Autoimmune Pancreatitis

 Often associated with elevated serum IgG4

image Similar fibroinflammatory process often affects other organs such as bile ducts, salivary glands, retroperitoneum, and lymph nodes

• Associated with many other autoimmune diseases; ANA often positive

Clinical Issues

• Nonspecific: Jaundice, weight loss, vague abdominal pain
• Elevated serum IgG4 (not invariably present, and not diagnostic of autoimmune pancreatitis)

image More common in type 1 than type 2 AIP

• Steroid therapy is usually very effective
image Recurrence reported in 6-26%

• Often mimics pancreatic adenocarcinoma clinically and radiographically


• Enlarged, firm pancreas ± mass lesion; may mimic adenocarcinoma
image Usually head is most prominently involved

• Stenosis of pancreatic duct and intrapancreatic common bile duct are common


• Dense, lymphoplasmacytic infiltration centered around main and interlobular pancreatic ducts
• Periductal, lobular, and perilobular fibrosis

• Obliterative phlebitis and venulitis

• 2 main types

image Type 1: Lobular and interlobular distribution, obliterative phlebitis, numerous IgG4(+) plasma cells

image Type 2: Duct-centric distribution, granulocytic epithelial lesions, only rare IgG(+) plasma cells

Surgical Specimen
This pancreatic resection from a case of type 1 autoimmune pancreatitis (AIP) shows a dense, infiltrative, fibrotic process in the head of the pancreas.

Periductal Inflammation, Type 1 Autoimmune Pancreatitis
Low-power view of type 1 AIP shows marked chronic inflammation surrounding a large duct and involving the periductal stroma image .

Phlebitis, Type 1 Autoimmune Pancreatitis
This vein image has been infiltrated by inflammatory cells, with resultant edema and destruction of the wall of the vessel. Note the surrounding fibrosis.

IgG4 Immunostain, Type 1
IgG4 stain in type 1 AIP shows a large number of IgG4(+) plasma cells (> 10/HPF) in the periductal stroma.



• Autoimmune pancreatitis (AIP)


• Lymphoplasmacytic sclerosing pancreatitis (LPSP)

• Idiopathic duct-centric chronic pancreatitis (IDCP)

• Primary sclerosing pancreatitis

• IgG4-related pancreatitis (type 1 only)


• Fibroinflammatory disease of presumed autoimmune etiology 
image Other organs can also be affected

• Associated with many other autoimmune diseases

• Specific antigenic trigger unknown



• Nonspecific: Jaundice, weight loss, abdominal pain, fatigue

Laboratory Tests

• Elevated serum IgG4 (not invariably present, and not diagnostic of autoimmune pancreatitis)
image More common in type 1 than type 2 AIP

• Elevated pancreatic enzymes

• ANA often positive

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Apr 20, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Autoimmune Pancreatitis

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