Xanthogranulomatous cholecystitis masquerading as gallbladder carcinoma

Clinical History

A 55 year old lady presented with recurrent episodes of right hypochondrial pain for the last 5 months. She also complained of gradually worsening jaundice for the last 1 month.

Imaging Findings

Ultrasonography demonstrated cholelithiasis with irregular gall bladder wall thickening. There was associated bilobar intrahepatic biliary radicle dilatation due to biliary obstruction at the level of common hepatic duct. Abdominal CT showed ill-defined gall bladder wall thickening with indistinct fat planes with the adjacent structures. MRI confirmed these findings. An extended cholecystectomy was performed under the tentative diagnosis of gallbladder carcinoma. Intraoperatively, the thickened wall of the gallbladder was found infiltrating into other tissues including gallbladder bed and omentum. An intraoperative frozen section failed to reveal malignant cells. Still a radical chofecystectomy with partial hepatic wedge resection was performed. Postoperative histopathological examination demonstrated sheets of foamy macrophages, plasma cells, lymphocytes, neutrophils, foreign body type giant cells and cholesterol clefts infiltrating the mucosa, muscularis layer and adventitia of gallbladder. The inflammatory process was contiguously infiltrating the hepatic parenchyma and omentum. Microscopic finding confirmed xanthogranulomatous cholecystitis. Thickened gall bladder wall was extensively sampled but no evidence of malignancy was found. Postoperative course of the patient was uneventful, and she has been doing well on follow-up.

Discussion

Xanthogranulomatous cholecystitis (XGC) is a pseudotumoural inflammatory condition of the gallbladder that radiologically simulates gallbladder carcinoma. It is a rare aggressive form of cholecystitis with a reported incidence of 1-4 % in post-cholecystectomy specimen. It is more frequent in women in 5th-6th decades of life. Common predisposing factors include cholelithiasis, obesity, and diabetes mellitus. XGC is characterized by a destructive xanthogranulomatous inflammation of the gall bladder wall, which can be either localized or diffuse in nature. The classical findings of XGC on histological examination include a mixture of ceroid xanthogranulomas with foamy histiocytes, multinucleated foreign-body giant cells, lymphocytes, and fibroblasts. Apparently it results from ruptured Rokitansky-Aschoff sinuses with intramural extravasation of bile leading to macrophage recruitment and activation. Phagocytosis of insoluble bile lipids and cholesterol by the macrophages leads to lipo(xantho)granuloma formation, which subsequently results in fibrosis. This xanthogranulomatous inflammatory process can contiguously infiltrate adjacent organs and thus can be mistaken for malignancy on preoperative imaging or intra-operatively, consequently resulting in extensive surgical resection. Some authors have also attributed this condition partly to a delayed hypersensitivity reaction or a subacute bacterial infection (eg, Klebsiella, Escherichia coli, Proteus mirabilis, Enterobacter and Citrobacter species).

XGC is extremely difficult to suspect preoperatively as it macroscopically resembles gall bladder carcinoma. The affected gall bladder may show diffuse mural thickening or may form a tumour-like focal mass. 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. Lymphadenopathy and biliary obstruction may be allied findings. CT or MR imaging features of XGC and gallbladder carcinoma can overlap substantially, and these entities may not be reliably differentiable. Both diseases may demonstrate gallbladder wall thickening, infiltration of the surrounding fat, hepatic involvement and lymphadenopathy. We herein present a case wherein the clinical and radiological findings of XGC were indistinguishable from gall bladder carcinoma; except for the presence of poorly enhancing hypointense intramural areas on T1-weighted MR imaging. The patient underwent excessive surgical resection, and subsequent histopathological examination confirmed xanthogranulomatous cholecystitis.

Differential Diagnosis List

Final Diagnosis

Xanthogranulomatous cholecystitis

URL:	https://eurorad.org/case/8648
DOI:	10.1594/EURORAD/CASE.8648
ISSN:	1563-4086