Essentials in Hematology and Clinical Pathology [2 ed.] 9741283608, 9789351524236

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Essentials in HEMATOLOGY AND CLINICAL PATHOLOGY

Essentials in HEMATOLOGY AND CLINICAL PATHOLOGY Second Edition

Ramadas Nayak

MBBS MD

Professor and Head Department of Pathology Yenepoya Medical College Yenepoya University Mangaluru, Karnataka, India Formerly, Head Department of Pathology Kasturba Medical College Manipal University Mangaluru, Karnataka, India

Sharada Rai

MBBS MD

Associate Professor Department of Pathology Kasturba Medical College Manipal University Mangaluru, Karnataka, India

Foreword K Ramnarayan

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Jaypee Brothers Medical Publishers (P) Ltd Bhotahity, Kathmandu, Nepal Phone: +977-9741283608 Email: [email protected] Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2017, Jaypee Brothers Medical Publishers The views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and do not necessarily represent those of editor(s) of the book. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of the publishers. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Medical knowledge and practice change constantly. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contraindications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/ or damage to persons or property arising from or related to use of material in this book. This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought. Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity.

Inquiries for bulk sales may be solicited at: [email protected] Essentials in Hematology and Clinical Pathology First Edition: 2012 Second Edition:  2017 ISBN 978-93-5152-423-6 Printed at

Dedicated to Students who inspired us, patients who provided the knowledge, our parents and family members who encouraged and supported us.

Foreword

“Some books are to be tasted, others swallowed and some few to be chewed and digested,” said Francis Bacon. This book, for which I am delighted to write the Foreword, has to be not merely tasted, chewed, swallowed and digested but also absorbed and assimilated for best results! Clarifying concepts and inculcating the foundational tenets in hematology and clinical pathology are daunting tasks for any teacher. The teachers who have authored this book have admirably captured the core of the subject capping that with lucid explanations. The authors have expertize not only in the subject but also in the art of teaching. Willingness to share and the ability to convey convincingly are the veritable attributes of the authors. It is this wisdom of experience and expression that has percolated into this book. A book of this substance and style was long overdue and it could not have been timelier. I am certain that the contents of the book will mellow with each succeeding edition in the years to come. Let me congratulate and commend the authors for the pains they took to bring out a book, which deserves much more than just having a look.

K Ramnarayan MBBS MD (Path) PG Dip. Higher Education

Vice-Chancellor Manipal University Manipal, Karnataka, India

Preface to the Second Edition Hematology is one of the rapidly expanding fields of medicine with new techniques. An extensive amount of time and effort is spent by the students in going through large volumes of various hematology textbooks. Hence, this second edition is a comprehensive book that has retained the total number of pages same as in the first edition and has also included updates on recent changes in hematology. Chapter 49 is renamed as “Automation in Hematology” and principles and uses of automations have been dealt with. A new Chapter 67 “Clinical Scenario” is added to help the student to solve the clinical-oriented questions asked in a few university examinations. New appendix 2 with laboratory values of clinical importance is also added. Understanding hematology requires insight into the applied physiology and the pathophysiologic basis of these diseases in the context of relevant clinical features which is often neglected. Essentials in Hematology and Clinical Pathology emphasizes on building a strong foundation of both concepts. Clinical pathology section of the book deals with both hematological and nonhematological laboratory investigations done in routine practice. The book has been organized into four sections namely Disorders of Red Cells, Disorders of White Cells, Disorders of Hemostasis and Clinical Pathology. Essentials in Hematology and Clinical Pathology also features: •• Molecular basis of common hematological disorders •• About 135 illustrations, 27 photomicrographs, 18 photographs and 146 tables have been provided to facilitate easy and quick learning. Some of the illustrations and photomicrographs have been improved in quality •• A summary of the important points at the end of each chapter •• Essay questions, short note questions and more than 300 multiple choice questions (MCQs) to encourage self-evaluation of the important concepts by the students •• Recent WHO classification (2016) of Tumors of Hematopoietic and Lymphoid Tissues We hope that the textbook will provide a foundation to the students in hematology and clinical pathology and improve their understanding of the subject.

