Benign metastasizing leiomyoma: metastasis to rib and vertebra.

Benign metastasizing leiomyoma is very rare and characterized by the presence of pelvic, peritoneal, nodal, or pulmonary nodules in women with a history of uterine leiomyomas. We report a case of benign metastasizing leiomyoma in a 30-year-old woman who had undergone a prior myomectomy due to uterine cellular leiomyoma 3 years earlier. The patient had a mass on the right sixth rib and 2 masses in the sixth thoracic vertebra. Pathologically, these masses were diagnosed as cellular leiomyomas. Estrogen and progesterone receptors were both positive in the metastatic tumors as well as in the uterine leiomyomas. The diagnosis of benign metastasizing leiomyoma can only be made after careful examination of the primary tumor to exclude small foci of malignant change.