leiomyoma benign metastasizing leiomyoma UMLS:C1511090 MONDO:0022560 MEDGEN:307261 A rare disorder that affects women with a history of uterine leiomyoma, which is found to metastasise within extrauterine sites.The disease develops as a proliferation of multiple nodules composed of smooth muscle cells.The most frequent site of metastasis is the lungs, although other areas may also be affected as well, including some atypical locations, e.g. the heart or spinal cord.