[Leiomyosarcoma of the renal vein].

The authors report a new case of leiomyosarcoma of the right renal vein, marked by a rapidly fatal course within 9 months, despite the initial absence of metastasis. This exceptional vascular tumour (only about thirty cases have been published) must be distinguished from primary renal leiomyosarcoma and retroperitoneal leiomyosarcomas involving adjacent structures. This difficult diagnosis was suggested by preoperative CT and angiography. Leiomyosarcomas of the renal vein generally have an unfavourable outcome in the medium term. The prognosis is related to the localized nature of the tumour and the risk of local and distant recurrence. Limited tumour resection is rarely sufficient and radical nephrectomy is usually necessary, possibly associated with a vascular procedure on the inferior vena cava in the case of contiguous extension.