Concurrent acute myeloid leukemia and systemic mastocytosis.

A 51-year-old woman presented with concurrent systemic mastocytosis and acute myeloid leukemia associated with a clonal karyotypic anomaly of t(8;21). Cytochemical, histologic, and cytogenetic studies helped in the distinction from a recently described entity: acute myeloid leukemia with marrow basophilia. Although the leukemia responded well to aggressive chemotherapy, the mastocytosis component worsened, illustrating the inherent resistance of mastocytosis to chemotherapy.