hematology .pdf

Hematopathology Learning outcomes: After this session you should be able to: 1.Have a basic understanding of hemopoiesis and blood formation. 2.Basic principle of erythropoiesis. 3.General hematological investigations particularly to anemic patient. 4.Definition, classification, and clinical present...

Hematopathology Learning outcomes: After this session you should be able to: 1.Have a basic understanding of hemopoiesis and blood formation. 2.Basic principle of erythropoiesis. 3.General hematological investigations particularly to anemic patient. 4.Definition, classification, and clinical presentations of anemias. 5.Iron metabolism and iron deficiency anemia. 6.Differential diagnosis of hypochromic anemia. 7.B12, FA metabolism and megaloblastic anemia. Blood formation Blood is a suspension of non-dividing end stage cells in plasma. Haemopoiesis: is process of proliferation, differentiation and mature blood cell release. It includes erythropoiesis, leucopoiesis and thrombopoiesis processes. Sites of hemopoiesis: Fetus 0-2 m (yolk sac) 2-7 m (liver, spleen) 5-9 m (Bone marrow) Infant Bone marrow (all bones) Adult Bone marrow (axial skeleton and proximal end of long bones). Structure of BM: Bone marrow consist of hemopoietic and stromal cells. Hempoietic tissue including stem, progenitor, precursor and mature cells. Stem cells can give rise all cell lines, able to self-renewal (proliferation) and differentiation, present in few and constant number and require certain growth factors and suitable microenvironment to work. Progenitor cells present in early and late types, and consider intermediate stage of multi-lineage or uni-lineage cells with increase differentiation over the proliferation. Precursor cells specific for single line and morphologically recognizable in the bone marrow. Stem cells Progenitor cells Precursors cells Mature cells Structure of BM: Red marrow is the active marrow and considered as the site of hemopoiesis, while yellow marrow is the inactive marrow consist mainly of fat cells. Fat marrow (yellow marrow) is able to reverse into red marrow (active marrow) in many diseases when function of active marrow is required. Percentage of active hemopoiesis will differ according to the age and gradually reduce with progression of the age in compare with percent of fat tissue: In adult (fat: haemopoietic tissues) 50%:50% In child (fat: haemopoietic tissues) 25%:75% In elderly (fat: haemopoietic tissues) 75%:25% Extramedullary hemopoiesis means process of hemopoiesis occuring outside the BM (mainly in liver and spleen) , it occurs in certain conditions as in sever chronic hemolytic anemia and BM fibrosis. Erythropoiesis It mean formation of RBC and require 7 days for complete new RBC formation. This process requires stem, progenitor and precursor cells for complete formation of mature RBC. Important cells in the BM for this process are precursor cells which including: Proerythoblast. Early normoblasts. Intermediate normoblasts. Late normoblasts. Reticulocytes. The cell gradually loss their nucleus until formation of reticulocyte as last precursor cell without nucleus. Reticulocytes: non nucleated red cells with diffusely basophilic cytoplasm due to remaining ribosomal RNA, still able to synthesis the Hb, slightly larger than mature RBC, it remains in BM about 2 days then release to circulation and remains 1-2 days to complete their maturation in the spleen. Normal range in peripheral blood is 0.5-2.5 %. Mature RBC: non nucleated cells of 8µm in diameter, biconcave, flexible, able to pass through microcirculation with minimal diameter 3.5 µm. Life span 120 days, generate energy as ATP and generate reducing power. Normoblast (precursor of RBC) normally present in the BM and not present in peripheral blood and when appear called nucleated RBC (NRBC). Control of erythropoiesis: Functional feedback: achieved by Erythropoietin (Epo). Certain hormones, like growth hormone