Ramadas Nayak Sharada Rai

Preface to the First Edition Hematology is one of the rapidly expanding fields of medicine. The extensive amount of time and effort spent by the students in going through volumes of the hematology textbooks encouraged us to write this comprehensive book. Understanding hematology requires insight into the applied physiology and the pathophysiologic basis of these diseases in the context of relevant clinical features which is often neglected. Essentials in Hematology and Clinical Pathology emphasizes on building a strong foundation of both concepts. Clinical pathology section of the book deals with both hematological and nonhematological laboratory investigations done in routine practice. The book has been organized into four sections namely Disorders of Red Cells, Disorders of White Cells, Disorders of Hemostasis and Clinical Pathology. Essentials in Hematology and Clinical Pathology also features: •• Molecular basis of common hematological disorders •• About 135 illustrations, 27 photomicrographs, 18 photographs and 146 tables have been provided to facilitate easy and quick learning •• A summary of the important points at the end of each chapter •• Essay questions, short note questions and 351 MCQs to encourage self-evaluation of the important concepts by the students •• Recent WHO classification (2008) of Tumors of Hematopoietic and Lymphoid Tissues. We hope that the textbook will provide a foundation to the students in hematology and clinical pathology and improve their understanding of the subject.

Ramadas Nayak Sharada Rai Astha Gupta

Acknowledgements First and foremost, we wish to express our respects and deep gratitude to Dr Astha Gupta, for having been the author for the first edition of this book. Our sincere thanks to Ms Prathibha Bhat, for her untiring efforts, patience and excellent support in creating the illustrations for the first edition of this book. •• We wish to express our gratitude to Mr Yenepoya Abdulla Kunhi, Honorable Chancellor, and Mr Farhaad Yenepoya, Director of Finance, Yenepoya University (Accredited by NAAC with “A” grade), Mangaluru, Karnataka, India, for their inspiration and encouragement. •• We are grateful to Dr K Ramnarayan, former Vice-Chancellor, Manipal University, Manipal, Karnataka, for writing the foreword for the first edition, and encouragement and support. •• We also wish to thank all our family members including Smt Rekha Nayak, Ms Rashmitha Nayak, Mr Ramnath Kini, Master Rishab Kini, Mr Ravidas Nayak (Engineer, Bengaluru), Dr Narendra Shetty, Master Jagrath, who have patiently accepted our long preoccupation with this work. Our sincere gratitude to our parents who will always remain our guiding light. We would like to express our gratitude to all our friends, undergraduate and postgraduate students (Department of Pathology, Yenepoya Medical College, Mangaluru) and colleagues, who helped, inspired and supported us in the different stages of preparing the manuscript; to all those who provided support, talked things over, read, offered comments and assisted in the editing, proofreading and design. •• Dr Rakshatha Nayak, Tutor, Department of Pathology, Yenepoya Medical College, a constituent of Yenepoya University (Accredited by NAAC with “A” grade), Mangaluru. •• We are thankful to all our friends Dr Krishnaraj Upadhyaya (Professor), and Dr Krishna Prasad HV (Assistant Professor), Department of Pathology, Yenepoya Medical College, a constituent of Yenopoya University (Accredited by NAAC with “A” grade), Mangaluru. •• A special thanks to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Group President), Mr Tarun Duneja (Director–Publishing), and Ms Chetna Malhotra Vohra (Associate Director–Content Strategy) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, for publishing the book in the same format as wanted, well in time. We are grateful to Shri Jitendar P Vij, for unmasking our talent as authors. •• We would like to offer a huge appreciation to the wonderful work done by Ms Sunita Katla (Publishing Manager), Ms Samina Khan (Executive Assistant to Director–Publishing), Mr Rajesh Sharma (Production Coordinator), Ms Seema Dogra (Cover Designer), Mr Laxmidhar Padhiary (Proofreader), Mr Rajesh Ghurkundi (Graphic Designer) and Mr Raj Kumar (DTP Operator) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India. •• We thank especially Mr Venugopal V (Bengaluru) and Mr Vasudev H (Mangaluru) of M/s Jaypee Brothers Medical Publishers (P) Ltd, Bengaluru Branch, Karnataka, for taking this book to every corner of Karnataka. •• Last but definitely not least, a thank you to our undergraduate and postgraduate students. Without you, we would not write. You make all our books possible. There are many more people we could thank, but space, and modesty compel us to stop here.

