OBJECTIVE. The purpose of this study was to determine the potential of CT for distinguishing tuberculous peritonitis from peritoneal carcinomatosis in 135 clinically or pathologically proven cases. MATERIALS AND METHODS. Abdominal CT scans in 135 patients of tuberculous peritonitis (n = 42) and peritoneal carcinomatosis (n = 93) with documented omental, mesenteric, or peritoneal pathology were retrospectively reviewed. CT findings were evaluated in each group of patients for the morphologic appearance of mesenteric or omental abnormalities as well as for visualization of the spleen and liver, the lymph nodes, and ascites. Statistical comparisons using multivariate logistic regression analysis were performed to adjust for the differences in CT findings between the two groups. RESULTS. Mesenteric changes were more commonly seen in patients with tuberculous peritonitis (98%) than in patients with peritoneal carcinomatosis (70%) (p < .01). Micronodules (less than 5 mm in diameter) were noted in approximately one half of patients with tuberculous peritonitis or peritoneal carcinomatosis, but macronodules (greater than or equal to 5 mm in diameter) were much more frequently seen in patients with tuberculous peritonitis (52%) than in patients with peritoneal carcinomatosis (12%) (p < .01). The omentum appeared to be more irregularly infiltrated in peritoneal carcinomatosis patients (p < .01). The thin omental line covering the infiltrated omentum was seen in 13 patients with tuberculous peritonitis but in only four patients with peritoneal carcinomatosis (p < .01). In peritoneal or extraperitoneal masses in patients with tuberculous peritonitis, a low-density center was seen in 18 cases (43%) and calcification was noted in six cases (14%). The prevalences of splenomegaly and splenic calcification were higher in patients with tuberculous peritonitis. Using multivariate analysis, we calculated the sensitivity of CT for predicting tuberculous peritonitis and peritoneal carcinomatosis as 69% and 91%, respectively. CONCLUSION. Although most CT findings that we analyzed overlap these diseases, using a combination of CT findings increased our ability to distinguish tuberculous peritonitis from peritoneal carcinomatosis.
