[Transient promyelocytic expansion in primary myelofibrosis]

A 46-year-old man with primary myelofibrosis developed polyarthralgia. Marked hepatosplenomegaly was noted, and hematological examinations revealed a white cell count of 25,600/microliters with 42% promyelocytes and thrombocytopenia. The promyelocytes were positive for CD4 antigen and nonspecific esterase as well as peroxidase. Cytogenetic analysis of circulating mononuclear cells showed the trisomy of No. 22 chromosome in 3 of 5 cells examined. Four months later, the patient became asymptomatic, and hematological picture and hepatosplenomegaly returned to the original level. This is the first report describing the transient promyelocytic expansion in myeloproliferative disorders.