A case of sigmoidal mesenteric lipoma with preoperative diagnosis of ovarian tumor: A case report.

Mesenteric lipomas are rare tumors, with fewer than 50 reported cases. A 42-year-old woman with no significant medical history was referred to our hospital for surgical removal of submucosal myoma and a left ovarian tumor that was diagnosed at a different clinic. Preoperative magnetic resonance imaging findings suggested a differential diagnosis of fibroma, Brenner's tumors, and mature teratomas; however, the intraoperative findings showed a sigmoidal mesenteric tumor adherent to the left ovary. Pathological examination revealed degenerated adipose tissue, and the patient was diagnosed with sigmoidal mesenteric lipoma. When a degenerated sigmoidal mesenteric lipoma is adherent to the ovary, it must be differentiated from an ovarian tumor.