and androgen enhance erythropoiesis, while estrogen suppresses erythropoiesis. Nutritional factors like FA, B12, iron, B6, B2, vitamin C and E. Erythropoietin (Epo): It is a glycoprotein produced mainly by the kidney in the adult, stimulates red cell progenitors and precursors cells for RBC formation from the BM. Secretion of Epo is triggered by reduced oxygen tension of blood: Reduced Hb (anemia). Hypoxia (cardiac and lung disease). Damage to renal circulation. Epo of great clinical significant in many disorders using recombinant Epo like end stage renal disease and anemia of chronic disease. Initial hematological investigations Complete blood count; include Hb level, WBC count, platelets count, RBC indices and WBC differential count. Blood film stained usually with Leishman stain, to examin red cell morphology, leucocyte morphology, leucocyte differential count and platelet morphology. ESR (erythrocyte sedimentation rate): red cell sedimentation depends mainly on plasma proteins as fibrinogen and other acute phase proteins that increase the red cells rouleaux and extend of their sinking. Reticulocytes count (Retic count) Reticulocyte: are young, immature non nucleated red cells containing remnant RNA. Increase retic count occur in hemolytic anemias, hemolysis and recovery state from anemia. Decrease retic count occur in bone marrow failure. Retic count: is the estimation of number of reticulocytes among mature peripheral RBC detected by a special stain, normal range 0.5-2.5 %. Blood film Bone marrow examination: There are two types of marrow procedures: 1.Bone marrow aspirate: done from iliac crest or sternum, in which a specimen is aspirated using a wide bore needle from the active marrow, smeared, stained and then examined for any abnormalities. 2.Bone marrow biopsy: here a core of bone marrow tissue is taken, processed and stained as in histopathological specimens. Main indications of BM examination: 1.Marrow infiltration with leukemia, lymphoma, secondary carcinomas and myelofibrosis. 2.Cytopenias of unexplained causes: leucopenia, thrombocytopenia, anemia. Bone marrow examination Bone marrow aspiration Bone marrow biopsy Definition of terms in RBC disorders Normocytic: normal size (normal MCV). Normochromic: normal Hb amount (normal MCH), RBC showing central pallor less than 1/3 of cell diameter. Hypochromic: decrease in Hb amount (decrease in MCH), central pallor more than 1/3 of cell diameter. Anisocytosis: variation in RBC size as microcytic (decrease in MCV), macrocytic (increase in MCV). Poikilocytosis: variation in RBC shape as sherocytes, target, tear drop, sickle, fragmented, oval, rod cells, etc.. Polychromasia, rouleaux formation and agglutination of RBC. Red cell indices Hemoglobin (normal range for male 13.5– 17.5 g/dl, female 11.5-15.5 g/dl). Packed cell volume (PCV) also called Hematocrit (Male 40-52 %, Female 36-48 %). RBC count (Male 4.5-6.5 x 1012/L, Female 3.9-5.6 x 1012/L). MCV: mean cell volume MCH: mean cell Hb MCHC: mean cell Hb concentration RDW: red cells distribution width (80-95 fl). (27-34 pg). (32-36 g/dl). (12-15 %). Example of complete blood counts and blood film Red blood cells indices Platelets count: ×109/L. 332 Hb: 14.1 gm/dl. Total WBC count: 9.7 × 109/L PCV (Hematocrit): 43.2 % Differential count (%) 12 RBC: 4.8 × 10 /L MCV: 88 fl MCH: 28 pg MCHC: 32 gm/dl. RDW: 18 Retic count: % Neutrophils: Lymphocytes: Monocyte: Eosinophils: Basophiles: 62 35 3 0 0 % ESR: 8 mm/hr. Blood film morphology RBC: Normocytic normochromic red cells. WBC: Look normal in total, differential count and morphology Platelets: Look normal in count and Red blood cells disorders (Anemias and Polycythaemia) Normal Hb is: Male: 13.5-17.5 gm/dl Female:11.5-15.5 gm/dl (PCV 40-52 %) (PCV 36-48%) Anemia: decrease in Hb concentration below normal range for age and sex. Polycythemia: increase in the Hb concentration above the upper limit of normal for age and sex In male In female Hb