Color Atlas of Hematology - Practical Microscopic and Clinical ...

138 Erythrocyte and Thrombocyte AbnormalitiesHypochromic Anemia with HemolysisThalassemiasA special form of hypochromic anemia mostly affecting patients of Mediterraneandescent presents with normal erythrocyte count, decreasedMCH, and clinical splenomegaly. The smear displays erythrocytes withcentral hemoglobin islands (target cells). These cells do not necessarilypredominate in the CBC: the most revealing field views show at most 50%target cells in addition to clear anisocytosis and frequent basophilic stippling.Occasional normoblasts give a general indication of increased erythropoiesis.Although target cells are also nonspecific, since they can occurin such conditions as severe iron deficiency or obstructive jaundice, thisoverall picture should prompt hemoglobin electrophoresis. The sampleconsists of ACD-stabilized blood at 1 :10 dilution. A significant increase inthe HbA 2 fraction confirms a diagnosis of thalassemia minor, the heterozygousform of the disease. Thalassemia major, the homozygous variant, isfar rarer and more serious. In this form of the disease, in addition to thetarget cells, the CBC shows a marked increase in red precursor cells. Hbelectrophoresisshows a predominance of HbF (the other hemolytic anemiasare usually normochromic, see p. 140).