Abstract
A 70-year-old man who had been observed under the diagnosis of refractory anemia with excess of blasts (RAEB) was admitted to our hospital because of fever and wheezing. Physical examination revealed mild hepatomegaly without splenomegaly. Laboratory data showed moderate anemia and thrombocytopenia. Bone marrow was hypocellular with dysplasia of all three hematopoietic cell lines. Five months after the diagnosis of RAEB, the peripheral monocyte count increased more than 1,000/μl, indicating the transformation of RAEB into chronic myelomonocytic leukemia (CMML). At the end stage, the peripheral monocyte count exceeded 100,000/μl. The urinary excretion of lysozyme and serum lactic dehydrogenase were markedly elevated. Most monocytes were in mature form but were poorly stained with α-naphtyl butyrate esterase. Karyotypic analysis which showed a normal pattern on admission revealed complex abnormalities after the evolution of RAEB into CMML. These findings indicate that the monocytes had the neoplastic nature. The anabolic steroid, vitamin D3, and low dose cytarabine had no benefit. He died from respiratory failure seven months after the diagnosis of RAEB. Autopsy revealed extensive infiltration of leukemic cells. This case is informative in regard to the transformation of RAEB into CMML, with subacute course, in association to the clonal evolution.
