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

Abstract

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.

Keywords: endometriosis; ovarian malignancy; polypoid endometriosis; venous contrast-enhanced ultrasound.

Figure 1

(A) Multiple circular anechoic areas (yellow arrows) are observed within the lump, with hypoechoic areas seen around the periphery (green arrows); (B) Coarse, branch-like blood flow signals are visible both around and within the mass (white arrows); (C and D) Following the injection of contrast medium, the mass enhances in a “vesicle-like” pattern from the center (yellow arrow). The remaining parenchyma shows uniform and equal enhancement, peaking at 25 seconds. Numerous regular, circular non-perfusion areas are visible inside, and a “black margin” of fibrosis (red arrow) is seen at the periphery. Enhancement gradually subsides evenly and slowly by two minutes and 14 seconds. At two minutes and 30 seconds during the regression phase, thick, straight blood vessels are visible at the edge of the mass; (E) CT imaging reveals multiple pelvic masses and nodules; (F) MRI shows an intrapelvic cystic solid mass; (G) Intraoperative view of a pinkish-white mass with multiple purple-blue nodules on the surface; (H) Intraoperative pathology reveals a variety of endometrial glands, endometrial stromal cell proliferation, and disordered arrangement.