Groove Pancreatitis: A Diagnostic Quandary

 

Groove pancreatitis is a distinct form of focal chronic pancreatitis, which is uncommon, focused in the groove between the head of the pancreas, the duodenum, and the common bile duct. The clinical presentation is similar to pancreatitis but often with more recurrent vomiting and intermittent jaundice if present, often in 40 to 50-year old men with history of alcoholism. The pathogenesis is often controversial. Some relate it to the past diseases of biliary system, gastric resections, pancreatic heterotopias in the duodenum, duodenal and peptic ulcerations. Histologically, groove pancreatitis is of two types, segmental and pure. The segmental extends into the pancreatic head while pure involves mainly the pancreaticoduodenal groove. Imaging findings are important in making the correct diagnosis and subsequently managing treatment options. Ultrasound demonstrates duodenal wall thickening, with or without surrounding inflammation which shows hypoechoic mass lesion. Contrast enhanced CT shows duodenal changes and enhancing scar tissue in the groove between the C-loop and the pancreatic head. The characteristic feature on MRI is a sheet like mass between the head of pancreas and the C-loop of duodenum. The mass is hypointense to pancreatic parenchyma on T1-weighted sequence and can be hypo-, iso-, or slightly hyperintense on T2-weighted images. After administration of Gd-DTPA, the mass shows delayed enhancement characteristic of fibrous component. The distinction between groove pancreatitis and pancreatic head adenocarcinoma is often difficult on imaging. ERCP and EUS helps in differentiating two identities. There is regular and smooth stenosis of the common bile duct in groove pancreatitis while irregular stenoses with obstructive symptoms are common in malignancy. The malignant mass is more round and discrete than groove pancreatitis. Groove pancreatitis is treated conservately, however surgery is required if there is deterioration of symptoms.