A case of chronic myelomonocytic leukemia who developed pericardial effusion during stably controlled leukocytosis.

We report a rare case of chronic myelomonocytic leukemia (CMML) with pericardial effusion. After receving the diagnosis of CMML, she had been successfully treated with hydroxycarbamide (HU). However, she was admitted to our hospital due to pericardial effusion. The majority of the cells in the pericardial fluid were monocytes. We made the diagnosis of pericardial involvement with CMML cells and intravenously administered etoposide (100 mg/body daily for 5 days). Although CMML cells disappeared from the peripheral blood, the pericardial effusion still persisted. This case indicates that pericardial effusion is a possible and life-threatening complication in CMML patients despite stably controlled leukocytes.