Uterus-like mass in the left broad ligament misdiagnosed as a malformation of the uterus: a case report of a rare condition and review of the literature.

OBJECTIVE

To describe a rare extrauterine mass of an unknown origin that was composed of smooth muscle with a central cavity lined by endometrium, which resembled a uterus.

DESIGN

Case report.

SETTING

Academic teaching hospital.

PATIENT(S): A 17-year-old girl with severe dysmenorrhea was found to have a uterus-like mass composed of smooth muscle and lined by endometrium in the left broad ligament.

INTERVENTION(S): Abdominal surgery.

RESULT(S): The mass was successfully removed surgically, and her dysmenorrhea resolved. Histopathological examination revealed that the uterus-like mass was composed of smooth muscle with a cavity lined by endometrial glands and stroma.

CONCLUSION(S): The histogenesis of a uterus-like mass is theorized to be a Müllerian system anomaly, metaplastic change, and/or heterotopia. We believe metaplasia is the most likely cause in this case. Alhough rare, it should be considered in the differential diagnosis of dysmenorrhea of uncertain etiology.