[Acute monoblastic leukemia (M5a) with dysmegakaryocytopoiesis associated with t(16;21) (p11;q22)]

We report a 24-year-old woman who had acute monoblastic leukemia associated with t(16;21) (p11;q22). She was referred to our hospital in April 1992 because of high fever and hemorrhagic diathesis. Physical examination on admission showed no hepatosplenomegaly. The hemoglobin was 5.1g/dl, platelet count 1.7 x 10(4)/microliters, the white blood cell count 18,700/microliters. Bone marrow aspirate showed that 86% of nucleated cells were monoblasts which were positive for peroxidase and alpha-naphtyl butyrate esterase. She was diagnosed as having M5a. Dysmegakaryopoiesis, such as micromegakaryocytes and megakaryocytes with multiple small separated nuclei, was seen in the bone marrow. Chromosomal analysis revealed t(16;21). Complete remission was achieved after two courses of BHAC-DMP therapy, but dysmegakaryopoietic features remained. She relapsed in September 1992. Review of the literature and this patient indicate that acute nonlymphocytic leukemia with t(16;21) is associated with multilineage leukemic differentiation.