Uterine leiomyomas are the most common form of gynaecological tumours, and are exclusively benign. Only a few are associated with sarcomatous change. It is therefore important for the radiologist to be familiar with their range of appearances on magnetic resonance imaging (MRI) scans to distinguish them from other significant uterine pathologies, such as ovarian neoplasms, that require different management strategies. Here, the authors present the case of a 37-year-old Han woman, gravida 2, para 1 (cesarian section in 1996), who presented with a two-month history of lumbosacral swelling and pain. Physical examination revealed a pelvic mass and she was admitted with the presumptive diagnosis of an ovarian neoplasm. Laparotomy revealed multiple degenerated neoplasms that were benign in appearance, which was pathologically confirmed. A literature review was conducted to explore the natural history of uterine leiomyomas and their underlying etiopathogenesis. The optimal imaging modalities are also defined in the report, which enable the correct preoperative diagnosis to be made in order to optimize the care of women by multiple uterine leiomyomas.