Embryological etiology of pancreaticobiliary system predicted from pancreaticobiliary maljunction with incomplete pancreatic divisum: a case report

BACKGROUND: The genesis of the “complex type” classification of pancreaticobiliary maljunction (PBM) is unclear, and the pancreaticobiliary anatomy is also varied according to each case. We encountered a patient with PBM and incomplete pancreatic divisum (PD). We herein discussed about the embryological etiology of pancreaticobiliary system predicted from PBM with incomplete PD. CASE PRESENTATION: A 67-year-old man was found to have a dilatation of the common bile duct (CBD) during a medical examination at 62 years of age. The dilatation of the CBD subsequently progressed, and he was admitted to our hospital for surgical treatment. Magnetic resonance cholangiopancreatography revealed a dilatation from the common hepatic duct to the middle bile duct with PBM. Endoscopic retrograde cholangiopancreatography from the papilla of Vater revealed the pancreatic main duct via the pancreatic branch duct, and PBM with dilatation of the CBD and incomplete PD were revealed. We performed an extrahepatic bile duct resection and hepaticojejunostomy because of high risk of malignant transformation. Taping and transection of the bile duct without dilatation on the pancreatic side were performed, and thereafter, two orifices of the common channel and ventral pancreatic duct were ligated. The level of amylase in the bile was 7217 IU/L, and a histological examination of the CBD showed an inflammatory change of CBD, not a malignant transformation. CONCLUSION: It is somewhat easy to identify the pancreatobiliary anatomy when the cause of embryology of both PBM and PD is thought to be an abnormal embryology of the ventral pancreas.