We report a 38 years old female who, since her childhood, had a history of precisely limited, fixed maculo papular dark brown cutaneous lesions in the trunk and extremities. These lesions become erythematous or urticarial after rubbing, medication intake or scratching. She also had frequent episodes of tachycardia, flushing, headache, abdominal pain, arthralgia, diarrhea and vomiting. She was hospitalized in three occasions due to high frequency tachycardia, hypotension, generalized urticarial erythema and clouding of consciousness. Three of these episodes occurred after the ingestion of antinflammatory drugs or acetylsalicylic acid. Mastocyte infiltration was confirmed in skin and bone marrow biopsies and in bone scintiscan. The use of H1, H2 blockers and mastocyte stabilizers gave partial relief to the patient.