[Sarcomatous recurrence of leiomyoma of the inferior vena cava].

In a 63-year old woman, a surgically removed leiomyoma of the inferior vena cava recurred, 4 years later, as a leiomyosarcoma. These two smooth muscle tumours, one benign the other malignant, seldom involve the inferior vena cava. Both produce few clinical symptoms and therefore are belatedly diagnosed, except for suprarenal or retrohepatic lesions which rapidly exhibit signs of compression. Computerized tomography, angioscans and cavography are necessary to make a provisional diagnosis and determine the operative strategy. The differential diagnosis between leiomyoma and leiomyosarcoma rests on cellular or nuclear atypias, mitotic index and sometimes cytological and staining details showing the myofibril. These tumours develop slowly in the renal segment. Treatment is primarily surgical. The case reported here raises the problem of the leiomyoma-leiomyosarcoma sequence: are we confronted with degeneration, or is there such a thing as a smooth muscle fibre disease?