Gallbladder carcinoma associated with occult pancreatobiliary reflux in the absence of pancreaticobiliary maljunction

We herein report a case of gallbladder carcinoma associated with occult pancreatobiliary reflux (PR) in the absence of pancreatobiliary maljunction. A 67‐year‐old woman was referred to our hospital for the evaluation and treatment of a gallbladder tumor. Ultrasonography and computed tomography showed a nodular lesion in the fundus of the gallbladder, indicating the possibility of a gallbladder carcinoma. Endoscopic ultrasonography showed the nodular tumor and thickness of the surrounding epithelium. Endoscopic retrograde cholangiopancreatography revealed a normal pancreaticobiliary junction without the common channel and a slight dilatation of the common bile duct (15 mm in diameter). An open cholecystectomy and partial resection of the liver bed of the gallbladder with regional lymphadenectomy was performed. A C‐tube was inserted from the cut end of the cystic duct into the common bile duct to prevent bile stasis. Biliary amylase and lipase levels sampled in the gallbladder were 2604 IU/l and 775 IU/l, respectively. Biliary amylase level in the bile collected from the C‐tube in the common bile duct was 119 550 IU/l on postoperative day (POD) 6 and 22 265 IU/l on POD 12. These observations suggested that PR was present in this patient. The histopathological findings of the resected specimen showed a well‐differentiated adenocarcinoma of the gallbladder with invasion to the muscle layer and no metastasis of the resected lymph nodes. A high index of nuclear staining for MIB‐I in the cancer cells (about 10%) was exhibited, and a few cells in the normal epithelium also stained positive.