Contents SECTION 1

Disorders of Red Cells 1. Introduction

Definition 3 Hematopoiesis 4

2. Classification of Anemia

57

b-Thalassemia 58 a-Thalassemia 66

8. Sickle Cell Disease

51

Hereditary spherocytosis  52 Hereditary elliptocytosis  55

7. Thalassemia Syndromes

41

Hemolytic anemia  43 Classification of hemolytic anemias  49

6. Hemolytic Anemias due to Red Cell Membrane Disorders

24

Metabolism of vitamin B12 and folic acid  25 Etiology of megaloblastic anemia  28 Laboratory findings of megaloblastic anemia  29 Anemias of vitamin B12 deficiency  33 Anemia of folate deficiency  38 Nonmegaloblastic causes of macrocytic anemias  39

5. Introduction and Classification of Hemolytic Anemia

14

Iron metabolism  14 Iron deficiency anemia  17

4. Megaloblastic Anemia

9

Red cell  9 Anemia 10

3. Iron Deficiency Anemia

3

Sickle cell anemia  70 Sickle cell trait  78 Other sickling syndromes  79 Other hemoglobinopathies  80

69

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Essentials in Hematology and Clinical Pathology

9. Hemolytic Anemias due to Red Cell Enzyme Deficiencies

Metabolic pathways in red blood cells  83 Glucose-6-phosphate dehydrogenase deficiency  84 Pyruvate kinase deficiency  87

10. Immunohemolytic Anemia

117

Hereditary sideroblastic anemias  118 Acquired idiopathic sideroblastic anemia  119 Congenital dyserythropoietic anemias  119

17. Approach to Anemias

112

Anemia of chronic disease  112 Anemia of renal disease  114 Anemia of liver disease  114 Anemias of blood loss  114 Anemia associated with marrow infiltration (myelophthisic anemia)  115

16. Sideroblastic Anemia

110

Definition 110 Etiology 110 Clinical features  110 Laboratory findings  111

15. Miscellaneous RBC Disorders

104

Definition 104 Etiology 104 Pathogenesis 105 Clinical features  106 Laboratory findings  107

14. Pure Red Cell Aplasia

100

Definition 100 Etiology and pathogenesis  100 Clinical features  101 Laboratory findings  102

13. Aplastic Anemia

98

Classification 98 Laboratory findings  99

12. Paroxysmal Nocturnal Hemoglobinuria

89

Alloimmune hemolytic anemia  89 Autoimmune hemolytic anemia  92

11. Fragmentation Syndrome

83

Approach to the diagnosis of anemia  121 Approach to the diagnosis of hemolytic anemia  125

121

Contents

SECTION 2

Disorders of White Cells 18. Quantitative and Qualitative Disorders of White Blood Cells

Classification of WBC disorders  131 Quantitative disorders of leukocytes  132 Qualitative disorders of leukocytes  138

19. Infectious Mononucleosis

182

Chronic myelogenous leukemia  182 Myelodysplastic/myeloproliferative neoplasms  189

26. Polycythemia

176

Essential thrombocythemia  177 Primary myelofibrosis  178

25. Chronic Myelogenous Leukemia and Other Myeloid Neoplasms

170

Definition 170 Classification 170 Etiology and molecular pathogenesis  172 Clinical features  173 Laboratory findings  173

24. Myeloproliferative Neoplasm

164

Acute myelogenous leukemia  164 Myeloid sarcoma  167

23. Myelodysplastic Syndromes

158

Acute lymphoblastic leukemia  158 Acute lymphoblastic lymphoma  162

22. Acute Myelogenous Leukemia and Related Neoplasm

147

Neoplastic proliferations of white cells  147 Acute leukemia  148

21. Acute Lymphoblastic Leukemia

141

Definition 141 Pathogenesis 141 Clinical features  143 Laboratory findings  144 Lesions associated with EBV infection  146

20. Introduction to Acute Leukemia

129

Polycythemia vera  193

192

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Essentials in Hematology and Clinical Pathology

27. Chronic Lymphocytic Leukemia and Other Lymphoid Leukemias

197

Chronic lymphocytic leukemia  197 Prolymphocytic leukemia  201 Hairy cell leukemia  202

28. Plasma Cell Neoplasms

Multiple myeloma (plasma cell myeloma)  207 Plasmacytoma 215 Immunoglobulin deposition diseases  216 Monoclonal gammopathy of uncertain significance  216 Osteosclerotic myeloma  216

29. Lymphopoietic System

206

219

Lymph nodes  219 Development of lymphocytes (lymphopoiesis)  221

30. Lymphoid Neoplasms

226

Classification of lymphoid neoplasms  227 Precursor lymphoid neoplasms  228 Mature B cell neoplasms  228 Mature T cell and NK cell neoplasms  240

