A 74-year-old man without previous treatment was found to have an IgA paraprotein on serum immunoelectrophoresis and Bence-Jones protein on urine immunoelectrophoresis. Serum IgA level was 2,400 mg/dl with depressed IgG and IgM levels. Bone marrow aspiration revealed infiltration by both promyelocytes and plasma cells. Chromosomal abnormalities were found. Electron microscopy showed that promyelocytes had a lamellar structure arranged in a concentric circle pattern. The case was thus diagnosed as multiple myeloma complicated by acute myeloid leukemia. Complete remission of leukemia was achieved with combination chemotherapy. Acute leukemia tends to occur at a relatively high incidence in patients with multiple myeloma who are treated with alkylating agents. But the appearance of acute leukemia in patients with multiple myeloma without previous treatment is very unusual. The possible relationship between multiple myeloma and acute leukemia is discussed.
