[Evolution to megakaryoblastic leukemia observed in myelodysplastic syndrome with erythrolekemia-like features].

A 63-year-old man was admitted because of anemia and thrombocytopenia. The bone marrow was hypercellular with 66.6% erythroblasts with dysplasia and 19.8% blasts. Cytogenetically, MAKA (major karyotypic aberrations) containing 5q-, -7, -17, with karyotypic instability was observed. A diagnosis of erythroleukemia (FAB M6) was made. Six months later, immature neutrophils increased in the peripheral blood, and blasts and promyelocytes increased to 25.8% and 20.0% of marrow cells, respectively. Three months later, blasts asts increased to 33.0% in the peripheral blood. They were ultrastructually positive for platelet peroxidase. Phenotypically, 69% and 63% of blasts were positive for CD41b (GPIIb/IIIa) and CD42a (GPIb), respectively. Bone marrow biopsy showed marked proliferation of blasts and dysplastic megakaryocytes accompanied by reticulin fibrosis. These findings suggested evolution to megakaryoblastic leukemia (FAB M7). In most cases, M6 defined by the FAB criteria is stem cell disorder with multilineage involvement and major erythroid component. M6-like features may be observed in the evolutive phase to acute leukemia from myelodysplastic syndrome (MDS).