Hematopoietic and Lymphatic Tissues

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Hematopoietic and Lymphatic Tissues

Cells of the hematopoietic and lymphatic tissues serve vital functions of host defense, internal homeostasis, and bodily intactness. They all originate from the same stem cell population and in their functional activities interact in various ways (see chapter 1). Disorders in one cell population may thus cause reactions in the other. For this reason, the hematopoietic and lymphatic systems are discussed together. Just as there are a large number of different cell populations with various differentiation stages and functional activities, so are there a multitude of human diseases of the blood and lymphatic systems. The most common and important are discussed in this chapter. The most common leading symptoms of all these diseases are infection, hemorrhage or thrombosis, and anemia.

Neoplastic Lymphatic Disorders

Malignant neoplasias of the lymphatic tissues are collectively identified as malignant lymphomas (MLs) or, when malignant cells circulate in the blood, lymphocytic leukemias. There are 2 major groups of MLs: Hodgkin lymphomas (lymphogranulomatosis) and non-Hodgkin lymphomas (NHLs). Hodgkin lymphoma, or Hodgkin disease (HD), is distinguished from NHL by its polymorphic features, including certain inflammatory components such as fibrosis and occasional regression simulating nonneoplastic diseases, which eventually may progress to ML. Although it is a lymphatic malignancy, it is accompanied by a large number of associated nonneoplastic cells, which may influence the course and progression of the disease. NHL, by contrast, begins as malignant clonal proliferations. Transition from HD to NHL and combinations of HD with certain types of NHL have been observed (HD and chronic lymphocytic leukemia [CLL] or follicular center cell lymphoma [FCC]; see Table 10-4).

Along with diagnosing an ML as HD or NHL and determining the subclassification based on histologic, immunologic, and cytogenetic markers, staging of disease extent helps to determine the appropriate treatment and the life expectancy of the patient. Staging of all lymphomas is similar: stage I indicates involvement by lymphoma of 1 lymph node site (e.g., axillary, neck); stage II indicates involvement of 2 lymph node sites on the same side of the diaphragm (e.g., neck and axillary, or left and right inguinal); stage III indicates involvement of lymph nodes on both sides of the diaphragm; and stage IV indicates involvement of lymphatic and extralymphatic sites (e.g., liver, spleen, bone marrow). ML may arise from sites other than the lymph nodes. These are grouped together as extranodal lymphomas and have different staging.

TABLE 10-1

CLASSIFICATION OF ANEMIAS*

Category RBCs Characteristics
Blood loss, acute Initially: normochromic, normocytic
Later: hypochromic reticulocytosis
Acute volume depletion
RBC reduction secondary to fluid influx
Rapid RBC regeneration
Blood loss, chronic Hypochromic Reduced iron stores
Increased Destruction of Erythrocytes
Hemolytic anemias   Features of hemolysis and tissue siderosis
Bone marrow: significant erythropoietic hyperplasia
Splenomegaly
Immunologic Reticulocytosis Autoantibodies against RBC (infection or drug induced)
Isohemagglutinins (transfusion induced, erythroblastosis fetalis)
Mechanical Schistocytes Microangiopathic:
 Hemolytic uremic syndrome
 Thrombotic thrombocytopenic purpura
 Trauma by intracardiac artificial devices
 Multiple hemangiomas (e.g., hepatic)
Hereditary Spherocytosis
Elliptocytosis
Sickle cells
Hypochromic, microcytic
Heinz bodies
RBC membrane and cytoskeleton deficiencies
Hemoglobinopathies: sickle cell anemia, thalassemia
Enzyme deficiencies (e.g., of hexose monophosphate shunt)
Deficient Erythropoiesis
“Stem cell” defect Normochromic,
Normocytic to mildly macrocytic
Aplastic anemia (with pancytopenia), pure red cell aplasia secondary to myelofibrosis (with thrombocytopenia, splenomegaly)
Maturation defect Megaloblastic
Anisocytic
Hypochromic
Poikilocytic
Pernicious anemia (vitamin B12 deficiency), folate deficiency, anemia, iron deficiency (infection, tumor, chronic blood loss)
Hb synthesis defect Sideroblasts Sideroblastic anemia

