Introduction/Background Uterine leiomyomas are the most common type of benign smooth muscle tumors of the genital organs in reproductive age. Benign metastasizing leiomyoma (BML) is a rare disorder that affects women with a history of uterine leiomyoma, which can find in extrauterine sites, most common in the lung. Because, it is a rare entity, most studies about this issue are case reports, which makes the comprehension difficult to understand the pathological behavior and the most adequate therapeutic approach.

Methodology This work reports two cases of BML in postmenopausal women, previously hysterectomized. The first was 62 years old, was multiple small peritoneal nodules with aspect of carcinomatosis and the second, 59 years old, has a malignant mesenchymal neoplasm in gluteus muscle, whose staging revealed a large solid adnexal mass suspicious for ovarian cancer.

Results Both were submitted to laparotomy for resection the lesions, and the anatomopathological examination showed multiple nodules composed of smooth muscle cells with morphological aspect similar with leiomyoma. In contrast to the knowledge that benign tumors do not metastatize, the term BML is used to describe the presence of histologically benign smooth muscle tumor outside of uterus. It has been suggested that BML is originated by dissemination of uterine primary lesion through lymphovascular pathway, peritoneal seeding by implant and proliferation of fragments of uterine leiomyoma after surgery, or celomic metaplasia mediated by hormone-sensitive proliferation.

Conclusion Despite most cases has a history of prior surgery (myomectomy or hysterectomy), the description of cases of women without a history of myoma surgery, which raises doubts about the hypothesis of lymphovascular dissemination due to former surgery. Options for BML treatment include observation, surgical resection of nodules, administration of progesterone, selective estrogen receptor modulators, aromatase inhibitor and gonadotropin releasing hormone agonists. In postmenopausal women, BML could be mistaken for metastatic cancer.