The authors report a case of systemic mastocytosis in a 65 year-old woman. The clinical picture was generalized abdominal and extra abdominal lymph nodes, ascites, splenomegaly, and hepatomegaly. As gastro-intestinal symptoms led to suspect a digestive malignant lymphoma; the patient underwent an exploratory laparotomy. The diagnosis of systemic mastocytosis was established by demonstrating an excessive number of mast cells in the cutaneous and extracutaneous tissues (liver, mesenteric lymph, nodes, spleen and bone marrow). Bone marrow biopsy revealed extensive myelofibrosis.