contents appearing hyperintense on T2WI and hypointense on T1WI (similar to normal bile) ○ Mucin within ducts cannot be differentiated from normal bile on MR

Biliary System

• Intraductal papillary neoplasm of liver, mucin-secreting biliary papillomatosis, mucin-producing cholangiocarcinoma, mucinous ductal ectasia of biliary tree

○ ERCP/MRCP mismatch: Mucin-filled duct is not visible on ERCP while it is seen on MRCP ○ Hepatobiliary contrast agents (i.e., Eovist) may demonstrate nonfilling of affected ducts (i.e., those filled with mucin), similar to ERCP • Papillary projections or discrete soft tissue masses within dilated ducts appear hypointense on T1WI, hyperintense on T2WI, and enhancing on T1WI C+ ○ Enhancing mural nodularity raises concern for malignancy

TERMINOLOGY

Nuclear Medicine Findings • PET/CT ○ Malignant biliary IPMN has increased FDG avidity

Imaging Recommendations • Best imaging tool ○ CECT, MRCP

DIFFERENTIAL DIAGNOSIS Biliary Cystadenoma/Cystadenocarcinoma • Primary cystic liver mass (typically multilocular) with internal septations, mural nodularity, and calcifications • No communication with bile ducts: Any mucin produced by tumor is confined to mass itself • Most common in middle-aged women

Cholangiocarcinoma • Conventional cholangiocarcinoma manifests as infiltrative or nodular mass arising from biliary tree with biliary stricture, but without mucin production • Malignant biliary IPMN is a rare form of peripheral cholangiocarcinoma (papillary form) characterized by intraductal growth ○ Constitutes 3-9% of cholangiocarcinomas with more favorable prognosis compared to more common massforming or periductal infiltrating cholangiocarcinoma • Often will demonstrate delayed enhancement on multiphase imaging

Recurrent Pyogenic Cholangitis • Disease characterized by cast-like pigment stones throughout biliary tree, biliary strictures resulting in intraand extrahepatic biliary dilatation, and repeated bouts of cholangitis • Most common in patients living in or from Southeast Asia • Filling defects within biliary tree represent stones (not mucin or tumor as with biliary IPMN)

Pyogenic Liver Abscess • Multiloculated cystic mass in liver with a thick, enhancing wall and surrounding liver parenchymal edema • No dilated bile ducts, mucin production, or intraductal mass • Clinical history of fever and sepsis 967

Biliary System

Biliary IPMN

Bacterial Cholangitis • Typically secondary to biliary obstruction (most often due to choledocholithiasis) • Bile duct walls appear thickened and hyperenhancing with heterogeneous liver parenchymal perfusion (particularly on arterial phase imaging) • Infectious debris or pus within dilated bile ducts may mimic the presence of intraductal mucin or tumor

PATHOLOGY General Features • Etiology ○ Unknown, but strong associations with hepatolithiasis and Clonorchis, suggesting chronic biliary inflammation may be a causative factor • Genetics ○ No known genetic disposition • Associated abnormalities ○ Cases in East Asia strongly associated with biliary stones (especially hepatolithiasis) and Clonorchis infection

Demographics • Age ○ 5th through 7th decades • Gender ○ No clear gender predilection • Ethnicity ○ Most common in patients from East Asia

Staging, Grading, & Classification

Natural History & Prognosis

• Types (based on morphology) ○ Ductectatic type: Tumor in diffusely dilated bile duct ○ Cystic type: Large cystic lesion communicating with bile duct ○ Intermediate type: Cystic lesion communicating with bile duct + solid tumor ○ Analogous to classification of pancreatic IPMN into main branch, side branch, and mixed subtypes • Types (based on imaging appearance) ○ Type I: Diffuse ductal dilatation with visible intraductal mass ○ Type II: Diffuse ductal dilatation without visible intraductal mass ○ Type III: Intraductal papillary mass with localized ductal dilatation ○ Type IV: Mild ductal dilatation with intraductal cast-like lesions (either mucin plugs or tumor) ○ Type V: Focal stricture-like lesion with mild proximal biliary dilatation

• Repeated episodes of cholangitis and jaundice (due to biliary obstruction by the mass, tumor emboli, or mucin) • Good prognosis for adenomas or dysplasia; invasive cancer prognosis depends on nodal status ○ Invasive papillary cholangiocarcinoma has an overall better prognosis than more common mass-forming and periductal infiltrating cholangiocarcinoma subtypes • High rates of recurrence (20% at 5 years for benign IPMNs and 60% at 5 years for malignant IPMNs) ○ Multifocality frequent, and recurrences likely due to small foci of undetected disease in biliary tree distant from site of resection

Gross Pathologic & Surgical Features • Markedly distended, mucin-filled bile ducts with frond-like papilloma

Microscopic Features • Counterpart of pancreatic IPMN ○ Often associated with mucin hypersecretion ○ Strong tendency for multifocal disease (papillomatosis) • Spectrum: Adenomatous dysplasia to frank invasive adenocarcinoma; usually coexist • Premalignant lesion with high potential for malignancy: Adenoma to carcinoma sequence • Likely a precursor to intraductal papillary cholangiocarcinoma

CLINICAL ISSUES Presentation • Most common signs/symptoms 968

○ Most common presentation is repeated bouts of acute cholangitis: Abdominal pain, fever, chills, jaundice – Biliary obstruction due to tumor, mucin production, or detached tumor fragments – Intermittent biliary obstruction may mimic symptoms of biliary calculi or recurrent pyogenic cholangitis • Other signs/symptoms ○ CEA common: More likely to be in patients with malignant biliary IPMN or large mucin secretion ○ Other laboratory markers may be elevated due to biliary obstruction: ALT/AST, bilirubin, GGT • Clinical profile ○ Asian patient with recurrent abdominal pain and fever

Treatment • Biliary IPMN localized to intrahepatic ducts may be treated with partial hepatectomy if tumor is relatively localized • Resection of the common duct with Roux-en-Y anastomosis may be required for tumors involved either extrahepatic duct or right/left main ducts • Patients who are not surgical candidates due to extent of disease treated palliatively with stenting or drainage to alleviate jaundice

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Consider biliary IPMN in patients with aneurysmal dilation of biliary tree (often in a segmental or lobar distribution) with nodular enhancing intraductal tumor

SELECTED REFERENCES 1. 2.

Bal MM et al: Intraductal papillary neoplasm of the bile duct: a rarity. Indian J Pathol Microbiol. 57(1):144-5, 2014 Ohtsuka M et al: Intraductal papillary neoplasms of the bile duct. Int J Hepatol. 2014:459091, 2014

Biliary IPMN Biliary System

(Left) ERCP in a patient with RUQ pain and elevated bilirubin demonstrates a grossly dilated common bile duct filled with amorphous mucin , found to be a biliary IPMN. (Right) Axial CECT shows a multiloculated cystic liver mass with an irregular wall and contiguity with the biliary tree. Note the dilated common duct , which communicates with the mass. This was found to be malignant degeneration of a biliary IPMN, with much of the "mass" representing dilated intrahepatic ducts filled with mucin.

(Left) ERCP of a patient with jaundice shows amorphous linear filling defect within a dilated common duct. CECT (not shown) revealed marked asymmetric right and common bile duct dilatation. (Courtesy S. Yeon Kim, MD.) (Right) Endoscopic image of the duodenum in the same patient shows green mucin draining from a patulous, bulging papilla. The final diagnosis after right hepatectomy and bile duct resection was biliary IPMN associated with invasive carcinoma. (Courtesy S. Yeon Kim, MD.)

(Left) Axial CECT of a 75-yearold man shows mild left intrahepatic biliary ductal dilatation . An ERCP performed previously reported a mucus "plug." (Right) Axial CECT of the same patient performed 6 years later shows marked left biliary ductal dilatation , lobar atrophy, and calcifications . Biliary IPMN and mucinous adenocarcinoma were identified at left hepatectomy. Biliary IPMN is a premalignant lesion and is considered a precursor for papillary cholangiocarcinoma.

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SECTION 11

Pancreas

Introduction and Overview Imaging Approach to the Pancreas

972

Congenital Agenesis of Dorsal Pancreas Annular Pancreas Pancreas Divisum Asymmetric Fatty Lobulation of the Pancreas Ectopic Pancreatic Tissue

980 981 982 986 988

,QƮDPPDWLRQ Acute Pancreatitis and Complications Chronic Pancreatitis Groove Pancreatitis Autoimmune (IgG4) Pancreatitis

990 1000 1004 1008

Degenerative Pancreatic Lipomatous Pseudohypertrophy

1012

Trauma Pancreatic Trauma

1014

Treatment Related Postoperative Pancreas Pancreatic Transplantation

1018 1022

Benign Neoplasms and Tumor-Like Conditions Pancreatic Serous Cystadenoma Nonneoplastic Pancreatic Cysts

1026 1030

Malignant Neoplasms Pancreatic Ductal Carcinoma Mucinous Cystic Pancreatic Tumor Pancreatic IPMN Pancreatic Neuroendocrine Tumors Pancreatic Solid and Pseudopapillary Neoplasm Pancreatic Metastases and Lymphoma Atypical and Rare Pancreatic Tumors

1034 1042 1048 1054 1060 1064 1068

Pancreas

Imaging Approach to the Pancreas

Embryology and Normal Variants The body-tail segment of the pancreas develops from the embryologic dorsal pancreatic bud, while the head-uncinate segments develop from the ventral bud, which also gives rise to the liver and biliary tree. During normal development, the ventral bud migrates clockwise around the fetal duodenum and eventually merges with the dorsal bud to form the pancreas, with the branching pancreatic and biliary ducts in communication. Variations in this process are relatively common, including many variations of the pancreatic duct branching pattern. Among the most common is pancreas divisum, in which there is little or no communication between the accessory duct of Santorini and the main duct of Wirsung that drains the pancreatic head. Errors of rotation and fusion may also result in a completely circumferential or annular pancreas, which may be associated with pancreatitis as well as obstruction of the duodenal lumen. As a result of their separate embryologic origins, the ventral and dorsal pancreatic segments may exhibit varying morphology, ranging from variations in the degree of fatty lobulation to complete absence of the dorsal pancreas. Both may simulate serious pathology unless one is familiar with these normal variants. Pancreatic size and the degree of fatty lobulation vary substantially within the population based on patient age, body habitus, and other factors. In patients over the age of 70, the parenchyma atrophies, often develops small foci of calcification, and the pancreatic duct dilates slightly. These signs should not be interpreted as evidence of chronic pancreatitis without corroborating clinical evidence.

Imaging Protocols Ultrasound may be the first study performed in the evaluation of abdominal pain. The pancreas, however, is often incompletely evaluated secondary to overlying bowel gas. If a cystic mass is identified, color Doppler should always be performed to rule out a vascular lesion. For most lesions, the pancreas is far better evaluated with CT and MR using multiphasic and multiplanar imaging. Most ductal carcinomas are best detected as hypoenhancing masses relative to the normal pancreas, while endocrine (islet cell) tumors are hypervascular. Both types of tumors may be evident only on the arterial or pancreatic parenchymal phase of imaging (about 35-45 second delay). Hepatic metastases from endocrine tumors may also be evident only on arterial phase images. Portal venous (hepatic parenchymal) phase images remain necessary in order to evaluate hypovascular metastases, venous involvement, and other anatomic features. CT protocol: Obtaining a series of noncontrast scans through the liver and pancreas helps in recognition of small foci of calcification and degree of tumor enhancement, and helps in localization for subsequent series. Since some hypervascular tumors (e.g., gastrinoma) may arise in the wall of the duodenum, and because multiplanar CT angiography is so often a useful adjunct, it is best to give only water or a neutral oral contrast agent rather than barium or iodinated contrast that may obscure intramural lesions or make CT angiography difficult. 972

Arterial (pancreatic parenchymal) phase images should be obtained through the liver and pancreas as contiguous 0.65 to 1.25 mm images, reconstructed for viewing at 2.5 to 5 mm thick sections. The thinner source images are required for optimal multiplanar reformations. Portal venous (hepatic parenchymal) phase images should be obtained through the liver and pancreas as well, using the same parameters. Multiplanar reformations are very useful in recognizing and characterizing pancreatic disease. Curved planar reformations along the pancreatic duct offer the most compelling evidence of abrupt narrowing by a tumor mass or chronic pancreatitis. Variations of coronal and sagittal planes frequently make peripancreatic nodal involvement and local invasion more evident, and may even be essential in recognizing a lesion as being intra- or peripancreatic in origin (e.g., an accessory spleen vs. an islet cell tumor in the tail of the pancreas). MR protocols: There are many vendor-specific pancreatic protocols, but the basic examination should include gradientecho T1-weighted imaging in- and out-of-phase, T2-weighted images, and dynamic gadolinium-enhanced gradient-echo images with fat suppression. An MRCP should be performed in cases of suspected pancreatic pathology to evaluate both the pancreatic and biliary ducts.

Approach to the Abnormal Pancreas Unlike other abdominal organs, the pancreas has only a thin capsule that is easily broached by inflammatory and neoplastic processes. Processes that originate within the pancreas can easily spread to adjacent structures, including other viscera within the anterior pararenal space, such as the duodenum and vertical colon segments. Pancreatitis, for instance, often affects the duodenal lumen and may cause inflammation of the descending colon as well. Pancreatic malignancies commonly invade the adjacent viscera, and even more commonly adjacent vessels and nerves, largely accounting for their poor prognosis. Invasion into the lumen of the splenic vein, which runs within the pancreas, leads to liver metastases, while occlusion of the splenic vein leads to characteristic perigastric varices in the absence of esophageal varices or cirrhosis. This may constitute the most obvious sign on imaging of a small primary tumor. Obstruction or dilation of the pancreatic &/or common bile duct (CBD) is another indirect but useful sign of pancreatic disease. Pancreatic ductal dilation is most frequently due to ductal carcinoma or chronic pancreatitis, but may also result from intraductal papillary mucinous neoplasm (IPMN), neuroendocrine tumor, or even metastases to the pancreas. Obstruction of the intrapancreatic bile duct may result from the same inflammatory and neoplastic processes of the pancreas. Obstruction of only the distal CBD with a normal pancreatic duct is more likely the result of primary inflammatory, infectious, neoplastic, or calculous disease originating in the biliary system. Pancreatic ductal carcinomas are hypovascular tumors, and often present on imaging as hypodense (hypointense) masses with abrupt obstruction of the ducts. Metastases to the pancreas from primary tumors such as lung, breast, or melanoma may simulate a primary ductal cancer. Neuroendocrine tumors are more often hypervascular and may be simulated by metastases from hypervascular primary tumors, such as renal cell carcinoma.

Imaging Approach to the Pancreas

Aneurysmal dilation of a peripancreatic artery (or varix) should be considered in the differential diagnosis of any cystic pancreatic mass. The presence of flowing blood must be determined by rapid IV administration of contrast medium for CT or MR, or by color Doppler sonography. Pancreatitis and complications of pancreatitis are commonly encountered in abdominal imaging. Because the pancreas is separated from the lesser sac by only the posterior parietal peritoneum, acute pancreatitis often results in exudation of fluid into the lesser sac, which should not be mistaken for a pseudocyst. These fluid collections usually resolve quickly, while pseudocysts take longer to resolve, and have, by definition, a fibroinflammatory wall. The tail of the pancreas is the distal few centimeters of the gland that lies within the splenorenal ligament and is actually intraperitoneal. Acute inflammation of the pancreatic tail may result in an intrasplenic pseudocyst and pancreatic ascites. Tumors arising from the pancreatic tail can easily invade the spleen without crossing an anatomic boundary. An important potential pitfall in this area is the accessory spleen, which may be located within the tail and mimic a hypervascular pancreatic mass.

Differential Diagnosis Hypovascular Pancreatic Mass Common • Pancreatic ductal carcinoma • Chronic pancreatitis • Mucinous cystic pancreatic tumor • Normal variants, pancreas (mimic) • Peripancreatic lymphadenopathy • Unopacified bowel (mimic) • Duodenal diverticulum (mimic) Less Common • Serous cystadenoma, pancreas • Ampullary carcinoma • Pancreatic metastases and lymphoma • Cholangiocarcinoma • Pancreatic islet cell tumors • Solid and papillary neoplasm • Acute pancreatitis • Autoimmune (IgG4-related) pancreatitis • Groove pancreatitis • Gastric tumors (mimic) • Agenesis of dorsal pancreas • Adrenal mass (mimic) • Adjacent masses (mimic)

Rare but Important • Atypical and rare pancreatic tumors Hypervascular Pancreatic Mass Common • Pancreatic neuroendocrine (islet cell) tumors

Pancreas

Cystic pancreatic masses are discovered frequently on CT, MR, or ultrasound, making a pragmatic approach to their evaluation mandatory. Clinical history is necessary, as is consideration of the age, gender, and presence of laboratory evidence of pancreatitis. For example, mucinous cystic neoplasms occur almost exclusively in young or middle-aged women, while solid and papillary neoplasms occur in girls and young women. Pseudocysts are often indistinguishable from cystic tumors by imaging alone, but usually occur in patients with known pancreatitis and evolve in size much more rapidly than tumors. Certain cystic tumors may have a characteristic appearance, allowing confident diagnosis and management; others will require further evaluation, with endoscopic US emerging as the single most accurate means of guiding diagnosis and management in more complex cases.

Less Common • Pancreatic metastases • Serous cystadenoma, pancreas • Accessory spleen (mimic) • Vascular lesions, peripancreatic • Pheochromocytoma (mimic) • Renal cell carcinoma (mimic) • Gastric stromal tumor (mimic) • Carcinoid tumor (mimic) • Splenic tumors (mimic) Cystic Pancreatic Mass Common • Pancreatic pseudocyst • Lesser sac ascites (mimic) • Mucinous cystic pancreatic tumor • IPMN, pancreas • Pancreatic ductal carcinoma (necrotic) • Duodenal diverticulum (mimic) Less Common • AD polycystic disease, kidney • Cystic fibrosis, pancreas • Von Hippel-Lindau disease • Serous cystadenoma, pancreas • Solid and papillary epithelial neoplasm (SPEN) • Pancreatic islet cell tumors • Epithelial (true) cyst, pancreas • Pseudoaneurysm (mimic) • Portal vein aneurysm (mimic) • Metastases and lymphoma, pancreas • Gastric stromal tumor (mimic) • Choledochal cyst (mimic) • Lymphangioma, peripancreatic • Pancreatic abscess Rare but Important • Hydatid cyst • Teratoma, retroperitoneum • Anaplastic carcinoma, pancreas • Duplication cyst, duodenum Atrophy or Fatty Replacement of Pancreas Common • Chronic pancreatitis • Senescent change • Obesity • Diabetes mellitus • Cystic fibrosis, pancreas • Steroid medication Less Common • Cushing syndrome • Variant, asymmetric fatty infiltration • Lipomatous pseudohypertrophy • Shwachman-Diamond syndrome • Agenesis of dorsal pancreas Dilated Pancreatic Duct Common • Pancreatic ductal carcinoma • Chronic pancreatitis 973

Pancreas

Imaging Approach to the Pancreas

• Senescent change, pancreas • IPMN, pancreas Less Common • Ampullary carcinoma • Duodenal carcinoma • Choledocholithiasis Infiltration of Peripancreatic Fat Planes Common • Acute pancreatitis • Pancreatic ductal carcinoma • Anasarca • Portal hypertension, varices • Traumatic pancreatitis • Duodenal or gastric ulcer Less Common • Shock pancreas • Sclerosing mesenteritis • Autoimmune (IgG4-related) pancreatitis • Groove pancreatitis • Duodenal diverticulitis

(Left) Graphic shows the ventral pancreatic anlagen developing as an outpouching of the hepatic-biliary diverticulum. As the stomach and duodenum elongate, the ventral pancreas and bile ducts rotate clockwise and posteriorly to fuse with the dorsal pancreas. (Right) ERCP of pancreatic divisum shows that the main and accessory pancreatic ducts do not communicate. This results embryologically from failure of fusion of the ducts between the dorsal and ventral pancreatic anlagen.

(Left) Axial CECT shows normal senescent changes within the pancreas . The top image (A) is from a 30year-old woman and the bottom image (B) is from a 78year-old man. With aging, the pancreas decreases in size with increased fatty lobulation. Small calcifications and mild ductal dilatation may also be seen. (Right) Coronal reformatted CECT shows the relationship of the pancreatic head to the 2nd portion of the duodenum .

974

Pancreatic Calcifications Common • Chronic pancreatitis • Pancreatic pseudocyst • Senescent change, pancreas • Vascular lesions, peripancreatic • Choledocholithiasis (mimic) • Duodenal diverticulum (mimic) Less Common • Mucinous cystic pancreatic tumor • Cystic fibrosis, pancreas • Pancreatic islet cell tumors • Serous cystadenoma, pancreas • Solid and papillary epithelial neoplasm (SPEN) • IPMN, pancreas • Hereditary pancreatitis

Imaging Approach to the Pancreas Pancreas

(Left) In this elderly man with painless jaundice, axial CECT shows a hypodense mass in the head of the pancreas and a distended gallbladder . (Right) Coronal CT reformation in the same case shows the dilated pancreatic duct interrupted as it enters the hypodense mass , a typical presentation of pancreatic ductal carcinoma.

(Left) This 35-year-old man presented with jaundice and weight loss, with axial CECT showing a hypodense mass in the head of the pancreas causing biliary obstruction and dilation of the gallbladder . (Right) Curved planar reformation of CECT in the same case shows the pancreatic "mass" causing partial obstruction of the bile duct , while the pancreatic duct is only mildly dilated. Further evaluation, including biopsy, confirmed a diagnosis of autoimmune (IgG4-related) pancreatitis.

(Left) In this 81-year-old man with painless jaundice, a curved planar reformatted CECT shows dilation of the common bile duct and pancreatic duct due to a small hypodense ampullary carcinoma . (Right) Coronal 3D reformatted CT in the same case clearly shows the dilated bile duct , pancreatic duct , and ampullary tumor .

975

Pancreas

Imaging Approach to the Pancreas

(Left) In this 63-year-old man with intractable peptic ulcers, axial CECT shows a thickwalled, hyperemic stomach . (Right) Arterial phase CT in the same case shows a subcentimeter mass in the pancreatic head that proved to be a gastrinoma (1 type of pancreatic endocrine tumor) that was responsible for this patient's Zollinger-Ellison syndrome.

(Left) In this elderly man, axial CECT shows a bulky, hypervascular mass originating from the pancreas with direct invasion of the splenic vein , typical features of a malignant neuroendocrine tumor. (Right) In this 62-year-old woman with pancreatic metastasis from renal cancer (resected 10 years prior), axial CECT shows surgical absence of the left kidney but no evidence of recurrence in the surgical bed. There is a hypervascular mass with parenchymal atrophy and pancreatic ductal dilation upstream .

(Left) In this 50-year-old man who had a multivisceral organ transplantation, axial CECT shows a pseudoaneurysm of the arterial graft anastomosis that simulates a hypervascular pancreatic mass. (Right) In this 52-yearold man with cirrhosis and portal vein thrombosis, axial CECT shows a mass of varices in and around the pancreatic head that might be mistaken for a hypervascular tumor of the pancreas.

976

Imaging Approach to the Pancreas Pancreas

(Left) In this 45-year-old man, axial T2WI MR shows a retrogastric pseudocyst that displaces the stomach . (Right) Axial NECT scan in the same case taken 2 weeks later shows spontaneous resolution of the pseudocyst, which has emptied into the stomach through a visible tract . The patient's clinical symptoms improved at the same time. Pseudocysts, unlike cystic pancreatic neoplasms, usually evolve in size quickly, which may aid in distinction.

(Left) In this 33-year-old woman, axial CECT shows an encapsulated cystic mass within the body-tail of the pancreas. Note the septa dividing it into several noncommunicating cystic spaces, a classic presentation for mucinous cystic neoplasm. (Right) In this 57-year-old woman, CT shows an encapsulated cystic pancreatic mass that displaces, but does not involve, the pancreatic duct . The mass has a "honeycomb" or "sponge" appearance, characteristic of serous microcystic adenoma.

(Left) In this 21-year-old woman, axial CECT shows a complex cystic mass in the tail of the pancreas, with peripheral rim calcification and solid mural nodularity , typical features of a solid and papillary epithelial neoplasm (SPEN) of the pancreas. (Right) In this 71-year-old woman, coronal reformatted CT shows a mixed solid and cystic pancreatic mass that proved to be a neuroendocrine tumor.

977

Pancreas

Imaging Approach to the Pancreas

(Left) In this 44-year-old man with von-Hippel Lindau disease, axial CECT shows a cluster of benign cysts in the pancreatic body and tail as well as simple cysts in both kidneys . (Right) Another CT section in the same case shows one of several solid enhancing renal masses , representing renal cell carcinoma.

(Left) In this 62-year-old man, axial CECT shows a multiseptate mass that abuts the pancreas, duodenum, and portal vein . The mass is not in the pancreas but is peripancreatic and is a lymphangioma. (Right) In this woman with cirrhosis, axial CECT shows an "eggshell" calcification in or near the pancreas that might be mistaken for a cystic pancreatic neoplasm. This represents an aneurysmally dilated and thrombosed portal vein varix in a patient with severe cirrhosis and portal hypertension.

(Left) In this elderly woman with pain and steatorrhea, axial CECT shows massive dilation of the pancreatic duct throughout its length with cystic "masses" in communication with the main and side branches . (Right) MRCP in the same case confirms the dilation of the main duct as well as the side branches . This appearance could be due to chronic pancreatitis, but main and side-branch IPMN was confirmed on endoscopic sonography.

978

Imaging Approach to the Pancreas Pancreas

(Left) In this middle-aged alcoholic man, axial CECT shows dilation of the intrahepatic bile ducts . (Right) A more caudal CT section in the same case shows marked atrophy of the pancreatic parenchyma and dilation of the pancreatic duct , with extensive calcifications within the ducts and parenchyma. No soft tissue mass was seen and all findings were attributed to chronic pancreatitis.

(Left) Coronal curved planar CT reformation shows a sharp transition from normal to abnormal pancreatic duct caused by a small, subtle pancreatic ductal cancer. Multiplanar imaging greatly enhances the ability to evaluate pancreatic masses. (Right) In this 73-year-old man, a curved planar CT shows dilation of the main pancreatic duct within the body-tail segment, tapering gradually to a normal caliber duct in the neck. ERCP with sampling of the mucinous pancreatic duct contents confirmed main duct IPMN.

(Left) In this 88-year-old woman with no clinical signs of chronic pancreatitis, axial CECT shows multiple focal calcifications within the pancreas that are separate from vascular calcifications. There is no pancreatic ductal dilation and these are considered normal senescent changes. (Right) Another CT section in the same case shows additional pancreatic calcification that is somewhat larger than usually seen in senescent change of the pancreas, but the patient remained symptom-free.

979

Pancreas

Agenesis of Dorsal Pancreas KEY FACTS

• Rare congenital anomaly resulting in either complete or partial failure of development of dorsal pancreas

IMAGING • CT and MR findings ○ Complete agenesis: Complete absence of pancreatic neck, body, and tail, Santorini duct, and minor papilla – Ventral pancreas (head and uncinate) appears normal – MRCP: Visualization only of short ventral duct, with absence of accessory and dorsal duct system ○ Partial agenesis: Variable appearance of pancreatic body (depending on degree of agenesis), with small remnant Santorini duct and minor papilla – Pancreas may appear short or truncated with normal pancreatic head and rounded upstream margin • ERCP ○ Complete agenesis: Filling of short ventral duct without identifiable dorsal ducts or minor papilla

(Left) Axial CECT shows a normal-appearing pancreatic head , but neither body nor tail are present. This patient has congenital absence of the dorsal pancreas and has had at least 1 episode of acute pancreatitis. (Right) ERCP shows filling of the ventral pancreatic duct within the head and uncinate process only, without filling of the ducts in the pancreatic body or tail, characteristic of agenesis of the dorsal pancreas. Note the normal tapering of the pancreatic duct and its side branches.

(Left) Axial CECT shows no pancreatic tissue or duct in the expected position of the bodytail segments. There should normally be pancreatic tissue along the anterior aspect of the splenic vein . (Right) Axial CECT in a patient with polysplenia syndrome demonstrates partial agenesis of the dorsal pancreas. There is still a hypoplastic pancreatic body, which demonstrates a characteristic rounded margin , as well as complete absence of the pancreatic tail. Agenesis of the dorsal pancreas is associated with polysplenia.

980

○ Partial agenesis: Main pancreatic duct is shortened, some dorsal ducts remain with filling of atretic Santorini duct

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES • • • • •

Pancreatic ductal carcinoma Chronic pancreatitis (pseudoagenesis) Pancreatic divisum Pancreatic lipomatosis Post-traumatic pancreatic atrophy

PATHOLOGY • Embryologic dorsal bud forms pancreatic body, tail, superior head, Santorini duct, and minor papilla • Agenesis of dorsal pancreas due to defect of dorsal bud • Associated with polysplenia/heterotaxy syndrome and bowel malrotation

CLINICAL ISSUES • Usually asymptomatic, but is associated with increased incidence of pancreatitis and diabetes

Annular Pancreas

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Congenital anomaly resulting in pancreatic tissue partially or completely encircling descending duodenum

• • • •

IMAGING • CT: Enlarged pancreatic head encircling 2nd portion of duodenum ○ Incomplete annular pancreas: Pancreatic tissue may extend anterolateral or posterolateral to duodenum or anterior and posterior to duodenum ("crocodile-jaw" configuration) • MR: Normal pancreatic tissue (with identical signal to normal pancreas) encircling duodenum ○ MRCP: Main pancreatic duct encircling duodenum (and abnormally extending to right side of duodenum) ○ Secretin dilates duct and facilitates diagnosis • Fluoroscopic barium study (upper GI): Extrinsic smooth compression and narrowing of 2nd part of duodenum

Duodenal carcinoma Pancreatic ductal carcinoma Postbulbar peptic ulcer Multiple other causes of duodenal stenosis

Pancreas

KEY FACTS

PATHOLOGY • Etiology: Incomplete rotation of ventral anlage leads to pancreatic tissue encircling 2nd part of duodenum ○ Other congenital anomalies in up to 75% of pediatric cases (Down syndrome, duodenal atresia, etc.)

CLINICAL ISSUES • 50% of cases present in infancy due to gastric outlet obstruction • Most adults asymptomatic, but rare symptoms include gastric obstruction, upper GI bleeding, and jaundice • Associated in adults with gastric/duodenal ulcers and pancreatitis; questionable link with pancreatic cancer

(Left) Graphic shows concentric luminal narrowing of the 2nd portion of the duodenum by encircling annular pancreatic tissue. The pancreatic head duct also encircles the descending duodenum. Note the proximal duodenal dilatation . (Right) ERCP shows a small pancreatic head duct originating on the right anterior surface of the duodenum, encircling it, and emptying into the main pancreatic duct near the ampulla .

(Left) Axial CECT demonstrates pancreatic tissue completely encircling the duodenum . Notice the different enhancement of the pancreatic tissue and the duodenal wall. (Right) Sagittal CECT in the same patient demonstrates that the duodenum is narrowed by pancreatic tissue both anteriorly and posteriorly. While adults with annular pancreas are usually asymptomatic, this patient was experiencing intermittent obstruction and early satiety.

981

Pancreas

Pancreas Divisum KEY FACTS

TERMINOLOGY • Anatomic variant of pancreatic ductal anatomy resulting from failure of ventral and dorsal pancreatic buds to fuse

IMAGING • Normal anatomy ○ Head and uncinate process of pancreas drained by ventral pancreatic duct of Wirsung via major papilla ○ Body and tail of pancreas drained by dorsal pancreatic duct of Santorini via minor papilla • MRCP: Best noninvasive modality for delineating divisum ○ Dominant dorsal duct, which appears long and narrow, directly entering minor papilla – Main pancreatic duct may be mildly dilated ○ Ventral duct appears short and drains into major papilla ○ No communication between dorsal and ventral ducts ○ Secretin-enhanced MR/MRCP may help better delineate divisum by distending pancreatic duct • ERCP: Most accurate method of diagnosing divisum

(Left) Graphic shows several common variations in the arrangement of the main pancreatic duct , the accessory duct of Santorini , and the duct of Wirsung . The lower right image shows pancreas divisum. (Right) ERCP image after cannulation of the major papilla demonstrates filling of only a short ventral duct and its side branches. There is no communication with the dorsal duct, compatible with pancreatic divisum.

(Left) ERCP in a patient with pancreas divisum and chronic pancreatitis shows dilatation and irregularity of the dorsal pancreatic duct and small pseudocysts following cannulation of the minor papilla. (Right) Coronal MRCP shows the dorsal pancreatic duct crossing the common bile duct to drain into the expected location of the minor papilla . The ventral duct is not seen. Note the dilatation of multiple tiny pancreatic duct sidebranches throughout the gland, likely reflecting the patient's history of chronic pancreatitis.

982

○ Cannulation of major papilla reveals opacification of short, tapered, ventral pancreatic (Wirsung) duct – Contrast does not flow past pancreatic head ○ Cannulation of minor papilla reveals opacification of long (and sometimes dilated) dorsal pancreatic (Santorini) duct which drains nearly entire pancreas ○ No communication between dorsal and ventral ducts • CT: May demonstrate abnormally large pancreatic head or 2 distinct pancreatic moieties separated by fat cleft

CLINICAL ISSUES • Most common congenital anatomic variant of pancreas • May be associated with recurrent pancreatitis (mostly in children), although less than 5% are symptomatic ○ Poor drainage from body and tail (due to relative stenosis at minor papilla) leads to pancreatitis • Incidental finding in asymptomatic patient: No treatment • Severely symptomatic patients: Surgical sphincteroplasty or endoscopic papillotomy of minor papilla

Pancreas Divisum

Definitions • Anatomic variant of pancreatic ductal anatomy resulting from failure of ventral and dorsal pancreatic buds to fuse

IMAGING

○ No communication between ventral and dorsal ducts • Changes in pancreatic morphology may also suggest divisum, but frequency of findings is low ○ Abnormal contour of pancreatic head and neck with large pancreatic head ○ 2 distinct pancreatic moieties separated by fat cleft • Acute or chronic pancreatitis may be present

General Features

Radiographic Findings

• Best diagnostic clue ○ Normal branching pattern of short ventral duct with no communication between ventral duct and long dorsal duct on ERCP • Normal PD anatomy ○ Head and uncinate process of pancreas drained by ventral pancreatic duct (PD) of Wirsung via major papilla ○ Body and tail of pancreas drained by dorsal PD of Santorini via minor papilla

• ERCP: Most accurate method of diagnosing divisum, but carries risks of invasive procedure ○ Cannulation of major papilla reveals opacification of short, tapered, ventral pancreatic duct – Contrast injected into major papilla does not flow past pancreatic head – Ventral duct maintains normal branching pattern, unlike truncated, abrupt cut-off of ventral duct in pancreatic cancer ○ Cannulation of minor or accessory papilla reveals opacification of long (and sometimes dilated) dorsal pancreatic duct that drains nearly entire pancreas except posterior head and uncinate – Cannulation of minor papilla may be technically difficult due to small size ○ No communication between dorsal (long) and ventral (short) PDs

MR Findings • MRCP is best noninvasive modality for delineating course and drainage pattern of dorsal and ventral PDs ○ No communication between dorsal and ventral ducts in pancreatic divisum – Dominant dorsal duct, which appears long and narrow, directly enters minor papilla □ Majority of pancreas is thus drained into minor papilla via duct of Santorini □ Dorsal duct may have constant, mildly dilated caliber (rather than normal tapering towards tail) □ Focal cystic dilatation of duct of Santorini is termed "santorinocele" and easily visible on MRCP □ Anatomic relationship between dorsal duct and common bile duct on MRCP MIP reconstruction results in characteristic crossing ducts sign – Ventral duct appears short and drains into major papilla, with no connection with dorsal duct □ Posterior pancreatic head and uncinate drain into major papilla via duct of Wirsung ○ Main PD may be dilated due to stenosis at minor papilla or repeated bouts of pancreatitis • Pancreas may demonstrate abnormally high signal on T2WI and low signal on T1WI with peripancreatic free fluid in setting of superimposed pancreatitis • Secretin-enhanced MRCP may help better delineate divisum by distending PD ○ Secretin (0.2 μg/kg) induces secretion of bicarbonate-rich fluid from pancreas and increases tone of sphincter of Oddi, thereby distending PD and improving visualization ○ Secretin-enhanced MR shown to have superior sensitivity/specificity for divisum compared to MR without secretin

CT Findings • Delineating pancreatic ductal anatomy is more difficult on CT (compared to MR), but may be aided by multiplanar and minimum intensity projection reconstructions with thincollimation sections ○ Dorsal duct, which may be dilated, can be directly traced from pancreatic tail into minor papilla ○ Ventral duct is smaller (may be difficult to visualize on CT) and drains into major papilla

Pancreas

TERMINOLOGY

Ultrasonographic Findings • Secretin test can be performed to identify patients who will benefit from surgical sphincterotomy ○ Involves sequential US measurements of PD size after secretin administration – Secretin increases bicarbonate secretion, which overloads functionally inadequate papilla – Secretin-induced ductal dilatation occurs in 72% of symptomatic patients due to stenotic minor or accessory papilla in pancreas divisum anomaly

Imaging Recommendations • Best imaging tool ○ Secretin-enhanced MRCP or ERCP

DIFFERENTIAL DIAGNOSIS Pancreatic Ductal Carcinoma • When located in head, may mimic divisum on ERCP (or MRCP) with abrupt narrowing and occlusion of ventral duct ○ ERCP and MRCP: PD at site of obstruction appears irregular and abnormally truncated, unlike divisum where ventral duct appears short, but maintains normal branching pattern • Distinction readily made on CECT or MR, with heterogeneous, hypoenhancing mass in pancreatic head, abrupt obstruction and upstream dilatation of PD, locoregional invasion, and distant metastases

Chronic Pancreatitis • May result in PD obstruction and upstream dilatation that mimics divisum, with abrupt narrowing and truncation of ventral duct • Focal or diffuse glandular atrophy with heterogeneous enhancement and dilated, beaded PD ○ ± intraductal calculi and parenchymal calcification 983

Pancreas

Pancreas Divisum ○ ± focal fibroinflammatory mass that can mimic malignancy ○ ± intrapancreatic or peripancreatic pseudocysts

Agenesis of Dorsal Pancreas • ERCP appearance (with injection of contrast into Wirsung duct) may be identical to pancreas divisum ○ Contrast injected into major papilla does not flow past pancreatic head • Diagnostic key: Absence of pancreatic body/tail on CT or MR

Annular Pancreas • Congenital anomaly that results in pancreatic tissue partially or completely encircling descending duodenum • Enlarged pancreatic head encircling 2nd portion of duodenum on CT or MR • ERCP and MRCP: Main PD encircling duodenum and abnormally extending to right side of duodenum

Other Anatomic Variants of Pancreatic Ductal Anatomy • Multiple configurations of PD are possible, including bifid configuration of dorsal and ventral ducts, duplication anomalies of MPD, ansa pancreatica (duct of Santorini forms sigmoid curve as it joins with ventral duct), and rudimentary or dominant dorsal duct

PATHOLOGY General Features • Etiology ○ Normal embryology: Ventral pancreas rotates posterior to duodenum and fuses with dorsal pancreas in 8th week of gestation – Failure of fusion of dorsal and ventral ductal system results in pancreas divisum – Parenchymal fusion almost always occurs, although there may be textural differences between dorsal and ventral gland, or intervening tissue plane • Associated abnormalities ○ Annular pancreas ○ Partial agenesis of dorsal pancreas ○ Elevated pressures at sphincter of Oddi ○ No definite link with malignancy, although some reports suggest increased incidence of pancreatic cancer, cholangiocarcinoma, and ampullary cancer • Anatomy of pancreas divisum ○ Dorsal PD drains pancreatic anterior head, neck, body, and tail via long and narrow (and sometimes dilated) duct of Santorini into minor papilla – Poor drainage of secretions from body and tail (as result of relative stenosis at minor papilla) results in increased stasis and ductal pressure repeated bouts of pancreatitis – Typically pancreatic head (ventral pancreas) is spared in these bouts of pancreatitis ○ Ventral PD drains head and uncinate process via short duct of Wirsung – Alcoholics may develop pancreatitis due to reflux of bile via short duct of Wirsung □ Body and tail (dorsal pancreas) are spared in such cases due to pancreas divisum 984

Staging, Grading, & Classification • May be subdivided into 3 types ○ Type I (Classic divisum): No communication between dominant dorsal duct and small ventral duct ○ Type II: Duct of Wirsung is completely absent ○ Type III (Partial divisum): Small branches of ventral duct may retain communication with dorsal duct

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most cases are asymptomatic ○ Epigastric pain, nausea, and vomiting possible due to pancreatitis, with symptoms depending on severity – May be induced by overeating or alcohol consumption – < 5% of patients experience pancreas-related symptoms ○ May be seen in multiple family members

Demographics • Age ○ Varies widely at diagnosis ○ Common between 30-50 years • Gender ○ M>F • Epidemiology ○ Most common congenital anatomic variant of pancreas ○ 3-6% of general population – 4-11% of autopsy series and 3-4% of ERCP series ○ May be present in 12-26% of patients with idiopathic recurrent pancreatitis

Natural History & Prognosis • Complications ○ Recurrent pancreatitis (mostly in children) ○ Pancreaticolithiasis, serous cystadenoma (speculative)

Treatment • Incidental finding in asymptomatic patient: No treatment • Symptomatic patients (i.e., repetitive pancreatitis) ○ Patients with mild symptoms may be managed conservatively or given pancreatic enzyme therapy ○ Severely symptomatic patients may respond to surgical or endoscopic sphincteroplasty/papillotomy of minor papilla

DIAGNOSTIC CHECKLIST Consider • Rule out other causes of apparent pancreatic duct obstruction and differentiate from other anatomic variations of pancreatic ductal anatomy

SELECTED REFERENCES 1.

Tirkes T et al: Secretin-enhanced MR cholangiopancreatography: spectrum of findings. Radiographics. 33(7):1889-906, 2013

Pancreas Divisum Pancreas

(Left) MRCP shows the main pancreatic duct entering the minor papilla and the common bile duct entering the duodenum at the major papilla. The relationship between the pancreatic and common duct is referred to as the crossing duct sign. (Right) Gadolinium-enhanced T1weighted MR in the same patient demonstrates the main pancreatic duct entering the duodenum via the minor papilla . The common bile duct is seen posteriorly as its enters the duodenum via the major papilla.

(Left) Axial CECT shows a dilated pancreatic duct and small pseudocysts in a patient with pancreas divisum complicated by recurrent episodes of pancreatitis. (Right) More caudal axial CECT in the same patient shows a calculus within the duct of Santorini, which is of normal caliber downstream as it enters the minor papilla. The stone was confirmed and removed at ERCP, during which a pancreatic stent was also placed.

(Left) MRCP shows a dilated CBD with a distal stricture due to prior pancreatitis. The main pancreatic duct (MPD) is seen in the body and tail. Note the separate duct of Wirsung from the head and uncinate, indicating divisum. (Right) MRCP in same patient following administration of secretin shows interval dilatation of the MPD without fluid accumulating in the duodenum, indicating a stricture at the minor papilla, likely the cause of the patient's episodes of pancreatitis.

985

Pancreas

Asymmetric Fatty Lobulation of the Pancreas KEY FACTS

TERMINOLOGY

TOP DIFFERENTIAL DIAGNOSES

• Focal accumulation of fat within anterior aspect of head of pancreas, a normal variant that may simulate a hypodense mass on CT

• • • •

IMAGING • Low-attenuation area on CT within anterior head of pancreas ○ Triangular with sharp, linear margin between normal pancreas and area of fatty infiltration • Lack of mass effect or dilatation of common bile duct or pancreatic duct • Pancreas maintains normal external contour and normal pancreatic lobulations • Chemical shift MR (in- and out-of-phase imaging) most specific modality for making a definitive diagnosis in confusing cases ○ Signal dropout in areas of fatty infiltration on opposedphase images

(Left) Axial arterial phase CECT demonstrates a lowattenuation area anteriorly within the head of the pancreas. Note the normally enhancing uncinate process posterior to this area, as well as the sharp linear boundary demarcating the low attenuation area. (Right) A coronal curved planar reformation along the pancreatic duct demonstrates a normal duct. The characteristic location and the lack of mass effect on the duct are key findings to suggest the diagnosis of focal fatty infiltration.

(Left) Axial in-phase GRE MR image demonstrates uniform signal in the head of the pancreas . (Courtesy H. Harvin, MD.) (Right) Axial opposed-phase MR in the same patient shows dropout of signal in the anterior aspect of the head, a classic finding confirming asymmetric fatty lobulation. Note the preserved higher signal and lack of dropout from the normal pancreatic tissue in the uncinate process . (Courtesy H. Harvin, MD.)

986

Pancreatic head adenocarcinoma Focal pancreatitis Diffuse fatty replacement of pancreas Intrapancreatic lipoma

PATHOLOGY • Dorsal pancreatic bud develops into body, tail, and anterior head of pancreas, while ventral bud develops into posterior head and uncinate process • Fat accumulates preferentially within anterior head of pancreas derived from dorsal foregut bud • May reflect more tightly packed pancreatic lobules in ventral bud compared to dorsal bud

CLINICAL ISSUES • Incidental finding in asymptomatic patients • No association with endocrine or exocrine abnormalities

Asymmetric Fatty Lobulation of the Pancreas

Synonyms • Focal lipomatosis or focal fatty infiltration of pancreas

Definitions • Focal accumulation of fat within anterior aspect of head of pancreas, a normal variant that may simulate a hypodense mass on CT

IMAGING General Features • Best diagnostic clue ○ Ill-defined, low-attenuation area (without mass effect or ductal dilatation) in anterior head of pancreas • Location ○ Anteriorly within head of pancreas (corresponds to dorsal bud in embryologic development) ○ Often spares region around intrapancreatic common bile duct (CBD) • Size ○ Typically 2-3 cm • Morphology ○ Often ill-defined area with geographic distribution ○ Triangular or plate-like shape ○ May have straight interface with normal-appearing uncinate process and posterior pancreatic head

Diffuse Fatty Replacement of Pancreas • Associated with cystic fibrosis, lipomatous pseudohypertrophy, and senescent fatty replacement

Intrapancreatic Lipoma • Rare fat-containing mass with well-defined margins within pancreatic parenchyma

PATHOLOGY General Features • Etiology ○ Dorsal pancreatic bud develops into body, tail, and anterior head of pancreas, while ventral bud develops into posterior head and uncinate process ○ Fat accumulates preferentially within anterior head of pancreas derived from dorsal foregut bud ○ May reflect more tightly packed pancreatic lobules in ventral bud compared to dorsal bud

Staging, Grading, & Classification • Type I fatty infiltration involves only anterior head of pancreas with sparing of posterior head and uncinate (70%) • Type II fatty infiltration involves entire head and uncinate process with sparing around common bile duct (30%) • May be present in up to 3% of all patients

Gross Pathologic & Surgical Features • Yellowish fat intermixed with normal pancreatic lobules

CT Findings

Microscopic Features

• Low-attenuation area within anterior head of pancreas ○ Triangular with sharp, linear margin between normal pancreas and area of fatty infiltration • No abnormal enhancement in fatty area • No mass effect or dilatation of CBD or pancreatic duct (PD) • Pancreas maintains normal external contour and normal pancreatic lobulations • Unlike lipoma, not a discrete fatty mass (-20 to -80 HU)

• Adipose cells intermixed with normal pancreatic ductal and islet cells

MR Findings • Chemical shift MR (in- and out-of-phase imaging) is most specific modality for making definitive diagnosis • Signal dropout in areas of fatty infiltration on opposedphase images

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Incidental finding in asymptomatic patients ○ No association with endocrine or exocrine abnormality

Natural History & Prognosis • No clinical significance

DIAGNOSTIC CHECKLIST

Ultrasonographic Findings

Consider

• Areas of fatty infiltration appear abnormally hyperechoic • Can create impression of hypoechoic uncinate lesion due to echogenic fatty infiltration in adjacent anterior head

• Pancreatic carcinoma if contour abnormality or obstruction of PD or CBD • Pancreatic lipoma if discrete, well-defined area of fat attenuation with no enhancement

Imaging Recommendations • Best imaging tool ○ MR with chemical shift imaging

DIFFERENTIAL DIAGNOSIS Pancreatic Head Adenocarcinoma • Hypodense lesion with mass effect obstructing PD or CBD • Contour deformity of pancreas with loss of normal fatty lobulations

Pancreas

TERMINOLOGY

Image Interpretation Pearls • Area of ill-defined hypoattenuation on CT characteristically located within anterior head of pancreas • Shows signal loss on opposed-phase chemical shift MR

SELECTED REFERENCES 1.

Pokharel SS et al: Current MR imaging lipid detection techniques for diagnosis of lesions in the abdomen and pelvis. Radiographics. 33(3):681702, 2013

Focal Pancreatitis • Low-attenuation area with peripancreatic inflammation 987

Pancreas

Ectopic Pancreatic Tissue KEY FACTS

TERMINOLOGY • Pancreatic tissue located outside of normal confines of pancreas and lacking any anatomic or vascular connection with main pancreas

IMAGING • 90% in upper GI tract (stomach, duodenum, proximal jejunum) • Fluoroscopic findings ○ Well-defined, smoothly marginated, round/oval submucosal mass with central umbilication ○ Reflux of contrast into rudimentary duct-like structure may extend below central pit • CT findings ○ Often too small to be detected ○ Round or oval mass with protrusion into gut lumen ○ May have well-defined or ill-defined margins on CT ○ Enhancement pattern is variable

(Left) Axial CECT demonstrates a mural mass in the body of the stomach. Note that the mass enhances similarly to the normal pancreas. Endoscopic biopsy revealed ectopic pancreatic tissue. (Right) Axial CECT in a patient with abdominal pain demonstrates a cystic intramural mass within the distal stomach, found to represent ectopic pancreas after surgery. Ectopic pancreas can appear homogeneous, heterogeneous, or cystic depending on its internal mixture of acini, ducts, and islet cells.

(Left) Upper GI series spot film shows a small antral mass with intact mucosa. A central "dot" of barium can be seen filling a rudimentary duct. (Right) Upper GI image shows a small, smooth, intramural mass along the greater curvature of the antrum without central umbilication. Only 45% of patients with ectopic pancreas will have central umbilication on a barium study. In the absence of this sign, it is difficult to distinguish ectopic pancreas from other intramural masses, such as metastasis or GIST.

988

– Acini-dominant ectopic pancreas shows homogeneous, avid enhancement – Others types more heterogeneous (or even cystic) • MR findings: Ectopic pancreas is isointense on all pulse sequences with main pancreas (including DWI/ADC)

TOP DIFFERENTIAL DIAGNOSES • • • •

Gastric GIST Gastric ulcer Gastric carcinoma Gastric metastases and lymphoma

CLINICAL ISSUES • Most patients are asymptomatic and ectopic pancreas is usually an incidental finding • Can be complicated by bleeding or mucosal ulceration and patients present with epigastric pain and melena • Can undergo any of the inflammatory or neoplastic abnormalities of main pancreas including acute/chronic pancreatitis and development of malignancy

Ectopic Pancreatic Tissue

Definitions • Pancreatic tissue located outside of normal confines of pancreas and lacking any anatomic or vascular connection with main pancreas

IMAGING General Features • Best diagnostic clue ○ Small submucosal gastric mass with central umbilication – Central umbilication (45% of cases): Orifice of rudimentary duct through which ectopic pancreatic tissue (EPT) drains into gastric lumen • Location ○ 90% of all cases found in upper GI tract (stomach, duodenum, or proximal jejunum) – Most commonly gastric antrum (< 6 cm from pylorus) ○ Primarily arise in submucosa (73%); can also be located in muscular layer (17%) or subserosa (10%) • Size ○ Nodule: 0.5-2 cm; may be up to 5 cm in diameter ○ Pit: May be 5 mm in diameter and 10 mm in length

Radiographic Findings • Ability to visualize EPT depends on size/location of deposit • Well-defined, smoothly marginated, round or oval submucosal mass with central umbilication ○ Typically 1-2 cm in diameter, along greater curvature or posterior aspect of antrum, and within 6 cm of pylorus ○ Nodule may be larger, narrow-based, and polypoid in appearance, or located in more proximal antrum • Central umbilication is a specific feature: Central depression with contrast filling pit in center of mound ○ May be mistaken for ulcerative lesion ○ Reflux of contrast into rudimentary duct-like structure may extend below central pit • Upper GI series may show narrowed pyloric channel ± polypoid or sessile mass

CT Findings • Often too small to be detected on CT • Round or oval mass with tendency for endoluminal growth (protrusion into gut lumen) ○ May have well-defined or ill-defined margins • Enhancement pattern is variable ○ Acini-dominant ectopic pancreas shows homogeneous, avid enhancement ○ Others types with mixture of acini and ducts may appear more heterogeneous (and sometimes even cystic) ○ Overlying mucosa avidly enhancing as a result of inflammation • Central umbilication not typically visualized on CT

MR Findings

DIFFERENTIAL DIAGNOSIS

Pancreas

○ Central umbilication may be visualized, and, if injected, rudimentary duct system may be seen

TERMINOLOGY

Gastric Ulcer • Round ulcer, smooth mound of edema, radiating folds to ulcer edge, Hampton line, ulcer collar

Gastric GIST • Submucosal mass with frequent ulceration, tendency for exophytic growth, and variable enhancement on CT/MR

Other Gastric Hypervascular Submucosal Lesions • Glomus tumor, carcinoid tumors, and some GISTs appear as hypervascular masses on CT/MR within submucosa

Gastric Carcinoma • Polypoid or circumferential mass, ± ulceration, focal wall thickening with mucosal irregularity

Gastric Metastases and Lymphoma • May show bull's-eye sign: Ulceration in center of lesion

PATHOLOGY Microscopic Features • May contain all or only some elements of normal pancreas, including acini, ducts, and islet cells

CLINICAL ISSUES Presentation • Most patients are asymptomatic: Incidental finding • Most common symptoms: Epigastric pain and melena ○ May cause symptoms of pyloric obstruction when located in stomach

Demographics • Epidemiology ○ Incidence of autopsy series: 2-14%

Natural History & Prognosis • Often complicated by bleeding or mucosal ulceration • Can undergo any of the inflammatory or neoplastic abnormalities of main pancreas ○ Acute or chronic pancreatitis ± typical complications ○ Development of ductal adenocarcinoma

Treatment • Surgical intervention for obstruction or hemorrhage • Endoscopic resection if lesion confined to submucosa • May be treated expectantly when asymptomatic

DIAGNOSTIC CHECKLIST Consider • If central umbilication is absent, lesion may not be differentiated from other submucosal tumors

• Isointense on all pulse sequences with main pancreas

Other Modality Findings • Endoscopy: More capable of identifying EPT when nodule is small and located in duodenum

SELECTED REFERENCES 1.

Jang KM et al: Ectopic pancreas in upper gastrointestinal tract: MRI findings with emphasis on differentiation from submucosal tumor. Acta Radiol. 54(10):1107-16, 2013

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Pancreas

Acute Pancreatitis and Complications KEY FACTS

TERMINOLOGY • Acute inflammation of pancreas with variable involvement of other regional tissues or remote organs

IMAGING • Interstitial edematous pancreatitis (70-80% of cases): Normal enhancement of pancreas without necrosis ○ Pancreas typically enlarged and edematous with loss of normal fatty lobulation ○ Peripancreatic fat stranding, edema, and free fluid ○ Mild edematous pancreatitis can appear normal on CT • Necrotizing pancreatitis (20-30% of cases): Areas of parenchymal necrosis which are either nonenhancing or severely hypoenhancing ○ Differentiate cases with 30% necrosis from > 30% necrosis for patient prognosis ○ Necrosis may not be present initially, but can develop 3-4 days after symptom onset • Complications

(Left) Axial CECT in an alcoholic patient demonstrates that although the pancreas itself does not appear appreciably enlarged, there is subtle peripancreatic fat stranding and edema, compatible with mild edematous pancreatitis. (Right) Axial CECT in a patient after ERCP with placement of a stent demonstrates enlargement of the pancreas, edema with loss of normal fatty lobulation, and peripancreatic fat stranding and fluid, compatible with acute edematous pancreatitis.

(Left) Axial CECT in a patient with abdominal pain demonstrates enlargement and edema of the pancreas with surrounding fluid and stranding, compatible with acute edematous pancreatitis. The entire gland enhances normally without evidence of necrosis. (Right) Transverse ultrasound demonstrates diffuse enlargement of the pancreas , which appears abnormally hypoechoic, compatible with acute pancreatitis in this patient with a markedly elevated lipase level.

990

○ Infected pancreatic necrosis: Ectopic gas, in absence of intervention, highly suggestive of infected necrosis ○ Central necrosis: Necrosis of central portion of gland/duct with intact pancreas/duct in head and tail ○ Pseudoaneurysm: Most common locations are splenic (50%) gastroduodenal (20%), and pancreaticoduodenal (10%) arteries, but any artery can be involved ○ Venous thrombosis: Splenic vein most common, but portal veins or SMV can be involved ○ Fluid collections: Nomenclature depends on age of collection and edematous vs. necrotizing pancreatitis

PATHOLOGY • Alcohol and gallstones account for vast majority of cases

CLINICAL ISSUES • Overall mortality rate: 5%, with excellent prognosis for interstitial edematous pancreatitis • Poor prognosis with complications: Mortality of 25% with multiorgan failure or ~ 30% for infected necrosis

Acute Pancreatitis and Complications

Definitions

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• Acute inflammation of pancreas with variable involvement of other regional tissues or remote organs

IMAGING General Features • Best diagnostic clue ○ Enlarged, edematous pancreas with peripancreatic fluid, fat stranding, and fluid collections

CT Findings • Revised Atlanta classification in 2012 standardized nomenclature used to describe acute pancreatitis • 2 primary subtypes of acute pancreatitis ○ Interstitial edematous pancreatitis (70-80% of cases) – Pancreas typically enlarged and edematous with loss of normal fatty lobulation – Peripancreatic fat stranding, edema, and free fluid (with fluid most often localized to lesser sac, anterior pararenal spaces, and paracolic gutters) – Usually diffuse edema of entire gland, but can rarely be focal and involve just a segment of pancreas – Normal enhancement of pancreas without necrosis – Normal appearance of pancreas does not exclude pancreatitis: Mild pancreatitis, usually with minimally elevated lipase levels, can appear normal on imaging ○ Necrotizing pancreatitis (20-30% of cases): Areas of parenchymal necrosis which are either nonenhancing or severely hypoenhancing (usually < 30 HU) – Usually greater degree of peripancreatic fluid and inflammation than edematous pancreatitis – Differentiate cases with 30% parenchymal necrosis from > 30% necrosis for patient prognosis – Necrosis may not be present initially, but can develop 3-4 days after symptom onset □ Early CT can underestimate or miss necrosis – Revised Atlanta classification system describes 3 subtypes of necrotizing pancreatitis □ Parenchymal necrosis alone in 5% □ Parenchymal and peripancreatic necrosis in 75% □ Peripancreatic necrosis alone in 20% (exudative pancreatitis) • Complications ○ Infected pancreatic necrosis – Implies superinfection of necrotic parenchyma and carries very poor prognosis – Ectopic gas in pancreatic bed, in absence of intervention, virtually diagnostic of infected necrosis – No other specific findings, although inflammation usually greater in cases with infected necrosis □ May require aspiration for culture in cases with no definitive imaging findings ○ Central necrosis (disconnected duct syndrome) – Necrosis of central portion of gland and pancreatic duct with intact upstream and downstream pancreas/duct in head and tail – Results in fluid collection in necrotic gland with continual leakage of pancreatic juice into collection

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– Collection may require either internal drainage or surgery (usually distal pancreatectomy) Extrapancreatic fat necrosis – Due to leakage of pancreatic enzymes into peripancreatic soft tissues resulting in fat necrosis – Usually low density with heterogeneous fluid and solid components, but can appear nodular and mass-like, mimicking carcinomatosis – Most often occurs surrounding pancreas, anterior mesentery, or anterior pararenal spaces – Carries better prognosis than parenchymal necrosis but worse than edematous pancreatitis Pseudoaneurysm – Small contrast-filled outpouching arising next to artery ± adjacent hematoma (due to leak or rupture) – Most common locations are splenic (50%) gastroduodenal (20%), and pancreaticoduodenal (10%) arteries, but any artery can be involved – Unexplained hemorrhage in pancreatic bed should prompt careful search for pseudoaneurysm Venous thrombosis – May occur due to either direct intimal injury to vessel from adjacent inflammation and pancreatic enzymes or due to mass effect from adjacent collections – Splenic vein most often involved, but portal veins or SMV can be involved as well Fluid collections – Acute peripancreatic fluid collection: Fluid collection first 4 weeks after acute edematous pancreatitis □ Simple, nonloculated collection of fluid attenuation with no internal debris or hemorrhage – Pseudocyst: Fluid collection persisting > 4 weeks after acute edematous pancreatitis □ Loculated collection with a well-defined enhancing wall of granulation tissue most often arising in lesser sac or pararenal spaces □ Simple collection of fluid attenuation with no internal debris or hemorrhage – Acute postnecrotic fluid collection: Fluid collection first 4 weeks after acute necrotizing pancreatitis □ Nonloculated, but containing internal necrotic debris and blood products □ Acute complex fluid collection with internal debris and solid material in setting of a normally enhancing gland suggests acute postnecrotic fluid collection due to extrapancreatic necrosis – Walled-off necrosis: Loculated fluid collection persisting > 4 weeks after necrotizing pancreatitis □ Heterogeneous collection with a well-defined wall and internal necrotic debris/blood products – "Pancreatic abscess": Term no longer utilized in revised Atlanta classification "Hemorrhagic" pancreatitis:Term not included in Atlanta classification – Small amounts of blood frequently present in peripancreatic fluid collections and has no direct impact on disease severity

Pancreas

TERMINOLOGY

MR Findings • Pancreas appears enlarged with increased signal on T2WI and abnormally low signal on T1WI due to edema 991

Pancreas

Acute Pancreatitis and Complications

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•

•

○ Fat suppression very important in highlighting edema and fluid around pancreas on T2WI T1WI C+ images similar to CECT in detection of pancreatic necrosis and nonenhancement T2WI offers advantage (over CT) of allowing differentiation of simple fluid collections from collections with internal solid debris (i.e., walled off necrosis) MRCP can evaluate integrity of pancreatic duct, particularly in patients with suspected central gland necrosis ○ May be able to delineate communication between a fluid collection and pancreatic duct ○ Can delineate anatomic variants which might predispose to pancreatitis, including pancreatic divisum ○ Very sensitive for gallstones and other biliary pathology as cause of pancreatitis Acute pancreatitis may be associated with restricted diffusion (lower ADC values than normal pancreas)

Ultrasonographic Findings • Enlarged, hypoechoic pancreas with adjacent free fluid and blurring of pancreatic margins ○ Pancreas may appear normal in mild cases • Ultrasound often performed at presentation to look for gallstones

Radiographic Findings • Radiography ○ Evidence of localized ileus due to adjacent inflammation, including dilated duodenum or sentinel loop sign (mildly dilated, gas-filled segment of small bowel ± air-fluid levels) ○ Colon cutoff sign: Markedly distended air-filled transverse colon with absence of gas distal to splenic flexure due to functional colonic spasm (spread of pancreatic inflammation to proximal descending colon)

Imaging Recommendations • Best imaging tool ○ Dual-phase (arterial and venous) CECT best initial study ○ MR with MRCP helpful problem-solving tool to assess pancreatic duct or composition of fluid collections

DIFFERENTIAL DIAGNOSIS Infiltrating Pancreatic Carcinoma • Heterogeneous, hypoenhancing mass with abrupt obstruction of upstream pancreatic duct and upstream pancreatic atrophy • Pancreatic cancer may present with pancreatitis in ~ 5% of cases • Focal pancreatitis can appear mass-like and mimic malignancy • Presence of dilated pancreatic duct or biliary obstruction should prompt further investigation for underlying mass • Pancreatic cancer infiltrates dorsally into retroperitoneum, unlike pancreatitis, which infiltrates anteriorly and laterally • Usually other signs of malignancy, including vascular encasement, metastatic disease (most often liver), etc.

