Contrast-Enhanced Ultrasound Findings of Peritoneal Polypoid Endometriosis: A Case Report and Literature Review.

Polypoid endometriosis (PEM) is a rare and distinctive variant of endometriosis, with ectopic endometrium presenting as a polypoid appearance. Due to the irregular shape of the mass on imaging, accompanied by obvious blood flow signals and often with elevated tumor marker CA125, it is prone to be misdiagnosed as a malignant tumor. We report a 43-year-old female with a history of ovarian endometriosis, in whom a heterogeneous echo mass was found in the pelvic cavity. The mass, located on the peritoneum and adhered to the omentum majus, had an irregular shape and prominent blood flow signals, complicating the imaging findings. Both contrast-enhanced computed tomography and magnetic resonance examinations identified the mass as a malignant ovarian tumor, whereas conventional ultrasound failed to determine its nature. However, venous contrast-enhanced ultrasound (CEUS) revealed benign characteristics, such as uniform enhancement of the solid portion and slow, consistent regression. The postoperative pathology confirmed that it was PEM. PEM is difficult to diagnose preoperatively due to its rarity, non-specific symptoms, and complex imaging features. This case, by summarizing and analyzing the CEUS image characteristics of peritoneal PEM, fills the gap in this new technology of CEUS, expands the possibilities of non-invasive imaging diagnosis, and reviews the relevant literature published to emphasize its features, pathogenesis, diagnostic methods, and treatment approaches, thereby enhancing the understanding and management of this condition.