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48uep6bbph|2000F98CTab_Articles|Fulltext

Gastric outlet obstruction in the setting of chronic pancreatitis raises the possibility of pancreatic malignancy. Intramural pseudocysts are a rare cause of gastric outlet obstruction and are challenging to diagnose by conventional imaging. We describe two cases of gastric outlet obstruction in the setting of chronic pancreatitis, finally diagnosed as intramural pseudocysts by endoscopic ultrasound.

A 55-year old male with chronic calcific pancreatitis presented with a history of persistent vomiting and weight loss. A gastroduodenoscopy revealed duodenal narrowing and significant food residue in gastric lumen suggestive of gastric outlet obstruction. An ultrasound of the abdomen suggested a mass-like lesion in the head of the pancreas inseparable from the duodenal wall. A provisional diagnosis of pancreatic malignancy causing gastric outlet obstruction was made. The patient underwent endoscopic ultrasound (EUS) and fine-needle aspiration (FNA) from the mass lesion. The EUS image (Figure 1) showed several cystic lesions within the duodenal wall suggestive of intramural pseudocysts causing luminal narrowing. The pancreatic calcifications were also visible. The aspiration of larger cysts provided symptomatic relief to the patient. The patient improved with conservative management.

The second patient was a 40-year old male with chronic calcific pancreatitis who presented with recurrent vomiting and weight loss for one month. An ultrasound of the abdomen suggested the presence of a mass-like lesion in the head of the pancreas. A provisional diagnosis of pancreatic malignancy causing duodenal compression and gastric outlet compression was made. The patient was taken up for endoscopic ultrasound (EUS) guided fine needle aspiration (FNA) from the mass lesion. The EUS image (Figure 2) showed marked duodenal wall thickening in relation to head of the pancreas, multiple calcifications within the pancreas with acoustic shadowing, and an intramural pseudocyst in the duodenal wall. Thus, a diagnosis of groove pancreatitis (and not pancreatic malignancy) was made. A nasojejunal tube was placed for feeding. The patient improved with conservative management.

The most frequent cause of gastric outlet obstruction in the setting of chronic pancreatitis is pancreatic malignancy. Intramural pseudocysts are generally small and difficult to pick up by conventional imaging. Intramural pseudocysts of the duodenum are rare and luminal obstruction is very rare.¹ The second part of duodenum is commonly involved; the first and third parts may also be affected.² The first patient had gastric outlet obstruction due to the presence of several intramural cysts, which is unique in this case. Due to high resolution and proximity to the target lesion, EUS is very helpful in such cases by providing an accurate diagnosis and avoids extensive evaluation.³ Differentiating pancreatic cancer from an inflammatory mass lesion is difficult in presence of chronic calcific pancreatitis with dense calcifications, and even EUS guided FNA has low diagnostic accuracy in the presence of chronic pancreatitis. The second case was diagnosed as groove pancreatitis. Groove pancreatitis is a form of chronic focal pancreatitis that affects the area between duodenum, bile duct, and head of the pancreas. Patients may present with pain, bile duct obstruction, or gastric outlet obstruction. The histopathological analysis shows the presence of scar tissue with fibrosis.⁴ Although groove pancreatitis mimics malignancy,  cystic duodenal thickening is highly suggestive of benign pathology (groove pancreatitis).^5,6