RESUMO
Herein we are presenting the clinical, morphological and cytochemical characteristics of five cases of acute megakaryoblastic leukaemia (AML-M7) seen by us over a period of five years (Jan 1996-Dec 2000). Morphological assessment revealed marked polymorphism of blast cells and platelets both in the peripheral blood and bone marrow smears in all cases. Size of the blast cells ranged from very small to very large multinucleated cells, with variable chromatin pattern and number of nucleoli. More differentiated megakaryocytic cells showing cytoplasmic blebs, protrusions and platelet budding with bizarre platelet morphology were characteristic features suggesting the diagnosis. Cytochemical stains like myeloperoxidase, sudan black and PAS were positive in 5-15% of blast cell. Coagulation studies revealed a normal coagulation profile, whereas platelet studies showed marked impairment in aggregation of platelets with ADP and adrenalin with a normal PF-3 availability.