What is Autoimmune Pancreatitis?
Autoimmune pancreatitis (AIP), sometimes known as non-alcoholic destructive pancreatitis or sclerosing pancreatitis, is a long-term condition where the pancreas becomes severely inflamed. It can cause a variety of symptoms linked to issues in the bile ducts and pancreas. More and more, it’s being understood as a rare but significant cause of recurring pancreatitis or painless yellowing of the skin and eyes (jaundice). Besides being a pancreatic disorder, AIP is increasingly suggested as part of a group of diseases where the body’s immune system attacks its own tissues (autoimmune diseases). It can occur alongside other such conditions or as a part of a group of disorders associated with a particular type of immune protein, called immunoglobin G subclass 4 (IgG4).
There are two main types of AIP:
– Type 1 is linked with IgG4 and is known as IgG4 related pancreatitis. It is characterized by heightened levels of IgG4 in the blood and an influx of IgG4 immune cells into the pancreas. This type often occurs alongside a condition called lymphoplasmacytic sclerosing pancreatitis.
– Type 2 is called idiopathic duct-centric pancreatitis. It is recognized by specific types of lesions in the pancreatic duct, which don’t contain IgG4 positive cells or have any systemic involvement.
What Causes Autoimmune Pancreatitis?
Autoimmune pancreatitis is believed to be caused by an autoimmune reaction – that is, the body’s immune system attacking its own cells. This can be seen through the presence of immune cells called lymphocytes in the pancreas. Autoimmune pancreatitis belongs to a group of diseases related to a particular type of antibody known as IgG4.
Various theories have been proposed on how the inflammation starts in autoimmune pancreatitis. Potential triggers could include bacterial infection and a phenomenon known as molecular mimicry, which occurs when the immune system mistakes its own cells for invaders due to their similar appearance. This usually happens in individuals who already have genetic risk factors and an autoimmune tendency.
Other potential contributors could be certain immune cells (T-regulatory cells) and a shift in the body’s immune response towards an increased activity of a type of immune cell called T helper 2. These changes can lead to an increased release of immune system proteins like cytokines and interleukins, which may cause inflammation and scarring (fibrosis) of tissues.
The IgG4 antibodies are thought to cause damage to tissues, both in the pancreas and throughout the body. However, our understanding of why and how IgG4-related diseases develop is still incomplete.
Risk Factors and Frequency for Autoimmune Pancreatitis
Autoimmune pancreatitis, a condition causing long-term and repeated inflammation of the pancreas, is not very common and is possibly underdiagnosed. It makes up around 2% of all cases of chronic pancreatitis, but is found in less than 1 in 100,000 people. Historically, many reports of this condition have come from Asian countries like Japan, where it’s thought to be more prevalent. This could be due to better recognition of the condition there. However, in recent years, cases have been increasing in Western countries, making it a globally recognized condition.
- Autoimmune pancreatitis is rare, possibly not diagnosed as often as it occurs.
- It constitutes about 2% of all chronic pancreatitis cases.
- Less than 1 in 100,000 people have this condition.
- Many initial reports came from Asian countries like Japan, where it might be more common.
- More recently, cases have been reported in Western countries, implying it occurs globally.
- The condition is more common in males, at a ratio of 3:1.
- The age of onset is typically over 45 years.
Signs and Symptoms of Autoimmune Pancreatitis
Autoimmune pancreatitis is a condition where the body mistakenly attacks the pancreas, resulting in inflammation. This condition can manifest various symptoms depending upon how it affects the pancreas or bile ducts. People with this condition often experience repeated episodes of abdominal pain, or sometimes episodes of pancreatitis, an inflammation of the pancreas. They may also present with obstructive jaundice, a situation where bile can’t flow normally causing a yellowing of the skin due to buildup of a substance called bilirubin.
Other general non-specific symptoms might appear, such as:
- Nausea
- Vomiting
- Loss of appetite
- Weight loss
However, these symptoms could vary based on how much the bile ducts or pancreas are involved. During a physical examination, a doctor might not find any specific symptoms apart from mild jaundice. However, it can assist in ruling out other conditions that may be causing abdominal pain.
It is also important to note that Autoimmune pancreatitis can have effects on other parts of the body, such as salivary glands, thyroid, and kidneys. This is often seen as part of systemic IgG4-related disorders, which are conditions where the immune system produces too much of a specific type of antibody called IgG4, and attacks various organs in the body.
Testing for Autoimmune Pancreatitis
If a doctor suspects that you have autoimmune pancreatitis, they will use the International Consensus Diagnostic Criteria. This includes taking images of your pancreas and the tube that connects to it, doing blood tests (including one for an antibody known as IgG4), studying tissues from your body under a microscope, and checking whether you have other specific medical conditions.