Perforated Duodenal Ulcer • Can cause fat stranding and edema in anterior pararenal space and mimic pancreatitis 992

• Pancreatic head may be edematous due to adjacent inflammation • Inflammation primarily centered around duodenum, not pancreas (often more apparent on coronal reformations) • < 50% show extraluminal gas or contrast extravasation

"Shock" Pancreas • "Shock" complex can include infiltration of peripancreatic fat planes with pancreatic edema (similar to pancreatitis) • Usually associated with clinical history of hypotension and other imaging stigmata of shock, such as "shock bowel" • Quickly resolves following resuscitation

Lymphoma • Lymphoma can rarely diffusely infiltrate and enlarge pancreas, superficially mimicking pancreatitis • Usually associated with regional lymphadenopathy and pancreatic involvement appears mass-like • No evidence of pancreatic or biliary ductal dilatation • Vessels encased, but not narrowed or occluded

PATHOLOGY General Features • Etiology ○ Alcohol (35%) and gallstones (~ 40%) account for vast majority of cases – Larger gallstones more likely to cause pancreatitis as they lodge in sphincter of Oddi – More common with long history of alcohol, although can occur after single binge drinking episode ○ Many other causes, including metabolic disorders (e.g., hypertriglyceridemia, hypercalcemia), infection, trauma, drugs, anatomic variants (e.g., pancreatic divisum, annular pancreas), neoplasm (e.g., pancreatic adenocarcinoma or IPMN), iatrogenic (e.g., ERCP), etc. ○ No cause identified for pancreatitis in 1/3 of cases – Some theorize that many of these cases are attributable to tiny gallstones ○ Exact pathogenesis of acute pancreatitis unclear and may vary depending on etiology – Possibilities include reflux of pancreatic enzymes, bile, and duodenal contents into pancreatic duct, increased ductal pressure due to ampullary obstruction, or activation of intracellular/extracellular homeostatic factors – Pancreatic enzymes activated and released into surrounding soft tissues causing inflammation and autodigestive injury to pancreas – 2 phases of acute pancreatitis: Early and late □ Early phase over 1st week and is characterized by systemic inflammatory response syndrome (SIRS) □ Late phase (only seen in severe cases) occurs after 1st week and is characterized by local complications and persistent systemic inflammation • Genetics ○ Hereditary pancreatitis associated with several gene mutations (PRSS1, CFTR, etc.)

Staging, Grading, & Classification • Balthazar CT severity index from 1990 (10 point max) ○ A: Normal pancreas (0 point) ○ B: Enlarged pancreas (1 point)

Acute Pancreatitis and Complications

C: Peripancreatic fat stranding and edema (2 points) D. Single peripancreatic fluid collection (3 points) E: 2 peripancreatic fluid collections or gas (4 points) Pancreatic necrosis: None (0 points), 30% (2 points), 3150% (4 points), > 50% (6 points) ○ Mild pancreatitis: 0-3 points ○ Intermediate: 4-6 points ○ Severe pancreatitis: 7-10 points • Modified CT severity index from 2004 (10 point max) ○ Normal pancreas (0 points) ○ Pancreatic edema and inflammation (2 points) ○ Pancreatic or peripancreatic fluid collection or extrapancreatic fat necrosis (4 points) ○ Pancreatic necrosis: None (0 points), 30% (2 points), > 30% (4 points) ○ Extrapancreatic complications (pleural effusion, ascites, vascular complication, etc.): 2 points

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute epigastric pain, which often radiates to back ○ Abdominal tenderness, abdominal distension, fever, nausea, vomiting – Symptoms often improve when patient is supine ○ Fever and sepsis in setting of necrotizing pancreatitis raises concern for infected necrosis ○ Physical examination findings of necrotizing pancreatitis (± hemorrhage) – Grey Turner sign: Bluish discoloration of flanks – Cullen sign: Periumbilical discoloration ○ 2 of 3 features required to make clinical diagnosis of acute pancreatitis – Elevated amylase/lipase (3x normal limits) – Characteristic clinical history – Characteristic imaging findings • Lab data ○ serum amylase and lipase, with lipase more sensitive and specific than amylase ○ ALT suggests biliary etiology (usually gallstones)

Demographics • Age ○ Can be seen in any age group and varies depending on etiology, but most common in young and middle aged • Gender ○ M > F (more commonly due to alcohol in males, gallstones in females) • Epidemiology ○ Incidence in USA: 0.005-0.01% of general population ○ 300,000 per year admitted for acute pancreatitis in USA ○ USA: Alcoholic pancreatitis more common in urban and VA hospitals; gallstone pancreatitis more common in suburban and rural settings

Natural History & Prognosis • Prognosis ○ Overall mortality rate of 1-3%, with excellent prognosis for interstitial edematous pancreatitis

○ Poor prognosis in setting of complications: Mortality rate: 25% with multiorgan failure or ~ 30% for infected necrosis (even with surgical debridement) ○ Mortality in early stage of illness due to multiorgan failure, while later mortality mostly due to infection • Natural evolution of fluid collections ○ Acute peripancreatic fluid collections: Develop in first 48 hours and ~ 50% spontaneously resolve within 2-4 weeks ○ Pseudocysts occur in 10-20% of cases and communicate with pancreatic duct in up to 60% of cases – 50% of pseudocysts are asymptomatic and resolve spontaneously over time – Only 25% of pseudocysts are symptomatic due to infection, mass effect, pain, gastric outlet obstruction, etc.

Pancreas

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Treatment • Initial treatment is conservative, including fluid resuscitation, pain control, n.p.o. (nothing by mouth) with nutritional support until patient can resume oral diet, and antibiotics (only if infection is suspected) ○ Early ERCP and sphincterotomy in patients with suspected gallstone pancreatitis only in setting of cholangitis or cholestasis ○ Most patients with interstitial edematous pancreatitis will resolve with conservative measures alone ○ Severe pancreatitis with necrosis may require intensive care due to high risk of multiorgan failure • Infected pancreatic necrosis may require surgical debridement (necrosectomy), although surgery typically deferred until 4 weeks after presentation to allow collections to become walled off ○ Image-guided fine-needle aspiration may be utilized to distinguish sterile necrosis from infected necrosis if infection suspected and no response to antibiotics • Asymptomatic fluid collections do not warrant intervention (either drainage, aspiration, or surgery) ○ Symptomatic fluid collections (due to mass effect, infection, pain, etc.) may be drained, with walled-off necrosis requiring large-bore catheter or necrosectomy (due to debris and solid components), while simpler fluid collections can be drained with standard catheters • Angiographic embolization for pseudoaneurysms and anticoagulation for venous thrombosis involving portal vein or SMV

DIAGNOSTIC CHECKLIST Consider • Differentiate pancreatitis from other causes of inflammation centered in adjacent structures, such as a perforated duodenal ulcer • Pancreatic duct obstruction or infiltration posteriorly into retroperitoneum should suggest presence of an underlying mass, rather than routine acute pancreatitis

SELECTED REFERENCES 1.

Baker ME et al: ACR Appropriateness Criteria® Acute Pancreatitis. Ultrasound Q. 30(4):267-73, 2014

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Pancreas

Acute Pancreatitis and Complications

(Left) Transverse US demonstrates mild diffuse enlargement of the pancreas. The pancreatic duct is normal in size . The main sign of acute pancreatitis is fluid anterior to the pancreas as well as fluid anterior to the splenic vein . (Right) Longitudinal US of the body of the pancreas demonstrates peripancreatic fluid tracking caudally down the superior mesenteric vein . There is also fluid noted anterior to the body of the pancreas , a strong clue to the diagnosis of acute pancreatitis.

(Left) Axial T2-weighted MR demonstrates mild diffuse enlargement of the pancreas with linear bands of high signal representing intraparenchymal edema . (Right) Axial T2-weighted MR at a more cranial level in the same patient shows marked heterogeneity of the pancreas with areas of parenchymal edema and peripancreatic fluid consistent with edematous pancreatitis. Fatsuppressed T2WI is the most critical pulse sequence for highlighting changes of acute pancreatitis on MR.

(Left) (Left) Supine radiograph shows a dilated transverse colon with abrupt "cut-off" and narrowing of the colon at the splenic flexure. (Right) Axial CECT in the same patient shows thickening of the descending colon as a result of the adjacent pancreatic inflammation, causing the colon cut-off sign. Note the posterior interfascial extension of fluid with preserved fat in the posterior pararenal space .

994

Acute Pancreatitis and Complications Pancreas

(Left) Axial CECT at presentation in a patient with abdominal pain demonstrates findings of acute edematous pancreatitis, with enlargement of the pancreas and significant peripancreatic free fluid. (Right) Axial CECT acquired 3 days later due to the patient's clinical deterioration demonstrates that the patient now has findings of acute necrotizing pancreatitis, with only a small portion of the pancreatic body still enhancing. Early CT (< 72 hours) can miss or underestimate pancreatic necrosis.

(Left) Axial T2 FS MR demonstrates replacement of the normal pancreas with high T2 fluid signal due to necrotizing pancreatitis. The more hypointense T2 signal in the pancreatic bed represents a combination of residual viable pancreatic tissue and necrotic debris. (Right) Axial T1WI C+ MR in the same patient better demonstrates that the patient has severe necrotizing pancreatitis, with only a small portion of the body still enhancing.

(Left) Coronal MRCP in the same patient demonstrates that despite this extensive necrosis, the pancreatic duct still appears intact, a valuable piece of information for the gastroenterologist. Evaluation of the pancreatic duct is a significant advantage of MR compared to CT. (Right) Axial CECT in a patient with abdominal pain demonstrates that only a small portion of the pancreatic tail is still normally enhancing, with nonenhancement of the remainder of the pancreas, compatible with necrotizing pancreatitis.

995

Pancreas

Acute Pancreatitis and Complications

(Left) Axial CECT shows extensive pancreatic necrosis with complete lack of enhancement of the body and head of the pancreas . Note the marked peripancreatic inflammation and thrombus in the portal vein . (Right) Axial CECT at a lower plane of section in the same patient shows focal necrosis in the head of the pancreas . Note the thrombus extending into the superior mesenteric vein and marked inflammation of the mesentery . The patient soon expired from multiorgan failure.

(Left) Axial CECT in a patient with necrotizing pancreatitis shows an acute postnecrotic fluid collection centered in the pancreatic bed with little remaining enhancing pancreas. The ectopic gas in the pancreatic bed is virtually diagnostic of infected necrosis, and the patient ultimately underwent necrosectomy. (Right) Axial CECT demonstrates the characteristic findings of infected pancreatic necrosis, with nonenhancement of the entire pancreas and multiple foci of ectopic gas in the pancreatic bed.

(Left) Axial NECT at presentation shows findings of acute interstitial pancreatitis, with infiltration of the peripancreatic fat planes and enlargement of the pancreas. (Right) Axial NECT after 9 days of IV fluid supplementation and bed rest shows the development of gas bubbles throughout the pancreatic parenchyma. At surgery, extensive infected necrosis of the pancreas was found and a necrosectomy was performed.

996

Acute Pancreatitis and Complications Pancreas

(Left) Axial NECT in a critically ill patient demonstrates necrosis of the entire pancreas and replacement by necrotic debris and gas bubbles compatible with infected necrosis. The patient in this case died as a result of his illness. (Right) Axial CECT image demonstrates a highattenuation pseudoaneurysm with surrounding hemorrhage in a patient who suffered a lifethreatening bleed from a ruptured pseudoaneurysm of the splenic artery resulting from pancreatitis.

(Left) Axial CECT demonstrates a large enhancing pseudoaneurysm arising within a hemorrhagic pseudocyst in a patient with acute pancreatitis. (Right) Axial CECT demonstrates a large well-defined, loculated fluid collection several months after a bout of acute edematous pancreatitis. Notice that the collection is simple in appearance without debris or hemorrhage, compatible with a pseudocyst. The large size and mass effect of this pseudocyst necessitated drainage.

(Left) Axial CECT performed several months after a bout of pancreatitis demonstrates a large, relatively simpleappearing loculated collection , with a well-defined wall, occupying the pancreatic bed. (Right) Axial T2 MR in the same patient demonstrates that the collection is actually not simple, but contains significant internal solid debris , suggesting this represents walled-off necrosis rather than a pseudocyst. Walled-off necrosis, unlike a pseudocyst, often requires either a large bore catheter for drainage, or necrosectomy.

997

Pancreas

Acute Pancreatitis and Complications

(Left) Coronal volumerendered CECT in a patient several weeks after a bout of necrotizing pancreatitis demonstrates a thick-walled fluid collection replacing a portion of the pancreatic head, compatible with walledoff necrosis. (Right) Axial T2 MR demonstrates a large chronic post pancreatitis fluid collection. The debris within the collection suggests that this is walled-off necrosis, not a pseudocyst. Distinguishing these 2 entities is a major advantage of MR compared to CT.

(Left) Axial CECT demonstrates a loculated fluid collection in the lesser sac with a well-defined wall and simple internal contents after a bout of pancreatitis, in keeping with a pseudocyst. An internal drain has been placed due to this pseudocyst's mass effect on the stomach. (Right) Axial CECT shows walled-off necrosis in the body of the pancreas with absence of normally enhancing pancreatic parenchyma in this location. The location of necrosis in this case raises concern for "disconnected duct" syndrome.

(Left) Axial T2-weighted MR demonstrates complex fluid that contains internal debris representing fat necrosis and hemorrhage. Note the extension of the fluid into the interfascial retroperitoneal space between the perirenal and anterior pararenal spaces and into the muscles of the flank. (Right) Coronal MRCP in the same patient shows multiple distal common duct stones as the cause of the patient's acute pancreatitis. Emergent ERCP was performed to remove the common duct stones.

998

Acute Pancreatitis and Complications Pancreas

(Left) Axial CECT shows heterogeneous enlargement and diminished enhancement of the pancreas , consistent with severe acute necrotizing pancreatitis. (Right) Axial CECT in the same patient 4 weeks later shows the development of walled-off necrosis with a well defined, peripherally enhancing wall. Note the multiple nondependent gas bubbles , indicating infection.

(Left) Axial CECT in a patient with abdominal pain and elevated lipase shows multiple low-density hepatic lesions , consistent with metastases. Note also the lesser sac fluid collection from acute pancreatitis. (Right) Axial CECT at more caudal level in the same patient shows upstream dilatation of the main pancreatic duct . Note that the pancreatic duct is obstructed by an isodense mass . Endoscopic ultrasound biopsy of the mass revealed adenocarcinoma, which presented as pancreatitis.

(Left) Axial CECT demonstrates enlargement of the pancreas with peripancreatic edema and stranding compatible with acute pancreatitis. Note, however, the dilated pancreatic duct , an unusual feature for acute pancreatitis. (Right) Coronal CECT in the same patient demonstrates a hypodense pancreatic adenocarcinoma obstructing the pancreatic duct . The presence of a dilated pancreatic duct in acute pancreatitis should always prompt search for an underlying mass.

999

Pancreas

Chronic Pancreatitis KEY FACTS

TERMINOLOGY • Progressive, irreversible inflammatory damage to pancreas resulting in parenchymal fibrosis, morphologic changes, and loss of endocrine/exocrine function

IMAGING • CT: Dilated, irregular pancreatic duct with strictures ○ Pancreatic parenchymal and intraductal calcification virtually diagnostic of chronic pancreatitis ○ Pancreatic atrophy (often more apparent in body/tail) ○ Fibroinflammatory "mass" related to chronic pancreatitis may be very difficult to differentiate from malignancy • MR: More sensitive for early changes compared to CT ○ Loss of normal high T1WI signal of parenchyma ○ parenchymal enhancement on T1WI C+ arterial phase ○ Dilated (> 3 mm), irregular pancreatic duct with strictures and dilated side branches ("chain of lakes" appearance) ○ Stones within pancreatic duct appear as signal voids ○ Secretin MRCP may identify earliest signs of CP

(Left) Ultrasound image demonstrates multiple large, coarse calcifications in the pancreatic head, some of which demonstrate posterior acoustic shadowing, compatible with chronic pancreatitis. (Right) Coronal MRCP demonstrates a dilated main pancreatic duct with dilated side branch ducts , as well as a distal pancreatic duct stricture . Chronic pancreatitis is a scirrhous process that commonly causes stricture or occlusion of the ducts.

(Left) Coronal MRCP MIP reconstruction demonstrates characteristic changes of "big duct" chronic pancreatitis, including a dilated main pancreatic duct with dilatation of multiple side branches, stricture in the downstream duct, and a large pseudocyst near the pancreatic tail. (Right) Axial CECT demonstrates extensive parenchymal calcifications throughout the pancreas in a patient with known chronic pancreatitis. The multiple cysts scattered throughout the pancreas in this case represent small pseudocysts.

1000

– Loss of normal duct distension (due to duct compliance) after secretin administration – Secretin may improve visualization of side branches – secretion of fluid into duodenum suggests pancreatic exocrine dysfunction

PATHOLOGY • Most commonly caused by alcohol abuse (~ 75% of cases) • Other causes include idiopathic, hereditary pancreatitis, autoimmune pancreatitis, and systemic diseases • Gallstones, hyperlipidemia, trauma, and drugs often cause acute/recurrent pancreatitis, but rarely chronic pancreatitis

CLINICAL ISSUES • Endocrine and exocrine deficiencies due to progressive destruction of gland may lead to steatorrhea and diabetes • Most patients treated with pain management, lifestyle modification (cessation of alcohol and smoking, frequent small meals), and pancreatic enzyme replacement • Surgery an option in patients who fail medical therapy

Chronic Pancreatitis

Definitions • Progressive, irreversible inflammatory damage to pancreas resulting in parenchymal fibrosis, morphologic changes, and loss of endocrine/exocrine function

IMAGING General Features • Best diagnostic clue ○ Atrophic pancreatic parenchyma with a dilated, beaded main pancreatic duct (MPD) and intraductal calculi

CT Findings • Earliest stages may not produce visible changes, but morphologic abnormalities more apparent in later stages ○ Dilated, beaded, irregular pancreatic duct with strictures ○ Pancreatic parenchymal and intraductal calcification virtually diagnostic of chronic pancreatitis (CP) ○ Pancreatic atrophy (often more apparent in body/tail) ○ Intra- and peripancreatic pseudocysts • Splenic vein often thrombosed with resultant varices and splenomegaly • Fibroinflammatory "mass" related to chronic pancreatitis may be very difficult to differentiate from malignancy ○ Most common in pancreatic head and may demonstrate variable enhancement – Hypoenhancing mass usually due to fibrosis, whereas isodense mass implies lack of fibrosis

MR Findings • Normal MR appearance of pancreas ○ Parenchyma diffusely high signal on T1WI ( liver) ○ Parenchyma variable in signal on T2WI ○ Pancreas enhances avidly and homogeneously on T1W C+ images (hyperintense to liver on arterial phase and isointense on delayed phase) ○ Normal pancreatic duct measures < 3 mm and side branches are not normally visualized • More sensitive for early changes of chronic pancreatitis compared to CT (although less sensitive for calcifications) ○ Loss of normal high T1WI signal of parenchyma (due to fibrosis replacing parenchymal proteinaceous fluid) ○ Diminished parenchymal enhancement on T1W C+ images on arterial phase with increased delayed enhancement due to fibrosis • Changes in pancreatic duct (usually later finding) nicely demonstrated on T2WI or MRCP ○ Dilated (> 3 mm), irregular pancreatic duct with strictures and dilated side branches ("chain of lakes" appearance) ○ Visualization of side branches, which are not normally visible, may be subtle sign ○ Stones within pancreatic duct appear as signal voids ○ Cambridge criteria for ERCP may be applied to MRCP • Pancreatic atrophy and pseudocysts in later stages • Secretin MRCP can help visualize earliest findings of chronic pancreatitis and evaluate pancreatic exocrine dysfunction ○ Loss of normal duct distension (due to duct compliance) after secretin administration in CP – Normal duct dilates 1 mm compared to baseline (< 1 mm distension suggests CP)

○ Secretin may improve visualization of side branches (finding that suggests CP) ○ secretion of fluid into duodenum suggests pancreatic exocrine dysfunction, suggesting CP – Grade I: Fluid seen in duodenal bulb (most suggestive of pancreatic exocrine dysfunction) – Grade II: Fluid seen in 2nd portion of duodenum – Grade III: Fluid reaches 3rd portion of duodenum • MR, like CT, cannot reliably distinguish fibroinflammatory mass (due to CP) from malignancy

Pancreas

TERMINOLOGY

Radiographic Findings • Radiography ○ Abdominal radiographs: May demonstrate small, irregular, or coarse calcifications (local or diffuse) in expected location of pancreas in upper abdomen ○ Upper GI series: May reveal changes in 2nd part of duodenum – Thickened, irregular mucosal folds, luminal narrowing, and varying degrees of atony with dilatation of proximal duodenum ± stomach • ERCP ○ Considered gold standard test for chronic pancreatitis ○ Dilated, irregular, and beaded main pancreatic duct with sites of stricture and dilated side branches ○ Intraductal calculi appear as filling defects within MPD ○ Intrapancreatic portion of CBD may be narrowed, but demonstrates smooth, tapered narrowing (not abrupt narrowing as with malignancy) – May produce double duct sign due to stricture of distal CBD and MPD (similar to malignancy) ○ Cambridge criteria for chronic pancreatitis on ERCP – Normal: Normal MPD and side branches – Equivocal: Normal MPD with < 3 abnormal side branches – Mild: Normal MPD with 3 abnormal side branches – Moderate: Abnormal MPD and 3 abnormal side branches – Severe: Abnormal MPD with large cavity (> 10 mm), ductal obstruction, filling defects, or severe dilatation/irregularity and 3 abnormal side branches

Ultrasonographic Findings • Grayscale ultrasound ○ Dilated MPD (± CBD) with echogenic parenchymal and ductal calcifications (with posterior acoustic shadowing) ○ Gland may appear hypoechoic and heterogeneous • Endoscopic ultrasound ○ Multiple criteria for diagnosis including parenchymal abnormalities (hyperechoic foci, hyperechoic strands, lobulated parenchymal contour, cysts) and ductal abnormalities (dilated MPD, irregular MPD, hyperechoic duct walls, visible side branches, calcifications)

Imaging Recommendations • MR/MRCP (with secretin) is best noninvasive imaging test • Endoscopic ultrasound may be helpful for early-stage disease and ERCP utilized primarily for intervention (stone extraction, stent, etc.)

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Pancreas

Chronic Pancreatitis

DIFFERENTIAL DIAGNOSIS

CLINICAL ISSUES

Pancreatic Ductal Carcinoma

Presentation

• Poorly marginated hypoenhancing mass with upstream parenchymal atrophy and abrupt obstruction of MPD/CBD • Posterior extension into retroperitoneum with encasement and narrowing of mesenteric vasculature • Some cases of fibroinflammatory mass due to chronic pancreatitis and pancreatic cancer are impossible to differentiate without surgical resection and histology

• Most common signs/symptoms ○ Recurrent or chronic midepigastric pain (typically radiates to back and is worse after eating) ○ Endocrine and exocrine deficiencies due to progressive destruction of gland and stricture of CBD: Steatorrhea, diabetes mellitus, and jaundice – Morphologic changes on imaging correlate with endocrine/exocrine dysfunction □ "Big" duct disease with gross abnormalities of MPD often results in steatorrhea and diabetes □ "Small" duct disease with normal MPD and relatively normal-appearing pancreas unlikely to produce steatorrhea and diabetes • Lab data ○ Amylase and lipase not reliable for CP, as they may be normal or only minimally elevated

Pancreatic Intraductal Papillary Mucinous Neoplasm (IPMN) • Involvement of main pancreatic duct may simulate chronic pancreatitis clinically and on CT/MR • Dilated MPD (± side branches) with parenchymal atrophy • ERCP can more easily make distinction with ability to visualize mucus ± polypoid lesions within MPD

Senescent Change • Pancreatic parenchyma atrophies with age (usually > 70 years), duct may mildly dilate, and parenchyma may demonstrate small foci of calcification • MR may demonstrate parenchymal enhancement and T1WI signal in age-related fibrosis (like chronic pancreatitis) • Degree of ductal dilatation usually quite mild without irregularity, strictures, or intraductal stones

Demographics • Age ○ Usually middle-aged adults ○ Hereditary pancreatitis may present < 20 years • Gender ○ M>F

Natural History & Prognosis

PATHOLOGY General Features • Etiology ○ Chronic pancreatitis most commonly caused by alcohol abuse (~ 75% of cases in USA) – Persistent, heavy alcohol consumption for > 10 years usually required to develop chronic pancreatitis – Other causes include idiopathic (10-30% of cases), hereditary pancreatitis, tropical pancreatitis, autoimmune pancreatitis, and systemic diseases (most notably cystic fibrosis) – Obstructive chronic pancreatitis due to narrowing/stricture of duct □ Includes congenital abnormalities that predispose to CP, including pancreas divisum, annular pancreas, and sphincter of Oddi dysfunction – Toxins (tobacco) may play causative role ○ Gallstones, hyperlipidemia, trauma, and drugs often cause acute/recurrent pancreatitis, but rarely CP ○ Pathogenesis still debated but probably due to chronic reflux of pancreatic enzymes, bile, and duodenal contents with increased ductal pressure – Resultant activation of pancreatic stellate cells by toxins sets up fibroinflammatory response • Genetics ○ Hereditary pancreatitis may be related to several genes, including PRSS1-cationic trypsinogen, SPINK1-trypsin inhibitor, and CFTR – Most commonly autosomal dominant trait with incomplete penetrance ○ Genetic predisposition toward pancreatitis related to alcohol: Some patients suffer irreversible injury with modest ingestion of alcohol 1002

• Complications ○ Jaundice due to biliary obstruction ○ Duodenal obstruction ○ Significant in pancreatic cancer incidence

Treatment • Most patients treated with pain management, lifestyle modification (cessation of alcohol and smoking, frequent small meals), and pancreatic enzyme replacement • Surgery an option in patients who fail medical therapy ○ Patients with "big" duct disease and a grossly dilated duct may undergo surgical decompression of duct (usually anastomosis of duct with Roux limb) ○ Surgical resection (Whipple procedure, distal pancreatectomy, total pancreatectomy) is an option in patients with "small" duct disease

DIAGNOSTIC CHECKLIST Consider • Differentiate from other causes of MPD dilatation and glandular atrophy, including main duct IPMN and pancreatic adenocarcinoma • Fibroinflammatory mass related to chronic pancreatitis may be very difficult to distinguish from pancreatic adenocarcinoma

SELECTED REFERENCES 1.

Gupte AR et al: Chronic pancreatitis. Curr Opin Gastroenterol. 30(5):500-5, 2014

Chronic Pancreatitis Pancreas

(Left) Axial CECT in a patient with chronic pancreatitis demonstrates an infiltrative hypodense pancreatic mass , with a dilated upstream pancreatic duct . A few calcifications were present in the parenchyma (not shown). The patient underwent Whipple procedure due to concern for malignancy, where this was found to be a fibroinflammatory mass related to chronic pancreatitis. (Right) ERCP shows irregular dilatation of the main pancreatic duct and side branches characteristic of chronic pancreatitis.

(Left) Coronal MRCP MIP reconstruction in a patient with chronic abdominal pain demonstrates subtle dilatation of a few scattered pancreatic duct side branches . Side branch dilatation can be an early sign of chronic pancreatitis, subsequently confirmed in this patient using endoscopic ultrasound. (Right) Axial CECT shows a large, discrete stone within a dilated main pancreatic duct in a patient with known alcohol-related chronic pancreatitis. The duct itself appears subtly irregular and beaded.

(Left) Coronal curved planar reformation from a CECT shows dilatation of the pancreatic duct upstream from a stricture in the head of the pancreas. Note the dilated side branches of the pancreatic duct and extensive parenchymal calcifications , diagnostic of chronic pancreatitis. (Right) Axial MIP image from a CECT in the same patient illustrates extensive parenchymal calcifications . This patient required enzyme replacement therapy due to exocrine insufficiency.

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Pancreas

Groove Pancreatitis KEY FACTS

TERMINOLOGY • Form of chronic pancreatitis affecting pancreaticoduodenal groove ○ Pure form: Affects only pancreaticoduodenal groove ○ Segmental form: Affects pancreaticoduodenal groove and extends medially into pancreatic head • Pancreatic groove is a theoretical space defined by pancreatic head (medially), 2nd portion of duodenum (laterally), 3rd portion of duodenum and IVC (posteriorly), and duodenal bulb (superiorly)

IMAGING • Sheet-like, curvilinear soft tissue mass between pancreatic head and duodenum ○ May demonstrate delayed enhancement ○ MR: Usually T1 hypointense with variable T2 signal (depending on acuity) • Thickened medial duodenal wall ± cysts within groove or thickened duodenal wall

(Left) Gross photo of a pancreaticoduodenectomy specimen shows a mass-like lesion beneath the duodenal mucosa, representing groove pancreatitis. Note the paraduodenal zone of fibrosis with numerous small cysts . (Right) Axial CECT shows subtle soft tissue thickening in the pancreaticoduodenal groove, as well as mass-like pancreatic head enlargement with an internal cyst . This was found to be segmental (given pancreatic head involvement) groove pancreatitis at surgery.

(Left) Axial CECT image demonstrates a hypodense soft tissue mass in the pancreaticoduodenal groove with associated cystic spaces , resulting in upstream pancreatic ductal dilatation . (Right) Coronal volumerendered CECT image nicely demonstrates the hypodense soft tissue in the pancreaticoduodenal groove with associated cystic spaces . Initially suspected to represent malignancy, this was found to be groove pancreatitis at surgery.

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• Segmental form: Mass-like enlargement of pancreatic head • Calcifications and ductal dilatation/beading can develop in chronic setting (similar to traditional chronic pancreatitis)

TOP DIFFERENTIAL DIAGNOSES • Pancreatic ductal adenocarcinoma • Duodenal carcinoma • Acute edematous pancreatitis involving groove

CLINICAL ISSUES • Usually middle-aged men with history of alcohol abuse • Acute setting: Postprandial abdominal pain, vomiting, or acute gastric outlet obstruction • Chronic setting: Chronic weight loss, jaundice • Amylase, lipase, and tumor markers are usually normal • Prospective diagnosis is very uncommon; difficult to exclude malignancy with imaging or biopsy • Surgery (Whipple procedure) may be required to rule out malignancy or due to intractable symptoms

Groove Pancreatitis

Synonyms • Cystic dystrophy of duodenal wall, pancreatic hamartoma of duodenal wall, periampullary duodenal wall cyst

Definitions • Form of chronic pancreatitis affecting pancreaticoduodenal groove ○ Pure form: Affects only pancreaticoduodenal groove ○ Segmental form: Affects pancreaticoduodenal groove and extends medially into pancreatic head • Pancreatic groove is a theoretical space defined by pancreatic head (medially), 2nd portion of duodenum (laterally), 3rd portion of duodenum and IVC (posteriorly), and duodenal bulb (superiorly) ○ Contains distal common bile duct (CBD), main/accessory pancreatic ducts, and major/minor papilla

IMAGING General Features • Best diagnostic clue ○ Curvilinear soft tissue between pancreas and duodenum

CT Findings • Sheet-like, curvilinear soft tissue mass (with delayed enhancement) between pancreatic head and duodenum • Thickened medial duodenal wall ± cysts (within pancreatic groove, duodenal wall, or pancreatic head) • Narrowing of distal CBD and pancreatic duct at ampulla • Absence of retroperitoneal inflammation or fluid • Segmental form: Mass-like enlargement of pancreatic head • Calcifications and ductal beading in chronic setting

MR Findings • Sheet-like groove thickening is mildly T1 hypointense • Variable T2 signal (depending on acuity): T2 hyperintense in acute phase and hypointense chronically ○ T2 hyperintense cysts in medial duodenal wall or groove • Pancreatic head may be enlarged with low T1 signal in segmental form (due to fibrosis/atrophy) • T1WI C+: Delayed enhancement of affected areas • MRCP: Smooth narrowing of distal CBD and pancreatic duct with widened space between ampulla and duodenal lumen

Ultrasonographic Findings • Acute setting: Hypoechoic band-like thickening in groove (with hypoechoic, heterogeneous pancreatic head in segmental form) • Chronic setting: Hyperechoic band-like thickening in groove (with hyperechoic pancreatic head in segmental form)

Imaging Recommendations • Best imaging tool ○ CECT or MR with MRCP

DIFFERENTIAL DIAGNOSIS Pancreatic Ductal Adenocarcinoma • Infiltrative hypodense mass with upstream pancreatic atrophy and pancreatic ductal dilatation

• May be centered in close proximity to groove and appear indistinguishable from groove pancreatitis • Thickening of duodenal wall or cystic change is uncommon

Pancreas

TERMINOLOGY

Duodenal Carcinoma • Mass centered in duodenum (not in pancreatic groove) without cystic change

Acute Edematous Pancreatitis Involving Groove • Not primarily centered in pancreaticoduodenal groove and usually involves entire pancreas • Associated with peripancreatic inflammation, including retroperitoneal fluid and fat stranding • Should resolve on follow-up examinations

PATHOLOGY General Features • Etiology ○ Exact cause unknown, although there are multiple theories – Alcohol consumption or smoking increased viscosity of pancreatic juice occlusion of minor papilla – Functional obstruction of minor papilla/Santorini duct – Heterotopic pancreas in duodenal wall – Peptic ulcer disease and Brunner gland hyperplasia

Gross Pathologic & Surgical Features • Fibrotic mass-like thickening in pancreaticoduodenal groove and stenosis of terminal CBD • Involved areas can have internal cysts (± internal calculi)

Microscopic Features • Brunner gland and smooth muscle hyperplasia • Chronic pancreatitis ± calcification

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Acute setting: Postprandial abdominal pain, nausea, and vomiting ○ Chronic setting: Chronic weight loss, jaundice ○ Amylase, lipase, and tumor markers usually normal

Demographics • Often middle-aged men with history of alcohol abuse

Natural History & Prognosis • May progress to generalized chronic pancreatitis

Treatment • Prospective diagnosis is very uncommon; difficult (or impossible) to exclude malignancy with imaging or biopsy • Surgery (Whipple procedure) may be required to rule out malignancy or due to intractable symptoms • Fasting, parenteral nutrition, and cessation of smoking/alcohol if prospective diagnosis is made

SELECTED REFERENCES 1.

Raman SP et al: Groove pancreatitis: spectrum of imaging findings and radiology-pathology correlation. AJR Am J Roentgenol. 201(1):W29-39, 2013

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Pancreas

Groove Pancreatitis

(Left) Axial CECT demonstrates subtle stranding and induration in the pancreaticoduodenal groove, which persisted on follow-up examinations. (Right) Axial CECT image from the same patient again demonstrates induration in the pancreaticoduodenal groove. Initially suspected to represent a duodenal malignancy, this was found to be groove pancreatitis at surgery.

(Left) Axial CECT shows focal soft tissue thickening in the pancreaticoduodenal groove, which persisted over multiple follow-up studies. There is also some fluid tracking from the groove into the right anterior pararenal space. (Right) Axial CECT in the same patient shows thickening in the groove, with several cysts present in the pancreatic head. This was found to be groove pancreatitis at surgery, but the presence of fluid tracking in the retroperitoneum is atypical and more common with acute edematous pancreatitis.

(Left) Axial CECT demonstrates focal soft tissue thickening in the pancreaticoduodenal groove with multiple internal cystic spaces . (Right) Coronal volume-rendered CECT from the same patient again demonstrates focal soft tissue thickening in the pancreaticoduodenal groove with multiple internal cystic spaces . While this was suspected to represent groove pancreatitis, Whipple procedure was performed to exclude underlying malignancy, a common outcome in these cases.

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Groove Pancreatitis Pancreas

(Left) Axial CECT shows a markedly distended stomach and proximal duodenum secondary to gastric outlet obstruction. Note the bandlike soft tissue thickening in the groove between the 2nd duodenum and the pancreas, characteristic of groove pancreatitis. (Right) More caudal CECT from the same patient shows that the lumen of the 2nd portion of duodenum is markedly narrowed by the adjacent soft tissue, and there is a small cyst in the pancreatic groove.

(Left) Axial CECT shows thickening of the medial wall of the duodenum, luminal narrowing, and 2 small cysts . This was found to represent groove pancreatitis at surgery. (Right) Axial CECT image demonstrates a fibroinflammatory mass with calcifications centered in the groove. Groove pancreatitis in the chronic setting, as in this case, can appear very similar to traditional chronic pancreatitis (including the presence of calcifications).

(Left) Axial CECT shows lowattenuation soft tissue thickening in the groove between the head of the pancreas and the 2nd duodenum . Note the stent in the common duct placed due to biliary obstruction from the adjacent soft tissue. (Right) Axial volume-rendered CECT shows that the hypodense soft tissue encases the gastroduodenal artery and thickens the medial wall of the 2nd duodenum .

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Pancreas

Autoimmune (IgG4) Pancreatitis KEY FACTS

TERMINOLOGY • Immune-mediated fibroinflammatory disease primarily involving pancreas responding to steroid therapy

IMAGING • Diffuse form ○ Sausage-like enlargement of pancreas (with smooth contour) and loss of normal pancreatic lobulations ○ Hypoattenuating halo or capsule around pancreas ○ Absence of retroperitoneal fluid, fluid collections/pseudocysts, or inflammation ○ Less enhancement than expected in arterial phase; parenchyma/capsule may show delayed enhancement ○ Diffuse or segmental narrowing of pancreatic duct ○ MRCP: Multiple discontiguous MPD/bile duct strictures which resolve after secretin (duct penetrating sign) • Focal form ○ Focal mass or localized enlargement of pancreas (usually head/uncinate) with delayed enhancement

(Left) Axial CECT shows diffuse infiltration and enlargement of the pancreas with loss of normal fatty lobulation. There is a hypodense halo or capsule around the pancreas, with relatively little spread into adjacent tissues, compatible with autoimmune pancreatitis. All symptoms and signs resolved with steroid therapy. (Right) Transhepatic cholangiogram in a patient with autoimmune pancreatitis shows multifocal strictures indistinguishable from those of primary sclerosing cholangitis.

(Left) Axial CECT demonstrates a diffusely enlarged pancreas with a low attenuation halo around its margin. (Right) Coronal CECT from the same patient shows similar findings with a low attenuation capsule around the enlarged pancreatic margin. Note the presence of biliary dilatation in this patient with a history of biliary strictures, often associated with autoimmune pancreatitis.

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○ Lack of biliary or pancreatic ductal dilatation

TOP DIFFERENTIAL DIAGNOSES • Pancreatic ductal adenocarcinoma • Chronic pancreatitis • Acute edematous pancreatitis

PATHOLOGY • Two distinct histologic subtypes ○ Type I: Lymphoplasmacytic sclerosing pancreatitis – Positive IgG4 tissue staining; serum IgG4 elevated – Extrapancreatic organ involvement common (~ 60%); inflammatory bowel disease in only 2-6% – Older patients (usually > age 60) with M > F ○ Type II: Idiopathic duct-centric pancreatitis – No IgG4 tissue staining; serum IgG4 not elevated – No extrapancreatic organ involvement; inflammatory bowel disease in 30% – Younger patients (mean age 43) with M=F

Autoimmune (IgG4) Pancreatitis

DIFFERENTIAL DIAGNOSIS

Abbreviations

Pancreatic Ductal Carcinoma

• Autoimmune pancreatitis (AIP)

• Focal AIP difficult to differentiate from pancreatic cancer • Upstream MPD dilatation and glandular atrophy (unlike AIP)

Definitions • Immune-mediated fibroinflammatory disease primarily involving pancreas responding to steroid therapy

IMAGING

Chronic Pancreatitis • Atrophic gland with beaded, dilated pancreatic duct and parenchymal/intraductal calcifications • History of alcoholism and pain symptoms (unlike AIP)

General Features

Acute Edematous Pancreatitis

• Best diagnostic clue ○ Diffusely/focally enlarged pancreas with hypodense halo • Location ○ May be diffuse, multifocal, or focal/mass-forming

• Enlarged, inflamed pancreas with retroperitoneal fluid and inflammation (uncommon in AIP)

CT Findings

General Features

• Diffuse form ○ Diffuse sausage-like enlargement of pancreas (with smooth contour) and loss of pancreatic lobulations ○ Hypoattenuating halo or capsule around pancreas ○ Often less enhancement than expected in arterial phase; delayed enhancement of involved parenchyma/capsule ○ No retroperitoneal fluid collections or inflammation • Focal form ○ Focal mass or localized enlargement of pancreas (usually head/uncinate) with delayed enhancement • Diffuse or segmental narrowing of pancreatic duct • Extrapancreatic imaging findings ○ IgG4 cholangitis in 90%: May be indistinguishable from primary sclerosing cholangitis ○ Renal involvement in 35% of patients with AIP – Round or wedge-shaped low attenuation parenchymal lesions ○ Retroperitoneal fibrosis, IgG4-related lung disease, and enlarged salivary glands or salivary gland mass

• Etiology ○ Exact pathogenesis unknown, but autoimmune etiology likely given steroid response/elevated antibody titers

MR Findings • Diffuse enlargement of pancreas (T1WI hypointense and T2WI hyperintense) • Capsule of peripheral hypoenhancement and low T2WI signal with delayed enhancement • MR cholangiopancreatography (MRCP): Multiple discontiguous main pancreatic duct/bile duct strictures ○ Strictures resolve after secretin (duct-penetrating sign) • DWI: Mildly restricted diffusion of affected tissue

PATHOLOGY

Staging, Grading, & Classification • Type I: Lymphoplasmacytic sclerosing pancreatitis ○ More common than Type II (80% of cases in US) ○ Older patients (usually > age 60) with M > F ○ Positive IgG4 tissue staining; serum IgG4 elevated ○ Extrapancreatic organs often involved (~60%) ○ Inflammatory bowel disease in 2-6% ○ Relapses after steroid therapy frequent (up to 40%) ○ Imaging: Diffuse (60%) or focal lesions (40%) • Type II: Idiopathic duct-centric pancreatitis ○ Younger patients (mean age 43); no M/F predominance ○ No IgG4 tissue staining; serum IgG4 normal ○ No extrapancreatic organ involvement; IBD in 30% ○ Rarely relapses after steroid therapy ○ Imaging: Focal pancreatic lesions (85%)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Type I AIP: Obstructive jaundice 75%, acute pancreatitis 15%, diabetes 85%, chronic abdominal pain, weight loss ○ Type II AIP: Obstructive jaundice 50%, acute pancreatitis 33%, abdominal pain ○ Much less pain than other forms of pancreatitis

Ultrasonographic Findings

Demographics

• Endoscopic ultrasound ○ Enlarged hypoechoic gland with sausage-like appearance, narrowed MPD, and thickening of CBD wall

• Epidemiology ○ 5-6% of chronic pancreatitis cases ○ No history of alcohol abuse, smoking, or biliary stones

Nuclear Medicine Findings

Natural History & Prognosis

• PET/CT ○ Diffuse uptake throughout pancreas (unlike malignancy) ○ Extrapancreatic uptake (salivary glands, kidneys) suggests AIP

• Slowly progresses to end-stage disease unless treated • Dramatic response to steroids, with immunomodulators utilized if steroid resistant

Other Modality Findings • ERCP: Diffuse or segmental narrowing (often with multiple discontinuous strictures) of main pancreatic duct (MPD)

Pancreas

TERMINOLOGY

SELECTED REFERENCES 1.

Khandelwal A et al: Recent advances in the diagnosis and management of autoimmune pancreatitis. AJR Am J Roentgenol. 202(5):1007-21, 2014

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Pancreas

Autoimmune (IgG4) Pancreatitis

(Left) Axial T1 C+ MR image in the arterial phase demonstrates diffuse pancreatic enlargement with a low signal rim or capsule around the margin of the pancreas. (Right) Axial T1 C+ MR in a more delayed phase demonstrates that the capsule now shows avid delayed enhancement, a characteristic feature of autoimmune pancreatitis.

(Left) Axial CECT shows a hypodense mass in the head of the pancreas mimicking a ductal adenocarcinoma . (Right) Coronal reformatted CECT in the same patient shows the focal mass in the pancreatic head, a tapered stricture of the common bile duct , and a normal pancreatic duct . Endoscopic ultrasound-guided biopsy of the pancreatic head mass revealed autoimmune pancreatitis. The lack of dilatation of the pancreatic duct was an important clue to the diagnosis.

(Left) Axial CECT shows diffuse enlargement and loss of fatty lobulation of the entire tail of the pancreas . The pancreatic duct in this segment is not identified and there is little surrounding inflammation. (Right) Axial CECT at a more caudal level in the same patient shows that the pancreas has a subtle surrounding low-attenuation halo , typical of autoimmune pancreatitis.

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Autoimmune (IgG4) Pancreatitis Pancreas

(Left) Initial axial CECT shows a focal hypodense mass in the tail of the pancreas. Serologic testing (IgG4) suggested the diagnosis of autoimmune pancreatitis and steroid therapy was started. (Right) Repeat axial CECT in the same patient 10 months later shows substantial decrease in size of the inflammatory mass and slight atrophy of the affected pancreatic tail segment.

(Left) Axial CECT demonstrates mild enlargement of the pancreas with a subtle low-density capsule in a patient with an elevated IgG4, compatible with autoimmune pancreatitis. Note the low-density wedgeshaped lesions in the left kidney. (Right) Coronal CECT in the same patient better demonstrates the full extent of the wedge-shaped low density lesions in both kidneys. Renal lesions, likely a manifestation of autoimmune disease, are a frequent associated finding in patients with AIP.

(Left) Axial CECT in a patient with chronic abdominal pain demonstrates an enlarged pancreas with a subtle lowattenuation capsule . This was thought to likely represent autoimmune pancreatitis, and the patient was found to have elevated IgG4. (Right) Axial CECT in the same patient following treatment with steroids demonstrates that the pancreas now appears normal in size with resolution of the previously seen lowattenuation halo.

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Pancreas

Pancreatic Lipomatous Pseudohypertrophy KEY FACTS

TERMINOLOGY

• Homogeneous, focal or diffuse enlargement of pancreas with fatty replacement of affected pancreatic parenchyma • No imaging or clinical signs of cystic fibrosis • Pancreas follows fat signal on all MR sequences

• Pancreatic focal fatty infiltration ○ Usually limited to head-uncinate or body-tail segments • Shwachman-Diamond syndrome ○ Rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and short stature • Retroperitoneal liposarcoma ○ Often confused with lipomatous pseudohypertrophy due to massive fatty hypertrophy in retroperitoneum

TOP DIFFERENTIAL DIAGNOSES

PATHOLOGY

• Cystic fibrosis ○ Pancreas appears identical to lipomatous pseudohypertrophy, but with very different clinical presentation • Pancreatic senescent changes ○ Pancreatic atrophy, but rarely clinically significant ○ Usually more uneven fatty replacement of pancreas ○ Also associated with obesity, diabetes, and steroid use

• Exact etiology is unknown • Possibly congenital, but may require inciting factor such as cirrhosis, viral infection, or abnormal metabolism

• Enlargement of pancreas due to replacement by adipose tissue with atrophy of normal exocrine parenchyma

IMAGING

(Left) Axial NECT in a woman with alcoholic cirrhosis shows typical cirrhotic morphology of the liver (nodular with widened fissures) and ascites. (Right) Axial NECT in the same patient shows diffuse enlargement and fatty replacement of the pancreas , which mimics findings seen in cystic fibrosis.

(Left) Axial T1WI C+ FS MR in the same patient shows the lipomatous pseudohypertrophy with diffuse dropout of signal throughout the body of the pancreas due to fat suppression. (Right) Axial opposed-phase T1WI in the same patient shows high signal throughout the pseudohypertrophied pancreas .

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CLINICAL ISSUES • Usually incidental finding on CT or in autopsy • Rarely, patients require enzyme therapy due to exocrine deficiency

Pancreatic Lipomatous Pseudohypertrophy

Definitions • Enlargement of pancreas due to replacement by adipose tissue with atrophy of normal exocrine parenchyma

IMAGING General Features • Best diagnostic clue ○ Diffuse enlargement and fatty replacement of pancreas ○ No imaging or clinical signs of cystic fibrosis • Location ○ Focal (tail, body, head) or diffuse involvement (more common) • Size ○ Usually 2-4x size of normal pancreas • Morphology ○ Homogeneous fatty replacement

Retroperitoneal Liposarcoma • Lipomatous pseudohypertrophy often confused with liposarcoma due to massive fatty hypertrophy in retroperitoneum and mass effect on adjacent structures

PATHOLOGY General Features • Etiology ○ Unknown ○ Possibly congenital, but may require inciting factor, such as cirrhosis, viral infection, or abnormal metabolism • Associated abnormalities ○ Chronic advanced liver disease, parkinsonism, COPD

Gross Pathologic & Surgical Features • Enlargement of pancreas with focal/diffuse fatty replacement of normal pancreatic tissue • No evidence of capsule

Imaging Recommendations

Microscopic Features

• Best imaging tool ○ CT or MR

• • • •

CT Findings • Homogeneous, focal or diffuse enlargement of pancreas with fatty replacement of affected pancreatic parenchyma ○ No imaging or clinical signs of cystic fibrosis • Usually no evidence of ductal obstruction (pancreatic or biliary) or discrete mass • Mass effect upon adjacent structures due to pancreatic enlargement is common

MR Findings • Appearance of pancreas follows fat signal on all sequences

DIFFERENTIAL DIAGNOSIS Cystic Fibrosis • Appearance of pancreas identical to lipomatous pseudohypertrophy • Patients with cystic fibrosis can develop cirrhosis • Unique clinical presentation, beginning in childhood ○ Chronic infections in lungs, failure to thrive, bowel obstruction, etc.

Pancreatic Senescent Changes • Age-related lipomatosis, fibrosis, and ductal epithelial alterations • Pancreatic atrophy, but rarely clinically evident or significant ○ Usually more uneven, heterogeneous fatty replacement of pancreas • Also associated with obesity, diabetes, and steroid use

Pancreatic Focal Fatty Infiltration • Normal-sized pancreas • Partial fatty replacement of acinar parenchyma • Often limited to either head-uncinate or body-tail segments ○ Corresponds to fetal ventral and dorsal segments

Pancreas

TERMINOLOGY

Marked atrophy and loss of exocrine glandular elements Replacement by mature adipose tissue Preservation of ducts and islets of Langerhans No evidence of fat necrosis or underlying pancreatitis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Asymptomatic ○ Can rarely result in pancreatic exocrine dysfunction • Other signs/symptoms ○ Mass effect (common), bile duct obstruction (rare)

Demographics • Epidemiology ○ Rare, with only a few sporadic reports in literature ○ No gender predominance ○ Usually young patients, but increasingly reported in older patients

Natural History & Prognosis • Very benign course • Usually incidental finding on CT or in autopsy • Rarely, patients require enzyme therapy due to exocrine deficiency

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Look for clinical or imaging evidence of cystic fibrosis as alternative diagnosis

SELECTED REFERENCES 1.

Izumi S et al: A minute pancreatic ductal adenocarcinoma with lipomatous pseudohypertrophy of the pancreas. JOP. 12(5):464-8, 2011

Shwachman-Diamond Syndrome • Rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and short stature 1013

Pancreas

Pancreatic Trauma KEY FACTS

IMAGING

PATHOLOGY

• CT ○ Secondary signs of pancreatic injury are usually present (peripancreatic fat stranding and fluid, thickening of pararenal fascia, peripancreatic hematoma) ○ Pancreatic contusion: Ill-defined focal hypoattenuation at site of injury (not linear like laceration) ○ Pancreatic laceration: Discrete linear hypodense cleft through pancreas ○ Pancreatic fracture: Large laceration with clear separation of 2 ends of gland ○ CT insensitive for pancreatic duct injury (usually inferred by laceration extending through duct) • MR: MRCP (± secretin) is a useful tool in determining presence of pancreatic ductal disruption • ERCP: Best modality for pancreatic ductal injury ○ Transection of pancreatic duct: Abrupt duct termination or contrast extravasation

• May result from either penetrating or blunt trauma ○ Blunt traumatic injury usually results from anterior/posterior compression force to abdomen • Pancreatic injuries almost never isolated and usually associated with polytrauma

(Left) Axial CECT shows subtle laceration of the pancreas with fluid in the lesser sac as well as retropancreatic fluid . (Right) Axial CECT in the same patient reveals fluid tracking posterior to the pancreas along the splenic vein from extravasated pancreatic juice. Secondary signs of injury, such as peripancreatic fluid, hematoma, or fat stranding, are almost always present as a clue to the diagnosis.

(Left) Axial CECT in a patient with pancreatic fracture shows a fracture plane through the neck of the pancreas. The pancreatic duct was disrupted, and the body and tail of the pancreas were resected at surgery. (Right) Axial CECT 48 hours after trauma shows a pseudocyst in the lesser sac in this pancreatic transection .The fluid collection developed as a result of leakage of fluid from the site of the transected pancreatic duct.

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CLINICAL ISSUES • Blunt pancreatic injuries often clinically occult and unrecognized on initial evaluation • Clinical presentation often due to traumatic pancreatitis: Upper abdominal pain, abdominal distention • Serum amylase/lipase levels: Elevated in 90% of patients, but may be normal immediately after trauma • Treatment: Penetrating trauma generally requires immediate laparotomy ○ AAST grades I and II: Conservative management ○ AAST grades III, IV, and V: Typically require surgery (including possible pancreatic resection)

Pancreatic Trauma

General Features • Best diagnostic clue ○ Enlarged, heterogeneous pancreas with peripancreatic fluid or hematoma in patient with history of trauma • Location ○ Most commonly involves pancreatic body > head > tail

Radiographic Findings • ERCP ○ Normal in cases of pancreatic contusion ○ Best modality to identify pancreatic duct (PD) injury – Transection of PD: Abrupt duct termination or contrast extravasation

CT Findings • Secondary signs of pancreatic injury or post-traumatic pancreatitis usually present even in absence of discrete contusion/laceration ○ Peripancreatic fat stranding and fluid with loss of normal peripancreatic fat planes almost always present – Fluid separating pancreas from splenic vein is sensitive (60-90%) for pancreatic injury – Fluid or hematoma is often seen in lesser sac, left anterior pararenal space, transverse mesocolon, adjacent to spleen, and mesenteric root ○ Thickening of anterior pararenal fascia ○ Peripancreatic or intrapancreatic hematoma: Intrapancreatic hematoma is more specific for pancreatic injury ○ Peripancreatic signs of traumatic pancreatitis are often subtle: May be more evident in 24-48 hours • Pancreatic contusion: Ill-defined focal hypoattenuation at site of injury ○ Appearance ranges from subtle contour deformity of pancreas to rounded mass-like enlargement of pancreas several cm in diameter ○ Often associated with focal or diffuse pancreatic enlargement • Pancreatic laceration: Discrete linear cleft of hypoattenuation running through pancreas (usually perpendicular to long-axis of gland) ○ Much more likely to be associated with PD injuries than contusion ○ Often associated with distortion or irregularity of contour of pancreas and hypoenhancement of gland upstream from laceration ○ Lacerations may produce subtle parenchymal density changes and may be undetectable on CT in some cases – 20-40% of pancreatic injuries not visible on initial imaging – May only be faintly visible on initial imaging, and become more conspicuous on follow-up imaging ○ CT is not sensitive for detection of PD injury (~ 40%): Inferred by presence of laceration extending through duct (> 50% of pancreatic thickness) • Pancreatic fracture: Linear low attenuation running through pancreatic parenchyma with clear separation of 2 ends of gland ○ Most often through pancreatic neck

MR Findings • Variably decreased signal on T1WI at sites of contusion or laceration ± high T1 signal related to hematoma • High signal on T2WI at sites of contusion or laceration • Heterogeneous enhancement on T1WI C+ images with areas of nonenhancement related to fluid collections, pseudocysts, necrosis, laceration, or severe contusion • MRCP useful tool to determine PD disruption ○ Secretin stimulation may improve diagnostic sensitivity ○ Ductal injury suggested by discontinuity in PD, along with direct communication to adjacent pseudocyst or fluid collection

Pancreas

IMAGING

Ultrasonographic Findings • Not sensitive for pancreatic injury or complications • Findings similar to pancreatitis (enlarged, hypoechoic gland)

Imaging Recommendations • Repeat CT at 24-48 hours may identify pancreatic injuries not appreciated on original examination

DIFFERENTIAL DIAGNOSIS Shock Pancreas • Part of hypoperfusion complex seen in severe traumatic injuries or in setting of severe hypotension • Abnormally intense enhancement of pancreas, bowel wall, and kidneys, with decreased caliber of aorta and inferior vena cava, and diffuse dilatation of intestine with fluid ○ Findings resolve spontaneously after fluid resuscitation • Pancreas appears edematous, enlarged, and hyperenhancing with surrounding fluid and fat stranding, mimicking post-traumatic pancreatitis or injury • Differentiate from direct traumatic injury by looking for other imaging features of hypoperfusion complex

Duodenal Injury Without Pancreatic Injury • Duodenal injury (including rupture or hematoma) may simulate or coexist with pancreatic injury • Duodenal hematoma appears as focal high-attenuation thickening of duodenal wall • Duodenal rupture results in gas or fluid tracking into anterior pararenal space ± oral contrast extravasation

Acute Pancreatitis • Pancreatic edema with peripancreatic fluid and stranding in lesser sac and anterior pararenal space ○ ± areas of nonenhancement in setting of necrosis • No history of trauma

PATHOLOGY General Features • Etiology ○ May result from either penetrating or blunt trauma – Penetrating injuries include gunshot wounds (45% of cases) and stab wounds (18% of cases) □ Pancreatic injuries in 20-30% of penetrating trauma – Mechanism in blunt trauma □ Most commonly the result of motor vehicle collisions, but also falls, crush injuries, and assaults (with direct blow to abdomen) 1015

Pancreas

Pancreatic Trauma □ Pancreatic injuries in children often due to blunt trauma, including trauma from bicycle handlebar, motor vehicle crash, or child abuse □ Usually result from anterior/posterior compression force to abdomen (more rarely lateral force vector) □ Pancreas is susceptible to injury, as it is relatively fixed anterior to spine and commonly compressed against vertebral column □ Lacerations to other structures usually accompany midline compression injury, including left hepatic lobe, duodenum, and central renal vascular pedicle • Associated abnormalities ○ Pancreatic injuries are almost never isolated and are usually associated with polytrauma ○ Duodenum (19-50% of cases) and liver (~ 20% of cases) frequently also injured ○ Vascular injuries also commonly associated (aorta, IVC, left renal vein, right renal artery)

Staging, Grading, & Classification • Grade of pancreatic injury independent predictor of pancreatic complications and mortality • American Association for Surgery in Trauma (AAST) grading system ○ Grade I: Minor contusion or superficial laceration (PD intact) ○ Grade II: Major contusion or deep laceration (PD intact) ○ Grade III: Distal laceration either with PD injury or complete transection of gland ○ Grade IV: Proximal (right of superior mesenteric artery) laceration or transection involving ampulla or bile duct ○ Grade V: Massive disruption of pancreatic head (usually requiring Whipple procedure) • CT grading system ○ Grade A: Superficial (< 50% of gland thickness) laceration or mild pancreatitis ○ Grade B: Deep (> 50% of gland thickness) or complete laceration of pancreatic tail ○ Grade C: Deep or complete laceration of pancreatic head

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ History of trauma (either blunt or penetrating) and multiple other traumatic injuries ○ Blunt pancreatic injuries not uncommonly clinically occult and unrecognized on initial evaluation ○ Presentation often reflects traumatic pancreatitis: Abdominal pain, postprandial vomiting, abdominal distention • Clinical profile ○ Serum amylase/lipase levels: Elevated in 90% of patients, but may be normal immediately after trauma – Not specific, as amylase levels may be elevated due to trauma to liver, duodenum, or salivary glands – Persistently rising amylase levels over time more specific (particularly 3 hours after injury) – Elevated amylase in diagnostic peritoneal lavage (DPL) fluid much more sensitive/specific than serum amylase 1016

Demographics • Gender ○ M>F • Epidemiology ○ Uncommon; 3-12% of all abdominal injuries – Acute post-traumatic pancreatitis represents only 0.4% of acute pancreatitis with pseudocyst formation – Incidence is much higher with penetrating injuries compared to blunt trauma ○ Accounts for 5% of all abdominal injuries in children and is most common cause of pseudocyst in children (often related to child abuse)

Natural History & Prognosis • Mortality from pancreatic injuries between 9-34% (only 5% due to pancreatic injury itself) ○ Most deaths occur within first 48 hours after trauma • Major complications occur in 50% of patients ○ Pancreatic fistula (11%), pancreatic pseudocyst (30%), pancreatitis (17%), intraabdominal abscesses (18%), associated liver or intestinal injuries (> 80%), abdominal hemorrhage, pseudoaneurysm • Subcutaneous fat necrosis/polyarthritis secondary to posttraumatic pancreatitis reported in < 1% of patients • Cerebral fat embolism: Rare possible complication of traumatic pancreatitis

Treatment • Penetrating trauma generally requires immediate laparotomy • AAST grades I and II (blunt trauma): Conservative nonoperative management ○ Superficial lesions not affecting PD can be managed nonoperatively ○ Total parenteral nutrition ± somatostatin or octreotide ○ Endoscopy with pancreatic stenting is increasingly common practice • AAST grades III, IV, and V (blunt trauma): Require surgery within 24 hours ○ Grade III: Usually distal pancreatectomy and splenectomy (with spleen preservation in children), although pancreas may be preserved with "clean" pancreatic lacerations ○ Grades IV and V: Pancreatic resection may be required, but approach is variable depending on concomitant duodenal and ampullary injuries – Surgical options include Whipple, extended distal pancreatectomy, central pancreatectomy, or surgical drainage

DIAGNOSTIC CHECKLIST Consider • Pancreatic injuries may be occult on initial imaging, but can become more evident after 24-48 hours • Thickening of anterior pararenal fascia on CT in trauma patient should prompt careful evaluation of pancreas

SELECTED REFERENCES 1.

