Xanthogranulomatous Cholecystitis Research Articles

Endoscopic Findings of a Patient Having Cholelithasis in SOMCH, Sylhet, Bangladesh

Introduction: Cholelithiasis is one of the most frequently encountered disease and one of the major causes of abdominal morbidity throughout world [1]. Cholelithiasis is one of the most common and costly of all digestive diseases. Common causes of upper abdominal symptoms are peptic ulcer, acute and chronic gastritis and gallstones. Objective: To assess the endoscopic findings of a patient having cholelithasis in SOMCH. Methods: This was Retrospective Hospital based study conducted at Department of Surgery, Sylhet MAG Osmani Medical College Hospital, Sylhet, Bangladesh from January to December 2022 were (One hundred patients were included). All patients underwent OGD after being diagnosed as having cholelithiasis proved by Endoscopic. All patients above 18 years of age presenting with upper abdominal pain, dyspepsia with or without jaundice diagnosed ultrasonically as cholelithiasis and choledocholithiasis with cholelithiasis were included in the study and patients managed conservatively, patients with primary choledocholithiasis and with asymptomatic gallstones were excluded from the study. Results: Out of 100 subjects evaluated during the study period, 58 were females and 42 males. The most common age group affected was between 31-50 years (65%), followed by less than 30 years of age being 18% and more than 50 years being 17%. It should also be noted the higher rate of incidence (65%) in the age group of 31-50 years. Associated symptoms with cholelithiasis were pain in abdomen, which was observed in all the patients (100%). Of these, 74 patients (74%) presented with chronic upper abdominal pain and 26 patients (26%) presented with acute upper abdominal pain. Remaining 56% of the subjects had positive endoscopic findings. Endoscopic findings were positive in 56 had hiatus hernia, duodinitis, duodenal ulcer or other positive findings. Among patients with positive findings 14 had both oeophagitis as well as gastritis while 12 had both gastritis as well as gastric ulcer. All the 56 patients (100%) underwent surgery. Forty patients (71.4%) underwent laparoscopic cholecystectomy, 14 (25.0%) open cholecystectomy and 2 cholecystostomy for empyema gall bladder. Of the 56 patients 40 patients (71.4%) patient had chronic cholecystitis, 9 patients (16.07%) had acute cholecystitis, 4 patients (7.14%) had carcinoma gall bladder, 2 (3.57%) had xanthogranulomatous cholecystitis and 1(1.78%) had cholesterolosis of gallbladder. Of the 4 patients diagnosed of carcinoma gallbladder, 1 patient had carcinoma confined to muscularis mucosa with negative margins and no metastasis, hence no further surgical management was advised and the rest of the 3 patients had either metastasis or positive margins which were managed as per standard guidelines. Conclusion: Cholelithiasis is commonly seen in females in 4th and 5th decade mainly presenting with abdominal pain and dyspepsia. Endoscopy the most common finding was gastritis, oesophagitis and gastric ulcer in decreasing order. There was no hiatus hernia, duodinitis or duodenal ulcer in our study. Patients presenting with dyspepsia and gall-stones in rural setup should be directly treated surgically. Multiple gallstones are common and Laparoscopic cholecystectomy offers best surgical management with 6.57% of conversion rate to open cholecystectomy, with lesser complications.

Etiology for Cholestatic Jaundice: Bolt from the Blue

Xanthogranulomatous cholecystitis (XGC) is a rare inflammatory disease of the gallbladder (GB) that is characterized by a focal or diffuse destructive inflammatory process. We present a patient with chronic liver disease with portal hypertension who had features of obstructive jaundice due to choledocholithiasis and a palpable mass in the right hypochondrium masquerading as an empyema/carcinoma of the GB. This presentation was preceded by cholestatic jaundice due to acute hepatitis E virus infection.

Gallbladder and biliary pathology: lessons learned from multidisciplinary conference.

