Symptomatic Response to Imatinib Mesylate in Cutaneous Mastocytosis Associated with Chronic Myelomonocytic Leukemia

Mastocytosis is an uncommon disorder defined by increased and abnormal mast cells in one or more tissues. Cutaneous mastocytosis (CM) is limited to the skin, with varying degrees of rash, pruritus, and disfigurement. Systemic mastocytosis (SM) typically involves the bone marrow, sometimes in association with other bone marrow disorders, including chronic myelomonocytic leukemia (CMML). Mastocytosis has been associated with somatic mutations in the gene encoding the tyrosine kinase Kit, leading to identification of Kit as a therapeutic target. The Kit inhibitor imatinib mesylate is approved for aggressive SM. We present an unusual patient with disabling pruritus from telangiectasia macularis eruptiva perstans, a subtype of CM, and CMML, but with no evidence of systemic mast cell disease. She was treated with imatinib and experienced marked improvement in her pruritus. Concomitant CM and CMML have not previously been reported, and the present report is the first of successful imatinib therapy in an adult patient with CM.