Dreizin D et al: Evaluating blunt pancreatic trauma at whole body CT: current practices and future directions. Emerg Radiol. 20(6):517-27, 2013

Pancreatic Trauma Pancreas

(Left) Axial CECT shows a lowattenuation fracture plane traversing the mid body of the pancreas . Note the subtle retropancreatic fluid adjacent to the splenic vein. (Right) Axial CECT in the same patient at a more caudal level again shows the fracture plane and more obvious adjacent peripancreatic fluid . In some patients, retropancreatic fluid is the most conspicuous sign of a pancreatic fracture.

(Left) Axial CECT 24 hours after blunt trauma reveals ischemic necrosis in the body of the pancreas along the fracture plane and a perirenal fluid collection . (Right) Axial CECT in the same patient shows a subtle fracture of the head of the pancreas with fluid in the pancreatic groove . Note the adjacent shock bowel , which is thickened and hyperenhancing.

(Left) Axial CECT in a trauma patient demonstrates a focal hematoma at the pancreatic head/neck junction anteriorly , in keeping with this patient's pancreatic contusion. No discrete laceration was visualized. (Right) Axial CECT shows fluid surrounding the pancreas . While no parenchyma laceration was detected by CT, the isolated peripancreatic fluid, particularly in the presence of elevated serum lipase and amylase, is highly suggestive of a pancreatic injury.

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Pancreas

Postoperative Pancreas KEY FACTS

IMAGING • Normal findings immediately after Whipple procedure ○ Small free fluid, edema, and fat stranding in surgical bed with reactive subcentimeter lymph nodes in mesentery ○ Mild biliary dilatation, gastrojejunostomy thickening, and pancreatic duct dilatation due to anastomotic edema • Common complications ○ Pancreatic fistula: Leakage of amylase-rich fluid from pancreatic duct – Focal fluid collection, ectopic gas, or hematoma directly adjacent to pancreaticojejunostomy ○ Abscess: Can be intrahepatic, in pancreatic bed, or in subphrenic, subhepatic, or retroperitoneal spaces ○ Gastrojejunostomy and hepaticojejunostomy leaks: Suspect when focal fluid collection or ectopic gas in close contiguity to anastomosis ○ Postoperative pancreatitis: Fluid, edema, and stranding centered in pancreatic remnant

(Left) Graphic shows the Whipple (pancreaticoduodenectomy) procedure. Note the common bile duct margin , the pancreatic margin , and the intestinal margins . (Right) This graphic depicts Whipple anatomy: Pancreaticojejunostomy , choledochojejunostomy , gastrojejunostomy or duodenojejunostomy , and cholecystectomy . The pylorus may be removed or preserved, depending on extent of disease and surgeon preference. Note the ligated gastroduodenal artery .

(Left) Axial CECT demonstrates a collection of fluid and gas immediately adjacent to the pancreaticojejunostomy in a patient with an elevated drain amylase, compatible with pancreatic fistula. Note the presence of a pancreatic duct stent . (Right) Axial CECT in a patient with a fever after Whipple procedure demonstrates a thick-walled fluid collection in the right liver lobe with an internal airfluid level, compatible with a postoperative hepatic abscess.

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○ Liver infarct: Wedge-shaped areas of hypodensity at periphery of liver ○ Postoperative hemorrhage: May be due to bleeding from gastroduodenal artery stump or due to structural abnormality (e.g., pseudoaneurysm) ○ Portomesenteric venous thrombosis ○ Anastomotic strictures: Suspect when progressive biliary or pancreatic ductal dilatation without obstructing tumor at anastomotic site ○ Delayed gastric emptying: Gastric remnant markedly dilated with large retained ingested material and fluid ○ Tumor recurrence: Differentiate linear postoperative scarring from nodular, mass-like tumor recurrence

CLINICAL ISSUES • Whipple procedure mortality has dramatically fallen (was once ~ 25%, and is now 1-3%) • Morbidity for Whipple procedure remains considerable, with complications in ~ 20% of patients

Postoperative Pancreas

General Features • Surgical procedure determined by location and type of pathology ○ Whipple procedure most commonly performed for tumors of pancreatic head, uncinate, and proximal neck – Classic Whipple procedure (pancreaticoduodenectomy) involves surgical removal of pancreatic head, gastric antrum, proximal duodenum, and gallbladder – Pylorus-sparing Whipple procedure, which may theoretically have lower risk of bile reflux, retains pylorus and short segment of duodenum with creation of duodenojejunostomy – 3 anastomoses created: Hepaticojejunostomy, pancreaticojejunostomy, and gastrojejunostomy (classic) or duodenojejunostomy (pylorus-sparing) ○ Distal pancreatectomy performed for tumors of distal pancreatic neck, body, and tail – May be performed with splenectomy – Can be performed with en bloc celiac axis resection for some pancreatic body tumors that invade celiac or hepatic artery ○ Central pancreatectomy performed for low-risk lesions (low malignant potential) in pancreatic neck/body – Not used for higher risk lesions due to inadequate lymphadenectomy and risk of pancreatic fistula ○ Enucleation performed for lesions with low malignant potential that are small and exophytic (often utilized for insulinomas) ○ Frey procedure and Puestow procedure are both utilized for treatment of chronic pancreatitis – Both result in lateral side-to-side pancreaticojejunostomy, with additional resection of portions of pancreatic head in Frey procedure ○ Laparoscopic technique is increasingly utilized at highvolume surgical centers (distal pancreatectomy > Whipple procedure)

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CT Findings • Normal findings immediately after Whipple procedure ○ Small free fluid, edema, and fat stranding in surgical bed with reactive subcentimeter lymph nodes in mesentery ○ Pneumobilia is an expected finding after Whipple procedure due to hepaticojejunostomy ○ Mild biliary dilatation frequently present due to anastomotic edema at hepaticojejunostomy ○ Thickening at gastrojejunostomy due to edema ○ Mild pancreatic duct dilatation due to anastomotic edema at pancreaticojejunostomy ○ Pancreatic duct stent (thin linear radiodensity) often placed during surgery (traversing pancreaticojejunostomy) to risk of pancreatic fistula – Will eventually pass into bowel over time on its own ○ Small free air expected for 14 days after surgery • Complications ○ Pancreatic fistula – Leakage of amylase-rich fluid from pancreatic duct (either at pancreaticojejunal anastomosis or at site of parenchymal injury)

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– Should be suspected when focal fluid collection, greater than expected ectopic gas, or hematoma identified directly adjacent to pancreaticojejunostomy □ Fluid and gas may be visualized in direct contiguity with suture line Abscess – Rim enhancing fluid collection ± internal ectopic gas – Abscesses following Whipple may be intrahepatic, in surgical bed, or in subphrenic, subhepatic, or retroperitoneal spaces – Abscesses following distal pancreatectomy are typically in left subphrenic or left subhepatic spaces Gastrojejunostomy and hepaticojejunostomy leaks – Both are uncommon complications, but hepaticojejunostomy leaks are more common – Should be suspected in acute setting when focal fluid collection visualized in close contiguity to anastomosis (usually with greater than expected ectopic gas) Postoperative pancreatitis – May be difficult to distinguish from normal postoperative inflammation in surgical bed – Suspect pancreatitis when fluid, edema, and fat stranding are disproportionately centered in pancreatic remnant (rather than surgical bed as a whole) Liver infarct – Uncommon due to dual blood supply of liver – Patients often have underlying vascular compromise (atherosclerosis, median arcuate ligament syndrome, etc.) that may be exacerbated by surgical complications, hypotension, etc. – Infarcts appear as wedge-shaped areas of hypodensity at periphery of liver Postoperative hemorrhage – May be due to bleeding from gastroduodenal artery stump (first 24 hours after surgery) or due to structural abnormality (pseudoaneurysm, vascular erosion) usually after 5th postoperative day – Hemorrhage usually in surgical bed, but can be intraluminal (usually within stomach or right upper quadrant jejunal loops near anastomosis) – Look for evidence of active extravasation or pseudoaneurysm: Acquisition of arterial phase CECT images critical if bleed is suspected Portomesenteric venous thrombosis – Increasingly common due to complex vascular reconstructions and use of venous interposition grafts – Superior mesenteric vein (SMV) thrombosis easier to overlook on axial images compared to coronal reconstructions Postoperative pseudocyst – Commonly seen after distal pancreatectomy, with loculated fluid collection immediately abutting suture line along distal aspect of pancreatic remnant Anastomotic strictures – Can occur at either pancreaticojejunostomy or hepaticojejunostomy – Suspect stricture in setting of progressive biliary or pancreatic ductal dilatation without evidence of obstructing recurrent tumor at anastomotic site

Pancreas

IMAGING

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Pancreas

Postoperative Pancreas

– Biliary anastomotic stricture may be associated with imaging signs of cholangitis (hyperenhancement and thickening of bile duct remnant, heterogeneous perfusion of liver parenchyma) ○ Delayed gastric emptying – Very common complication of unknown etiology that can be suggested when gastric remnant appears markedly dilated with large amount of retained ingested material and fluid ○ Tumor recurrence – Normal postoperative fibrosis and scarring typically appears linear (not mass-like), and is often located posterior to SMA/SMV (in Whipple procedure) – Tumor recurrence usually appears nodular and masslike and may narrow or occlude adjacent vessels

Imaging Recommendations • Best imaging tool ○ CECT is best for suspected postoperative complications ○ Biliary scintigraphy or MR with hepatobiliary agents (i.e., Eovist) may be helpful if biliary leak is suspected

DIFFERENTIAL DIAGNOSIS Normal Jejunal Loop • Jejunum in right upper quadrant may be collapsed and confused for postoperative abscess or hematoma

Rim-Enhancing Hepatic Metastases • May appear similar to rim-enhancing hepatic abscesses • Biopsy may be required if distinction between infection and metastases is not clinically or radiographically apparent

Postoperative Fat Necrosis in Mesentery or Greater Omentum • Mass with internal mixed attenuation and fat density, which may be mistaken for tumor recurrence or abscess • Fat density within mass is key to diagnosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most common immediate complications include – Intraabdominal abscess (6%), postoperative hemorrhage (4%), pancreatic fistula (6-14%), biliary leak (3.7%), pancreatitis (27%), portomesenteric venous thrombosis (17%), and pulmonary embolus ○ Pancreatic fistula defined as drain fluid amylase level 3x > serum amylase level on 3rd postoperative day (or > 50 cc amylase-rich fluid from drains per day) – Single most common cause of poor outcomes after Whipple procedure and strongly associated with multiple other complications, including abscess, hemorrhage, sepsis, and delayed gastric emptying – Mortality rates after fistula were once ~ 40%, but have now fallen to < 5% ○ Most common delayed complications following Whipple procedure include: Anastomotic stricture at biliary (8.2% at 5 years) or pancreatic (4.6% at 5 years) anastomosis, pseudocyst formation from pancreatic leak, and delayed gastric emptying (~ 50%) 1020

– Pancreatic duct strictures can result in pancreatic exocrine or endocrine insufficiency due to parenchymal atrophy – Delayed gastric emptying is clinically defined as persistent need for nasogastric tube after surgery □ Now most common postoperative complication, but usually resolves spontaneously

Natural History & Prognosis • Whipple procedure morbidity and mortality have dramatically fallen ○ Mortality rate was once ~ 25%, and is now 1-3%, despite pancreatic surgeries increasingly being performed for tumors previously considered unresectable ○ Decline in mortality mostly attributable to tertiary centers performing high volumes of pancreatic surgery, refinements of surgical technique, and increasing use of imaging to identify complications and guide percutaneous treatment ○ Patients at high-volume centers have morbidity and mortality compared to low-volume centers ○ Morbidity for Whipple procedure remains considerable, with complications in ~ 20% of patients • Distal pancreatectomy widely thought to be safer than Whipple procedure, but complication rate as high as 37%

Treatment • Pancreatic fistulas usually treated conservatively with drainage of fluid collections, antibiotics, and parenteral nutrition (surgery only considered for large pancreaticojejunal anastomotic dehiscence) ○ Octreotide may be helpful by pancreatic secretions ○ 80% of pancreatic fistulas heal with conservative management ○ Repeat surgery only necessary in a small % of patients • Postoperative fluid collections (abscess or biloma), particularly when sizeable (> 3 cm), are usually treated with percutaneous drainage • Postoperative hemorrhage is usually treated with emergent angiographic embolization (or rarely surgery) • Postoperative portomesenteric venous thrombosis is treated with systemic anticoagulation • Hepaticojejunostomy bile leaks are usually treated conservatively with percutaneous drainage • Anastomotic strictures are initially treated nonoperatively with balloon dilatation

DIAGNOSTIC CHECKLIST Consider • Differentiate normal postoperative findings (ectopic gas, fluid/edema in surgical bed, collapsed loops of jejunum in right upper quadrant) from true complications • Differentiate normal postoperative fibrosis (linear induration posterior to SMA and SMV with no mass effect) from true tumor recurrence, which is nodular and mass-like

SELECTED REFERENCES 1.

Raman SP et al: CT after pancreaticoduodenectomy: spectrum of normal findings and complications. AJR Am J Roentgenol. 201(1):2-13, 2013

Postoperative Pancreas Pancreas

(Left) Axial CECT in a patient recently status post Whipple procedure demonstrates a collection of fluid and gas in the porta hepatis adjacent to the hepaticojejunostomy. This was found to be the result of a hepaticojejunostomy leak, but was treated conservatively with a drain. (Right) Axial CECT after Whipple procedure demonstrates an enlarged, edematous, inflamed pancreas, compatible with post-Whipple pancreatitis.

(Left) Axial CECT after Whipple procedure demonstrates a large area of geographic hypodensity encompassing the entire left hepatic lobe, in keeping with a post-Whipple liver infarct. (Right) Coronal CECT in the 1st postoperative day after Whipple procedure demonstrates a large acute hematoma extending from the pancreaticojejunostomy downwards into the pelvis. The patient was taken to angiography where a gastroduodenal artery (GDA) stump bleed was identified and treated.

(Left) Coronal CECT a few days after Whipple procedure demonstrates a large intragastric hematoma with active extravasation . The patient was taken to angiography where a vascular erosion was found to be the cause of the bleed. PostWhipple bleeds can be either intraluminal or in the surgical bed. (Right) Coronal CECT after Whipple procedure demonstrates acute portal vein thrombus . The patient was treated with systemic anticoagulation.

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Pancreas

Pancreatic Transplantation KEY FACTS

IMAGING • Normal imaging appearance ○ CT: Homogeneous soft tissue mass in right abdomen with adjacent suture line at duodenal stump ○ MR: Normal pancreatic parenchyma is isointense to renal cortex on T1WI and isointense to muscle on T2WI ○ US: Normal pancreas transplant homogeneous and hypoechoic to adjacent mesenteric fat • Imaging of major complications ○ Allograft pancreatitis: Edema, enlargement and heterogeneous pancreas with peripancreatic fluid ○ Acute rejection: Enlargement and edema of graft with increased T2WI signal on MR ○ Chronic rejection: Small and atrophic graft with decreased T1 and T2WI signal on MR ○ Vascular complications: Venous thrombosis is more common than arterial – Arterial thrombosis on US: No Doppler flow within artery or graft parenchyma

(Left) Graphic shows the usual surgical anatomy of a combined pancreas-kidney transplant with pancreaticenteric drainage. The donor iliac artery is anastomosed to the donor superior mesenteric and splenic arteries to perfuse the pancreatic allograft (inset). The venous drainage can be to the iliac vein (as drawn) or the superior mesenteric vein. (Right) Coronal MRA of a kidneypancreas transplant reveals that the renal and the pancreatic allografts show normal perfusion and parenchymal enhancement.

(Left) Coronal NECT demonstrates the right lower quadrant transplant pancreas to be enlarged and hypodense with adjacent fat stranding and induration. Based on the CT findings, this could represent either graft ischemia or pancreatitis. (Right) Sagittal power Doppler ultrasound in the same patient demonstrates the pancreatic transplant to be enlarged and diffusely hypoechoic, without appreciable internal vascularity, compatible with infarction.

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– Venous thrombosis on US: Echogenic intraluminal thrombus, absent vascular flow, and high-resistance arterial waveforms with reversed diastolic flow – Graft infarction on US: Enlarged avascular transplant ○ Intraabdominal fluid collections: May represent abscess, seroma, lymphocele, urinoma, or pseudocyst

PATHOLOGY • Goal of pancreas transplantation is treatment of diabetes by restoring endogenous insulin secretion

CLINICAL ISSUES • Graft survival is better with combined pancreas-kidney transplant than with pancreas alone • Graft pancreatitis is common after transplantation ○ 35% experience mild, self-limited pancreatitis; usually related to reperfusion injury after surgery • Chronic rejection is leading cause of late allograft loss • Vascular thrombosis is 2nd leading cause of graft dysfunction (usually in acute postoperative setting)

Pancreatic Transplantation

General Features • Location ○ Pancreatic allograft usually placed on right side (renal allograft on left) – Graft in bladder drainage transplants is usually in right iliac fossa, parallel to ascending colon – Graft position in enteric drainage transplants is more variable, but usually vertical on right side • Surgical technique ○ Bladder drainage – Older technique that drains pancreatic secretions into bladder via duodenal interposition segment – Associated with many complications, including accelerated insulin resistance, atherosclerosis, urinary tract infections, and graft pancreatitis ○ Enteric drainage – Now considered preferred technique, with allograft head (which is obtained with segment of duodenum) placed in cephalic location with side-to-side pancreatic-duodenal to jejunal anastomosis ○ Venous drainage – Donor portal vein anastomosed to systemic vein (common/external iliac or IVC) or mesenteric vein (more physiologic, but technically more difficult) ○ Arterial supply – Donor iliac artery "Y" graft with one end anastomosed to recipient's common, external, or internal iliac artery and "Y" limbs anastomosed to donor splenic and superior mesenteric arteries (end blindly after supplying allograft) • Normal imaging appearance ○ CT: IV contrast often not used due to renal toxicity and concurrent chronic renal failure – Oral contrast very useful (and usually necessary) to distinguish graft from adjacent bowel – Homogeneous soft tissue mass closely associated with adjacent bowel (typically with adjacent suture line at duodenal stump) – Graft may be normally enlarged and heterogeneous in early post-transplant period (< 4 weeks) with surrounding fluid and hematoma, and should not be confused with pancreatitis □ Pancreas graft gradually becomes well defined and similar in density (on both NECT and CECT) to normal pancreas, with no surrounding fluid ○ MR:Normal pancreas parenchyma is isointense to renal cortex on T1WI and isointense to muscle on T2WI • Imaging of major complications ○ Allograft pancreatitis: Edema, enlargement, and heterogeneous enhancement of pancreas on CT and MR, typically with peripancreatic fluid – Peripancreatic fluid can evolve into loculated collections or pseudocysts ○ Acute rejection: Nonspecific CT findings, with enlargement and edema of graft – MR: Increased parenchymal T2WI signal and heterogeneous enhancement due to edema ○ Chronic rejection: Nonspecific CT findings, with small and atrophic graft

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– MR: Decreased signal intensity on T1 and T2 due to parenchymal fibrosis and reduced extracellular fluid □ Secretin-augmented MR may demonstrate diminished exocrine function with secretion of pancreatic juice from dysfunctional allograft Vascular complications: Venous thrombosis is more common than arterial – MRA and CTA can map arterial and venous anatomy to identify sites of stenosis or thrombosis □ More typically a troubleshooting tool when ultrasound findings are equivocal – Pseudoaneurysms and arteriovenous fistulae may be due to prior biopsy, pancreatitis, or surgical technique – Graft infarction: Heterogeneous enhancement of pancreas on MR or CT ± liquefied/necrotic parenchyma ± gas bubbles □ Impossible to distinguish infarction from infected pancreatic necrosis after pancreatitis, although treatment is same (surgical resection) □ Ischemia or necrosis can affect graft focally or diffusely Postoperative hemorrhage: May be visualized on routine postoperative US, but full extent (and presence of active extravasation) best seen with CECT Intraabdominal fluid collections: May represent abscess, seroma, lymphocele, urinoma, or pseudocyst – Presence of excessive extraluminal gas, fluid, or oral contrast should raise concern for leakage at enteric anastomosis Post-transplant lymphoproliferative disorder (PTLD): New lymphadenopathy or solid masses in abdomen after transplant should raise suspicion

Pancreas

IMAGING

Ultrasonographic Findings • May not adequately visualize pancreas in ~ 20% of cases ○ Normal pancreas transplant should be homogeneous and hypoechoic to adjacent mesenteric fat ○ "Y" arterial graft and graft vein should be visualized using color or power Doppler • Unable to distinguish among different causes of parenchymal abnormalities ○ Acute processes (rejection vs. pancreatitis) result in enlarged, hypoechoic, or heterogeneous gland – Pancreatitis more likely to result in perigraft free fluid ○ Chronic rejection results in shrunken, atrophic gland with increased echogenicity ○ Elevated resistive indices nonspecific and may be seen with rejection, ischemia, or pancreatitis • Color Doppler, power Doppler and spectral Doppler ○ Arterial thrombosis: No color or power Doppler flow within artery and graft parenchyma ○ Venous thrombosis: Echogenic intraluminal thrombus, absent flow in vessel and possibly in graft parenchyma, and high-resistance arterial waveforms with possible reversed diastolic flow ○ Infarction: Little or no flow within enlarged, heterogeneous allograft on color or power Doppler

Imaging Recommendations • Best imaging tool ○ Ultrasound is best initial screening tool, with Doppler allowing evaluation of vasculature and perfusion of graft 1023

Pancreas

Pancreatic Transplantation ○ CECT and MR are useful troubleshooting tools for evaluation of vasculature and complications

Nonvascular Interventions • US-guided biopsy of allograft is safe and effective means to distinguish rejection from other causes of graft dysfunction ○ Technical success rate > 95%; complication rate < 3%

PATHOLOGY General Features • Primary goal for pancreas transplantation is treatment of diabetes by restoring endogenous insulin secretion and preventing progression of diabetes complications • Transplants typically performed in 2 groups ○ Patients with end-stage renal disease who have or will have kidney transplant: Pancreas transplant improves odds of kidney survival by preventing hyperglycemia – Most often combined kidney-pancreas transplant ○ Patients with severe metabolic complications from diabetes who have failed exogenous insulin therapy may undergo pancreas transplant even in absence of chronic kidney disease – Usually only pancreas transplant without kidney

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Pancreatitis – Right lower quadrant pain; amylase, lipase – Can result in pseudocyst formation (usually weeks after bout of pancreatitis) ○ Vascular thrombosis – Sudden loss of graft function (e.g., hyperglycemia, increased insulin dependence) and focal tenderness over swollen graft – Venous thrombosis is more common than arterial – More likely in acute postoperative setting (< 30 days) than in chronic setting – May be more likely in setting of pancreatitis or underlying pseudoaneurysm ○ Postoperative hemorrhage – Complicates 1% of pancreatic transplantations – Patients present with pain and falling hematocrit – Hemorrhage in immediate postoperative period usually due to leak from vascular anastomosis, while later hemorrhage often due to anticoagulation ○ Rejection – Affects up to 40% of pancreatic grafts – May be hyperacute, acute, or chronic, and typically presents with diminished graft function ○ Anastomotic leak – Occurs in 14% of cases in bladder-drained grafts and 2-10% of enteric-drainage cases – Severe local pain but usually preserved graft function – Presence of ectopic gas, fluid, or enteric contrast should raise suspicion for this diagnosis – Early leaks due to surgical technique, while later leaks due to pancreatitis, rejection, or infection ○ Urologic complications (with bladder drainage) – Transient hematuria in almost all patients 1024

– Cystitis, urethritis, and stricture are common

Demographics • Epidemiology ○ > 37,000 transplants since 1st transplant in 1966 ○ > 1,300 pancreas transplantations in USA in 2008 ○ 75% are combined kidney-pancreas transplants

Natural History & Prognosis • Graft survival is better with combined pancreas-kidney transplant than with pancreas alone ○ With simultaneous pancreas-kidney transplantation, 1year graft survival is 80-85% and 5-year graft survival is 65% ○ With pancreas transplant alone, 1-year and 10-year graft survival is only 78% and 27%, respectively ○ May be related to relative ease of identifying rejection in patients with kidney transplant (as creatinine serves as marker for graft function) • 1-year patient survival after transplant is 92-98% • Graft pancreatitis is relatively common immediately after transplantation ○ 35% of patients experience mild, self-limited pancreatitis; usually related to reperfusion injury after surgery – Hyperamylasemia is common in 1st week post transplantation ○ More common with bladder drainage transplant technique • Chronic rejection is leading cause of late allograft loss ○ Allograft rejection is usually confirmed by biopsy • Vascular thrombosis is 2nd leading cause of graft dysfunction ○ Accounts for > 50% of early graft failures (< 30 days) and < 10% of late graft failures (> 30 days) ○ Incidence of thrombosis is 2-19% of all transplants ○ Can result in parenchymal infarction or necrosis and may require pancreatectomy

DIAGNOSTIC CHECKLIST Consider • Imaging of pancreas transplant should begin with US, with MR or CT used as troubleshooting tools in cases of suspected complications

Image Interpretation Pearls • Imaging lacks specificity in differentiating nonvascular etiologies of graft dysfunction, and biopsy may be required

SELECTED REFERENCES 1. 2.

Khaja MS et al: Vascular Complications of Transplantation: Part 2: Pancreatic Transplants. Cardiovasc Intervent Radiol. ePub, 2014 Vincent M et al: Multi detector computed tomography (MDCT) for the diagnosis of early complications after pancreas transplantation. Abdom Imaging. ePub, 2014

Pancreatic Transplantation Pancreas

(Left) Axial CECT shows the pancreatic allograft with mild swelling of the gland and peripancreatic stranding, indicating mild pancreatitis, a finding seen frequently in the immediate post-transplant period. (Right) Axial CECT shows diffuse parenchymal enlargement and heterogeneity with scattered areas of decreased enhancement in the transplant pancreas , consistent with post-transplant pancreatitis. Note the normally enhancing transplanted kidney in the left lower quadrant .

(Left) Coronal CECT shows a rim-enhancing fluid collection surrounding the pancreas transplant . Note the communication between the fluid collection and the duodenum consistent with suture line dehiscence . Emergent surgical drainage and repair was performed. (Right) Axial CECT demonstrates a fluid collection adjacent to the transplant pancreas in a patient with a history of pancreatitis, compatible with a pseudocyst. A transplant kidney is noted in the left lower quadrant .

(Left) Coronal MRA shows normal appearance and enhancement of the right lower quadrant renal allograft , while the branching arterial supply to the pancreatic allograft is totally occluded. The infarcted pancreatic allograft was then resected. (Right) Axial CECT shows gas and fluid replacing the pancreatic allograft in the right iliac fossa, with a fistulous tract to the skin. At resection, infected necrosis of the pancreatic allograft related to pancreatitis was noted.

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Pancreas

Pancreatic Serous Cystadenoma KEY FACTS

TERMINOLOGY • Benign pancreatic tumor lined by glycogen-rich cells that arise from acinar cells

IMAGING • Well-circumscribed mass with a lobulated contour and three primary morphologies ○ Microcystic adenoma (i.e., classic serous cystadenoma) – Honeycomb or sponge pattern with innumerable internal tiny cysts, enhancing septations, and central scar with calcification ○ Macrocystic serous cystadenoma (usually unilocular) – Single or few cystic components or locules ○ "Solid" serous adenoma – Enhancing septa predominate over cystic spaces, producing solid hyperenhancing lesion on imaging • Peripheral rim enhancement on arterial or venous phase • Calcifications common, and can be peripheral (most common), central, or along septations

(Left) Graphic shows a mass in the pancreatic head. The mass has a sponge or "honeycomb" appearance and is characterized by innumerable small cysts, a central scar, and no obstruction of the pancreatic or bile duct. (Right) Axial CECT in an elderly woman with vague abdominal pain shows a large lobulated mass in the pancreatic head. Note the sponge-like appearance with multiple cystic spaces surrounding an enhancing fibrous scar , typical of a serous cystadenoma.

(Left) Axial T2 FS MR of a pancreatic lesion thought to be indeterminate on CT (not shown) demonstrates a cystic mass composed of many tiny internal cysts, classic for a "microcystic" serous cystadenoma. (Right) Endoscopic ultrasound of a serous cystadenoma demonstrates the characteristic multiple tiny cysts . Aspiration of the cyst contents revealed thin fluid with no cellular atypia or elevated tumor markers.

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• Does not typically result in biliary or pancreatic ductal obstruction or pancreatic atrophy • MR able to better characterize internal morphology than CT, with sensitivity for microcysts

CLINICAL ISSUES • Many lesions (~ 40%) are discovered incidentally in asymptomatic patients • Often described as "grandmother tumor" due to preponderance in older women • Lesions measuring > 4 cm have been shown to grow more quickly and cause more symptoms • Treatment ○ Asymptomatic small tumors with classic imaging features: Serial imaging follow-up ○ Indeterminate lesions without classic imaging appearance: MR or endoscopic ultrasound ○ Complete surgical excision for large tumors (especially > 4 cm) with mass effect or patient symptomatology

Pancreatic Serous Cystadenoma

Intraductal Papillary Mucinous Neoplasm (IPMN)

Definitions

• Communication with main pancreatic duct may be visible • Cluster of dilated ducts may mimic serous cystadenoma

• Benign pancreatic tumors lined by glycogen-rich cells that arise from acinar cells

Pancreatic Islet Cell Tumors

IMAGING General Features • Location ○ Classically thought to be more common in pancreatic head • Size ○ Indolent lesions that can rarely become large masses

CT Findings • Well-circumscribed mass with lobulated contour and 3 primary morphologies ○ Microcystic adenoma (i.e., classic serous cystadenoma) – Accounts for only 20% of all serous cystadenomas – Honeycomb or sponge pattern with innumerable internal tiny cysts and enhancing septations (> 6 cysts measuring < 2 cm in size) – Central scar with calcification ○ Macrocystic serous cystadenoma (usually unilocular) – 10-25% of all serous cystadenomas – Single or few cystic components or locules – Thin, nonenhancing, imperceptible wall ○ "Solid" serous adenoma – Enhancing septa predominate over cystic spaces, producing solid lesion on imaging – Markedly hypervascular with peripheral enhancement • Rim enhancement with hypertrophied feeding arteries often appearing draped around margins of mass • Usually no biliary/pancreatic ductal obstruction or pancreatic atrophy • Calcifications common (36%) either peripherally (most often), centrally, or along septations • No vascular encasement, narrowing, or occlusion

MR Findings • MR may better characterize internal morphology than CT, with sensitivity for microcysts • T1WI: Cystic components hypointense • T2WI: Cystic components hyperintense and fibrous components/central scar hypointense • T1WI C+: Enhancement of septations/lesion periphery with delayed enhancement of central scar • DWI: Variable; cannot differentiate mucinous vs. serous

Ultrasonographic Findings • Individual cysts may not be visible if innumerable small cysts, and lesion may appear solid and hyperechoic with acoustic through transmission • Endoscopic US: High-resolution imaging of mass may better delineate internal cysts, "sponge" morphology, central scar, and internal calcification

DIFFERENTIAL DIAGNOSIS Mucinous Cystic Pancreatic Tumor

Pancreas

TERMINOLOGY

• Solid serous adenomas appear solid/hypervascular and indistinguishable from neuroendocrine tumors

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Often (~ 40%) incidentally discovered without symptoms ○ Larger lesions may cause symptoms due to mass effect • Laboratory data ○ Serum carcinoembryonic antigen (CEA): Negative ○ Endoscopic US with cyst aspiration: Low CEA, CA 19-9, mucin, amylase; no evidence of atypia on cytology

Demographics • Age ○ Middle and elderly age group (mean 68 years old) • Gender ○ More common in women (M:F = 1:4) ○ "Grandmother tumor"; preponderance in older women • Epidemiology ○ Accounts for 10-15% of all pancreatic cysts ○ May be multiple with Von Hippel-Lindau syndrome

Natural History & Prognosis • Vast majority of lesions benign with no malignant potential ○ Even if benign, lesions can grow and cause symptoms (pain, obstruction) as a result of mass effect ○ Lesions measuring > 4 cm have been shown to grow more quickly (1.6 cm/year) and 3x more likely to cause symptoms compared to lesions < 4 cm (0.12 cm/year) • Small percentage (< 5%) are locally invasive/aggressive • Rarely (< 1%) malignant with metastasis (usually liver)

Treatment • Asymptomatic small tumors with classic imaging features: Serial imaging follow-up without surgical excision • Indeterminate lesions without classic imaging appearance: MR or endoscopic ultrasound • Complete surgical excision for large tumors (especially > 4 cm) with mass effect or patient symptomatology

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Well-demarcated, lobulated cystic mass composed of innumerable small cysts (1-20 mm) separated by thin septa

SELECTED REFERENCES 1.

2. 3.

Chu LC et al: Characterization of pancreatic serous cystadenoma on dualphase multidetector computed tomography. J Comput Assist Tomogr. 38(2):258-63, 2014 Raman SP et al: Endoscopic ultrasound and pancreatic applications: what the radiologist needs to know. Abdom Imaging. 38(6):1360-72, 2013 Zaheer A et al: Incidentally detected cystic lesions of the pancreas on CT: review of literature and management suggestions. Abdom Imaging. 38(2):331-41, 2013

• Few (< 6) large (> 2 cm) cystic components ± mural nodularity ± calcification (in peripheral wall or septa) 1027

Pancreas

Pancreatic Serous Cystadenoma

(Left) Coronal minimum intensity projection image from a CECT in an elderly woman shows a large mass originating from the tail of the pancreas. Note the distinctive "honeycomb" morphology of this serous cystadenoma. (Right) Axial CECT image demonstrates a hypervascular solid mass that has a welldefined scar with central calcification . This was found at surgery to be a "solid" serous cystadenoma. Serous tumors can rarely be indistinguishable from a neuroendocrine tumor.

(Left) Axial CECT demonstrates a mixed cystic and solid mass arising from the pancreatic head. Note that there are areas of more solid hyperenhancement , reflecting many enhancing septations predominating over cystic spaces. (Right) Axial T2 MR in the same patient better demonstrates the microcystic morphology of the lesion, characteristic of a serous cystadenoma. MR can be very helpful for better delineating the internal morphology of these lesions when indeterminate on CT.

(Left) Coronal CECT demonstrates a simpleappearing cystic lesion arising from the pancreatic tail. While the differential diagnosis includes a mucinous cystic neoplasm and IPMN, this was found to be a unilocular serous cystadenoma at surgery. (Right) Axial CECT demonstrates multiple internal septations within a large cystic pancreatic mass . While a large mucinous cystic neoplasm could be considered, this represents an oligocystic variant of a serous cystadenoma with large macrocysts.

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Pancreatic Serous Cystadenoma Pancreas

(Left) Axial CECT demonstrates a large "sponge" lesion in the pancreatic tail with innumerable tiny cysts, a lobulated contour, and peripheral enhancement, characteristic of a serous cystadenoma. (Right) Axial CECT in a delayed phase for the same patient nicely demonstrates delayed enhancement of the central scar within the center of the mass , a common feature of serous cystadenomas.

(Left) Coronal MRCP demonstrates the classic microcystic architecture of a serous cystadenoma , with innumerable tiny T2 bright cysts, intervening septations, and a central T2 hypointense scar . (Right) Axial T2WI MR demonstrates the internal microcystic structure of a pancreatic mass , which also demonstrates a lobulated contour, characteristic of a serous cystadenoma. In some cases, MR can better delineate the internal morphology of these lesions compared to CT.

(Left) Axial CECT shows a predominantly cystic mass in the body of the pancreas. Note the calcifications within its central fibrous scar, a characteristic appearance for a microcystic serous cystadenoma. (Right) Coronal CECT MIP reconstruction illustrates a markedly hypervascular solid pancreatic mass , as well as feeding hypertrophied vessels arising from the gastroduodenal artery . This was found to be a "solid" serous cystadenoma at resection, an entity that can look identical to neuroendocrine tumors.

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Pancreas

Nonneoplastic Pancreatic Cysts KEY FACTS

TERMINOLOGY • Group of nonneoplastic, noninflammatory, benign pancreatic cysts comprising several different histopathologic entities

IMAGING • Imaging features can show some variability, since this category encompasses several histopathologically distinct types of nonneoplastic cysts ○ Usually unilocular, well-defined cyst with sharp margin and thin imperceptible wall – Typically no internal complexity, septations, nodularity, or calcifications – Usually no communication with pancreatic duct – Usually single cyst but frequently multiple in patients with underlying syndrome ○ Less commonly, imaging features can overlap with neoplastic pancreatic cysts, and lesions can demonstrate more complexity (multiloculation, calcifications, etc.)

(Left) Axial CECT in an asymptomatic patient demonstrates a simpleappearing, thin-walled cyst in the pancreatic neck. (Right) Endoscopic ultrasound in the same patient shows a simple cyst in the neck of the pancreas. There is no mural nodularity or other sign of complexity. Aspiration demonstrated clear serous fluid with no elevated tumor markers. It was elected to follow this cyst with sonography. It has remained stable for several years and is presumably a nonneoplastic simple cyst.

(Left) Axial CECT shows a small, simple-appearing cyst in the pancreatic head/neck. The wall of the cyst is imperceptible and there are no internal septations or other signs of complexity. (Right) Endoscopic ultrasound in the same patient confirms the simple appearance of the cyst . Needle aspiration of the cyst demonstrated clear serous fluid with no malignant cells or elevated tumor markers, consistent with a nonneoplastic, simple cyst.

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– Lymphoepithelial cysts are more commonly complex (may have macroscopic fat) and can be intrapancreatic, abut pancreas, or appear exophytic □ May demonstrate signal loss on out-of-phase gradient-echo MR images (due to intracellular lipid)

PATHOLOGY • Syndromes account for most nonneoplastic cysts diagnosed prospectively in clinical practice ○ von Hippel-Lindau (VHL) disease, autosomal dominant polycystic kidney (ADPKD), and cystic fibrosis (CF)

CLINICAL ISSUES • ACR incidental findings committee suggests simple pancreatic cysts measuring 2 cm can be safely followed • Simple pancreatic cysts in setting of a known syndrome (VHL, ADPKD, CF) are almost certainly benign • Larger lesions or lesions with suspicious morphologic features often require EUS or cyst aspiration and consideration for surgical resection

Nonneoplastic Pancreatic Cysts

Synonyms

○ Rarely, some histopathologic subtypes of nonneoplastic cysts (i.e., retention cysts) may communicate with pancreatic duct

• Congenital, true, or epithelial pancreatic cyst

Ultrasonographic Findings

Definitions

• Most often anechoic with no internal complexity or echoes

• Group of nonneoplastic, noninflammatory, benign pancreatic cysts comprising several different histopathologic entities

Radiographic Findings

IMAGING General Features • Best diagnostic clue ○ Simple-appearing cyst with no septations or mural nodularity in a patient with no history of pancreatitis – Consider strongly in patients with history of cystic fibrosis, autosomal dominant polycystic kidney disease (ADPKD), or von Hippel-Lindau (VHL) • Size ○ Usually quite small, although rarely can be much larger: Giant cysts as large as 15 cm in diameter reported • Morphology ○ Usually unilocular with round or oval shape, smooth thin wall, and absence of internal complexity ○ Solitary or multiple (when associated with cystic syndromes)

CT Findings • Imaging features can show some variability, since this category encompasses several histopathologically distinct types of nonneoplastic cysts ○ Most nonneoplastic cysts are unilocular and well defined with a sharp margin and thin imperceptible wall ○ Typically no internal complexity, septations, nodularity, or calcifications ○ Usually no discernible communication with pancreatic duct ○ Usually single isolated cyst, but often multiple in patients with underlying syndrome • Less commonly, imaging features can overlap with neoplastic pancreatic cysts, and lesions can demonstrate more complexity (multiloculation, calcifications, etc.) ○ Lymphoepithelial cysts have been described as more commonly demonstrating complexity (and even macroscopic fat) and may be either intrapancreatic, abut pancreas, or appear exophytic – May be connected with pancreas by tiny, imperceptible stalk and appear exophytic or extrapancreatic – Appear multilocular in 60% of cases

MR Findings • Most nonneoplastic cysts are simple in appearance (hypointense on T1WI, hyperintense on T2WI, no enhancement or complexity) ○ Lesions may demonstrate more complexity and be indistinguishable from a cystic neoplasm ○ Lymphoepithelial cysts may demonstrate complexity and signal loss on out-of-phase gradient-echo images due to intracellular lipid • Usually no communication with pancreatic duct on MRCP

Pancreas

TERMINOLOGY

• ERCP: Usually no communication between cyst and duct

Imaging Recommendations • Best imaging tool ○ CECT or MR followed by endoscopic US (EUS)

DIFFERENTIAL DIAGNOSIS Pancreatic Pseudocyst • More often complex in appearance with discrete wall • Usually history or imaging stigmata of prior pancreatitis • Much more common than nonneoplastic cysts, even in pediatric age group

Pancreatic Intraductal Papillary Mucinous Neoplasm (IPMN) • Much more common than nonneoplastic cysts • Side-branch IPMNs usually demonstrate communication with adjacent pancreatic duct • If simple in appearance with no discernible communication to pancreatic duct, side-branch IPMN may not be distinguishable from nonneoplastic cyst

Pancreatic Serous Cystadenoma • Classic appearance is honeycomb morphology with multiple (> 6) microcysts and central scar with calcification • Unilocular or macrocystic variants of serous cystadenoma may be indistinguishable from true cysts except by histology • Patients with VHL also have increased incidence of serous cystadenoma: Nonneoplastic cysts and serous cystadenoma may coexist

Mucinous Cystic Neoplasm (MCN) • Complex multilocular cystic mass with a few macrocysts, usually in tail of pancreas ○ Often will demonstrate thick wall, mural nodularity, or thick septations, particularly when malignant • Unilocular, simple MCN may be indistinguishable from true cyst except by histology

Lymphangioma (Mesenteric Cyst) • Multiseptated mesenteric or peripancreatic cystic mass abutting pancreas • Often will have a "feathery" morphology on imaging with multiple locules • Can be small and simple in appearance and might appear indistinguishable from primary nonneoplastic pancreatic cyst when located adjacent to pancreas

Cystic Neuroendocrine Tumor • Usually demonstrates a surrounding rim of avid enhancement or hypervascular mural nodularity (most evident on arterial phase imaging)

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Pancreas

Nonneoplastic Pancreatic Cysts

• Patients with VHL also have increased incidence of neuroendocrine tumors: Nonneoplastic cysts and cystic neuroendocrine tumors may coexist

PATHOLOGY General Features • Syndromes account for most nonneoplastic cysts diagnosed prospectively in clinical practice ○ VHL ○ ADPKD ○ Beckwith-Wiedemann syndrome ○ Cystic fibrosis • Isolated nonneoplastic cysts without a syndrome are far more rare in clinical practice

Staging, Grading, & Classification • While generally grouped together into a category of nonneoplastic pancreatic cysts, these cysts can be further subdivided into multiple distinct histopathologic subtypes ○ Retention cysts: Cystic dilatation of pancreatic duct side branch due to intraluminal obstruction – Can be congenital or due to obstruction of side branch by mucin, chronic pancreatitis, or calculi – Communicate with pancreatic duct making differentiation from IPMN difficult ○ "True" cysts: Lined by cuboidal epithelium and do not communicate with pancreatic duct – Rare entity in adults, with only a few reports in literature, and more common in children ○ Squamoid cysts: Lined by squamous epithelium ○ Mucinous nonneoplastic cysts: Mucinous epithelium, no cellular atypia, and no communication with pancreatic duct – Presence of mucin makes preoperative diagnosis with EUS cyst aspiration very difficult, and these lesions are almost always resected and diagnosed on postoperative histopathology ○ Enterogenous cysts: Congenital cysts derived from foregut filled with serous and mucoid fluid ○ Endometrial cysts: Extremely rare manifestation of endometriosis in pancreas ○ Lymphoepithelial cysts: Rare benign cysts that may be either intrapancreatic or extrapancreatic and are lined by squamous epithelium and layer of lymphoid tissue – Filled with squamous material, lymphocytes, and keratinaceous debris but no atypia or neoplastic cells – Usually occur in older males ○ Acinar cell cystadenomas: Lined by benign acinar cells ○ Pancreatic enteric duplication cysts: Rare and most common in children; can present with pancreatitis

Gross Pathologic & Surgical Features • True epithelial lining (absent in pseudocysts)

CLINICAL ISSUES

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• Other signs/symptoms ○ EUS-guided cyst aspiration yields fluid with low CEA, low amylase, and negative cytology

Demographics • Epidemiology ○ Nonneoplastic cysts are very rare, < 1% of all pancreatic cysts • Lymphoepithelial cysts are most common in men between 5th and 6th decades • Other types of nonneoplastic cysts vary in gender and age predispositions, but congenital nonneoplastic cysts can rarely be visualized in utero on prenatal US

Natural History & Prognosis • While management of incidental pancreatic cysts is controversial and varies depending on individual specialty society, simple-appearing pancreatic cysts 2 cm in asymptomatic adults are rarely of any clinical significance ○ ACR incidental findings committee in 2010 suggested simple pancreatic cysts measuring 2 cm could be safely followed • Simple pancreatic cysts in setting of a known syndrome (VHL, cystic fibrosis, ADPKD) are almost certainly benign ○ Careful attention must be paid in patients with VHL to differentiate nonneoplastic cysts from cystic neuroendocrine tumors

Treatment • Most lesions can be safely followed with imaging surveillance • Larger lesions or lesions with suspicious morphologic features often require EUS or cyst aspiration and consideration for surgical resection • Nonneoplastic cysts are not uncommonly resected due to difficulty in differentiating them from cystic pancreatic neoplasms

DIAGNOSTIC CHECKLIST Consider • Nonneoplastic pancreatic cysts are much less common than both pancreatic pseudocysts and cystic pancreatic neoplasms • Consider nonneoplastic cysts most strongly in patients with history of cystic fibrosis, ADPKD, Beckwith-Wiedemann, or VHL

Image Interpretation Pearls • Based on imaging alone, nonneoplastic cysts cannot be reliably distinguished from simple-appearing neoplastic cysts (such as IPMNs) • Endoscopic US with cyst aspiration can play a valuable role in risk stratifying pancreatic cysts with indeterminate imaging features

SELECTED REFERENCES

Presentation

1.

• Most common signs/symptoms ○ Almost always an incidental finding in patients being imaged for other reasons ○ Rarely symptomatic (pain, pancreatitis) due to size and mass effect

2.

Al-Salem AH et al: Congenital pancreatic cyst: diagnosis and management. J Pediatr Gastroenterol Nutr. 59(4):e38-40, 2014 Assifi MM et al: Non-neoplastic epithelial cysts of the pancreas: a rare, benign entity. J Gastrointest Surg. 18(3):523-31, 2014

Nonneoplastic Pancreatic Cysts Pancreas

(Left) Axial CECT demonstrates innumerable tiny nonneoplastic cysts in the pancreas, as well as multiple left-sided renal cysts, a common constellation of findings in von Hippel-Lindau (VHL). VHL patients can often demonstrate diffuse cystic replacement of the pancreas. (Right) Coronal MRCP with MIP reconstruction demonstrates extensive replacement of the entire pancreas with T2 bright cysts in a patient with VHL.

(Left) Axial CECT in a patient with VHL demonstrates an avidly enhancing left-sided renal cell carcinoma . The well-defined, simple-appearing cyst in the pancreas almost certainly represents a nonneoplastic pancreatic cyst, very common in VHL patients. (Right) Axial CECT in a patient with cystic fibrosis shows fatty replacement and pseudohypertrophy of the pancreas , characteristic of pancreatic involvement with this disease. Notice also the thin-walled retention cyst in the tail of the pancreas .

(Left) Axial CECT in a patient with cystic fibrosis demonstrates a well-defined simple-appearing cyst in the pancreatic head. Nonneoplastic cysts are a common finding in cystic fibrosis patients. (Right) Axial CECT demonstrates a cyst in the pancreatic tail. Notice the internal complexity within the cyst, including possible mural nodularity and a small focus of internal fat density . This was found to be a lymphoepithelial cyst at resection, as these lesions can sometimes demonstrate internal fat.

1033

Pancreas

Pancreatic Ductal Carcinoma KEY FACTS

TERMINOLOGY • Malignancy arising from ductal epithelium of exocrine pancreas

IMAGING • CT: Poorly marginated, hypodense mass with tendency to infiltrate posteriorly into retroperitoneum ○ Strong tendency to obstruct pancreatic and common bile ducts with abrupt ductal cutoff at site of obstruction ○ Pancreatic parenchymal atrophy upstream from mass ○ Soft tissue infiltration to involve adjacent vessels and organs (e.g., duodenum, bowel, stomach, and adrenals) ○ Most common sites of distant metastatic disease are liver, peritoneum, and lungs ○ Arterial involvement quantified as < 180° or 180° tumoral involvement of vessel circumference ○ Venous involvement may involve abutment, encasement, narrowing, or occlusion

(Left) Graphic shows pancreatic head carcinoma encasing and obstructing the pancreatic and distal bile ducts. There is encasement of the superior mesenteric vessels and spread to celiac nodes . Note the atrophy of the distal body-tail segments . (Right) Axial CECT in the venous phase demonstrates a poorly marginated hypodense mass in the pancreatic body, typical for pancreatic adenocarcinoma. The mass abuts the distal celiac trunk and the hepatic artery , with < 180° involvement of each.

(Left) Coronal CECT demonstrates a subtle hypodense mass in the pancreatic head resulting in obstruction and upstream dilatation of the pancreatic duct . The presence of pancreatic ductal dilatation and abrupt cut-off should always prompt careful search for a pancreatic mass. (Right) Sagittal CECT demonstrates a poorly marginated pancreatic cancer encasing the SMA, with 360° involvement. This degree of encasement almost certainly makes this tumor unresectable.

1034

• MR: Tumor conspicuous on T1WI, appearing low signal and juxtaposed against high signal pancreatic parenchyma ○ T2WI less useful, as tumors isointense to pancreas ○ Conspicuity on T1WI C+ similar to CT, with tumors demonstrating progressive delayed enhancement

CLINICAL ISSUES • Most common malignant tumor of exocrine pancreas and accounts for > 95% of pancreatic malignancies • Most common symptoms are jaundice, weight loss, abdominal pain, and back pain ○ Often asymptomatic until late in course, particularly body/tail tumors that do not cause jaundice • Only potentially curative treatment is complete surgical resection with negative surgical margins • Only 15-20% of patients candidates for surgery at presentation, with 5-year survival of ~ 20% after surgery • 5-year survival rate is < 5% without surgery with median survival of 3.5 months

Pancreatic Ductal Carcinoma

Synonyms • Pancreatic adenocarcinoma, pancreatic cancer

Definitions • Malignancy arising from ductal epithelium of exocrine pancreas

IMAGING General Features • Best diagnostic clue ○ Poorly marginated, hypoenhancing mass with abrupt obstruction of pancreatic duct ± common bile duct • Location ○ Head (60%), body (20%), diffuse (15%), tail (5%) • Size ○ Variable; average size 2-3 cm

CT Findings • CT sensitivity for pancreatic cancer is excellent (~ 97%) ○ Excellent modality for determining unresectability (positive predictive value for unresectability of 89-100%) ○ Less effective in determining resectability, as only 6091% of tumors found to be resectable on CT are actually resectable at surgery • Poorly marginated, hypodense mass with tendency to infiltrate posteriorly into retroperitoneum ○ Tumor most conspicuous in portal venous (~ 70 seconds) and pancreatic (~ 40 seconds) contrast phases ○ 5% of tumors isodense to pancreas on all phases, requiring attention to secondary signs of tumor ○ Tumor virtually never calcifies in absence of treatment • Secondary signs of tumor ○ Strong tendency to obstruct pancreatic and common bile ducts with abrupt ductal cutoff at site of obstruction ○ Pancreatic parenchymal atrophy upstream from mass ○ Abnormal contour of pancreas with loss of normal fatty lobulation and texture ○ Soft tissue infiltration to involve adjacent vessels and organs (e.g., duodenum, bowel, stomach, and adrenals) • Distant metastatic disease ○ Most common sites are liver, peritoneum, and lungs ○ Regional lymph nodes frequently involved, but CT inaccurate for involvement (sensitivity < 20%) • CT best modality for determining vascular invasion ○ Arterial involvement quantified as < 180° or 180° tumoral involvement of vessel circumference ○ Venous involvement determined based on degree of contact between tumor and vessel, and described as abutment, encasement, narrowing, or occlusion – Distinction between < 180° or 180° involvement of veins no longer as important with advent of venous reconstruction – SMV or splenic vein narrowing often results in mesenteric or gastroepiploic collateral veins ○ Tumor thrombus in mesenteric veins very uncommon, and much more common with neuroendocrine tumors • Pancreatic adenocarcinoma classically causes hypercoagulability: Look for evidence of incidental pulmonary emboli or deep venous thrombosis

MR Findings • Normal pancreas ○ Diffusely high signal intensity on T1WI ( liver) ○ Parenchyma variable in signal on T2WI ○ Pancreas enhances avidly and homogeneously on T1WI C+ (hyperintense to liver on arterial phase and isointense on delayed phase) • MR particularly helpful in identifying small group of tumors that are isodense to normal pancreas on CT • Tumor conspicuous on T1WI, appearing low signal and juxtaposed against high signal pancreatic parenchyma ○ Atrophic pancreas upstream from tumor often abnormally low signal on T1WI • T2WI generally not useful for tumor detection, as tumors often isointense to pancreas • Conspicuity on T1WI C+ similar to CT, with hypovascular tumors often demonstrating progressive delayed enhancement • Tumors often demonstrate restricted diffusion with lower ADC values than adjacent normal pancreas ○ DWI not helpful in differentiating tumors from other entities (such as autoimmune pancreatitis) • MRCP and T2WI can nicely demonstrate abrupt cutoff and obstruction of pancreatic and common bile ducts • MR generally 2nd choice (behind CT) for evaluating vascular involvement

Pancreas

TERMINOLOGY

Ultrasonographic Findings • Hypoechoic mass with only minimal internal color Doppler flow vascularity • Biliary dilatation and pancreatic ductal dilatation upstream from tumor • Endoscopic ultrasound: Similar to conventional US findings, with inferior accuracy compared to CECT for locoregional staging or determining vascular involvement ○ Helpful in excluding malignancy in patients with indeterminate CT findings ( negative predictive value) ○ Can help guide biopsy of pancreatic masses

Nuclear Medicine Findings • PET/CT ○ PET alone (without diagnostic CT) not effective for diagnosis of primary tumor (sensitivity as low as 72%) – Possible role in differentiating malignant from benign lesions, as FDG-avid lesions have risk of malignancy □ May help differentiate pancreatic adenocarcinoma, which shows avid focal uptake in mass, from focal autoimmune pancreatitis, which shows diffuse uptake throughout pancreas and within salivary glands – Effective in judging response to treatment (chemoradiation), whereas CT may not differentiate post-treatment fibrosis from residual tumor ○ PET not helpful for vascular involvement or locoregional staging (e.g., lymph nodes) due to poor spatial resolution ○ Helpful for distant staging, and may change resectability status of ~ 20% of patients compared to CECT

Radiographic Findings • Barium (upper GI) study ○ Frostberg 3 sign: "Inverted 3" contour to medial part of duodenal sweep 1035

Pancreas

Pancreatic Ductal Carcinoma ○ Spiculated duodenal wall with traction, fixation, and widening of duodenal sweep ○ Antral padding: Extrinsic indentation by tumor of posteroinferior margin of antrum • ERCP ○ Irregular, abrupt, nodular, rat-tailed, eccentric obstruction of pancreatic and common bile ducts ○ Double duct sign: Obstruction of pancreatic and common bile duct at same level

Imaging Recommendations • Best imaging tool ○ Dual-phase CECT with arterial and portal venous phases • Protocol advice ○ Best phase for identifying pancreatic cancers is pancreatic phase at ~ 40 seconds after contrast ○ Portal venous phase nearly equivalent for tumor detection and allows optimal evaluation of liver metastases and central mesenteric veins ○ Arterial phase critical for evaluating relationship of tumor to mesenteric arteries ○ Most institutions no longer acquire 3 phases, as arterial and portal venous phases are sufficient

DIFFERENTIAL DIAGNOSIS

Asymmetric Fatty Infiltration of Pancreatic Head • May superficially mimic tumor, but no mass effect, ductal dilatation, or other secondary signs of malignancy • MR with in- and out-of-phase imaging can easily make distinction between fatty infiltration and tumor

Tumors From Adjacent Organs • Duodenal adenocarcinoma or GI stromal tumors (GIST) involving distal stomach or duodenum may be difficult to distinguish from primary pancreatic mass

Groove Pancreatitis • Form of chronic pancreatitis affecting pancreaticoduodenal groove • Sheet-like, curvilinear soft tissue mass between pancreatic head and duodenum • Prospective diagnosis is very uncommon, and surgery often performed due to difficulty in differentiating from pancreatic or duodenal carcinoma

PATHOLOGY

Pancreatic Neuroendocrine Tumors

General Features

• Well-circumscribed mass that is typically markedly hypervascular on arterial phase images • Usually no ductal obstruction or parenchymal atrophy • Frequently calcify and may invade mesenteric veins with tumor thrombus (unusual features for pancreatic adenocarcinoma)

• Etiology ○ Risk factors: Cigarette smoking, alcohol, obesity, diabetes mellitus, chronic pancreatitis, high-fat diet • Genetics ○ Family history is strong risk factor, as ~ 10% of patients have 1st degree relative with pancreatic cancer ○ Activated KRAS oncogene in ~ 95% of cases ○ BRCA2 mutations (10% of patients), cholecystokinin B gene variant (35%), and several other genes associated • Associated abnormalities ○ Heritable syndromes associated with risk include – Hereditary pancreatitis, hereditary breast and ovarian cancer syndrome, Peutz-Jeghers, ataxia telangiectasia, familial colon cancer, Gardner syndrome, and familial aggregation of pancreatic cancer ○ High-risk groups may benefit from screening with CT, MR, or EUS

Focal Autoimmune Pancreatitis • Classic appearance is sausage-like diffuse enlargement of pancreas with peripheral peripancreatic "halo" • Can rarely manifest as focal hypodense pancreatic mass that may appear identical to adenocarcinoma • Upstream pancreas usually enlarged, rather than atrophic, and pancreatic duct usually not dilated • Typically responds dramatically to steroid therapy

Chronic Pancreatitis • May be associated with focal fibroinflammatory mass that can be indistinguishable from pancreatic cancer • Usually other stigmata of chronic pancreatitis, including diffuse atrophy of gland, dilated/beaded pancreatic duct with ductal calculi, and parenchymal calcifications • May obstruct both pancreatic and common bile ducts, producing double duct sign (similar to adenocarcinoma) • Given that chronic pancreatitis is a major risk factor, chronic pancreatitis and pancreatic adenocarcinoma may coexist

Pancreatic Metastases and Lymphoma • Hypovascular metastases (e.g., lung, colon) to pancreas may mimic pancreatic adenocarcinoma, but typically evidence of widespread metastatic disease elsewhere ○ Less commonly obstruct pancreatic duct or CBD • Lymphoma presents as homogeneous, hypoenhancing soft tissue mass ○ Almost never causes ductal obstruction/dilatation or parenchymal atrophy 1036

○ Usually occurs in setting of disseminated disease, with significant surrounding lymphadenopathy ○ Encases peripancreatic vessels without narrowing or occlusion

Staging, Grading, & Classification • Local staging ○ T1 tumor limited to pancreas 2 cm ○ T2 tumor limited to pancreas 2 cm ○ T3 tumor beyond pancreas but no celiac or SMA involvement ○ T4 tumor involves celiac or SMA • Determination of locoregional resectability (MD Anderson criteria) ○ Unequivocally resectable – No metastatic disease, suspicious lymphadenopathy distant from tumor, or vascular involvement of SMV, portal vein, celiac, hepatic artery, or SMA – Local lymph nodes immediately around tumor do not generally preclude surgical resection ○ Unresectable

Pancreatic Ductal Carcinoma

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most common symptoms are jaundice, weight loss (often severe), abdominal pain (usually epigastric pain radiating to back), and back pain – Jaundice common in pancreatic head tumors – Patients may present with Courvoisier gallbladder (distended palpable gallbladder due to obstruction) – Commonly asymptomatic until late in course, particularly body/tail tumors that do not cause jaundice – Rarely presents with unexplained migratory superficial thrombophlebitis (Trousseau syndrome) due to tumor induced hypercoagulability or bleeding from varices, which result from SMV or splenic vein occlusion ○ At presentation – Advanced local disease &/or metastases (65%) – Localized disease with spread to regional lymph nodes (21%) – Tumor confined to pancreas (14%) ○ Lab data – Elevated tumor markers: CA 19-9 (most important), CEA, CA 242 □ CA 19-9 levels often followed after surgery or therapy as marker of potential disease progression

Demographics • Age ○ Median age at onset: 71 years – Almost always after age 45 ○ Peak: 7th-8th decade • Gender ○ M:F = 1.3:1 • Ethnicity ○ African Americans > Caucasians • Epidemiology ○ 12th most common cancer and 4th leading cause of cancer deaths in USA – Lifetime risk of ~ 1.5% with 46,000 new cases each year ○ Accounts for 2-3% of all cancers ○ Most common malignant tumor of exocrine pancreas – Accounts for > 95% of pancreatic malignancies

Natural History & Prognosis • Only 15-20% of patients are candidates for surgery at time of presentation • 5-year survival rate is ~ 20% after surgery ○ Survival no better than chemoradiation alone if surgery performed for tumor found to be locally advanced at surgery ○ Surgical margins and node status at surgery are major prognostic indicators – Surgeon required to sample minimum number of nodes during surgery – Survival in node-negative disease after surgery may be as high as 30% • 5-year survival rate is < 5% without surgery with median survival of 3.5 months

Pancreas

– Distant metastatic disease or bulky lymphadenopathy distant from mass – > 180° involvement of SMA or > 180° involvement of celiac/hepatic artery without options for reconstruction – Occlusion of SMV or portal vein without options for reconstruction ○ Borderline resectable (definition may vary depending on author and institution) – 180° involvement of SMA – Short segment encasement or abutment of common hepatic artery near its origin with possibility of reconstruction at surgery – Short segment occlusion of SMV/portal vein with possibility of venous reconstruction

Treatment • Only potentially curative treatment for resectable tumor is complete surgical resection with negative surgical margins (R0 resection) ○ Pancreaticoduodenectomy (Whipple resection) for tumors of pancreatic head/uncinate, distal pancreatectomy for tumors of body/tail, and very rarely total pancreatectomy • Chemotherapy and radiation (external beam) utilized for resectable, borderline, and unresectable cancers ○ Gemcitabine and FOLFIRINOX are chemotherapy mainstays ○ Neoadjuvant chemoradiation often utilized prior to surgery in borderline resectable tumors • Palliative procedures include endoscopic biliary stenting (for jaundice), enteric stents or diverting gastrojejunostomy (for gastric/duodenal obstruction), and chemical splanchnicectomy or celiac nerve block to palliate abdominal pain

DIAGNOSTIC CHECKLIST Image Interpretation Pearls • Dilated pancreatic duct with abrupt cutoff and upstream atrophy, even in absence of visible mass, should be considered tumor until proven otherwise and requires further investigation (usually with endoscopic ultrasound)

Reporting Tips • Provide information that determines resectability, including presence of metastatic disease and involvement of major central mesenteric vasculature (portal vein, SMV, celiac, hepatic artery, and SMA)

SELECTED REFERENCES 1. 2. 3. 4.

