Xanthogranulomatous cholecystitis: diagnostic performance of CT to differentiate from gallbladder cancer

To retrospectively evaluate CT findings of xanthogranulomatous cholecystitis (XGC) and to measure diagnostic performance for distinguishing it from gallbladder (GB) cancer.

Our institutional review board approved this retrospective study. Three blinded radiologists, first independently and then in consensus, retrospectively evaluated postcontrast CT images of 35 patients with histopathologically proved XGC and GB cancer, all of whom subsequently had cholecystectomy. These included 18 patients with XGC (13 male, 5 female; age range, 35-84, mean 63 years) and 17 with GB cancer (6 male, 11 female; age range, 45-95, mean 69). Differences in CT findings between XGC and GB cancer and diagnostic performances for each CT finding were calculated. Sensitivity, specificity, and accuracy were calculated for each radiologist and observer performance was also determined by receiver-operating-characteristic curve analysis.

Five CT findings showed significant differences between XGC and GB cancer. Sensitivity, specificity, and accuracy of each finding for the differentiation of XGC were 89%, 65%, 77% with diffuse GB wall thickening, 67%, 82%, 74% with a continuous mucosal line, 61%, 71%, 66% with intra-mural hypo-attenuated nodules, 72%, 77%, 74% with absence of macroscopic hepatic invasion, and 67%, 71%, 69% with absence of intra-hepatic bile duct dilatation, respectively. When at least three of these five CT findings were observed in combination, sensitivity, specificity, and accuracy were 83%, 100% and 91%, respectively. Sensitivities, specificities and Az values for the differentiation of XGC from GB cancer were 83%, 88%, 0.94 for reader 1, 78%, 88%, 0.93 for reader 2, and 78%, 82%, 0.84 for reader 3.

The combination of three of the five CT findings that are common with XGC can provide excellent accuracy for the differentiation of XGC and GB cancer.