Lipomatous tumors are rare among uterine mesenchymal tumors. Due to their rarity, information on the clinical development and histological origin are lacking. We report a pure uterine lipoma and present a review of the relevant literature. We encountered a 72-year-old postmenopausal woman who was referred to our hospital. Computed tomography (CT) and magnetic resonance imaging (MRI) examinations revealed degenerative uterine tumors and a left ovarian cystic tumor with a solid portion. Total hysterectomy and bilateral salpingo-oophorectomy were performed, and postoperative histological examination revealed a uterine lipoma and adenomyosis. The cystic portion was a mucinous cystadenoma, and the solid portion was classified as a Brenner tumor. The postoperative course was uneventful, and the patient was discharged and remained well until follow-up. Our observations suggest that imaging examinations are sufficient for the diagnosis of uterine lipomatous tumors. To the best of our knowledge, the coexistence of a pure uterine lipoma and a mucinous Brenner ovarian tumor has not been documented in the existing literature. The histogenesis of uterine lipomas remains unclear. However, our results, and those from the existing literature, indicate that the mesenchymal stem cells surrounding the perivascular tissue may be implicated, because lipomas of the skin are reported to originate from these cells.