Polypoid endometriosis of the ovary mimicking ovarian carcinoma dissemination: a case report and literature review.

Polypoid endometriosis is a rare type of endometriosis. We report a case of polypoid endometriosis of the ovary mimicking ovarian carcinoma with peritoneal dissemination. Computed tomography and magnetic resonance imaging showed a left ovarian endometriotic cyst containing several nodules in the cystic wall that displayed enhancement, and pelvic nodules on the right ovary. A preoperative or intraoperative diagnosis to avoid the unnecessary extended operation is important for such disease. Retrospective magnetic resonance imaging analysis identified a peculiar finding for polypoid endometriosis: all solid nodules had a round and smooth shape and displayed a low-signal-intense marginal edge on T2-weighted images, suggesting that this is an important finding for differentiating polypoid endometriosis from ovarian carcinoma arising from endometriosis.