[Recurrent syncope as a presenting symptom of systemic mastocytosis].

A 48-year-old man presented with recurrent syncope which was preceded by facial edema and difficulty in breathing. Physical examination, laboratory tests, abdominal CT and bone scan were all within normal limits. Bone marrow biopsy was consistent with mastocytosis. Systemic mastocytosis consists of a spectrum of disorders characterized by aberrant proliferation of tissue mast cells, and are mainly related to mast cell mediator release.