The radiologic diagnosis of biliary disease can be challenging due to atypical or delayed presentation, rare or less common entities, and imaging overlap of benign and malignant processes. Establishing a specific diagnosis, when possible, is important to avoid progression of infections to sepsis and multiorgan failure, and for appropriate staging and management in cases of malignancy. Gallstones are the most common biliary disease, and along with stone-related complications, including cholecystitis and choledocholithiasis, constitute the majority of acute biliary pathology. Late and atypical manifestations of acute cholecystitis demonstrate imaging overlap with primary gallbladder cholangiocarcinoma, especially with cases of exuberant inflammatory reaction such as xanthogranulomatous cholecystitis. Additional challenging scenarios related to gallbladder disease, that may be benign or malignant, include adjacent fistulas and lymphadenopathy. Dropped gallstones, especially in atypical locations, may be misdiagnosed as neoplastic. Recurrent cholecystitis after cholecystectomy, whether related to subtotal cholecystectomy or to stumpitis, is another entity that can be confusing to the radiologist with a documented history of cholecystectomy. Inflammatory and autoimmune conditions, such as pseudotumors and IgG4 disease, are a less common but not infrequent cause of diagnostic dilemma. Furthermore, biliary strictures and hepatobiliary cystic lesions can be benign or malignant and could constitute a diagnostic and management challenge. The goal of this manuscript is to present the lessons learned from multidisciplinary conferences on the above entities and suggest tips and pearls to maximize the value of radiologists' contribution to patient management.

Dual-energy CT in differentiating benign gallbladder wall thickening from wall thickening type of gallbladder cancer.

To evaluate the performance of dual-energy computed tomography (DECT) in differentiating non-acute benign from malignant gallbladder wall thickening (GBWT). This prospective study comprised consecutive adults with GBWT who underwent late arterial phase (LAP) and portal venous phase (PVP) DECT between January 2022 and May 2023. The final diagnosis was based on histopathology or 3-6 months follow-up imaging. DECT images in LAP and PVP were assessed independently by two radiologists. The demographic, qualitative, and quantitative parameters were compared between two groups Multivariate logistic regression was performed to determine the association between the aforementioned factors and malignant GBWT. Seventy-five patients (mean age 56 ± 12.8 years, 46 females) were included. Forty-two patients had benign, and 33 had malignant GBWT. In the overall group, female gender (p = 0.018), lymphadenopathy (p = 0.011), and omental nodules (p = 0.044) were significantly associated with malignant GBWT. None of the DECT features differed significantly between benign and malignant GBWT in overall group. In the xanthogranulomatous cholecystitis (XGC, n = 9) vs. gallbladder cancer (GBC) (n = 33) subgroup, mean attenuation value at 140 keV LAP VMI was significantly associated with malignant GBWT [p = 0.023, area under curve 0.759 (95%CI 0.599-0.919)]. DECT-generated quantitative parameters do not add value in differentiating non-acute benign from malignant GBWT. However, DECT may have a role in differentiating XGC from GBC in a selected subgroup of patients. Further, larger studies may be necessary to confirm these findings. In patients with non-acute gallbladder wall thickening in whom there is suspicion of xanthogranulomatous cholecystitis (XGC), DECT findings may allow differentiation of XGC from wall thickening type of gallbladder cancer. Differentiation of benign and malignant gallbladder wall thickening (GBWT) at CT is challenging. Quantitative dual energy CT (DECT) features do not provide additional value in differentiating benign and malignant GBWT. DECT may be helpful in a subgroup of patients to differentiate xanthogranulomatous cholecystitis from gallbladder cancer.

Xanthogranulomatous cholecystitis. A rare case of chronic cholecystitis simulated gallbladder cancer

Xanthogranulomatous cholecystitis. A rare case of chronic cholecystitis simulated gallbladder cancer

A Case of Intracholecystic Papillary Neoplasm with Xanthogranulomatous Cholecystitis

A Case of Intracholecystic Papillary Neoplasm with Xanthogranulomatous Cholecystitis

18F]FDG PET/CT in Benign and Malignant Diseases Involving the Biliary Tract.

Role of FDG PET/CT in evaluation of biliary tract diseases remains relatively unexplored. PET/CT with FDG helps in evaluation of both infective / inflammatory as well as neoplastic diseases as increased glucose utilization is observed in both the conditions. In this article, we describe the spectrum of FDG PET/CT findings in various diseases affecting the biliary tract. Role of FDG PET/CT in neoplastic diseases involving the biliary duct has been described at the time of staging and response evaluation; in characterization of the intrahepatic mass (abscess v/s cholangiocarcinoma). In addition, we have discussed about the false positive FDG uptake along the biliary duct stent, which interfere with scan interpretation. Few of the benign conditions described are Langerhans cell histiocytosis and IgG4 related disease involving the biliary duct and adenomyomatosis and Xanthogranulomatous cholecystitis involving the gall bladder.

