Clinical

Most neoplastic processes of the peritoneum are secondary to metasteses. Rarely a primary mesothelioma may arise and has the same risk factors for developing as pleural mesotheliomas, namely asbestos exposure. Intraperitoneal seeding of metasteses occurs when tumor cells, generally adenocarcinomas, become freely floating in ascitic fluid and implant on the walls of the peritoneum. Ovarian and stomach carcinomas are the most common source of peritoneal metastases. The most common sites of implantation are: the pouch of Douglas; in the RLQ, the lower end of the small bowel mesentary; in the LLQ, along the superior sigmoid mesocolon and colon; the right paracolic gutter lateral to the cecum and ascending colon; the greater omentum. Metastatic peritoneal disease usually produces large volume ascites and the diagnosis is often made by cytological examination of aspirated fluid.

Radiological findings

Metastatic serosal implants cause an intense desmoplastic reaction that appears as a characteristic retraction of the surrounding bowel folds. Separation of intestinal loops by ascites (peaking), mesenteric masses, nodular impressions, and angulated segments of bowel may also be seen in the context of peritoneal metastases.