A case of xanthogranulomatous cholecystitis preoperatively diagnosed with contrast-enhanced ultrasonography

We report a case of xanthogranulomatous cholecystitis (XGC) that was diagnosed preoperatively by means of ultrasonography (US) with the contrast-enhancement agent Sonazoid after a false-positive result had been obtained with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET). A 69-year-old woman was admitted because of right upper quadrant pain. Blood tests revealed a serum CA19-9 level of 749.8 IU/L. Computed tomography (CT), US, and magnetic resonance imaging of the abdomen showed abnormal thickening of the gallbladder wall but no stones. The border between the gallbladder and the liver was unclear. FDG-PET revealed a lesion with increased uptake of tracer in the gallbladder wall. The thickness of the lesion was similar to that on CT. We suspected gallbladder carcinoma with hepatic invasion. To confirm the tentative diagnosis, we performed US with the contrast-enhancement agent Sonazoid. The gallbladder wall was homogeneously enhanced in the early vascular phase and remained enhanced for 90 seconds. Enhancement of the gallbladder wall was smooth and regular. The border between the gallbladder and liver was clear and smooth. On the basis of these examinations, we diagnosed chronic cholecystitis (XGC suspected), not gallbladder carcinoma. At surgery, the gallbladder wall was observed to be extremely thick because of severe inflammation, and cholecystectomy was performed. XGC was diagnosed on intraoperative pathological examination. Histopathological examination showed XGC, severe proliferative fibrosis with formation of multiple yellow-brown intramural nodules, and foamy histiocytes without malignant cells. In conclusion, the present case of XGC was diagnosed preoperatively with contrast-enhanced US after a false-positive result had been obtained with FDG-PET. Contrast-enhanced US can thus play important roles in diagnosing gallbladder disease and selecting treatment.