What is Autoimmune Pancreatitis?

Diagnosis and Treatment Autoimmune pancreatitis is a rare form of chronic pancreatitis that develops due to the reaction of the immune system against the pancreatic tissue. It may occur as a primary pancreatic disease, or may progress with other autoimmune diseases (eg primary sclerosing cholangitis, primary biliary cirrhosis, retroperitoneal fibrosis, rheumatoid arthritis, sarcoidosis, Sjögren’s syndrome). It is also called autoimmune pancreatitis, sclerosing pancreatitis, nonalcoholic destructive pancreatitis  Although glucocorticoids are used in the treatment (recommended dose: starting prednisone at a dose of 40 mg/day and stopping the treatment after 4-6 weeks by 5 mg per week), the optimal dose and duration are still unknown.

Autoimmune pancreatitis is a form of chronic pancreatitis with distinctive clinical, histological and morphological features. This form of chronic pancreatitis was first described by Sarles et al. in 1961, and the term autoimmune pancreatitis was first used by Yoshida et al. in 1995. In 2003, Kamisawa et al. mentioned that autoimmune pancreatitis is a systemic disease, and the presence of IgG4 positive staining plasma cells in the pancreas and other affected organs. autoimmune pancreatitis; It may occur as a primary pancreatic disease or may progress with other autoimmune diseases (eg primary sclerosing cholangitis, primary biliary cirrhosis, retroperitoneal fibrosis, rheumatoid arthritis, sarcoidosis, Sjögren’s syndrome).

Autoimmune pancreatitis can also be seen as a focal lesion mimicking pancreatic carcinoma. Although this condition is most commonly seen in the head of the pancreas, it can also be located in the trunk and tail, or it can be found in the form of more than one lesion.

Terminology? It is also called autoimmune pancreatitis, sclerosing pancreatitis, nonalcoholic destructive pancreatitis. Detection of IgG4 positive staining plasma cells in the pancreas or other affected tissues is an important finding supporting autoimmune pancreatitis. It has been emphasized in the literature that IgG4-related cholangitis is not a separate clinical picture, but a biliary manifestation of autoimmune pancreatitis.

Clinical Findings

  • Moderate abdominal pain without pancreatitis attack,
  • Obstructive jaundice,
  • Diffuse swelling and enlargement especially evident in the pancreatic head on imaging, mimicking pancreatic carcinoma in the late stage
  • Diffuse irregularity in the pancreatic duct, • Increase in serum gammaglobulin level, especially increase in IgG4 level,
  • Other autoantibody [such as antinuclear antibody (ANA), rheumatoid factor (RF)] positivity,
  • Cyst or calcification in the pancreas is not often accompanied, • Association with other autoimmune diseases (such as Sjögren’s, sclerosing cholangitis, ulcerative colitis, rheumatoid arthritis),
  • Stenosis in the main bile duct and intrahepatic bile ducts,
  • Presence of advanced fibrosis and lymphoplasmocytic infiltration in pancreatic biopsies,
  • Reduction in pancreatic size and improvement in histological changes with corticosteroid therapy. Extrapancreatic Findings
  • Inflammatory bowel disease (often ulcerative colitis),
  • Autoimmune sclerosing cholangitis,
  • Nodules, adenopathy and infiltrations in the lung,
  • Sjogren’s syndrome,
  • Retroperitoneal fibrosis,
  • Often long segment structures in the bile ducts,
  • Tubulointerstitial nephritis,
  • Autoimmune thyroiditis.

Clinical Profile

There are two different histological types of autoimmune pancreatitis and the clinical findings of these two different histological types are also different. Type 1 Autoimmune Pancreatitis is also called Lymphoplasmocytic sclerosing pancreatitis. Diagnosed by microscopic examination at high magnification, by the presence of more than 10 IgG4-positive staining cells and at least two of the following:

  • Periductal lymphoplasmocytic infiltration,
  • Obliterative phlebitis,
  • Acinar fibrosis.

Type 2 Autoimmune Pancreatitis It is called idiopathic duct centric pancreatitis. Neutrophilic infiltration in the pancreatic duct and detection of IgG4 positive stained cells in the pancreatic parenchyma are supportive findings.

  • Patients with type 1 autoimmune pancreatitis are often older and have higher IgG4 levels than type 2 autoimmune pancreatitis, with more relapses in this group. Extrapancreatic autoimmune diseases are more common in type 1 autoimmune pancreatitis.

Diagnosing Autoimmune Pancreatitis

  • The most important point in the differential diagnosis is the distinction between autoimmune pancreatitis and pancreatic cancer.
  • Pancreatic biopsy is a necessary method for diagnosis, and detection of IgG4 positive plasma cell infiltration in the pancreas and other affected organs are supportive findings in the diagnosis. Autoimmune Pancreatitis Treatment