Systemic mastocytosis in a child with t(8;21) acute myeloid leukemia.

Mastocytosis is primarily limited to the cutaneous variant in pediatric patients. Systemic mastocytosis (SM) has been associated with t(8;21) acute myeloid leukemia (AML) in adults. We provide the first report of a child with t(8;21) AML, diagnosed with asymptomatic SM following four cycles of chemotherapy. Unlike most adults with SM/AML, she was not found to have a c-KIT (D816V) mutation. SM persisted in the bone marrow after completion of chemotherapy, and her AML relapsed 9 months off-treatment. Although she achieved a second remission, mastocytosis persists in the marrow. Pediatric patients with t(8;21) AML/SM may represent a high-risk group despite favorable cytogenetics.