Department of Pathology and Microbiology, The Aga Khan University, Karachi, Pakistan.
A 35-year-old woman had 2-month history of fever and bone pain, with an 8-kg weight loss in one month. Physical examination revealed 7-cm palpable spleen (splenomegaly). On admission, her hemoglobin level was 13.4 g/dL, white blood cell count was 144×109/L, and platelet count was 71×109/L. Bone marrow biopsy showed diffuse infiltration with blast cells. However, two populations of blast cells was observed; one population was large-sized, had abundant granular cytoplasm, and a few had Auer rods; the other population was comprised of medium-sized blast cells with scant and agranular cytoplasm (