[Unusual lung localization of histiocytic sarcoma].

Histiocytic sarcoma, proliferation araising from immunoregulatory effector system cells, is a very rare and recently recognised tumor. Diagnosis is based on immunohistochemistry and molecular genetic techniques, which allow to distinguish histiocytic sarcoma from lymphocytic proliferation, such as non-Hodgkin's. We report this rare case of multivisceral histiocytic sarcoma revealed by lung localization and for which the evolution was fatal.