Abstract
A 55-year-old man, who had been diagnosed as the hypereosinophilic syndrome presenting persisting eosinophilia for 4 years (>3,000/μl) of unknown origin and eosinophilic infiltration of the gastrointestinal mucosa, was admitted because of the appearance of blastoid cells (7%) with monocytosis (64%) in the peripheral blood. Bone marrow study revealed a marked proliferation of α-naphthyl-acetate-esterase positive monoblasts (80.6%) without an increase of eosinophils. A dignosis of acute monoblastic leukemia preceded by the hypereosinophilic syndrome was made.
Bone marrow cells from the patient were cultured with various inducers of differentiation, and induced to differentiate into monocytes and macrophages in various degree. The most effective inducer was dexamethasone and about 90% of the cultured cells were induced functionally and morphologically into mature macrophages by 10-6 M dexamethasone.
The patient was treated with prednisolone (30 mg per day). Soon after the beginning of the treatment, a rapid disappearance of monoblasts, a gradual decrease of monocytes and an increase of hemoglobin were observed in the peripheral blood. Two months later, he achieved complete remission without passing through a severe cytopenic phase.
Not only the cytotoxic effect but the differentiation-inducing effect of prednisolone may lead to the successful induction of remission in this case.
