Intramural venous leiomyosarcomas.

Five cases of intramural venous leiomyosarcomas are described. Only one was localized in the inferior vena cava, the classic site; the other four cases were situated in smaller veins, namely, the short and long saphenous veins, the external jugular vein, and a superficial vein at the back of the hand. Light and, in two cases, electron microscopy, as well as immunohistochemical examinations for factor VIII, helped to establish the diagnosis. The fate of these cases indicates that size and localization are the main determining factors of outcome, whereas the level of mitotic activity is informative only if it is high. Small tumors in superficial veins that are detected early may have an excellent prognosis, even after limited removal of the tumor.