Unnecessary Extended Surgical Resection for Xanthogranulomatous Cholecystitis Mimicking Gallbladder Carcinoma: A Case Report

The Xanthogranulomatous Cholecystitis (XGC) is frequently misdiagnosed as Gallbladder Carcinoma (GBC) and usually undergoes an extended radical surgery. Sometimes XGC might have a coexistent GBC. The dilemma still exists concerning the differential diagnosis in clinical practice, and the final diagnosis has to be dependent on the histological examination. This case shows us the diagnostic difficulty of XGC pre-operatively and the resemblance, especially radiological, with GBC, which led to unnecessary extended surgical resection surgery.

Machine learning-based diagnostic model for preoperative differentiation between xanthogranulomatous cholecystitis and gallbladder carcinoma: a multicenter retrospective cohort study.

Xanthogranulomatous cholecystitis (XGC) and gallbladder carcinoma (GBC) share similar imaging and serological profiles, posing significant challenges in accurate preoperative diagnosis. This study aimed to identify reliable indicators and develop a predictive model to differentiate between XGC and GBC. This retrospective study involved 436 patients from Zhejiang Provincial People's Hospital and The Affiliated Lihuili Hospital of Ningbo University. Comprehensive preoperative imaging, including ultrasound, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and blood tests, were analyzed. Machine learning (Random Forest method) was employed for variable selection, and a multivariate logistic regression analysis was used to construct a nomogram for predicting GBC. Statistical analyses were performed using SPSS and RStudio software. The study identified gender, Murphy's sign, absolute neutrophil count, glutamyl transpeptidase level, carcinoembryonic antigen level, and comprehensive imaging diagnosis as potential risk factors for GBC. A nomogram incorporating these factors demonstrated high predictive accuracy for GBC, outperforming individual or combined traditional diagnostic methods. External validation of the nomogram showed consistent results. The study successfully developed a predictive nomogram for distinguishing GBC from XGC with high accuracy. This model, integrating multiple clinical and imaging indicators, offers a valuable tool for clinicians in making informed diagnostic decisions. The findings advocate for the use of comprehensive preoperative evaluations combined with advanced analytical tools to improve diagnostic accuracy in complex medical conditions.

The Many Hidden Faces of Gallbladder Carcinoma on CT and MRI Imaging-From A to Z.

Gallbladder carcinoma represents the most aggressive biliary tract cancer and the sixth most common gastrointestinal malignancy. The diagnosis is a challenging clinical task due to its clinical presentation, which is often non-specific, mimicking a heterogeneous group of diseases, as well as benign processes such as complicated cholecystitis, xanthogranulomatous cholecystitis, adenomyomatosis, porcelain gallbladder or metastasis to the gallbladder (most frequently derived from melanoma, renal cell carcinoma). Risk factors include gallstones, carcinogen exposure, porcelain gallbladder, typhoid carrier state, gallbladder polyps and abnormal pancreaticobiliary ductal junction. Typical imaging features on CT or MRI reveal three major patterns: asymmetric focal or diffuse wall-thickening of the gallbladder, a solid mass that replaces the gallbladder and invades the adjacent organs or as an intraluminal enhancement mass arising predominantly from the gallbladder fundus. The tumor can spread to the liver, the adjacent internal organs and lymph nodes. Depending on the disease stage, surgical resection is the curative treatment option in early stages and adjuvant combination chemotherapy at advanced stages. The purpose of this scientific paper is to fully illustrate and evaluate, through multimodality imaging findings (CT and MRI), different presentations and imaging scenarios of gallbladder cancer in six patients and thoroughly analyze the risk factors, patterns of spread and differential diagnosis regarding each particular case.

CONVERSION TO OPEN CHOLECYSTECTOMY - A SAFE ALTERNATIVE, NOT A FAILURE!