Balachandran A et al: Imaging of pancreatic neoplasms. Surg Oncol Clin N Am. 23(4):751-88, 2014 Becker AE et al: Pancreatic ductal adenocarcinoma: risk factors, screening, and early detection. World J Gastroenterol. 20(32):11182-98, 2014 Loc WS et al: Novel strategies for managing pancreatic cancer. World J Gastroenterol. 20(40):14717-14725, 2014 Raman SP et al: Multimodality imaging of pancreatic cancer-computed tomography, magnetic resonance imaging, and positron emission tomography. Cancer J. 18(6):511-22, 2012

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Pancreas

Pancreatic Ductal Carcinoma

(Left) Coronal CECT demonstrates a poorly marginated hypodense mass in the pancreatic head/neck, typical of pancreatic adenocarcinoma. Note that the tumor involves the distal portal vein , portal/SMV confluence, and superior SMV. (Right) Coronal volume-rendered CECT in the same patient demonstrates that the mass has occluded the SMV over several centimeters extending from the confluence, with development of multiple collaterals and reconstitution of the SMV more inferiorly .

(Left) Coronal volumerendered CECT demonstrates a hypoenhancing mass in the pancreatic head, found to be a pancreatic cancer at resection. The lack of parenchymal atrophy or ductal dilatation is unusual for pancreatic cancer. (Right) Axial CECT demonstrates hypodense enlargement of the entire pancreas , representing infiltration by pancreatic adenocarcinoma. Although uncommon, pancreatic cancer can rarely diffusely involve the entire gland, and may be confused for autoimmune pancreatitis.

(Left) Coronal CECT demonstrates a pancreatic cancer involving the adjacent duodenum, resulting in duodenal obstruction and dilatation . Note that the tumor involves roughly a 180° circumference of the SMA . (Right) Coronal CECT demonstrates a pancreatic cancer obstructing the pancreatic duct and causing upstream parenchymal atrophy. Note that the mass directly invades the adjacent duodenum . Multiple liver metastases are present, precluding resection.

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Pancreatic Ductal Carcinoma Pancreas

(Left) Transverse ultrasound demonstrates a hypoechoic mass in the pancreatic body, representing a pancreatic adenocarcinoma. Ultrasound is generally quite limited in assessment of the pancreas due to overlying bowel gas. (Right) Color Doppler ultrasound of the pancreatic head demonstrates a hypoechoic, poorly marginated pancreatic adenocarcinoma . Note the relatively minimal internal color flow vascularity within the mass, typical of these lesions on ultrasound.

(Left) ERCP in a patient with a pancreatic head adenocarcinoma demonstrates an irregular stricture of the common bile duct. The abrupt, irregular narrowing of the duct at the stricture certainly is a highly suspicious feature for malignancy. (Right) Coronal MRCP with MIP reconstruction demonstrates the typical double duct sign associated with pancreatic cancer, with abrupt occlusion of the pancreatic duct and common bile duct at the level of the patient's pancreatic head mass.

(Left) Axial T1WI C+ FS MR demonstrates a hypoenhancing mass in the pancreatic head, compatible with pancreatic adenocarcinoma. The appearance of pancreatic cancer on post-gadolinium MR images is comparable to its appearance on CECT. (Right) Axial ADC map in the same patient demonstrates significant restricted diffusion within the mass. Restricted diffusion can be a valuable tool to help increase the conspicuity of subtle pancreatic cancers.

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Pancreas

Pancreatic Ductal Carcinoma

(Left) Axial CECT in a patient with pancreatic cancer demonstrates peripherally enhancing metastases throughout the liver. The liver is almost always the 1st site of distant metastasis for pancreatic adenocarcinoma. (Right) Axial CECT demonstrates an infiltrative, hypodense mass in the pancreatic tail, in keeping with pancreatic adenocarcinoma. Pancreatic tail cancers typically do not involve vital vasculature and often come to attention later than pancreatic head cancers due to lack of jaundice.

(Left) Coronal CECT demonstrates an infiltrative hypodense mass in the pancreatic head with upstream pancreatic ductal dilatation . The mass encases and severely narrows the SMV . (Right) Coronal volume-rendered CECT in the same patient demonstrates severe narrowing of the SMV, with the development of large venous collaterals . The presence of venous collaterals in a pancreatic cancer patient should always suggest the presence of venous narrowing or occlusion.

(Left) Axial curved MINIP display shows upstream dilatation of the pancreatic duct proximal to a focal structure in the pancreatic duct. (Right) Endoscopic ultrasound of the strictured area reveals a solid mass that was biopsied and shown to be adenocarcinoma. Any focal stricture of the main pancreatic duct should be considered as an isodense carcinoma until proven otherwise, and should lead to EUS interrogation and biopsy.

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Pancreatic Ductal Carcinoma Pancreas

(Left) Axial T1 noncontrast MR demonstrates a hypointense uncinate process mass nicely juxtaposed against the T1 hyperintense normal pancreatic parenchyma . Noncontrast T1 images tend to be more helpful than T2WI for pancreatic adenocarcinoma identification. (Right) Coronal T2 MR demonstrates the relative lack of conspicuity of the same tumor on T2WI. The lesion is relatively hypointense, and is difficult to differentiate from the adjacent hypointense normal pancreatic parenchyma .

(Left) Axial T1 C+ FS MR demonstrates a poorly marginated, hypoenhancing mass in the pancreatic tail extending into the splenic hilum and invading the spleen. (Right) Axial T2 MR in the same patient demonstrates that the mass is mildly T2 hyperintense. In general, pancreatic adenocarcinoma is often isointense or only mildly hyperintense on T2WI, making this pulse sequence unreliable for tumor detection.

(Left) Axial T1 FS C+ MR in the arterial phase demonstrates a hypodense mass in the pancreatic tail, compatible with pancreatic adenocarcinoma. Several metastases are present in the liver. (Right) Axial FS T1 C+ MR in the delayed phase from the same patient shows that the mass now demonstrates considerable delayed enhancement. Delayed enhancement, which is much easier to appreciate on MR compared to CT, is a fairly common feature of pancreatic adenocarcinoma.

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Pancreas

Mucinous Cystic Pancreatic Tumor KEY FACTS

• Unilocular or multilocular pancreatic cystic tumor composed of large, mucinous cysts and containing ovarian stroma

○ No apparent communication with main pancreatic duct • MR: Usually simple fluid signal (high T2; low T1), but may be slightly less T2 hyperintense due to mucin content ○ MRCP: No communication with main pancreatic duct

IMAGING

PATHOLOGY

• Strong tendency to occur in body and tail of pancreas • Often very large (bigger on average than intraductal papillary mucinous neoplasm [IPMN] or serous cystadenoma) • CT: Unilocular/multilocular cyst with internal septations ○ "Macrocystic" pattern: Few (< 6) macrocystic locules, which are relatively large (> 2 cm) ○ Usually of simple fluid attenuation, but may be mildly hyperdense due to hemorrhage or protein ○ Frequent peripheral curvilinear calcifications or calcifications in septations (16% of cases) ○ Presence of thick wall, mural nodularity, or thick septations suggests invasive malignancy

• Tumor shares clinical and pathologic characteristics of biliary tumors, ovarian tumors, and IPMN • Presence of ovarian stroma lining cyst is key feature for diagnosis of mucinous cystic neoplasm (MCN)

TERMINOLOGY

(Left) Graphic of a mucinous cystic tumor shows a multiseptate, mucin-filled, cystic mass in the pancreatic tail that displaces the pancreatic duct. (Right) Axial CECT in a 35-year-old woman demonstrates a large complex cystic mass arising from the pancreatic tail with multiple internal cystic locules and septations, some of which are thick . This mass was found to be a mucinous cystic neoplasm (MCN) with invasive adenocarcinoma at surgery.

(Left) Axial CECT in a 46-yearold woman demonstrates a large, simple-appearing cyst arising from the upstream pancreatic body. (Right) Axial T2 FS MR in the same patient confirms the lack of complexity within the T2hyperintense cyst . MR can sometimes show complexity and suspicious features that might be difficult to identify on CT. This was found to be a MCN with low-grade dysplasia at surgery.

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CLINICAL ISSUES • Strong preponderance in middle-aged women (99%) • Considered premalignant or frankly malignant: Rate of malignancy in different series ranges between 10-40% • Risk factors for invasive malignancy: Older age, lesion size, mural nodularity, thick wall, patient symptoms (pain, pancreatitis), and CEA and CA 19-9 • MCNs typically undergo complete surgical resection with adjuvant chemotherapy for malignant lesions

Mucinous Cystic Pancreatic Tumor

Synonyms • Mucinous cystic neoplasm (MCN), mucinous macrocystic neoplasm or adenoma, mucinous cystadenoma or cystadenocarcinoma

Definitions • Thick-walled, unilocular or multilocular pancreatic tumor composed of large, mucin-containing cysts • MCN and intraductal papillary mucinous neoplasm (IPMN) are together classified as pancreatic mucinous tumors

IMAGING General Features • Best diagnostic clue ○ Large, unilocular or multilocular encapsulated cystic mass with septations and thick wall in pancreatic tail • Location ○ Tail of pancreas (more common) ○ Presents as single lesion (not multifocal like IPMN) • Size ○ 2-12 cm in diameter – MCNs usually larger than serous cystadenoma or IPMN ○ Size is predictor of biologic behavior – Lesions < 40 mm found to have low risk of malignancy in recent series • Morphology ○ Typically round/ovoid, but may be ill defined/irregular

CT Findings • Unilocular or multilocular encapsulated cyst in pancreatic body/tail with frequent internal septations ○ "Macrocystic" pattern: Few (< 6) macrocystic locules that are relatively large (> 2 cm) • Usually of simple fluid attenuation, but may be mildly hyperdense due to hemorrhage or protein • Frequent peripheral curvilinear calcifications or calcifications in septations (16% of cases) • Presence of thick, irregular wall, internal mural nodularity, or thick septations suggest invasive malignancy ○ Upstream pancreatic ductal dilatation or atrophy suggest invasive malignancy • No apparent communication with main pancreatic duct ○ In rare instances, some series have suggested possible communication with pancreatic duct in very small minority of lesions

MR Findings • Typically show simple fluid signal (high T2; low T1), but may be slightly less T2 hyperintense due to mucin content ○ May show areas of T1 hyperintensity due to internal hemorrhage, proteinaceous content, or mucin • Internal septations (typically T2 hypointense) easier to perceive on MR compared to CT • Calcifications often not visible on MR: If visible, are low signal on all pulse sequences • Thick, enhancing septations, wall thickening, and mural nodularity on T1WI C+ suggest invasive malignancy • MRCP: No communication with pancreatic duct

• DWI: No role in differentiating mucinous from nonmucinous lesions or benign from malignant

Ultrasonographic Findings

Pancreas

TERMINOLOGY

• Grayscale ultrasound ○ Multiloculated cystic mass with echogenic internal septa – Often associated with thick wall ± mural nodularity ○ Can also appear as unilocular anechoic mass

Imaging Recommendations • CECT or MR

DIFFERENTIAL DIAGNOSIS Pancreatic Pseudocyst • Usually known history of pancreatitis or alcoholism ± imaging stigmata of chronic pancreatitis (pancreatic calcifications, ductal beading, etc.) • Loculated cyst with adjacent peripancreatic fat stranding/inflammation • Evolves over time from acute peripancreatic fluid collection into loculated pseudocyst • Communication with pancreatic duct is frequent (70% of cases) and may be visible on ERCP or MRCP • Lab data: Increased amylase in cyst and serum • When occurring in pancreatic tail, may simulate unilocular mucinous cystic neoplasm

Pancreatic Serous Cystadenoma • Well-circumscribed, lobulated cystic mass most often occurring in pancreatic head • Classic appearance ("microcystic" or "sponge" lesion): Many small cysts separated by thin septa and with central scar demonstrating calcification ○ Calcification more common in serous than mucinous pancreatic neoplasms (38% vs. 16%) • Macrocystic, oligocystic, and unilocular variants of serous cystadenoma difficult to distinguish from MCN ○ Thick wall and mural nodularity unusual with serous cystadenoma

Pancreatic IPMN • Mucin-producing neoplasms which are classified into 3 types with different risks of malignancy ○ Side-branch IPMN: Arise in pancreatic duct side branch and carry risk of invasive malignancy of 17% ○ Main pancreatic duct (MPD): Arise in main pancreatic duct and carry high risk of malignancy (58%) ○ Combined type IPMN: Features of both side branch and main duct IPMN with prognosis similar to main duct IPMN • Side-branch or combined type IPMN: Cyst (± nodularity, septations, calcifications) that communicates with pancreatic duct

Cystic Pancreatic Neuroendocrine Tumor • Cystic neuroendocrine tumors more likely to be non-insulin producing and nonsyndromic • Cystic lesion without pancreatic ductal dilatation or atrophy ○ Differentiate from IPMN/MCN by presence of peripheral hyperenhancement on arterial phase CECT or MR

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Pancreas

Mucinous Cystic Pancreatic Tumor

Pancreatic Epithelial (True) Cyst • Usually small and multiple nonenhancing cysts without pancreatic ductal dilatation • Rare lesions most commonly seen in patients with von Hippel-Lindau and autosomal dominant polycystic kidney disease

Lymphangioma (Mesenteric Cyst) • Water density cyst with imperceptible wall and internal thin septations • May abut pancreas mimicking pancreatic cystic neoplasm

Lymphoepithelial Cyst • Rare benign cystic lesion that abuts and protrudes into pancreas mimicking pancreatic cystic lesion • Well-defined water density cyst most commonly seen in pancreatic body or tail • May be unilocular or multilocular ± internal septations and fat density

PATHOLOGY General Features • Tumor shares clinical and histopathologic characteristics of biliary tumors, ovarian tumors, and IPMN ○ WHO classification emphasizes ovarian stroma lining cyst to be key feature for diagnosis of MCN

Gross Pathologic & Surgical Features • Large mass encapsulated by thick fibrous capsule • Smooth and round, but may have lobulated surface • Cut section: Multilocular or unilocular large cysts ○ Individual cystic components measure > 2 cm with thin septations < 2 mm • Cystic cavity may be filled with thick mucoid material and clear, green, or blood-tinged fluid • Solid papillary projections protruding into interior of tumor are sign of invasive malignancy

CLINICAL ISSUES

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• Diagnosis based on a combination of preoperative imaging (CT or MR), endoscopic ultrasound with cyst aspiration/cytology/tumor markers, and post-operative histopathologic analysis

Demographics • Age ○ Mean: 50 years (range: 20-95 years) – 50% between 40-60 years • Gender ○ M:F = 1:99 ○ Termed "mother" tumor due to predisposition for middle-aged females • Epidemiology ○ Less common than IPMN and serous cystadenomas ○ 25% of all resected pancreatic cysts

Natural History & Prognosis • Considered premalignant or frankly malignant ○ Range from adenomas to invasive carcinoma (depending on degree of atypia) ○ Malignant MCNs are lesions containing high-grade dysplasia or invasive carcinoma ○ Even benign MCNs carry potential for malignant transformation and are considered premalignant • Because almost all MCNs are resected, true natural history not completely certain: Rate of malignancy in different series ranges between 10-40% • Overall 5-year survival of MCNs is 98% for benign lesions and 62% for lesions with high-grade dysplasia or invasive carcinoma • Major risk factors for invasive malignancy ○ Older patient age, larger lesion size, mural nodularity, thick wall, peripheral calcification, patient symptoms (pain, pancreatitis, etc.), and elevated CEA/CA 19-9 • Completely excised in patients with benign MCN: Excellent prognosis with extraordinarily low risk of recurrent disease • Incompletely excised, marsupialized, or drained: Poor prognosis

Presentation

Treatment

• Most common signs/symptoms ○ Many MCNs are asymptomatic and incidentally discovered ○ May present with epigastric pain, recurrent pancreatitis (10%), palpable mass (12%), or mass effect on adjacent structures (bowel obstruction, gastric outlet obstruction, jaundice) ○ Rarely presents with local invasion/distant metastases ○ Very rarely presents with systemic manifestations caused by tumor production of gastrin or other hormones • Lab data ○ Increased levels of serum and cyst fluid CEA ○ Increased cyst fluid levels of CA 19-9 (80% of cases) and CA 72-4 ○ Low amylase levels • Biopsy: Invasive cancer and benign epithelium can coexist in same lesion, making biopsy unreliable; benign biopsy result does not exclude malignancy

• Traditionally all MCNs have undergone complete surgical excision (usually distal pancreatectomy and splenectomy) ○ Lesions in poor surgical candidates may be conservatively managed with close serial imaging follow-up • Benign MCNs with complete surgical resection do not require further treatment or follow-up • Malignant MCNs receive adjuvant chemotherapy after surgical resection

DIAGNOSTIC CHECKLIST Consider • Differentiation from other cystic pancreatic lesions may not be possible based on CT/MR alone, and may require cyst aspiration with cytology and tumor markers

SELECTED REFERENCES 1.

Park JW et al: Mucinous cystic neoplasm of the pancreas: is surgical resection recommended for all surgically fit patients? Pancreatology. 14(2):131-6, 2014

Mucinous Cystic Pancreatic Tumor Pancreas

(Left) Axial CECT in a 38-yearold woman demonstrates a large complex cystic mass extending exophytically downwards from the pancreatic tail with multiple septations and enhancing mural nodularity . (Right) Coronal CECT in the same patient demonstrates the large size of the mass, as well as the presence of extensive septations and mural enhancing soft tissue , both of which raise suspicion for malignancy. This was found to be a MCN with high-grade dysplasia at surgery.

(Left) Axial CECT in a 34-yearold woman demonstrates a simple unilocular cyst in the pancreatic tail, found to be a MCN with low-grade dysplasia at surgery. There is no mural nodularity or a thickwall to suggest invasive malignancy. (Right) Axial CECT shows a large cystic mass arising from the pancreatic body. The mass has large cystic spaces separated by septa . Also noted are peripheral calcification and soft tissue mural nodularity . This is the classic imaging presentation of MCN.

(Left) Axial CECT in a 61-yearold woman demonstrates a cystic lesion in the pancreatic tail with coarse mural calcification . (Right) Axial T2 MR in the same patient better demonstrates the presence of internal septations within the T2hyperintense cyst . MCN with low-grade dysplasia was found at surgery.

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Pancreas

Mucinous Cystic Pancreatic Tumor

(Left) Axial CECT in a 34-yearold woman demonstrates a simple-appearing cyst arising from the pancreatic tail. No internal complexity is visualized. (Right) Axial T1 MR in the same patient demonstrates layering T1hyperintense blood products within the cyst, representing a hematocrit level. The presence of hemorrhage within an MCN is quite unusual.

(Left) Coronal volumerendered CECT demonstrates a pancreatic cystic mass with prominent peripheral rim-like calcification . Calcifications are seen in roughly 16% of MCNs. (Right) Axial CECT demonstrates a large complex cystic mass arising from the pancreatic tail with multiple internal septations and solid mural nodularity . The complexity of the lesion raises suspicion for malignancy, which was confirmed after surgery where an MCN with invasive carcinoma was found.

(Left) Axial T2 FS MR demonstrates a large cystic mass arising from the pancreatic tail with innumerable internal T2hyperintense cystic locules . (Right) Axial T2 MR in the same patient demonstrates that the large cystic mass has layering debris with a fluidfluid level , probably representing old blood products or proteinaceous debris. This was found to be an MCN with invasive carcinoma at resection.

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Mucinous Cystic Pancreatic Tumor Pancreas

(Left) Axial CECT in a 33-yearold woman shows a cystic mass with internal septations originating from the tail of the pancreas. There is a single mural nodule . At surgery, a benign MCN was resected with no evidence of adenocarcinoma. (Right) Axial CECT shows a large, complex cystic pancreatic body mass with internally enhancing soft tissue . EUS-guided biopsy revealed mucinous adenocarcinoma. The presence of enhancing soft tissue within the cyst is strongly suspicious for malignancy.

(Left) Axial CECT in a 50-yearold man with vague abdominal pain shows a large complex cystic mass in the body/tail segment of the pancreas. Note the septa and the large cystic spaces within the mass. (Right) Gross pathology from the same case shows that the resected mass was full of mucinous fluid and had thickened septa. Histologic exam showed cellular atypia, and the lesion was considered a low-grade malignancy.

(Left) Axial CECT shows a cystic mucinous tumor in the pancreatic tail, with a few large cystic spaces separated by visible septa, as well as focal calcifications . (Right) Coronal MRCP shows a cystic mucinous tumor in the pancreatic tail with a few cystic spaces and septa. The pancreatic duct is deviated but otherwise normal.

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Pancreas

Pancreatic IPMN KEY FACTS

TERMINOLOGY • Mucin-producing papillary tumor arising from epithelium of main pancreatic duct (MPD) or duct side branches

IMAGING • Side branch IPMN ○ Well-defined cystic lesion with variable morphology: Unilocular, multicystic, or tubular ○ Communication with adjacent main pancreatic duct is key to diagnosis (may be more visible on MR than CT) ○ Dilatation of adjacent main pancreatic duct should raise concern for main duct involvement ○ Multiplicity is strong clue to diagnosis: Often multiple small cysts scattered throughout pancreas • Main duct IPMN ○ Markedly dilated, tortuous MPD often with bulging ampulla filled with fluid (mucin) ○ Dilatation may be segmental or diffuse ○ Polypoid nodularity in MPD suspicious for malignancy

(Left) Graphic shows combined main and side branch IPMN with gross dilatation of all ducts by mucin, which pours out of a bulging papilla into the duodenum. The parenchyma in the pancreatic head is atrophic. (Right) Coronal MRCP with MIP reconstruction nicely demonstrates 2 discrete side branch IPMNs and their direct connection with the adjacent normal sized pancreatic duct.

(Left) Coronal MRCP with MIP reconstruction demonstrates multiple cysts throughout the pancreas compatible with multiple side branch IPMN. Multifocality is characteristic of IPMN, and multiple discrete cystic lesions are often present in the same patient. (Right) Coronal CECT demonstrates innumerable pancreatic cysts, compatible with multiple side branch IPMN. No suspicious individual cyst or solid mass was seen, but EUS findings were suspicious, and the patient was found to have invasive carcinoma at surgery.

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○ Amorphous calcifications may be seen within duct ○ Pancreas often atrophic overlying dilated duct • Combined IPMN ○ Cystic lesion in contiguity with dilated MPD (shares imaging features of main duct and side branch IPMN)

CLINICAL ISSUES • EUS cyst aspiration: Elevated cyst fluid CEA (> 192 ng/mL) • Most patients asymptomatic (incidental imaging finding), but can result in repetitive bouts of pancreatitis • Risk of transformation into invasive carcinoma, with main duct involvement associated with risk of malignancy • Management of IPMN based on 2012 IAP guidelines ○ Worrisome features: Cyst size 3 cm, MPD dilatation 5-9 mm, peripheral wall thickening, nonenhancing mural nodularity, abrupt change in main duct caliber with upstream pancreatic atrophy ○ High-risk features: MPD dilatation 1 cm, enhancing solid mural nodularity, or biliary obstruction

Pancreatic IPMN

Abbreviations • Intraductal papillary mucinous neoplasm (IPMN)

Definitions • Mucin-producing papillary tumor arising from epithelium of main pancreatic duct (MPD) or pancreatic duct side branches

IMAGING General Features • Best diagnostic clue ○ Side branch type: Cystic lesion with direct communication with adjacent MPD on CECT/MRCP ○ MPD type: Dilated MPD with bulging papilla and enhancing soft tissue nodularity within duct lumen • Location ○ Side branch lesion: Predisposition for uncinate process and head, but can occur anywhere in pancreas ○ MPD lesion: Either diffuse or segmental involvement of pancreatic duct, but most often involves body and tail

CT Findings • Side branch IPMN ○ Well-defined cystic lesion with variable morphology: Unilocular, multicystic (with grape-like clusters or tubes and arcs), or tubular ○ Communication with adjacent MPD is key to diagnosis, but may not always be possible to demonstrate – May be more apparent on multiplanar reformations – Dilatation of adjacent main pancreatic duct should raise concern for main duct involvement ○ Multiplicity is strong clue to diagnosis: Often multiple small cysts scattered throughout pancreas ○ Calcifications in 20%, but no correlation with malignancy • Main duct IPMN ○ Markedly dilated, tortuous MPD without evidence of distal obstructing mass and often with "bulging" ampulla filled with fluid (mucin) at duodenal sweep – Dilatation may be segmental or diffuse – Possibility of main duct IPMN should be considered when duct measures 5 mm ○ Presence of polypoid enhancing nodularity within MPD lumen is very suspicious for malignancy ○ Amorphous calcifications may be seen within duct ○ Pancreas often atrophic overlying dilated duct • Combined IPMN ○ Cystic lesion in contiguity with dilated MPD (shares imaging features of main duct and side branch IPMN) • Concerning imaging features based on 2012 International Association of Pancreatology (IAP) guidelines ○ Worrisome features: Cyst size 3 cm in any dimension, MPD dilatation between 5-9 mm, peripheral wall thickening or enhancement, nonenhancing mural nodularity, abrupt change in main duct caliber with distal pancreatic atrophy, lymphadenopathy ○ High-risk features: MPD dilatation 1 cm, enhancing solid mural nodularity, or biliary obstruction

MR Findings • Little data directly comparing CT and MR, but MR likely superior for identifying small cysts and multifocal disease, visualizing communication between cyst and main duct, and assessing main duct involvement ○ Superior soft tissue resolution of MR may allow better assessment of subtle mural nodularity • Side branch IPMN typically hyperintense on T2WI and low signal on T1WI, and can appear unilocular, multicystic, tubular, or as grape-like cluster of cysts ○ Presence of dilated adjacent main pancreatic duct concerning for main duct involvement – MRCP may be more accurate than CT for assessing main duct size and internal mural nodularity • Direct communication with main pancreatic duct easier to identify on thin-section 3D MRCP images ○ Enlargement of cyst following administration of secretin may be secondary sign of communication with main duct • Malignant IPMN may have lower ADC values on DWI compared to benign IPMN, but not widely clinically utilized (due to overlap in ADC values)

Pancreas

TERMINOLOGY

Ultrasonographic Findings • Conventional ultrasound lacks spatial resolution to identify high-risk or worrisome imaging features • Endoscopic ultrasound (EUS): Now considered important part of evaluation of pancreatic cysts in specialized centers ○ Spatial resolution of EUS may help identify suspicious morphologic features (e.g., mural nodularity) not visible on CT/MR, and can help guide FNA and cyst aspiration – May identify communication between cyst and MPD ○ 2012 IAP guidelines recommend EUS with cyst aspiration for cysts with worrisome imaging features – Cyst size 3 cm, MPD dilatation 5-9 mm, peripheral wall thickening, nonenhancing mural nodularity, etc.

Radiographic Findings • ERCP ○ Direct visualization of patulous, bulging, "fish-mouth" ampulla with mucin extruding through ampulla (due to mucin hypersection) in main duct IPMN ○ Can directly demonstrate dilatation of MPD (in main duct IPMN) or communication of side branch IPMN with MPD ○ Filling defects within duct (either nodular or band-like) may represent mucin or papillary tumors

Imaging Recommendations • Best imaging tool ○ MR or CECT are best initial noninvasive modalities

DIFFERENTIAL DIAGNOSIS Chronic Pancreatitis • Dilated, beaded, irregular main pancreatic duct with intraductal calculi and parenchymal atrophy/calcifications • Significant imaging/clinical overlap with main duct IPMN

Pancreatic Ductal Carcinoma • Hypodense mass with abrupt cutoff of pancreatic duct and upstream MPD dilatation/parenchymal atrophy • Small occult lesion obstructing MPD may appear identical to main duct IPMN 1049

Pancreas

Pancreatic IPMN

Pancreatic Pseudocyst • Cystic lesions that may communicate with MPD and can mimic side branch IPMN • Usually known clinical history of pancreatitis (or risk factors) and inflammatory changes surrounding cyst

Mucinous Cystic Pancreatic Tumor • Cyst (± thick wall) most often occurring in pancreatic body/tail in middle-aged female • Unilocular or oligocystic with no MPD communication

Pancreatic Serous Cystadenoma • Classic microcystic lesions appear sponge-like and are composed of multiple tiny cysts (± central calcification) • No demonstrable communication with MPD

PATHOLOGY General Features • Etiology ○ Pathogenesis: Follows adenoma-carcinoma sequence – Hyperplasia of columnar epithelial cells lining ducts dysplasia and proliferation to form papillary projections papillary projections protrude into and expand branch ducts (BPD) and MPD excessive mucin production, obstruction, and dilatation of BPD/MPD • Genetics ○ Several known associated gene mutations including KRAS (~ 50% of cases)

Staging, Grading, & Classification • IPMN can be divided into 3 types ○ Side branch IPMN: Mucin-producing neoplasm centered in pancreatic duct side branch with normal MPD – Variable risk of malignancy: ~ 25% contain high-grade dysplasia and ~ 17% contain invasive carcinoma ○ Main duct IPMN: Mucin-producing neoplasm centered in main pancreatic duct – High risk of malignancy: ~ 62% contain high-grade dysplasia and ~ 58% contain invasive carcinoma ○ Combined IPMN: Involves both main duct and side branch with malignancy risk similar to main duct IPMN • WHO classification separates IPMN into 4 categories ○ IPMN with low-grade dysplasia (previously adenoma) ○ IPMN with intermediate-grade dysplasia (previously borderline) ○ IPMN with high-grade dysplasia (previously carcinoma in situ) ○ IPMN with invasive carcinoma ○ High-grade dysplasia or invasive carcinoma considered true malignancy

Microscopic Features • Histologic subtypes based on mucosal lining: Gastric, intestinal, pancreatobiliary, oncocytic, and tubular subtypes

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Majority of patients asymptomatic (incidental finding) 1050

○ Usually nonspecific symptoms: Abdominal pain, weight loss, nausea, vomiting ○ Obstruction of MPD with mucin can result in repetitive bouts of pancreatitis or exocrine/endocrine insufficiency • Lab data ○ EUS-guided cyst aspiration: Elevated cyst fluid CEA (> 192 ng/mL), positive mucin stain ○ Amylase/lipase may be elevated due to pancreatitis ○ Elevated CEA and CA 19-9 concerning for malignancy

Demographics • Age ○ Presentation usually between 50-70 years • Gender ○ Possible slight male predominance • Epidemiology ○ True incidence unclear, as lesions are usually (and increasingly) identified incidentally on CT or MR – IPMN accounts for 20-50% of all pancreatic cysts ○ More common in familial pancreatic cancer, PeutzJeghers, and familial adenomatous polyposis

Natural History & Prognosis • Most lesions are asymptomatic, incidental findings, but can result in recurrent attacks of acute and chronic pancreatitis • Risk of transformation into invasive carcinoma ○ risk of invasive carcinoma distant from primary lesion suggests entire ductal epithelium may be predisposed to development of atypia (field defect theory) ○ Presence of multiple IPMN may also be associated with risk of invasive carcinoma

Treatment • Management of IPMN based on 2012 IAP guidelines ○ High-risk features (MPD 1 cm, enhancing mural nodularity, or biliary obstruction) warrant resection ○ Lesions with worrisome features (cyst size 3 cm, MPD dilatation between 5-9 mm, nonenhancing mural nodularity, abrupt change in main duct caliber with distal pancreatic atrophy) should undergo EUS – Presence of suspicious cytology or mural nodularity/main duct involvement on EUS in this subgroup warrants consideration of surgery – If EUS is negative, follow up with CT/MR based on size (2-3 years for cysts < 1 cm, yearly x 2 years for 1-2 cm, and 3-6 months for > 2 cm) ○ For lesions without worrisome imaging features, follow up based on size as above (surgery often considered for cysts measuring 3 cm in young patients) ○ Cysts may be resected regardless of worrisome features or size if patient is symptomatic ○ Surgery depends on cyst location and extent of MPD involvement: Whipple, distal pancreatectomy, or total pancreatectomy – If multiple cysts, most suspicious often resected and other lesions observed

SELECTED REFERENCES 1.

Campbell NM et al: Imaging patterns of intraductal papillary mucinous neoplasms of the pancreas: An illustrated discussion of the International Consensus Guidelines for the Management of IPMN. Abdom Imaging. ePub, 2014

Pancreatic IPMN Pancreas

(Left) Axial CECT demonstrates a cystic lesion in the pancreatic head. Note the soft tissue around the margins of the cyst, as well as its communication with a dilated pancreatic duct . This was found to be an IPMN with invasive carcinoma and main duct involvement at surgery. (Right) Coronal volume-rendered CECT demonstrates a complex cystic mass in the pancreatic head with multiple septations, mural nodularity, and obstruction of the CBD. This was found to be an IPMN with invasive carcinoma.

(Left) Axial T2 FS MR demonstrates diffuse severe dilatation of the MPD, with associated pancreatic parenchymal atrophy. (Right) Coronal MRCP with MIP reconstruction better demonstrates the severe dilatation of the entire MPD as well as marked cystic dilatation of innumerable side branches. Frank mucin was seen extruding from the duct on ERCP, and this was found to represent a main duct IPMN with invasive carcinoma.

(Left) Axial CECT demonstrates a profoundly dilated MPD with amorphous calcifications in the center of the duct and clear enhancing intraductal soft tissue . The pancreatic parenchyma is severely atrophic. (Right) Axial CECT in the same patient shows a large cystic mass inferior to the pancreas directly contiguous with the dilated pancreatic duct. Note the large amount of enhancing soft tissue within the mass. This was found to represent a mixed-type IPMN with invasive colloid carcinoma at surgery.

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Pancreas

Pancreatic IPMN

(Left) Coronal CECT demonstrates a diffusely dilated MPD . Note the presence of subtle enhancing soft tissue within the duct. (Right) Axial CECT from the same patient demonstrates multiple discrete enhancing nodules within the downstream duct, a highly suspicious feature for malignancy. This was found to be a main duct IPMN with invasive carcinoma at surgery.

(Left) Axial CECT shows multiple calcifications within a markedly dilated pancreatic duct . (Right) Axial volumerendered CECT in the same patient shows that the calcifications are associated with soft tissue masses within the massively dilated pancreatic duct. At surgery the calcifications were due to invasive mucinous adenocarcinoma from a main duct IPMN.

(Left) Axial CECT shows focal dilatation of the MPD in the tail of the pancreas . (Right) Axial CECT at a more caudal level in the same patient shows extensive mucinous material filling the lesser sac . At surgery a ruptured IPMN was found with mucinous debris in the lesser sac.

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Pancreatic IPMN Pancreas

(Left) Axial CECT with curved planar reformation shows a diffusely dilated MPD with a bulging ampulla , a characteristic feature of main duct IPMN. (Right) Axial CECT demonstrates a markedly dilated MPD that contains intraductal solid tissue characteristic of a malignant main duct IPMN.

(Left) Axial minimum-intensity projection image (MinIP) from a CECT shows a cystic lesion connected by a side branch to the MPD . These findings are diagnostic of a side branch IPMN. (Right) ERCP in the same patient demonstrates the side branch IPMN and confirms its communication with the adjacent main pancreatic duct .

(Left) Axial CECT demonstrates gross dilation of the entire pancreatic duct , with diffuse atrophy of the pancreatic parenchyma, a characteristic constellation of findings for a main duct IPMN. (Right) Endoscopic photograph in the same patient shows a gaping ampulla with clear mucin pouring from the orifice, a classic finding in main duct IPMN due to mucin hypersecretion by the tumor.

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Pancreas

Pancreatic Neuroendocrine Tumors KEY FACTS

IMAGING

CLINICAL ISSUES

• Well-circumscribed pancreatic mass with sharply defined, noninfiltrative margins ○ Syndromic tumors: Small in size (usually < 3 cm) ○ Nonsyndromic tumors usually much larger (> 5 cm) with frequent cystic and necrotic degeneration • Usually avidly enhancing on arterial phase images and less conspicuous on venous phase • Lesions frequently calcify (unlike adenocarcinoma) • May invade mesenteric veins with tumor thrombus • Do not usually obstruct biliary/pancreatic ducts unless large • Cystic NET can mimic other cystic neoplasms ○ Peripheral rim of enhancement or hypervascular mural nodularity should suggest correct diagnosis • Hypervascular lymph node and liver metastases ○ Fluid-fluid levels within liver metastases specific for NET ○ Liver metastases often very T2 hyperintense on MR and can mimic cysts or hemangiomas

• Divided into syndromic (produce clinical syndrome with abnormal lab findings) or nonsyndromic tumors • Most common syndromic tumors include insulinoma, glucagonoma, gastrinoma, somatostatinoma, VIPoma ○ Insulinoma: Usually solitary and benign (90%) – Presents with Whipple triad (hypoglycemia, low fasting glucose, and relief by IV glucose) ○ Gastrinoma: Often multiple, malignant (60%), and associated with MEN1 – Presents with Zollinger-Ellison syndrome: Severe peptic ulcer disease, increased acidity, and diarrhea • Treatment ○ Somatostatin analogs (such as Octreotide) provide symptom relief for syndromic tumors ○ Surgical resection (enucleation or pancreatectomy), chemoembolization or resection of liver metastases, chemotherapy, and watchful waiting are possible treatment options

(Left) Axial CECT of an insulinoma in the arterial phase shows a subcentimeter hypervascular mass in the pancreatic tail. (Right) Gross pathology from the same patient shows the resected specimen confirmed to be a neuroendocrine tumor (NET) , with its typical wellcircumscribed, noninfiltrative appearance. NETs are often referred to by their main hormonal output (e.g., insulinoma), but pathologists call them NETs because of the electron microscopic finding of neuron-specific enolase.

(Left) Axial CECT in a patient with a metastatic nonsyndromic NET shows a large hypervascular pancreatic mass and additional hepatic metastases . This constellation of findings is typical of a malignant NET of the pancreas, a glucagonoma in this case. Glucagonomas are more commonly malignant than insulinomas. (Right) Axial CECT demonstrates a cystic lesion in the pancreatic uncinate process. The subtle nodular hypervascular rim around the lesion strongly suggests that this is a cystic NET.

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Pancreatic Neuroendocrine Tumors

Abbreviations • Pancreatic neuroendocrine tumor (NET)

Synonyms • Islet cell tumor

Definitions • Tumors arising from pancreatic endocrine cells (islets of Langerhans)

• •

Associated Syndromes • Multiple endocrine neoplasia type 1 (MEN1, gastrinomas), von Hippel-Lindau syndrome, neurofibromatosis type I, tuberous sclerosis

• •

IMAGING General Features • Best diagnostic clue ○ Well-circumscribed hypervascular pancreatic mass with hypervascular liver metastases • Location ○ 85% arise in pancreas, while 15% are ectopic – Most common ectopic locations: Duodenum, stomach, lymph nodes, and ovary ○ 90% of gastrinomas arise in gastrinoma triangle – Gastrinoma triangle defined by cystic duct and common bile duct (CBD) superiorly, 2nd and 3rd parts of duodenum inferiorly, and pancreatic neck and body medially – Most commonly arise in duodenal wall • Size ○ Varies from few mm to 10 cm • General concepts ○ More rare than tumors of exocrine pancreas ○ Divided into benign (well-differentiated endocrine tumor) or malignant (well/poorly differentiated neuroendocrine carcinoma) based on WHO classification ○ No longer divided into functioning or nonfunctioning, as all NET are now considered hormonally active ○ Now divided into syndromic (produce clinical syndrome with abnormal lab findings) or nonsyndromic – Syndromic tumors: Secrete multiple pancreatic hormones, but patients have single clinical syndrome □ Insulinoma, glucagonoma, gastrinoma, somatostatinoma, VIPoma (vasoactive intestinal polypeptide), carcinoid – Nonsyndromic tumors □ Hypofunctioning or clinically silent large tumors □ Larger than syndromic tumors at diagnosis due to lack of symptoms or laboratory abnormalities □ Cystic NETs more likely to be non-insulin-producing and nonsyndromic

CT Findings • Well-circumscribed pancreatic mass with noninfiltrative margins that is usually (but not always) hypervascular and most conspicuous on arterial phase ○ Lesions usually hyperenhance to lesser degree on venous phase, making smaller lesions difficult to detect – Rarely can be most conspicuous on venous phase

•

•

○ Syndromic tumors tend to be smaller at presentation (usually < 3 cm with insulinomas < 2 cm) ○ Nonsyndromic tumors much larger at presentation (average > 5 cm) – Usually hypervascular, but less so than syndromic – Large tumors are more likely to demonstrate central necrosis, cystic change, and calcification Lesions often demonstrate calcification (central or diffuse) Usually no biliary or pancreatic duct obstruction (unless large) or upstream pancreatic atrophy ○ Some small tumors may rarely secrete serotonin that can cause fibrosis and obstruction of pancreatic duct Invasion (rather than encasement) by tumor of mesenteric veins (portal vein or superior mesenteric vein) Cystic NET can mimic other pancreatic cystic lesions ○ Presence of peripheral enhancement or nodularity on arterial phase should strongly suggest diagnosis Metastases demonstrate similar characteristics to primary tumor: Hypervascular lymph node and liver metastases ○ Most common sites of metastases include liver, local lymph nodes, and bone (sclerotic lesions) ○ Fluid-fluid levels within neuroendocrine liver metastases described as specific feature Zollinger-Ellison syndrome (gastrinoma): Avid enhancement and wall thickening of proximal stomach

Pancreas

TERMINOLOGY

MR Findings • NETs tend to be hypointense (relative to normal pancreas) on T1WI, hyperintense on T2WI, and enhance similarly to CECT on T1WI C+ images ○ Homogeneous enhancement for small tumors < 2 cm ○ Heterogeneous enhancement with areas of necrosis for larger lesions • Liver metastases can often be very hyperintense on T2WI and mimic hemangiomas or cysts ○ Fluid-fluid levels may be visualized within liver metastases, particularly on T2WI ○ Liver metastases usually T1WI hypointense but may show hyperintensity due to intratumoral hemorrhage • DWI: Lesions show variable ADC values, but DWI can help identify tiny lesions that are otherwise occult

Ultrasonographic Findings • Endoscopic US: Sensitivity and specificity > 90% ○ Can be helpful to identify small NET that may be missed on CT/MR in patients with high clinical suspicion ○ Can "tattoo" lesion to guide laparoscopic surgery ○ No specific imaging features, as lesions tend to be hypoechoic or isoechoic to surrounding pancreas • Intraoperative US: Can detect small nonpalpable lesions and help guide surgical resection

Angiographic Findings • Hepatic venous sampling after arterial stimulation ○ Functioning tumors (esp. gastrinoma/insulinomas): Elevated levels of hormones suggests occult tumor

Nuclear Medicine Findings • PET/CT ○ Greater FDG uptake with more aggressive tumors ○ Novel tracers: GA-68-DOTA-peptide-based PET radiotracers (somatostatin analogue) and F18-DOPA 1055

Pancreas

Pancreatic Neuroendocrine Tumors

– Glucagonoma: Skin rash (necrolytic erythema migrans), diarrhea, diabetes, weight loss, and thromboembolism (DVT, PE) – VIPoma: Watery diarrhea, hypokalemia, achlorydia ○ Nonsyndromic tumors: May be asymptomatic or cause symptoms due to local mass effect/metastases

• Indium-111-DTPA-octreotide (OctreoScan) ○ Overall sensitivity of 75-100%; 50-60% for insulinomas

Imaging Recommendations • Multiphase CECT/MR: Arterial phase imaging is critical

DIFFERENTIAL DIAGNOSIS Intrapancreatic Splenule • Tail of pancreas is 2nd most common location for splenule • Identical enhancement to spleen on all contrast phases

Pancreatic Ductal Carcinoma • Hypovascular, infiltrative tumor associated with pancreatic/biliary ductal obstruction and pancreatic atrophy • Almost never demonstrates calcification (unlike NET) • Encases/narrows mesenteric veins (no tumor thrombus)

Pancreatic Metastases • Hypervascular metastases to pancreas (most commonly renal cell carcinoma) indistinguishable from NET

Pancreatic Serous Cystadenoma • Classic "microcystic" or "sponge" appearance with lesion consisting of many small enhancing septations and cysts • Solid variant may be indistinguishable from NET and appear as solid hypervascular mass

Peripancreatic Gastrointestinal Stromal Tumor • Lesions arising from stomach or duodenum may mimic NET, particularly when avidly enhancing

PATHOLOGY General Features • Etiology ○ Arise from amine precursor uptake and decarboxylation (APUD) cells ○ Pathogenesis and presentation – Insulinoma: -cell tumor hyperinsulinemia hypoglycemia – Gastrinoma: Islet cell tumor increased gastrin increased gastric acid peptic ulcer – Glucagonoma: -cell tumor increased glucagon classic skin rash and diabetes mellitus – Nonfunctioning: Derived from and cells • Genetics ○ MEN1 (hyperparathyroidism, pituitary adenoma, and pancreatic NETs) – Autosomal dominant pattern of inheritance – 80% develop NETs (often multiple)

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Syndromic tumors – Insulinoma: Symptoms of hypoglycemia, low glucose (< 50 mg/dL), and relief by IV glucose (Whipple triad) □ Palpitations, sweating, tremors, headache, coma – Gastrinoma (Zollinger-Ellison syndrome): Severe peptic ulcer disease, increased acidity, and diarrhea

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Demographics • Age ○ Insulinoma: 4th-6th decades ○ Gastrinoma: 4th-5th decades ○ NET can present at young age (< 30 years) in MEN1 • Gender ○ Insulinoma: M < F; gastrinoma: M > F • Epidemiology ○ Overall incidence of only 2.2 per 1 million, but incidence in autopsy studies may be as high as 10% – Small, benign NETs increasingly being identified incidentally on imaging ○ Insulinoma: Most common NET (50% of cases) – Usually solitary and benign (90%); 10% malignant ○ Gastrinoma: 2nd most common (~ 25% of cases) – Often multiple and malignant (60%) – 20-60% associated with MEN1 ○ Nonsyndromic: 3rd most common (~ 20% of cases) – Strong tendency to be malignant (80-100%) – Strong correlation between size of nonsyndromic tumors and malignancy, particularly when > 2 cm

Natural History & Prognosis • Prognosis ○ Far better prognosis compared to pancreatic adenocarcinoma ○ Excellent prognosis for insulinomas, which are usually benign, but poor prognosis for gastrinomas ○ Nonsyndromic tumors: 5-year survival of only 44% ○ Patients can live with metastases for many years

Treatment • Somatostatin analogs (e.g., Octreotide) for symptom relief for syndromic tumors (except somatostatinoma) • Syndromic NET or benign nonsyndromic NET without metastases surgically resected • Locally advanced NET without metastases should be resected if possible, even if negative margins not possible ○ May reduce complications and improve survival • NET with liver metastases: Resection of primary tumor may still have survival benefit ○ Some patients may be candidates for surgical resection or debulking of liver metastases ○ Liver metastases treated with chemoembolization or chemotherapy if patient not a surgical candidate • Neuroendocrine carcinomas treated with chemotherapy • Liver transplantation possible in patients with liver failure and metastases limited to liver

SELECTED REFERENCES 1.

Kawamoto S et al: Pancreatic neuroendocrine tumor with cystlike changes: evaluation with MDCT. AJR Am J Roentgenol. 200(3):W283-90, 2013

Pancreatic Neuroendocrine Tumors Pancreas

(Left) Arterial phase CECT demonstrates an avidly enhancing pancreatic neck mass in keeping with a pancreatic NET. In this case, the upstream pancreas is markedly atrophic , an atypical feature for NETs, which do not typically obstruct the pancreatic duct or cause parenchymal atrophy. (Right) While the mass is still enhancing on this axial venous phase CECT image from the same patient, note that the mass demonstrates a much lesser degree of enhancement compared to the arterial phase image.

(Left) Axial CECT demonstrates a cystic lesion in the pancreatic tail. While an IPMN or MCN are possibilities, the peripheral enhancement and enhancing soft tissue should suggest the correct diagnosis of cystic NET. (Right) Coronal CECT shows a hypovascular mass in the pancreatic uncinate, with multiple liver metastases . Note that the lesion is invading the SMV , a feature uncommon with adenocarcinoma and more common with NET. This was found to be a NET at resection.

(Left) Axial CECT in the arterial phase demonstrates a massive hypervascular NET replacing nearly the entirety of the pancreas. Nonsyndromic tumors, as in this case, are often larger at presentation. (Right) Axial T2WI MR in the same patient demonstrates several hyperintense liver lesions . While these lesions could easily be mistaken for cysts or hemangiomas, neuroendocrine metastases to the liver are well known for being very T2 hyperintense.

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Pancreas

Pancreatic Neuroendocrine Tumors

(Left) Coronal CECT shows marked fold thickening and wall hyperenhancement in the proximal aspect of the stomach. The more distal stomach demonstrates normal wall thickness . This appearance is typical of Zollinger-Ellison syndrome. (Right) Axial venous phase CECT from the same patient shows marked fold thickening in the proximal stomach , with a subtle enhancing mass in the pancreatic body representing a gastrinoma. In this case, the mass was not visible on the arterial phase, unusual for NETs.

(Left) Axial CECT shows a hypodense mass with central calcifications in the pancreatic body. Note the atrophy of the distal pancreas, an unusual feature for NETs. ~15% of NETs calcify, while pancreatic adenocarcinomas almost never calcify. (Right) Axial CECT demonstrates a NET invading and distending the splenic vein . NETs, unlike pancreatic adenocarcinomas, do not narrow/occlude the mesenteric veins, but may invade the veins with hypervascular tumor thrombus.

(Left) Axial CECT in a patient suspected to have an insulinoma based on clinical symptoms shows a small, hypervascular mass in the head of the pancreas. (Right) Intraoperative ultrasound in the same patient demonstrates a hypervascular hypoechoic lesion that was not palpable. The patient underwent a Whipple resection, and an insulinoma was found at pathology. Intraoperative ultrasound is extremely valuable to localize lesions and to guide surgical resection of small NETs.

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Pancreatic Neuroendocrine Tumors Pancreas

(Left) Axial CECT in a patient with a NET demonstrates multiple liver metastases with fluid-fluid levels. Although uncommon, this feature has been described as specific for neuroendocrine tumor liver metastases. (Right) Axial CECT demonstrates a hypervascular mass in the pancreatic tail, compatible with a neuroendocrine tumor. Note that the large metastatic lesion in the liver demonstrates relatively similar enhancement to the primary pancreatic tumor.

(Left) Axial CECT shows a pancreatic NET invading the portal vein with a large liver metastasis . Treatment with chemoembolization led to several years of effective palliation. Malignant NETs often invade the portal vein with widespread hepatic metastases. (Right) Axial arterial phase CECT demonstrates multiple markedly hypervascular liver metastases from a primary pancreatic NET . As in this case, NET and their metastases are often markedly hypervascular in the arterial phase.

(Left) Axial volume-rendered CECT image in a patient with a suspected insulinoma shows a hypervascular mass in the head of the pancreas. (Right) Axial CECT of the liver in the same patient shows areas of low-attenuation steatosis adjacent to small hypervascular liver metastases . This focal perilesional steatosis, likely due to the localized effects of insulin from the functioning metastases, is a rare but recognized manifestation of metastatic insulinomas.

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Pancreas

Pancreatic Solid and Pseudopapillary Neoplasm KEY FACTS

IMAGING • Well-defined, heterogeneous, large mass with a thick, enhancing capsule ○ Most often solid, but can have variable internal cystic components and intratumoral hemorrhage • Capsule enhances on CECT and T1 C+ MR and appears as rim of low T2 signal intensity • Frequent peripheral or central calcification (45-50%) • Presence of internal hemorrhage highly characteristic feature, and may result in fluid-fluid or hematocrit levels ○ Internal hemorrhage usually easier to perceive on MR • Usually no biliary or pancreatic ductal obstruction • Metastatic disease is very uncommon, but most often metastasizes to liver and locoregional lymph nodes

PATHOLOGY • Rare: < 3% of all pancreatic tumors

(Left) Graphic shows a large encapsulated mass arising from the pancreatic tail with prominent solid and cystic or hemorrhagic components. (Right) Axial CT in 42-year-old man with an incidentally discovered pancreatic mass demonstrates a wellcircumscribed, predominantly cystic mass in the pancreatic body with a clearly visible enhancing capsule. The mass was found to be a solid pseudopapillary neoplasm (SPEN) at surgery.

(Left) Axial CT in a 21-year-old woman shows a complex cystic-solid mass with peripheral rim calcification in the tail of the pancreas. Endoscopic ultrasound (not shown) confirmed a complex cystic mass. Needle aspiration of the mass at ultrasound yielded fluid that had few cells and no elevated tumor markers. The fluid was not mucoid. (Right) The resected mass shows areas of hemorrhage and necrosis, surrounded by tissues with solid and pseudopapillary projections , compatible with a SPEN.

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• Previously thought to have separate benign and malignant subtypes, but recent WHO classification defines all SPEN as low-grade malignancies ○ Low malignant potential (< 10% metastasize or recur)

CLINICAL ISSUES • > 90% occur in women • Almost always arises in patients < 35 years (rarely reported in older adults) ○ Accounts for 8-16% of pancreatic tumors in children • Possible predilection for African Americans and Asians • Most patients are symptomatic, with abdominal pain most common presenting symptom • Treatment: Complete surgical resection

DIAGNOSTIC CHECKLIST • Consider SPEN when confronted by an encapsulated solid pancreatic mass in a young woman, particularly when there is evidence of internal hemorrhage

Pancreatic Solid and Pseudopapillary Neoplasm

Abbreviations • Solid and pseudopapillary neoplasm (SPEN)

Synonyms • Hamoudi tumor, Franz tumor

IMAGING

Pancreatic Serous Cystadenoma • Classically demonstrates microcystic or "sponge" appearance with multiple small internal cystic components • Typically no biliary/pancreatic ductal obstruction • Usually seen in older women ("grandmother tumor")

PATHOLOGY General Features

General Features

• Rare: < 3% of all pancreatic tumors

• Best diagnostic clue ○ Encapsulated solid mass with cystic components and internal hemorrhage in a young woman • Location ○ Can occur anywhere in pancreas without predisposition for any location • Size ○ Average: 5 cm, range: 2.5-20 cm

Staging, Grading, & Classification

CT Findings • Well-defined, heterogeneous, encapsulated mass with thick, enhancing capsule ○ Usually quite large at presentation (mean > 5 cm) • Frequent peripheral or central calcification (45-50%) • Most often solid, but can have variable cystic components and intratumoral hemorrhage ○ Usually very little enhancement, with "solid" components often representing intratumoral blood products • Metastatic disease is very uncommon, but most often metastasizes to liver and locoregional lymph nodes • Usually no biliary or pancreatic ductal obstruction • Gross vascular invasion or occlusion on imaging is rare

MR Findings • Large, well-demarcated mass with central areas of low and high T1 signal intensity (hemorrhage) ○ Presence of internal hemorrhage highly characteristic feature, and may result in fluid-fluid or hematocrit levels • Solid or cystic with minimal enhancement on T1WI C+ • Capsule appears as rim of low T2 signal intensity and enhances on post-gadolinium images

Nuclear Medicine Findings • PET/CT ○ Variable, but can demonstrate increased FDG uptake

Imaging Recommendations • Protocol advice ○ CECT or MR

DIFFERENTIAL DIAGNOSIS Mucinous Cystic Pancreatic Tumor • Most common in middle-aged to elderly women • Cystic lesion in body or tail of pancreas consisting of a few (< 6) sizeable (> 2 cm) cystic locules (± thick wall)

Pancreatic Ductal Carcinoma • Hypodense, poorly marginated, unencapsulated mass resulting in pancreatic ductal dilatation and atrophy • Strong tendency to obstruct pancreatic &/or bile ducts • Most often occurs in older adults

Pancreas

TERMINOLOGY

• Previously thought to have benign and malignant subtypes • Most recent WHO classification defines all SPEN as lowgrade malignancies

Gross Pathologic & Surgical Features • Thick, fibrous, hypervascular capsule surrounding mixture of solid and cystic areas with hemorrhage and necrosis

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Most patients are symptomatic, with abdominal pain most common presenting symptom ○ Nausea, vomiting, weight loss, jaundice ○ Palpable abdominal mass (especially in children) • Lab data: Usually normal, with tumor markers (such as CA 19-9) not typically elevated

Demographics • Age ○ < 35 years (rarely reported in older adults) ○ 8-16% of pancreatic tumors in children • Gender ○ > 90% are women • Ethnicity ○ Possible predisposition for African Americans and Asians

Natural History & Prognosis • Complications: Hemorrhage, biliary obstruction • Prognosis: Excellent after surgical resection ○ < 10% metastasize or recur and < 2% mortality ○ Distant metastases in 8% and nodal metastases in ~ 2%

Treatment • Complete surgical resection is curative in most patients • No consensus on need for adjuvant chemotherapy

DIAGNOSTIC CHECKLIST Consider • Consider SPEN when confronted by an encapsulated solid pancreatic mass in a young woman

SELECTED REFERENCES 1.

Raman SP et al: Institutional experience with solid pseudopapillary neoplasms: focus on computed tomography, magnetic resonance imaging, conventional ultrasound, endoscopic ultrasound, and predictors of aggressive histology. J Comput Assist Tomogr. 37(5):824-33, 2013

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Pancreas

Pancreatic Solid and Pseudopapillary Neoplasm

(Left) Axial NECT shows a solid and cystic mass within the body and tail of the pancreas. Note the dense rim calcifications within a portion of the mass. (Right) Endoscopic ultrasound in the same patient clearly delineates the solid and cystic components of the lesion, a surgically proven SPEN.

(Left) Coronal CECT in a 37year-old man shows a hemorrhagic SPEN in the left upper quadrant with blood tracking downwards in the retroperitoneum. SPENs are frequently associated with internal hemorrhage. (Right) Axial CECT in a 19-year-old woman with an incidentally found pancreatic lesion shows a solid pancreatic head mass with central dystrophic calcification that was found to be a SPEN at surgery.

(Left) Coronal volumerendered CECT in a 23-yearold woman shows 2 pancreatic masses , each of which is predominantly cystic with solid components and demonstrate calcification and peripheral capsules. Both masses were found to be SPENs. (Right) Axial CECT in a 21-year-old man with LUQ pain shows a predominantly solid pancreatic tail mass with a peripheral capsule. Note that the mass has both peripheral and central calcification . It was found to be a SPEN at surgery.

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Pancreatic Solid and Pseudopapillary Neoplasm Pancreas

(Left) Axial CECT in a 15-yearold girl presenting with a palpable LUQ mass demonstrates a large predominantly cystic mass with peripheral solid components . The mass is well circumscribed with an enhancing peripheral capsule . The lesion was found to be a SPEN. (Right) Axial CECT in a 29-year-old woman with an incidentally discovered SPEN demonstrates a predominantly cystic mass in the pancreatic body with an internal hematocrit level .

(Left) Axial T1 FS MR demonstrates a mass in the pancreatic head in a 12-yearold girl. Notice the T1 hyperintense hemorrhage within the mass, a feature which is quite common in SPENs. (Right) Axial CECT in a 30-year-old woman demonstrates a large SPEN arising from the pancreatic tail. The mass has a mixture of densities, including higher attenuation material that could represent solid tissue or blood products, as well as extensive calcification along the margin of the lesion.

(Left) Axial CECT in a 24-yearold woman demonstrates a predominantly cystic mass arising from the pancreas. Curvilinear calcifications are seen along the margin of the mass. This lesion was found to be a SPEN at resection. (Right) Coronal CECT in a 16-year-old girl demonstrates a homogeneous solid mass in the pancreatic head, found to be a SPEN at surgical resection. SPEN tumors should be a primary consideration when confronted with a solid pancreatic mass in a young female patient.

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Pancreas

Pancreatic Metastases and Lymphoma KEY FACTS

IMAGING • Pancreatic metastases ○ Can be solitary (73%), multiple (10%), or diffusely infiltrative (15%) ○ Enhancement pattern mimics primary tumor – Hypervascular: Most commonly renal cell cancer (RCC) – Hypovascular: Lung, breast, colon, melanoma ○ Concomitant intraabdominal metastases in > 60%, usually with widespread metastatic disease • Pancreatic lymphoma ○ Homogeneous soft tissue mass with little enhancement ○ Diffuse enlargement of pancreas with infiltrating tumor (± peripancreatic fat involvement) may mimic acute pancreatitis ○ Almost always associated lymphadenopathy or other sites of lymphomatous involvement ○ Tumor classically encases peripancreatic vessels without narrowing or occlusion

(Left) Axial CECT shows a hypodense mass in the pancreatic tail due to metastatic sarcoma. Metastases from lung, breast, colon, or melanoma could have a similar appearance. (Right) Coronal MIP reconstruction of an arterial phase CECT demonstrates an avidly enhancing pancreatic mass in a patient with a history of prior nephrectomy for renal cell carcinoma (RCC), a characteristic appearance for an RCC metastasis. Based on appearance alone, this mass is indistinguishable from a neuroendocrine tumor.

(Left) Axial T1WI C+ MR shows an enhancing RCC metastasis in the pancreatic head. The pancreatic duct is mildly dilated upstream. Note the posterior position of the pancreatic tail as a result of a prior left nephrectomy for RCC several years prior to this scan. (Right) Axial CECT shows diffuse infiltration of the pancreas and invasion of the spleen by non-Hodgkin lymphoma. Also note the associated peripancreatic lymphadenopathy .

