[A strange case of phlebitis].
Report of a rare case concerning an elderly man (81 years) suffering from a leiomyosarcoma of the leg already metastasized to the lungs, discovered in connection with a suspected thrombophlebitis. This sarcoma developed from the smooth muscle of a leg vessel, probably a vein. Leiomyosarcoma is a malignant mesenchymal tumor of specialized connective tissue, with a strong potential for local proliferation and metastatic spread. It usually involves the uterine muscle or the wall of the digestive tract, as well as the large vessels of the abdomen and thorax, the prostate very seldom, and only exceptionally a peripheral vein as in this case. The diagnosis suggested by imaging techniques (in particular MRI) is first and foremost immunohistochemical. The treatment is surgical when possible, associated with radiotherapy and chemotherapy as appropriate. The prognosis is especially poor when the diagnosis is made at the metastatic stage.