31. Hodgkin Lymphoma

247

Classical Hodgkin lymphoma  251 Nodular lymphocyte predominant Hodgkin lymphoma  256 Etiology and pathogenesis of Hodgkin lymphoma  258 Laboratory findings  259 Clinical features  260

32. Langerhans Cell Histiocytosis

264

Definition 264 Morphology 264 Laboratory findings  265

SECTION 3

Disorders of Hemostasis 33. Normal Hemostasis and its Components

Platelets 269 Blood vessel wall  270 Coagulation system  271 Coagulation regulatory mechanism  274 Fibrinolytic system  275 Normal hemostasis  276

269

Contents

34. Bleeding Disorders: Vessel Wall Abnormalities

280

Disorders of hemostasis  280 Bleeding disorders caused by vessel wall abnormalities  283

35. Bleeding Disorders: Abnormalities of Platelet

286

Quantitative platelet disorders  286 Qualitative platelet disorders  296

36. Bleeding Disorders: Abnormalities of Coagulation Factors

300

Hereditary deficiencies  301 Acquired coagulation disorders  306 Disseminated intravascular coagulation  307

37. Thrombotic Disorders: Hypercoagulable States

313

Inherited hypercoagulable states  314 Acquired hypercoagulable states  315

SECTION 4

Clinical Pathology 38. Anticoagulants and Collection of Blood

39. Hematopoiesis

329

Erythropoiesis 329 Myelopoiesis 331 Megakaryopoiesis 333

40. Hemoglobin Estimation

321

Anticoagulants 321 Steps in hematological investigation  323

335

Indications for hemoglobin estimation  335 Methods of hemoglobin estimation  335

41. Cell Count

343

Red blood cell count  345 Total WBC count  347 Platelet count  349 Absolute eosinophil count  351

42. Peripheral Blood Smear Examination

Stains for blood smear  354 Preparation of the peripheral blood smear  355 Fixation of the smear  356 Staining of the smear  356 Examination of a peripheral blood smear  357

354

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Essentials in Hematology and Clinical Pathology

43. Reticulocyte Count

Methods of reticulocyte count  366 Significance of reticulocyte count  368

44. Hematocrit, Red Cell Indices and ESR Estimation

418

Collection of urine specimen  418 Preservation of urine  419 Examination of urine  419 Physical examination  419 Chemical examination  424 Microscopic examination  439

51. Body Fluids

408

Automated hematology analyzer  408 Flow cytometry  415

50. Urine Analysis

394

Tests for platelet component  395 Tests for platelet and vascular component  396 Tests for coagulation component  398 Tests for fibrinolytic activity  402

49. Automation in Hematology

390

Definition 390 Myeloperoxidase 390 Sudan black B 391 Nonspecific esterase  391 Periodic acid-Schiff reaction  391 Neutrophil alkaline phosphatase  392

48. Laboratory Evaluation of Hemostatic and Thrombotic Disorders

387

Procedure 387 Interpretation 388

47. Cytochemistry in Leukemia

381

Bone marrow aspiration  381 Bone marrow trephine biopsy  384

46. Osmotic Fragility Test

370

Hematocrit 370 Red cell (erythrocyte) indices  373 Erythrocyte sedimentation rate  375 Lupus erythematosus cell test  378

45. Bone Marrow Examination

366

Examination of body fluids  447 Examination of synovial fluids  448

446

Contents

52. Cerebrospinal Fluid Examination

Importance of CSF examination  451 Collection of CSF 451 Examination of CSF 453

53. Semen Analysis

499

Blood transfusion  499 Blood components  503 Transfusion reactions  505 Exchange transfusion  508

61. Hematopoietic Stem Cell Transplantation

495

Direct antiglobulin test  495 Indirect antiglobulin test  497

60. Transfusion Medicine

487

ABO blood group system  487 Rh blood group system  492 Other blood group systems  493

59. Antiglobulin Test

484

Oral glucose tolerance test  484 Glycosuria 486

58. Blood Group System

474

Cytology of female genital tract  477 Cytology of other systems  480 Buccal smear for Barr body  480 FNAC appearance of some common lesions  481