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○ No dilatation of pancreatic duct or biliary tree

TOP DIFFERENTIAL DIAGNOSES • Pancreatic ductal carcinoma ○ Usually focal hypodense mass that obstructs main pancreatic duct resulting in upstream ductal dilatation ○ Encases and narrows peripancreatic vessels • Pancreatic islet cell tumors ○ Usually hypervascular lesions which are indistinguishable from RCC metastases without clinical history

CLINICAL ISSUES • Prognosis of metastases to pancreas poor, although isolated metastases to pancreas may be amenable to resection (especially RCC) ○ RCC metastases to pancreas may occur 5-10 years after primary tumor resection • Prognosis for primary pancreatic lymphoma is poor, with 30% cure rate after treatment

Pancreatic Metastases and Lymphoma

CT Findings • Pancreatic metastases ○ May be solitary (73%), multiple (10%), or diffusely infiltrative (15%) ○ Enhancement pattern is variable, but typically mimics primary tumor – Hypervascular: Most often renal cell cancer (RCC) – Hypovascular: Lung, breast, melanoma, colon ○ Concomitant intraabdominal metastases in 60-95%, usually with widespread metastatic disease – Liver, nodes, adrenal (each ~ 30%) ○ Dilatation of pancreatic duct or bile ducts less common than pancreatic adenocarcinoma (40%) ○ Encasement or narrowing of peripancreatic vasculature is unusual • Pancreatic lymphoma ○ Most often presents as discrete homogeneous soft tissue mass with little enhancement ○ May rarely present as diffuse enlargement of pancreas with infiltrating tumor ± peripancreatic fat involvement – Infiltrating tumor may mimic acute pancreatitis ○ Almost always associated with lymphadenopathy (especially peripancreatic) and other sites of lymphomatous involvement ○ Tumor classically encases peripancreatic vasculature without narrowing or occlusion ○ No dilatation of pancreatic duct or biliary tree ○ No upstream atrophy of pancreatic parenchyma

MR Findings • Pancreatic metastases ○ RCC metastases typically demonstrate avid hypervascular enhancement (homogeneous when small and heterogeneous when large) on T1WI C+ – Usually low signal on T1WI and intermediate to high signal on T2WI ○ Hypovascular metastases may demonstrate a rim of peripheral enhancement • Pancreatic lymphoma ○ Typically low signal on T1WI and low to intermediate signal on T2WI with little enhancement on T1WI C+

Imaging Recommendations • Best imaging tool ○ CECT ± PET/CT depending on primary tumor FDG avidity • Protocol advice ○ CECT: Inclusion of arterial phase critical if RCC metastasis is suspected

DIFFERENTIAL DIAGNOSIS Pancreatic Ductal Carcinoma • Usually a focal hypoenhancing mass with abrupt obstruction of pancreatic duct ± bile duct ○ Diffuse infiltration of pancreas by tumor can very rarely occur, but much less commonly than lymphoma • Commonly encases and narrows adjacent vessels (much more often than metastases or lymphoma) • Bulky lymphadenopathy relatively uncommon

Pancreatic Islet Cell Tumors • Hypervascular lesions which are indistinguishable from RCC metastases without clinical history

Pancreas

IMAGING

PATHOLOGY General Features • Etiology ○ Pancreatic metastases – Found incidentally at autopsy in 3-11% of oncology patients with widespread malignancy – Most common primary sites: Renal (70%), breast (7%), lung (6%), colon (6%), melanoma (3%) ○ Pancreatic lymphoma – Primary lymphoma is very rare (< 1% of primary pancreatic tumors), and most often found in immunocompromised or elderly patients □ Usually B-cell non-Hodgkin lymphoma (NHL) – Secondary lymphoma is much more common (30% of patients with widespread lymphoma)

CLINICAL ISSUES Presentation • Most often detected on CT or PET/CT performed for staging of known cancer • Symptoms may result from involvement of pancreas, including jaundice, acute pancreatitis, or abdominal pain

Natural History & Prognosis • Pancreatic metastases ○ Usually diagnosed at same time as primary tumor, but can present up to many years later ○ RCC metastases to pancreas: May occur 5-10 years later ○ RCC metastases are often isolated only to pancreas, and may be amenable to resection • Prognosis ○ Pancreatic metastases: Very poor in most cases (depends on type of primary tumor), although prognosis slightly better for RCC metastases isolated to pancreas ○ Pancreatic lymphoma: Prognosis for secondary lymphomatous involvement dependent on lymphoma type – Prognosis for primary pancreatic lymphoma is poor, with 30% cure rate after treatment

DIAGNOSTIC CHECKLIST Consider • Consider pancreatic metastasis with a pancreatic lesion in a patient with known primary malignancy • Consider RCC metastases to pancreas even years after resection of primary tumor • Consider lymphoma with an infiltrative hypoenhancing pancreas mass with bulky lymphadenopathy and no biliary/pancreatic ductal obstruction

SELECTED REFERENCES 1.

Tosoian JJ et al: Resection of isolated renal cell carcinoma metastases of the pancreas: outcomes from the Johns Hopkins Hospital. J Gastrointest Surg. 18(3):542-8, 2014

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Pancreas

Pancreatic Metastases and Lymphoma

(Left) Axial CECT shows bilateral necrotic adrenal metastases from metastatic melanoma. Note also the associated pancreatic tail metastasis . (Right) Axial CT demonstrates a hypodense mass with stippled calcification involving the pancreatic head and neck. The stippled calcifications are not typical for pancreatic ductal adenocarcinoma and are more typical of this patient's mucinous colon cancer, which has metastasized to the pancreas.

(Left) Axial CECT shows multiple solid, hypodense lesions in the pancreas and kidneys . This combination of findings is typical of renal and pancreatic involvement from non-Hodgkin lymphoma. A neck node biopsy confirmed the diagnosis. (Right) Axial T1WI C+ MR demonstrates a subtle hypervascular lesion in the pancreatic head. Note the absence of the right kidney, a finding that should suggest the correct diagnosis of a RCC metastasis.

(Left) Curved planar reformation from a CECT shows a normal pancreatic duct . Note that the entire pancreatic body is displaced anteriorly by a large, hypodense, periaortic mass that directly invades the body of the pancreas . (Right) Curved planar reformation of the celiac axis in the same patient demonstrates encasement by hypodense nodal tissue. Biopsy of an axillary node revealed nonHodgkin lymphoma.

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Pancreatic Metastases and Lymphoma Pancreas

(Left) Axial CECT demonstrates a markedly enlarged, hypodense, infiltrated pancreas with surrounding induration and stranding. Superficially, this appearance could initially be suggestive of pancreatitis. (Right) Axial CECT from the same patient demonstrates extensive lymphadenopathy in the surrounding mesentery. Given this lymphadenopathy, the appearance of the pancreas represents diffuse lymphomatous infiltration of the pancreas in a patient with B-cell lymphoma.

(Left) Axial CECT shows a bulky exophytic mass extending from the neck of the pancreas and exhibiting marked mass effect on the stomach . The mass was found to be non-Hodgkin lymphoma after surgery. (Right) Axial CECT shows a small hypodense mass in the pancreatic body resulting in severe upstream pancreatic ductal dilatation and parenchymal atrophy. While the imaging features are strongly suggestive of pancreatic cancer, this turned out to be a colon cancer metastasis.

(Left) Axial CECT shows absence of the kidney in the left renal fossa and bulky hypervascular metastases to the pancreas and liver . While a neuroendocrine tumor could appear identical, the nephrectomy suggests the diagnosis of RCC metastases to the pancreas. (Right) Axial arterial phase CECT shows avidly enhancing masses in the pancreas and omentum . The left kidney is absent in this patient with RCC mets, which are typically highly vascular, making the inclusion of arterial phase imaging very helpful for detection.

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Pancreas

Atypical and Rare Pancreatic Tumors KEY FACTS

IMAGING • Anaplastic carcinoma ○ Extremely aggressive and almost always unresectable ○ Large, heterogeneous, moderately enhancing, exophytic mass with necrosis and cystic change • Small cell carcinoma ○ Highly aggressive, with hematologic and lymphatic metastases at time of diagnosis ○ Large, homogeneous, mildly enhancing mass with confluent local and distant lymphadenopathy ○ May be indistinguishable from lymphoma • Giant cell carcinoma (pleomorphic or osteoclast) ○ Resection often impossible due to large size ○ Large, heterogeneous, cystic, low-density mass with frequent hemorrhage, septation, and calcification • Acinar cell carcinoma ○ Slightly better prognosis than adenocarcinoma

(Left) Axial CECT demonstrates a wellcircumscribed, encapsulated, enhancing mass in the pancreatic head with solid and cystic components. This was found to be an acinar cell carcinoma at surgery. As in this case, these tumors often mimic the appearance of neuroendocrine tumors, albeit with less hyperenhancement. (Right) Axial CECT demonstrates a lobulated, well-circumscribed enhancing mass arising from the pancreatic tail. This mass was found to be an acinar cell carcinoma at surgery.

(Left) Axial CECT in a patient with known myeloma demonstrates a wellcircumscribed, enhancing mass in the pancreatic head. (Right) Axial CECT in the same patient shows that the mass causes no pancreatic ductal obstruction or parenchymal atrophy, highly atypical for an adenocarcinoma. The mass was found to be a rare pancreatic plasmacytoma at biopsy.

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○ Large, well-circumscribed mass with cystic degeneration, exophytic component, and enhancing capsule ○ Usually no biliary/pancreatic duct dilatation • Pancreatoblastoma ○ Poor prognosis: Worse outcomes in adults than children ○ Large, heterogeneous mass with frequent internal calcifications and necrosis/hemorrhage • Pancreatic plasmacytoma ○ Consider in patients with known myeloma ○ Homogeneous mass without pancreatic/biliary ductal obstruction or pancreatic atrophy • Pancreatic schwannoma ○ Usually benign, with malignant transformation very rare ○ Well-circumscribed mass ± cystic degeneration

TOP DIFFERENTIAL DIAGNOSES • Pancreatic adenocarcinoma, pancreatic neuroendocrine tumor, lymphoma, mucinous cystic neoplasm

Atypical and Rare Pancreatic Tumors

General Features • Anaplastic carcinoma ○ Large, heterogeneous, moderately enhancing, exophytic mass with necrosis and cystic change ○ Locally invasive with frequent lung and liver metastases • Small cell carcinoma ○ Large, homogeneous, mildly enhancing mass with confluent local and distant lymphadenopathy ○ May be indistinguishable from lymphoma • Giant cell carcinoma (pleomorphic or osteoclast) ○ Large, heterogeneous, cystic, low-density mass with frequent hemorrhage, septation, and calcification – Tendency to arise in pancreatic body and tail – Often grow to very large sizes (mean > 6 cm) ○ Local invasion and distant mets (liver, lung) uncommon • Acinar cell carcinoma ○ Large, well-circumscribed mass with cystic and necrotic degeneration and frequent exophytic component – Usually a well-defined enhancing capsule – Hypodense on both arterial and venous phases – Usually no biliary/pancreatic duct dilatation (even with large tumors) – Vascular encasement or occlusion uncommon (20%), and may invade portal vein or SMV ○ Commonly misdiagnosed as neuroendocrine tumor ○ Metastasizes to liver and local lymph nodes • Pancreatoblastoma ○ Can resemble either pancreatic adenocarcinoma or neuroendocrine tumors ○ Associated with Beckwith-Wiedemann and familial adenomatous polyposis ○ Large, heterogeneous mass with frequent internal calcifications and necrosis/hemorrhage – May be either well circumscribed or infiltrative ○ No pancreatic or biliary duct obstruction ○ Most common site of metastasis is liver • Pancreatic plasmacytoma ○ Homogeneous mass without pancreatic/biliary ductal obstruction or pancreatic atrophy ○ Mimics lymphoma, but usually no lymphadenopathy ○ Consider in patients with known myeloma • Pancreatic lipoma ○ Benign fat-containing mass (-80 to -120 HU) with a surrounding capsule – Most often occur in pancreatic head • Pancreatic schwannoma ○ Well-circumscribed, mildly hyperenhancing mass ± cystic/necrotic degeneration ○ Can closely mimic neuroendocrine tumors (usually with less avid vascularity)

Mucinous Cystic Neoplasm • Encapsulated cystic mass (± mural nodularity or soft tissue component) in pancreatic tail of middle-aged woman

Non-Hodgkin Lymphoma Involving Pancreas • Hypodense, homogeneous mass without pancreatic atrophy, ductal dilatation, or vascular narrowing/occlusion • Usually associated with widespread lymphadenopathy

CLINICAL ISSUES Presentation • Most common signs/symptoms ○ Weight loss, abdominal pain, palpable mass, jaundice • Other signs/symptoms ○ Small cell carcinoma: Paraneoplastic syndromes (ectopic ACTH, hypercalcemia, Cushing syndrome) ○ Acinar cell carcinoma: Lipase hypersecretion syndrome – Fevers, arthralgias, skin rash, and fat necrosis due to elevated lipase levels (often > 1000 U/L)

Demographics • Age ○ Mostly occur in older (> 60 years) men ○ Pancreatoblastoma most often occurs in children (mean age 2.5 years), but very rarely affects adults (mean age 40 years)

Natural History & Prognosis • Anaplastic carcinoma ○ Extremely aggressive with rapid local and distant spread and almost always unresectable at diagnosis ○ Mean survival of 2-3 months; 3-year survival rate = 3% • Small cell carcinoma ○ Highly aggressive, with hematologic (usually liver and lungs) and lymphatic metastases at time of diagnosis ○ Without treatment survival is less than a few months ○ May respond to chemotherapy ± radiotherapy • Acinar cell carcinoma ○ Slightly better prognosis than adenocarcinoma ○ Metastatic disease at presentation in ~ 50% • Giant cell carcinoma ○ Resection often (> 50%) impossible due to lesion size ○ Median survival of 11 months • Pancreatic plasmacytoma ○ Very sensitive to both radiation and chemotherapy • Pancreatoblastoma ○ Poor prognosis, with likely worse outcomes in adults compared to children • Pancreatic schwannoma ○ Usually benign, with malignant transformation very rare

SELECTED REFERENCES 1.

DIFFERENTIAL DIAGNOSIS

2.

Pancreatic Neuroendocrine Tumors • Hypervascular mass with frequent liver metastases

Pancreatic Ductal Carcinoma

Pancreas

IMAGING

3.

Sano M et al: Clinicopathological characteristics of anaplastic carcinoma of the pancreas with rhabdoid features. Virchows Arch. ePub, 2014 Temesgen WM et al: Osteoclastic giant cell tumor of the pancreas. Int J Surg Case Rep. 5(4):175-9, 2014 Raman SP et al: Acinar cell carcinoma of the pancreas: computed tomography features-a study of 15 patients. Abdom Imaging. Epub ahead of print, 2012

• Ill-defined, hypoenhancing mass obstructing pancreatic duct with upstream pancreatic atrophy 1069

Pancreas

Atypical and Rare Pancreatic Tumors

(Left) Axial CECT demonstrates a very well circumscribed, encapsulated low-density mass with internal cystic foci that was found to be a benign pancreatic schwannoma at resection. (Right) Axial CECT in a 56-year-old man shows an infiltrating hypodense mass in the pancreatic body and tail. While the appearance suggests adenocarcinoma, this is a rare pancreatoblastoma in an adult patient, a tumor much more common in children.

(Left) Coronal volumerendered CECT demonstrates a benign lipoma within the pancreatic head. The mass is quite simple in appearance, with only a few linear strands interspersed in the midst of fat density. (Right) Axial CECT in a patient with small cell carcinoma shows a hypodense mass in the neck of the pancreas. Note that the mass is homogeneously enhancing and conforms to the contours of adjacent structures. There is no biliary obstruction. However, multiple liver metastases are noted.

(Left) Axial CECT in a patient with anaplastic carcinoma shows a bulky mass involving the body of the pancreas with central necrosis . Note the obstruction of the common duct , which contains a metallic stent. (Right) Axial CECT in a patient with anaplastic carcinoma shows a large mass arising from the pancreatic tail with moderate vascularity and central necrosis . Note the invasion of the left kidney by the mass.

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Atypical and Rare Pancreatic Tumors Pancreas

(Left) Axial CECT in a patient with giant cell carcinoma shows a multiseptate, complex cystic mass arising from the tail of the pancreas. Note the focal calcification in one of the septations . (Right) Transverse intraoperative ultrasound shows a mass in the body of the pancreas that contains both solid and cystic elements. At pathology, this lesion was proven to be a rare giant cell carcinoma.

(Left) Axial CECT demonstrates a large, aggressive, hyperenhancing mass arising from the pancreatic tail and invading the spleen. The appearance would be more typical for an aggressive neuroendocrine tumor, but the mass was found at biopsy to be an acinar cell carcinoma. (Right) Coronal volume-rendered CECT shows an extremely well circumscribed, encapsulated, homogeneously hypodense mass arising exophytically from the pancreatic head, found to represent a rare acinar cell carcinoma.

(Left) Axial CECT in a patient with neurofibromatosis type I demonstrates a soft tissue density mass that follows the course of the splenic vein along the dorsal surface of the pancreas. There is no evidence of local invasion, metastases, or ductal obstruction. This was found to be a plexiform neurofibroma. (Right) Curved planar reformation from a CECT shows a small, welldefined hypodense mass in the head of the pancreas. The mass does not obstruct the pancreatic duct and was found to be benign peripancreatic schwannoma.

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INDEX

A

Abdomen, postoperative state, 124–125 Abdominal abscess, 72–75 - differential diagnosis, 73–74 - gastric diverticulum vs., 243 - genetics, 74 - image gallery, 72, 75 Abdominal aortic aneurysm, aortoenteric fistula associated with, 329 Abdominal calcifications, differential diagnosis, 67 Abdominal cavity, embryology and anatomy, 66 Abdominal fluid collection, congenital gallbladder abnormalities vs., 868 Abdominal foreign bodies. See Foreign bodies, abdominal. Abdominal hematoma, abdominal abscess vs., 74 Abdominal incision and injection sites, 126–129 Abdominal manifestations of systemic conditions, 4–63 - amyloidosis. See Amyloidosis. - barotrauma, 48–49 differential diagnosis, 49 pneumatosis of intestine vs., 395 - cystic fibrosis. See Cystic fibrosis. - foreign bodies, 42–47 - HIV/AIDS, 8–11 - imaging approach, 4–7 common hepatic artery, coronal volume rendered, 4 image gallery, 6–7 imaging modalities, 4 inferior vena cava, anatomy, 5 major lymphatics and lymph nodes, anatomy, 5 organizational approach, 4 - Kaposi sarcoma. See Kaposi sarcoma. - leukemia. See Leukemia. - lymphoma. See Lymphoma. - metastatic melanoma, 58–61 - mononucleosis, 16–17 - post-transplant lymphoproliferative disorder, 50–53 complication of small intestine transplantation, 432 differential diagnosis, 52 - sarcoidosis. See Sarcoidosis. - sickle cell anemia. See Sickle cell anemia. - superior vena cava obstruction, 36–37 differential diagnosis, 37 portal hypertension and varices vs., 116 - systemic hypotension, 34–35 differential diagnosis, 35 ischemic enteritis associated with, 413 - tuberculosis. See Tuberculosis. - vasculitis. See Vasculitis.

Abdominal mesothelioma, 140–143 - associated abnormalities, 142 - differential diagnosis, 141–142 - histologic types, 142 - image gallery, 140, 143 - peritoneal metastases vs., 146 - pseudomyxoma peritonei vs., 150 Abdominal neoplasms, benign - desmoid. See Desmoid tumors. - intestinal lymphangiectasia associated with, 385 - lymphangioma (mesenteric cyst). See Lymphangioma (mesenteric cyst). Abdominal neoplasms, malignant - abdominal mesothelioma. See Abdominal mesothelioma. - intestinal lymphangiectasia associated with, 385 - peritoneal metastases. See Peritoneal metastases. - pseudomyxoma peritonei. See Pseudomyxoma peritonei. Abdominal surgery - desmoid neoplasms associated with, 38 - ileus associated with, 387 - omental infarct associated with, 90 - paraduodenal hernia associated with, 106 - sclerosing mesenteritis associated with, 82 - transmesenteric postoperative hernia associated with, 109 Abdominal trauma, sclerosing mesenteritis associated with, 82 Abdominal wall - eventration and paralysis of diaphragm, 152 - hernias. See Hernias, external; Hernias, internal. - imaging approach, 66–71 differential diagnosis, 67–68 embryology and relevant anatomy, 66–67 image gallery, 71 - neoplasms, abdominal incision and injection sites vs., 128 - postoperative state, 124–125 - traumatic diaphragmatic rupture, 120–123 - varices, imaging, in portal hypertension, 115 Abdominal wall defect (hernia), differential diagnosis, 68 Abdominal wall mass, differential diagnosis, 68 Abruptio placentae, HELLP syndrome associated with, 734 Abscess - abdominal, 72–75 differential diagnosis, 73–74 gastric diverticulum vs., 243 - biloma vs., 939 - fungal microabscesses, splenic infection and abscess associated with, 556 - hepatic. See Hepatic abscess. i

INDEX - hepatic amebic, 608–611 differential diagnosis, 609 hepatic pyogenic abscess vs., 601 - hepatic pyogenic. See Hepatic pyogenic abscess. Absent diaphragm sign, 121 Acalculous cholecystitis, 906–909 - acute calculous cholecystitis vs., 904 - differential diagnosis, 907–908 - image gallery, 906, 909 - risk factors, 908 Accessory spleen, 548–549 - differential diagnosis, 549 - intrapancreatic, pancreatic neuroendocrine tumors vs., 1056 - polysplenia vs., 552 - splenosis vs., 571 Acetic acid, caustic esophagitis associated with, 173 Achalasia. See Esophageal achalasia. Acids, caustic esophagitis associated with, 173 Acinar cell carcinoma, pancreatic, 1069. See also Atypical and rare pancreatic tumors. Acquired C1-INH deficiency, intestinal (angioneurotic) angioedema associated with, 381 Acute appendicitis - mucocele of appendix vs., 485 - omental infarct vs., 89 Acute calculous cholecystitis, 902–905 - acalculous cholecystitis vs., 907 - differential diagnosis, 904 - image gallery, 902, 905 - staging, grading, & classification, 904 Acute cholangitis. See Ascending cholangitis. Acute cholecystitis, Mirizzi syndrome associated with, 920 Acute edematous pancreatitis - autoimmune (IgG4) pancreatitis vs., 1009 - involving groove, groove pancreatitis vs., 1004 Acute fatty liver of pregnancy, HELLP syndrome vs., 733 Acute ileus - cecal volvulus vs., 507 - sigmoid volvulus vs., 503 Acute injury, pancreatic trauma vs., 1015 Acute mesenteric ischemia. See Ischemic enteritis. Acute myocardial infarction, ileus associated with, 387 Acute pancreatitis and complications, 990–999 - acute calculous cholecystitis vs., 904 - complications central necrosis (disconnected duct syndrome), 991 extrapancreatic fat necrosis, 991 fluid collections, 991 infected pancreatic necrosis, 991 pseudoaneurysm, 991 venous thrombosis, 991 - differential diagnosis, 992 - gastritis vs., 244 - genetics, 992 - image gallery, 990, 994–999 - staging, grading, & classification, 992–993 - subtypes interstitial edematous pancreatitis, 991 necrotizing pancreatitis, 991 - systemic hypotension vs., 35 ii

Acute pyogenic cholangitis, AIDS cholangiopathy vs., 891 Acute renal failure, HELLP syndrome associated with, 734 Acute right lower quadrant pain, differential diagnosis, 454 Acute viral hepatitis, passive hepatic congestion vs., 707 AD (autosomal dominant) polycystic liver disease, 594–597 - associated abnormalities, 595–596 - biliary hamartoma vs., 795 - Caroli disease vs., 871 - differential diagnosis, 595 - genetics, 595 - hepatic cyst vs., 765 - image gallery, 594, 597 - peribiliary cysts vs., 677 Adenitis, mesenteric. See Mesenteric adenitis and enteritis. Adenocarcinoma - ampullary, duodenal carcinoma vs., 335 - colonic metastatic, metastatic melanoma vs., 60 mucocele of appendix associated with, 485 - colonic metastases and lymphoma vs., 541 - duodenal. See Duodenal carcinoma. - esophageal carcinoma associated with, 230 - pancreatic. See Pancreatic ductal carcinoma. - pancreatic head asymmetric fatty lobulation of pancreas vs., 987 involving ampulla, ampullary carcinoma vs., 961 - periampullary, duodenal carcinoma vs., 335 - rectal carcinoma associated with, 532 Adenoma. See also Cystadenoma. - hepatic. See Hepatic adenoma. - mucinous macrocystic adenoma. See Mucinous cystic pancreatic tumor. - rectal villous adenoma, rectal carcinoma vs., 531 - small bowel carcinoma associated with, 443 - villous adenoma. See Villous adenoma, colon. Adenoma-carcinoma sequence - ampullary carcinoma associated with, 962 - duodenal carcinoma associated with, 335 - gallbladder carcinoma associated with, 958 - pancreatic intraductal papillary mucinous neoplasm (IPMN) associated with, 1050 - small bowel carcinoma associated with, 443 Adenomatous polyps. See also Familial adenomatous polyposis (FAP). - colon carcinoma associated with, 526 - colonic polyps associated with, 518 - duodenal, 331 - duodenal carcinoma associated with, 335 - gastric carcinoma associated with, 300 - hyperplastic cholecystoses vs., 924 - tubulovillous adenomatous polyps, colonic, 517 - villous, colonic, 517 Adenomyomatosis, gallbladder. See Gallbladder adenomyomatosis. Adenopathy, generalized: intestinal metastases and lymphoma associated with, 446 Adhesions, small bowel obstruction associated with, 390

INDEX Adrenal gland, CT findings - leukemia and lymphoma, 55 - metastatic melanoma, 59 - post-transplant lymphoproliferative disorder, 51 Adrenal lesions, tuberculosis vs., 14 Adrenal mass, gastric diverticulum vs., 243 Adrenal tuberculosis, radiologic findings, 13 Adynamic ileus. See Ileus, adynamic or paralytic. Aerophagia - ileus vs., 387 - small bowel obstruction vs., 390 Afferent loop syndrome, complication of partial gastrectomy, 272 Aflatoxins, hepatocellular carcinoma associated with, 808 Age, colonic diverticulosis associated with, 489 Agenesis of dorsal pancreas, 980 - differential diagnosis, 980 - malrotation of small intestine associated with, 349 - pancreas divisum vs., 984 Agenesis of gallbladder - congenital absence of hepatic segments associated with, 599 - congenital gallbladder abnormalities associated with, 868 Agenesis of hepatic lobes or segments. See Congenital absence of hepatic segments. Aggressive fibromatosis. See Desmoid tumors. AIDS cholangiopathy, 890–891 - acalculous cholecystitis vs., 908 - autoimmune (IgG4) cholangitis vs., 932 - differential diagnosis, 891 - primary sclerosing cholangitis vs., 936 - staging, grading, & classification, 891 AIDS/HIV. See HIV/AIDS. AIDS-related cholangitis, ascending cholangitis vs., 883 AIDS-related gastritis, 245 Alcohol use - acute pancreatitis and complications associated with, 992 - chronic pancreatitis associated with, 1002 - gastric ulcer associated with, 250 - groove pancreatitis associated with, 1004 - pancreatic ductal carcinoma associated with, 1036 Alcoholic hepatitis - autoimmune hepatitis vs., 631 - hepatic injury from toxins vs., 639 Alcoholic liver disease, 626–629 - cirrhosis associated with, 644 - differential diagnosis, 627 - image gallery, 626, 628–629 Alcoholism - chronic, intramural pseudodiverticulosis associated with, 207 - duodenal carcinoma associated with, 335 Alimentary tract, embryologic: intestinal carcinoid tumor associated with, 440 ALK gene, aberrant expression: hepatic inflammatory pseudotumor associated with, 804 Alkaline agents, caustic esophagitis associated with, 173

Allergic angioedema, intestinal (angioneurotic) angioedema associated with, 381 Amebiasis - intestinal parasites and infestation associated with, 359 - toxic megacolon associated with, 471 Amebic abscess, hepatic, 608–611 - differential diagnosis, 609 - hepatic pyogenic abscess vs., 601 Amebic colitis, hepatic amebic abscess associated with, 609 Amiodarone therapy, hemochromatosis vs., 681 Ampullary adenocarcinoma, duodenal carcinoma vs., 335 Ampullary adenoma, ampullary carcinoma vs., 961 Ampullary carcinoid tumor, ampullary carcinoma vs., 961 Ampullary carcinoma, 960–963 - differential diagnosis, 961 - duodenal polyps vs., 332 - genetics, 962 - image gallery, 960, 963 - staging, grading, & classification, 962 Ampullary stenosis, AIDS cholangiopathy vs., 891 Amyloidosis, 26–27 - Chagas disease of esophagus vs., 165 - dialysis-related, 27 - differential diagnosis, 27 - genetics, 27 - primary biliary cirrhosis vs., 653 - sarcoidosis vs., 29 Anabolic steroids - hepatic adenoma associated with, 787 - hepatic angiosarcoma associated with, 839 Anaplastic carcinoma, pancreatic, 1069. See also Atypical and rare pancreatic tumors. Anastomotic leak - complication of partial gastrectomy, 271 - post-esophagectomy, 219 Anastomotic strictures - biliary ductal, ischemic bile duct injury vs., 944 - complication of pancreatic surgery, 1019–1020 - complication of small intestine transplantation, 431 - post-esophagectomy, 219–220 Androgens, hepatocellular carcinoma associated with, 808 Aneurysm. See also Pseudoaneurysm. - aortic. See Aortic aneurysm. - splenic artery aneurysm or pseudoaneurysm, accessory spleen vs., 549 Aneurysmal dilation of small bowel lumen, differential diagnosis, 343 Angioedema, intestinal (angioneurotic), 380–381 - differential diagnosis, 381 - ischemic enteritis vs., 413 Angiomyolipoma and lipoma, hepatic, 798–801 - differential diagnosis, 799 - postoperative changes of liver vs., 746 Angiomyolipoma, splenic - CT findings, 575 - key concepts, 575 - MR findings, 576 - ultrasonographic findings, 576 Angiosarcoma, hepatic, 838–841 - associated abnormalities, 839 iii

INDEX - differential diagnosis, 839 - hepatic cavernous hemangioma vs., 774 - image gallery, 838, 840–841 - undifferentiated sarcoma vs., 843 Angiosarcoma, splenic - CT findings, 576 - key concepts, 575 - MR findings, 576 - ultrasonographic findings, 576 Ankylosing spondylitis - Crohn disease associated with, 372 - ulcerative colitis associated with, 468 Annular pancreas, 981 - differential diagnosis, 981 - duodenal carcinoma vs., 335 - malrotation of small intestine associated with, 349 - pancreas divisum vs., 984 Anticentromere antibodies, associated with HLA-DR1, 2, and 5: esophageal scleroderma associated with, 190 Antitopoisomerase 1 antibodies, associated with HLA-DR5 - esophageal scleroderma associated with, 190 - intestinal scleroderma associated with, 378 Antral gastritis, 245 Antrectomy, gastric bezoar associated with, 261 Aorta, small: CT findings in systemic hypotension, 35 Aortic aneurysm - abdominal, aortoenteric fistula associated with, 329 - aortoenteric fistula associated with, 329 - superior vena cava obstruction vs., 37 Aortic dissection, superior vena cava obstruction vs., 37 Aortoenteric fistula, 328–329 APC gene deletion, colon carcinoma associated with, 526 APC gene mutation - desmoid neoplasms associated with, 38 - duodenal polyps associated with, 332 - familial polyposis and Gardner syndrome associated with, 536 - gastric polyps associated with, 288 Appendagitis, epiploic, 498–501 - differential diagnosis, 499–500 - image gallery, 498, 501 - intussusception associated with, 400 - omental infarct vs., 89 Appendiceal carcinoids, 439 Appendiceal carcinoma, mesenteric adenitis and enteritis vs., 35 Appendiceal mucocele, 484–487 - appendiceal tumors vs., 540 - associated abnormalities, 485 - differential diagnosis, 485 - image gallery, 484, 486–487 Appendiceal tumors, 540 - appendicitis vs., 480 - differential diagnosis, 540 - mucin-producing tumor, pseudomyxoma peritonei associated with, 150 - mucocele of appendix vs., 485 Appendicitis, 478–483 - acute mucocele of appendix vs., 485 omental infarct vs., 89 iv

appendiceal tumors vs., 540 differential diagnosis, 480 epiploic appendagitis vs., 499 image gallery, 478, 481–483 Meckel diverticulum vs., 353 mesenteric adenitis and enteritis vs., 35 staging, grading, & classification, 480 transient hepatic attenuation or intensity difference associated with, 692 APUD cells, pancreatic neuroendocrine tumors associated with, 1056 Apudomas, intestinal carcinoid tumor associated with, 440 Arsenicals, hepatic angiosarcoma associated with, 839 Arterial thromboses, Crohn disease associated with, 372 Arterioportal shunt, 696–699 - associated abnormalities, 698 - classification, 698 - differential diagnosis, 697 - image gallery, 696, 699 Arteriosclerotic disease, ischemic colitis associated with, 476 Arteriovenous fistula, traumatic intrahepatic: hereditary hemorrhagic telangiectasia vs., 727 Arteriovenous malformations, pulmonary: hereditary hemorrhagic telangiectasia associated with, 728 Arteriovenous shunting - localized, focal nodular hyperplasia associated with, 782 - within tumors, hereditary hemorrhagic telangiectasia vs., 727 Arthritis, Crohn disease associated with, 372 Artifacts - biliary MRCP artifacts and pitfalls, 863–864 - gastric ulcer vs., 249–250 - splenic metastases and lymphoma vs., 580 - streaming, portal vein occlusion vs., 702 Asbestos-related pleural and parenchymal lung disease, abdominal mesothelioma associated with, 142 Ascariasis - intestinal parasites and infestation associated with, 359 - pancreatobiliary. See Pancreatobiliary parasites. Ascending cholangitis, 882–885 - associated abnormalities, 884 - autoimmune (IgG4) cholangitis vs., 932 - biliary IPMN vs., 968 - Caroli disease vs., 872 - differential diagnosis, 883 - hepatic pyogenic abscess associated with, 601 - image gallery, 882, 885 - ischemic bile duct injury vs., 944 - pancreatobiliary parasites vs., 887 - primary sclerosing cholangitis vs., 936 - recurrent pyogenic cholangitis vs., 879 - risk factors, 884 - staging, grading, & classification, 884 Ascites, 84–87 - benign, peritonitis vs., 77 - complication of small intestine transplantation, 432 - differential diagnosis, 86 - exudative general features, 85 -

INDEX vicarious excretion of contrast medium vs., 153 high-attenuation (hypodense), differential diagnosis, 68 image gallery, 84, 87 infectious, ascites vs., 86 loculated abdominal abscess vs., 74 lymphangioma (mesenteric cyst), 133 - malignant, ascites vs., 86 - Ménétrier disease associated with, 257 - other causes, portal hypertension and varices vs., 116 - transudative, 85 Asplenia, 550–553. See also Polysplenia. - associated syndromes, 550 - differential diagnosis, 552 - imaging, 551–552 - malrotation of small intestine associated with, 349 Asymmetric fatty infiltration of pancreatic head, pancreatic ductal carcinoma vs., 1036 Asymmetric fatty lobulation of pancreas, 986–987 Ataxia telangiectasia, pancreatic ductal carcinoma associated with, 1036 Atherosclerosis, aortoenteric fistula associated with, 329 Atrophic gastritis - chronic, gastric polyps associated with, 288 - gastric carcinoma associated with, 300 - imaging findings, 245 Atypical and rare pancreatic tumors, 1068–1071 Auerbach plexus, myenteric ganglia in, idiopathic abnormality of: esophageal achalasia associated with, 182 Autoimmune (IgG4) cholangitis, 930–933 - AIDS cholangiopathy vs., 891 - associated abnormalities, 932 - differential diagnosis, 931–932 - hepatic inflammatory pseudotumor vs., 803 - image gallery, 930, 933 - primary sclerosing cholangitis vs., 936 - staging, grading, & classification, 932 Autoimmune disorders - hepatic inflammatory pseudotumor associated with, 804 - intestinal scleroderma associated with, 378 - nodular regenerative hyperplasia associated with, 664 - pneumatosis of intestine vs., 395 - primary biliary cirrhosis associated with, 654 - sarcoidosis associated with, 30 - sclerosing mesenteritis associated with, 82 Autoimmune hepatitis, 630–631 - alcoholic liver disease vs., 627 - differential diagnosis, 631 - hepatic injury from toxins vs., 639 - primary biliary cirrhosis associated with, 654 - staging, grading, & classification, 631 - viral hepatitis vs., 621 Autoimmune (IgG4) pancreatitis, 1008–1011 - autoimmune (IgG4) cholangitis associated with, 932 - chronic pancreatitis associated with, 1002 - differential diagnosis, 1009 - focal, pancreatic ductal carcinoma vs., 1036 - image gallery, 1008, 1010–1011 - sclerosing mesenteritis associated with, 82 -

- staging, grading, & classification, 1009 Autosomal dominant polycystic kidney disease (ADPKD) - AD polycystic liver disease associated with, 595 - biliary hamartoma associated with, 795 - Caroli disease associated with, 872 - nonneoplastic pancreatic cysts associated with, 1032 Autosomal dominant polycystic liver disease, 594–597 - associated abnormalities, 595–596 - biliary hamartoma vs., 795 - Caroli disease vs., 871 - differential diagnosis, 595 - genetics, 595 - hepatic cyst vs., 765 - image gallery, 594, 597 - peribiliary cysts vs., 677 Autosomal dominant trait, hereditary hemorrhagic telangiectasia associated with, 728 Autosomal recessive disorders/inheritance - Caroli disease associated with, 872 - congenital hepatic fibrosis associated with, 592 - hemochromatosis associated with, 681 - sickle cell anemia associated with, 24 - Wilson disease associated with, 685 Autosomal recessive polycystic kidney disease (ARPKD) - AD polycystic liver disease associated with, 595 - congenital hepatic fibrosis associated with, 592 Autosomal recessive polycystic liver disease, Caroli disease associated with, 872

B

Bacillary dysentery, toxic megacolon associated with, 471 Bacterial cholangitis. See Ascending cholangitis. Bacterial infections - Bartonella infection, peliosis hepatis associated with, 724 - bile, gallbladder hydrops and empyema associated with, 894 - duodenitis associated with, 317 - Helicobacter pylori infection. See Helicobacter pylori infection. - infectious colitis associated with, 460 - intestinal, 361 - mesenteric adenitis and enteritis associated with, 357 - mycobacterial intestinal, 361, 362 intestinal lymphangiectasia associated with, 385 - peritonitis associated with, 78 - recurrent pyogenic cholangitis associated with, 880 Bacterial peritonitis, pseudomyxoma peritonei vs., 150 Bariatric surgery, imaging, 280–285 - image gallery, 280, 283–285 - laparoscopic adjustable gastric banding (LAGB) procedure, 281 - laparoscopic Roux-en-Y gastric bypass procedure (RYGB), 281–282 - sleeve gastrectomy, 281 Barotrauma, 48–49 - differential diagnosis, 49 - pneumatosis of intestine vs., 395 v

INDEX - staging, grading, & classification, 49 Barrett esophagus, 170–171 - differential diagnosis, 171 - drug-induced esophagitis vs., 174 - genomic instability, esophageal carcinoma associated with, 230 Bartonella infection, peliosis hepatis associated with, 724 Beckwith-Wiedemann syndrome - nonneoplastic pancreatic cysts associated with, 1032 - umbilical hernia associated with, 103 Behçet disease. See also Vasculitis. - definition, 39, 40 - imaging findings, 39, 40 - toxic megacolon associated with, 471 Benign abdominal neoplasms, 132–139 - desmoid. See Desmoid tumors. - intestinal lymphangiectasia associated with, 385 - lymphangioma (mesenteric cyst). See Lymphangioma (mesenteric cyst). Benign biliary neoplasms. See Gallbladder polyps. Benign biliary stricture - autoimmune (IgG4) cholangitis vs., 932 - Mirizzi syndrome vs., 919 Benign colon neoplasms - colonic polyps, 516–519 colonic diverticulosis vs., 489 differential diagnosis, 518 - villous adenoma. See Villous adenoma, colon. Benign esophageal neoplasms - extrinsic mass, differential diagnosis, 157 - fibrovascular polyp, 226 - inflammatory polyp, 227 - intraluminal mass, differential diagnosis, 157 - intramural benign esophageal tumors. See Intramural benign esophageal tumors. - intrinsic/extrinsic, esophageal achalasia associated with, 182 Benign gastric neoplasms - gastric polyps, 286–289 - intramural benign gastric tumors, 290–293 - "target" or bull's eye-lesions, differential diagnosis, 237 Benign gastric (peptic) ulcer, gastric carcinoma vs., 299 Benign hepatic neoplasms. See Hepatic neoplasms, benign. Benign intramural tumors - colonic, villous adenoma vs., 522 - esophageal. See Intramural benign esophageal tumors. - gastric, 290–293 Benign pancreatic neoplasms - nonneoplastic pancreatic cysts, 1030–1033 - serous cystadenoma. See Pancreatic serous cystadenoma. Benign small intestine neoplasms - hamartomatous polyposis syndrome. See Hamartomatous polyposis syndrome. - ileocecal valve lipoma and lipomatous infiltration, 435 - intramural (mesenchymal) intestinal tumors, 434 Benign splenic neoplasms - primary splenic tumors. See Primary splenic tumors. - splenic cyst. See Splenic cyst. vi

Bezoar. See Gastric bezoar. Bicuspid insufficiency, portal hypertension and varices associated with, 116 Bile - bacterially contaminated, gallbladder hydrops and empyema associated with, 894 - iatrogenic high density, due to cholangiography: vicarious excretion of contrast medium vs., 153 Bile duct - asymmetric dilation of intrahepatic bile duct, differential diagnosis, 856 - common. See Common bile duct. - congenital malformation of, biliary hamartoma associated with, 795 - cyst. See Hepatic cyst. - cystadenocarcinoma. See Biliary cystadenocarcinoma. - dilated or obstructed, peribiliary cysts vs., 677 - gas in bile ducts or gallbladder, differential diagnosis, 855 - intrahepatic, peribiliary cysts vs., 677 - ischemic injury, 942–945 - narrowing, overestimation of, 864 Bile reflux, gastric ulcer associated with, 250 Bile stasis - acalculous cholecystitis associated with, 908 - peripheral (intrahepatic) cholangiocarcinoma associated with, 822 Bilharzia. See Hepatic schistosomiasis. Biliary anomalies, choledochal cyst associated with, 876 Biliary atresia, choledochal cyst associated with, 876 Biliary cirrhosis, primary, 652–657 - associated abnormalities, 654 - autoimmune hepatitis vs., 631 - differential diagnosis, 653 - genetics, 654 - image gallery, 652, 655–657 - sarcoidosis vs., 29 Biliary cystadenocarcinoma, 832–837 - biliary cystadenoma/cystadenocarcinoma, biliary IPMN vs., 967 - differential diagnosis, 833–834 - hepatic amebic abscess vs., 609 - hepatic cyst vs., 765 - hepatic hydatid cyst vs., 613 - hepatic pyogenic abscess vs., 601 - image gallery, 832, 835–837 Biliary cystadenoma - biliary cystadenoma/cystadenocarcinoma, biliary IPMN vs., 967 - malignant transformation: biliary cystadenocarcinoma associated with, 834 Biliary ductal stricture, anastomotic: ischemic bile duct injury vs., 944 Biliary-enteric anastomosis, gas in biliary tree due to: emphysematous cholecystitis vs., 915 Biliary hamartoma, 794–797 - AD polycystic liver disease vs., 595 - Caroli disease vs., 871 - choledochal cyst associated with, 876 - congenital hepatic fibrosis vs., 591

INDEX - differential diagnosis, 795 - hepatic cyst vs., 765 - hepatic TB and fungal infections vs., 605 - HIV/AIDS vs., 10 - image gallery, 794, 796–797 Biliary infection. See Ascending cholangitis. Biliary IPMN (intraductal papillary mucinous neoplasm), 966–969 - associated abnormalities, 968 - differential diagnosis, 967–968 - genetics, 968 - image gallery, 966, 969 - staging, grading, & classification, 968 Biliary metastases and lymphoma, 964 Biliary neoplasms, benign. See Gallbladder polyps. Biliary neoplasms, malignant - ampullary carcinoma, 960–963 differential diagnosis, 961 duodenal polyps vs., 332 - biliary IPMN, 966–969 - biliary metastases and lymphoma, 964 - biliary papillomatosis, 965 - gallbladder carcinoma. See Gallbladder carcinoma. Biliary normal variants and artifacts, 862–865 - differential diagnosis, 863–864 - image gallery, 862, 865 - MRCP artifacts and pitfalls, 863–864 - normal variants most common variants, 863 normal biliary anatomy, 863 pancreaticobiliary junction variants, 863 persistent postoperative dilation of bile ducts, 863 uncommon or rare variants, 863 Biliary obstruction, intrahepatic: focal confluent fibrosis vs., 659 Biliary papillomatosis, 965 - differential diagnosis, 965 - mucin-secreting. See Biliary IPMN (intraductal papillary mucinous neoplasm). Biliary sclerosis. See Chemotherapy-induced cholangitis. Biliary stones - biliary IPMN associated with, 968 - pancreatobiliary parasites vs., 888 Biliary stricture - benign autoimmune (IgG4) cholangitis vs., 932 Mirizzi syndrome vs., 919 - due to nontraumatic causes, biliary trauma vs., 947 - multiple, differential diagnosis, 856 Biliary system, 854–969 - acalculous cholecystitis, 906–909 acute calculous cholecystitis vs., 904 differential diagnosis, 907–908 - acute calculous cholecystitis, 902–905 acalculous cholecystitis vs., 907 differential diagnosis, 904 - AIDS cholangiopathy. See AIDS cholangiopathy. - ascending cholangitis. See Ascending cholangitis. - autoimmune (IgG4) cholangitis. See Autoimmune (IgG4) cholangitis.

- biloma, 938–941 abdominal abscess vs., 73 differential diagnosis, 939 hepatic cyst vs., 766 - Caroli disease. See Caroli disease. - chemotherapy-induced cholangitis, 950–951 ascending cholangitis vs., 883 differential diagnosis, 951 primary sclerosing cholangitis vs., 936 - choledochal cyst. See Choledochal cyst. - congenital abnormalities of gallbladder, 866–869 - differential diagnosis, 855–856 asymmetric dilation of intrahepatic bile ducts, 856 biliary strictures, multiple, 856 diffuse gallbladder wall thickening, 855 dilated common bile duct, 855 distended gallbladder, 855 focal gallbladder wall thickening, 855 gas in bile ducts or gallbladder, 855 high attenuation (hyperdense) bile in gallbladder, 855 - emphysematous cholecystitis. See Emphysematous cholecystitis. - gallbladder hydrops and empyema, 892–895 - gallbladder neoplasms benign. See Gallbladder polyps. malignant. See Biliary neoplasms, malignant. - gallbladder polyps, 952–955 differential diagnosis, 953 gallbladder carcinoma associated with, 957 gallbladder carcinoma vs., 957 - gallstones and sludge. See Gallstones and sludge. - gas in bile ducts or gallbladder, differential diagnosis, 855 - hyperplastic cholecystoses. See Hyperplastic cholecystoses. - imaging approach, 854–861 anatomy (graphic images), 857 differential diagnosis, 855–856 evaluation of jaundiced patient, 854–855 image gallery, 856, 858–861 indications and protocols, 854 - ischemic bile duct injury, 942–945 - milk of calcium bile, 928–929 differential diagnosis, 929 porcelain gallbladder associated with, 927 vicarious excretion of contrast medium vs., 153 - Mirizzi syndrome, 918–921 - neoplasms benign. See Gallbladder polyps. malignant. See Biliary neoplasms, malignant. - normal variants and artifacts, 862–865 - pancreatobiliary parasites, 886–889 - porcelain gallbladder. See Porcelain gallbladder. - primary sclerosing cholangitis. See Primary sclerosing cholangitis. - recurrent pyogenic cholangitis. See Recurrent pyogenic cholangitis. - trauma, 946–949 - xanthogranulomatous cholecystitis, 910–913 differential diagnosis, 911–912 gallbladder carcinoma vs., 957 vii

INDEX hyperplastic cholecystoses vs., 924 Biliary trauma, 946–949 - differential diagnosis, 947 - image gallery, 946, 949 - staging, grading, & classification, 948 Biliary tree - CT findings in HIV/AIDS, 9 - gas in, from biliary-enteric anastomosis or post sphincterotomy: emphysematous cholecystitis vs., 915 - imaging findings, in cystic fibrosis, 19 - obstruction, ascending cholangitis associated with, 883–884 Biloma, 938–941 - abdominal abscess vs., 73 - differential diagnosis, 939 - hepatic cyst vs., 766 - image gallery, 938, 940–941 Bilroth procedures. See Partial gastrectomy: Bilroth procedures. Bladder carcinoma, rectal carcinoma vs., 531 Bladder lesions, tuberculosis vs., 14 Bladder tuberculosis, radiologic findings, 13 Bleeding hepatic tumor - HELLP syndrome vs., 733 - hepatic trauma vs., 737 Blood fluke. See Hepatic schistosomiasis. Blood type A, gastric carcinoma associated with, 300 Bochdalek hernia, 112 - differential diagnosis, 112 - gastric volvulus associated with, 264 - traumatic diaphragmatic rupture vs., 121 Boeck sarcoid. See Sarcoidosis. Boerhaave syndrome, 216–217 - differential diagnosis, 217 - esophageal perforation vs., 213 Bone marrow overproduction of light chain (AL protein), amyloidosis associated with, 27 Bones, CT findings in sickle cell anemia, 23 Bowel - large. See Colon. - small. See Small intestine. Bowel gas in right upper quadrant, emphysematous cholecystitis vs., 916 Bowel injury, hepatic trauma associated with, 738 Bowel necrosis, pneumatosis of intestine vs., 395 Bowel tumor, primary - intussusception vs., 399 - radiation enteritis and colitis vs., 427 Bowel wall thickening, nontraumatic, colorectal trauma vs., 515 Brain neoplasms, focal nodular hyperplasia associated with, 782 BRCA2 gene mutation, pancreatic ductal carcinoma associated with, 1036 Breast carcinoma, duodenal metastases and lymphoma associated with, 339 Brunner gland hyperplasia, 322–323 - differential diagnosis, 323 - duodenal polyps vs., 331 viii

- hamartomatous polyposis syndrome vs., 437 Budd-Chiari syndrome, 710–715 - ascites associated with, 86 - caudate hypertrophy in, hepatomegaly vs., 689 - cirrhosis vs., 644 - differential diagnosis, 711–712 - image gallery, 710, 713–715 - passive hepatic congestion vs., 707 - portal hypertension and varices associated with, 116 - portal vein occlusion vs., 702 - venoocclusive disease vs., 717

C

C1-INH deficiency, acquired: intestinal (angioneurotic) angioedema associated with, 381 Calcifications - abdominal, differential diagnosis, 67 - dystrophic gallbladder mural calcification, porcelain gallbladder associated with, 927 - multiple splenic calcifications, differential diagnosis, 545 - pancreatic, differential diagnosis, 974 Calcified scar, abdominal incision and injection sites associated with, 127–128 Candida albicans, hepatic TB and fungal infections associated with, 605 Candida esophagitis, 162–163 - associated abnormalities, 163 - Barrett esophagus vs., 171 - differential diagnosis, 163 - intramural pseudodiverticulosis associated with, 207 - reflux esophagitis vs., 167 - viral esophagitis vs., 164 Capillary hemangioma. See Hepatic cavernous hemangioma. Carbolic/nitric acid, caustic esophagitis associated with, 173 Carcinoid syndrome, 439 Carcinoid tumor - ampullary, ampullary carcinoma vs., 961 - desmoid neoplasms vs., 139 - sclerosing mesenteritis vs., 81 - type of intramural benign gastric tumor, 292 Carcinoid tumor, small intestine, 438–441 - associated abnormalities, 440 - classification, 440 - differential diagnosis, 440 - image gallery, 438, 441 - intestinal GIST vs., 449 - mastocytosis vs., 369 - small bowel carcinoma vs., 443 Carcinomatosis - peritoneal ascites associated with, 86 omental infarct vs., 90 peritonitis vs., 77 splenosis vs., 571 - sclerosing mesenteritis vs., 82 Cardiac abnormalities, intestinal carcinoid tumor associated with, 440

INDEX Cardiac disease, colonic ileus and Ogilvie syndrome associated with, 510 Cardiac tamponade, ascites associated with, 86 Cardiomyopathy, passive hepatic congestion associated with, 707 Carney triad, gastric GIST associated with, 296 Caroli disease, 870–873 - AD polycystic liver disease vs., 595 - associated abnormalities, 872 - biliary hamartoma vs., 795 - congenital hepatic fibrosis vs., 591 - differential diagnosis, 871–872 - genetics, 872 - hepatic TB and fungal infections vs., 605 - image gallery, 870, 873 - peribiliary cysts vs., 677 - recurrent pyogenic cholangitis vs., 880 "Carpet lesion," colonic, 517–518 Cathartic colon, ulcerative colitis vs., 468 Caudate hypertrophy in Budd-Chiari syndrome, hepatomegaly vs., 689 Caustic esophagitis, 172–173 - Barrett esophagus vs., 171 - differential diagnosis, 173 - radiation esophagitis vs., 175 - reflux esophagitis vs., 167 Caustic gastritis - gastric carcinoma vs., 300 - imaging findings, 245 Caustic gastroduodenal injury, 258 Cavernous hemangioma, hepatic. See Hepatic cavernous hemangioma. Cavitary mesenteric lymph node syndrome, celiac-sprue disease associated with, 366 CCND1 oncogene, duodenal carcinoma associated with, 336 CDKN2A/p16 gene mutations, metastatic melanoma associated with, 60 Cecal carcinoma - appendicitis vs., 480 - mesenteric adenitis and enteritis vs., 35 - mucocele of appendix vs., 485 Cecal diverticulitis - appendicitis vs., 480 - Meckel diverticulum vs., 354 - neutropenic colitis vs., 465 Cecal volvulus, 506–507 - associated abnormalities, 507 - colonic ileus and Ogilvie syndrome vs., 509 - differential diagnosis, 507 Celecoxib (selective COX-2 inhibitor), small bowel NSAID stricture associated with, 383 Celiac-sprue disease, 364–367 - associated abnormalities, 366 - differential diagnosis, 364–365 - esophageal webs associated with, 178 - genetics, 366 - image gallery, 364, 367 - intestinal lymphangiectasia associated with, 385 - intestinal scleroderma vs., 377

- mastocytosis vs., 369 - small bowel carcinoma associated with, 443 - small bowel NSAID stricture vs., 383 - Whipple disease vs., 368 Cellulose, retained oxidized (Surgicel): abdominal abscess vs., 74 Cervical carcinoma, rectal carcinoma vs., 531 Cervical osteophytes, cricopharyngeal achalasia vs., 179 CFC1 gene mutation, asplenia and polysplenia associated with, 552 CFTR gene mutation - acute pancreatitis associated with, 992 - chronic pancreatitis associated with, 1002 - cystic fibrosis associated with, 20 Chagas disease of esophagus, 165 - differential diagnosis, 165 - esophageal achalasia associated with, 182 Chance fracture, in mesenteric and small bowel trauma, 417 Chemotherapy - ischemic enteritis associated with, 413 - nodular regenerative hyperplasia associated with, 664 - viral esophagitis associated with, 164 Chemotherapy-induced cholangitis, 950–951 - ascending cholangitis vs., 883 - differential diagnosis, 951 - primary sclerosing cholangitis vs., 936 - risk factors, 951 Childbirth, Boerhaave syndrome associated with, 217 Cholangiocarcinoma - biliary IPMN vs., 967 - distal common bile duct, ampullary carcinoma vs., 961 - mucin-producing. See Biliary IPMN (intraductal papillary mucinous neoplasm). - peripheral. See Peripheral (intrahepatic) cholangiocarcinoma. Cholangiopathy, AIDS-related. See AIDS cholangiopathy. Cholangitis - acute pyogenic, AIDS cholangiopathy vs., 891 - AIDS-related, ascending cholangitis vs., 883 - ascending. See Ascending cholangitis. - autoimmune (IgG4). See Autoimmune (IgG4) cholangitis. - chemotherapy-induced. See Chemotherapy-induced cholangitis. - gas-forming, emphysematous cholecystitis vs., 915 - ischemic, AIDS cholangiopathy vs., 891 - primary sclerosing. See Primary sclerosing cholangitis. - recurrent pyogenic. See Recurrent pyogenic cholangitis. Cholecystectomy - hepatic infarction associated with, 719 - laparoscopic or open, biliary trauma associated with, 948 - prior, congenital gallbladder abnormalities vs., 867 Cholecystitis - acalculous, 906–909 acute calculous cholecystitis vs., 904 differential diagnosis, 907–908 - acute calculous, 902–905 acalculous cholecystitis vs., 907 differential diagnosis, 904 ix

INDEX acute, Mirizzi syndrome associated with, 920 chronic. See Chronic cholecystitis. complicated, gallbladder carcinoma vs., 957 duodenitis vs., 317 emphysematous. See Emphysematous cholecystitis. gangrenous gallbladder hydrops and empyema vs., 893 xanthogranulomatous cholecystitis vs., 911 - xanthogranulomatous, 910–913 Cholecysto-choledochal fistula, Mirizzi syndrome associated with, 920 Cholecystoses, hyperplastic, 922–925 - acalculous cholecystitis vs., 908 - associated abnormalities, 924 - congenital gallbladder abnormalities vs., 868 - differential diagnosis, 924 - image gallery, 922, 925 Choledochal cyst, 874–877 - associated abnormalities, 876 - Caroli disease associated with, 872 - classification, 875 - congenital absence of hepatic segments associated with, 599 - differential diagnosis, 875–876 - gallbladder hydrops and empyema vs., 893 - image gallery, 874, 877 - peripheral (intrahepatic) cholangiocarcinoma associated with, 822 Choledocholithiasis - biliary papillomatosis vs., 965 - ischemic bile duct injury vs., 944 - Mirizzi syndrome vs., 919 Cholelithiasis. See also Gallstones. - gallbladder carcinoma associated with, 957 - milk of calcium bile associated with, 929 Cholera, toxic megacolon associated with, 471 Cholesterolosis, hyperplastic cholecystoses associated with, 924 Chromosome 6p, congenital hepatic fibrosis associated with, 592 Chromosome 7, autosomal recessive gene on: cystic fibrosis associated with, 20 Chromosome 19 gene mutation, hamartomatous polyposis syndrome associated with, 437 Chronic active hepatitis. See Autoimmune hepatitis. Chronic advanced liver disease, pancreatic lipomatous pseudohypertrophy associated with, 1013 Chronic alcoholism, intramural pseudodiverticulosis associated with, 207 Chronic cholecystitis - congenital gallbladder abnormalities vs., 867 - gallbladder carcinoma vs., 957 - hyperplastic cholecystoses vs., 924 - intramural hemorrhage from, porcelain gallbladder associated with, 927 - milk of calcium bile associated with, 929 Chronic constipation - cecal volvulus associated with, 507 - sigmoid volvulus associated with, 503 -

x

Chronic gallbladder infection, gallbladder carcinoma associated with, 957 Chronic gallbladder outlet obstruction, gallbladder hydrops and empyema associated with, 894 Chronic gastroesophageal reflux, esophageal webs associated with, 178 Chronic inflammatory diseases, amyloidosis associated with, 27 Chronic obstructive pulmonary disease - duodenal ulcer associated with, 320 - liver displacement by, hepatomegaly vs., 689 - pancreatic lipomatous pseudohypertrophy associated with, 1013 - pneumatosis of intestine vs., 395 Chronic pancreatitis, 1000–1003 - agenesis of dorsal pancreas vs., 980 - autoimmune (IgG4) pancreatitis vs., 1009 - cystic fibrosis vs., 20 - differential diagnosis, 1002 - genetics, 1002 - image gallery, 1000, 1003 - pancreas divisum vs., 983 - pancreatic ductal carcinoma vs., 1036 - pancreatic intraductal papillary mucinous neoplasm (IPMN) vs., 1049 Chronic remnant gastritis, complication of partial gastrectomy, 272 Chronic renal failure - ascites associated with, 86 - duodenal ulcer associated with, 320 - ischemic colitis associated with, 476 Ciliated hepatic foregut cyst, hepatic cyst vs., 766 Cirrhosis, 642–651 - arterioportal shunt associated with, 697 - ascites associated with, 86 - biliary. See Biliary cirrhosis, primary. - Budd-Chiari syndrome vs., 711–712 - congenital absence of hepatic segments vs., 599 - differential diagnosis, 644 - esophageal varices associated with, 200 - hemochromatosis associated with, 681 - hepatic schistosomiasis vs., 617 - hepatocellular carcinoma associated with, 808 - hereditary hemorrhagic telangiectasia vs., 727 - image gallery, 642, 646–651 - passive hepatic congestion vs., 707 - portal hypertension and varices associated with, 116 - portal vein occlusion associated with, 702 - postnecrotic (viral) or alcoholic, primary biliary cirrhosis vs., 653 - postoperative changes of liver vs., 746 - regenerative and dysplastic nodules associated with, 670 - staging, grading, & classification, 644 Cirrhosis, primary biliary, 652–657 - associated abnormalities, 654 - autoimmune hepatitis vs., 631 - differential diagnosis, 653 - genetics, 654 - image gallery, 652, 655–657

INDEX - sarcoidosis vs., 29 Clonorchiasis - biliary IPMN associated with, 968 - pancreatobiliary. See Pancreatobiliary parasites. - peripheral (intrahepatic) cholangiocarcinoma associated with, 822 Closed loop bowel obstruction - ischemic enteritis associated with, 413 - paraduodenal hernia vs., 105 - transmesenteric postoperative hernia vs., 110 Clostridium difficile colitis. See Infectious colitis. Coagulopathy - HELLP syndrome vs., 733 - hepatic trauma vs., 737 - mesenteric and small bowel trauma vs., 417 Coccidioidomycosis, infectious lymphadenopathy from: superior vena cava obstruction associated with, 37 Coffee, gastric ulcer associated with, 250 Colitis - amebic, hepatic amebic abscess associated with, 609 - colorectal trauma vs., 515 - Crohn colitis, neutropenic colitis vs., 465 - granulomatous (Crohn disease) infectious colitis vs., 459 ischemic colitis vs., 476 ulcerative colitis vs., 467 - infectious. See Infectious colitis. - intussusception associated with, 400 - ischemic. See Ischemic colitis. - necrotizing, colon carcinoma associated with, 526 - necrotizing enterocolitis, pneumatosis of intestine vs., 395 - neutropenic (typhlitis), 464–465 differential diagnosis, 465 ulcerative colitis vs., 468 - pseudomembranous, diverticulitis vs., 494 - radiation. See Radiation enteritis and colitis. - ulcerative colitis. See Ulcerative colitis. Collapsed cava sign, in systemic hypotension, 35 Collar sign, in traumatic diaphragmatic rupture, 121 Colocolic fistula, 406 Colon, 452–541 - appendicitis. See Appendicitis. - bowel wall thickening, nontraumatic, colorectal trauma vs., 515 - cecal volvulus, 506–507 colonic ileus and Ogilvie syndrome vs., 509 differential diagnosis, 507 - colitis. See Colitis. - colorectal trauma, 514–515 - CT findings amyloidosis, 27 HIV/AIDS, 9 - differential diagnosis, 453–454 acute right lower quadrant pain, 454 colonic fistula, 453 colonic ileus or dilatation, 453 colonic submucosal wall thickening, 454 mass or inflammation of ileocecal area, 453 segmental colonic narrowing, 453–454 smooth ahaustral colon, 454

solitary colonic filling defect, 453 - distal obstruction cecal volvulus vs., 507 sigmoid volvulus vs., 503 - distention, cecal volvulus associated with, 507 - diverticulitis. See Colonic diverticulitis. - diverticulosis, 488–491 colonic polyps vs., 518 differential diagnosis, 489 - epiploic appendagitis. See Epiploic appendagitis. - fecal impaction and stercoral ulceration, 512 colonic ileus and Ogilvie syndrome vs., 510 differential diagnosis, 512 - fistula, differential diagnosis, 453 - ileus and Ogilvie syndrome, 508–511 cecal volvulus vs., 507 differential diagnosis, 509–510 ileus or dilation, differential diagnosis, 453 ileus vs., 387 - imaging approach, 452–457 anatomy (graphic images), 454–455 approach to abnormal colon, 452–453 differential diagnosis, 453–454 embryology and congenital malformations, 452 gross anatomy, 452 image gallery, 456–457 imaging issues, 452 mural anatomy, 452 - infectious colitis. See Infectious colitis. - ischemic colitis. See Ischemic colitis. - mucocele of appendix, 484–487 appendiceal tumors vs., 540 differential diagnosis, 485 - neoplasms. See Colon neoplasms, benign; Colon neoplasms, malignant. - neutropenic colitis (typhlitis), 464–465 differential diagnosis, 465 ulcerative colitis vs., 468 - obstruction. See Colonic obstruction. - pneumatosis, differential diagnosis, 344 - pressure gradient between lumen and serosa colonic diverticulitis associated with, 494 colonic diverticulosis associated with, 489 - rectal prolapse and intussusception, 513 - segmental narrowing, differential diagnosis, 453–454 - sigmoid volvulus. See Sigmoid volvulus. - smooth ahaustral, differential diagnosis, 454 - solitary colonic filling defect, differential diagnosis, 453 - submucosal wall thickening, differential diagnosis, 454 - toxic megacolon. See Toxic megacolon. - ulcerative colitis. See Ulcerative colitis. Colon adenocarcinoma - metastatic, metastatic melanoma vs., 60 - mucocele of appendix associated with, 485 Colon carcinoma, 524–529 - associated abnormalities, 526 - colonic ileus and Ogilvie syndrome vs., 509 - colonic polyps vs., 518 - differential diagnosis, 525 - diverticulitis vs., 493 - family history, 526 xi

INDEX - fecal impaction and stercoral ulceration vs., 512 - genetics, 526 - ileocecal valve lipoma and lipomatous infiltration vs., 435 - image gallery, 524, 527–529 - ischemic colitis vs., 476 - risk factors, 526 - staging, grading, & classification, 526 - villous adenoma vs., 521–522 Colon neoplasms, benign - colonic polyps, 516–519 colonic diverticulosis vs., 489 differential diagnosis, 518 - villous adenoma. See Villous adenoma, colon. Colon neoplasms, malignant - adenocarcinoma metastatic, metastatic melanoma vs., 60 mucocele of appendix associated with, 485 - appendiceal tumors. See Appendiceal tumors. - carcinoma. See Colon carcinoma. - duodenal metastases and lymphoma associated with, 339 - familial polyposis and Gardner syndrome. See Familial polyposis and Gardner syndrome. - invasion by adjacent tumor, rectal carcinoma vs., 531 - metastases and lymphoma, 541 differential diagnosis, 541 familial polyposis and Gardner syndrome vs., 535 - primary bowel tumor, intussusception vs., 399 - rectal carcinoma, 530–533 Colonic diverticulitis, 492–497 - colon carcinoma vs., 525 - colonic diverticulosis vs., 489 - differential diagnosis, 493–494 - epiploic appendagitis vs., 499 - image gallery, 492, 495–497 Colonic diverticulosis, 488–491 - associated abnormalities, 489–490 - colonic polyps vs., 518 - differential diagnosis, 489 - image gallery, 488, 491 - staging, grading, & classification, 490 Colonic ileus and Ogilvie syndrome, 508–511 - cecal volvulus vs., 507 - differential diagnosis, 509–510 - ileus or dilation, differential diagnosis, 453 - ileus vs., 387 - image gallery, 508, 511 Colonic metastases and lymphoma, 541 - differential diagnosis, 541 - familial polyposis and Gardner syndrome vs., 535 Colonic obstruction - distal cecal volvulus vs., 507 sigmoid volvulus vs., 503 - functional or idiopathic. See Colonic ileus and Ogilvie syndrome. - small bowel obstruction vs., 390 - toxic megacolon vs., 471 Colonic polyps, 516–519 - colonic diverticulosis vs., 489 xii

- differential diagnosis, 518 - image gallery, 516, 519 - types, 517–518 Colonic pseudoobstruction. See Colonic ileus and Ogilvie syndrome. Colonic transverse loop hernia, gastric volvulus associated with, 264 Colorectal carcinoids, 439 Colorectal carcinoma, colon carcinoma associated with, 526 Colorectal trauma, 514–515 Colovaginal fistula, 406 Colovesical fistula to thick-walled bladder, 406 Common bile duct. See also Bile duct. - dilated, differential diagnosis, 855 - distal cholangiocarcinoma, ampullary carcinoma vs., 961 impacted stone, 864 - obstruction, malignant: choledochal cyst vs., 875–876 - pseudodilatation, 864 Common hepatic duct obstruction, due to enlarged regional nodes: Mirizzi syndrome vs., 919 Complicated cholecystitis, gallbladder carcinoma vs., 957 Confluent hepatic fibrosis Congenital abdominal wall defect - femoral hernia associated with, 97 - inguinal hernia associated with, 94 Congenital absence of hepatic segments, 598–599 - associated abnormalities, 599 - differential diagnosis, 599 - postoperative changes of liver vs., 746 Congenital angiomatous malformation, peliosis hepatis associated with, 724 Congenital defect - Bochdalek hernia associated with, 112 - transmesenteric postoperative hernia associated with, 109 Congenital diaphragmatic hernias, traumatic diaphragmatic rupture vs., 121 Congenital gallbladder abnormalities, 866–869 - associated abnormalities, 868 - definitions, 867 - differential diagnosis, 867–868 - image gallery, 866, 869 - staging, grading, & classification, 868 Congenital hepatic fibrosis, 590–593 - AD polycystic liver disease associated with, 595 - associated abnormalities, 592 - Caroli disease associated with, 872 - choledochal cyst associated with, 876 - differential diagnosis, 591 - genetics, 592 - image gallery, 590, 593 Congenital malformation of bile ducts, biliary hamartoma associated with, 795 Congenital mesenteric anomaly, paraduodenal hernia associated with, 106 Congenital pancreatic cyst. See Nonneoplastic pancreatic cysts.

