Periampullary duodenal diverticulum causing obstruction of CBD

Clinical History

A 50-year-old female patient came with right hypochondrium pain. USG showed dilated common bile duct and pancreatic duct with intrahepatic biliary radicles dilatation (IHBRD). Patient came for MRCP to rule out ampullary / periampullary pathology.

Imaging Findings

MRCP showed dilatation of CBD, measuring up to 11.0 mm. A curvilinear extrinsic smooth indentation on the inner wall of the CBD near the ampulla was seen. Bilobar moderate IHBRD was also noted. The pancreatic duct was normal. No cholelithiasis / choledocholithiasis was seen. CT of the upper abdomen was done after giving oral contrast to see the duodenum and ampulla. CT revealed a focal outpouching approximately measuring 8.0 x 8.0 x 12.0 mm arising from the medial wall of the 2nd part of duodenum near the ampulla causing compression on the distal CBD resulting in dilatation of CBD and IHBR. The oral contrast was seen in the focal outpouching with air pocket suggestive of communication with the duodenal lumen. Hence it was confirmed that the indentation on the distal CBD seen on MRCP was due to periampullary duodenal diverticulum causing distal CBD obstruction.

Discussion

Periampullary duodenal diverticula are not uncommon and are usually asymptomatic although complications may occasionally occur. Duodenal diverticula are mostly true or primary diverticula representing extraluminal mucosal outpouchings devoid of muscle layer. In 90% of cases they are solitary and approximately 75% of them are located in the second part of the duodenum, mostly in its concave medial aspect adjacent to the ampulla of Vater. When they arise within 2–3 cm from the ampulla of Vater they are named periampullary, peripapillary or paravaterian diverticula. Periampullary diverticula are not rare. Their prevalence varies from 0.16 to 22% depending on the diagnostic method used (barium meal, endoscopic retrograde cholangiopancreatography or autopsy) and increases with age. The majority of periampullary diverticula are asymptomatic and are found incidentally during endoscopic or imaging procedures, but occasionally non-pancreaticobiliary or pancreaticobiliary complications may occur. Obstructive jaundice in the absence of gallstones due to a periampullary duodenal diverticulum is also known as Lemmel's syndrome and may be recurrent or complicated by cholangitis and is attributed to mechanical external compression of the terminal bile duct by the diverticulum [1].
Imaging Findings: On barium studies, periampullary diverticula are typically demonstrated as contrast-filled outpouchings arising from the medial side of the descending duodenum. Filling defects, if present, commonly represent food fragments, retained air or the protruding into the diverticulum ampulla, as in this case. On computed tomography images periampullary diverticula are characterized by the presence of air-contrast level within a juxtaduodenal outpouching. On magnetic resonance imaging, the T2-weighted images show a hyperintense fluid level with signal void above it due to the presence of air. Half-Fourier Acquisition Single-Shot Turbo Spin-Echo (HASTE) images and true Fast Imaging with Steady Precession (FISP) images demonstrate the diverticular wall as well as its relation to the papilla. MRCP is the method of choice when assessing the consequences of a diagnosed diverticulum on the CBD and to differentiate the diverticulum from pseudocysts or cystic tumours of the pancreatic head [1].
Treatment: In cases of biliary obstruction, excision of the diverticulum (diverticulectomy) is an appropriate procedure, but it can be difficult and is associated with a significant mortality and morbidity [2]. Bypass procedures such as choledochoduodenostomy, Roux-en-Y choledochojejunostomy and procedures such as duodenal diverticulization and duodenojejunostomy aiming at duodenal decompression and inversion or reconstruction of the diverticular sac through a duodenotomy may also be useful [3].

Differential Diagnosis List

Final Diagnosis

Periampullary duodenal diverticulum causing obstruction of CBD.

URL:	https://www.eurorad.org/case/11246
DOI:	10.1594/EURORAD/CASE.11246
ISSN:	1563-4086