Background: Understanding factors that predict conversion in laparoscopic cholecystectomy (LC) to an open procedure is important as it allows better patient selection, preparation, operating list planning, referral, counseling and lowers the threshold for a safe conversion, thereby minimizing undue prolongation of attempts at laparoscopic completion and inadvertent complications.Methods: Records of 1010 consecutive patients who were taken up for LC, at a tertiary care teaching institute in northern India, were reviewed retrospectively. Preoperative and intraoperative characteristics of patients who underwent a successful LC were compared with those who required conversion to open surgery.Results: The conversion rate was 7.5% (76 patients). The most common reason for conversion was the inability to define the ‘Critical view of safety’ in 48, (63%) of patients. Other reasons included dense peri-cholecystic 9 (12%) and intra-abdominal 8 (11%) adhesions, suspicion of bile duct injury 4 (5%) or malignancy 3 (4%). Prior upper abdominal surgery, intraoperative finding of a contracted and thick-walled gallbladder (GB), empyema GB, Mirizzi’s syndrome, cholecysto-enteric fistula, and a prior endoscopic common bile duct stone clearance were significant predictors of conversion. Xanthogranulomatous cholecystitis was found more commonly (43% vs 5%) in the conversion group.Conclusion: Conversion to an open procedure during LC should always be treated as an integral component of sound judgement to achieve the safest outcome in a particular patient. Due consideration of pre-operative and intra-operative factors predictive of a higher chance of conversion assists pre-operative patient preparation and counseling as well as surgical planning, conduct and mentoring of residents-in-training.

A294 CHOLESTASIS SECONDARY TO XANTHOGRANULOMATOUS CHOLANGITIS: A CASE REPORT

Abstract Background An 86-year-old female presented with four weeks of intermittent abdominal pain, postprandial nausea with an associated 10 lbs weight loss. Initial labs demonstrated a predominantly cholestatic liver enzyme elevation. Imaging revealed a thickened gallbladder with dilated CBD up to 15mm with no calculi, obstruction or pancreatic mass. EUS demonstrated a prominent ampulla with an area of hyperechogenicity, and ERCP was completed with sphincterotomy and biopsy of the ampulla. A cholangiogram showed a prominent common bile duct and a smooth distal taper without filling defects. Tumor markers, ampullary biopsy, and cytology of CBD brushings were negative for malignancy. Repeat ERCP for non-resolving symptoms with an extension of the sphincterotomy, brushings and insertion of a metal stent was completed without improvement in liver enzymes and a standard hepatitis workup returned negative. Her clinical course was further complicated by recurrent gram-negative bacteremia with CT findings of innumerable abscesses or metastasis in the liver. A US-guided targeted liver biopsy revealed large duct periductal tissue expansion by foamy macrophages with admixed neutrophils, eosinophils, plasma cells, and lymphocytes. These features were consistent with xanthogranulomatous cholangitis. We were planning to start ursodiol given the small duct disease however the patient succumbed to recurrent bacteremia and passed away. Aims Review of methods to attain diagnosis of xanthogranulomatous cholangitis. Methods Case Report. Results Diagnosis of xanthogranulomatous cholangitis can be attained from targetted US-guided biopsy, surgical excision, or EUS-guided CBD biopsy. Conclusions Xanthogranulomatous cholangitis is an extremely rare entity described in limited case reports, frequently mimicking neoplastic disease. Pathology is difficult to attain and historically case reports required surgical resections. One recent case reported diagnosis confirmed via EUS-guided FNA of the CBD. In our case, we attained the diagnosis through a targeted liver biopsy. Pathology of xanthogranulomatous cholangitis typically demonstrates foamy histiocytes, lipid-laden macrophages, eosinophils, lymphocytes, plasma cells, and fibrosis indicating xathogranulomas. The pathogenesis is thought to be an extension of xanthogranulomatous cholecystitis in which bile is extravasated into the gallbladder wall through Rokitansky-Aschoff sinuses or ulceration of the mucosa resulting in an inflammation caused by fibroblasts and macrophages as they phagocytose the lipids in bile, resulting in the formation of xanthoma cells. Given the rarity of the disease, there is no guideline on management and a majority of patients reported underwent surgical excision. This case demonstrates the utility of liver biopsy to establish this rare diagnosis, allowing for better detection and subsequently better-studied management. Funding Agencies None

Xanthogranulomatous Cholecystitis - An Intimidating Diagnostic Dilemma - A Case Report

Xanthogranulomatous cholecystitis (XGC) is an uncommon form of chronic cholecystitis[1] characterized by inflammation and infiltration of gall bladder (GB) wall by lymphocytes and multinucleated histiocytic giant cells. There is transudation of bile into gall bladder wall and involvement of the Rokitansky-Aschoff sinuses leading to formation of submucosal abscess and xanthogranulomas.[2] On CECT, they appear as submucosal hypoattenuating nodules and circumferential wall thickening of gallbladder wall, a sign highly specific of XGC.[3]

Clinical implication of the geometric location (fundal end versus cystic ductal end) of gallbladder cancer.

