[Megakaryoblastic leukemia which developed from therapy-related MDS with myelofibrosis].

A 56-year-old man had a leiomyosarcoma of the small intestine in 1987. After surgery, he received cyclophosphamide for 2 years. In December, 1990, he exhibited severe pancytopenia. His hematological data were as follows: Hb 7.4g/dl, ret. 0.8%, WBC 1,700/microliters with leukoerythroblastosis and 2.8 x 10(4)/microliters platelets. A bone marrow aspiration was a dry tap. A bone marrow biopsy specimen showed a hypercellular marrow with myelofibrosis, leukemic infiltration (10.2%) and slight dyserythropoiesis. Both PPO and GPIIb/IIIa reaction were positive for blast cells and atypical megakaryoblasts. A diagnosis of MDS with an abnormality in megakaryocytic lineage was made. The patient was treated with 1,25-dihydroxy-vitamin D3, however this therapy was temporary and he developed into acute megakaryoblastic leukemia (M7). This report suggested that some cases of therapy-related leukemia (TRL) mainly involve megakaryocytic lineage and are diagnosed as MDS with myelofibrosis which transform to M7. The fact that PAS stain of erythroblasts in the patient reported here was positive may suggest involvement of development of more precise immunological markers of differentiation and EM study will permit better diagnosis of TRL and may therefore facilitate new therapeutic approaches.