Acute aleukemic mast cell leukemia: Report of a case and review of the literature.

Mast Cell Leukemia (MCL) is the rarest form of systemic mastocytosis, a rare group of neoplastic disease that result from clonal proliferation of mast cells and their accumulation in one or more organ systems. The diagnosis of MCL is made by meeting the World Health Organization (WHO) 2017 criteria. MCL is further subclassified as leukemic or aleukemic based on presence or absence of circulating mast cells in the peripheral blood and acute versus chronic based on presence or absence of findings indicative of impaired organ function due to mast cell infiltration. A 64-year-old Hispanic male presented with myalgia, diarrhea, urticarial rash, back pain, and fulminant disseminated intravascular coagulation. Bone marrow examination, supplemented by immunohistochemistry results, fulfilled the WHO criteria for the diagnosis of MCL. To the best of our knowledge, this is the first documented case of aleukemic acute MCL in a Hispanic patient.