[Pleomorphic cell sarcoma responsible for a picture of retroperitoneal fibrosis].

A 68 years-old patient was followed-up during five years for idiopathic retroperitoneal fibrosis. The diagnosis was based on repeated examinations with two laparotomies as well as numerous biopsies. At autopsy a primary retroperitoneal sarcoma was found. This case points out the difficulty to differentiate idiopathic from malignant retroperitoneal fibrosis. Only one similar case was published in the literature.