# Anomalous pancreaticobiliary junction (pancreaticobiliary maljunction)

Source: https://onco.cc/terms/anomalous-pancreaticobiliary-junction/  
OnCo record `anomalous-pancreaticobiliary-junction` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A birth variation in which the bile duct and pancreatic duct join outside the wall of the bowel, so pancreatic juice flows back up into the bile ducts and gallbladder and irritates their lining for life. It carries a high risk of gallbladder cancer, and removing the gallbladder is advised once it is found.

## Summary

In pancreaticobiliary maljunction the two ducts unite outside the duodenal wall to form a long common channel not controlled by the sphincter of Oddi, allowing reflux of pancreatic enzymes into the biliary tree; it often coexists with a choledochal cyst, and Cancer Research UK lists both as congenital risk factors for gallbladder cancer, quoting about seven times the risk for the maljunction from a meta-analysis of case-control studies (Deng 2011). It is usually diagnosed on MRCP by measuring the common channel and the narrow distal segment. In a 2025 Japanese MRCP series the maljunction was found in 0.44 percent of 2,046 benign cholecystectomies but in 16 percent of gallbladder cancers and 1.3 percent of bile duct cancers; a milder variant, high confluence of the pancreaticobiliary ducts, was present in about 1 percent of the population and 4.2 percent of gallbladder cancers. Combining prevalence with national cancer data, the authors estimated a 2.4 percent ten-year incidence of gallbladder cancer with the maljunction, 38 times the general population (Shirai 2025). That figure is the argument for removing the gallbladder, and a dilated bile duct where present, once the anomaly is found; Cancer Research UK lists the maljunction and choledochal cysts among the congenital risk factors and notes most people with these conditions develop symptoms in childhood, some only as adults.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: Pancreaticobiliary maljunction; PBM; APBDJ; Anomalous union of the pancreaticobiliary ducts; High confluence of the pancreaticobiliary ducts
- Tags: gallbladder; biliary

## Sources

- Shirai, J Hepatobiliary Pancreat Sci 2025: prevalence of pancreaticobiliary maljunction and gallbladder cancer incidence: https://doi.org/10.1002/jhbp.12187
- CRUK: gallbladder cancer risk factors (professional): https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/gallbladder-cancer/risk-factors
- CRUK: risks and causes of gallbladder cancer: https://www.cancerresearchuk.org/about-cancer/gallbladder-cancer/risks-causes

## Connected records

- cancers: [Biliary tract cancer (cholangiocarcinoma)](https://onco.cc/cancers/cholangiocarcinoma/), [Gallbladder cancer](https://onco.cc/cancers/gallbladder/)

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