Pancreatoduodenectomy for circumportal pancreas accompanying the retroportal pancreatic duct: a case report and review of the literature.

Circumportal pancreas (CP) is an extremely rare pancreatic fusion anomaly which is usually asymptomatic. This report presents the case of a patient with a tumor in the head of a CP and the retroportal accessory pancreatic duct in the pancreatic tissue behind the portal vein. A 53-year-old male was diagnosed with a nonfunctioning neuroendocrine tumor of the pancreas and resection of the tumor was scheduled. The patient was revealed to have CP on preoperative computed tomography and endoscopic retrograde cholangiopancreatography, which showed the pancreatic tissue encircling the portal vein and the retroportal accessory pancreatic duct. The patient safely underwent pylorus-preserving pancreatoduodenectomy reconstructed with pancreaticogastrostomy.