Association between the confluent form of pancreatic and bile duct and histopathological findings in pancreaticobiliary maljunction: A case series study

Pancreaticobiliary maljunction (PBM) is a congenital anomaly wherein the persistent reflux of the pancreatic juice into the biliary tract induces biliary tract cancer. The prediction criteria for gallbladder carcinogenesis have been reported previously through results obtained from examining carcinogenic and non-carcinogenic cases with the parameters that classified each confluent form in PBM. This study aimed to validate these previous study results and provide new recommendations for gallbladder carcinogenesis prevention. Twenty-four patients with PBM underwent hepaticojejunostomy. The prediction criteria for gallbladder carcinogenesis consist of three elements. The confluent forms that satisfied none or one of the three criteria were defined as a low score group, and those that satisfied two or three were defined as the high score group. Immunohistology and pathological search were performed on the gallbladders' sections in both groups to evaluate chronic inflammation. The cases with dysplasia, positive Ki67 labeling index, and gallbladder cancer were more common in the high score group and tended to have more lymphocyte infiltration. These findings indicate that the degree of inflammation and cell proliferation might be more severe in the high score group than in the low score group. There is a close relationship between the confluent form and the histopathological findings of the gallbladder in patients with PBM. The confluent forms observed in the high score group might have an additional correlation with increased proliferation activity and subsequent malignant transformation of the gallbladder epithelium. •Pancreaticobiliary maljunction (PBM) may induce biliary tract cancer.•This is the first report showing a correlation between the form in PBM and pathological findings of the gallbladder.•We were able to show that PBM has a group with confluent forms with a strong carcinogenic tendency.