Polypoid endometriosis with endometrioid intraepithelial neoplasia mimicking malignancy: a rare case of a postmenopausal pelvic mass.

Polypoid endometriosis is a rare variant characterized by mass-forming endometriosis, often mimicking malignancy. This report describes the case of a postmenopausal woman who presented with an incidental complex adnexal mass and elevated tumor markers. She underwent bilateral salpingo-oophorectomy and mass removal. Frozen section suggested endometriosis with possible serous borderline tumor, prompting staging. Final pathology revealed polypoid endometriosis with areas of endometrioid intraepithelial neoplasia. Polypoid endometriosis may present as a postmenopausal pelvic mass with elevated tumor markers and can contain endometrioid intraepithelial neoplasia.