Management of early-stage gallbladder cancer is becoming more important as the rate of early detection is increasing. Although there have been many studies about the clinical implication of the invasion depth or peritoneal/hepatic location of gallbladder cancers, there is no study on the clinical implication of the geometric location of cancer along the longitudinal length of the gallbladder. The location of gallbladder cancer was defined as the geometric center of the primary site of a tumour, which lies on the longitudinal diameter of the surgical specimens. We compared the oncologic outcomes following surgery between gallbladder cancers located on the fundal end and those located on the cystic ductal end. We also analysed patients with stage 1 gallbladder cancer who recurred after surgery. A total of 575 patients with gallbladder cancer were included in this study. Patients with gallbladder cancer on the cystic ductal end had significantly lower rates of recurrence-free survival (P = 0.016) and overall survival (P = 0.023) compared to those with gallbladder cancer on the fundal end. Among 90 patients with stage 1 gallbladder cancer, three patients had a recurrence, all of whom had cystic ductal end gallbladder cancer and showed cystic duct invasion or concomitant xanthogranulomatous cholecystitis in permanent pathology. Gallbladder cancers on the cystic ductal end had worse postoperative oncologic outcomes compared with those on the fundal end.

The Results of Patients with Histopathological Diagnosed Xanthogranulomatous Cholecystitis, a Single-Center Experience

Objective: Xanthogranulomatous cholecystitis (XGC) is a rare and benign gallbladder disorder. Unnecessary or additional surgical interventions were reported secondary to extended inflammation or suspicion of malignancy. This study aimed to examine patients diagnosed with XGC in our clinic. Materials and Methods: The data of patients were recruited who underwent cholecystectomy and diagnosed with XGC. We excluded patients with no radiologic examination, accompanying pancreas, biliary tree, and hepatic cancer. We recruited the data of patients' demographics, clinical symptoms, imaging studies, characteristics of surgery, and postoperative outcomes. Results: The mean age was 57 ±19.1 years, and there were 12 (31%) females. Abdominal pain was found in 38 (97%) patients as a significant complaint. Elective and emergent cholecystectomy were performed in 18 (46%) and 21 (54%) patients, respectively. Open surgery was performed on 17 (44%) patients, and laparoscopic surgery on 22 (56%). The surgery was completed as laparoscopic in 17 (77%) patients. According to radiologic examinations, suspicious gallbladder malignancy was reported in 4 (10%), 8 (20%), and 4 (10%) patients with USG, CT, and MRI, respectively. There was 1 (3%) patient diagnosed with XGC by USG, 4 (10%) by CT, and 1 (3%) by MRI. Common bile duct (CBD) stone was observed in 10 (26%) of 39 patients. Conversion to open surgery was found in 5 (13%) patients. Intraoperative frozen section analysis was performed in 8 (20%) patients. Extended surgery was performed to 7 (17%) patients. Conclusion: Preoperative diagnosis and surgical management of XGC can be challenging. If a surgeon has suspicion of XGC in preoperative period, expert radiologist opinion should be asked, and they should always keep in mind to perform frozen-section examination.

Xanthogranulomatous Cholecystitis. Case Report and Review of Literature.

Xanthogranulomatous cholecystitis (XGC) is a rare but benign form of chronic cholecystitis representing a small proportion of gallbladder disorders and may mimic carcinoma. The present case is of a 59-year-old male that endorsed a six-month history of vague complaints of diarrhea, anorexia, dark urine, yellowing of his eyes, and recent weight loss without prior work up for his symptoms. Laboratory values showed elevated alkaline phosphatase, gamma-glutamyl transferase (GGT), Cancer antigen 19-9, Chromogranin A, and Lactate Dehydrogenase (LDH). Computer tomography (CT) scan revealed annular-like wall thickening in the body of the gallbladder, wall calcifications in the region of the fundus, and cholelithiasis. Magnetic resonance cholangiopancreatography (MRCP) showed focal narrowing at the mid-gallbladder with restricted diffusion and ill-defined enhancement in this region and a few prominent right upper quadrant lymph nodes. Diagnostic laparoscopy revealed a liver lesion that was resected, and frozen analysis was negative for malignancy. The laparoscopic cholecystectomy was converted to an open procedure due to significant scar tissue in the cystic triangle. The final pathology report revealed xanthogranulomatous cholecystitis (XGC) with no evidence of malignancy identified in the gallbladder or liver parenchyma.

