[Xanthogranulomatous cholecystitis associated with a suspicious colonic fistula and its spontaneous resolution].

Fistula between the gallbladder and colon is a rare condition. Even more infrequent is spontaneous resolution of the fistula. We encountered a case of cholecystocolic fistula associated with xanthogranulomatous cholecystitis (XGC) that was diagnosed definitively using CT, MRI, and colonoscopy. An 82-year-old woman with no remarkable medical history presented with fever and right hypochondralgia that had continued for 8 days. Abdominal ultrasound showed a hyperechoic area as air in the lumen of the gallbladder with a hypertrophic wall. Contrast-enhanced CT, with the peripheral layer enhanced homogeneously by contrast medium, indicated air in the gallbladder with a thickened wall. Furthermore, MRI and colonoscopy revealed a fistula between the gallbladder and transverse colon strongly suggested. Those findings suggested cholecystocolic fistula associated with XGC. The patient was treated initially by administration of antibiotics, while fasting. Unfortunately, surgical specimens did not show the fistula, thus it was decided that the existence of cholecystocolic fistula with spontaneous resolution were highly suspected by the clinical course and imaging in this patient.