[Systemic mastocytosis].

Mastocytosis has a highly variable clinical expression, and systemic mastocytosis is occasionally associated with a myeloproliferative or a myelodysplastic disorder. These patients often present without skin involvement and have a very poor prognosis. We report a 72-year-old man with this condition who had spells of flushing and dyspnea, myelofibrosis, and high serum and urine histamine levels.