Abstract
Pancreaticobiliary maljunction (PBM) is a congenital anomaly where the pancreatic and bile ducts join outside the duodenal wall, resulting in formation of an elongated common channel. In normal physiology, the sphincter of Oddi regulates the junction between the pancreatic and bile ducts. Individuals with PBM lack this regulatory mechanism resulting in reflux of pancreatic juices into the biliary tract. Activated pancreatic enzymes result in chronic inflammation of biliary tract resulting in choledochal cysts which places patients at risk for eventual development of cholangiocarcinoma. A 45-year-old white male presented with jaundice and dark urine. Laboratory tests showed elevated liver enzymes and bilirubin. Diagnostic imaging revealed anomalous biliary anatomy, a Type 1A choledochal cyst, and a mass in the common hepatic duct. Extrahepatic cholangiocarcinoma was confirmed by ERCP and biopsy, with PET/CT indicating localized disease without distant metastases. Treatment included a biliary sphincterotomy, stone drainage, and stenting. The patient underwent a robotic-assisted bile duct resection, cholecystectomy, hepatic lobectomy, and Roux-en-Y hepaticojejunostomy. The surgical specimen showed an invasive, poorly differentiated adenosquamous carcinoma with perineural invasion, but no regional lymph node involvement. PBM is a rare condition, and its diagnosis and management necessitate a multidisciplinary team, including pancreaticobiliary surgeons, endoscopists, and radiologists. Accurate diagnosis hinges on the team's expertise. Radiologists must be aware of PBM and have a thorough understanding of the associated anatomy and imaging characteristics that may indicate high-risk dysplasia or malignancy.