Teaching Case

59-year-old female patient was admitted to our department for a follow up after subsegmentectomy due to metastasis of renal cell carcinoma. She was asymptomatic with slightly elevated bilirubin levels.

Contrast-enhanced coronal CT images of the abdomen show outpouching of the second (vertical) segment of the duodenum that is causing compression of the intrapancreatic part of the common bile duct and is resulting in upstream dilatation.

In up to 27% of patients undergoing upper gastrointestinal tract evaluation, duodenal diverticula are discovered. They are most prevalent in the second and third portion of the duodenum [1-3]. They are pseudo-diverticula, outpouchings of mucosa, which lack a muscularis layer. The most common (70-75%) are those located within 2-3 cm of the ampulla of Vater - periampullary diverticula (PAD) [1, 2]. PAD are largely asymptomatic but in 5% they can cause both non-pancreaticobiliary and pancreaticobiliary complications. Non-pancreaticobiliary complications are rare and may include diverticulitis, perforation, haemorrhage or fistula formation. Pancreaticobiliary complications can present as recurrent gallstones, obstructive jaundice, cholangitis, or acute pancreatitis. Obstructive jaundice secondary to PAD in the absence of choledocholithiasis or tumour is termed Lemmel syndrome [1-5].
There are three pathways of pathogenesis that lead to the development of Lemmel syndrome. First, direct mechanical irritation of PAD may cause chronic inflammation of the ampulla and this subsequently leads to fibrosis of the papilla. Second, PAD may cause dysfunction of the sphincter of Oddi. Third, the distal common bile duct or ampulla can be compressed mechanically by PAD as it also happened in our patient [1, 2].
As diagnosing Lemmel syndrome is often a difficult task, it should always be considered in patients with PAD. On CT, PADs appear as thin-walled cavitary lesions, originating from the medial aspect of the 2nd portion of the duodenum that typically contain gas. There can be either solid or cystic lesion which can often be mistaken for a pancreatic pseudocyst, abscess, or cystic neoplasm. MRCP can be used to distinguish diverticulum from pseudocysts or cystic tumors of the pancreatic head. However, a side-viewing endoscope during ERCP is considered to be the gold standard diagnostic method [1, 2, 4]
In asymptomatic patients treatment is not universally recommended while for symptomatic patients diverticulectomy remains the treatment of choice [2, 4].