Magnetic resonance imaging characteristics of polypoid endometriosis and review of the literature

Abstract

Aim: Polypoid endometriosis is a rare variant of endometriosis and may mimic malignancy. The purpose of this study is to evaluate magnetic resonance (MR) imaging characteristics of polypoid endometriosis for the differential diagnosis with malignancy. Methods: MR imaging findings of four histologically proven polypoid endometriosis were retrospectively evaluated with the review of the literature. Results: All polypoid endometriosis exhibited high signal intensity on T2-weighted images reflecting abundant dilated endometrial glands. Peritoneal lesions were surrounded by low signal intensity rim represented the "black rim sign" reflecting endometriotic fibrous adhesion. Two cases arising from endometriotic cysts showed transmural extension (peritoneal extension and myometrial infiltration). Endometriotic hemorrhagic foci were demonstrated in four lesions as high signal intensity on T1-weighted images and/or susceptibilityinduced signal voids on susceptibility-weighted MR sequence. Diffusion-weighted images showed high signal intensity with relatively high apparent diffusion coefficient (ADC) due to T2 shine-through effect but no diffusion restriction, and dynamic contrast-enhanced (DCE) MR imaging showed gradually increasing contrast-enhancement pattern like benign pathologies. Conclusions: Polypoid endometriosis may mimic malignancy; however, black rim sign may be a characteristic MR imaging finding for the peritoneal lesions, and no diffusion restriction and gradually increasing contrast-enhancement pattern may reflect its benign nature.

Polypoid Endometriosis, a Benign Tumor with Perplexing Radiologic Features: A Case Report

“…However, few recent imaging studies help us to narrow the diagnosis. According to Takeuchi et al [6], polypoid endometriosis showed high signal intensity on T2-weighted images. Peritoneal lesions were associated with pelvic endometriosis and peripheral low-intensity rims were observed as "black rim sign" which is also noticed in this case [6].…”

“…Many radiologic findings are suggested to help to make the differential diagnosis of polypoid endometriosis, but a histopathologic exam of the specimen obtained through surgery is still crucial and the only way to rule out malignancy [6].…”