Leiomyosarcoma arising in a lipoleiomyoma.

A leiomyosarcoma arising in a uterine lipoleiomyoma is described in a 70-year-old woman. The tumor measured 11 cm and was located in the corpus uteri. It was composed of a mixture of firm, pale tan, whorled tissue and soft, white or hemorrhagic areas. Histologically, the firm tissue was a mixture of bland smooth muscle, fat and fibrous tissue, whereas the soft areas showed a malignant spindle cell tumor with smooth muscle differentiation. Pure sarcoma similar to the malignant portion of the lipoleiomyoma had metastasized to the vaginal wall.