Peritoneal Calcification: Causes and Distinguishing Features on CT

OBJECTIVE: We undertook this study to determine the causes of peritoneal calcification seen on CT and to investigate which CT features distinguish benign from malignant peritoneal calcification. MATERIALS AND METHODS: Seventeen patients with peritoneal calcification were identified through retrospective review of reports from 74765 abdominopelvic CT examinations performed during a 7-year period. We determined the cause of peritoneal calcification by examining medical and histopathologic records. Calcification morphology was classified as nodular or sheetlike on the basis of the consensus interpretation by two independent radiologists. The radiologists also recorded the presence or absence of associated soft-tissue components or lymph node calcification. The association between the CT findings and the cause of calcification was assessed using chi-square analysis. RESULTS: Peritoneal calcification was due to peritoneal dialysis (n = 4), prior peritonitis (n = 3), cryptogenic origin (n = 1), or peritoneal spread of ovarian carcinoma (n = 9). Sheet-like calcification was more common in patients with benign calcification (seven of eight patients) than in those with malignant calcification (two of nine patients, p < 0.05). Nodal calcification was seen only in patients with malignant calcification (five of nine patients vs none of eight, p < 0.05). CONCLUSION: Common causes of peritoneal calcification are dialysis, prior peritonitis, or ovarian cancer; sheetlike calcification indicates a benign cause, whereas associated lymph node calcification strongly suggests malignancy.