Incomplete annular pancreas: Pancreatic tissue may extend anterolateral or posterolateral to duodenum or anterior and posterior to duodenum (“crocodile-jaw” configuration)
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MR: Normal pancreatic tissue (with identical signal to normal pancreas) encircling duodenum
MRCP: Main pancreatic duct encircling duodenum (and abnormally extending to right side of duodenum)
Secretin dilates duct and facilitates diagnosis
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Fluoroscopic barium study (upper GI): Extrinsic smooth compression and narrowing of 2nd part of duodenum
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ERCP: Duct draining pancreatic head encircles the duodenum and joins normal main pancreatic duct
TOP DIFFERENTIAL DIAGNOSES
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Pancreatic ductal carcinoma
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Postbulbar peptic ulcer
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Multiple other causes of duodenal stenosis
PATHOLOGY
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Etiology: Incomplete rotation of ventral anlage leads to pancreatic tissue encircling 2nd part of duodenum
Other congenital anomalies in up to 75% of pediatric cases (Down syndrome, duodenal atresia, etc.)
CLINICAL ISSUES
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50% of cases present in infancy due to gastric outlet obstruction
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Most adults asymptomatic, but rare symptoms include gastric obstruction, upper GI bleeding, and jaundice
Rare symptoms include partial gastric outlet obstruction, upper GI bleeding, abdominal pain, and obstructive jaundice
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Associated in adults with gastric/duodenal ulcers and pancreatitis; questionable link with pancreatic cancer
Related
Diagnostic Imaging_ Gastrointes - Michael P Federle
