There have also been reports of malignant transformation of tumors thought to be ULs into uterine leiomyosarcoma [5], and there are also reports that mutations in UL driver gene MED12 are also found in uterine leiomyosarcomas [6]. The definitive diagnosis of UL and uterine leiomyosarcoma is made by histopathologic diagnosis, but the most useful clinical differentiation is based on the appearance of high-signal areas and postmenopausal enlargement or rapid enlargement on magnetic resonance imaging (MRI) [7]. Here, MED12 is linked to leiomyosarcoma.