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normochromic: normal color (i.e. normal Hb content); normocytic: normal size and shape of RBC; hemolytic: red cell lysis

*Hb indicates hemoglobin; RBC, red blood

TABLE 10-2

REACTIVE HEMATOPOIETIC HYPERPLASIA (NONLYMPHATIC)

Involved Cell Compartment Cause
Erythrophilic, neutrophilic, and megakaryopoiesis Blood loss or transient myelotoxic agents
Preferentially neutrophilic Pyogenic bacterial infections, extensive tissue necroses
Less extensive: drugs such as SCF, steroids
Neutrophilic and histiocytic (frequently with lymphocytes and eventual granuloma formation) Chronic infections such as by intracellular organisms (e.g., Rickettsia, Yersinia, Salmonella, mycobacteria), mycoses, collagen-vascular diseases (e.g., lupus erythematosus)
Preferentially histiocytic Protozoal infection (e.g., malaria)
Suggestive viral infection (hemophagocytic syndrome)
Phagocytosis defects (infantile septic granulomatosis, Chediak-Higashi syndrome, and others)
Metabolic (various storage diseases: morbus Gaucher, morbus Niemann-Pick, and others)
Eosinophilic Allergic diseases
Parasitic infestations
Viral infections with immune complex reaction (e.g., Hodgkin disease)
Treatment with IL-2
Basophilic Certain allergic diseases (e.g., food allergies)
Certain endocrine disorders (e.g., myxedema)
Estrogen treatment

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SCF indicates colony stimulating factor; IL, interleukin.

TABLE 10-3

CLASSIFICATION IN SUBTYPES OF ACUTE MYELOPROLIFERATIVE DISEASES*

FAB Class Subtype Name Abbreviation Proportion of Acute Myeloproliferative Diseases (%)
M0 Acute myeloblastic leukemia, stem cell (i.e., minimal differentiation) AML 3-5
M1 Acute myeloblastic leukemia without maturation AML 15-20
M2 Acute myeloblastic leukemia with maturation AML 25-30
M3 Acute promyelocytic leukemia APL 5-20
M4 Acute myelomonocytic leukemia AMML 20-30
M5 Acute monoblastic leukemia AMOL 2-9
M6 Acute erythroleukemia AEL 3-5
M7 Acute megakaryoblastic leukemia   3-12

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FAB indicates French-American-British classification.

*Acute myeloproliferative diseases are clonal neoplastic disorders of hematopoietic stem cells, the classification of which is determined by their preferential cytologic differentiation.

Adapted from Hoffman R et al. Hematology. Philadelphia: Churchill-Livingstone; 2000.

Peripheral B-Cell Neoplasias Pewripheral T-Cell and NK-Cell Lymphomas

1. B-cell chronic lymphatic leukemia (B-CLL) or prolymphocytic leukemia (B-PLL)

2. Small cell lymphocytic lymphoma

3. Lymphoplasmacytoid lymphoma (LPL) or immunocytoma (IC)

4. Mantle cell lymphoma

5. Follicular center cell lymphoma, follicular pattern (FCCf)

6. Follicular center cell lymphoma, small cell, diffuse pattern (FCCd)

7. Marginal zone lymphoma (MZL)

8. Margonal zone lymphoma of the spleen (SLVL)

9. Hairy cell leukemia (HCL)

10. Plasmacytoma/multiple myeloma

11. Diffuse large cell B-cell lymphoma subtype: primary B-cell lymphoma of mediastinum (of thymic origine)

12. Burkitt lymphoma

13. B-cell lymphoma of high malignancy of Burkitt type

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