[Acute myelofibrosis terminating in acute myelomegakaryoblastic leukemia].

We report a case of acute myelofibrosis (AMF) developing into acute myelomegakaryoblastic leukemia. A 33-year-old woman was admitted to our hospital because of fever and chest pain. On physical examination, hepatosplenomegaly was not noticed. Pancytopenia and a small number of blast cells were observed in the peripheral blood. Poikilocytosis was not detected. Bone marrow examination revealed dry tap on aspiration, and moderate increase in reticulin fiber on biopsy. The diagnosis of AMF was made. Eight months later, blast cells markedly increased. Surface marker was investigated and MCS-2 (CD13), C17 (CDw41) and P2 (CDw41) were found to be positive. Electron microscopic examination revealed that blast cells were composed of PPO-positive cells and MPO-positive cells. Based on these findings, it was considered that the patient developed acute myelomegakaryoblastic leukemia. Recently AMF is thought to be a state to have the ability to develop into various types of acute leukemia. Adequate therapy may be required before the development of leukemia.