Portal Annular Pancreas (PAP): an Underestimated Devil in Pancreatic Surgery—Systematic Review of Literature and Case Report

INTRODUCTION: Portal annular pancreas (PAP) is an anatomic variation due to aberrant fusion of the ventral and dorsal pancreatic buds around the portal vein. In this article, we present a case report with a systematic review of literature of patients undergoing major pancreatic surgery with associated PAP. We also intend to discuss and suggest possible surgical strategies to minimise major postoperative complications. METHODS: A systematic literature search was conducted using the terms “circumportal,” “periportal,” “pancreas,” “annular pancreas,” “portal annular pancreas” and “pancreas anomaly.” All articles describing portal annular pancreas with surgical resection were included. RESULTS: We identified a total of 53 patients of PAP from 29 articles, who underwent pancreatic resection with a median age of 65 years. POPF (postoperative pancreatic fistula) was demonstrated in 42.55% of patients and 34% had CR (clinically relevant)-POPF. Following pancreaticoduodenectomy, pancreatic stump was reconstructed in all patients with either pancreaticojejunostomy or pancreaticogastrostomy. Standard line of pancreatic transection, i.e., division of anteportal portion at the pancreatic neck and stapling of the retroportal process, resulted in 71% incidence of CR-POPF, whereas it was only 16% when extended resection was performed to achieve single pancreatic stump and 12.5% when retroportal portion was sutured or ligated. Amongst distal pancreatic resections, 66% had POPF and 33% developed CR-POPF. CONCLUSION: It is of utmost importance for pancreatic surgeons to diligently look for and identify PAP in the preoperative imaging. Additional imaging in the form of MRCP helps to define abnormal pancreatic ductal anatomy. Surgeons need to be cognisant of pancreatic stump management in patients with PAP to reduce associated higher rates of POPF.