57. Glucose Tolerance Test

470

Sputum collection  470 Examination of sputum  471

56. Cytology

466

Pregnancy tests  466

55. Sputum Examination

457

Different procedures of semen analysis  457 Cryopreservation of spermatozoa  462

54. Pregnancy Test

451

Definition 510 Sources of hematopoietic stem cells  510 Types of hematopoietic stem cell transplant  511 Indications for hematoporetic stem cell transplantation  511 Autologous stem cell transplant  511

510

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Essentials in Hematology and Clinical Pathology

Allogeneic stem cell transplantation  512 Complications of hematopoietic stem cell transplantation  513

62. Gastric Function Tests

Tests for gastric acid secretion  515 Other tests  516

63, Liver Function Tests and Liver Biopsy

538

Stool examination  539 Stool culture and sensitivity  545

67. Clinical Scenario

533

Thyroid function tests  534

66. Stool Examination

529

Tests for renal function  529 Renal biopsy  531

65. Thyroid Function Tests

518

Liver function tests  518 Liver biopsy  524

64. Renal Function Tests

515

546

Symptoms and signs that suggest a blood disease  546 Patterns strongly suggestive of a blood disease  547

Bibliography 555 Appendices 557

Appendix 1: WHO classification of tumors of hematopoietic and lymphoid tissues  557 Appendix 2: Laboratory values of clinical importance  562

Index 569

1

SECTION

Disorders of Red Cells

1. Introduction 2. Classification of Anemia 3. Iron Deficiency Anemia 4. Megaloblastic Anemia 5. Introduction and Classification of Hemolytic Anemia 6. Hemolytic Anemias due to Red Cell Membrane Disorders 7. Thalassemia Syndromes 8. Sickle Cell Disease 9. Hemolytic Anemias due to Red Cell Enzyme Deficiencies 10. Immunohemolytic Anemia 11. Fragmentation Syndrome 12. Paroxysmal Nocturnal Hemoglobinuria 13. Aplastic Anemia 14. Pure Red Cell Aplasia 15. Miscellaneous RBC Disorders 16. Sideroblastic Anemia 17. Approach to Anemias

1 CHAPTER Introduction

Chapter Outline

□

Definition

□

Hematopoiesis

DEFINITION Hematology is defined as the study of normal antl pathologic aspects of blood and blood cells. Hematopoiesis (hemopoiesis) is the continuous, regulated process of blood cell production or formation. Hematopoietic (hemopoietic) system: It consists of all organs and tissues involved in hematopoiesis, and these are divided into myeloid tissue and lym phoid tissue. The pluripotent hematopoietic stem cell (HSC) is the progenitor of all the cells in blood and gives rise to cells of both myeloid and lymphoid system. 1. The myeloid tissue consists o£bone marrow (medullary cavity) and the cells derived from it, which include: • Red blood cells (RBCs/erythrocytes) • White blood cells (WBCs/leukocytes, except lymphocytes): WBCs consist of: - Granulocytes.: Neutrophils, eosinophils and basophils are collectively called granulocytes because of their different types of cytoplasmic granules. However, the term granulocyte is often referred to only neutrophils. - Monocytes - Lymphocytes (even though included under WBCs; they are lymphoid derived). • Platelets (thrombocytes) Compensatory hyp erplasia: In adults during pathological states, whenever there is an increased demand for blood cells, the bone marrow undergoes compensatory hyp erplasia. This results in replacement of the fatty marrow by hematopoietic tissue. • Extramedullary hematopoiesis: - Normally, the cells of the myeloid lineage arise in the central bone marrow (medullary cavity). If the increased demand of blood cells is not met with compensatory hyp eractivity of marrow alone, hematopoietic islands appear in liver and spleen (resulting in hepatosplenomegaly) and even in lymph nodes.

4

SECTION 1  Disorders of Red Cells –– The myeloid lineage blood cells arising outside the marrow elsewhere in the body are designated as extramedullary hematopoiesis (agnogenic myeloid metaplasia). 2. The lymphoid tissue consists of thymus, lymph nodes and spleen. The common lymphoid progenitor cell gives rise to B cell, T cell and natural killer (NK) cell precursors. They mature to form respective lymphoid cells. The above division of hematopoietic elements as myeloid and lymphoid tissue is mainly for understanding their pathology. It is not always possible to draw clear demarcation between the diseases affecting them.