Deep-learning models for differentiation of xanthogranulomatous cholecystitis and gallbladder cancer on ultrasound.

The radiological differentiation of xanthogranulomatous cholecystitis (XGC) and gallbladder cancer (GBC) is challenging yet critical. We aimed at utilizing the deep learning (DL)-based approach for differentiating XGC and GBC on ultrasound (US). This single-center study comprised consecutive patients with XGC and GBC from a prospectively acquired database who underwent pre-operative US evaluation of the gallbladder lesions. The performance of state-of-the-art (SOTA) DL models (GBCNet-convolutional neural network [CNN] and RadFormer, transformer) for XGC vs. GBC classification in US images was tested and compared with popular DL models and a radiologist. Twenty-five patients with XGC (mean age, 57 ± 12.3, 17 females) and 55 patients with GBC (mean age, 54.6 ± 11.9, 38 females) were included. The performance of GBCNet and RadFormer was comparable (sensitivity 89.1% vs. 87.3%, p = 0.738; specificity 72% vs. 84%, p = 0.563; and AUC 0.744 vs. 0.751, p = 0.514). The AUCs of DenseNet-121, vision transformer (ViT) and data-efficient image transformer (DeiT) were significantly smaller than of GBCNet (p = 0.015, 0.046, 0.013, respectively) and RadFormer (p = 0.012, 0.027, 0.007, respectively). The radiologist labeled US images of 24 (30%) patients non-diagnostic. In the remaining patients, the sensitivity, specificity and AUC for GBC detection were 92.7%, 35.7% and 0.642, respectively. The specificity of the radiologist was significantly lower than of GBCNet and RadFormer (p = 0.001). SOTA DL models have a better performance than radiologists in differentiating XGC and GBC on the US.

XANTHOGRANULOMATOUS CHOLECYSTITIS – A RARE HISTOLOGICAL VARIANT

Xanthogranulomatous cholecystitis is a rare presentation of chronic cholecystitis, characterized by xanthogranuloma, severe foam cells, and fibrosis. It can be an inducement of difficulty in cholecystectomy. In this case series, we describe four cases of cholecystitis which was diagnosed post-operatively to have xanthogranulomatous inflammation in the gallbladder on histopathological examination.

Deep learning nomogram for preoperative distinction between Xanthogranulomatous cholecystitis and gallbladder carcinoma: A novel approach for surgical decision

The distinction between Xanthogranulomatous Cholecystitis (XGC) and Gallbladder Carcinoma (GBC) is challenging due to their similar imaging features. This study aimed to differentiate between XGC and GBC using a deep learning nomogram model built from contrast enhanced computed tomography (CT) scans. 297 patients were included with confirmed XGC (94) and GBC (203) as the training and internal validation cohort from 2017 to 2021. The deep learning model Resnet-18 with Fourier transformation named FCovResnet18, shows most impressive potential in distinguishing XGC from GBC using 3-phase merged images. The accuracy, precision and area under the curve (AUC) of the model were then calculated. An additional cohort of 74 patients consisting of 22 XGC and 52 GBC patients was enrolled from two subsidiary hospitals as the external validation cohort. The accuracy, precision and AUC achieve 0.98, 0.99, 1.00 in the internal validation cohort and 0.89, 0.92, 0.92 in external validation cohort. A nomogram model combining clinical characteristics and deep learning prediction score showed improved predicting value. Altogether, FCovResnet18 nomogram has demonstrated its ability to effectively differentiate XGC from GBC preoperatively, which significantly aid surgeons in making informed and accurate surgical decisions for XGC and GBC patients.

Preoperative differential diagnosis of xanthogranulomatous cholecystitis and gallbladder carcinoma

Preoperative differential diagnosis of xanthogranulomatous cholecystitis and gallbladder carcinoma