Prevalence of Pancreaticobiliary Maljunction and High Confluence of the Pancreaticobiliary Ducts: True Incidence of Gallbladder Cancer

ABSTRACT Background Although pancreaticobiliary maljunction (PBM) is associated with a high incidence of biliary cancer, it often goes undiagnosed. This means that the true prevalence of PBM and the incidence of biliary cancer are unknown. High confluence of the pancreaticobiliary ducts (HCPBD) may be an intermediate PBM variant, though reports are scarce. In this study, we aimed to determine the true prevalence of PBM and HCPBD and the actual incidence of biliary cancer. Methods We retrospectively analyzed data from adults who underwent cholecystectomy for benign gallbladder disease and compared them to those with gallbladder and bile duct cancers. The common channel (CC) and narrow distal segment (NDS) were measured using magnetic resonance cholangiopancreatography to diagnose PBM and HCPBD. Results PBM and HCPBD were identified in 0.44% and 0.88% of 2046 benign cholecystectomies, 16% and 4.2% of gallbladder cancers, and 1.3% and 3.8% of bile duct cancers, respectively ( p < 0.01). Conclusions The overall prevalence was 0.44%. Combined with national data, the gallbladder cancer incidence in PBM was estimated to be 2.4% over one decade, which is 38‐fold higher than that in the general population. Approximately 1% of the population have HCPBD, which may be a risk factor for biliary cancer.