- Email: [email protected]
Portal Annular Pancreas With Retroportal Pancreatic Duct Diagnosed With Endoscopic Ultrasound
ELECTRONIC IMAGE OF THE MONTH Portal Annular Pancreas With Retroportal Pancreatic Duct Diagnosed With Endoscopic Ultrasound Evangelos Kalaitzakis*,‡ and Henrik Thorlacius‡ *Endoscopy Unit, Digestive Disease Center, Copenhagen University, Hospital Bispebjerg, University of Copenhagen, Copenhagen, Denmark; ‡Endoscopy Unit, Department of Gastroenterology, Skåne University Hospital, University of Lund, Malmö, Sweden
36-year-old woman was referred for an endoscopic ultrasound (EUS) to exclude microlithiasis as a cause of recurrent acute pancreatitis. She had experienced 2 episodes of acute pancreatitis with an interval of 10 years. Diagnostic work-up (ie, a full blood count, serum electrolytes including calcium, liver function tests, and triglycerides, as well as a magnetic resonance cholangiopancreatography and an upper gastrointestinal endoscopy with duodenal biopsies), had not shown any cause. Physical examination was normal. She had irritable bowel syndrome but was otherwise healthy. Pancreaticobiliary EUS showed a normal nondilated common bile duct and normal gallbladder without stones, sludge, or microlithiasis. Although the pancreatic parenchyma appeared normal, the portal vein was encased by pancreatic tissue and the main pancreatic duct (MPD) had a retroportal course (Figure A and Video A). These findings were confirmed in a pancreatic-protocol computed tomography scan, which, after an oblique axial reconstruction, showed a normal, nondilated MPD posterior to the portal vein (Figure B and Video B). The patient was considered to have recurrent idiopathic pancreatitis. The diagnosis of portal annular pancreas with retroportal main pancreatic duct also was made but it was regarded as incidental. Portal annular pancreas is a congenital pancreatic variant in which the uncinate process encases the portal vein, extending to the dorsal surface of the body of the
A
pancreas. Three types of portal annular pancreas have been described: type I in which the MPD is located posterior to the portal vein (as in this case), type II in which type I is associated with pancreas divisum, and type III in which MPD runs anterior to the portal vein.1 Although portal annular pancreas is not associated with an increased risk of pancreaticobiliary disease per se, it may be misdiagnosed as a mass or tumor encasement of the portal vein.2 Its prevalence is thought to be 2.4%, but it has been reported to be an incidental finding during or after pancreatic surgery in half of the reported cases to date, suggesting a low level of awareness or that it may not be recognized readily.3 This could, possibly, explain why the condition was not recognized at magnetic resonance cholangiopancreatography before referral to our institution. However, patients with unrecognized portal annular pancreas undergoing pancreatic surgery for other reasons have been reported to have a risk of 46.7% of postoperative pancreatic fistula.3 The imaging features of portal annular pancreas, in particular those at transaxial tomographic scanning, have been described,4 and we present a case of portal annular pancreas diagnosed by EUS.
References 1.
Joseph P, Raju RS, Vyas FL, et al. Portal annular pancreas. A rare variant and a new classification. JOP 2010;11:453–455.
2.
Leyndecker JR, Baginski SG. Complete pancreatic encasement of the portal vein (circumportal pancreas): imaging findings and
Clinical Gastroenterology and Hepatology 2015;13:e175–e176
ELECTRONIC IMAGE OF THE MONTH, continued implications of a rare pancreatic anomaly. J Comput Assist Tomogr 2008;32:61–64. 3.
Harnoss JM, Harnoss JC, Diener MK, et al. Portal annular pancreas. A systematic review of a clinical challenge. Pancreas 2014;43:981–986.
4.
Gonoi W, Akahane M, Akai H, et al. Retroportal main pancreatic duct with circumportal pancreas: radiographic visualization. Clin Imaging 2011;35:442–446.
e176
Conflicts of interest The authors disclose no conflicts. Most current article © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2015.04.026
36-year-old woman was referred for an endoscopic ultrasound (EUS) to exclude microlithiasis as a cause of recurrent acute pancreatitis. She had experienced 2 episodes of acute pancreatitis with an interval of 10 years. Diagnostic work-up (ie, a full blood count, serum electrolytes including calcium, liver function tests, and triglycerides, as well as a magnetic resonance cholangiopancreatography and an upper gastrointestinal endoscopy with duodenal biopsies), had not shown any cause. Physical examination was normal. She had irritable bowel syndrome but was otherwise healthy. Pancreaticobiliary EUS showed a normal nondilated common bile duct and normal gallbladder without stones, sludge, or microlithiasis. Although the pancreatic parenchyma appeared normal, the portal vein was encased by pancreatic tissue and the main pancreatic duct (MPD) had a retroportal course (Figure A and Video A). These findings were confirmed in a pancreatic-protocol computed tomography scan, which, after an oblique axial reconstruction, showed a normal, nondilated MPD posterior to the portal vein (Figure B and Video B). The patient was considered to have recurrent idiopathic pancreatitis. The diagnosis of portal annular pancreas with retroportal main pancreatic duct also was made but it was regarded as incidental. Portal annular pancreas is a congenital pancreatic variant in which the uncinate process encases the portal vein, extending to the dorsal surface of the body of the
A
pancreas. Three types of portal annular pancreas have been described: type I in which the MPD is located posterior to the portal vein (as in this case), type II in which type I is associated with pancreas divisum, and type III in which MPD runs anterior to the portal vein.1 Although portal annular pancreas is not associated with an increased risk of pancreaticobiliary disease per se, it may be misdiagnosed as a mass or tumor encasement of the portal vein.2 Its prevalence is thought to be 2.4%, but it has been reported to be an incidental finding during or after pancreatic surgery in half of the reported cases to date, suggesting a low level of awareness or that it may not be recognized readily.3 This could, possibly, explain why the condition was not recognized at magnetic resonance cholangiopancreatography before referral to our institution. However, patients with unrecognized portal annular pancreas undergoing pancreatic surgery for other reasons have been reported to have a risk of 46.7% of postoperative pancreatic fistula.3 The imaging features of portal annular pancreas, in particular those at transaxial tomographic scanning, have been described,4 and we present a case of portal annular pancreas diagnosed by EUS.
References 1.
Joseph P, Raju RS, Vyas FL, et al. Portal annular pancreas. A rare variant and a new classification. JOP 2010;11:453–455.
2.
Leyndecker JR, Baginski SG. Complete pancreatic encasement of the portal vein (circumportal pancreas): imaging findings and
Clinical Gastroenterology and Hepatology 2015;13:e175–e176
ELECTRONIC IMAGE OF THE MONTH, continued implications of a rare pancreatic anomaly. J Comput Assist Tomogr 2008;32:61–64. 3.
Harnoss JM, Harnoss JC, Diener MK, et al. Portal annular pancreas. A systematic review of a clinical challenge. Pancreas 2014;43:981–986.
4.
Gonoi W, Akahane M, Akai H, et al. Retroportal main pancreatic duct with circumportal pancreas: radiographic visualization. Clin Imaging 2011;35:442–446.
e176
Conflicts of interest The authors disclose no conflicts. Most current article © 2015 by the AGA Institute 1542-3565/$36.00 http://dx.doi.org/10.1016/j.cgh.2015.04.026