Objective: The purpose of this study was to determine the utility of CT in distinguishing peritoneal tuberculosis (PT) from peritoneal carcinomatosis (PC).
Materials and methods: CT scans were retrospectively reviewed in 19 patients known to have PT and compared with scans in 19 patients known to have PC. CT images were evaluated for thickening (smooth versus irregular), enhancement, presence of nodules, and site of involvement on the parietal peritoneum. The existence of omental caking, nodules, and smudged patterns in the omentum, mesentery, and gastrocolic ligament was noted. The presence, distribution, and loculation of ascites were also evaluated.
Results: Ascites was present in all cases of PT and PC, loculated in 10 cases (PT = 4, PC = 6), and located in the greater peritoneal sac (PT = 15, PC = 10) or in the greater and lesser sacs (PT = 4, PC = 9). Slight smooth thickening and pronounced enhancement of the parietal peritoneum were seen in 15 of 19 PT patients and in 5 of 19 PC patients (p<0.001), whereas irregular thickening was found in only 9 of 19 PC patients (p <0.001). Peritoneal nodules were present exclusively in PC (7/19) (p <0.01). The sites of the parietal peritoneum involvement were the pelvic (PT = 9, PC = 3) (p <0.05), paracolic gutters (PT = 5, PC = 6), juxtadiaphragmatic (PT = 0, PC = 9) (p <0.001), and perihepatic (PT = 6, PC = 8) regions. Omental cakes were found in 4 of 19 PT and in 7 of 19 PC patients. The smudged pattern was the most common abnormality in the omentum (PT = 9/19, PC = 11/19), gastrocolic ligament (PT = 5/19, PC = 11/19) (p <0.01), and mesentery (PT = 7/19, PC = 11/19). Isolated and discrete well defined nodules were exclusively found in the mesentery (PT = 5/19, PC = 3/19).
Conclusion: The most useful CT findings for distinguishing PT from PC were observed in the parietal peritoneum. The presence of a smooth peritoneum with minimal thickening and pronounced enhancement suggests PT, whereas nodular implants and irregular peritoneal thickening suggest PC.