IS Case 152: Annular pancreas
Imaging Sciences URMC 2008
Publication Date: 2009-05-21
Patient is a 51-year-old male with abdominal pain and diarrhea.
Incidental findings consistent with annular pancreas
The pancreas develops from dorsal and ventral buds originating as envaginations of the primitive foregut at week five of gestation. At the seventh week the ventral bud rotates with the gut, going behind the duodenum, to fuse with the dorsal bud. The ventral bud forms the inferior head and uncinate process while the tail and body originate from the dorsal bud. Annular pancreas results from failure of the ventral bud to rotate with the duodenum causing envelopment of the duodenum with pancreatic tissue. The resulting band completely encircles the second portion of the duodenum.
Annular pancreas may result in narrowing of the duodenum and subsequently obstruction. One in 12,000-15,000 newborns present with this problem. The true incidence of annular pancreas is not known as many cases are asymptomatic and go undetected. Occasionally adults may present with obstruction.
Radiographic tests include an upper GI to see annular constriction at the level of the duodenum or direct visualization with ultrasound or CT.
If the patent is symptomatic then surgical bypass of the blocked duodenum can be performed with a duodeno-doudenostomy or gastrojejunostomy. Prognosis is good and rarely perforation, peritonitis, pancreatitis, or obstructive jaundice can occur.
- Weissleder R, Wittenberg J, Harisinghani MG, Chen JW, et al. Primer of Diagnostic Imaging. 4th ed. Philadelphia, PA: Mosby, 2006.
- Zyromski NJ, Sandoval JA, Pitt HA, et al. Annular pancreas: dramatic differences between children and adults. J Am Coll Surg. 2008 May;206(5):1019-25; discussion 1025-7. [PMID: 18471747]