Clinicoradiological appraisal of 'paraduodenal pancreatitis': Pancreatitis outside the pancreas!

Abstract

Purpose: Paraduodenal pancreatitis (PP) is a unique form of focal chronic pancreatitis that selectively involves the duodenum and aberrant pancreatic tissue located near the minor papilla (beyond the pancreas proper). The pseudotumoral nature of the disease often generates considerable clinical quandary and patient apprehension, and therefore merits a better understanding. The present study appraises the clinicoradiological manifestations of PP in 33 patients.

Materials and methods: Clinical, laboratory, and radiological manifestations of 33 patients of PP treated in gastroenterology/hepatology and hepato-pancreatico-biliary surgery units during June 2010-August 2014 were retrospectively reviewed.

Results: All patients were young to middle-aged men (100%) with history of alcohol abuse (93.9%) and/or smoking (42.4%), who presented either with acute or gradually worsening abdominal pain (90.9%). Pancreatic enzymes and serum tumor markers remained normal or were mildly/transiently elevated. Cystic variant was detected in 57.6% (solid in 42.4%); the disease remained confined to the groove/duodenum (pure form) in 45.4%. Medial duodenal wall thickening with increased enhancement was seen in 87.87 and 81.81%, respectively, and duodenal/paraduodenal cysts were seen in 78.78%. Pancreatic calcifications and biliary stricture were seen 27.3% patients. Peripancreatic arteries were neither infiltrated nor encased.

Conclusion: PP has a discrete predilection for middle-aged men with history of longstanding alcohol abuse and/or smoking. Distinguishing imaging findings include thickening of the pancreatic side of duodenum exhibiting increased enhancement with intramural/paraduodenal cysts. This may be accompanied by plate-like scar tissue in the groove region, which may simulate groove pancreatic carcinoma. However, as opposed to carcinoma, the peripancreatic arteries are neither infiltrated nor encased, rather are medially displaced.

Keywords: Chronic pancreatitis; computed tomography; magnetic resonance imaging; pancreatitis.

Figure 1

Pictorial illustration of paraduodenal pancreatitis depicting a fibroinflammatory mass (PP) in the pancreatico-duodenal groove (PDG) with concurrent duodenal and paraduodenal cysts (C) in the region of minor papilla (MP). P: Pancreas; DS: Duct of Santorini; DW: Duct of Wirsung

Figure 2

Etiopathogenesis of paraduodenal pancreatitis

Figure 3

Schematic illustration of the pathological manifestations of paraduodenal pancreatitis

Figure 4

Axial contrast-enhanced CT displaying medial duodenal wall thickening with mural hyperenhancement (arrow). In addition, paraduodenal cyst is noted (arrowhead) along with a hypoenhancing soft tissue (dotted arrow) sandwiched between the pancreatic head and the descending duodenum

Figure 5(A-D)

(A and B) Cystic variant of paraduodenal pancreatitis displaying extensive cystic formations in the groove (thick arrow) causing medial displacement of the gastroduodenal artery which otherwise is normal in caliber (thin arrow) (C and D) Solid variant of paraduodenal pancreatitis wherein a hypoattenuating sheet-like fibrous tissue is seen within the pancreatico-duodenal groove (arrow)

Figure 6(A and B)

(A) “Pure” form of disease characterized by a normal-appearing pancreatic head (thick arrow) and the inflammatory changes remaining confined to the groove region (thin arrow) (B) “Segmental” form of disease wherein the head of the pancreas is concurrently involved and shows a hypoenhancing lesion (thick arrow). Predominantly cystic form of the disease can be seen within the groove (thin arrow)

Figure 7(A and B)

(A) A 50-year-old patient with paraduodenal cystic lesions (arrowheads) displaying calcifications localized to the pancreatic head (arrow). Also, note the changes of alcohol-related liver disease (dotted arrows) and ascites (asterisk) (B) A 52-year-old patient with paraduodenal pancreatitis and a large paraduodenal cyst (arrowhead) showing an atrophic pancreas with diffuse calcifications (arrows)

Figure 8

Thick slab 2D MRCP in a 33-year-old patient of paraduodenal pancreatitis showing excessive widening of the space between the descending duodenum (D) and the bile duct (thin arrow). An ectatic and elongated banana-shaped gallbladder can also be seen (thick arrow)

Figure 9(A and B)

Transabdominal ultrasonography (A) depicting thickened (arrows) descending duodenal wall (D2) accompanying a relatively bulky heteroechoic (arrowheads) head of pancreas (HOP) in an alcoholic patient with paraduodenal pancreatitis (B) A different patient of paraduodenal pancreatitis with duodenal thickening (D2) and accompanying cystic formation (arrowhead)

Figure 10(A and B)

Unenhanced MRI of abdomen in a 48-year-old chronic alcoholic male showing a mass (arrow) in the groove region sandwiched between the pancreatic head (arrowhead) and descending duodenum (dotted arrow). The mass depicts hypointense signal on T1W (A) and isointense signal on the corresponding T2-weighted image (B)

Figure 11(A and B)

(A and B) Thick slab 2D MRCP depicting characteristic features of paraduodenal pancreatitis as evidenced by paraduodenal cystic formations (thick arrow) with associated widening of the space between the descending duodenum, bile duct, and the pancreatic duct. There is associated smooth tapering of the distal bile duct (thin arrow). The pancreatic duct in the head region shows smooth decrease in diameter (arrowhead) with modest dilatation of the upstream duct (dotted arrow)

Figure 12(A and B)

EUS showing medial duodenal wall thickening (A) with accompanying intraparietal cysts (thin arrow) within the duodenum (B) Also, note focal pancreatic calcification (thick arrow) (A)