Acute Leukemia With Megakaryocytic Differentiation : A Study of 12 Cases

Acute leukemia with megakaryocytic differentiation has been an uncommonly recognized disorder. We used specific monoclonal and polyclonal antibody reagents (HP1 -1 D antibody and anti-factor VIII antibody. respectively) and an immunocytochemical staining technique to identify the megakaryocytic nature of the leukemic cells of 1 2 patients who presented with acute leukemia. The leukemic cells of our patients demonstrated the presence of one or both of these plateletand megakaryocyte-related antigens. but were negative for all of the commonly employed cytochemical and immunocytochemical staining reactions. except for diffuse acid phosphatase activity and granular PAS positivity. Morphologically. the leukemic cells varied in size from 10 to 40 tm in diameter. frequently had cytoplasmic budding. and contained occasional vacuoles and/or peroxidase-negative azurophilic granules. Five patients presented with syndromes of acute myelofibrosis. and seven patients had otherwise unclassifiable acute leukemias. including three patients who had secondary leukemias.