Fig. 1

a Arterial-phase contrast computed tomography (CT) showing a mildly enhanced lesion in the gallbladder fundus (arrows). b Coronal image revealing that the dilated extrahepatic bile duct (EHBD) (dotted arrows) and the main pancreatic duct (arrow) joining into the EHBD at outside the duodenal wall (arrowheads). c Endoscopic retrograde cholangiopancreatography demonstrating the pancreaticobiliary maljunction