Groove pancreatitis is an unusual cause of chronic abdominal pain. It is not a disease of the pancreas proper. Cystic degeneration of hamartomatous pancreas rests within the medial duodenal wall lead to the development of fibrotic and inflammatory tissue within the pancreaticoduodenal groove. Typical radiological features have been well described. (1) However, little information has been published on atypical and end-stage imaging characteristics. These atypical cases often have impressive and bizarre imaging features that can overlap with findings of cancer. The breadth of imaging findings varies widely. Introduction The mean age is 50 and there is a significant male predominance. Chronic relapsing upper abdominal pain and weight loss are common. Chronic alcoholism is the only well-established risk factor. Clinical Presentation Therapies range from conservative medical therapy to endoscopic stenting, laparotomy with a Whipple procedure. (2-5) Treatment Histopathology + Pathophysiology Characterized by chronic inflammation and scarring in the pancreatico- duodenal “groove”. Hamartomatous rests of pancreas within the medial duodenal wall undergo cystic degeneration from chronic stress, which are presumed to be related to alcohol induced ischemia. (1) Two established typical gross morphologic forms exist: pure and segmental. In the pure form abnormalities are confined to the groove. In the segmental form the inflammation and scarring extend from the groove to involve the head of the pancreas proper. (1) 1. Raman SP, Salaria SN, Hruban RH, Fishman EK. Groove pancreatitis: spectrum of imaging findings and radiology-pathology correlation. AJR Am J Roentgenol 2013; 201:W29-W Levenick JM, Sutton JE, Smith KD, Gordon SR, Suriawinata A, Gardner TB. Pancreaticoduodenectomy for the treatment of groove pancreatitis. Dig Dis Sci 2012; 57: Casetti L, Bassi C, Salvia R, et al. "Paraduodenal" pancreatitis: results of surgery on 58 consecutives patients from a single institution. World J Surg 2009; 33: Isayama H, Kawabe T, Komatsu Y, et al. Successful treatment for groove pancreatitis by endoscopic drainage via the minor papilla. Gastrointest Endosc 2005; 61: Egorov VI, Butkevich AC, Sazhin AV, Yashina NI, Bogdanov SN. Pancreas-preserving duodenal resections with bile and pancreatic duct replantation for duodenal dystrophy. Two case reports. JOP 2010; 11: Hungerford J, Magarik M, Hardie A Medical University of South Carolina B READTH OF D ISEASE F INDINGS WITH G ROOVE P ANCREATITIS References Figure 1. Typical Groove Pancreatitis with a non-enhancing fibrotic mass in the “groove” (red arrow) and duodenal cystic degeneration and wall thickening (curved green arrow). “Pure” form with duodenal thickening and a sheet-like mass in the groove but no involvement of the pancreas (yellow arrow). “Segmental” form with a cystic pancreatic head mass (blue arrow) and wall cystic change (not shown). Figure 2. Spectrum of duodenal wall cystic degeneration of the pancreatic hamartomas. Medial wall thickening (blue box) and small cysts ( yellow arrow) are typical. However the duodenal wall cysts can vary in size, and in some cases can be quite large (blue arrow) and complex (red arrow). Figure 6. Pancreatic ductal dilation and calcifications due to long-standing obstruction from a cystic mass in the groove (yellow star). Figure 3. Spectrum of biliary and pancreatic ductal dilation. CBD and PD abnormalities are seen often in the “segmental form”. Ductal dilation in the “pure form” is occasionally seen and is caused by extrinsic pancreatic head compression from groove cysts or masses. Dilation can become severe with worsening extrinsic compression. Figure 4. Large solid, non- enhancing masses in the groove and the pancreatic head. Figure 5. A large part-solid (green) and part-cystic (yellow) non-enhancing mass within the groove. Morphology of the fibrotic mass can vary greatly. ★