CT imaging review of uncommon peritoneal-based neoplasms: beyond carcinomatosis

Pathologic involvement of the peritoneum can result from a wide variety of conditions, including both neoplastic and non-neoplastic entities. Neoplastic involvement of the peritoneal ligaments, mesenteries, and spaces from malignant spread of epithelial cancers, termed peritoneal carcinomatosis, is frequently encountered at CT evaluation. However, a host of other more unusual benign and malignant neoplasms can manifest with peritoneal disease, including both primary and secondary peritoneal processes, many of which can closely mimic peritoneal carcinomatosis at CT. In this review, we discuss a wide array of unusual peritoneal-based neoplasms that can resemble the more common peritoneal carcinomatosis. Beyond reviewing the salient features for each of these entities, particular emphasis is placed on any specific clinical and CT imaging clues that may allow the interpreting radiologist to appropriately narrow the differential diagnosis and, in some cases, make an imaging-specific diagnosis.