Functions of Blood Cells

Table 1.1: Main functions of formed elements of blood

Formed elements of blood are red cells, Type of blood cell Main function white cells and platelets. The main Red blood cells Delivery of oxygen to functions of blood cells are presented in tissues Table 1.1. White blood cells Defence against infectious •• As the mature blood elements become organisms old, they are destroyed and constantly Lymphocytes Immune regulation produced to maintain normal periphPlatelets Hemostasis eral blood cell counts. •• In addition, each cell line has the ability to respond appropriately to increased demand like; increased red cell production after blood loss, leukocytosis during infection, wound healing and increased platelet production during chronic bleeding. •• Despite the wide functional diversity of blood cells, all myeloid and lymphoid cells originate from common precursor; pluripotent hematopoietic stem cells (HSC).

HEMATOPOIESIS Sites of Hematopoiesis

Table 1.2: Different sites of hematopoiesis during various phases of life Phase

Period

Site

Yolksac (mesoblastic) phase

First 3 months of gestation

Yolk sac

Terminology Used in Hematopoiesis

Hepatic phase

4–9 months of gestation

Liver (chief site till birth), spleen (minor site)

The meaning of the terms used with reference to hematopoiesis is shown in Table 1.3.

Medullary (myeloid) phase

By 3rd week after birth up to

Bone marrow throughout the skeleton

Adults

Active marrow is limited to the ends of long bones and flat bones

Different sites of hematopoiesis during various phases of life are shown in Table 1.2.

Normal Development of Blood Cells (Hematopoiesis)

puberty

The hematopoietic system is a hierarchy of cells in which pluripotent hematopoietic stem cells proliferate and differentiate. After several steps, HSCs finally give rise to mature blood cells. This hierarchy (Figs 1.1 and 1.2) consists of: 1. Hematopoietic stem cells

CHAPTER 1  Introduction Table 1.3: Different terminologies used with regards to hematopoiesis Terminology Pluripotent

Ability to generate all mature hematopoietic cells

Multipotent

Ability to produce a limited range of differentiated cell lineages appropriate to their location

Unipotent

Restricted ability to differentiate and generate one specific cell type

2. Progenitor cells a. Multipotent progenitor cells b. Committed (unipotent) progenitor cells 3. Precursor cells 4. Maturing and mature cells.

Hematopoietic Stem Cells (HSC) These are small, undifferentiated mononuclear cells that can generate all the blood cell lineages. HSCs possess two fundamental properties: •• Self-renewal: HSCs are capable of cell division to give rise to more stem cells. Fig. 1.1: Cell hierarchy in hematopoiesis •• Differentiation: HSCs can differentiate and give rise to two kinds of lineage-specific multipotent progenitor cells, the common myeloid and the Box 1.1: Stem cell disorders common lymphoid progenitors. •• Chronic myeloid leukemia Note: Apart from blood cells, the stem cells may be •• Polycythemia vera able to differentiate into diverse tissue types (e.g. •• Essential thrombocythemia neuronal, muscle, liver, vascular cells). This change •• Aplastc anemia •• Paroxysmal nocturnal hemoglobinuria in the differentiation of a cell from one type to another is known as transdifferentiation, and the capacity of a cell to transdifferentiate into diverse lineages is referred to as developmental plasticity. Stem cell disorders (Box 1.1).

Progenitor Cells Upon commitment to development, the HSCs enter the next compartment known as progenitor cell compartment. This compartment consists of mainly two types of cells. •• Multipotent progenitor (lineage specific) cells •• Committed (unipotent) progenitor cells Both multipotent and unipotent cells in the bone marrow possess the ability to give rise to clones (groups) composed of specific kinds of mature cells when grown in culture and are called as colony forming units (CFU). Multipotent progenitor cells: These are of two types namely: Early progenitor with myeloid potential and early progenitor with lymphoid potential. •• Early progenitor with myeloid potential further divide to produce mainly two types of multipotent progenitor cells with restricted differentiation. They are:

5

6

SECTION 1  Disorders of Red Cells

Fig. 1.2: Different stages of hematopoiesis (Abbreviations: BFU, burst forming unit; CFU, colony forming unit)

–– CFU b/Mg/E (multipotent) cells which give rise to three types of committed (unipotent) progenitor cells. ◆◆ CFU-E (colony-forming unit-erythrocyte) cells. It is most sensitive to the action of erythropoietin.

