Autoimmune pancreatitis (AIP) is a chronic inflammation which is believed to be a consequence of the body's immune system attacking the pancreas and responding to steroid therapy. Today we distinguish two subtypes of AIP, type 1 and type 2. It is treated with steroids, which in many people dramatically improve the condition.

  • Type 1 AIP (G4-related pancreatitis) is part of a disease called IgG4-related disease (IgG4-RD) that often affects multiple organs including the pancreas, bile ducts in the liver, salivary glands, kidneys and lymph nodes.
  • Type 2 AIP affects only the pancreas, although about one-third of people with type 2 AIP have associated inflammatory bowel disease.

Autoimmune pancreatitis is a rare, newly recognized disease and can be mistakenly diagnosed as pancreatic cancer because both conditions have similar symptoms, but very different treatments, so it is very important to distinguish them clearly.

Symptoms

Autoimmune pancreatitis (AIP) is difficult to diagnose. Often, it does not show any symptoms, but when it does, the symptoms are very similar to those of pancreatic cancer.

Pancreatic cancer symptoms can be:

  • Loss of appetite or feelings of fullness,
  • Dark urine,
  • Pale stools or stools that float in the toilet,
  • Yellow skin and eyes (jaundice),
  • Pain in your upper abdomen or middle part of your back,
  • Nausea and vomiting,
  • Weakness or extreme tiredness,
  • Weight loss for no known reason,

Mainly type 1 autoimmune pancreatitis occurs in people who:

  • Are over age 60
  • Are male
  • Have several organs involved including the bile ducts (IgG4-related sclerosing cholangitis), the salivary glands (IgG-related sialadenitis), or the lungs (IgG4-related pulmonary disease)
  • Have retroperitoneal fibrosis (RPF), which is the formation of extra fibrous tissue in the area behind the stomach and intestine
  • Have lymph node enlargement (lymphadenopathy), low thyroid (hypothyroidism) or kidney disease

People with type 2 autoimmune pancreatitis:

  • Are often over age 40
  • Are both men and women
  • Have a 30 percent chance of having inflammatory bowel disease, such as ulcerative colitis

Causes

What causes autoimmune pancreatitis is unknown, but as in other autoimmune diseases, the body's immune system attacks healthy body tissue.

Risk Factors

Risk of autoimmune pancreatitis, like in pancreatic cancer include people of/with:

  • African-American race
  • Excess body weight
  • Chronic inflammation of the pancreas (pancreatitis)
  • Diabetes
  • Family history of genetic syndromes that can increase cancer risk,
  • Personal or family history of pancreatic cancer
  • Smoking

Complications

Autoimmune pancreatitis can cause a variety of complications.

  • Pancreatic insufficiency.
  • Diabetes.
  • Pancreatic calcifications or stones.

There is no established association between AIP and pancreatic cancer.