Mastocytosis : Hematologic Abnormalities

Hematologic abnormalities in systemic mastocytosis (SM) include peripheral blood eosinophilia (most common), anemia, thrombocytopenia, neutropenia, and leukocytosis. Significant numbers of circulating mast cells (shown here) are rare in SM and are diagnostic of mast cell leukemia when they make up >10% of leukocytes. Bone marrow failure and the resultant cytopenias are seen only in aggressive variants or in mast cell leukemia. About 30% of patients with SM have an associated hematologic malignancy such as chronic myelomonocytic leukemia or myelodysplastic/myeloproliferative neoplasm, unclassified.