[Complete remission of essential thrombocythemia after recovery from severe bone marrow aplasia induced by busulfan treatment].

A 63-year-old woman was found to have thrombocythemia and was referred to our hospital for further evaluation in September 1990. Peripheral blood showed platelet 170.0 x 10(4)/microliter, WBC 14,900/microliter and Hb 9.8 g/dl. Bone marrow was hypercellular with increased megakaryocytes and normal karyotype. She was diagnosed as essential thrombocythemia (ET), and treated with 2 mg of busulfan daily for 3 months until her platelet count decreased to 33.1 x 10(4)/microliter. Busulfan was given again for 40 days (a total of 80 mg) in another hospital when the platelet count increased to 71.1 x 10(4)/microliter in September 1991. In December 1991, she was admitted to our hospital because of pancytopenia. Examination of blood revealed platelet 0.4 x 10(4)/microliter, WBC 1,800/microliter and Hb 7.0 g/dl with hypocellular marrow. A diagnosis of busulfan-induced severe bone marrow aplasia was made. We administered metenolone acetate 15 mg and G-CSF 300 micrograms daily. Blood transfusions were given frequently. However, no effect was observed during her hospitalization. After discharge, G-CSF 600 micrograms and erythropoietin 24,000 units were continued twice a week in combination with metanolone acetate. Pancytopenia gradually began to improve as of June 1992, and then trilineage recovery was achieved in March 1994 with platelet 13.3 x 10(4)/microliter, WBC 5,500/microliter and Hb 12.1 g/dl. The platelet count has been within the normal range for more than 2 years after recovery.