Autoimmune pancreatitis
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Autoimmune pancreatitis (AIP) is characterized by persistent inflammation believed to arise from an immune system malfunction wherein the pancreas becomes the target of attack. This condition has shown positive responses to treatment with steroid therapy.
AIP has two identified types, type 1 and type 2.
- Type 1 AIP: This is the common type of autoimmune pancreatitis. This type is a pancreatic manifestation of IgG4-related disease (IgG4-RD). The pancreas, bile ducts in the liver, salivary glands, kidneys, and lymph nodes are among the several organs that this disease frequently affects.
Pancreatic cancer may be misdiagnosed as Type 1 AIP. It is crucial to differentiate between the two disorders because they have similar signs and symptoms but totally distinct approaches to treating them.
- Type 2 AIP: Despite the fact that inflammatory bowel disease affects roughly one-third of persons with type 2 AIP, this type only affects the pancreas. The pancreas and pancreatic ducts are damaged by white blood cells called neutrophils. Inflammatory bowel disease affects many of the younger individuals with this type.
Symptoms
AIP usually do not cause any symptoms. If the symptoms present, a comprehensive investigation is necessary because the symptoms are similar to those with pancreatic cancer.
Signs and symptoms of pancreatic cancer may manifest as follows:
- Presence of dark urine
- Pale stools
- Jaundice, characterized by yellowing of the skin and eyes
- Upper abdominal or mid-back pain
- Nausea and vomiting
- Weakness or excessive fatigue
- Reduced appetite or feelings of fullness
- Unexplained weight loss
About 80% of individuals with type 1 AIP have painless jaundice, which is brought on by obstructed bile ducts. Recurrent episodes of acute pancreatitis can be observed in Type 2 AIP. Unlike pancreatic cancer, the presence of upper abdominal pain, which is a typical symptom, is often lacking in cases of autoimmune pancreatitis.
There are some differences between type 1 and type 2 AIP: (1 all)
- In type 1 AIP, in addition to affecting the pancreas, the condition may also impact other organs. Type 2 AIP primarily targets the pancreas; however, it is commonly linked to another autoimmune disorder known as inflammatory bowel disease.
- Type 1 AIP primarily affects men in their 60s to 70s.
- When compared to type 1 AIP, type 2 AIP has a younger age of onset and equally affects men and women.
- Type 1 AIP is more prone to relapse once treatment is stopped.
The symptoms of autoimmune pancreatitis are frequently undetectable. However, if the patient experiences troublesome signs and symptoms such as unexplained weight loss, stomach pain, or jaundice, they should consult a healthcare provider.
Causes
The cause of autoimmune pancreatitis is unknown, but like other autoimmune disorders, it is assumed to be brought on by the body’s immune system attacking healthy bodily tissue.
Risk factors
In certain instances, autoimmune pancreatitis can arise as a result of the immune system’s reaction following a bacterial infection. Moreover, individuals with existing autoimmune disorders are at an increased risk. The frequency of the two types of AIP varies across different regions worldwide. In the United States, approximately 80 percent of individuals diagnosed with autoimmune pancreatitis have type 1.
- Type 1 autoimmune pancreatitis affects patient that are over the age of 60, and commonly affects male.
- Type 2 autoimmune pancreatitis patients:
- Patient who are often over the age of 40.
- Affects female as male.
- Have an increased risk of developing inflammatory bowel diseases such as ulcerative colitis.
Diagnosis
Due to the similarities between its signs and symptoms and those of pancreatic cancer, autoimmune pancreatitis can be difficult to diagnose. On the other hand, a precise diagnosis is important. Cancer that has not been diagnosed may cause therapy to be postponed or not provided at all.
Those with AIP frequently have a generalized enlargement of the pancreas as well as having a present mass. Blood and imaging tests are required to pinpoint the diagnosis and establish the type of AIP you have.
Autoimmune pancreatitis cannot be diagnosed by a single test or distinguishing trait. Consensus diagnostic recommendations combine imaging, blood test, and biopsy results. Test may consists of the following:
- Imaging tests: CT, MRI, endoscopic ultrasound (EUS), and endoscopic retrograde cholangiopancreatography (ERCP) are a few of the tests that can be performed on the pancreas and other organs. These examinations measure the size of the pancreas and look for evidence of scarring and duct narrowing.
- Blood tests: A test for high levels of IgG4, an immunoglobulin made by the immune system, will be performed on the patient. IgG4 levels in the blood will be extremely raised in those with type 1 AIP but not typically in those with type 2 AIP.
A positive test result does not imply that the patient has the condition. IgG4 levels in the blood are also elevated in a tiny percentage of those without autoimmune pancreatitis, including some with pancreatic cancer.
- Endoscopic core biopsy: A sample of pancreatic tissue is examined in the lab during this test by pathologists. A pathologist with experience can quickly identify AIP under a microscope due to its characteristic look. A health care provider will use an endoscope, a tiny tube that is inserted via the mouth into the stomach, to remove some pancreatic tissue under ultrasound guidance.
The difficulty lies in collecting a tissue sample that is big large enough to be examined, rather than just a few cells. Results may not be definitive because this treatment is not extensively used.
- Corticosteroid trial: Steroids typically work to treat autoimmune pancreatitis; occasionally, a trial course of this medication is prescribed to confirm a diagnosis. However, this approach should ideally only be employed with expert supervision, and only in cases where there is substantial evidence to establish an autoimmune pancreatitis diagnosis. CT and an improvement in serum IgG4 levels are used to gauge how well corticosteroids are working.
Treatment
Autoimmune pancreatitis occasionally resolves on its own in a few patients. However, the majority of patients require treatment.
- Steroids: These medications control an inflammatory response and a hyperactive immune system. After a brief course of prednisolone or prednisone, symptoms associated with autoimmune pancreatitis frequently exhibit improvement. In numerous cases, individuals respond promptly and may experience significant relief. Occasionally, individuals may even show signs of improvement without requiring any treatment.
- Biliary stenting: In patients with obstructive jaundice symptoms, a healthcare provider may occasionally place a tube to empty the bile ducts (biliary stenting). But frequently, steroid therapy is all that is needed to improve jaundice. If the diagnosis is questionable, drainage may be suggested. At the time of stent placement, tissue samples and cells from the bile duct may be collected.
- Immunosuppressants and immunomodulators: In type 1 AIP, disease relapse occurs in approximately 30% to 50% of cases, while in type 2 AIP, the relapse rate is less than 10%. These relapses often necessitate additional treatment, and in certain instances, long-term management may be required.
Healthcare providers often incorporate steroid-sparing medications, which can suppress or modify the immune system, into the treatment regimen to the course of therapy to assist lessen the severe adverse effects linked to prolonged steroid use. Depending on how the patient react to steroid-sparing therapy, they might be able to completely stop taking steroids.
Rituximab, azathioprine, mercaptopurine, and mycophenolate are immunosuppressants and immunomodulators. Long-term advantages are still being researched, but they have mostly been tested on small sample sizes.
- Observation of other organ involvement: Other organ involvement, such as swollen lymph nodes and salivary glands, bile duct scarring, liver inflammation, and renal illness are also linked to type 1 AIP. The healthcare provider will continue to monitor the patient even if these symptoms might become less severe or even go away entirely with steroid therapy.
