[Gastric interdigitating reticulum cell sarcoma: unusual presentation of a histiocytic tumor].

Histiocytic sarcoma, proliferation arising from immunoregulatory effector system cells, is a very rare and recently recognized tumor. Diagnosis is based on immunohistochemical and molecular genetic study, which allows to distinguish histiocytic sarcoma from lymphocytic proliferation, such as non-Hodgkin's lymphoma. We report the case of a gastric interdigitating reticulum cell sarcoma, treated by resection and chemotherapy.