CHAPTER 1  Introduction ◆◆ CFU-Mg (colony-forming unit-megakaryocyte) cells ◆◆ CFU-Baso (colony-forming unit-basophil) cells –– CFU-Mix which differentiate into three types of committed (unipotent) progenitor cells. ◆◆ CFU-G (colony-forming unit-granulocyte) cells, precursors of neutrophils ◆◆ CFU-M (colony-forming unit-macrophage) cells, precursors of monocytes and macrophages. ◆◆ CFU-Eo (colony-forming unit-eosinophil) cells, precursors of eosinophils. •• Early progenitor with lymphoid potential cell in turn gives rise to three progenitor cells. –– Pro-T cells which differentiate into T cells. –– Pro-NK cells which differentiate into NK cells. –– Pro-B cells which differentiate into B cells. Lymphocyte development is discussed in Chapter 29. Morphologically, the progenitor (both multipotent and unipotent) cells and stem cells cannot be distinguished from one another on morphological appearance or cytochemistry except by immunological techniques.

Precursor Cells When the immature hematopoietic cell acquires recognizable morphological, cytochemical or immunological feature of a single lineage, it is called as precursor cell. The next step in hematopoiesis is maturation of unipotent progenitor cells to precursor cells. The earliest morphologically recognizable precursor cell of each lineage is termed by adding the suffix “blast” to the type of lineage (e.g. lymphoblast to lymphoid lineage).

Mature Cells The precursor cells finally give rise to mature blood cells, which are released from the marrow into the circulation.

Regulation of Hematopoiesis The growth of different hematopoietic cells is regulated by a number of hematopoietic growth factors, which in general are called cytokines. Most important growth factors acting on various cells are mentioned below. •• Stem cells: Stem cell factor (also called c-KIT ligand), IL-6 and FLT3-ligand. •• CMP progenitor cells: –– Multipotent committed progenitors ◆◆ Granulocyte-macrophage colony-stimulating factor (GM-CSF) ◆◆ Thrombopoietin ◆◆ IL-3, IL-5, IL-6 and IL-11 –– Committed progenitors ◆◆ Erythropoietin (EPO): It is a glycosylated protein synthesized mainly by kidney and minor part from liver. It is produced in response to hypoxia. EPO acts on the erythroid precursors through EPO receptors. This stimulates proerythroblasts to proliferate and differentiate to produce RBCs.

7

8

SECTION 1  Disorders of Red Cells ◆◆ Granulocyte colony-stimulating factor (G-CSF) ◆◆ Thrombopoietin •• Lymphopoiesis is regulated by several interleukins (most important being IL-1, 2, 4, 5, 6, 7, 9). Components of bone marrow are listed in Box 1.2. The characteristic morphologic appearances of various cells of hematopoiesis are discussed in Chapter 39.

Box 1.2: Contents of bone marrow •• Hematopoietic cells –– Myeloid series –– Erythroid series –– Megakaryocytes –– Other cells: Lymphocytes, plasma cells •• Fat tissue •• Vessels •• Nerves •• Reticuloendothelial cells •• Stroma

SUMMARY •• Hematopoiesis is the continuous, regulated process of production of all blood cells. •• Organs and tissues involved in hematopoiesis are known as hematopoietic organs and are divided into myeloid and lymphoid tissue. •• The hematopoietic system is a hierarchy of cells and consists of HSC, multipotent and unipotent progenitors, morphologically identifiable precursors (blast cells) and mature cells. •• Bone marrow is the main site of hematopoiesis after birth and throughout life. •• Under abnormal conditions blood cells may be produced outside the marrow and such production is known as extramedullary hematopoiesis.

SELF-ASSESSMENT EXERCISES I. Short Notes 1. Extramedullary hematopoiesis. 2. Hematopoietic stem cell (HSC). 3. Erythropoietin. 4. Components/contents of bone marrow.

II. Multiple Choice Questions 1. In adults, erythropoiesis occurs mainly in: A. Small bones of hand and feet B. Flat and long bones C. Spleen and lung D. Kidneys and adrenals 2. The cell which has the capacity for self-renewal and pluripotent differentiation is: A. Hematopoietic stem cell B. Progenitor cell C. Precursor cell D. Mature cell 3. The commonest sites of extramedullary hematopoiesis in adult are: A. Liver and spleen B. Kidney and thymus C. Liver and yolk sac D. Lymph node and thymus 4. In the adult, the extramedullary hematopoiesis results in: A. Splenomegaly B. Hyposplenism C. Atrophy of liver D. Atrophy of lymphnodes

