What is Autoimmune Pancreatitis?

Sometimes the body’s immune system mistakenly attacks the pancreas, causing the organ to swell. This is known as autoimmune pancreatitis.

A rare disease, autoimmune pancreatitis is commonly confused with pancreatic cancer, as it often presents as a painless lump or mass on the pancreas. However, treatments for these diseases are very different. That’s why it is important to ensure an accurate diagnosis.

At UChicago Medicine, our experienced pancreatic disease team specializes in identifying and treating rare as well as common pancreatic diseases. Diagnosing autoimmune pancreatitis requires high-quality imaging and, in many cases, a biopsy. For that, our highly-skilled interventional gastroenterologists thread a thin tube (endoscope) through the mouth to the pancreas to take a sample of pancreatic tissue. Then our pathologists examine this tissue under a microscope. Modern laboratory approaches, including some special stains, are used to make it easier to see the hallmark cellular features of autoimmune pancreatitis.

Treatment for Autoimmune Pancreatitis

Autoimmune pancreatitis is typically treated with steroids and/or other drugs that weaken the body’s immune response (known as immunosuppressants or immunomodulators). The exact drug regimen needs to be customized to the patient, taking into account individual factors. For instance, some patients cannot be treated with steroids due to difficulty controlling blood sugar.

Autoimmune pancreatitis responds well to prescription medicine. But a significant number of patients experience repeat attacks of the disease. Reducing recurrences is important because uncontrolled autoimmune pancreatitis can lead to chronic pancreatitis and irreversible damage to pancreatic tissue.

The risk of recurrence depends, in part, on the type of autoimmune pancreatitis a patient has. There are two types:

  • Type 1 (IgG4-related) autoimmune pancreatitis tends to recur in more than 50 percent of patients. In addition to affecting the pancreas, type 1 autoimmune pancreatitis can inflame a patient’s liver, kidneys, thyroid, and other organs. Type 1 typically occurs in older people in their 60s and 70s, and is three times more common in men than women. Type 2 (idiopathic duct-centric) autoimmune pancreatitis only affects the pancreas. After being controlled by drugs, type 2 only recurs in about 10-20 percent of patients. Type 2 autoimmune pancreatitis is less common than Type 1, and typically develops in middle-aged women and men (with similar predisposition). Type 2 also tends to occur more in people with inflammatory bowel disease (i.e., Crohn disease and ulcerative colitis) as compared to Type 1
  • Treating autoimmune pancreatitis that recurs or does not respond well to medication can be medically challenging. The gastroenterologists at UC Medicine’s pancreas clinic have extensive experience managing this disease, including in patients with other complex health problems. They also stay on top of promising drug treatments, which means our patients are among the first to benefit from new therapies.

Frequently Asked Questions

Jaundice (yellow eyes and skin) is a common symptom of autoimmune pancreatitis, which is caused by blocked bile ducts. Other possible symptoms include unexplained weight loss, stomach pain, and dark urine. Imaging tests often reveal a swollen pancreas (and possibly swelling in other organs) or mass-like growths on the pancreas.

The symptoms are very similar to those experienced by people with pancreatic cancer and certain patients with chronic pancreatitis.

Given that pancreatic cancer is a very serious disease, it is understandable that patients would want to ensure they are given an accurate diagnosis before undergoing treatment. However, it’s important to recognize that autoimmune disease is a rare disease. Pancreatic cancer is much more common and always needs to be ruled out before a diagnosis of autoimmune pancreatitis can be established.

Steroids are very effective at reducing inflammation caused by autoimmune pancreatitis. In many cases, patients get better soon after taking steroids and only have to take the drug for a few weeks.

However, steroids can cause serious side effects, including high blood pressure, fluid retention, high blood sugar, and mood swings. Our gastroenterologists work to prevent and lessen side effects by tapering the dose, or amount, of steroid taken.

After treating the flare with steroids, immunosuppressive medications such as Azathioprine may also be required in some cases to prevent the disease from flaring up again in some cases, especially in those with Type 1 autoimmune pancreatitis. Alternatively, patients may require Rituximab, instead of steroids. This drug has fewer side effects than steroids and has been shown to reduce recurrences of pancreatitis.

It is not yet known what causes or raises a person’s risk for autoimmune pancreatitis. Thus, preventive measures are also unknown.

However, patients with autoimmune pancreatitis who go on to develop chronic pancreatitis may help prevent further damage to the pancreas by not smoking and avoiding excessive alcohol intake.