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Findings in this case: Pancreatic parenchyma is demonstrated surrounding the duodenum. There is no evidence of pancreatitis.
Diagnosis: Annular Pancreas.
File:4 C.
Organ system: 4.0 Hepatobiliary Tract.
Organ :C. Pancreas.
Etiology and incidence: 1) The overall incidence is estimated at 1 in 20,000 autopsies and up to 1 in 15,000 live births. In 1 series reviewing the ERCP findings, it was noted that there was one case in 250 patients. Annular pancreas as a cause of extrahepatic biliary obstruction.Baggott BB, Long WB,Am J Gastroenterol. 1991; 86(2):224. http://www.uptodate.com/contents/annular-pancreas/abstract/3; a) True incidence is unclear though clearly this is a rare abnormality. 2) This has been reported to be more common in males in females. 3) Annular pancreas is fully associated with other congenital abnormalities including duodenal atresia or stenosis, a malrotation, Down’s syndrome (Reported in up to 30% of Down’s patient’s) and esophageal atresias. 4) The etiology is most frequently attributed to one of 2 causes; a) The ventral pancreatic bud forms a bifid growth around the duodenum; b) The ventral pancreatic bud fails to rotate.
Diagnosis: 1) CT and MRI; a) Continuous pancreatic parenchyma which encircles or partially encircles the duodenum; b) Not able to be demonstrated with certainty on ultrasound after birth; c) On MRCP (or ERCP) there will be a duct encircling the duodenum. 2) Fluoroscopic and plain film studies; a) “Double bubble” sign typically in neonates; b) Can see concentric narrowing of the descending portion of the duodenum. 3) OB ultrasound; a) Can be associated with the “double bubble” sign of dilatation of the stomach and proximal duodenum. In these cases, the differential also includes duodenal webs, duodenal atresia and stenosis and midgut volvulus/malrotation. 4) Differential diagnosis; a) Pancreatic neoplasm; b) Duodenal neoplasm; c) Duodenitis; d) Duplication cysts of the duodenum and/or duodenal atresias.
Prognosis/Clinical: 1) Annular pancreas is asymptomatic in and of itself however given its association with other congenital abnormalities diagnosis is more commonly due to exploration of these abnormalities. 2) Pancreatitis with associated inflammation of the duodenum and/or stenosis of the duodenum can occur and is also a cause for evaluation by CT leading to the diagnosis. 3) Depending upon the associated congenital or acquired anomalies, presentation can be in infancy or in adulthood. 4) Treatment; a) No treatment if asymptomatic. Clinical follow-up is necessary to prevent complications of progressive duodenal stenosis associated with gastric and duodenal ulcers and pancreatitis; b) If symptomatic, surgical bypass is required.
References:
Congenital Anomalies and Normal Variants of the Pancreaticobiliary Tract and the Pancreas in Adults: Part 1, Pancreatic Duct and Pancreas.
http://www.ajronline.org/cgi/reprint/187/6/1536.pdf
Congenital Anomalies and Normal Variants of the Pancreaticobiliary Tract and the Pancreas in Adults: Part 2, Pancreatic Duct and Pancreas.
http://www.ajronline.org/cgi/reprint/187/6/1544.pdf
Annular Pancreas
Charles E. Lohr, III, MD; Todd Emch, MD; Harry Patton, DO; Margaret A. Miller, MD
http://www.medscape.com/viewarticle/556156
R J Rizzo, R A Szucs, and M A Turner
Congenital abnormalities of the pancreas and biliary tree in adults. Radiographics January 1995 15:49-68
…adults (28). Adults with annular pancreas usually do not have other as-sociated…28). The symp-toms and signs of annular pancreas in the adult are usually nonspecific…et al #{149}RadioGraphics I 65. ANNULAR PANCREAS Annular pancreas is a rare congenital…
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Nam Kyung Lee, Suk Kim, Tae Yong Jeon, Hyun Sung Kim, Dae Hwan Kim, Hyung Il Seo, Do Youn Park, and Ho Jin Jang
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