Systemic Mastocytosis with Associated Acute Myelogenous Leukemia

Systemic mastocytosis (SM) is a condition associated with a clonal neoplastic proliferation of mast cells. Approximately 40% of patients with SM present with an associated clonal hematological non-mast cell lineage disorder. Patients presenting with SM-acute myeloid leukemia (AML) have the worst prognosis. We present a case of a 62-year-old woman who was diagnosed with SM-AML. After initial treatment with a standard regimen of cytosine arabinoside (Ara-C)/idarubicin, her bone marrow showed residual blasts. She was subsequently treated with a second induction regimen of clofarabine and high-dose Ara-C, which resulted in remission of AML, although a residual mast cell infiltrate persisted in her bone marrow. After consolidation therapy with clofarabine/Ara-C, the patient received a stem cell allograft. A follow-up bone marrow showed no residual blasts but persistent mast cells occupying about 5% of the marrow volume.