The blood tests will include a complete blood count and a comprehensive metabolic panel. These tests will also check how your liver and kidneys are working. Sometimes, people with this condition may have certain liver enzymes and bilirubin (a substance produced by the liver) levels that are higher than normal, indicating a possible obstruction in the liver.
Your doctor will probably use either a computed tomography (CT) scan or magnetic resonance imaging (MRI) to get a good look at your pancreas and the tubes connected to it, and also to rule out other conditions that might be causing your symptoms. MRI scans, along with a special type of imaging called a cholangiopancreatogram, are usually the best way to look at the size and texture of these organs, see how they react to a contrast dye, and check for any narrowings in the tubes.
Finally, if it’s possible, your doctor might do an endoscopic ultrasound of your pancreas. This procedure involves inserting a small tube with an ultrasound device at its tip through your mouth and into your stomach and small intestine. It’s really helpful because it can create detailed images, enhance images with specific techniques, and even remove a small piece of tissue for further inspection under a microscope, all at the same time.
Treatment Options for Autoimmune Pancreatitis
There’s limited information on how to treat autoimmune pancreatitis because most of the current knowledge comes from observation-based studies. Many patients seem to respond well to therapy involving corticosteroids, which helps alleviate their symptoms and lessen the overall complications of the disease. For cases where a patient is dealing with obstructive jaundice and sclerosing cholangitis, doctors recommend starting corticosteroids as soon as possible. If corticosteroids don’t seem to be helping, it could be a sign that the patient is suffering from something else, such as pancreatic cancer.
In terms of autoimmune pancreatitis, up to half of the patients might have a relapse or find it hard to stop using steroids, especially in cases where the disease is related to IgG4 and requires prolonged steroid usage or the use of other steroid-replacing drugs. In such cases, a drug called azathioprine has been found to be effective and useful in helping patients stop their steroid therapy. Patients who have biliary strictures, which are narrowings of the bile ducts, are also more likely to have a disease relapse once they stop their steroid therapy.
The use of other drugs that modify the immune system to treat frequent relapses of autoimmune pancreatitis is still a topic of discussion among medical professionals, especially for type I autoimmune pancreatitis. Because there aren’t any clear-cut guidelines for treatment yet, the best course of therapy needs to be personalized for each patient.
What else can Autoimmune Pancreatitis be?
Before starting treatment for autoimmune pancreatitis, it’s essential to make sure that the patient does not actually have pancreatic cancer. Sometimes, it can be hard to tell the difference between the two conditions based on symptoms or imaging tests alone. So, a tissue test or biopsy is often preferred to confirm the diagnosis.
In addition, other possible causes for a blocked bile duct should also be considered. These might include gallstones, bile duct cancer, pancreatic cysts, scarring, or other health issues that can block the pancreatic ducts.
What to expect with Autoimmune Pancreatitis
Autoimmune pancreatitis, a condition where the body’s immune system attacks the pancreas, usually reacts well to corticosteroid treatment and the outlook for recovery is typically positive. Most cases see considerable improvement with this type of therapy, and complications occur less frequently once treatment begins.
However, situations where autoimmune pancreatitis coexists with a pancreatic tumor are more difficult to manage. These cases can have a less favorable outcome, and often require surgical removal of part of the pancreas.
Possible Complications When Diagnosed with Autoimmune Pancreatitis
Some patients may experience repeat instances of pancreatitis, or inflammation of the pancreas. There are also instances where certain people under observation for AIP (Autoimmune pancreatitis) have developed pancreatic cancer. However, it’s not validated whether AIP can cause cancer. If the treatment isn’t effective or cancer is suspected, doctors might recommend surgery, which can have substantial risks and could possibly lead to death.
Additional complications of AIP include worsening of biliary strictures, which are narrowings in the bile ducts that can cause extreme jaundice if not treated. There could also be complications from long-term steroid treatment, problems when trying to reduce steroid usage, or other issues resulting from immune-response altering therapy.
Common Complications:
- Repeat instances of pancreatitis
- Potential development of pancreatic cancer
- Risks associated with surgery
- Worsening of biliary strictures
- Extreme jaundice
- Long-term steroid treatment complications
- Difficulty in reducing steroid usage
- Complications from immune-response altering therapy
Preventing Autoimmune Pancreatitis
People who have autoimmune pancreatitis need a comprehensive understanding of how to manage their condition. This includes a detailed explanation about their treatment options, the necessity to stick to prescribed medication, as well as the potential consequences of not treating the disease properly. They should also be informed about the possible side effects that could arise from long-term use of corticosteroid medications, such as adrenal insufficiency (a condition that effects hormone production), osteoporosis (weak and brittle bones), weight gain, osteonecrosis (bone death due to insufficient blood flow), and hyperglycemia (high blood sugar).
