[Hypoplastic myelodysplastic syndrome progressing to acute myelocytic leukemia (M2) after treatment with G-CSF and immunosuppressants].

A 34-year-old woman was admitted to our hospital because of pancytopenia. She had been given a diagnosis of idiopathic thrombocytopenic purpura during her first pregnancy about 7 years earlier. The patient received a diagnosis of severe aplastic anemia (AA) and was treated with methylprednisolone, cyclosporin A, and granulocyte colony-stimulating factor (G-CSF), but no hematological improvement was observed. Six months later, myeloblasts appeared in the patient's peripheral blood, and she was given a diagnosis of acute myelocytic leukemia AML (FAB : M2). No chromosomal abnormalities were found. As some dyshematopoietic features had been observed in the bone marrow when the patient was first given a diagnosis of AA, it is conceivable that she already had hypoplastic myelodysplastic syndrome (MDS) then. She was treated according to the JALSG-AML92 protocol and achieved complete remission (CR). In this case, the long-term administration of G-CSF may have played an important role in the transformation of MDS into AML. It may be difficult to strictly distinguish AA from hypoplastic MDS with slight dysplastic features, as in this case, because we have no established criteria. Recently the incidence of MDS/AML in AA patients undergoing G-CSF treatment has become a concern. We should be careful about ruling out hypoplastic MDS when diagnosing a condition as AA, especially when therapy includes G-CSF. The patient is still in CR 26 months after intensive combination chemotherapy.