Neoplastic and nonneoplastic conditions of serosal membrane origin: CT findings

Computed tomography (CT) is an important imaging modality for diagnosis and follow-up of neoplastic or nonneoplastic conditions of the serosal membrane. The characteristic CT findings of malignant pleural mesothelioma include unilateral pleural effusion, thickening of the mediastinal pleura, and circumferential and nodular pleural thickening of greater than 1 cm. Malignant peritoneal mesothelioma manifests as a large mass or diffuse peritoneal thickening without a definable mass and is difficult to differentiate from peritoneal carcinomatosis or tuberculosis. The imaging features of primary serous papillary carcinoma of the peritoneum resemble those of peritoneal carcinomatosis; however, the ovary is usually of normal size. The possibility of desmoplastic small round cell tumor should be considered in children or young adults with multiple peritoneal masses and no identifiable primary malignancy. The CT findings of secondary tumors include a variable amount of fluid in the serosal cavity, thickening of the serosal lining (irregular and nodular), and serosal implants. Nonneoplastic conditions manifest as focal or diffuse thickening of the serosal membrane, a variable amount of fluid in the serosal cavity, and a soft-tissue mass at CT. Although the CT findings of some of the conditions overlap, knowledge of the typical findings is helpful in narrowing the differential diagnosis.