INDEX Congested liver in cardiac disease. See Passive hepatic congestion. Congestive disorders, splenomegaly and hypersplenism associated with, 559, 560 Congestive heart failure - ascites associated with, 86 - hepatomegaly associated with, 689 - intestinal lymphangiectasia associated with, 385 - omental infarct associated with, 90 - passive hepatic congestion associated with, 707 Constipation, chronic - cecal volvulus associated with, 507 - sigmoid volvulus associated with, 503 Constrictive pericarditis - ascites associated with, 86 - hepatomegaly associated with, 689 - nodular regenerative hyperplasia associated with, 664 - passive hepatic congestion associated with, 707 - portal hypertension and varices associated with, 116 Contrast enhancement, with normal hepatic blood supply: transient hepatic attenuation or intensity difference associated with, 691 Copper metabolism disorders, Wilson disease associated with, 685 Corrosive esophagitis. See Caustic esophagitis. Coughing, Boerhaave syndrome associated with, 217 Courvoisier gallbladder, gallbladder hydrops and empyema vs., 893 Cowden syndrome (multiple hamartoma). See Hamartomatous polyposis syndrome. CREST syndrome - esophageal scleroderma, 189 - intestinal scleroderma, 377 Cricopharyngeal achalasia, 179 Cricopharyngeal dysfunction, Zenker diverticulum associated with, 204 Crohn colitis, neutropenic colitis vs., 465 Crohn disease, 370–375. See also Granulomatous colitis (Crohn disease). - appendicitis vs., 480 - associated abnormalities, 372 - celiac-sprue disease vs., 365 - chronic or cicatrizing phase, 371 - differential diagnosis, 371–372 - duodenal carcinoma vs., 335 - duodenitis associated with, 317 - enteric fistulas and sinus tracts associated with, 406 - gastritis associated with, 245 - genetics, 372 - image gallery, 370, 373–375 - intestinal metastases and lymphoma vs., 446 - intestinal parasites and infestation vs., 359 - ischemic enteritis vs., 413 - Meckel diverticulum vs., 353 - mesenteric adenitis and enteritis vs., 35 - noncicatrizing, acute phase, 371 - primary sclerosing cholangitis associated with, 936 - radiation enteritis and colitis vs., 427 - small bowel carcinoma vs., 443 - small bowel diverticula vs., 351

- small bowel NSAID stricture vs., 383 - with fistula, 406 - Zollinger-Ellison syndrome vs., 251 Cronkhite-Canada syndrome. See also Hamartomatous polyposis syndrome. - colonic polyps associated with, 518 Crural hernia. See Femoral hernia. Cryptosporidium infection, intestinal, 361, 362 CTNNB1 gene mutation, gallbladder carcinoma associated with, 958 Cushing ulcer, gastric ulcer associated with, 250 Cutaneous angioedema, intestinal (angioneurotic) angioedema associated with, 381 Cyclophosphamide, hepatic angiosarcoma associated with, 839 Cystadenocarcinoma - biliary. See Biliary cystadenocarcinoma. - mucinous cystadenoma or cystadenocarcinoma. See Mucinous cystic pancreatic tumor. Cystadenoma - biliary cystadenoma/cystadenocarcinoma, biliary IPMN vs., 967 - biliary, malignant transformation: biliary cystadenocarcinoma associated with, 834 - hepatobiliary. See Biliary cystadenocarcinoma. - mucinous cystadenoma or cystadenocarcinoma. See Mucinous cystic pancreatic tumor. - pancreatic. See Pancreatic serous cystadenoma. Cystic duct, stone impaction in, Mirizzi syndrome associated with, 920 Cystic dystrophy of duodenal wall. See Groove pancreatitis. Cystic fibrosis, 18–21 - appendicitis vs., 480 - chronic pancreatitis associated with, 1002 - differential diagnosis, 20 - image gallery, 18, 21 - mucocele of appendix vs., 485 - nonneoplastic pancreatic cysts associated with, 1032 - pancreatic lipomatous pseudohypertrophy vs., 1013 - small bowel obstruction vs., 390 - steatosis and steatohepatitis associated with, 634 Cystic lymphangioma. See Lymphangioma (mesenteric cyst). Cystic metastases - AD polycystic liver disease vs., 595 - hepatic hydatid cyst vs., 613 Cystic pancreatic mass, differential diagnosis, 973 Cystic pancreatic neuroendocrine tumors - mucinous cystic pancreatic tumor vs., 1043 - nonneoplastic pancreatic cysts vs., 1031–1032 Cystic splenic masses, differential diagnosis, 545 Cysts - choledochal. See Choledochal cyst. - ciliated hepatic foregut cyst, hepatic cyst vs., 766 - cyst or cystic tumor, arising from visceral organ: lymphangioma (mesenteric cyst) vs., 133 - duplication cysts. See Duplication cysts. - hemorrhagic or infected cyst, hepatic hydatid cyst vs., 613 xiii

INDEX - hepatic. See Hepatic cyst. - hepatic hydatid cyst. See Hepatic hydatid cyst. - lymphangioma (mesenteric cyst). See Lymphangioma (mesenteric cyst). - nonneoplastic pancreatic cysts, 1030–1033 differential diagnosis, 1031 mucinous cystic pancreatic tumor vs., 1044 - ovarian, peritoneal inclusion cyst vs., 131 - paraovarian, peritoneal inclusion cyst vs., 131 - periampullary duodenal wall cyst. See Groove pancreatitis. - peribiliary, 677 - peritoneal inclusion cyst. See Peritoneal inclusion cyst. - splenic. See Splenic cyst. Cytokine-mediated inflammatory factors, ileus associated with, 387 Cytomegalovirus esophagitis, Candida esophagitis associated with, 163 Cytomegalovirus infection - intestinal, 361, 362 - post-transplant lymphoproliferative disorder associated with, 52

D

Dangling diaphragm sign, 121 DCC gene deletion, colon carcinoma associated with, 526 Deep fibromatosis. See Desmoid tumors. Defecation, Boerhaave syndrome associated with, 217 Delayed emptying of conduit, post-esophagectomy, 220 Delayed gastric emptying - complication of pancreatic surgery, 1020 - gastric ulcer associated with, 250 Dermatitis herpetiformis, celiac-sprue disease associated with, 366 Dermatomyositis - esophageal scleroderma associated with, 190 - intestinal scleroderma associated with, 378 Desmoid tumors, 136–139 - abdominal incision and injection sites vs., 128 - differential diagnosis, 137–138 - image gallery, 136, 139 - sclerosing mesenteritis vs., 82 Diabetes mellitus - abdominal abscess associated with, 74 - hepatic adenoma associated with, 787 - intramural pseudodiverticulosis associated with, 207 - pancreatic ductal carcinoma associated with, 1036 - steatosis and steatohepatitis associated with, 634 Diabetic lipodystrophy, associated with abdominal incision and injection sites, 127 Diabetic neuropathy, Chagas disease of esophagus vs., 165 Dialysis-related amyloidosis, 27 Diaphragm disease. See Small bowel NSAID stricture. Diaphragmatic eventration and paralysis, 152 - Bochdalek hernia vs., 112 - gastric volvulus associated with, 264 - traumatic diaphragmatic rupture vs., 121 Diaphragmatic hernia - malrotation of small intestine associated with, 349 xiv

- post-esophagectomy, 220 Diaphragmatic rupture, traumatic, 120–123 Diet - heavy with nitrites or nitrates, gastric carcinoma associated with, 300 - high fat, pancreatic ductal carcinoma associated with, 1036 - low in fiber colonic diverticulosis associated with, 489 sigmoid volvulus associated with, 503 - nitrites or nitrates, gastric carcinoma associated with, 300 Diethylstilbestrol, hepatic angiosarcoma associated with, 839 Diffuse esophageal spasm, form of esophageal motility disturbance, imaging, 185 Diffuse fatty replacement of pancreas, asymmetric fatty lobulation of pancreas vs., 987 Diffuse lymphoma, viral hepatitis vs., 622 Digitalis, omental infarct associated with, 90 Dilated common bile duct, differential diagnosis, 855 Dilated duodenum, differential diagnosis, 310 Dilated esophagus, differential diagnosis, 157 Dilated small bowel, cluster of: differential diagnosis, 343 Dilation of small bowel lumen, complication of small intestine transplantation, 432 Disabilities, sigmoid volvulus associated with, 503–504 Disseminated vascular coagulation, HELLP syndrome associated with, 734 Distal colon obstruction - cecal volvulus vs., 507 - sigmoid volvulus vs., 503 Distal common bile duct - cholangiocarcinoma, ampullary carcinoma vs., 961 - impacted stone, 864 Diverticula/diverticulum - anatomical considerations, 236 - differential diagnosis, 243 - duodenal, 315 choledochal cyst vs., 876 differential diagnosis, 315 duodenal ulcer vs., 319 - esophageal. See Esophageal diverticula. - gastric, 242–243 - giant sigmoid diverticulum, colonic diverticulosis vs., 489 - Killian-Jamieson diverticulum, Zenker diverticulum vs., 203 - Meckel diverticulum. See Meckel diverticulum. - pulsion. See Pulsion diverticulum. - small bowel, 351 - traction, 208 differential diagnosis, 208 pulsion diverticulum vs., 209 - Zenker diverticulum, 202–205 differential diagnosis, 203–204 traction diverticulum vs., 208 Diverticular disease. See Colonic diverticulosis.

INDEX Diverticulitis - cecal appendicitis vs., 480 Meckel diverticulum vs., 354 neutropenic colitis vs., 465 - colonic. See Diverticulitis, colonic. - enteric fistulas and sinus tracts associated with, 406 - hepatic flexure, acute calculous cholecystitis vs., 904 - hepatic pyogenic abscess associated with, 601 - ischemic colitis vs., 475 - ulcerative colitis vs., 468 - with fistula, 406 - with septic portal venous occlusion liver abscess, transient hepatic attenuation or intensity difference associated with, 692 Diverticulitis, colonic, 492–497 - colon carcinoma vs., 525 - colonic diverticulosis vs., 489 - differential diagnosis, 493–494 - epiploic appendagitis vs., 499 - image gallery, 492, 495–497 Diverticulosis, colonic, 488–491 - associated abnormalities, 489–490 - colonic polyps vs., 518 - differential diagnosis, 489 - image gallery, 488, 491 - staging, grading, & classification, 490 Diverticulum. See Diverticula/diverticulum. Dorsal pancreas agenesis. See Agenesis of dorsal pancreas. Down syndrome, umbilical hernia associated with, 103 Drain cleaner, caustic esophagitis associated with, 173 Dropped gallstone, gallstone ileus vs., 403 Drug-induced esophagitis, 174 - Barrett esophagus vs., 171 - differential diagnosis, 174 - reflux esophagitis vs., 167 - viral esophagitis vs., 164 Drugs - amiodarone therapy, hemochromatosis vs., 681 - chronic pancreatitis associated with, 1002 - ischemic enteritis associated with, 413 - steatosis and steatohepatitis associated with, 634 Dumping syndrome, complication of partial gastrectomy, 271 Duodenal adenocarcinoma. See Duodenal carcinoma. Duodenal atresia, malrotation of small intestine associated with, 349 Duodenal carcinoid, duodenal carcinoma vs., 335 Duodenal carcinoma, 334–337 - annular pancreas vs., 981 - differential diagnosis, 335 - duodenal metastases and lymphoma vs., 339 - duodenal polyps vs., 332 - duodenal ulcer vs., 319 - genetics, 336 - groove pancreatitis vs., 1004 - image gallery, 334, 337 - pancreatic ductal carcinoma vs., 1036 - periampullary, ampullary carcinoma vs., 961 - staging, grading, & classification, 336

Duodenal diverticulum, 315 - choledochal cyst vs., 876 - differential diagnosis, 315 - duodenal ulcer vs., 319 Duodenal filling defects, differential diagnosis, 311 Duodenal fistula, 406 Duodenal flexure pseudotumor, 314 - Brunner gland hyperplasia vs., 323 - duodenal polyps vs., 332 Duodenal GIST, duodenal metastases and lymphoma vs., 339 Duodenal hamartoma, duodenal polyps vs., 332 Duodenal hematoma, duodenal ulcer vs., 320 Duodenal inflammation, duodenal ulcer vs., 319 Duodenal injury, without pancreatic injury: pancreatic trauma vs., 1015 Duodenal lymphoma, duodenal carcinoma vs., 335 Duodenal metastases and lymphoma, 338–339 - associated abnormalities, 339 - Brunner gland hyperplasia vs., 323 - differential diagnosis, 339 - gastroduodenal trauma vs., 327 - staging, grading, & classification, 339 Duodenal neoplasms, benign - duodenal polyps, 330–333 - intramural or extrinsic mass, differential diagnosis, 310 Duodenal neoplasms, malignant - duodenal carcinoma. See Duodenal carcinoma. - duodenal metastases and lymphoma. See Duodenal metastases and lymphoma. - secondary invasion, duodenal metastases and lymphoma vs., 339 Duodenal obstruction, SMA (superior mesenteric artery) syndrome vs., 325 Duodenal polyps, 330–333 - associated abnormalities, 332 - differential diagnosis, 331–332 - genetics, 332 - image gallery, 330, 333 - submucosal (intramural) lesions, imaging findings, 331 - types, 331 Duodenal stenosis - malrotation of small intestine associated with, 349 - other causes, annular pancreas vs., 981 Duodenal stricture - duodenal ulcer vs., 319 - SMA (superior mesenteric artery) syndrome vs., 325 Duodenal stump leakage, complication of partial gastrectomy, 271 Duodenal trauma, pancreatic trauma associated with, 1016 Duodenal ulcer, 318–321 - acute calculous cholecystitis vs., 904 - differential diagnosis, 319–320 - duodenal carcinoma vs., 335 - genetics, 320 - image gallery, 318, 321 - penetrating, aortoenteric fistula associated with, 329 - perforated acute pancreatitis and complications vs., 992 xv

INDEX barotrauma vs., 49 gastroduodenal trauma vs., 327 - postbulbar, annular pancreas vs., 981 Duodenal wall - cystic dystrophy of. See Groove pancreatitis. - pancreatic hamartoma of. See Groove pancreatitis. Duodenal wall cyst, periampullary. See Groove pancreatitis. Duodenitis, 316–317 - associated abnormalities, 317 - Brunner gland hyperplasia vs., 323 - differential diagnosis, 317 Duodenum, 310–339 - anatomical/congenital anomalies, SMA (superior mesenteric artery) syndrome associated with, 325 - aortoenteric fistula, 328–329 - Brunner gland hyperplasia, 322–323 differential diagnosis, 323 duodenal polyps vs., 331 hamartomatous polyposis syndrome vs., 437 - differential diagnosis, 310–311 dilated duodenum, 310 duodenal filling defects, 311 duodenal intramural or extrinsic mass, 310 thickened duodenal folds, 310–311 - dilated, differential diagnosis, 310 - duodenal diverticulum, 315 choledochal cyst vs., 876 differential diagnosis, 315 duodenal ulcer vs., 319 - duodenal flexure pseudotumor, 314 Brunner gland hyperplasia vs., 323 duodenal polyps vs., 332 - duodenal ulcer. See Duodenal ulcer. - duodenitis, 316–317 Brunner gland hyperplasia vs., 323 differential diagnosis, 317 - filling defects, differential diagnosis, 311 - gastroduodenal trauma, 326–327 differential diagnosis, 327 duodenal carcinoma vs., 335 - imaging approach, 310–313 anatomy (graphic images), 311 anatomy and terminology, 310 differential diagnosis, 310–311 image gallery, 312–313 imaging anatomy, 310 imaging protocols, 310 - neoplasms. See Duodenal neoplasms, benign; Duodenal neoplasms, malignant. - SMA (superior mesenteric artery) syndrome, 324–325 differential diagnosis, 325 intestinal scleroderma vs., 377 - thickened folds, differential diagnosis, 310–311 Duplication cysts - enteric, duodenal carcinoma vs., 335 - epidermoid, splenic cyst associated with, 573 - gastrointestinal lymphangioma (mesenteric cyst), 133 small intestine duplication cyst vs., 350 - small intestine, 350 xvi

E

Echinococcosis - pancreatobiliary. See Pancreatobiliary parasites. - splenic infection and abscess associated with, 556 Echinococcus granulosus and Echinococcus multilocularis, hepatic hydatid cyst associated with, 613 Eclampsia, HELLP syndrome associated with, 733 Ectopic gastric mucosa, duodenal polyps vs., 332 Ectopic pancreatic tissue, 988–989 - differential diagnosis, 989 - gastric diverticulum vs., 243 - gastric polyps vs., 288 - intramural benign gastric tumors vs., 291 - intramural (mesenchymal) intestinal tumors vs., 434 Edema - generalized, Ménétrier disease associated with, 257 - mesenteric, sclerosing mesenteritis vs., 81–82 Edematous pancreatitis - acute autoimmune (IgG4) pancreatitis vs., 1009 involving groove, groove pancreatitis vs., 1004 - interstitial, 991 Ehlers-Danlos syndrome, umbilical hernia associated with, 103 Electrolyte disturbance - colonic ileus and Ogilvie syndrome associated with, 510 - ileus associated with, 387 Embolic events, ischemic enteritis associated with, 413 Embryonal sarcoma, undifferentiated. See Undifferentiated sarcoma, hepatic. Emphysematous cholecystitis, 914–917 - differential diagnosis, 915–916 - gallbladder hydrops and empyema vs., 893 - gallstones and sludge vs., 898 - image gallery, 914, 917 - porcelain gallbladder vs., 927 - staging, grading, & classification, 916 Emphysematous gastritis, 245 Empyema of gallbladder. See Gallbladder hydrops and empyema. Endometrial implant, intussusception vs., 399 Endometrial implantation in abdominal incision, 128 Endometriosis, colon carcinoma vs., 525 Endoscopic procedures - esophageal perforation associated with, 214 - pneumatosis of intestine vs., 395 Entamoeba histolytica, hepatic amebic abscess associated with, 609 Enteric duplication cyst, duodenal carcinoma vs., 335 Enteric fistulas and sinus tracts, 404–411 Enteric perforation, abdominal abscess associated with, 74 Enteritis - ischemic. See Ischemic enteritis. - mesenteric. See Mesenteric adenitis and enteritis. - radiation. See Radiation enteritis and colitis. Enterochromaffin cells of Kulchitsky, intestinal carcinoid tumor associated with, 440 Enterocolic fistula, 406

INDEX Enterocutaneous fistula - abdominal incision and injection sites vs., 128 - fluoroscopic findings, 406 Enteroenteric fistula, 406 Enteromerocele. See Femoral hernia. Enudation of pancreas, 1019 Environmental factors - gastric carcinoma associated with, 300 - hepatic angiosarcoma associated with, 839 - intestinal scleroderma associated with, 378 Eosinophilic esophagitis, 176 - differential diagnosis, 176 - esophageal webs associated with, 178 Eosinophilic gastritis - imaging findings, 245 - Zollinger-Ellison syndrome vs., 251 Eosinophilic gastroenteritis, 176 Epidermoid cyst, splenic cyst associated with, 573 Epidermolysis and pemphigoid of esophagus, 177 - esophageal webs associated with, 178 - Zenker diverticulum vs., 204 Epigastric pain, differential diagnosis, 238 Epiphrenic diverticulum. See Pulsion diverticulum. Epiploic appendagitis, 498–501 - differential diagnosis, 499–500 - image gallery, 498, 501 - intussusception associated with, 400 - omental infarct vs., 89 Epithelial pancreatic cyst. See Nonneoplastic pancreatic cysts. Epithelioid hemangioendothelioma, 826–831 - differential diagnosis, 827–828 - focal confluent fibrosis vs., 659 - image gallery, 826, 829–831 Epstein-Barr virus - leukemia and lymphoma associated with, 56 - mononucleosis associated with, 17 - post-transplant lymphoproliferative disorder associated with, 52 - viral hepatitis associated with, 622 ERBB2 oncogene, duodenal carcinoma associated with, 336 Erosive gastritis, 245 Esophageal achalasia, 180–183 - associated abnormalities, 182 - Chagas disease of esophagus vs., 165 - cricopharyngeal achalasia, 179 - differential diagnosis, 181–182 - esophageal scleroderma vs., 189 - form of esophageal motility disturbance, imaging, 185 - image gallery, 180, 183 - Zenker diverticulum associated with, 204 Esophageal candidiasis. See Candida esophagitis. Esophageal carcinoma, 228–231 - achalasia vs., 181 - Barrett esophagus vs., 171 - caustic esophagitis vs., 173 - differential diagnosis, 229–230 - drug-induced esophagitis vs., 174 - esophageal perforation associated with, 214 - fibrovascular polyp vs., 226

- foreign body vs., 211 - genetics, 230 - image gallery, 228, 231 - intramural benign esophageal tumors vs., 225 - metastases and lymphoma vs., 233 - motility disturbances vs., 185 - portal hypertension and varices vs., 116 - Schatzki ring vs., 193 - scleroderma vs., 189 - staging, grading, & classification, 230 - varices vs., 199 Esophageal diverticula - differential diagnosis, 157 - esophageal perforation vs., 213 - intramural pseudodiverticulosis, 206–207 - pulsion diverticulum. See Pulsion diverticulum. - traction diverticulum, 208 differential diagnosis, 208 pulsion diverticulum vs., 209 - Zenker diverticulum, 202–205 differential diagnosis, 203–204 traction diverticulum vs., 208 Esophageal foreign body, 210–211 - differential diagnosis, 211 - esophageal carcinoma vs., 230 - esophageal perforation associated with, 214 - intramural benign esophageal tumors vs., 225 Esophageal inflammatory polyp, 227 Esophageal intramural pseudodiverticulosis, Candida esophagitis associated with, 163 Esophageal lymphoma, esophageal varices vs., 199–200 Esophageal mass - extrinsic, differential diagnosis, 157 - intraluminal, differential diagnosis, 157 Esophageal metastases and lymphoma, 232–233 - associated abnormalities, 233 - differential diagnosis, 233 - esophageal carcinoma vs., 229–230 - esophageal varices vs., 199–200 Esophageal motility disturbances, 184–187 - associated abnormalities, 186 - differential diagnosis, 158, 185 - genetics, 186 - image gallery, 184, 187 - intramural pseudodiverticulosis associated with, 207 Esophageal neoplasms, benign - extrinsic mass, differential diagnosis, 157 - fibrovascular polyp, 226 - inflammatory polyp, 227 - intraluminal mass, differential diagnosis, 157 - intramural benign esophageal tumors. See Intramural benign esophageal tumors. - intrinsic/extrinsic, esophageal achalasia associated with, 182 Esophageal neoplasms, malignant - carcinoma. See Esophageal carcinoma. - metastases and lymphoma. See Esophageal metastases and lymphoma. Esophageal papilloma, inflammatory polyp vs., 227 Esophageal perforation, 212–215 - differential diagnosis, 213 xvii

INDEX - image gallery, 212, 215 - pulsion diverticulum vs., 209 - traction diverticulum vs., 208 Esophageal rings - foreign body associated with, 211 - muscular or contractile or A ring, Schatzki ring vs., 193 Esophageal rupture or transection. See Esophageal perforation. Esophageal scleroderma, 188–191 - associated abnormalities, 190 - Barrett esophagus vs., 171 - Chagas disease of esophagus vs., 165 - differential diagnosis, 189 - esophageal achalasia vs., 181 - form of esophageal motility disturbances, imaging, 185 - genetics, 190 - image gallery, 188, 191 - reflux esophagitis vs., 167 - types, 189 Esophageal strictures - differential diagnosis, 157 - esophageal webs vs., 178 - intramural pseudodiverticulosis associated with, 207 - peptic, esophageal achalasia associated with, 182 Esophageal tumor, cricopharyngeal achalasia vs., 179 Esophageal tumor recurrence, radiation esophagitis vs., 175 Esophageal ulceration, differential diagnosis, 157 Esophageal varices, 198–201 - differential diagnosis, 199–200 - esophageal metastases and lymphoma vs., 233 - image gallery, 198, 201 - imaging, in portal hypertension, 115 - thrombosed, inflammatory polyp vs., 227 Esophageal venous drainage, normal: esophageal varices associated with, 200 Esophageal wall thinning, esophageal achalasia associated with, 182 Esophageal webs, 178 - differential diagnosis, 178 - eosinophilic gastroenteritis and esophagitis vs., 176 - foreign body associated with, 211 - intramural pseudodiverticulosis associated with, 207 - Schatzki ring vs., 193 - Zenker diverticulum vs., 204 Esophagectomy: Ivor Lewis and other procedures, 218–223 - image gallery, 218, 221–223 - imaging, 219–220 complications, 219–220 recommendations, 220 surgical procedure, 219 Esophagitis - Barrett esophagus vs., 171 - Candida esophagitis. See Candida esophagitis. - caustic. See Caustic esophagitis. - chronic, intramural pseudodiverticulosis associated with, 207 - cytomegalovirus, Candida esophagitis associated with, 163 xviii

- drug-induced. See Drug-induced esophagitis. - eosinophilic, 176 differential diagnosis, 176 esophageal webs associated with, 178 - foreign body vs., 211 - infectious, radiation esophagitis vs., 175 - intramural pseudodiverticulosis vs., 207 - nasogastric intubation, radiation esophagitis vs., 175 - radiation. See Radiation esophagitis. - reflux. See Reflux esophagitis. - viral. See Viral esophagitis. - without stricture, esophageal achalasia vs., 182 Esophagus, 156–233 - achalasia. See Esophageal achalasia. - anatomy (graphic images), 158–159 - Barrett esophagus, 170–171 differential diagnosis, 171 drug-induced esophagitis vs., 174 genomic instability, esophageal carcinoma associated with, 230 - Boerhaave syndrome, 216–217 differential diagnosis, 217 esophageal perforation vs., 213 - Candida esophagitis. See Candida esophagitis. - caustic esophagitis. See Caustic esophagitis. - Chagas disease, 165 differential diagnosis, 165 esophageal achalasia associated with, 182 - cricopharyngeal achalasia, 179 - differential diagnosis, 157 dilated esophagus, 157 esophageal dysmotility, 157 esophageal outpouching (diverticula), 157 esophageal strictures, 157 esophageal ulceration, 157 extrinsic mass, 157 intraluminal mass, 157 lesion at pharyngoesophageal junction, 157 odynophagia, 157 - diverticula. See Esophageal diverticula. - drug-induced esophagitis. See Drug-induced esophagitis. - eosinophilic esophagitis, 176 differential diagnosis, 176 esophageal webs associated with, 178 - epidermolysis and pemphigoid of esophagus, 177 esophageal webs associated with, 178 Zenker diverticulum vs., 204 - esophagectomy: Ivor Lewis and other procedures, 218–223 - esophagitis. See Esophagitis. - foreign body. See Esophageal foreign body. - hiatal hernia. See Hiatal hernia. - iatrogenic injury of, due to feeding tubes: caustic esophagitis vs., 173 - image gallery, 160–161 - imaging approach, 156–161 anatomy and terminology, 156 anatomy-based imaging issues, 156–157 differential diagnosis, 157 imaging protocols, 156

INDEX mural anatomy, 156 - imaging findings, in cystic fibrosis, 19 - intramural pseudodiverticulosis, 206–207 - motility disturbances, 184–187 differential diagnosis, 158, 185 intramural pseudodiverticulosis associated with, 207 - neoplasms benign. See Esophageal neoplasms, benign. malignant. See Esophageal carcinoma; Esophageal metastases and lymphoma. - neuromuscular disorders, esophageal achalasia vs., 182 - perforation. See Esophageal perforation. - postoperative state, esophageal achalasia vs., 182 - pulsion diverticulum. See Pulsion diverticulum. - radiation esophagitis. See Radiation esophagitis. - reflux esophagitis. See Reflux esophagitis. - Schatzki ring, 192–193 differential diagnosis, 193 esophageal webs vs., 178 - scleroderma. See Esophageal scleroderma. - superimposed infection, esophageal achalasia associated with, 182 - traction diverticulum, 208 differential diagnosis, 208 pulsion diverticulum vs., 209 - varices. See Esophageal varices. - viral esophagitis. See Viral esophagitis. - webs. See Esophageal webs. - Zenker diverticulum, 202–205 differential diagnosis, 203–204 traction diverticulum vs., 208 Eventration and paralysis of diaphragm, 152 - Bochdalek hernia vs., 112 - gastric volvulus associated with, 264 - traumatic diaphragmatic rupture vs., 121 Exophytic gastric carcinoma, gastric GIST vs., 295 External hernias. See Hernias, external. Extramedullary hematopoiesis, CT findings in sickle cell anemia, 23 Extrapancreatic fat necrosis, 991

F

Fallen or dependent viscus, in traumatic diaphragmatic rupture, 121 Familial adenomatous polyposis (FAP) - ampullary carcinoma associated with, 962 - colon carcinoma associated with, 526 - duodenal polyps associated with, 332 - familial polyposis and Gardner syndrome associated with, 536 - gallbladder polyps associated with, 953 - gastric polyps associated with, 288 - and related syndromes, hamartomatous polyposis syndrome vs., 437 Familial aggregation of pancreatic cancer, pancreatic ductal carcinoma associated with, 1036 Familial colon cancer, pancreatic ductal carcinoma associated with, 1036

Familial GIST syndrome, intestinal GIST associated with, 449 Familial polyposis and Gardner syndrome, 534–539 - associated abnormalities, 536 - associated with desmoid neoplasms, 138 - Brunner gland hyperplasia vs., 323 - colonic polyps associated with, 518 - differential diagnosis, 535–536 - duodenal carcinoma associated with, 335 - gallbladder carcinoma associated with, 958 - genetics, 536 - image gallery, 534, 537–539 - pancreatic ductal carcinoma associated with, 1036 Fascioliasis, pancreatobiliary. See Pancreatobiliary parasites. Fat-containing lesion of peritoneal cavity, differential diagnosis, 67 Fat deposited in liver, steatosis and steatohepatitis associated with, 634 Fatty infiltration, focal pancreatic: pancreatic lipomatous pseudohypertrophy vs., 1013 Fatty infiltration of pancreatic head, asymmetric: pancreatic ductal carcinoma vs., 1036 Fatty liver, focal sparing with - arterioportal shunt vs., 697 - transient hepatic attenuation or intensity difference vs., 691 Fatty liver of pregnancy, acute, HELLP syndrome vs., 733 Fatty lobulation, normal: cystic fibrosis vs., 20 Fatty lobulation of pancreas, asymmetric, 986–987 - differential diagnosis, 987 - staging, grading, & classification, 987 Fatty metamorphosis, hepatic. See Steatosis and steatohepatitis. Fatty replacement of pancreas, diffuse: asymmetric fatty lobulation of pancreas vs., 987 Fecal impaction and stercoral ulceration, 512 - colonic ileus and Ogilvie syndrome vs., 510 - differential diagnosis, 512 Fecal impaction, colonic diverticulitis associated with, 494 Fecal mass, villous adenoma vs., 522 Feeding tubes: iatrogenic injury, 268–269 Female genital tuberculosis, radiologic findings, 14 Femoral hernia, 96–97 - differential diagnosis, 97 - inguinal hernia vs., 94 - obturator hernia vs., 99 Femorocele. See Femoral hernia. Fibrolamellar carcinoma, 814–819 - differential diagnosis, 815 - focal nodular hyperplasia vs., 782 - hepatic adenoma vs., 787 - image gallery, 814, 817–819 - peripheral (intrahepatic) cholangiocarcinoma vs., 822 - staging, grading, & classification, 815 Fibrolytic anemia, HELLP syndrome associated with, 733 Fibromatosis, deep or aggressive. See Desmoid tumors. Fibrosing mediastinitis, superior vena cava obstruction associated with, 37 Fibrosing mesenteritis. See Sclerosing mesenteritis. xix

INDEX Fibrosis - congenital hepatic. See Congenital hepatic fibrosis. - cystic. See Cystic fibrosis. - focal confluent fibrosis. See Focal confluent fibrosis, hepatic. - mediastinal, autoimmune or postradiation: superior vena cava obstruction associated with, 37 - renal, Caroli disease associated with, 872 - retroperitoneal. See Retroperitoneal fibrosis. Fibrotic disorders, sclerosing mesenteritis associated with, 82 Fibrovascular polyp, esophageal, 226 Fibroxanthogranulomatous cholecystitis. See Xanthogranulomatous cholecystitis. Fistulas - aortoenteric, 328–329 - arteriovenous, traumatic intrahepatic: hereditary hemorrhagic telangiectasia vs., 727 - cholecysto-choledochal fistula, Mirizzi syndrome associated with, 920 - colocolic, 406 - colonic, differential diagnosis, 453 - colovaginal, 406 - colovesical fistula to thick-walled bladder, 406 - duodenal, 406 - enteric fistulas and sinus tracts, 404–411 - enterocolic, 406 - enterocutaneous abdominal incision and injection sites vs., 128 fluoroscopic findings, 406 - enteroenteric, 406 - intrahepatic arteriovenous fistula, traumatic: hereditary hemorrhagic telangiectasia vs., 727 - pancreatic, complication of pancreatic surgery, 1019 - perianal. See Perianal fistulas. - traumatic intrahepatic arteriovenous fistula, hereditary hemorrhagic telangiectasia vs., 727 Fistulas and sinus tracts, enteric, 404–411 Flow artifact, biliary, 863–864 Fluid collections - abdominal, congenital gallbladder abnormalities vs., 868 - complication of acute pancreatitis, 991 Fluid in gastrointestinal tract, biliary artifact, 864 Focal autoimmune pancreatitis, pancreatic ductal carcinoma vs., 1036 Focal confluent fibrosis, hepatic, 658–661 - arterioportal shunt vs., 697 - differential diagnosis, 659 - epithelioid hemangioendothelioma vs., 828 - image gallery, 658, 660–661 - peripheral (intrahepatic) cholangiocarcinoma vs., 822 - postoperative changes of liver vs., 746 - transient hepatic attenuation or intensity difference vs., 691 Focal fatty infiltration, pancreatic: pancreatic lipomatous pseudohypertrophy vs., 1013 Focal lipomatosis of focal fatty infiltration of pancreas. See Asymmetric fatty lobulation of pancreas. Focal liver lesion - hypervascular, differential diagnosis, 585 xx

- with hemorrhage, differential diagnosis, 585 Focal nodular hyperplasia, 780–785 - differential diagnosis, 781–782 - fibrolamellar carcinoma vs., 815 - hepatic adenoma vs., 787 - hepatic cavernous hemangioma associated with, 774 - image gallery, 780, 778–785 - multiple, nodular regenerative hyperplasia vs., 662 - peliosis hepatis vs., 722 Focal pancreatitis, asymmetric fatty lobulation of pancreas vs., 987 Focal sparing with fatty liver - arterioportal shunt vs., 697 - transient hepatic attenuation or intensity difference vs., 691 Focal steatosis - hepatic angiomyolipoma and lipoma vs., 799 - hepatic infarction vs., 719 - radiation-induced liver disease vs., 741 Foreign bodies, abdominal, 42–47 - image gallery, 42, 45–47 - imaging, 43–44 ingested foreign bodies, 43 inserted foreign bodies, 43–44 intentionally retained surgical items, 44 retained surgical items, 44 - small bowel diverticula vs., 351 Foreign body, esophageal, 210–211 - differential diagnosis, 211 - esophageal carcinoma vs., 230 - esophageal perforation associated with, 214 - intramural benign esophageal tumors vs., 225 Franz tumor. See Pancreatic solid and pseudopapillary neoplasm. Free fluid - intraperitoneal, after open laparotomy or laparoscopy, 125 - physiologic, ascites vs., 86 Frey procedure, 1019 Functional megacolon, sigmoid volvulus vs., 503 Fundic gland polyps, gastric polyps associated with, 288 Fundoplication complications, esophagus - esophageal motility disturbances vs., 185 - esophageal scleroderma vs., 189 Fundoplication complications, stomach, 274–279 - image gallery, 274, 277–279 - imaging, 275–287 Fungal infections - hepatic TB and fungal infections, 604–607 - infectious colitis associated with, 460 - microsporidia, intestinal, 361, 362 Fungal microabscesses, splenic infection and abscess associated with, 556

G

Gallbladder - agenesis congenital absence of hepatic segments associated with, 599

INDEX congenital gallbladder abnormalities associated with, 868 - chronic inflammation, gallbladder carcinoma associated with, 957 - congenital abnormalities, 866–869 - Courvoisier, gallbladder hydrops and empyema vs., 893 - CT findings metastatic melanoma, 59 sickle cell anemia, 23 - diffuse gallbladder wall thickening, differential diagnosis, 855 - distended, differential diagnosis, 855 - gas in bile ducts or gallbladder, differential diagnosis, 855 - Hartmann pouch, congenital gallbladder abnormalities vs., 868 - hemorrhage, milk of calcium bile vs., 929 - high attenuation (hyperdense) bile in, differential diagnosis, 855 - iatrogenic high-density material in, porcelain gallbladder vs., 927 - infection, chronic: gallbladder carcinoma associated with, 957 - intraluminal polyp, gallstones and sludge vs., 897 - ischemia, acalculous cholecystitis associated with, 908 - malformation. See Congenital gallbladder abnormalities. - metastatic disease to, gallbladder carcinoma vs., 957 - obstruction, intermittent: porcelain gallbladder associated with, 927 - porcelain. See Porcelain gallbladder. - ultrasonographic findings HIV/AIDS, 10 metastatic melanoma, 59 Gallbladder adenomyomatosis - gallbladder carcinoma vs., 957 - gallbladder polyps vs., 953 - gallstones and sludge vs., 897 - hyperplastic cholecystoses associated with, 924 - xanthogranulomatous cholecystitis vs., 911 Gallbladder carcinoma, 956–959 - acalculous cholecystitis vs., 908 - associated abnormalities, 958 - differential diagnosis, 957 - gallstones and sludge vs., 897–898 - genetics, 958 - hyperplastic cholecystoses vs., 924 - image gallery, 956, 959 - Mirizzi syndrome vs., 919 - polypoid, gallbladder polyps vs., 953 - porcelain gallbladder associated with, 927 - staging, grading, & classification, 958 - xanthogranulomatous cholecystitis vs., 911 Gallbladder fossa, metastatic disease to: gallbladder carcinoma vs., 957 Gallbladder hydrops and empyema, 892–895 Gallbladder metastases and lymphoma, gallbladder polyps vs., 953 Gallbladder outlet obstruction, chronic: gallbladder hydrops and empyema associated with, 894

Gallbladder polyps, 952–955 - differential diagnosis, 953 - gallbladder carcinoma vs., 957 - genetics, 953 - image gallery, 952, 955 - staging, grading, & classification, 953–954 Gallbladder wall - dystrophic mural calcification, porcelain gallbladder associated with, 927 - edema, acalculous cholecystitis vs., 907–908 Gallbladder wall thickening - diffuse, differential diagnosis, 855 - focal, differential diagnosis, 855 - nonspecific, acute calculous cholecystitis vs., 904 Gallstone ileus, 403 Gallstones - acute pancreatitis and complications associated with, 992 - chronic pancreatitis associated with, 1002 - Crohn disease associated with, 372 - dropped, gallstone ileus vs., 403 - emphysematous cholecystitis vs., 916 - gallbladder polyps vs., 953 - hyperplastic cholecystoses associated with, 924 - intraductal mimics, artifact, 864 - large or filling gallbladder, porcelain gallbladder vs., 927 - milk of calcium bile associated with, 929 - porcelain gallbladder associated with, 927 - vicarious excretion of contrast medium vs., 153 - xanthogranulomatous cholecystitis associated with, 911 Gallstones and sludge, 896–901 - differential diagnosis, 897–898 - etiology cholesterol stones, 898 pigment stones, 898 sludge, 898 - image gallery, 896, 899–901 - milk of calcium bile vs., 929 - tumefactive sludge, gallbladder polyps vs., 953 - vicarious excretion of contrast medium vs., 153 Ganglion cell reduction or damage, colonic ileus and Ogilvie syndrome associated with, 510 Gangrenous cholecystitis - emphysematous cholecystitis vs., 915 - gallbladder hydrops and empyema vs., 893 - xanthogranulomatous cholecystitis vs., 911 Gardner syndrome. See Familial polyposis and Gardner syndrome. Gas-forming cholangitis, emphysematous cholecystitis vs., 915 Gas-forming hepatic abscess, emphysematous cholecystitis vs., 915 Gas in biliary tree, from biliary-enteric anastomosis or post sphincterotomy: emphysematous cholecystitis vs., 915 Gastrectomy - gastric bezoar associated with, 261 - partial. See Partial gastrectomy: Bilroth procedures. Gastric antral narrowing, differential diagnosis, 237 Gastric bezoar, 260–261 - associated abnormalities, 261 xxi

INDEX - complication of partial gastrectomy, 271 - differential diagnosis, 261 Gastric carcinoids, 439 Gastric carcinoma, 298–303 - caustic gastroduodenal injury vs., 258 - differential diagnosis, 299–300 - ectopic pancreatic tissue vs., 989 - esophageal achalasia vs., 181 - exophytic, gastric GIST vs., 295 - extragastric primary carcinoma in, gastric metastases associated with, 306 - gastric bezoar vs., 261 - gastric metastases and lymphoma vs., 305 - gastric polyps vs., 287 - gastritis vs., 243 - image gallery, 298, 301–303 - intramural benign gastric tumors vs., 291 - Ménétrier disease vs., 257 - portal hypertension and varices vs., 116 - recurrence, after partial gastrectomy, 271 - staging, grading, & classification, 300 - Zollinger-Ellison syndrome vs., 253 Gastric dilation or outlet obstruction, differential diagnosis, 237–238 Gastric diverticulum, 242–243 - anatomical considerations, 236 - differential diagnosis, 243 Gastric folds, thickened: differential diagnosis, 237 Gastric fundal carcinoma, esophageal motility disturbances vs., 185 Gastric GIST, 294–297 - associated abnormalities, 296 - differential diagnosis, 295 - ectopic pancreatic tissue vs., 989 - gastric carcinoma vs., 300 - gastric metastases and lymphoma vs., 305 - gastric polyps vs., 288 - gastric ulcer vs., 249 - genetics, 295–296 - image gallery, 294, 297 - intramural benign gastric tumors associated with, 291 - staging, grading, & classification, 296 Gastric hypervascular submucosal lesions, other: ectopic pancreatic tissue vs., 989 Gastric lymphoma, gastric GIST vs., 295 Gastric metastases and lymphoma, 301–307 - associated abnormalities, 306 - caustic gastroduodenal injury vs., 258 - differential diagnosis, 305 - ectopic pancreatic tissue vs., 989 - gastric carcinoma vs., 300 - gastric polyps vs., 287–287 - gastric ulcer vs., 249–250 - gastritis vs., 244 - image gallery, 301, 307 - intramural benign gastric tumors vs., 291 - Ménétrier disease vs., 257 - staging, grading, & classification, 306 - Zollinger-Ellison syndrome vs., 253–254 Gastric neoplasms, benign - gastric polyps, 286–289 xxii

- intramural benign gastric tumors, 290–293 - "target" or bull's eye-lesions, differential diagnosis, 237 Gastric neoplasms, malignant - "drop" metastases from, colon carcinoma vs., 525 - gastric carcinoma. See Gastric carcinoma. - gastric GIST. See Gastric GIST. - gastric metastases and lymphoma. See Gastric metastases and lymphoma. Gastric outlet obstruction - differential diagnosis, 237–238 - gastroparesis vs., 259 Gastric polyps, 286–289 - differential diagnosis, 287–288 - image gallery, 286, 289 Gastric pseudolymphoma, gastric metastases and lymphoma vs., 305 Gastric stasis, complication of partial gastrectomy, 271 Gastric surgery, previous: gastric bezoar associated with, 261 Gastric thermal injury, caustic gastroduodenal injury vs., 258 Gastric tumors, intramural benign. See Intramural benign gastric tumors. Gastric ulcer, 248–251 - benign, gastric carcinoma vs., 299 - differential diagnosis, 249–250 - ectopic pancreatic tissue vs., 989 - genetics, 250 - image gallery, 248, 251 - intramural benign gastric tumors vs., 291 - perforated, barotrauma vs., 49 Gastric ulceration (without mass), differential diagnosis, 237 Gastric venous collateral vessel varices, left: imaging in portal hypertension, 115 Gastric volvulus, 262–267 - associated abnormalities, 264 - differential diagnosis, 263 - image gallery, 262, 265–267 Gastric wall, normal variant: gastric carcinoma vs., 299 Gastrict mass - intramural mass, differential diagnosis, 237 - mass lesions, differential diagnosis, 237 Gastrinoma, Zollinger-Ellison syndrome associated with, 251 Gastritis, 244–247 - AIDS-related, 245 - antral, 245 - associated abnormalities, 246 - atrophic chronic, gastric polyps associated with, 288 gastric carcinoma associated with, 300 imaging findings, 245 - caustic gastric carcinoma vs., 300 imaging findings, 245 - chronic remnant, complication of partial gastrectomy, 272 - classification, 245 - differential diagnosis, 245–246

INDEX - duodenitis associated with, 317 - emphysematous, 245 - eosinophilic imaging findings, 245 Zollinger-Ellison syndrome vs., 251 - erosive, gastric metastases and lymphoma vs., 305 - gastric carcinoma vs., 299 - gastric ulcer vs., 249 - granulomatous, 245 - Helicobacter pylori gastritis, gastric polyps associated with, 288 - hypertrophic, 245 - image gallery, 244, 247 - Ménétrier disease vs., 257 - radiation, 245 - tuberculous, 245 - upper GI imaging findings, 245 - Zollinger-Ellison syndrome vs., 253 Gastroduodenal injuries, caustic esophagitis associated with, 173 Gastroduodenal trauma, 326–327 - associated abnormalities, 327 - differential diagnosis, 327 - duodenal carcinoma vs., 335 - staging, grading, & classification, 327 Gastroesophageal reflux - Barrett esophagus associated with, 171 - chronic, esophageal webs associated with, 178 - esophageal inflammatory polyp associated with, 227 - intramural pseudodiverticulosis associated with, 207 - reflux esophagitis associated with, 167–168 - Schatzki ring associated with, 193 - Zenker diverticulum associated with, 204 Gastrointestinal bleeding - occult, differential diagnosis, 344 - other causes, portal hypertension and varices vs., 116 Gastrointestinal duplication cyst - lymphangioma (mesenteric cyst), 133 - small intestine duplication cyst vs., 350 Gastrointestinal lymphoma, opportunistic intestinal infections vs., 361 Gastrointestinal stromal tumor (GIST) - colonic metastases and lymphoma vs., 541 - duodenal, duodenal metastases and lymphoma vs., 339 - familial GIST syndrome, intestinal GIST associated with, 449 - gastric. See Gastric GIST. - intestinal. See Intestinal GIST. - malignant, duodenal carcinoma vs., 335 - pancreatic ductal carcinoma vs., 1036 - peripancreatic, pancreatic neuroendocrine tumors vs., 1056 Gastrointestinal tract - CT findings amyloidosis, 27 leukemia and lymphoma, 55 metastatic melanoma, 59 mucosa-associated lymphoid tissue (MALT) lymphoma, 55 post-transplant lymphoproliferative disorder, 51 sarcoidosis, 29

- fluoroscopic findings, metastatic melanoma, 59 - metastatic tumors, metastatic melanoma vs., 60 Gastrointestinal tuberculosis, radiologic findings, 13 Gastrojejunostomy leaks, complication of pancreatic surgery, 1019 Gastroparesis, 259 Gastroschisis, malrotation of small intestine associated with, 349 Genitourinary tract, CT findings - amyloidosis, 27 - sarcoidosis, 29 Giant cell carcinoma, pancreatic, 1069. See also Atypical and rare pancreatic tumors. Giant sigmoid diverticulum, colonic diverticulosis vs., 489 Giardia infections (giardiasis) - intestinal, 361 - intestinal parasites and infestation associated with, 359 Gluten-sensitive enteropathy. See Celiac-sprue disease. Glycogen storage disease, 678–679 - associated abnormalities, 679 - differential diagnosis, 679 - genetics, 679 - hemochromatosis vs., 681 - hepatomegaly associated with, 689 - staging, grading, & classification, 679 - von Gierke type 1, hepatic adenoma associated with, 787 Glycogenic acanthosis, Candida esophagitis vs., 163 Gossypiboma, 44 Graft vs. host disease - complication of small intestine transplantation, 432 - esophageal webs associated with, 178 - venoocclusive disease vs., 717 Granulomatous colitis (Crohn disease) - infectious colitis vs., 459 - ischemic colitis vs., 476 - ulcerative colitis vs., 467 Granulomatous disease, primary splenic tumors vs., 576 Granulomatous gastritis, 245 Groin hernia. See Inguinal hernia. Groove pancreatitis, 1004–1007 - differential diagnosis, 1004 - image gallery, 1004, 1006–1007 - pancreatic ductal carcinoma vs., 1036 Growth factor receptor activity, gastric GIST associated with, 296 Gynecologic disorders, appendicitis vs., 480

H

Hamartoma - biliary. See Biliary hamartoma. - Brunner gland hamartoma. See Brunner gland hyperplasia. - duodenal, duodenal polyps vs., 332 - pancreatic, of duodenal wall. See Groove pancreatitis. - splenic CT findings, 575 key concepts, 575 MR findings, 575 xxiii

INDEX ultrasonographic findings, 575 Hamartomatous polyposis syndrome, 436–437. See also Peutz-Jeghers syndrome. - Brunner gland hyperplasia vs., 323 - colonic polyps associated with, 518 - differential diagnosis, 437 - gastric polyps associated with, 288 - genetics, 437 - staging, grading, & classification, 437 Hamartomatous polyps - colonic, 518 - duodenal, 331 Hamoudi tumor. See Pancreatic solid and pseudopapillary neoplasm. Hartmann pouch of gallbladder - compression or erosion into bile duct, Mirizzi syndrome associated with, 920 - congenital gallbladder abnormalities vs., 868 Heart disease, nodular regenerative hyperplasia associated with, 664 Heart, progressive injury: hemochromatosis associated with, 681 Helicobacter pylori gastritis, gastric polyps associated with, 288 Helicobacter pylori infection - duodenal ulcer associated with, 320 - duodenitis associated with, 317 - gastric carcinoma associated with, 300 - gastric ulcer associated with, 250 - gastritis associated with, 245 - leukemia and lymphoma associated with, 56 HELLP syndrome, 732–735 - associated abnormalities, 733–734 - differential diagnosis, 733 - hepatic infarction associated with, 719 - hepatic trauma vs., 737 - image gallery, 732, 735 - staging, grading, & classification, 734 Hemangioendothelial sarcoma. See Hepatic angiosarcoma. Hemangioendothelioma, epithelioid. See Epithelioid hemangioendothelioma. Hemangioma - hepatic cavernous. See Hepatic cavernous hemangioma. - hepatic, multiple: hepatic metastases and lymphoma vs., 846 - type of intramural benign gastric tumor, 292 Hemangioma, splenic - CT findings, 575 - key concepts, 575 - MR findings, 576 - splenic cyst vs., 573 - ultrasonographic findings, 576 Hemangiosarcoma. See Hepatic angiosarcoma. Hematologic disorders - splenic infarction associated with, 564 - splenomegaly and hypersplenism associated with, 559, 560 Hematoma - abdominal, abdominal abscess vs., 74 - biloma vs., 939 xxiv

duodenal, duodenal ulcer vs., 320 hepatic, biloma vs., 939 intramural benign gastric tumors vs., 291 intramural, intramural (mesenchymal) intestinal tumors vs., 434 - splenic, primary splenic tumors vs., 576 Hemidiaphragm, absence or hypoplasia: congenital absence of hepatic segments associated with, 599 Hemidiaphragm, elevated or deformed: differential diagnosis, 68 Hemobilia, vicarious excretion of contrast medium vs., 153 Hemochromatosis, 680–683 - associated abnormalities, 681 - differential diagnosis, 681 - glycogen storage disease vs., 679 - hepatomegaly associated with, 689 - image gallery, 680, 682–683 Hemoglobinopathies, splenic infection and abscess associated with, 556 Hemolysis, elevated liver enzymes, low platelets (HELLP). See HELLP syndrome. Hemolytic anemia, hepatomegaly associated with, 689 Hemoperitoneum - ascites vs., 86 - differential diagnosis, 68 - peritonitis vs., 78 - vicarious excretion of contrast medium vs., 153 Hemorrhage - complication of pancreatic surgery, 1019 - intestinal metastases and lymphoma vs., 445 - retroperitoneal, ileus associated with, 387 - spontaneous HELLP syndrome vs., 733 hepatic trauma vs., 737 Hemorrhagic or infected cyst, hepatic hydatid cyst vs., 613 Hemorrhagic telangiectasia, hereditary, 726–731 Henoch-Schönlein purpura. See also Vasculitis. - definition, 39 - imaging findings, 39 Hepatic abscess - amebic. See Hepatic amebic abscess. - arterioportal shunt associated with, 697 - ascending cholangitis associated with, 883–884 - biloma vs., 939 - gas-forming, emphysematous cholecystitis vs., 915 - hepatic infarction vs., 719 - hepatomegaly associated with, 689 - multiple, hepatic metastases and lymphoma vs., 846 - pancreatic, complication of pancreatic surgery, 1019 - pyogenic. See Hepatic pyogenic abscess. - splenic. See Splenic infection and abscess. - with septic thrombophlebitis, portal vein occlusion associated with, 702 Hepatic adenoma, 786–793 - differential diagnosis, 787 - focal nodular hyperplasia associated with, 782 - focal nodular hyperplasia vs., 781 - HELLP syndrome vs., 733 - hepatic angiomyolipoma and lipoma vs., 799 - image gallery, 786, 789–793 - peliosis hepatis vs., 722 -

INDEX - staging, grading, & classification, 787–788 Hepatic amebic abscess, 608–611 - associated abnormalities, 609 - differential diagnosis, 609 - hepatic pyogenic abscess vs., 601 - image gallery, 608, 610–611 Hepatic angiomyolipoma and lipoma, 798–801 - associated abnormalities, 799 - differential diagnosis, 799 - image gallery, 798, 800–801 - postoperative changes of liver vs., 746 Hepatic angiosarcoma, 838–841 - associated abnormalities, 839 - differential diagnosis, 839 - hepatic cavernous hemangioma vs., 774 - image gallery, 838, 840–841 - undifferentiated sarcoma vs., 843 Hepatic artery thrombosis, ischemic bile duct injury associated with, 944 Hepatic attenuation or intensity difference, transient. See Transient hepatic attenuation or intensity difference (THADs and THIDs). Hepatic cavernous hemangioma, 772–779 - arterioportal shunt vs., 697 - associated abnormalities, 774 - differential diagnosis, 774 - fibrolamellar carcinoma vs., 815 - focal confluent fibrosis vs., 659 - focal nodular hyperplasia vs., 782 - hepatic angiosarcoma vs., 839 - hepatic cyst vs., 766 - image gallery, 772, 775–779 - peliosis hepatis vs., 722 - transient hepatic attenuation or intensity difference vs., 691 Hepatic cirrhosis. See Cirrhosis. Hepatic congestion, passive. See Passive hepatic congestion. Hepatic cyst, 764–771 - AD polycystic liver disease vs., 595 - associated abnormalities, 766 - biloma vs., 939 - Caroli disease associated with, 872 - choledochal cyst vs., 876 - differential diagnosis, 765–766 - hemorrhagic or infected, biliary cystadenocarcinoma vs., 833 - image gallery, 764, 767–771 - multiple, hepatic metastases and lymphoma vs., 846 - multiple simple, biliary hamartoma vs., 795 - simple biloma vs., 939 choledochal cyst vs., 876 Hepatic epithelioid hemangioendothelioma, focal confluent fibrosis vs., 659 Hepatic fatty metamorphosis. See Steatosis and steatohepatitis. Hepatic fibrosis, congenital. See Congenital hepatic fibrosis.

