Systemic mastocytosis associated with chronic myelomonocytic leukemia: clinical features and response to interferon alfa therapy.

Systemic mastocytosis is a rare disease that shows marked heterogeneity in clinical manifestations and prognosis. It may be associated with hematologic disorders. We describe a patient with systemic mastocytosis associated with chronic myelomonocytic leukemia accompanied by ascites, pleural effusion, and development of skin lesions along a surgical scar. The disease responded well to interferon alfa therapy. This is the second report of successful treatment of mastocytosis with interferon alfa and the first associated with a hematologic malignancy.