Intravascular lipoleiomyomatosis: a report of two cases.

Two cases of intravascular leiomyomatosis (IVL) with histologic features of a lipoleiomyoma (LPL) are reported. Both tumors arose from preexisting uterine leiomyomata. One tumor was found incidentally in a uterus removed for leiomyomata. The other tumor extended up the inferior vena cava into the right side of the heart and presented as a cardiac mass. Although LPL is considered to be a benign lesion, IVL recurs in approximately 10% of reported cases, and must be distinguished from low-grade endometrial stromal sarcoma and leiomyosarcoma with vascular invasion. The combination of features in these cases lends support to the theory that IVL may arise by intravascular extension of a preexisting leiomyoma.