Hepatic flexure diverticulitis, acute calculous cholecystitis vs., 904 Hepatic foregut cyst, ciliated, hepatic cyst vs., 766 Hepatic hematoma, biloma vs., 939 Hepatic hydatid cyst, 612–615 - biliary cystadenocarcinoma vs., 834 - differential diagnosis, 613 - hepatic amebic abscess vs., 609 - hepatic cyst vs., 766 - hepatic pyogenic abscess vs., 601 - image gallery, 612, 614–615 - undifferentiated sarcoma vs., 843 Hepatic infarction, 718–721 - complication of pancreatic surgery, 1019 - differential diagnosis, 719 - image gallery, 718, 721 - infected tissue, hepatic pyogenic abscess associated with, 601 - radiation-induced liver disease vs., 741 Hepatic infection - arterioportal shunt associated with, 697 - hepatic infarction associated with, 719 - opportunistic biliary hamartoma vs., 795 sarcoidosis vs., 29 steatosis and steatohepatitis vs., 634 - TB and fungal infections, 604–607 associated abnormalities, 605 differential diagnosis, 605 image gallery, 604, 606–607 Hepatic inflammatory pseudotumor, 802–805 Hepatic injury from toxins, 638–641 - differential diagnosis, 639 - image gallery, 638, 640–641 - staging, grading, & classification, 639 - viral hepatitis vs., 621 Hepatic laceration, arterioportal shunt associated with, 697 Hepatic lesions - macronodular, tuberculosis vs., 14 - miliary, tuberculosis vs., 14 Hepatic lipoma. See Hepatic angiomyolipoma and lipoma. Hepatic mass, cystic: differential diagnosis, 585 Hepatic metastases and lymphoma, 844–851 - angiosarcoma vs., 839 - arteriovenous shunting within tumors, hereditary hemorrhagic telangiectasia vs., 727 - cystic or necrotic, hepatic cyst vs., 765 - differential diagnosis, 846 - hypervascular focal nodular hyperplasia vs., 782 hepatic adenoma vs., 787 hepatic cavernous hemangioma vs., 774 hepatocellular carcinoma vs., 808 peliosis hepatis vs., 722 - image gallery, 844, 847–851 - inflammatory pseudotumor vs., 804 - multiple/solitary small metastatic lesions, biliary hamartoma vs., 795 - peripheral (intrahepatic) cholangiocarcinoma vs., 882–822 xxv

INDEX primary biliary cirrhosis vs., 653 pyogenic abscess vs., 601 rim-enhancing, postoperative pancreas vs., 1020 solitary necrotic nodule vs., 676 staging, grading, & classification, 846 steatosis and steatohepatitis vs., 634 transient hepatic attenuation or intensity difference associated with, 692 - treated cirrhosis vs., 644 epithelioid hemangioendothelioma vs., 827 - tuberculosis and fungal infections vs., 605 - undifferentiated sarcoma vs., 843 Hepatic neoplasms - arterioportal shunt associated with, 697 - arteriovenous shunting within tumors, hereditary hemorrhagic telangiectasia vs., 727 - HELLP syndrome vs., 733 - mass cystic, differential diagnosis, 585 fat-containing, differential diagnosis, 585 with capsular retraction, differential diagnosis, 585 with central or eccentric scar, differential diagnosis, 585 - primary, transient hepatic attenuation or intensity difference associated with, 692 - treated, focal confluent fibrosis vs., 659 Hepatic neoplasms, benign - adenoma. See Hepatic adenoma. - angiomyolipoma and lipoma, 798–801 differential diagnosis, 799 postoperative changes of liver vs., 746 - biliary hamartoma. See Biliary hamartoma. - cavernous hemangioma. See Hepatic cavernous hemangioma. - cyst. See Hepatic cyst. - focal nodular hyperplasia. See Focal nodular hyperplasia. - inflammatory pseudotumor, 802–805 - portal hypertension and varices associated with, 116 Hepatic neoplasms, malignant - angiosarcoma. See Hepatic angiosarcoma. - biliary cystadenocarcinoma. See Biliary cystadenocarcinoma. - epithelioid hemangioendothelioma, 826–831 differential diagnosis, 827–828 focal confluent fibrosis vs., 659 - fibrolamellar carcinoma. See Fibrolamellar carcinoma. - hepatocellular carcinoma. See Hepatocellular carcinoma. - metastases and lymphoma. See Hepatic metastases and lymphoma. - peripheral (intrahepatic) cholangiocarcinoma. See Peripheral (intrahepatic) cholangiocarcinoma. - undifferentiated sarcoma, 842–843 Hepatic opportunistic infection - biliary hamartoma vs., 795 - post-transplant lymphoproliferative disorder vs., 52 - sarcoidosis vs., 29 - steatosis and steatohepatitis vs., 634 -

xxvi

Hepatic pyogenic abscess, 600–603 - biliary cystadenocarcinoma vs., 834 - biliary IPMN vs., 967 - differential diagnosis, 601 - hepatic amebic abscess vs., 609 - hepatic cyst vs., 766 - hepatic hydatid cyst vs., 613 - image gallery, 600, 602–603 - peliosis hepatis vs., 722–723 - postoperative changes of liver vs., 745 Hepatic sarcoidosis, cirrhosis vs., 644 Hepatic schistosomiasis, 616–619 Hepatic segments, congenital absence of, 598–599 - associated abnormalities, 599 - differential diagnosis, 599 - postoperative changes of liver vs., 746 Hepatic sinusoidal obstruction syndrome. See Venoocclusive disease, hepatic. Hepatic steatosis. See Steatosis and steatohepatitis. Hepatic transplantation, 754–763 - hepatic infarction associated with, 719 - image gallery, 754, 757–763 - imaging, 755–756 allograft rejection, 755 biliary complications, 755 extrahepatic complications, 756 normal post-transplantation findings, 755 pre-transplantation evaluation, 755 recurrent disease within allograft, 756 vascular complications, 755–756 Hepatic trauma, 736–739 - associated abnormalities, 738 - differential diagnosis, 737 - HELLP syndrome vs., 733 - hepatic infarction vs., 719 - image gallery, 736, 739 - pancreatic trauma associated with, 1016 - staging, grading, & classification, 738 Hepatic tuberculosis (TB) and fungal infections, 604–607 Hepatic tumor, bleeding: hepatic trauma vs., 737 Hepatic vein obstruction, Budd-Chiari syndrome associated with, 712 Hepatic venoocclusive disease, 716–717 - differential diagnosis, 717 - portal hypertension and varices associated with, 116 - transjugular intrahepatic portosystemic shunt vs., 750 Hepatic venous outflow obstruction. See Budd-Chiari syndrome. Hepaticojejunostomy leaks, complication of pancreatic surgery, 1019 Hepatitis - alcoholic autoimmune hepatitis vs., 631 hepatic injury from toxins vs., 639 - ascites associated with, 86 - autoimmune. See Autoimmune hepatitis. - severe, steatosis and steatohepatitis associated with, 634 - steatosis and steatohepatitis vs., 634 - viral. See Viral hepatitis. - Wilson disease vs., 685

INDEX Hepatitis A, viral hepatitis associated with, 622 Hepatitis B, viral hepatitis associated with, 622 Hepatitis C - cirrhosis associated with, 644 - viral hepatitis associated with, 622 Hepatobiliary cystadenoma. See Biliary cystadenocarcinoma. Hepatobiliary surgery, hepatic infarction associated with, 719 Hepatocellular adenoma. See Hepatic adenoma. Hepatocellular carcinoma, 806–813 - arteriovenous shunting within tumors, hereditary hemorrhagic telangiectasia vs., 727 - biliary papillomatosis vs., 965 - differential diagnosis, 808 - fibrolamellar. See Fibrolamellar carcinoma. - fibrolamellar carcinoma vs., 815 - genetics, 808 - HELLP syndrome vs., 733 - hemochromatosis associated with, 681 - hepatic adenoma vs., 787 - hepatic angiomyolipoma and lipoma vs., 799 - hepatic angiosarcoma vs., 839 - hepatomegaly associated with, 689 - image gallery, 806, 810–813 - multifocal hepatic metastases and lymphoma vs., 846 nodular regenerative hyperplasia vs., 662 - peripheral (intrahepatic) cholangiocarcinoma vs., 822 - portal vein occlusion associated with, 702 - regenerative and dysplastic nodules vs., 669 - treated, epithelioid hemangioendothelioma vs., 827 Hepatocyte destruction, HELLP syndrome associated with, 733 Hepatolenticular degeneration. See Wilson disease. Hepatolithiasis, biliary IPMN associated with, 968 Hepatoma. See Hepatocellular carcinoma. Hepatomegaly, 688–689 Hepatosplenic tuberculosis, radiologic findings, 13 Hepatosplenomegaly, CT findings in amyloidosis, 27 Hepatotoxins, steatosis and steatohepatitis associated with, 634 Hereditary angioedema, intestinal (angioneurotic) angioedema associated with, 381 Hereditary breast and ovarian cancer syndrome, pancreatic ductal carcinoma associated with, 1036 Hereditary hemorrhagic telangiectasia, 726–731 - associated abnormalities, 728 - differential diagnosis, 727–728 - genetics, 728 - image gallery, 726, 729 Hereditary nonpolyposis colorectal cancer - ampullary carcinoma associated with, 962 - colon carcinoma associated with, 526 - colonic polyps associated with, 518 - small bowel carcinoma associated with, 443 Hereditary pancreatitis - chronic pancreatitis associated with, 1002 - pancreatic ductal carcinoma associated with, 1036

Hernias, external, 92–103 - abdominal wall defect, differential diagnosis, 68 - femoral hernia, 96–97 differential diagnosis, 97 inguinal hernia vs., 94 obturator hernia vs., 99 - inguinal hernia, 92–95 differential diagnosis, 94 femoral hernia vs., 97 obturator hernia vs., 99 - lumbar hernia, 102 - nontraumatic, traumatic abdominal wall hernia vs., 119 - obturator hernia, 98–99 differential diagnosis, 99 femoral hernia vs., 97 - perineal, obturator hernia vs., 99 - sciatic hernia, obturator hernia vs., 99 - spigelian hernia, 101 differential diagnosis, 101 umbilical hernia vs., 103 - through laparoscopy port, spigelian hernia vs., 101 - traumatic abdominal wall hernia, 118–119 - umbilical hernia, 103 differential diagnosis, 103 spigelian hernia vs., 101 - ventral hernia, 100 spigelian hernia vs., 101 umbilical hernia vs., 103 Hernias, internal, 104–113 - Bochdalek hernia, 112 differential diagnosis, 112 gastric volvulus associated with, 264 traumatic diaphragmatic rupture vs., 121 - colonic transverse loop, gastric volvulus associated with, 264 - diaphragmatic malrotation of small intestine associated with, 349 post-esophagectomy, 220 - hiatal. See Hiatal hernia. - incarcerated, omental infarct associated with, 90 - Morgagni hernia, 113 differential diagnosis, 113 gastric volvulus associated with, 264 traumatic diaphragmatic rupture vs., 121 - paraduodenal hernia. See Paraduodenal hernia. - paraesophageal, gastric volvulus associated with, 264 - pericecal paraduodenal hernia vs., 106 with obstruction, transmesenteric postoperative hernia vs., 110 - small bowel obstruction associated with, 390 - transmesenteric postoperative hernia, 108–111 differential diagnosis, 109 paraduodenal hernia vs., 105 Herpesvirus infection, Candida esophagitis associated with, 163 Heterotaxy syndrome, asplenia and polysplenia associated with, 551 HHT1 and HHT2 gene mutation, hereditary hemorrhagic telangiectasia associated with, 728 xxvii

INDEX HHV8 (human herpesvirus type 8), Kaposi sarcoma associated with, 63 Hiatal hernia, 194–197 - differential diagnosis, 195 - gastric volvulus vs., 263 - image gallery, 194, 197 - pulsion diverticulum vs., 209 - Schatzki ring associated with, 193 - Zenker diverticulum associated with, 204 High fat diet, pancreatic ductal carcinoma associated with, 1036 Hirschsprung disease, colonic ileus and Ogilvie syndrome vs., 509 Histoplasmosis, infectious lymphadenopathy from: superior vena cava obstruction associated with, 37 HIV/AIDS, 8–11 - CT findings, 9 - differential diagnosis, 11 - hepatic TB and fungal infections associated with, 605 - image gallery, 8, 11 - pathology, 11 Kaposi sarcoma, 11 non-Hodgkin lymphoma, 11 - ultrasonographic findings, 9–10 HLA-B5, ulcerative colitis associated with, 468 HLA-BW52, ulcerative colitis associated with, 468 HLA-DQw2, celiac disease associated with, 366 HLA-DR1, 4, and 5 - esophageal motility disturbances associated with, 186 - esophageal scleroderma associated with, 190 - intestinal scleroderma associated with, 378 HLA-DR2, ulcerative colitis associated with, 468 HLA-DR3, celiac disease associated with, 366 HLA-DR5, intestinal scleroderma associated with, 378 HLA-DRB11, 12, 14, 15, and 17, sarcoidosis associated with, 30 Hodgkin lymphoma. See Lymphoma. Hormonal disorders, Crohn disease associated with, 372 Human herpesvirus type 8 (HHV8), Kaposi sarcoma associated with, 63 Human immunodeficiency virus (HIV). See HIV/AIDS. Hydatid cyst. See Hepatic hydatid cyst. Hydrochloric acid, caustic esophagitis associated with, 173 Hydrops of gallbladder. See Gallbladder hydrops and empyema. Hydrosalpinx, peritoneal inclusion cyst vs., 131 Hypercoagulable states - hepatic infarction associated with, 719 - ischemic enteritis associated with, 413 - transient hepatic attenuation or intensity difference associated with, 692 Hyperlipidemia - chronic pancreatitis associated with, 1002 - steatosis and steatohepatitis associated with, 634 Hyperparathyroidism - duodenal ulcer associated with, 320 - gastric ulcer associated with, 250 Hyperperfusion syndrome. See Systemic hypotension.

xxviii

Hyperplasia - Brunner gland, 322–323 differential diagnosis, 323 duodenal polyps vs., 331 hamartomatous polyposis syndrome vs., 437 - focal nodular. See Focal nodular hyperplasia. - lymphoid, familial polyposis and Gardner syndrome vs., 535 - nodular regenerative. See Nodular regenerative hyperplasia. Hyperplastic cholecystoses, 922–925 - acalculous cholecystitis vs., 908 - associated abnormalities, 924 - congenital gallbladder abnormalities vs., 868 - differential diagnosis, 924 - image gallery, 922, 925 Hyperplastic gastropathy. See Ménétrier disease. Hyperplastic polyps - colonic, 518 - duodenal, 331 Hypersplenism. See Splenomegaly and hypersplenism. Hypertrophic gastritis, 245 Hypervascular liver mass - arterioportal shunt vs., 697 - transient hepatic attenuation or intensity difference vs., 691 Hypervascular lymphadenopathy, Kaposi sarcoma vs., 63 Hypervascular metastases, peliosis hepatis vs., 722 Hypoplasia of hepatic lobes or segments. See Congenital absence of hepatic segments. Hypoproteinemia, Ménétrier disease associated with, 257 Hyposplenism, celiac-sprue disease associated with, 366 Hypotension, systemic, 34–35 - differential diagnosis, 35 - ischemic enteritis associated with, 413 Hypotensive episodes, ischemic colitis associated with, 476 Hypovolemic shock complex. See Systemic hypotension.

I

Iatrogenic causes, hepatic infarction associated with, 719 Iatrogenic injury: feeding tubes, 268–269 - caustic esophagitis vs., 173 - imaging, 269 IgA deficiency, celiac-sprue disease vs., 366 IgG4 pancreatitis. See Autoimmune (IgG4) pancreatitis. IgG4-related inflammatory and fibrotic disorders, sclerosing mesenteritis associated with, 82 IgG4-related sclerosing cholangitis. See Autoimmune (IgG4) cholangitis. Ileitis - infectious, Crohn disease vs., 372 - mesenteric adenitis and enteritis associated with, 357 Ileocecal area, mass or inflammation of: differential diagnosis, 453 Ileocecal lesions, tuberculosis vs., 14 Ileocecal syndrome. See Neutropenic colitis (typhlitis). Ileocecal valve lipoma and lipomatous infiltration, 435

INDEX Ileocolic tuberculosis, colonic metastases and lymphoma vs., 541 Ileocolitis. See Crohn disease. Ileum, terminal, stenosis of: differential diagnosis, 343 Ileus, 386–387 - acute cecal volvulus vs., 507 sigmoid volvulus vs., 503 - adynamic or paralytic small bowel obstruction vs., 390 toxic megacolon vs., 471 - colonic ileus and Ogilvie syndrome, 508–511 cecal volvulus vs., 507 differential diagnosis, 509–510 ileus or dilation, differential diagnosis, 453 ileus vs., 387 - differential diagnosis, 387 - gallstone, 403 - intestinal scleroderma vs., 377 Iliocolitis, mesenteric adenitis and enteritis associated with, 357 Imaging of bariatric surgery, 280–285 Immunologic disorders - celiac-sprue disease vs., 366 - Crohn disease associated with, 372 - intestinal lymphangiectasia associated with, 385 - intestinal scleroderma associated with, 378 Immunosuppression - leukemia and lymphoma associated with, 56 - pneumatosis of intestine vs., 395 - post-transplant lymphoproliferative disorder associated with, 52 Incisions, abdominal. See Abdominal incision and injection sites. Infarct/infarction - acute myocardial infarction, ileus associated with, 387 - hepatic, 718–721 - omental infarct, 88–91 differential diagnosis, 89–90 epiploic appendagitis vs., 499 - splenic. See Splenic infarction. Infected pancreatic necrosis, 991 Infections - acalculous cholecystitis associated with, 908 - ascites associated with, 86 - bacterial. See Bacterial infections. - biliary. See Ascending cholangitis. - chronic gallbladder infection, gallbladder carcinoma associated with, 957 - colonic ileus and Ogilvie syndrome associated with, 510 - fungal hepatic TB and fungal infections, 604–607 infectious colitis associated with, 460 microabscesses, splenic infection and abscess associated with, 556 microsporidia, intestinal, 361, 362 - hepatic arterioportal shunt associated with, 697 hepatic infarction associated with, 719

- hepatic, opportunistic. See Hepatic opportunistic infection. - hepatic TB and fungal infections, 604–607 associated abnormalities, 605 differential diagnosis, 605 image gallery, 604, 606–607 - leukemia and lymphoma vs., 56 - opportunistic hepatic. See Opportunistic hepatic infection. intestinal. See Opportunistic intestinal infection. splenic, post-transplant lymphoproliferative disorder vs., 52 - parasitic. See Parasitic infections. - peritonitis associated with, 78 - protozoan Entamoeba histolytica, hepatic amebic abscess associated with, 609 infectious colitis associated with, 460 intestinal, 361 - rectal carcinoma vs., 531 - sclerosing mesenteritis associated with, 82 - splenic infection and abscess. See Splenic infection and abscess. - splenomegaly and hypersplenism associated with, 559, 560 - tuberculosis. See Tuberculosis. - viral. See Viral infections. Infectious aortitis, aortoenteric fistula associated with, 329 Infectious ascites, ascites vs., 86 Infectious colitis, 458–463 - colon carcinoma vs., 525 - colonic ileus and Ogilvie syndrome vs., 510 - Crohn disease vs., 372 - differential diagnosis, 459 - epiploic appendagitis vs., 499 - image gallery, 458, 461–463 - ischemic colitis vs., 475 - neutropenic colitis vs., 465 - risk factors, 460 - toxic megacolon associated with, 471 - ulcerative colitis vs., 467 Infectious esophagitis, radiation esophagitis vs., 175 Infectious ileitis or colitis, Crohn disease vs., 372 Infectious lymphadenopathy, superior vena cava obstruction associated with, 37 Inferior vena cava - absence, congenital absence of hepatic segments associated with, 599 - anatomy (graphic), 5 - anomalies, malrotation of small intestine associated with, 349 - occlusion, transjugular intrahepatic portosystemic shunt vs., 750 Infiltrating disorders, splenic infection and abscess vs., 556 Infiltrating pancreatic carcinoma, acute pancreatitis and complications vs., 992 Infiltration - fatty infiltration of pancreatic head, asymmetric: pancreatic ductal carcinoma vs., 1036

xxix

INDEX - focal fatty infiltration, pancreatic: pancreatic lipomatous pseudohypertrophy vs., 1013 - ileocecal valve lipoma and lipomatous infiltration, 435 - multifocal fatty infiltration of steatosis and steatohepatitis, hepatic metastases and lymphoma vs., 846 Infiltration of peripancreatic fat planes, differential diagnosis, 974 Inflammation - duodenal, duodenal ulcer vs., 319 - mass or inflammation of ileocecal area, differential diagnosis, 453 - periportal edema/inflammation, peribiliary cysts vs., 677 Inflammatory bowel disease. See also Colitis; Crohn disease. - colorectal trauma vs., 515 - glycogen storage disease vs., 679 - steatosis and steatohepatitis associated with, 634 Inflammatory disorders - chronic, amyloidosis associated with, 27 - extrinsic, Zollinger-Ellison syndrome vs., 251 - IgG4-related inflammatory and fibrotic disorders, sclerosing mesenteritis associated with, 82 - intramural pseudodiverticulosis associated with, 207 - peritoneal inclusion cyst associated with, 131 - sclerosing mesenteritis associated with, 82 - splenomegaly and hypersplenism associated with, 559, 560 Inflammatory factors, cytokine-mediated: ileus associated with, 387 Inflammatory hepatic pseudotumor, solitary necrotic nodule vs., 676 Inflammatory polyp - colonic, 518 - esophageal, 227 Inflammatory pseudotumor, hepatic, 802–805 Infundibulum, stone impaction in: Mirizzi syndrome associated with, 920 Inguinal hernia, 92–95 - differential diagnosis, 94 - femoral hernia vs., 97 - image gallery, 92, 95 - obturator hernia vs., 99 Injection granulomas, in abdominal injection sites, 128 Injection sites, abdominal. See Abdominal incision and injection sites. Instrumentation injury - Boerhaave syndrome vs., 217 - esophageal perforation associated with, 213–214 Interstitial cells of Cajal, intestinal GIST associated with, 449 Interstitial edematous pancreatitis, 991 Intestinal (angioneurotic) angioedema, 380–381 - associated abnormalities, 381 - differential diagnosis, 381 - ischemic enteritis vs., 413 Intestinal GIST, 448–449 - associated abnormalities, 449 - differential diagnosis, 449 - intestinal carcinoid tumor vs., 440 xxx

- small bowel carcinoma vs., 443 - staging, grading, & classification, 449 Intestinal lymphangiectasia, 384–385 Intestinal metastases and lymphoma, 444–447 - associated abnormalities, 446 - Crohn disease vs., 372 - differential diagnosis, 445–446 - duodenal carcinoma vs., 335 - duodenal polyps vs., 332 - hamartomatous polyposis syndrome vs., 437 - image gallery, 444, 447 - intestinal carcinoid tumor vs., 440 - intestinal GIST vs., 449 - intestinal lymphangiectasia vs., 385 - intramural (mesenchymal) intestinal tumors vs., 434 - intussusception vs., 399 - radiation enteritis and colitis vs., 427 - small bowel carcinoma vs., 443 - Whipple disease vs., 368 Intestinal neoplasms. See Small intestine neoplasms, benign; Small intestine neoplasms, malignant. Intestinal nonrotation, paraduodenal hernia associated with, 106 Intestinal opportunistic infection. See Opportunistic intestinal infection. Intestinal parasites and infestation, 358–359 - differential diagnosis, 359 - eosinophilic gastroenteritis and esophagitis vs., 176 Intestinal pseudoobstruction, ileus vs., 387 Intestinal scleroderma, 376–379 - associated abnormalities, 378 - differential diagnosis, 377 - genetics, 378 - image gallery, 376–379 - intestinal lymphangiectasia associated with, 385 - SMA (superior mesenteric artery) syndrome vs., 325 - small bowel diverticula vs., 351 Intestinal trauma, intestinal (angioneurotic) angioedema vs., 381 Intestinal tuberculosis, duodenal carcinoma vs., 335 Intraductal mimics of gallstones, artifact, 864 Intraductal papillary mucinous neoplasm - biliary. See Biliary IPMN (intraductal papillary mucinous neoplasm). - pancreatic. See Pancreatic IPMN (intraductal papillary mucinous neoplasm). Intrahepatic arteriovenous fistula, traumatic: hereditary hemorrhagic telangiectasia vs., 727 Intrahepatic bile ducts, peribiliary cysts vs., 677 Intrahepatic biliary obstruction, focal confluent fibrosis vs., 659 Intrahepatic chemoembolization, hepatic infarction associated with, 719 Intrahepatic pigment stone disease. See Recurrent pyogenic cholangitis. Intrahepatic stones secondary to biliary stricture, recurrent pyogenic cholangitis vs., 879 Intramural benign colonic tumor, villous adenoma vs., 522 Intramural benign esophageal tumors, 224–225 - differential diagnosis, 225

INDEX - esophageal carcinoma vs., 229 - esophageal metastases and lymphoma vs., 233 - fibrovascular polyp vs., 226 - gross pathologic and surgical features, 225 - inflammatory polyp vs., 227 Intramural benign gastric tumors, 290–293 - associated abnormalities, 291 - differential diagnosis, 291 - image gallery, 290, 293 Intramural hematoma, intramural (mesenchymal) intestinal tumors vs., 434 Intramural (mesenchymal) intestinal tumors, 434 Intramural mass, gastric bezoar vs., 261 Intramural pseudodiverticulosis, esophageal, 206–207 - associated abnormalities, 207 - differential diagnosis, 207 Intrapancreatic lipoma, asymmetric fatty lobulation of pancreas vs., 987 Intrapancreatic splenule, pancreatic neuroendocrine tumors vs., 1056 Intraperitoneal fluid, free, after open laparotomy or laparoscopy, 125 Intrasplenic pseudocyst, splenic cyst vs., 573 Intrathoracic stomach, differential diagnosis, 237 Intussusception, 398–401 - differential diagnosis, 399 - gallstone ileus vs., 403 - image gallery, 398, 401 - jejunogastric, complication of partial gastrectomy, 272 - rectal prolapse and intussusception, 513 - staging, grading, & classification, 400 Iodinated contrast material, biliary artifact, 864 Iron intake, increased: hemochromatosis associated with, 681 Ischemia, due to intrahepatic vessel occlusion: focal nodular hyperplasia associated with, 782 Ischemic bile duct injury, 942–945 Ischemic cholangiopathy. See Ischemic bile duct injury. Ischemic cholangitis, AIDS cholangiopathy vs., 891 Ischemic colitis, 474–477 - colon carcinoma associated with, 526 - colon carcinoma vs., 525 - colonic ileus and Ogilvie syndrome vs., 509 - CT findings acute arterial thromboembolic, 475 hypoperfusion ischemia, 475 mesenteric venous thrombosis, 475 - differential diagnosis, 475–476 - diverticulitis vs., 493–494 - image gallery, 474, 477 - infectious colitis vs., 459 - pneumatosis of intestine vs., 395 - sigmoid, colonic diverticulosis vs., 489 - ulcerative colitis vs., 467 Ischemic enteritis, 412–415 - celiac-sprue disease vs., 365 - differential diagnosis, 413 - image gallery, 412, 415 - intestinal (angioneurotic) angioedema vs., 381 - pneumatosis of intestine vs., 395 - radiation enteritis and colitis vs., 427

- small bowel NSAID stricture vs., 383 - staging, grading, & classification, 414 Ischemic insults, sclerosing mesenteritis associated with, 82 Islet cell tumors. See Pancreatic neuroendocrine tumors. Isolated polycystic liver disease, congenital hepatic fibrosis vs., 591 Ivor Lewis procedure. See Esophagectomy: Ivor Lewis and other procedures.

J Jejunal loop, normal, postoperative pancreas vs., 1020 Jejunogastric intussusception, complication of partial gastrectomy, 272 Juvenile nephronophthisis, congenital hepatic fibrosis associated with, 592 Juvenile polyposis. See Hamartomatous polyposis syndrome.

K

Kaposi sarcoma, 62–63 - clinical subtypes, 63 - colonic, colonic metastases and lymphoma vs., 541 - differential diagnosis, 63 - duodenal polyps vs., 332 - metastatic melanoma vs., 60 - pathology, 63 in HIV/AIDS, 10 Kasabach-Merritt syndrome, hepatic cavernous hemangioma associated with, 774 Kawasaki syndrome, children, gallbladder hydrops and empyema associated with, 894 Keloid (hypertrophic scar), associated with abdominal incision and injection sites, 127 Kidney - CT findings leukemia and lymphoma, 55 metastatic melanoma, 59 post-transplant lymphoproliferative disorder, 51 sickle cell anemia, 23 - HIV/AIDS CT findings, 9 ultrasonographic findings, 9 - imaging findings, in cystic fibrosis, 19 Kidney failure, acute: HELLP syndrome associated with, 734 Kidney failure, chronic - ascites associated with, 86 - duodenal ulcer associated with, 320 - ischemic colitis associated with, 476 Kidney, medullary sponge - Caroli disease associated with, 872 - congenital hepatic fibrosis associated with, 592 Kidney neoplasms, duodenal metastases and lymphoma associated with, 339 Killian-Jamieson diverticulum, Zenker diverticulum vs., 203 xxxi

INDEX KIT germline mutations, intramural benign gastric tumors associated with, 291 KRAS gene mutation, gallbladder carcinoma associated with, 958 KRAS oncogene - colon carcinoma associated with, 526 - duodenal carcinoma associated with, 336 - pancreatic ductal carcinoma associated with, 1036 - pancreatic intraductal papillary mucinous neoplasm (IPMN) associated with, 1050 - small bowel carcinoma associated with, 443 Kuppfer cell sarcoma. See Hepatic angiosarcoma.

L

Large bowel. See Colon. Laryngeal edema, intestinal (angioneurotic) angioedema associated with, 381 Left gastric venous collateral vessel varices, imaging in portal hypertension, 115 Left upper quadrant mass - differential diagnosis, 238 - other: splenomegaly and hypersplenism vs., 560 Leiomyoblastoma, type of intramural benign gastric tumor, 292 Leukemia, 54–57 - CT findings, 55 - desmoid neoplasms vs., 137 - differential diagnosis, 56 - hepatic TB and fungal infections associated with, 605 - hepatomegaly associated with, 689 - image gallery, 54, 57 - metastatic melanoma vs., 60 - staging, grading, & classification, 56 Ligaments of peritoneal cavity, embryology and anatomy, 66 Ligamentum venosum, change in axis of fissure of: congenital absence of hepatic segments associated with, 599 Linitis plastica, gastric: differential diagnosis, 238 Lipodystrophy, diabetic: associated with abdominal incision and injection sites, 127 Lipoma - hepatic. See Hepatic angiomyolipoma and lipoma. - ileocecal valve lipoma and lipomatous infiltration, 435 - intrapancreatic, asymmetric fatty lobulation of pancreas vs., 987 - pancreatic. See also Atypical and rare pancreatic tumors. imaging, 1069 - spermatic cord, inguinal hernia vs., 94 - type of intramural benign gastric tumor, 292 Lipomatosis, pancreatic: agenesis of dorsal pancreas vs., 980 Lipomatous pseudohypertrophy, pancreatic, 1012–1013 - associated abnormalities, 1013 - cystic fibrosis vs., 20 - differential diagnosis, 1013 Liposarcoma - metastatic, hepatic angiomyolipoma and lipoma vs., 799 xxxii

- omental infarct vs., 89 - retroperitoneal, pancreatic lipomatous pseudohypertrophy associated with, 1013 - sclerosing mesenteritis vs., 82 - spermatic cord, inguinal hernia vs., 94 Liposclerotic mesenteritis. See Sclerosing mesenteritis. Liquid drain cleaner, caustic esophagitis associated with, 173 Littoral cell angioma, splenic - CT findings, 575 - key concepts, 575 - MR findings, 575 - ultrasonographic findings, 575 Liver, 584–851 - AD polycystic liver disease. See AD (autosomal dominant) polycystic liver disease. - alcoholic liver disease, 626–629 cirrhosis associated with, 644 differential diagnosis, 627 - alternative or additional source of venous flow, transient hepatic attenuation or intensity difference associated with, 692 - amebic abscess, 608–611 differential diagnosis, 609 hepatic pyogenic abscess vs., 601 - arterioportal shunt, 696–699 - autoimmune hepatitis. See Autoimmune hepatitis. - Budd-Chiari syndrome. See Budd-Chiari syndrome. - cavernous hemangioma. See Hepatic cavernous hemangioma. - cirrhosis. See Cirrhosis. - congenital absence of hepatic segments, 598–599 differential diagnosis, 599 postoperative changes of liver vs., 746 - congenital hepatic fibrosis. See Congenital hepatic fibrosis. - CT findings HIV/AIDS, 9 leukemia and lymphoma, 55 metastatic melanoma, 59 post-transplant lymphoproliferative disorder, 51 sarcoidosis, 29 sickle cell anemia, 23 systemic hypotension, 35 - cyst. See Hepatic cyst. - differential diagnosis, 585–586 cystic hepatic mass, 585 fat-containing liver mass, 585 focal hyperdense hepatic mass on nonenhanced CT, 586 focal hypervascular liver lesion, 585 focal liver lesion with hemorrhage, 585 liver lesion with capsule or halo on MR, 586 liver "mass" with capsular retraction, 585 liver mass with central or eccentric scar, 585 multiple hypodense liver lesions, 585–586 periportal lucency or edema, 586 widespread low attenuation within liver, 586 - displacement by chronic obstructive pulmonary disease, hepatomegaly vs., 689

INDEX - focal confluent fibrosis. See Focal confluent fibrosis, hepatic. - focal hypervascular lesion, differential diagnosis, 585 - focal liver lesion with hemorrhage, differential diagnosis, 585 - focal nodular hyperplasia. See Focal nodular hyperplasia. - glycogen storage disease. See Glycogen storage disease. - HELLP syndrome, 732–735 differential diagnosis, 733 hepatic infarction associated with, 719 hepatic trauma vs., 737 - hemochromatosis. See Hemochromatosis. - hepatomegaly, 688–689 - hereditary hemorrhagic telangiectasia, 726–731 - hydatid cyst. See Hepatic hydatid cyst. - imaging approach, 584–589 anatomy (graphic images), 586 anatomy and embryology, 584 approach to hepatic disease and hepatic mass, 584–585 CT and MR protocols, 584 differential diagnosis, 585–586 image gallery, 587–589 - imaging findings, in cystic fibrosis, 19 - increased arterial inflow, transient hepatic attenuation or intensity difference associated with, 692 - infarction, 718–721 differential diagnosis, 719 infected tissue, hepatic pyogenic abscess associated with, 601 radiation-induced liver disease vs., 741 - injury from toxins, 638–641 differential diagnosis, 639 viral hepatitis vs., 621 - lesion. See Liver lesion. - mass. See Liver mass. - neoplasms. See Hepatic neoplasms, benign; Hepatic neoplasms, malignant. - nodular regenerative hyperplasia. See Nodular regenerative hyperplasia. - opportunistic infection. See Hepatic opportunistic infection. - passive hepatic congestion, 706–709 differential diagnosis, 707 hepatomegaly associated with, 689 viral hepatitis vs., 621 - peliosis hepatis, 722–725 - peribiliary cysts, 677 - periportal lucency or edema, differential diagnosis, 586 - portal vein occlusion. See Portal vein occlusion. - postoperative changes, 744–747 - primary biliary cirrhosis, 652–657 autoimmune hepatitis vs., 631 differential diagnosis, 653 sarcoidosis vs., 29 - progressive injury, hemochromatosis associated with, 681 - pyogenic abscess. See Hepatic pyogenic abscess. - radiation-induced liver disease, 740–743

- regenerative and dysplastic nodules. See Regenerative and dysplastic nodules. - schistosomiasis, 616–619 - solitary necrotic nodule, 676 - steatosis and steatohepatitis. See Steatosis and steatohepatitis. - TB and fungal infections, 604–607 - transient hepatic attenuation or intensity difference, 690–695 differential diagnosis, 691 other causes, postoperative changes of liver vs., 746 - transjugular intrahepatic portosystemic shunt, 748–753 - transplantation, 754–763 - trauma. See Hepatic trauma. - ultrasonographic findings HIV/AIDS, 10 metastatic melanoma, 59 - venoocclusive disease, 716–717 - viral hepatitis. See Viral hepatitis. - widespread low attenuation within liver, differential diagnosis, 586 - Wilson disease, 684–687 differential diagnosis, 685 hepatomegaly associated with, 689 Liver allograft infarction, hepatic pyogenic abscess vs., 601 Liver blood supply - aberrant blood supply, arterioportal shunt associated with, 697 - aberrant venous drainage, arterioportal shunt associated with, 697 Liver cell adenoma. See Hepatic adenoma. Liver disease, chronic advanced: pancreatic lipomatous pseudohypertrophy associated with, 1013 Liver infarction. See Hepatic infarction. Liver laceration, gastroduodenal trauma associated with, 327 Liver lesion - focal hypervascular, differential diagnosis, 585 with hemorrhage, differential diagnosis, 585 - multiple hypodense liver lesions, differential diagnosis, 585–586 - with capsule or halo on MR, differential diagnosis, 586 Liver mass - cystic, differential diagnosis, 585 - fat-containing, differential diagnosis, 585 - with capsular retraction, differential diagnosis, 585 - with central or eccentric scar, differential diagnosis, 585 Liver nodules, multiple: Kaposi sarcoma vs., 63 Liver resection, lobar regeneration after: hepatomegaly vs., 689 Lobar regeneration, after major liver resection, liver displacement by: hepatomegaly vs., 689 Loculated ascites - abdominal abscess vs., 74 - lymphangioma (mesenteric cyst), 133 Lumbar hernia, 102 Lung neoplasms - duodenal metastases and lymphoma associated with, 339 xxxiii

INDEX - superior vena cava obstruction associated with, 37 Lupus vasculitis - definition, 39 - imaging findings, 40 Lymph node disease, CT findings in post-transplant lymphoproliferative disorder, 51 Lymph nodes - anatomy (graphic), 5 - CT findings leukemia and lymphoma, 55 metastatic melanoma, 59 - HIV/AIDS, ultrasonographic findings, 10 Lymphadenitis, tuberculosis vs., 14 Lymphadenopathy - CT findings in sarcoidosis, 29 - femoral hernia vs., 97 - hypervascular, Kaposi sarcoma vs., 63 - infectious, superior vena cava obstruction associated with, 37 - inguinal hernia vs., 94 - mesenteric, differential diagnosis, 67 - metastatic, leukemia and lymphoma vs., 56 - mononucleosis vs., 17 - radiologic findings, in tuberculosis, 13 - regional, duodenal metastases and lymphoma associated with, 339 Lymphangiectasia, intestinal, 384–385 Lymphangioma (mesenteric cyst), 132–135 - differential diagnosis, 133 - image gallery, 132, 134–135 - mucinous cystic pancreatic tumor vs., 1043 - nonneoplastic pancreatic cysts vs., 1031 - splenic cyst vs., 573 - type of intramural benign gastric tumor, 292 Lymphangioma, splenic - CT findings, 575 - key concepts, 575 - MR findings, 576 - ultrasonographic findings, 576 Lymphatic malformation. See Lymphangioma (mesenteric cyst). Lymphatics - anatomy (graphic), 5 - congenital abnormality, intestinal lymphangiectasia associated with, 385 - failure of normal embryologic development, lymphangioma (mesenteric cyst) vs., 133 - obstruction of lacteals, intestinal lymphangiectasia associated with, 385 Lymphocele - biloma vs., 939 - peritoneal inclusion cyst vs., 131 - postoperative, abdominal abscess vs., 73 Lymphoepithelial cyst. See Lymphangioma (mesenteric cyst). Lymphoid hyperplasia, familial polyposis and Gardner syndrome vs., 535 Lymphoma, 54–57 - acute pancreatitis and complications vs., 992 - biliary metastases and lymphoma, 964 xxxiv

- colonic metastases and lymphoma, 541 differential diagnosis, 541 familial polyposis and Gardner syndrome vs., 535 - desmoid neoplasms vs., 137 - differential diagnosis, 56 - diffuse, viral hepatitis vs., 622 - duodenal metastases and lymphoma. See Duodenal metastases and lymphoma. - esophageal metastases and lymphoma. See Esophageal metastases and lymphoma. - gastric, gastric GIST vs., 295 - gastric metastases and lymphoma. See Gastric metastases and lymphoma. - gastric pseudolymphoma, gastric metastases and lymphoma vs., 305 - gastrointestinal, opportunistic intestinal infections vs., 361 - generalized adenopathy in secondary lymphoma, gastric lymphoma associated with, 306 - hepatic metastases and lymphoma. See Hepatic metastases and lymphoma. - hepatic TB and fungal infections associated with, 605 - hepatomegaly associated with, 689 - intestinal metastases and lymphoma. See Intestinal metastases and lymphoma. - Kaposi sarcoma vs., 63 - mesenteric, sclerosing mesenteritis vs., 81 - metastatic melanoma vs., 60 - mucosa-associated lymphoid tissue (MALT) CT findings, 55 gastric lymphoma associated with, 306 - non-Hodgkin amyloidosis associated with, 27 involving pancreas, atypical and rare pancreatic tumors vs., 1069 pathology, in HIV/AIDS, 10 - pancreatic metastases and lymphoma. See Pancreatic metastases and lymphoma. - peritoneal metastases and lymphoma, accessory spleen vs., 549 - retroperitoneal, sclerosing mesenteritis vs., 81 - sarcoidosis vs., 29 - splenic metastases and lymphoma. See Splenic metastases and lymphoma. - splenic, primary CT findings, 575–576 key concepts, 575 MR findings, 576 ultrasonographic findings, 576 - staging, grading, & classification, 56 - superior vena cava obstruction associated with, 37 - unrelated to HIV/AIDS, AIDS-related lymphoma vs., 10 Lymphomatosis - abdominal mesothelioma vs., 141 - peritoneal, peritoneal metastases vs., 146 Lymphomatous/leukemic foci in liver, hepatic TB and fungal infections vs., 605 Lymphoproliferative disorder, post-transplant. See Posttransplant lymphoproliferative disorder.

INDEX

M

Macronodular hepatic lesions, tuberculosis vs., 14 Malabsorption conditions, 402 - classification, 402 - mastocytosis vs., 369 - steatosis and steatohepatitis associated with, 634 Maldigestion, 402 Male genital tuberculosis, radiologic findings, 14 Malignancy - new, post-transplant lymphoproliferative disorder vs., 52 - primary visceral leukemia and lymphoma vs., 56 sclerosing mesenteritis vs., 82 - recurrent, post-transplant lymphoproliferative disorder vs., 52 Malignant abdominal neoplasms - abdominal mesothelioma. See Abdominal mesothelioma. - intestinal lymphangiectasia associated with, 385 - peritoneal metastases. See Peritoneal metastases. - pseudomyxoma peritonei. See Pseudomyxoma peritonei. Malignant ascites, ascites vs., 86 Malignant biliary neoplasms. See Biliary neoplasms, malignant. Malignant colon neoplasms. See Colon neoplasms, malignant. Malignant common bile duct obstruction, choledochal cyst vs., 875–876 Malignant duodenal neoplasms - duodenal carcinoma. See Duodenal carcinoma. - duodenal metastases and lymphoma. See Duodenal metastases and lymphoma. - secondary invasion, duodenal metastases and lymphoma vs., 339 Malignant esophageal neoplasms - carcinoma. See Esophageal carcinoma. - metastases and lymphoma. See Esophageal metastases and lymphoma. Malignant gastric neoplasms - "drop" metastases from, colon carcinoma vs., 525 - gastric carcinoma. See Gastric carcinoma. - gastric GIST. See Gastric GIST. - gastric metastases and lymphoma. See Gastric metastases and lymphoma. Malignant hepatic neoplasms. See Hepatic neoplasms, malignant. Malignant mesenchymoma. See Undifferentiated sarcoma, hepatic. Malignant mesothelioma. See Abdominal mesothelioma. Malignant pancreatic neoplasms. See Pancreatic neoplasms, malignant. Malignant small intestine neoplasms. See Small intestine neoplasms, malignant. Mallory-Weiss syndrome, Boerhaave syndrome vs., 217 Malrotation, colon - cecal volvulus associated with, 507

- sigmoid volvulus associated with, 503 Malrotation, small intestine, 348–349 - associated abnormalities, 349 - congenital absence of hepatic segments associated with, 599 - differential diagnosis, 349 - intestinal nonrotation, paraduodenal hernia associated with, 106 Mastocytosis, systemic, 369 - differential diagnosis, 369 - duodenal ulcer associated with, 320 - gastric ulcer associated with, 250 Meckel diverticulum, 352–355 - differential diagnosis, 353–354 - image gallery, 352, 355 - intussusception vs., 399 - small bowel diverticula vs., 351 - small intestine duplication cyst vs., 350 Meckel-Gruber syndrome, congenital hepatic fibrosis associated with, 592 Mediastinal fibrosis, autoimmune or postradiation: superior vena cava obstruction associated with, 37 Mediastinal mass - Bochdalek hernia vs., 112 - Morgagni hernia vs., 113 Mediastinal structures, normal: intramural benign esophageal tumors vs., 225 Mediastinal tumor, intramural benign esophageal tumors vs., 225 Mediastinitis, fibrosing: superior vena cava obstruction associated with, 37 Medullary sponge kidney - Caroli disease associated with, 872 - congenital hepatic fibrosis associated with, 592 Megacolon - adult. See Colonic ileus and Ogilvie syndrome. - functional, sigmoid volvulus vs., 503 - toxic. See Toxic megacolon. Melanoma. See Metastatic melanoma. Ménétrier disease, 256–257 - associated abnormalities, 257 - differential diagnosis, 257 - gastric carcinoma vs., 300 Mesenteric adenitis and enteritis, 356–357 - appendicitis vs., 480 - associated abnormalities, 357 - Crohn disease vs., 372 - differential diagnosis, 357 - Meckel diverticulum vs., 353–354 Mesenteric adenopathy, complication of small intestine transplantation, 432 Mesenteric and small bowel trauma, 416–421 - differential diagnosis, 416 - hepatic trauma associated with, 738 - image gallery, 416, 419–421 - systemic hypotension vs., 35 Mesenteric cyst. See Lymphangioma (mesenteric cyst). Mesenteric edema, sclerosing mesenteritis vs., 81–82 Mesenteric ischemia, acute. See Ischemic enteritis. Mesenteric lipodystrophy. See Sclerosing mesenteritis. xxxv

INDEX Mesenteric lymphadenopathy, differential diagnosis, 67 Mesenteric lymphoma, sclerosing mesenteritis vs., 81 Mesenteric mass (solid), differential diagnosis, 67 Mesenteric panniculitis. See Sclerosing mesenteritis. Mesenteric varices, imaging in portal hypertension, 115–116 Mesenteric vessels, twisting and occlusion: small bowel obstruction associated with, 390 Mesenteritis - complication of small intestine transplantation, 431–432 - sclerosing. See Sclerosing mesenteritis. Mesentery - CT findings in metastatic melanoma, 59 - imaging approach, 66–71 differential diagnosis, 67–68 embryology and relevant anatomy, 66 image gallery, 71 - long, cecal volvulus associated with, 507 - misty (infiltrated), differential diagnosis, 68 - postoperative fat necrosis in mesentery, postoperative pancreas vs., 1020 - small intestine tumors extending into mesentery, desmoid neoplasms vs., 139 Mesothelioma, abdominal. See Abdominal mesothelioma. Metabolic disturbance, colonic ileus and Ogilvie syndrome associated with, 510 Metabolic syndrome, colonic diverticulosis associated with, 489–490 Metachronous carcinomas, colon carcinoma associated with, 526 Metastases - biliary metastases and lymphoma, 964 - colonic metastases and lymphoma, 541 differential diagnosis, 541 familial polyposis and Gardner syndrome vs., 535 - cystic AD polycystic liver disease vs., 595 biliary cystadenocarcinoma vs., 834 hepatic hydatid cyst vs., 613 - duodenal metastases and lymphoma. See Duodenal metastases and lymphoma. - esophageal metastases and lymphoma. See Esophageal metastases and lymphoma. - from primary tumors, metastatic melanoma vs., 60 - gastric metastases and lymphoma. See Gastric metastases and lymphoma. - hepatic metastases and lymphoma. See Hepatic metastases and lymphoma. - hepatomegaly associated with, 689 - hypervascular metastases, peliosis hepatis vs., 722 - intestinal metastases and lymphoma. See Intestinal metastases and lymphoma. - leukemia and lymphoma vs., 56 - liposarcoma, hepatic angiomyolipoma and lipoma vs., 799 - pancreatic metastases and lymphoma. See Pancreatic metastases and lymphoma. - peritoneal metastases and lymphoma, accessory spleen vs., 549 - post-treatment, hepatic amebic abscess vs., 609 xxxvi

- splenic metastases and lymphoma. See Splenic metastases and lymphoma. - teratoma, hepatic angiomyolipoma and lipoma vs., 799 Metastatic lymphadenopathy, leukemia and lymphoma vs., 56 Metastatic melanoma, 58–61 - differential diagnosis, 60 - duodenal metastases and lymphoma associated with, 339 - genetics, 60 - image gallery, 58, 61 - staging, grading, & classification, 60 Microsporidia infection, intestinal, 361, 362 Midgut carcinoids, 439 Miliary hepatic lesions, tuberculosis vs., 14 Milk of calcium bile, 928–929 - associated abnormalities, 929 - differential diagnosis, 929 - porcelain gallbladder associated with, 927 - vicarious excretion of contrast medium vs., 153 Mirizzi syndrome, 918–921 - associated abnormalities, 920 - differential diagnosis, 919 - image gallery, 918, 921 - staging, grading, & classification, 920 Moniliasis. See Candida esophagitis. Mononucleosis, 16–17 Monozygotic twins, ulcerative colitis associated with, 468 Morgagni hernia, 113 - differential diagnosis, 113 - gastric volvulus associated with, 264 - traumatic diaphragmatic rupture vs., 121 Mucin-producing cholangiocarcinoma. See Biliary IPMN (intraductal papillary mucinous neoplasm). Mucin-producing neoplasm of appendix, pseudomyxoma peritonei associated with, 150 Mucinous cystadenoma or cystadenocarcinoma. See Mucinous cystic pancreatic tumor. Mucinous cystic pancreatic tumor, 1042–1047 - atypical and rare pancreatic tumors vs., 1069 - differential diagnosis, 1043–1044 - image gallery, 1042, 1045–1047 - nonneoplastic pancreatic cysts vs., 1031 - pancreatic intraductal papillary mucinous neoplasm (IPMN) vs., 1050 - pancreatic serous cystadenoma vs., 1027 - pancreatic solid and pseudopapillary neoplasm vs., 1063 Mucinous macrocystic adenoma. See Mucinous cystic pancreatic tumor. Mucocele of appendix, 484–487 - appendiceal tumors vs., 540 - associated abnormalities, 485 - differential diagnosis, 485 - image gallery, 484, 486–487 Mucocele of gallbladder. See Gallbladder hydrops and empyema. Mucopolysaccaridoses, umbilical hernia associated with, 103 Mucosa-associated lymphoid tissue (MALT) - CT findings, 55

INDEX - gastric lymphoma associated with, 306 Mucosal ulceration of Rokitansky-Aschoff sinuses, xanthogranulomatous cholecystitis associated with, 911 Mucous ductal ectasia of biliary tree. See Biliary IPMN (intraductal papillary mucinous neoplasm). Multifocal hepatocellular carcinoma, nodular regenerative hyperplasia vs., 662 Multiple aphthous ulcers, Zollinger-Ellison syndrome vs., 251 Multiple endocrine syndrome type 1 - duodenal ulcer associated with, 320 - gastric ulcer associated with, 250 - pancreatic neuroendocrine tumors associated with, 1056 - Zollinger-Ellison syndrome associated with, 251 Multiple hamartoma (Cowden syndrome). See Hamartomatous polyposis syndrome. Mycobacterial infections - intestinal, 361, 362 - intestinal lymphangiectasia associated with, 385 Myeloma - amyloidosis associated with, 27 - hepatomegaly associated with, 689 Myeloproliferative disorders - nodular regenerative hyperplasia associated with, 664 - primary biliary cirrhosis vs., 653 Myenteric ganglia in Auerbach plexus, idiopathic abnormality of: esophageal achalasia associated with, 182 Myxedema, Chagas disease of esophagus vs., 165

N

Nasogastric intubation esophagitis, radiation esophagitis vs., 175 Necrotizing colitis, colon carcinoma associated with, 526 Necrotizing enterocolitis, pneumatosis of intestine vs., 395 Necrotizing pancreatitis, 991 Nephrolithiasis, glycogen storage disease vs., 679 Neurofibromatosis type 1 - hepatic angiosarcoma associated with, 839 - intestinal GIST associated with, 449 - intramural benign gastric tumors associated with, 291 - type of intramural benign gastric tumor, 292 Neuromuscular disorders of esophagus, esophageal achalasia vs., 182 Neuropathy, Chagas disease of esophagus vs., 165 Neutropenia, hepatic TB and fungal infections associated with, 605 Neutropenic colitis (typhlitis), 464–465 - differential diagnosis, 465 - ulcerative colitis vs., 468 Nitrites or nitrates, gastric carcinoma associated with, 300 Nodular hyperplasia, focal. See Focal nodular hyperplasia. Nodular panniculitis, systemic. See Sclerosing mesenteritis. Nodular regenerative hyperplasia, 662–667 - associated abnormalities, 663 - cirrhosis vs., 644 - differential diagnosis, 662

- hepatocellular carcinoma vs., 808 - image gallery, 662, 665–667 - regenerative and dysplastic nodules vs., 670 Nodular transformation, sclerosing angiomatoid (SANT), splenic - CT findings, 575 - key concepts, 575 - MR findings, 576 Nodule, solitary necrotic, hepatic, 676 Nodules, regenerative and dysplastic. See Regenerative and dysplastic nodules. Non-Hodgkin lymphoma. See also Lymphoma. - amyloidosis associated with, 27 - involving pancreas, atypical and rare pancreatic tumors vs., 1069 - pathology, in HIV/AIDS, 10 Nonalcoholic steatohepatitis (NASH). See also Steatosis and steatohepatitis. - alcoholic liver disease vs., 627 - hepatomegaly associated with, 689 - steatosis and steatohepatitis associated with, 634 Noncirrhotic nodulation. See Nodular regenerative hyperplasia. Nonneoplastic pancreatic cysts, 1030–1033 - differential diagnosis, 1031 - image gallery, 1030, 1033 - mucinous cystic pancreatic tumor vs., 1044 - staging, grading, & classification, 1032 Nonsteroidal anti-inflammatory drugs (NSAIDs) - duodenal ulcer associated with, 320 - duodenitis associated with, 317 - gastric ulcer associated with, 250 - gastritis associated with, 245 - small bowel NSAID stricture, 382–383 Nontropical sprue. See Celiac-sprue disease. Normal fatty lobulation, cystic fibrosis vs., 20 Normal jejunal loop, postoperative pancreas vs., 1020 Nutritional disorders. See also Diet. - Crohn disease associated with, 372 - deficiencies, intestinal lymphangiectasia associated with, 385 - poor, recurrent pyogenic cholangitis associated with, 880

O

Obesity - gallbladder carcinoma associated with, 957 - pancreatic ductal carcinoma associated with, 1036 - steatosis and steatohepatitis associated with, 634 Obturator hernia, 98–99 - differential diagnosis, 99 - femoral hernia vs., 97 Occult gastrointestinal bleeding, differential diagnosis, 344 Odynophagia, differential diagnosis, 158 Ogilvie syndrome. See Colonic ileus and Ogilvie syndrome. Omental caking. See Peritoneal metastases.

xxxvii

INDEX Omental infarct, 88–91 - differential diagnosis, 89–90 - epiploic appendagitis vs., 499 - image gallery, 88, 91 Omental mass (solid), differential diagnosis, 67 Omental mesenteric metastases, desmoid neoplasms vs., 137 Omental torsion, omental infarct associated with, 90 Omental varices, imaging: in portal hypertension, 115 Omentum - anatomy (graphics), 69–70 - CT findings in leukemia and lymphoma, 55 - embryology and anatomy, 66 - postoperative fat necrosis in greater omentum, postoperative pancreas vs., 1020 Omphalocele - malrotation of small intestine associated with, 349 - umbilical hernia vs., 103 Operative trauma, colonic ileus and Ogilvie syndrome associated with, 510 Opioid (narcotic) use, ileus associated with, 387 Opportunistic hepatic infection - post-transplant lymphoproliferative disorder vs., 52 - primary biliary cirrhosis vs., 653 - sarcoidosis vs., 29 - steatosis and steatohepatitis vs., 634 - venoocclusive disease vs., 717 Opportunistic intestinal infection, 360–363 - bacterial, 361 - celiac-sprue disease vs., 365 - complication of small intestine transplantation, 432 - Crohn disease vs., 372 - Cryptosporidium, 361, 362 - cytomegalovirus, 361, 362 - differential diagnosis, 361 - Giardia, 361 - image gallery, 360, 363 - infectious colitis, 361–362 - intestinal lymphangiectasia vs., 385 - Kaposi sarcoma vs., 63 - microsporidia, 361 - mycobacterial, 361, 362 - post-transplant lymphoproliferative disorder vs., 52 - protozoan, 361 - Whipple disease vs., 368 Opportunistic splenic infection, post-transplant lymphoproliferative disorder vs., 52 Oral contraceptives - desmoid neoplasms associated with, 38 - focal nodular hyperplasia associated with, 782 - hepatic adenoma associated with, 787 - hepatic angiosarcoma associated with, 839 Oral thrush, Candida esophagitis associated with, 163 Orbital pseudotumor, sclerosing mesenteritis associated with, 82 Oriental cholangitis. See Recurrent pyogenic cholangitis. Osler-Weber-Rendu syndrome. See Hereditary hemorrhagic telangiectasia. Ossified scar, associated with abdominal incision and injection sites, 127–128 xxxviii

Ovarian cyst, peritoneal inclusion cyst vs., 131 Ovarian cystic mass - appendiceal tumors vs., 540 - mucocele of appendix vs., 485 Ovarian follicle, peritoneal inclusion cyst vs., 131 Ovarian neoplasms - colon carcinoma vs., 525 - peritoneal inclusion cyst vs., 131 Oxalic acid, caustic esophagitis associated with, 173

P

p53 gene deletion, colon carcinoma associated with, 526 p53 gene mutation, duodenal carcinoma associated with, 336 Pancreas, 972–1071 - acute pancreatitis and complications. See Acute pancreatitis and complications. - agenesis of dorsal pancreas, 980 differential diagnosis, 980 malrotation of small intestine associated with, 349 pancreas divisum vs., 984 - annular. See Annular pancreas. - asymmetric fatty lobulation of pancreas, 986–987 - atrophy or fatty replacement, differential diagnosis, 973 - autoimmune (IgG4) pancreatitis. See Autoimmune (IgG4) pancreatitis. - calcifications, differential diagnosis, 974 - chronic pancreatitis. See Chronic pancreatitis. - CT findings leukemia and lymphoma, 55 metastatic melanoma, 59 post-transplant lymphoproliferative disorder, 51 - differential diagnosis, 973–974 atrophy or fatty replacement of pancreas, 973 cystic pancreatic mass, 973 dilated pancreatic duct, 973–974 hypervascular pancreatic mass, 973 hypovascular pancreatic mass, 973 infiltration of peripancreatic fat planes, 974 pancreatic calcifications, 974 - ectopic pancreatic tissue. See Ectopic pancreatic tissue. - edematous pancreatitis. See Edematous pancreatitis. - enudation, 1019 - groove pancreatitis, 1004–1007 differential diagnosis, 1004 pancreatic ductal carcinoma vs., 1036 - HIV/AIDS CT findings, 9 ultrasonographic findings, 9 - imaging approach, 972–979 anatomy (graphic image), 974 approach to normal pancreas, 972–973 differential diagnosis, 973–974 embryology and normal variants, 972 image gallery, 974–979 imaging protocols, 972 - infiltration of peripancreatic fat planes, differential diagnosis, 974

INDEX - lipomatous pseudohypertrophy, 1012–1013 cystic fibrosis vs., 20 differential diagnosis, 1013 - mass. See Pancreatic mass. - neoplasms. See Pancreatic neoplasms, benign; Pancreatic neoplasms, malignant. - nonneoplastic pancreatic cysts, 1030–1033 differential diagnosis, 1031 mucinous cystic pancreatic tumor vs., 1044 - pancreas divisum, 982–985 agenesis of dorsal pancreas vs., 980 differential diagnosis, 983–984 - pancreatitis. See Pancreatitis. - postoperative, 1018–1021 - progressive injury, hemochromatosis associated with, 681 - senescent change chronic pancreatitis vs., 1002 pancreatic lipomatous pseudohypertrophy vs., 1013 - shock pancreas acute pancreatitis and complications vs., 992 CT findings, 35 pancreatic trauma vs., 1015 - transplantation, 1022–1025 - trauma, 1014–1017 chronic pancreatitis associated with, 1002 differential diagnosis, 1015 systemic hypotension vs., 35 Pancreas divisum, 982–985 - agenesis of dorsal pancreas vs., 980 - anatomy, 984 - associated abnormalities, 984 - differential diagnosis, 983–984 - image gallery, 982, 985 - staging, grading, & classification, 984 Pancreatecomy - central, 1019 - distal, 1019 Pancreatic abscess, complication of pancreatic surgery, 1019 Pancreatic adenocarcinoma. See Pancreatic ductal carcinoma. Pancreatic cystic neoplasms - choledochal cyst vs., 876 - cystic fibrosis vs., 20 Pancreatic cysts, nonneoplastic, 1030–1033 - differential diagnosis, 1031 - mucinous cystic pancreatic tumor vs., 1044 Pancreatic duct - dilated, differential diagnosis, 973–974 - pseudostenosis, 864 Pancreatic ductal anatomy, other anatomic variants: pancreas divisum vs., 984 Pancreatic ductal carcinoma, 1034–1041 - agenesis of dorsal pancreas vs., 980 - annular pancreas vs., 981 - associated abnormalities, 1036 - atypical and rare pancreatic tumors vs., 1069 - autoimmune (IgG4) cholangitis vs., 932 - autoimmune (IgG4) pancreatitis vs., 1009 - biliary trauma vs., 947

chronic pancreatitis vs., 1002 differential diagnosis, 1036 duodenal carcinoma vs., 335 extrinsic invasion, duodenal ulcer vs., 319–320 genetics, 1036 groove pancreatitis vs., 1004 image gallery, 1034, 1037–1041 infiltrating, acute pancreatitis and complications vs., 992 pancreas divisum vs., 983 pancreatic intraductal papillary mucinous neoplasm (IPMN) vs., 1049 - pancreatic metastases and lymphoma vs., 1065 - pancreatic neuroendocrine tumors vs., 1056 - pancreatic solid and pseudopapillary neoplasm vs., 1063 - staging, grading, & classification, 1036–1037 Pancreatic epithelial (true) cyst, mucinous cystic pancreatic tumor vs., 1043 Pancreatic fistula, complication of pancreatic surgery, 1019 Pancreatic focal fatty infiltration, pancreatic lipomatous pseudohypertrophy vs., 1013 Pancreatic hamartoma, duodenal wall. See Groove pancreatitis. Pancreatic head adenocarcinoma - asymmetric fatty lobulation of pancreas vs., 987 - involving ampulla, ampullary carcinoma vs., 961 Pancreatic head, asymmetric fatty infiltration of: pancreatic ductal carcinoma vs., 1036 Pancreatic injury, hepatic trauma associated with, 738 Pancreatic IPMN (intraductal papillary mucinous neoplasm), 1048–1053 - chronic pancreatitis vs., 1002 - differential diagnosis, 1049–1050 - genetics, 1050 - image gallery, 1048, 1051–1053 - mucinous cystic pancreatic tumor vs., 1043 - nonneoplastic pancreatic cysts vs., 1031 - pancreatic serous cystadenoma vs., 1027 - staging, grading, & classification, 1050 Pancreatic laceration/fracture, gastroduodenal trauma associated with, 327 Pancreatic lipoma, 1069. See also Atypical and rare pancreatic tumors. Pancreatic lipomatosis, agenesis of dorsal pancreas vs., 980 Pancreatic lipomatous pseudohypertrophy, 1012–1013 - associated abnormalities, 1013 - cystic fibrosis vs., 20 - differential diagnosis, 1013 Pancreatic mass - cystic, differential diagnosis, 973 - hypervascular pancreatic mass, differential diagnosis, 973 - hypovascular, differential diagnosis, 973 Pancreatic metastases and lymphoma, 1064–1067 - acute pancreatitis and complications vs., 992 - differential diagnosis, 1065 - image gallery, 1064, 1066–1067 - pancreatic ductal carcinoma vs., 1036 - pancreatic neuroendocrine tumors vs., 1056 -

xxxix

INDEX Pancreatic necrosis - central (disconnected duct syndrome), 991 - infected, 991 Pancreatic neoplasms, benign - cystic choledochal cyst vs., 876 cystic fibrosis vs., 20 - nonneoplastic pancreatic cysts, 1030–1033 differential diagnosis, 1031 mucinous cystic pancreatic tumor vs., 1044 - serous cystadenoma. See Pancreatic serous cystadenoma. Pancreatic neoplasms, malignant - atypical and rare pancreatic tumors, 1068–1071 - ductal carcinoma. See Pancreatic ductal carcinoma. - duodenal metastases and lymphoma associated with, 339 - hypervascular pancreatic mass, differential diagnosis, 973 - hypovascular pancreatic mass, differential diagnosis, 973 - metastases and lymphoma. See Pancreatic metastases and lymphoma. - mucinous cystic pancreatic tumor. See Mucinous cystic pancreatic tumor. - neuroendocrine tumors. See Pancreatic neuroendocrine tumors. - pancreatic head adenocarcinoma asymmetric fatty lobulation of pancreas vs., 987 involving ampulla, ampullary carcinoma vs., 961 - pancreatic IPMN. See Pancreatic IPMN (intraductal papillary mucinous neoplasm). - solid and pseudopapillary neoplasm, 1060–1063 - tumor recurrence, complication of pancreatic surgery, 1020 Pancreatic neuroendocrine tumors, 1054–1059 - atypical and rare pancreatic tumors vs., 1069 - cystic mucinous cystic pancreatic tumor vs., 1043 nonneoplastic pancreatic cysts vs., 1031–1032 - differential diagnosis, 1056 - genetics, 1056 - image gallery, 1054, 1057–1059 - pancreatic ductal carcinoma vs., 1036 - pancreatic metastases and lymphoma vs., 1065 - pancreatic serous cystadenoma vs., 1027 - Zollinger-Ellison syndrome associated with, 251 Pancreatic plasmacytoma, 1069. See also Atypical and rare pancreatic tumors. Pancreatic pseudocyst - abdominal abscess vs., 74 - choledochal cyst vs., 876 - complication of pancreatic surgery, 1019 - intramural benign gastric tumors vs., 291 - lymphangioma (mesenteric cyst), 133 - mucinous cystic pancreatic tumor vs., 1043 - nonneoplastic pancreatic cysts vs., 1031 - pancreatic intraductal papillary mucinous neoplasm (IPMN) vs., 1050

xl

Pancreatic pseudocyst or cystic tumor, small intestine duplication cyst vs., 350 Pancreatic schwannoma, 1069. See also Atypical and rare pancreatic tumors. Pancreatic serous cystadenoma, 1026–1029 - differential diagnosis, 1027 - image gallery, 1026, 1028–1029 - mucinous cystic pancreatic tumor vs., 1043 - nonneoplastic pancreatic cysts vs., 1031 - pancreatic intraductal papillary mucinous neoplasm (IPMN) vs., 1050 - pancreatic neuroendocrine tumors vs., 1056 - pancreatic solid and pseudopapillary neoplasm vs., 1063 Pancreatic solid and pseudopapillary neoplasm, 1060–1063 - differential diagnosis, 1063 - image gallery, 1062–1063 - staging, grading, & classification, 1063 Pancreatic transplantation, 1022–1025 Pancreatic trauma, 1014–1017 - associated abnormalities, 1016 - chronic pancreatitis associated with, 1002 - differential diagnosis, 1015 - hepatic trauma associated with, 738 - image gallery, 1014, 1017 - laceration/fracture, gastroduodenal trauma associated with, 327 - staging, grading, & classification, 1016 - systemic hypotension vs., 35 Pancreatic tuberculosis, radiologic findings, 14 Pancreatic tumor, gastric diverticulum vs., 243 Pancreatic tumors, atypical and rare, 1068–1071 Pancreaticobiliary duct junction, abnormal, gallbladder carcinoma associated with, 957 Pancreatitis - acute edematous pancreatitis autoimmune (IgG4) pancreatitis vs., 1009 involving groove, groove pancreatitis vs., 1004 - acute pancreatitis and complications. See Acute pancreatitis and complications. - autoimmune. See Autoimmune (IgG4) pancreatitis. - chronic. See Chronic pancreatitis. - duodenitis vs., 317 - edematous. See Edematous pancreatitis. - extrinsic inflammation gastric carcinoma vs., 300 gastric metastases and lymphoma vs., 305 - focal, asymmetric fatty lobulation of pancreas vs., 987 - groove pancreatitis, 1004–1007 differential diagnosis, 1004 pancreatic ductal carcinoma vs., 1036 - interstitial edematous pancreatitis, 991 - ischemic enteritis associated with, 413 - necrotizing pancreatitis, 991 - portal vein occlusion associated with, 702 - postoperative, 1019 - with extrapancreatic fat necrosis, omental infarct vs., 89 - with fistula, 406 Pancreatobiliary parasites, 886–889 Pancreatoblastoma, 1069. See also Atypical and rare pancreatic tumors.

