Utility of multiple endoscopic techniques in differential diagnosis of gallbladder adenomyomatosis from gallbladder malignancy with bile duct invasion: A case report

BACKGROUND: Gallbladder adenomyomatosis (GAM) is a benign lesion, characterized by thickening of the gallbladder wall and a focal mass, which overlap with the features of gallbladder malignancy. Consequently, differential diagnosis of GAM from gallbladder cancer is difficult and approximately 20% of suspected malignant biliary strictures are postoperatively confirmed as benign lesions. Herein, we report a case in which a preoperative diagnosis of GAM was made by a combination of endoscopic and imaging techniques. CASE SUMMARY: A 40-year-old man was referred to our hospital chiefly for a fever and right upper abdominal pain with dark urine. Enhanced computed tomography showed thickening of the gallbladder wall and a mass in the gallbladder neck with involvement of the hepatic bile ducts, which was suspected to be malignant. Gallbladder malignancy with bile duct invasion was ruled out by subsequent endoscopic examinations, including endoscopic retrograde cholangio-pancreatography, intraductal ultrasound, and SpyGlass. Endoscopic examinations showed a homogeneous hyperechoic lesion with smooth margins of benign bile duct stricture suggestive of inflammatory stenosis of the bile duct. The patient underwent laparoscopic cholecystectomy. GAM was postoperatively diagnosed and confirmed based on the histopathology results, which are consistent with the preoperative diagnosis. Notably, no malignant event occurred in the patient during a 12-mo follow-up period. CONCLUSION: A combination of endoscopic techniques may help in the differential diagnosis of GAM from gallbladder cancer.