M ZEGHIDI, A BEN TEKAYA, N DALI, L BEN FARHAT, A MANAMANI, L HENDAOUI Radiology department, Mongi Slim hospital of Marsa, Tunis, Tunisia GI15

Xanthogranulomatous cholecystitis (XGC) is an uncommon variant of chronic cholecystitis. The purpose of our case report is to evaluate and to illustrate its sonographic and CT features.

A 46-year-old lady was admitted to our hospital with complaints of right upper quadrant pain for the last two weeks. Up on examination, she was afebrile and had focal tenderness. The white blood cell count was 6, 500/mm 3 with a normal differential count.

The patient underwent an ultrasound examination after fasting for at least 6 hours. Abdominal CT was also performed with axial reconstruction at 5 and 7,5 mm intervals before and after intravenous (IV) administration of a radiocontrast agent.

Ultrasonography demonstrated a distended gallbladder with an irregular, circumferential and partitioned wall thickening (arrow). Additionally, the gallbladder contained cholelithiasis.

CT revealed also multiple intraluminal calculi within the gall bladder. A choledochal stone with dilatation of the common bile duct was present. Abdominal CT showed circumferential hypodense oedematous gall bladder wall thickening with a continuous mucosal enhancement after IV administration of the radiocontrast agent.

Pericholecystic fat planes with adjacent liver were effaced and there was a linear hypodense band surrounding the liver hilum. The patient underwent open cholecystectomy. Histologic examination confirmed the diagnosis of xanthogranulomatous cholecystitis.

Circumferential hypodense gallbldder wall thikening with intraluminal calculi

Gallbladder wall thikening with a continouas mucosal enhancement

Linear hypodense band surrounding the liver hilum Gallbladder and choledocal stones

 Xanthogranulomatous cholecystitis is a rare inflammatory disease of the gallbladder characterized histologically by the infiltration of round cells, lipid- laden histiocytes, and multinucleated giant cells and the proliferation of fibroblasts in the muscle layer [1].  Chronic infection and calculi associated with stasis of bile probably cause the degeneration and necrosis of the wall and the formation of microabscesses. The intramural microabscesses are replaced eventually by xanthogranuloma, and the gallbladder wall may become markedly thickened, with granulomatous changes and severe inflammation [1].

 Xanthogranulomatous cholecystitis represents between 0.7% and 13.2% of gallbladder disease and mainly affects women between 60 and 70 years old. Its importance lies in the fact that clinically and radiologically it can be confused with the prognostically far more serious condition of carcinoma of the gallbladder [2, 3].  Clinical findings on physical examination and the results of laboratory tests do not appear to be of use in differentiating this gallbladder disorder from other more frequent types.

Although gallstones and a thickened and echogenic gallbladder wall are frequent radiologic findings, they are non specific. Three groups of researchers have reported hypoechoic nodules and bands in the gallbladder wall to be the most characteristic findings in the disease[2,4,5].

As with sonography, thickening of the gallbladder wall was also the most frequent CT finding. Chun et al [6] described using CT to reveal intramural hypoattenuated nodules in 1 1 of 1 1 patients with xanthogranulomatous cholecystitis. The CT findings, which have been considered highly suggestive of XGC, include a continuous mucosal enhancement in a thickened gallbladder wall.

This continuous luminal surface enhancement of gallbladder represents preservation of the epithelial layer thus differentiating it from gall bladder carcinoma. Presence of hypo-attenuating mural nodule or hypodense band around the gall bladder represents lipid-laden inflammatory cell accumulation, or necrosis or abscess formation in XGC.

Adjacent fat planes and adjoining viscera such as liver, duodenum, omentum, and colon may be infiltrated. XGC can also result in fistulas and/ or abscess formation. Uchiyama et al in their study of 32 cases concluded that CT features of the enhanced continuous mucosal line in a thickened GB wall, together with gallstones in a patient with chronic GB disease are highly suggestive of XGC [7,8].

Xanthogranulomatous cholecystitis diagnosis still remains difficult and these ultrasonographic and CT findings are highly suggestive of its preoperative diagnosis. The main differential diagnosis is gallbladder adenocarcinoma.

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6.Chun KA, Ha HK, Yu ES, et al. Xanthogranulomatous cholecystitis: CF features with emphasis on differentiation from gallbladder carcinoma. Radiology 1997;203: Uchiyama K, Ozawa S, Ueno M, Hayami S, Hirono S, Ina S, et al. Xanthogranulomatous cholecystitis: the use of preoperative CT findings to differentiate it from gallbladder carcinoma. J Hepatobiliary Pancreat Surg 2009;16: Shuto R, Kiyosue H, Komatsu E, Matsumoto S, Kawano K, Kondo Y, et al. CT and MR imaging findings of xanthogranulomatous cholecystitis: correlation with pathologic findings. Eur Radiol 2004;14:440-6.