INDEX Panniculitis - mesenteric. See Sclerosing mesenteritis. - systemic nodular. See Sclerosing mesenteritis. Parabiliary venous plexus, aberrant venous drainage: arterioportal shunt associated with, 697 Paraduodenal hernia, 104–107 - associated abnormalities, 106 - differential diagnosis, 105–106 - image gallery, 104, 107 - malrotation of small intestine vs., 349 - staging, grading, & classification, 106 - with obstruction, transmesenteric postoperative hernia vs., 110 Paraesophageal hernia, gastric volvulus associated with, 264 Paraesophageal varices, imaging, in portal hypertension, 115 Paralysis of diaphragm. See Diaphragmatic eventration and paralysis. Paralytic ileus. See Ileus, adynamic or paralytic. Paralyzed diaphragm, traumatic diaphragmatic rupture vs., 122 Paraneoplastic syndrome, sclerosing mesenteritis associated with, 82 Paraovarian cyst, peritoneal inclusion cyst vs., 131 Parasitic infections - clonorchiasis biliary IPMN associated with, 968 peripheral (intrahepatic) cholangiocarcinoma associated with, 822 - Cryptosporidium infection, intestinal, 361, 362 - echinococcosis pancreatobiliary. See Pancreatobiliary parasites. splenic infection and abscess associated with, 556 - Echinococcus granulosus and Echinococcus multilocularis, hepatic hydatid cyst associated with, 613 - eosinophilic gastroenteritis and esophagitis vs., 176 - Giardia, intestinal, 361 - intestinal parasites and infestation, 358–359 differential diagnosis, 359 eosinophilic gastroenteritis and esophagitis vs., 176 - pancreatobiliary, 886–889 - recurrent pyogenic cholangitis associated with, 880 Parasympathetic dysfunction, colonic ileus and Ogilvie syndrome associated with, 510 Paraumbilical vein, recanalized: imaging in portal hypertension, 115 Parenteral hyperalimentation, steatosis and steatohepatitis associated with, 634 Parkinsonism, pancreatic lipomatous pseudohypertrophy associated with, 1013 Partial gastrectomy: Bilroth procedures, 270–273 - gastric carcinoma associated with, 300 - image gallery, 270, 273 - imaging findings Bilroth 1 procedure, 271 Bilroth 2 procedure, 271 complications, 271–272 recommendations, 272 surgery for gastric cancer, 271

surgical procedures, 271 Passive hepatic congestion, 706–709 - differential diagnosis, 707 - hepatomegaly associated with, 689 - image gallery, 706, 708–709 - viral hepatitis vs., 621 Pedunculated polyps, colonic, 517 Peliosis hepatis, 722–725 - associated abnormalities, 724 - differential diagnosis, 722 - image gallery, 722, 725 Pelvic floor defect, obturator hernia associated with, 99 Pelvic fractures, colorectal trauma associated with, 515 Pelvic hernia. See Inguinal hernia. Pelvic surgery, peritoneal inclusion cyst associated with, 131 Pemphigoid and epidermolysis of esophagus, 177 - esophageal webs associated with, 178 - Zenker diverticulum vs., 204 Penetrating peptic ulcer, aortoenteric fistula associated with, 329 Peptic stricture, esophageal achalasia associated with, 182 Peptic ulcer disease. See Duodenal ulcer. Perforated duodenal ulcer - acute pancreatitis and complications vs., 992 - barotrauma vs., 49 - gastroduodenal trauma vs., 327 Perforated gastric ulcer, barotrauma vs., 49 Periampullary adenocarcinoma, duodenal carcinoma vs., 335 Periampullary duodenal carcinoma, ampullary carcinoma vs., 961 Periampullary duodenal wall cyst. See Groove pancreatitis. Perianal fistulas - classification, 405–406 - CT findings colovaginal fistula, 406 colovesical fistula to thick-walled bladder, 406 Crohn disease with fistula, 406 diverticulitis with fistula, 406 duodenal fistula, 406 enterocutaneous fistula, 406 gut-to-gut fistula, 406 pancreatitis with fistula, 406 - enteric fistulas and sinus tracts associated with, 407 - MR findings, 405 - MR findings for perianal fistulas, 405–406 Periaortitis, aortoenteric fistula vs., 329 Peribiliary cysts, 677 Pericardial effusion, passive hepatic congestion associated with, 707 Pericardial fat pad, Morgagni hernia vs., 113 Pericarditis, constrictive. See Constrictive pericarditis. Pericecal internal hernia - paraduodenal hernia vs., 106 - with obstruction, transmesenteric postoperative hernia vs., 110 Perineal hernia, obturator hernia vs., 99 Peripancreatic fat planes, infiltration of: differential diagnosis, 974 xli

INDEX Peripancreatic gastrointestinal stromal tumor, pancreatic neuroendocrine tumors vs., 1056 Peripheral (intrahepatic) cholangiocarcinoma, 820–825 - associated abnormalities, 822 - autoimmune (IgG4) cholangitis vs., 932 - biliary papillomatosis vs., 965 - biliary trauma vs., 947 - differential diagnosis, 882–822 - duodenal carcinoma vs., 335 - epithelioid hemangioendothelioma vs., 827 - fibrolamellar carcinoma vs., 815–816 - focal confluent fibrosis vs., 659 - hepatic cavernous hemangioma vs., 774 - hepatic inflammatory pseudotumor vs., 803–804 - hepatic metastases and lymphoma vs., 846 - hepatocellular carcinoma vs., 808 - image gallery, 820, 823–825 - Mirizzi syndrome vs., 919 - pancreatobiliary parasites vs., 888 - postoperative changes of liver vs., 746 - recurrent pyogenic cholangitis vs., 880 - solitary necrotic nodule vs., 676 - staging, grading, & classification, 822 Periportal edema/inflammation, peribiliary cysts vs., 677 Periportal lucency or edema, differential diagnosis, 586 Perisplenic varices, imaging in portal hypertension, 115 Peritoneal carcinomatosis. See also Peritoneal metastases. - ascites associated with, 86 - omental infarct vs., 90 - peritonitis vs., 77 - splenosis vs., 571 Peritoneal cavity - embryology and anatomy, 66 graphic image, 70 - fat-containing lesion, differential diagnosis, 67 Peritoneal endometriosis, splenosis vs., 571 Peritoneal implants. See Peritoneal metastases. Peritoneal inclusion cyst, 130–131 - abdominal mesothelioma vs., 142 - differential diagnosis, 131 - lymphangioma (mesenteric cyst), 133 Peritoneal lymphomatosis, peritoneal metastases vs., 146 Peritoneal mesothelioma. See Abdominal mesothelioma. Peritoneal metastases, 144–147 - abdominal mesothelioma vs., 141 - differential diagnosis, 146 - image gallery, 144, 147 - metastases and lymphoma, accessory spleen vs., 549 - omental infarct vs., 90 - patterns of carcinomatosis, 145 - peritonitis vs., 77 - staging, grading, & classification, 146 - with mucinous ascites, pseudomyxoma peritonei vs., 149 - without mucinous ascites, pseudomyxoma peritonei vs., 149 Peritoneal serous papillary carcinoma, primary: peritoneal metastases vs., 146 Peritoneum - ascites. See Ascites. - CT findings in leukemia and lymphoma, 55 xlii

- imaging approach, 66–71 differential diagnosis, 67–68 embryology and relevant anatomy, 66 image gallery, 71 - portal hypertension and varices, 114–117 - vicarious excretion of contrast medium, 153 differential diagnosis, 153 milk of calcium bile vs., 929 Peritonitis, 76–79 - bacterial, pseudomyxoma peritonei vs., 150 - differential diagnosis, 77–78 - image gallery, 76, 79 - ischemic enteritis associated with, 413 - sclerosing encapsulating peritonitis, 78 - tuberculosis vs., 14 Pernicious anemia, gastric carcinoma associated with, 300 Persimmons, unripe: gastric bezoar associated with, 261 Peutz-Jeghers syndrome. See also Hamartomatous polyposis syndrome. - duodenal polyps associated with, 332 - gallbladder polyps associated with, 953 - pancreatic ductal carcinoma associated with, 1036 - small bowel carcinoma associated with, 443 Pharyngoesophageal diverticulum. See Zenker diverticulum. Pharyngoesophageal junction lesion, differential diagnosis, 157 Pharynx, anatomy, 156 Phrenic ampulla, hiatal hernia vs., 195 Phrygian cap, hyperplastic cholecystoses vs., 924 Physiologic free fluid, ascites vs., 86 Phytobezoar, 261 PKHD1 gene mutation, Caroli disease associated with, 872 Placental bed origin, HELLP syndrome associated with, 733 Pleural effusion - Ménétrier disease associated with, 257 - traumatic diaphragmatic rupture vs., 122 Pleural lesions, Bochdalek hernia vs., 112 Plummer-Vinson (Paterson-Kelly) syndrome, esophageal webs associated with, 178 Pneumatosis coli, primary: familial polyposis and Gardner syndrome vs., 536 Pneumatosis of intestine, 394–397 - complication of small intestine transplantation, 432 - differential diagnosis, 344, 395 - image gallery, 394, 397 - staging, grading, & classification, 396 Pneumobilia, biliary papillomatosis vs., 965 Pneumoperitoneum - differential diagnosis, 68 - from other causes, colorectal trauma vs., 515 Polyarteritis nodosa. See also Vasculitis. - definition, 39 - imaging findings, 39 - ischemic enteritis associated with, 413 Polycystic kidney disease - autosomal dominant. See Autosomal dominant polycystic kidney disease (ADPKD). - autosomal recessive polycystic kidney disease (ARPKD) AD polycystic liver disease associated with, 595 congenital hepatic fibrosis associated with, 592

INDEX - biliary hamartoma associated with, 795 Polycystic liver disease - autosomal dominant. See AD (autosomal dominant) polycystic liver disease. - autosomal recessive, Caroli disease associated with, 872 - biliary hamartoma associated with, 795 - isolated, congenital hepatic fibrosis vs., 591 Polygonal fluid collections, in mesenteric and small bowel trauma, 417 Polymyositis - esophageal scleroderma associated with, 190 - intestinal scleroderma associated with, 378 Polypoid gallbladder carcinoma, gallbladder polyps vs., 953 Polyposis syndromes - duodenal polyps associated with, 332 - familial. See Familial polyposis and Gardner syndrome. - familial adenomatous. See Familial adenomatous polyposis (FAP). - gastric polyps associated with, 288 - hamartomatous. See Hamartomatous polyposis syndrome. - small bowel carcinoma associated with, 443 Polyps - adenomatous. See Adenomatous polyps. - colonic, 516–519 colonic diverticulosis vs., 489 differential diagnosis, 518 - duodenal, 330–333 - fibrovascular, esophageal, 226 - fundic gland polyps, gastric polyps associated with, 288 - gallbladder. See Gallbladder polyps. - gastric, 286–289 - hamartomatous colonic, 518 duodenal, 331 - hyperplastic colonic, 518 duodenal, 331 - inflammatory colonic, 518 esophageal, 227 - pedunculated, colonic, 517 - sessile, colonic, 517 - tubular adenomatous, colonic, 517 - tubulovillous adenomatous, colonic, 517 - villous adenomatous, colonic, 517 Polysplenia, 550–553. See also Asplenia. - accessory spleen vs., 549 - associated syndromes, 550 - differential diagnosis, 552 - image gallery, 550, 553 - imaging, 551–552 - malrotation of small intestine associated with, 349 - splenosis vs., 571 Polyvinyl chloride, hepatic angiosarcoma associated with, 839 Poor nutrition, recurrent pyogenic cholangitis associated with, 880

Porcelain gallbladder, 926–927 - associated abnormalities, 927 - differential diagnosis, 927 - emphysematous cholecystitis vs., 916 - gallbladder carcinoma associated with, 957 - gallstones and sludge vs., 898 - milk of calcium bile vs., 929 Porphyria, Chagas disease of esophagus vs., 165 Portal hypertension and varices, 114–117 - ascites associated with, 86 - differential diagnosis, 116 - esophageal varices associated with, 200 - image gallery, 114, 117 - post-sinusoidal, 116 - pre-sinusoidal, 116 - sinusoidal, 116 Portal vein compression - extrinsic, portal vein occlusion vs., 702 - portal hypertension and varices associated with, 116 Portal vein occlusion, 700–705 - arterioportal shunt associated with, 697 - ascending cholangitis associated with, 883–884 - ascites associated with, 86 - associated abnormalities, 702 - differential diagnosis, 702 - image gallery, 700, 703–705 - portal hypertension and varices associated with, 116 - primary, cirrhosis vs., 644 - staging, grading, & classification, 702 - transient hepatic attenuation or intensity difference associated with, 691–692 - transjugular intrahepatic portosystemic shunt vs., 750 Portal vein, preduodenal: malrotation of small intestine associated with, 349 Portal vein thrombosis. See Portal vein occlusion. Portal venous gas - pneumatosis of intestine associated with, 396 - with bowel infarction, postoperative changes of liver vs., 745 Portomesenteric venous thrombosis, complication of pancreatic surgery, 1019 Portosystemic shunt. See Transjugular intrahepatic portosystemic shunt. Positive-pressure ventilation, barotrauma associated with, 49 Post chemoembolization or ablation, congenital absence of hepatic segments vs., 599 Post-endoscopy, pneumatosis of intestine vs., 395 Post sphincterotomy, gas in biliary tree due to: emphysematous cholecystitis vs., 915 Post-transplant lymphoproliferative disorder, 50–53 - complication of small intestine transplantation, 432 - differential diagnosis, 52 - image gallery, 50, 53 - staging, grading, & classification, 52 Post-traumatic pancreatic atrophy, agenesis of dorsal pancreas vs., 980 Post-treatment metastases, hepatic amebic abscess vs., 609

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INDEX Post-vagotomy effect, esophageal achalasia associated with, 182 Postappendicitis scarring, mucocele of appendix associated with, 485 Postendovascular stent, aortoenteric fistula vs., 329 Posterior hypopharyngeal diverticulum/outpouching. See Zenker diverticulum. Postnecrotic (viral) or alcoholic cirrhosis, primary biliary cirrhosis vs., 653 Postoperative changes - aortoenteric fistula vs., 329 - hiatal hernia vs., 195 - liver, 744–747 Postoperative fat necrosis in mesentery or greater omentum, postoperative pancreas vs., 1020 Postoperative fluid collection, biloma vs., 939 Postoperative lymphocele, abdominal abscess vs., 73 Postoperative pancreas, 1018–1021 - complications, 1019–1020 - differential diagnosis, 1020 - image gallery, 1018, 1021 - imaging central pancreatectomy, 1019 distal pancreatectomy, 1019 enudation, 1019 Frey procedure, 1019 normal findings immediately after Whipple procedure, 1019 Puestow procedure, 1019 Whipple procedure, 1019 Postoperative pancreatitis, 1019 Postoperative seroma, abdominal abscess vs., 73–74 Postoperative state, abdomen, 124–125 Postoperative state, bowel, 422–425 - image gallery, 422, 425 - imaging colonoscopy, 423 endoscopic procedures, 423 enterectomy and anastomosis, 423 enterostomy, 423 gastrointestinal surgery, 423 ileostomy, 423–424 small bowel reservoirs, 424 - intussusception associated with, 400 - pneumatosis of intestine vs., 395 Postoperative state, duodenum: SMA (superior mesenteric artery) syndrome associated with, 325 Postoperative state, esophagus - esophageal achalasia vs., 182 - esophageal motility disturbances vs., 185 - esophageal perforation vs., 213 Postoperative state, liver: hepatic angiomyolipoma and lipoma vs., 799 Postoperative state, stomach - gastric volvulus vs., 263 - gastroparesis vs., 259 Postprandial food, gastric bezoar vs., 261 Postsurgical resection, congenital absence of hepatic segments vs., 599

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Preduodenal portal vein, malrotation of small intestine associated with, 349 Preeclampsia, HELLP syndrome associated with, 733 Pregnancy - steatosis and steatohepatitis associated with, 634 - with HELLP syndrome, hepatic infarction associated with, 719 Presbyesophagus, form of esophageal motility disturbances, imaging, 185 Primary biliary cirrhosis, 652–657 - associated abnormalities, 654 - autoimmune hepatitis vs., 631 - differential diagnosis, 653 - genetics, 654 - image gallery, 652, 655–657 - sarcoidosis vs., 29 Primary bowel tumor - intussusception vs., 399 - radiation enteritis and colitis vs., 427 Primary liver cancer. See Hepatocellular carcinoma. Primary peritoneal serous papillary carcinoma, peritoneal metastases vs., 146 Primary pneumatosis coli, familial polyposis and Gardner syndrome vs., 535–536 Primary portal vein thrombosis, cirrhosis vs., 644 Primary sclerosing cholangitis, 934–937 - AIDS cholangiopathy vs., 891 - ascending cholangitis vs., 883 - associated abnormalities, 936 - autoimmune (IgG4) cholangitis vs., 931–932 - autoimmune hepatitis vs., 631 - biliary trauma vs., 947 - Caroli disease vs., 872 - chemotherapy-induced. See Chemotherapy-induced cholangitis. - choledochal cyst vs., 876 - congenital hepatic fibrosis vs., 591 - Crohn disease associated with, 372 - differential diagnosis, 936 - gallbladder carcinoma associated with, 958 - image gallery, 934, 937 - ischemic bile duct injury vs., 944 - mastocytosis vs., 369 - peripheral (intrahepatic) cholangiocarcinoma associated with, 822 - primary biliary cirrhosis associated with, 654 - recurrent pyogenic cholangitis vs., 879 - sclerosing mesenteritis associated with, 82 - ulcerative colitis associated with, 468 Primary splenic lymphoma - CT findings, 575–576 - key concepts, 575 - MR findings, 576 - ultrasonographic findings, 576 Primary splenic tumors, 574–577 - angiomyolipoma. See Angiomyolipoma and lipoma, hepatic. - angiosarcoma. See Angiosarcoma, splenic; Hepatic angiosarcoma. - benign, splenic cyst vs., 573

INDEX differential diagnosis, 576 hamartoma. See Hamartoma, splenic. hemangioma. See Hemangioma, splenic. image gallery, 574, 577 littoral cell angioma. See Littoral cell angioma, splenic. lymphangioma. See Lymphangioma, splenic. lymphoma. See Primary splenic lymphoma. sclerosing angiomatoid nodular transformation. See Sclerosing angiomatoid nodular transformation (SANT), splenic. - splenic infarction vs., 564 - splenic infection and abscess vs., 555 - splenic metastases and lymphoma vs., 580 Primary visceral malignancy, sclerosing mesenteritis vs., 82 PRKCSH gene mutation, AD polycystic liver disease associated with, 595 Progressive systemic sclerosis - esophageal. See Esophageal scleroderma. - intestinal. See Intestinal scleroderma. Prostate carcinoma, rectal carcinoma vs., 531 Protein-losing gastropathy. See Ménétrier disease. Protein malnutrition, steatosis and steatohepatitis associated with, 634 Protozoan infections - Entamoeba histolytica, hepatic amebic abscess associated with, 609 - infectious colitis associated with, 460 - intestinal, 361 PRSS1 gene mutation - acute pancreatitis associated with, 992 - chronic pancreatitis associated with, 1002 Pseudoaneurysm - complication of acute pancreatitis, 991 - complication of small intestine transplantation, 431 - splenic artery aneurysm or pseudoaneurysm, accessory spleen vs., 549 Pseudodiverticulosis, intramural esophageal, 206–207 Pseudomegacolon. See Colonic ileus and Ogilvie syndrome. Pseudomembranous colitis, diverticulitis vs., 494 Pseudomyxoma peritonei, 148–151 - abdominal mesothelioma vs., 141 - differential diagnosis, 149–150 - image gallery, 148–151 - peritoneal metastases vs., 146 - peritonitis vs., 78 - staging, grading, & classification, 150 Pseudopapillary neoplasm, pancreatic. See Pancreatic solid and pseudopapillary neoplasm. Pseudopneumatosis, pneumatosis of intestine vs., 395 Pseudopolyps, familial polyposis and Gardner syndrome vs., 535–536 Psychiatric disease, sigmoid volvulus associated with, 504 PTEN gene mutation, hamartomatous polyposis syndrome associated with, 437 Puestow procedure, 1019 Pulmonary arteriovenous malformations, hereditary hemorrhagic telangiectasia associated with, 728 Pulmonary diseases, pneumatosis of intestine vs., 395 Pulmonary edema, HELLP syndrome associated with, 734 -

Pulmonary/extrapleural mass, traumatic diaphragmatic rupture vs., 122 Pulmonary lesions - Bochdalek hernia vs., 112 - parenchymal, Morgagni hernia vs., 113 Pulmonary valve disease, passive hepatic congestion associated with, 707 Pulsatile vascular compression artifact, biliary, 864 Pulsion diverticulum, 209 - Boerhaave syndrome vs., 217 - differential diagnosis, 209 - gastric volvulus vs., 263 - hiatal hernia vs., 195 - traction diverticulum vs., 208 Pyloroplasty, gastric bezoar associated with, 261 Pyodema gangrenosum, ulcerative colitis associated with, 468 Pyogenic abscess, hepatic. See Hepatic pyogenic abscess. Pyogenic cholangitis, recurrent. See Recurrent pyogenic cholangitis.

R

Radiation - aortoenteric fistula associated with, 329 - duodenitis associated with, 317 - enteric fistulas and sinus tracts associated with, 407 - hepatic angiosarcoma associated with, 839 - ischemic enteritis associated with, 413 - viral esophagitis associated with, 164 Radiation enteritis and colitis, 426–429 - Crohn disease vs., 372 - differential diagnosis, 427 - diverticulitis vs., 493 - image gallery, 426, 429 - radiation tolerance of intestinal organs, 428 - risk factors, 427–428 - small bowel NSAID stricture vs., 383 - staging, grading, & classification, 428 Radiation esophagitis, 175 - caustic esophagitis vs., 173 - differential diagnosis, 175 - esophageal carcinoma vs., 230 Radiation gastritis, 245 Radiation-induced liver disease, 740–743 Rare pancreatic tumors. See Atypical and rare pancreatic tumors. Recanalized umbilical vein, imaging, in portal hypertension, 115 Reconstruction artifacts, biliary, 863 Rectal carcinoma, 530–533 - differential diagnosis, 531 - genetics, 532 - image gallery, 530, 533 - staging, grading, & classification, 532 Rectal prolapse and intussusception, 513 Rectal villous adenoma, rectal carcinoma vs., 531 Recurrent pyogenic cholangitis, 878–881 - ascending cholangitis vs., 883 - biliary IPMN vs., 967 xlv

INDEX Caroli disease vs., 872 choledochal cyst vs., 876 differential diagnosis, 879–880 image gallery, 878, 881 pancreatobiliary parasites vs., 888 peripheral (intrahepatic) cholangiocarcinoma associated with, 822 Reflux esophagitis, 166–169 - Barrett esophagus vs., 171 - Candida esophagitis vs., 163 - caustic esophagitis vs., 173 - differential diagnosis, 167 - drug-induced esophagitis vs., 174 - esophageal motility disturbances vs., 185 - esophageal perforation vs., 213 - esophageal varices vs., 199 - image gallery, 166, 169 - radiation esophagitis vs., 175 - Schatzki ring vs., 193 - staging, grading, & classification, 168 - viral esophagitis vs., 164 - with stricture esophageal carcinoma vs., 229 esophageal scleroderma vs., 189 - Zenker diverticulum associated with, 204 Regenerative and dysplastic nodules, 668–675 - associated abnormalities, 670 - differential diagnosis, 669–670 - hepatocellular carcinoma vs., 808 - image gallery, 668, 671–675 - postoperative changes of liver vs., 746 - solitary necrotic nodule vs., 676 - staging, grading, & classification, 670 Regional enteritis. See Crohn disease. Regional lymphadenopathy, duodenal metastases and lymphoma associated with, 339 Rejection, complication of small intestine transplantation, 432 Renal failure - acute, HELLP syndrome associated with, 734 - chronic ascites associated with, 86 duodenal ulcer associated with, 320 ischemic colitis associated with, 476 Renal fibrosis, Caroli disease associated with, 872 Renal lesions, tuberculosis vs., 14 Renal nephrotic syndrome, ascites associated with, 86 Renal tuberculosis, radiologic findings, 13 Respiratory motion artifacts, biliary, 863 Retained fecal debris - colonic polyps vs., 518 - familial polyposis and Gardner syndrome vs., 535 Retained foods and pills - familial polyposis and Gardner syndrome vs., 535 - gastric polyps vs., 287 Retained oxidized cellulose (Surgicel), abdominal abscess vs., 74 Retractile mesenteritis. See Sclerosing mesenteritis. Retrogastric varices, imaging, in portal hypertension, 115 Retroperionteal-paravertebral varices, imaging in portal hypertension, 115 -

xlvi

Retroperitoneal fibrosis - aortoenteric fistula vs., 329 - intestinal lymphangiectasia associated with, 385 - primary sclerosing cholangitis associated with, 936 - sclerosing mesenteritis associated with, 82 Retroperitoneal gas, emphysematous cholecystitis vs., 916 Retroperitoneal hemorrhage, ileus associated with, 387 Retroperitoneal liposarcoma, pancreatic lipomatous pseudohypertrophy vs., 1013 Retroperitoneal lymphoma, sclerosing mesenteritis vs., 81 Retroperitoneal neoplasms, intestinal lymphangiectasia associated with, 385 Reye syndrome, steatosis and steatohepatitis associated with, 634 Rheumatoid arthritis - primary biliary cirrhosis associated with, 654 - ulcerative colitis associated with, 468 Rib fractures, hepatic trauma associated with, 738 Riedel lobe, hepatomegaly vs., 689 Riedel thyroiditis, sclerosing mesenteritis associated with, 82 Right heart failure - hepatomegaly associated with, 689 - portal hypertension and varices associated with, 116 Right lower quadrant pain, acute: differential diagnosis, 454 Rim-enhancing hepatic metastases, postoperative pancreas vs., 1020

S

Sacroiliitis, ulcerative colitis associated with, 468 Salted meat, gastric carcinoma associated with, 300 Sarcoidosis, 28–33 - differential diagnosis, 29–30 - hepatic, cirrhosis vs., 644 - HIV/AIDS vs., 10 - image gallery, 28, 31–33 - intestinal lymphangiectasia associated with, 385 - leukemia and lymphoma vs., 56 - primary biliary cirrhosis vs., 653 - splenic infection and abscess vs., 556 - splenic metastases and lymphoma vs., 580 Sarcoma - angiosarcoma. See Angiosarcoma, hepatic. - hepatic angiosarcoma. See Hepatic angiosarcoma. - invading stomach, gastric GIST vs., 295 - Kaposi sarcoma. See Kaposi sarcoma. - liposarcoma. See Liposarcoma. - soft tissue sarcoma, desmoid neoplasms vs., 137 - undifferentiated, hepatic, 842–843 Schatzki ring, 192–193 - differential diagnosis, 193 - esophageal webs vs., 178 Schistosomiasis - hepatic, 616–619 - portal hypertension and varices associated with, 116 Schwannoma - pancreatic, 1069. See also Atypical and rare pancreatic tumors.

INDEX - type of intramural benign gastric tumor, 292 Sciatic hernia, obturator hernia vs., 99 Scleroderma - esophageal. See Esophageal scleroderma. - intestinal. See Intestinal scleroderma. - primary biliary cirrhosis associated with, 654 Sclerosing angiomatoid nodular transformation (SANT), splenic - CT findings, 575 - key concepts, 575 - MR findings, 576 Sclerosing cholangitis. See Primary sclerosing cholangitis. Sclerosing encapsulating peritonitis, 78 Sclerosing mesenteritis, 80–83 - abdominal mesothelioma vs., 142 - associated abnormalities, 82 - desmoid neoplasms vs., 139 - image gallery, 80, 83 - intestinal carcinoid tumor vs., 440 - intestinal lymphangiectasia associated with, 385 - ischemic enteritis vs., 413 - omental infarct vs., 89 Seat belt sign, in mesenteric and small bowel trauma, 417 Seizures, Boerhaave syndrome associated with, 217 Sentinel clot sign, in mesenteric and small bowel trauma, 417 Sepsis, ileus associated with, 387 Septic emboli, splenic infection and abscess associated with, 556 Septicemia, splenic infection and abscess associated with, 556 Seroma - biloma vs., 939 - intramural benign gastric tumors vs., 291 - postoperative, abdominal abscess vs., 73–74 Serous pancreatic cystadenoma. See Pancreatic serous cystadenoma. Sessile polyps, colonic, 517 Shock bowel. See Systemic hypotension. Shock pancreas - acute pancreatitis and complications vs., 992 - CT findings, 35 - pancreatic trauma vs., 1015 SHROOM3 gene mutation, asplenia and polysplenia associated with, 552 Shwachman-Diamond syndrome - cystic fibrosis vs., 20 - pancreatic lipomatous pseudohypertrophy vs., 1013 Sickle cell anemia, 22–25 - differential diagnosis, 24 - genetics, 24 - hepatomegaly associated with, 689 - image gallery, 22, 25 - splenic infection and abscess associated with, 556 - splenomegaly and hypersplenism associated with, 559, 560 Sickle cell trait, 24 Siderosis, hepatocellular carcinoma associated with, 808 Sigmoid diverticulum, giant: colonic diverticulosis vs., 489 Sigmoid ischemic colitis, colonic diverticulosis vs., 489

Sigmoid volvulus, 502–505 - associated abnormalities, 503–504 - cecal volvulus vs., 507 - colonic ileus and Ogilvie syndrome vs., 509 - compound volvulus, 503 - differential diagnosis, 503 - image gallery, 502, 505 Simple hepatic cyst. See Hepatic cyst. Sinus tracts and fistulas, enteric, 404–411 Situs ambiguus, asplenia and polysplenia associated with, 551 Situs inversus, asplenia and polysplenia associated with, 551 Situs solitus, asplenia and polysplenia associated with, 551 Sjögren syndrome, primary biliary cirrhosis associated with, 654 Sludge. See Gallstones and sludge. SMA (superior mesenteric artery) syndrome, 324–325 - differential diagnosis, 325 - intestinal scleroderma vs., 377 - predisposing conditions, 325 SMAD4 gene deletion, colon carcinoma associated with, 526 Small aorta, CT findings in systemic hypotension, 35 Small bowel carcinoma, 442–443 - associated abnormalities, 443 - differential diagnosis, 443 - genetics, 443 - intestinal carcinoid tumor vs., 440 - intramural (mesenchymal) intestinal tumors vs., 434 - primary, intestinal metastases and lymphoma vs., 445 Small bowel diverticula, 351 Small bowel feces sign, in small bowel obstruction, 389 Small bowel NSAID stricture, 382–383 Small bowel obstruction, 388–393 - CT findings closed loop obstruction, 389 extraluminal lesions, 389 extrinsic lesions, 389 intrinsic lesions, 389 small bowel feces sign, 389 strangulating SBO, 389 - differential diagnosis, 344, 390 - ileus vs., 387 - image gallery, 388, 391–393 - staging, grading, & classification, 390 Small bowel stasis, intestinal scleroderma associated with, 378 Small bowel trauma. See Mesenteric and small bowel trauma. Small cell carcinoma, pancreatic, 1069. See also Atypical and rare pancreatic tumors. Small intestine, 342–449 - aneurysmal dilation of small bowel lumen, differential diagnosis, 343 - bezoar, gastric bezoar associated with, 261 - celiac-sprue disease. See Celiac-sprue disease. - closed loop bowel obstruction ischemic enteritis associated with, 413 paraduodenal hernia vs., 105 xlvii

INDEX transmesenteric postoperative hernia vs., 110 - cluster of dilated small bowel, differential diagnosis, 343 - Crohn disease. See Crohn disease. - CT findings amyloidosis, 27 HIV/AIDS, 9 - differential diagnosis, 343–344 aneurysmal dilation of small bowel lumen, 343 cluster of dilated small bowel, 343 irregular diffuse small bowel fold thickening, 344 multiple masses or filling defects, 343 occult GI bleeding, 344 pneumatosis of small intestine or colon, 344 segmental or diffuse small bowel wall thickening, 343–344 small bowel obstruction, 344 stenosis, terminal ileum, 343 - diverticula, 351 - duplication cyst, 350 - enteric fistulas and sinus tracts, 404–411 - fold thickening, irregular or diffuse, differential diagnosis, 1044 - gallstone ileus, 403 - ileus. See Ileus. - imaging approach, 342–347 abnormal small bowel, 342–343 anatomy (graphic images), 345 differential diagnosis, 343–344 embryology and congenital malformation, 342 gross anatomy, 342 image gallery, 346–347 imaging issues, 342 mural small bowel anatomy, 342 - imaging findings, in cystic fibrosis, 19 - injuries, colorectal trauma associated with, 515 - intestinal (angioneurotic) angioedema, 380–381 differential diagnosis, 381 ischemic enteritis vs., 413 - intussusception. See Intussusception. - ischemic enteritis. See Ischemic enteritis. - lymphangiectasia, 384–385 - malabsorption conditions, 402 mastocytosis vs., 369 steatosis and steatohepatitis associated with, 634 - malrotation, 348–349 associated abnormalities, 349 congenital absence of hepatic segments associated with, 599 differential diagnosis, 349 intestinal nonrotation, paraduodenal hernia associated with, 106 - mastocytosis. See Mastocytosis, systemic. - Meckel diverticulum. See Meckel diverticulum. - mesenteric adenitis and enteritis. See Mesenteric adenitis and enteritis. - mesenteric and small bowel trauma, 416–421 - metastatic tumors, metastatic melanoma vs., 60 - motility disturbance, complication of small intestine transplantation, 432 xlviii

- multiple masses or filling defects, differential diagnosis, 343 - necrosis, pneumatosis of intestine vs., 395 - opportunistic infection. See Opportunistic intestinal infection. - parasites and infestation, 358–359 differential diagnosis, 359 eosinophilic gastroenteritis and esophagitis vs., 176 - pneumatosis, 394–397 complication of small intestine transplantation, 432 differential diagnosis, 344, 395 - postoperative state, bowel. See Postoperative state, bowel. - radiation enteritis and colitis. See Radiation enteritis and colitis. - scleroderma. See Intestinal scleroderma. - small bowel NSAID stricture, 382–383 - small bowel obstruction, 388–393 differential diagnosis, 390 ileus vs., 387 - stenosis of terminal ileum, differential diagnosis, 343 - transplantation, 430–433 - trauma. See Mesenteric and small bowel trauma. - wall thickening, segmental or diffuse: differential diagnosis, 343–344 - Whipple disease. See Whipple disease. Small intestine neoplasms, benign - hamartomatous polyposis syndrome. See Hamartomatous polyposis syndrome. - ileocecal valve lipoma and lipomatous infiltration, 435 - intramural (mesenchymal) intestinal tumors, 434 - small intestine tumors extending into mesentery, desmoid neoplasms vs., 139 Small intestine neoplasms, malignant - adenocarcinoma, duodenal carcinoma associated with, 336 - carcinoid tumor, 438–441 - carcinoma. See Small bowel carcinoma. - intestinal GIST, 448–449 differential diagnosis, 449 intestinal carcinoid tumor vs., 440 small bowel carcinoma vs., 443 - metastases and lymphoma. See Intestinal metastases and lymphoma. - primary bowel tumor, intussusception vs., 399 - small bowel obstruction associated with, 390 Small intestine transplantation, 430–433 - complications, 431–432 - image gallery, 430, 433 - indications, 431 Small intestine vasculitis - intestinal metastases and lymphoma vs., 445 - ischemic enteritis vs., 413 - mesenteric and small bowel trauma vs., 417 - small bowel NSAID stricture vs., 383 Smoking - duodenal carcinoma associated with, 335 - gastric carcinoma associated with, 300 - gastric ulcer associated with, 250 - pancreatic ductal carcinoma associated with, 1036

INDEX Soft tissue sarcoma, desmoid neoplasms vs., 137 Solid and pseudopapillary neoplasm, pancreatic. See Pancreatic solid and pseudopapillary neoplasm. Solid organ injuries, colorectal trauma associated with, 515 Solitary colonic filling defect, differential diagnosis, 453 Solitary necrotic nodule, hepatic, 676 Spermatic cord lipoma or liposarcoma, inguinal hernia vs., 94 Sphincter of Oddi spasm, artifact, 864 Sphincterotomy, gas in biliary tree due to: emphysematous cholecystitis vs., 915 Spigelian hernia, 101 - differential diagnosis, 101 - umbilical hernia vs., 103 Spinal cord injury, ileus associated with, 387 SPINK1-trypsin inhibitor, chronic pancreatitis associated with, 1002 Spleen, 544–581 - accessory spleen, 548–549 differential diagnosis, 549 polysplenia vs., 552 splenosis vs., 571 - anatomic abnormalities, splenic infarction associated with, 564 - asplenia, 550–553 differential diagnosis, 552 malrotation of small intestine associated with, 349 - CT findings HIV/AIDS, 9 leukemia and lymphoma, 55 metastatic melanoma, 59 post-transplant lymphoproliferative disorder, 51 sarcoidosis, 29 sickle cell anemia, 23 systemic hypotension, 35 - cystic splenic masses, differential diagnosis, 545 - differential diagnosis, 544–545 cystic splenic mass, 545 diffuse increased attenuation, 545 multiple splenic calcifications, 545 solid splenic masses, 545 splenomegaly, 544 - diffuse increased attenuation, differential diagnosis, 545 - imaging approach, 544–547 approach to abnormal spleen, 544 differential diagnosis, 544–545 embryology, anatomy, and physiology, 544 image gallery, 545–547 imaging issues, 544 - infarction. See Splenic infarction. - multiple splenic calcifications, differential diagnosis, 545 - neoplasms. See Splenic neoplasms. - normal heterogenenous enhancement in arterial phase, splenic infarction vs., 564 - opportunistic infection, post-transplant lymphoproliferative disorder vs., 52 - polysplenia. See Polysplenia. - radiologic findings, in mononucleosis, 17

- splenic infection and abscess. See Splenic infection and abscess. - splenomegaly and hypersplenism. See Splenomegaly and hypersplenism. - splenosis. See Splenosis. - trauma. See Splenic trauma. - wandering, gastric volvulus associated with, 264 Splenectomy, asplenia vs., 552 Splenic abscess. See Splenic infection and abscess. Splenic artery aneurysm or pseudoaneurysm, accessory spleen vs., 549 Splenic calcifications, multiple: differential diagnosis, 545 Splenic cleft, splenic trauma vs., 567 Splenic cyst, 572–573 - differential diagnosis, 573 - primary splenic tumors vs., 576 - splenic infarction vs., 563 - splenic trauma vs., 568 Splenic fracture. See Splenic trauma. Splenic hematoma, primary splenic tumors vs., 576 Splenic infarction, 562–565 - differential diagnosis, 563–564 - image gallery, 562, 565 - infection and abscess vs., 555 - metastases and lymphoma vs., 580 - radiologic findings, in mononucleosis, 17 - systemic hypotension vs., 35 - trauma vs., 567–568 Splenic infection and abscess, 554–557 - CT findings echinococcal (hydatid) cyst, 555 fungal microabscesses, 555 pyogenic abscess, 555 - cyst vs., 573 - differential diagnosis, 555–556 - genetics, 556 - image gallery, 554, 557 - infarction vs., 563–554 - metastases and lymphoma vs., 580 - primary splenic tumors vs., 576 - splenomegaly and hypersplenism vs., 560 - staging, grading, & classification, 556 - trauma vs., 567 Splenic laceration. See Splenic trauma. Splenic lymphoma, primary - CT findings, 575–576 - key concepts, 575 - MR findings, 576 - ultrasonographic findings, 576 Splenic masses, cystic, differential diagnosis, 545 Splenic metastases and lymphoma, 578–583. See also Primary splenic lymphoma. - differential diagnosis, 580 - image gallery, 578, 581 - primary splenic tumors vs., 576 - splenic cyst vs., 573 Splenic neoplasms - primary splenic tumors. See Primary splenic tumors. - splenic cyst. See Splenic cyst. - splenic metastases and lymphoma. See Splenic metastases and lymphoma. xlix

INDEX Splenic rupture, radiologic findings in mononucleosis, 17 Splenic trauma, 566–569 - associated abnormalities, 568 - differential diagnosis, 567–5–568 - gastroduodenal trauma associated with, 327 - hepatic trauma associated with, 738 - image gallery, 566, 569 - infarction vs., 563 - infection and abscess vs., 555 - splenomegaly and hypersplenism vs., 560 - splenosis associated with, 571 - staging, grading, & classification, 568 - systemic hypotension vs., 35 Splenic tumors, primary. See Primary splenic tumors. Splenic vein thrombosis, portal hypertension and varices associated with, 116 Splenomegaly and hypersplenism, 558–561 - differential diagnosis, 544, 560 - image gallery, 558, 561 - intestinal metastases and lymphoma associated with, 446 - mononucleosis vs., 17 - radiologic findings, in mononucleosis, 17 Splenosis, 570–571 - accessory spleen vs., 549 - differential diagnosis, 571 - intramural benign gastric tumors vs., 291 - polysplenia vs., 552 Splenule. See Accessory spleen. Spontaneous hemorrhage - HELLP syndrome vs., 733 - hepatic trauma vs., 737 Squamous cell carcinoma - esophageal carcinoma associated with, 230 - rectal carcinoma associated with, 532 Status asthmaticus, Boerhaave syndrome associated with, 217 Steatosis and steatohepatitis, 632–637. See also Nonalcoholic steatohepatitis (NASH). - associated abnormalities, 634 - differential diagnosis, 634 - focal hepatic angiomyolipoma and lipoma vs., 799 hepatic infarction vs., 719 radiation-induced liver disease vs., 741 - glycogen storage disease vs., 679 - hepatic adenoma associated with, 787 - hepatic injury from toxins vs., 639 - hepatocellular carcinoma associated with, 808 - image gallery, 632, 636–637 - multifocal fatty infiltration, hepatic metastases and lymphoma vs., 846 - nonalcoholic, alcoholic liver disease vs., 627 - viral hepatitis vs., 621 - Wilson disease vs., 685 Stercoral ulceration. See Fecal impaction and stercoral ulceration. Steroid agents - gastric ulcer associated with, 250 - pneumatosis of intestine vs., 395 l

Steroids, anabolic - hepatic adenoma associated with, 787 - hepatic angiosarcoma associated with, 839 Stomach, 236–307 - caustic gastroduodenal injury, 258 - CT findings amyloidosis, 27 HIV/AIDS, 9 - differential diagnosis, 237–238 epigastric pain, 238 gastric antral narrowing, 237 gastric dilation or outlet obstruction, 237–238 gastric mass lesions, 237 gastric ulceration (without mass), 237 intramural mass, 237 intrathoracic stomach, 237 left upper quadrant mass, 238 linitis plastica, limited distensibility, 238 "target" or bull's eye lesions, 237 thickened gastric folds, 237 - fundoplication complications, 274–279 esophageal motility disturbances vs., 185 esophageal scleroderma vs., 189 - gastric bezoar, 260–261 complication of partial gastrectomy, 271 differential diagnosis, 261 - gastric diverticulum, 242–243 - gastric neoplasms. See Gastric neoplasms, benign; Gastric neoplasms, malignant. - gastric ulcer. See Gastric ulcer. - gastric volvulus, 262–267 - gastritis. See Gastritis. - gastroparesis, 259 - iatrogenic injury: feeding tubes, 268–269 caustic esophagitis vs., 173 imaging, 269 - imaging approach, 236–241 anatomical considerations, 236 anatomy (graphic images), 239 differential diagnosis, 237–238 gastric anatomy and terminology, 236 image gallery, 240–2241 imaging issues, 236 mural anatomy, 236 thick-walled stomach, 236–237 - imaging of bariatric surgery, 280–285 - intrathoracic stomach, differential diagnosis, 237 - Ménétrier disease, 256–257 differential diagnosis, 257 gastric carcinoma vs., 300 - neoplasms. See Gastric neoplasms, benign; Gastric neoplasms, malignant. - partial gastrectomy: Bilroth procedures, 270–273 - Zollinger-Ellison syndrome. See Zollinger-Ellison syndrome. Storage diseases. See also Glycogen storage disease. - splenomegaly and hypersplenism associated with, 559, 560 Streaming artifact, portal vein occlusion vs., 702 Stress, gastric ulcer associated with, 250

INDEX Stress-induced sympathetic reflexes, ileus associated with, 387 Stromal ulceration, complication of partial gastrectomy, 271–272 Strongyloidiasis, toxic megacolon associated with, 471 Subclavian/IJ vein occlusion, superior vena cava obstruction vs., 37 Subclavian vein occlusion, superior vena cava obstruction vs., 37 Sulfuric acid, caustic esophagitis associated with, 173 Superficial spreading carcinoma, Candida esophagitis vs., 163 Superior mesenteric artery occlusion, omental infarct associated with, 90 Superior mesenteric artery (SMA) syndrome, 324–325 - differential diagnosis, 325 - intestinal scleroderma vs., 377 - predisposing conditions, 325 Superior vena cava compression, superior vena cava obstruction associated with, 37 Superior vena cava obstruction, 36–37 - differential diagnosis, 37 - portal hypertension and varices vs., 116 Suppurative cholangitis. See Ascending cholangitis. Surgery - enteric fistulas and sinus tracts associated with, 407 - hepatic infarction associated with, 719 - splenic infection and abscess associated with, 556 Susceptibility artifacts, biliary, 864 Systemic hypotension, 34–35 - differential diagnosis, 35 - ischemic enteritis vs., 413 - mesenteric and small bowel trauma vs., 417 Systemic lupus erythematosus - esophageal scleroderma associated with, 190 - intestinal scleroderma associated with, 378 - lupus vasculitis, 39, 40 Systemic mastocytosis, 369 - differential diagnosis, 369 - duodenal ulcer associated with, 320 - gastric ulcer associated with, 250 Systemic nodular panniculitis. See Sclerosing mesenteritis.

T

Takayasu arteritis. See also Vasculitis. - definition, 39 - imaging findings, 39 Tannin, gastric bezoar associated with, 261 Telangiectasias of skin, intramural benign gastric tumors associated with, 291 Teratoma, metastatic: hepatic angiomyolipoma and lipoma vs., 799 Terminal ileitis. See Crohn disease. Testicles, ultrasonographic findings in leukemia and lymphoma, 56 TGF-b1RII gene deletion, colon carcinoma associated with, 526

THADs. See Transient hepatic attenuation or intensity difference (THADs and THIDs). Thiamine deficiency, Chagas disease of esophagus vs., 165 THIDs. See Transient hepatic attenuation or intensity difference (THADs and THIDs). Thoracic mass - Bochdalek hernia vs., 112 - Morgagni hernia vs., 113 Thoracic trauma, traumatic diaphragmatic rupture associated with, 122 Thorax, CT findings in sarcoidosis, 29 Thorotrast - hepatic angiosarcoma associated with, 839 - hepatocellular carcinoma associated with, 808 Thromboembolism, splenic infarction associated with, 564 Thrombosed esophageal varices, inflammatory polyp vs., 227 Thrombosis - Budd-Chiari syndrome associated with, 712 - complication of small intestine transplantation, 431 - hepatic artery, ischemic bile duct injury associated with, 944 - portal vein occlusion associated with, 702 - superior vena cava obstruction associated with, 37 Thrombotic events, ischemic enteritis associated with, 413 Thyroiditis - primary biliary cirrhosis associated with, 654 - primary sclerosing cholangitis associated with, 936 Tobacco. See Smoking. Torsion of appendages, epiploic appendagitis associated with, 500 Toxic megacolon, 470–473 - cecal volvulus vs., 507 - colonic ileus and Ogilvie syndrome vs., 509–510 - differential diagnosis, 471 - image gallery, 470, 472–473 - sigmoid volvulus vs., 503 TP53 gene, small bowel carcinoma associated with, 443 Tracheobronchial aspiration, esophageal perforation vs., 213 Traction diverticulum, 208 - differential diagnosis, 208 - pulsion diverticulum vs., 209 Transient hepatic attenuation or intensity difference (THADs and THIDs), 690–695 - associated abnormalities, 692 - differential diagnosis, 691 - image gallery, 690, 693–695 - other causes, postoperative changes of liver vs., 746 Transjugular intrahepatic portosystemic shunt, 748–753 - differential diagnosis, 750 - image gallery, 748, 751–753 - staging, grading, & classification, 750 Transmesenteric postoperative hernia, 108–111 - differential diagnosis, 109 - image gallery, 108, 111 - paraduodenal hernia vs., 105 - staging, grading, & classification, 110 Transplantation - hepatic infarction associated with, 719 li

INDEX - hepatic TB and fungal infections associated with, 605 - nodular regenerative hyperplasia associated with, 664 - pancreatic, 1022–1025 - small intestine, 430–433 Trauma - abdominal, sclerosing mesenteritis associated with, 82 - abdominal wall hernia, traumatic, 118–119 - ascites associated with, 86 - barotrauma, 48–49 differential diagnosis, 49 pneumatosis of intestine vs., 395 - biliary trauma, 946–949 - Boerhaave syndrome, 216–217 differential diagnosis, 217 esophageal perforation vs., 213 - colonic ileus and Ogilvie syndrome associated with, 510 - colorectal trauma, 514–515 - desmoid neoplasms associated with, 38 - diaphragmatic rupture, traumatic, 120–123 - duodenal, pancreatic trauma associated with, 1016 - esophageal perforation. See Esophageal perforation. - foreign bodies abdominal, 42–47 esophageal. See Esophageal foreign body. - gastroduodenal trauma, 326–327 differential diagnosis, 327 duodenal carcinoma vs., 335 - hepatic. See Hepatic trauma. - intestinal trauma, intestinal (angioneurotic) angioedema vs., 381 - intrahepatic arteriovenous fistula, traumatic: hereditary hemorrhagic telangiectasia vs., 727 - mesenteric and small bowel trauma, 416–421 differential diagnosis, 416 hepatic trauma associated with, 738 systemic hypotension vs., 35 - omental infarct associated with, 90 - operative, colonic ileus and Ogilvie syndrome associated with, 510 - pancreatic, 1014–1017 chronic pancreatitis associated with, 1002 differential diagnosis, 1015 systemic hypotension vs., 35 - paraduodenal hernia associated with, 106 - post-traumatic pancreatic atrophy, agenesis of dorsal pancreas vs., 980 - rectal carcinoma vs., 531 - sclerosing mesenteritis associated with, 82 - spleen. See Splenic trauma. Traumatic abdominal wall hernia, 118–119 Traumatic diaphragmatic rupture, 120–123 - associated abnormalities, 122 - differential diagnosis, 121–122 - image gallery, 120, 123 Traumatic intrahepatic arteriovenous fistula, hereditary hemorrhagic telangiectasia vs., 727 Trichobezoar, 261 Tricuspid valve disease, passive hepatic congestion associated with, 707 Trisomy 18, umbilical hernia associated with, 103 lii

Tropical pancreatitis, chronic pancreatitis associated with, 1002 True pancreatic cyst. See Nonneoplastic pancreatic cysts. Tuberculosis, 12–15 - differential diagnosis, 14 - hepatic TB and fungal infections, 604–607 - image gallery, 12, 15 - infectious lymphadenopathy from, superior vena cava obstruction associated with, 37 - intestinal, duodenal carcinoma vs., 335 - radiologic findings, 13–14 Tuberculous gastritis, 245 Tuberculous peritonitis - abdominal mesothelioma vs., 141 - peritoneal metastases vs., 146 - pseudomyxoma peritonei vs., 149–150 - radiologic findings, 13 Tuberous sclerosis - congenital hepatic fibrosis associated with, 592 - hepatic cyst associated with, 766 Tubular adenomatous polyps, colonic, 517 Tubulovillous adenomatous polyps, colonic, 517 Tumefactive sludge, gallbladder polyps vs., 953 Tumor implantation in abdominal incision sites, 128 Turcot syndrome, colonic polyps associated with, 518 Typhlitis. See Neutropenic colitis (typhlitis). Typhoid fever, toxic megacolon associated with, 471 Tyrosine kinase activity, gastric GIST associated with, 296 Tyrosine kinase growth factor receptor, intestinal GIST associated with, 449

U

Ulcerative colitis, 466–469 - associated abnormalities, 468 - colon carcinoma vs., 525 - Crohn disease vs., 371 - differential diagnosis, 467–468 - epiploic appendagitis vs., 499–500 - gallbladder carcinoma associated with, 958 - genetics, 468 - image gallery, 466, 469 - infectious colitis vs., 459 - intestinal parasites and infestation vs., 359 - ischemic colitis vs., 475–476 - primary sclerosing cholangitis associated with, 936 Ultraviolet radiation, metastatic melanoma associated with, 60 Umbilical hernia, 103 - differential diagnosis, 103 - spigelian hernia vs., 101 Undifferentiated sarcoma, hepatic, 842–843 Ureteral colic, duodenitis vs., 317 Ureteral tuberculosis, radiologic findings, 13 Uveitis - Crohn disease associated with, 372 - ulcerative colitis associated with, 468

INDEX

V

Vagal nerve degenerative changes, esophageal achalasia associated with, 182 Vaginal atresia, congenital hepatic fibrosis associated with, 592 Vagotomy - complication, esophageal scleroderma vs., 189 - gastric bezoar associated with, 261 Variants, biliary. See Biliary normal variants and artifacts. Varices. See Esophageal varices; Portal hypertension and varices. Vascular congestion, omental infarct associated with, 90 Vascular injuries, pancreatic trauma associated with, 1016 Vascular occlusion, ischemic enteritis associated with, 413 Vasculitis, 38–41 - hepatic infarction associated with, 719 - image gallery, 38, 41 - intestinal (angioneurotic) angioedema vs., 381 - lupus vasculitis, 39, 40 - small intestine. See Small intestine vasculitis. - staging, grading, & classification, 40 Vena cava - inferior. See Inferior vena cava. - superior. See Superior vena cava obstruction. Venoocclusive disease, hepatic, 716–717 Venous thromboses - appendages, epiploic appendagitis associated with, 500 - complication of acute pancreatitis, 991 - Crohn disease associated with, 372 Ventral hernia, 100 - spigelian hernia vs., 101 - umbilical hernia vs., 103 Vicarious excretion (of contrast medium), 153 - differential diagnosis, 153 - milk of calcium bile vs., 929 Vigorous activity, omental infarct associated with, 90 Villous adenoma, colon, 520–523 - differential diagnosis, 521–522 - duodenal metastases and lymphoma vs., 339 - fecal impaction and stercoral ulceration vs., 512 - gastroduodenal trauma vs., 327 - image gallery, 520, 523 - rectal, rectal carcinoma vs., 531 Villous adenomatous polyps, colonic, 517 Villous tumor. See Villous adenoma, colon. Viral esophagitis, 164 - Barrett esophagus vs., 171 - Candida esophagitis vs., 163 - differential diagnosis, 164 - drug-induced esophagitis vs., 174 - reflux esophagitis vs., 167 Viral hepatitis, 620–625 - acute, passive hepatic congestion vs., 707 - alcoholic liver disease vs., 627 - autoimmune hepatitis vs., 631 - chronic, hepatocellular carcinoma associated with, 808 - differential diagnosis, 621–622 - hepatic injury from toxins vs., 639

- hepatomegaly associated with, 689 - image gallery, 620, 623–625 - steatosis and steatohepatitis vs., 634 Viral infections - cytomegalovirus infection intestinal, 361, 362 post-transplant lymphoproliferative disorder associated with, 52 - duodenitis associated with, 317 - herpesvirus infection, Candida esophagitis associated with, 163 - infectious colitis associated with, 460 - meseneric adenitis and enteritis associated with, 357 Visceral malignancy - primary, sclerosing mesenteritis vs., 82 - splenosis vs., 571 Visceral mass - accessory spleen vs., 549 - splenosis vs., 571 Vitelline duct abnormalities, Meckel diverticulum associated with, 354 Volvulus - cecal, 506–507 colonic ileus and Ogilvie syndrome vs., 509 differential diagnosis, 507 - gastric, 262–267 - sigmoid. See Sigmoid volvulus. Vomiting, Boerhaave syndrome associated with, 217 von Hippel-Lindau syndrome, nonneoplastic pancreatic cysts associated with, 1032 von Recklinghausen disease, gastric GIST associated with, 296

W

Waldenström macroglobulinemia - amyloidosis associated with, 27 - celiac-sprue disease vs., 366 Wandering spleen, gastric volvulus associated with, 264 Wegener granulomatosis. See also Vasculitis. - definition, 39 - imaging findings, 39 Weight loss, SMA (superior mesenteric artery) syndrome associated with, 325 Weightlifting, Boerhaave syndrome associated with, 217 Whipple disease, 368 - celiac-sprue disease vs., 365 - differential diagnosis, 368 - intestinal lymphangiectasia vs., 385 - intestinal metastases and lymphoma vs., 446 Whipple procedure - normal findings after, 1019 - postoperative imaging, 1019 Wilson disease, 684–687 - differential diagnosis, 685 - genetics, 685 - hepatomegaly associated with, 689 - image gallery, 684, 686–687

liii

INDEX

X

Xanthogranulomatous cholecystitis, 910–913 - differential diagnosis, 911–912 - gallbladder carcinoma vs., 957 - hyperplastic cholecystoses vs., 924 - image gallery, 910, 913 - staging, grading, & classification, 912 Xanthogranulomatous mesenteritis. See Sclerosing mesenteritis.

Z

Zenker diverticulum, 202–205 - differential diagnosis, 203–204 - image gallery, 202, 205 - traction diverticulum vs., 208 Zollinger-Ellison syndrome, 252–255 - differential diagnosis, 253–254 - duodenal carcinoma vs., 335 - duodenal ulcer associated with, 320 - gastric ulcer associated with, 250 - gastritis vs., 243–244 - image gallery, 252, 255 - mastocytosis vs., 369 - Ménétrier disease vs., 257

liv