A rare case of choledochocele associated with pancreas divisum.

Choledochocele, type III choledochal cyst, is a rare abnormality. We report a rare case of choledochocele involving a 15-year-old girl who presented with intermittent episodes of upper abdominal pain. She underwent computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP), which revealed no abnormalities of biliary and pancreatic ducts. Endoscopic retrograde cholangiopancreatography (ERCP) initially suggested a diagnosis of pancreas divisum (PD), and so we failed to diagnose choledochocele at that time. Her condition improved and she was discharged, but she presented again with recurrent episodes of upper abdominal pain. Then, spiral computed tomography with intravenous infusion cholangiography (IVC-SCT) facilitated a diagnosis of choledochocele. The coexistence of choledochocele and pancreas divisum is extremely rare, and it is difficult to diagnose. However, this case suggests that the absence of pancreatitis does not rule out choledochal cysts, and modern imaging techniques, such as IVC-SCT, must be applied in difficult cases.