Applied Radiology

Diagnosis

Pseudomyxoma peritonei

Findings

Contrast-enhanced axial computed tomography (CT) images demonstrate a large volume of peritoneal fluid with a mass effect on the bowel, scalloping of the liver edge, and right-sided hydronephrosis. Several surgical clips are present in the right side of the pelvis. A large hiatal hernia, midline ventral abdominal hernia, and pleural effusions are also present.

Discussion

Pseudomyxoma peritonei refers to intraperitoneal accumulation of gelatinous ascites. It occurs secondary to rupture of a well-differentiated mucinous adenocarcinoma of the appendix. Previously it was thought that psuedomyxoma peritonei could also be due to mucinous tumors of the ovary, but now it is thought to be more likely that the ovarian lesions are metastatic.

Patients most commonly present with abdominal pain, distention, weight loss, and often demonstrate new onset of abdominal hernias secondary to mass effect. As the accumulation of mucin progresses, patients may develop bowel obstructions as well as ureteral obstruction.

Imaging findings of pseudomyxoma peritonei include accumulation of low-attenuation fluid through the peritoneum, omentum, and mesentery. Some of the fluid may demonstrate loculations, and cystic structures may be identified on ligaments, such as the falciform and gastrohepatic ligaments. As the gelatinous fluid accumulates, it exerts mass effect on surrounding structures and will often scallop the surface of visceral organs such as the liver and less commonly the spleen. Hernias may also develop as the intraabdominal pressure increases. Ultrasound evaluation reveals echogenic peritoneal fluid and echogenic mucinous intraperitoneal masses. Magnetic resonance imaging (MRI) evaluation will demonstrate low-signal fluid on T1-weighted images and high-signal fluid on T2-weighted images. Cystic implants may also be seen on MRI. As expected, findings of scalloping of the edges of visceral organs as well as abdominal hernias may be appreciated by both ultrasound and MRI.

Pseudomyxoma peritonei is a progressive disease, which is treated with surgical debulking and intraperitoneal chemotherapy. Despite treatment, gelatinous ascites reaccumulates over time with worsening symptoms and is ultimately fatal.

1. Takeuchi M, Matsuzaki K, Yoshida S, et al. Imaging findings of urachal mucinous cystadenocarcinoma associated with pseudomyxoma peritonei. Acta Radiol. 2004:45;348-50.
2. Moran BJ, Cecil TD, et al. The etiology, clinical presentation, and management of pseudomyxoma peritonei. Surg Oncol Clin N Am. 2003:12:585-603.
3. Pickhardt PJ, Rohrmannn CA Jr, Kende AI. Primary neoplasms of the appendix: Radiologic spectrum of disease with pathologic correlation. Radiographics. 2003:23;645-62.