[Systemic mastocytosis].

We record a case of systemic mastocytosis in a 70 year old male whose clinical picture started with abdominal symptomatology (pain and diarrhea) and syncopal episodes, who was found to have hepatosplenomegaly and skin, bone and bone-marrow involvement. Papulo-erythematous lesions appeared over the scar tissue of a previous colyscectomy. Scratching of these lesions produced urtication. Histologically an infiltration of mastocytes was found, being compatible with the diagnosis of systemic mastocytosis with Köebner's phenomenon. We review the most remarkable characteristics of systemic mastocytosis.