Paraduodenal pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum and the common bile duct.
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Terminology
The following entities with which it shares clinicopathological features are unified by this term and should no longer be used 11,12:
cystic dystrophy of heterotopic pancreas
pancreatic hamartoma of duodenum
myoadenomatosis
duodenal wall cyst
groove pancreatitis
Epidemiology
The epidemiology of paraduodenal pancreatitis is similar to that of run-of-the-mill chronic pancreatitis.
This rare entity is predominantly seen in males with a history of alcohol abuse. Peak incidence is roughly 40-50 years old 11,12.
Clinical presentation
The clinical presentation of paraduodenal pancreatitis is dominated by symptoms resulting from marked duodenal stenosis and impaired motility with patients presenting with nausea and vomiting.
Symptoms comprise:
recurrent episodes of upper abdominal pain and nausea, typically aggravated by fat or protein-rich meals
weight loss from poor nourishment
Possible signs include:
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slight elevation of serum markers
-
usually unremarkable level of tumor markers, e.g.
Jaundice is a rare finding, despite the frequent involvement of the common bile duct in terms of tubular stenosis.
Pathology
The pathogenesis of paraduodenal pancreatitis remains controversial.
The hallmark of disease is the presence of scar tissue with fibrosis in the pancreaticoduodenal groove or in the groove and the superior portion of the pancreatic head (in the pure and segmental forms of the disease, respectively).
The duodenum is always involved by a chronic inflammatory process, with scar tissue in the wall leading to fibrosis and various levels of stenosis.
Etiology
Paraduodenal pancreatitis has been suggested to occur via increased viscosity of the pancreatic juice caused by alcohol, thus predisposing to crystal formation and increased production of protein, resulting in stone formation. Impeding the minor papilla either pathoanatomically or functionally, this process incapacitates exocrine pancreatic function.
The presence of affected pancreatic elements in the duodenal wall leads to inflammatory injury of the descending (second) part of the duodenum in the pancreatic groove. Changes may be cystic and/or stenotic 11,12.
Microscopic appearance
Histopathological features have been demonstrated to include 11,12:
dilated pancreatic ducts
duodenal wall pseudocysts
granulation tissue containing fused macrophages of foreign-body type
hyperplasia of Brunner glands
heterotopic pancreatic acinar tissue interspersed by dense myofibroblastic and neural proliferation
involvement of the pancreaticoduodenal groove by fibrotic inflammatory changes
Radiographic features
Paraduodenal pancreatitis is usually classified into two forms, pure and segmental:
pure form: exclusively affects the groove
segmental form: extends to the pancreatic head despite a clear predominance in the groove
Ultrasound
Transabdominal ultrasound
May demonstrate 5,11:
thickening of the second part of the duodenum
possible continuity to a hypoechoic mass near the pancreatic head
-
additional findings reflecting the background pathologic processes
mild to moderate dilatation of pancreatic duct and common bile duct dilatation, possibly mimicking the "double duct sign"
Endoscopic ultrasound (EUS)
May be preferred over transabdominal imaging as it more readily demonstrates the expected pathological changes comprising of:
circumscribed hypoechoic change between the duodenal wall and the pancreatic parenchyma
thickening of duodenal wall and associated stenosis
pancreatic calcifications and pseudocysts
stenotic changes of the common bile duct
dilatation of the pancreatic duct
EUS may also allow for guided needle tissue samples 11.
CT
May depict pathological changes accurately. The following findings have been described in the literature:
cystic thickening of the duodenal wall with or without duodenal stenosis
fibrous tissue within the pancreaticoduodenal groove (may show late enhancement after contrast administration)
common bile duct dilatation
MRI
The most characteristic finding on MRI is a sheet-like mass between the head of the pancreas and the duodenum 4.
Signal characteristics include:
T1: hypointense to pancreatic parenchyma
T2: hypo-, iso-, or slightly hyperintense
Associated findings include:
inflammatory changes of the pancreas
local cysts
regular tapering of the pancreatic and common bile ducts
widening of the space between the distal pancreatic and common bile ducts, and duodenal lumen at MRCP 10
banana-shaped gallbladder 10
Treatment and prognosis
Conservative treatment options include analgesics, pancreatic rest and abstinence from alcohol. Symptom relief by these measures is frequently not permanent, as they are unable to stop the underlying background pathologic changes.
Organ-sparing surgery with modified Whipple procedure as either pylorus-preserving pancreaticoduodenectomy or Frey procedure have been demonstrated to result in good and lasting pain relief together with improvement in quality of life 14,15.
History and etymology
It was first described by Volker Becker, a German physician) in 1973 3.
The term “groove pancreatitis” appeared later, coined in 1982 by Stolte et al., members of Becker's research group. It is the direct translation of the original term "Rinnenpankreatitis".
A distinction between "pure groove pancreatitis" and "segmental groove pancreatitis" was also reported by the Becker group 16:
“pure groove pancreatitis”: scarring limited to the groove area and,
“segmental groove pancreatitis,” involvement of the pancreatic head
Differential diagnosis
pancreatic adenocarcinoma of the head of the pancreas is the most relevant differential diagnosis of paraduodenal pancreatitis (particularly in its segmental form). Fine needle aspiration (FNA) tissue samples may present a challenge for the interpreting pathologist.
duodenal adenocarcinoma mainly when they appear as focal thickening of the medial duodenal wall could be hard to differentiate from paraduodenal pancreatitis
acute pancreatitis involving the pancreaticoduodenal groove