Answers 1. B 2. A 3. A 4. A

2

CHAPTER

Classification of Anemia

Chapter Outline

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Red Cell

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Anemia

RED CELL Mature red cell is a circular, biconcave disc-containing pigmented protein called hemoglobin and is bound by the cell membrane. On a peripheral blootl smear, they appear as pale red cells with central one-third pallor (where the upper an . lower membrane surfaces closely meet). The advantages of the characteristic morphology of the RBCs are: • The young, healthy red cells are quite flemble and highly deformable so that they can easily pass through extremely narrow capillary beds and splenic sinusoids. They rapidly regain their normal shape after exiting from the capillary bed. • Provides greater surface area compared to volume which allows considerable alterations in the cell volume. Thus the)) can resist hemolysis to certain extent. Aged RBCs become morn-rigid and less deformable and are removed from the circulation in the spleen.

Normal Parameter of Red Cell (Table 2.1) • Size: The size of normal RBCs ranges from 6.7 to 7.7 µm in diameter. • Life span: The average life span of normal RBC is 110-120 days. • Red cell indices (Table 2.1 and for details refer Chapter 44) - Mean cell (corpuscular) volume (MCV): It is the average volume of a red cell and expressed in femtoliters (fL). - Mean cell (corpuscular) hemoglobin (MCH): It represents the average content (mass) of hemoglobin per red cell and expressed in picograms. - Mean cell (corpuscular) hemoglobin concentration (MCHC): It indicates the average concentration of hemoglobin in a given volume of packed red cells and expressed in grams per deciliter. - Red cell distribution width (RDW): RDW is a quantitative measure of anisocytosis and is expressed as percentage.

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SECTION 1  Disorders of Red Cells Table 2.1: Normal range for red cell and other parameters At birth

Men

Women

Red cell count

5 to 7 million/cu mm (5–7 × 1012/L)

4.5 to 5.5 million/cu mm (4.5–5.5 × 1012/L)

3.8 to 4.8 million/cu mm (3.8–4.8 × 1012/L)

Hemoglobin (Hb)

14–22 g/dL

13–17 g/dL

12–15 g/dL

Hematocrit (Hct) or 45–70% packed cell volume (PCV)

40–50%

36–46%

Reticulocyte count

1–7%

0.5–2.5%

0.5–2.5%

MCV

100–120 fL

82–100 fL

82–100 fL

MCH

31–37 pg

27–32 pg

27–32 pg

MCHC

30–36 g/dL

31–35 g/dL

31–35 g/dL

RDW

13–18%

11.5–14.0%

11.5–14.0%

Red cell indices

ANEMIA Definition of Anemia •• Anemia is defined as the decrease below normal limit (below the reference level for the age and sex of the individual) of the hemoglobin concentration, erythrocyte count or hematocrit (ratio of packed red cells to total blood volume). •• It can also be defined as a reduction of the total circulating red cell mass below normal limits. Red cell mass is the volume of the red cells in the body. Normal red cell mass for men is 26–32 mL/kg and for women is 23–39 mL/kg. •• Functionally, it is defined as the decrease in the oxygen-carrying capacity of the blood, which leads to tissue hypoxia. Anemia is not a disease but it is the expression of underlying disease and from the treatment point of view, it is necessary to identify the cause of anemia. Anemia may be absolute, when there is decreased red blood cell (RBC) mass, or relative, when associated with a higher plasma volume. Relative anemia may occur in the third trimester of pregnancy due to hemodilution (spurious anemia) and is not a disease. But the term anemia is conventionally used for absolute anemia.

Classification of Anemia There are several classifications of anemia. Two commonly used are: 1. Morphological classification (Table 2.2): It is based on: (1) red cell size (normocytic, microcytic, or macrocytic), and (2) degree of hemoglobinization, reflected by the color of red cells (normochromic or hypochromic). 2. Etiological classification: Based on the cause and the underlying mechanisms of production of anemia (Table 2.3).

Clinical Features of Anemia Irrespective of the cause, anemia when severe, presents with certain clinical features. The symptoms depend on four main factors:

CHAPTER 2  Classification of Anemia Table 2.2:  Morphological classification of anemia Type of anemia

Microcytic hypochromic

Normocytic normochro- Macrocytic mic

Size of RBCs

Smaller than normal

Normal

Larger than normal

Central pallor in RBCs

More than 1/3

Normal

Normal

Mean corpuscular volume (MCV)

Reduced (100 fL)

Mean corpuscular hemoglobin concentration (MCHC)

Reduced (