[Non-specific esterase positive neutrophils in a case of refractory anemia with excess of blasts].

A 61-year-old woman was admitted with complaint of fever. The peripheral blood showed pancytopenia and bone marrow aspirate showed dysplasia in trilineage blood cells with increased blasts (18.2%). Bone marrow chromosome study revealed a karyotype of 46XX, -6, 3q-, +mar in 19 cells of 20 analyzed. She was diagnosed as refractory anemia with excess of blasts (RAEB). 95% of neutrophils in the bone marrow and 84% of that in the peripheral blood were stained with non-specific esterase using alpha-naphthyl acetate as substrate. On the other hand, the positivity of neutrophils for peroxidase. Sudan black B or chloroacetate esterase was markedly decreased. The phagocytotic activity of neutrophils was increased in comparison with normal control cells. Surface marker analysis of peripheral blood myeloid cells revealed increased expression of monocyte specific markers. These findings suggested that the patient's neutrophils, which were surely neutrophils in morphology, shared also monocyte-specific characters. After treatment with low dose Ara-C, pancytopenia was recovered and blasts in the bone marrow were reduced. Also was decreased non-specific esterase positive neutrophils, indicating that the neutrophils were derived from abnormal myeloid clone.