IgG4-Related Disease

What is IgG4-related disease?

IgG4-related disease is a chronic (long-lasting) condition in which the immune system causes inflammation and scarring in one or more organs. It is sometimes written as IgG4-RD. The name comes from a type of antibody called immunoglobulin G4, or IgG4. Antibodies are proteins made by the immune system to fight infection. In this disease, large numbers of immune cells that produce IgG4 collect inside tissues, along with a distinctive pattern of scar tissue. Over time this can cause an organ to swell, form a mass, or stop working properly.

The condition was only recognized as a single disease in the early 2000s. Before that, doctors treated its many forms as separate illnesses with different names, such as autoimmune pancreatitis (inflammation of the pancreas), Mikulicz disease (swelling of the tear and salivary glands), and retroperitoneal fibrosis (scarring behind the abdominal lining). Researchers later found that these conditions shared the same appearance under the microscope and often occurred together in the same person.

IgG4-related disease can affect almost any organ. The most commonly involved sites include the pancreas, the bile ducts (tubes that carry digestive fluid from the liver), the salivary glands, the tear glands, the tissue around the eyes, the kidneys, the lungs, the lymph nodes, the aorta (the main artery leaving the heart), and the tissue in the back of the abdomen. Many people have more than one organ involved, either at the same time or at different points in their lives.

The disease is considered rare, although exact numbers are uncertain because it is often missed or mistaken for other conditions. It most often appears in middle-aged and older adults. Forms that affect the pancreas, bile ducts, and kidneys are seen more often in men, while forms that affect the head and neck glands appear to affect men and women more equally. Children are rarely affected. In many hospital groups, including Acibadem, care is coordinated by rheumatology (the specialty that treats immune and inflammatory diseases), working with other specialists depending on which organs are involved.

IgG4-related disease symptoms

IgG4-related disease symptoms depend heavily on which organs are affected. This is one reason the condition can be hard to recognize. Some people feel generally well and are found to have the disease only after a scan or blood test done for another reason. Others develop noticeable swelling or organ problems. Symptoms often develop slowly over months rather than suddenly. Fever and severe illness are uncommon, although fatigue and weight loss can occur.

Common signs and symptoms include:

• Painless swelling of the glands in the face, such as the salivary glands under the jaw or in the cheeks, or the tear glands in the upper outer part of the eyelid
• Bulging or puffy eyes, or double vision, when tissue around the eyes is involved
• Jaundice (yellowing of the skin and whites of the eyes), dark urine, and pale stools when the pancreas or bile ducts are affected
• Upper abdominal discomfort or unexplained weight loss
• New diabetes or worsening blood sugar control, because the inflamed pancreas may make less insulin
• Back or flank pain when the tissue behind the abdomen or the kidneys is involved
• Swollen lymph nodes in the neck, armpits, or elsewhere
• Cough or shortness of breath if the lungs or airways are affected
• Headache, vision changes, or hormone problems if the disease affects the pituitary gland (a small hormone gland at the base of the brain) or the lining of the brain
• Dry mouth or dry eyes, although this is usually milder than in some other gland conditions

Doctors sometimes group the disease into patterns. A head-and-neck pattern mainly involves the tear glands, salivary glands, and eye area. A pancreas-and-liver pattern involves the pancreas and bile ducts and often causes jaundice. A retroperitoneal-and-aortic pattern causes scarring around the aorta and the tubes that drain the kidneys, which can block urine flow. A widespread pattern may involve many organs at once. In early stages, inflammation dominates and organs may swell. In later stages, scar tissue can become more prominent and may not fully shrink even when inflammation is controlled.

Causes and risk factors

The exact IgG4-related disease causes are not known. It is understood as an immune-mediated condition, meaning the body’s own immune system drives the inflammation. Researchers have found that certain immune cells, including specific types of T cells (a kind of white blood cell) and B cells (the cells that make antibodies), gather in affected tissues and appear to signal one another to keep the inflammation going and to lay down scar tissue.

It remains unclear whether the IgG4 antibody itself causes damage or is simply a marker of the process. Some researchers think IgG4 may actually be produced as part of an attempt to calm inflammation. Because of this uncertainty, the disease is not classified as a classic autoimmune disease in the way that, for example, lupus is, although it shares some features.

Several factors have been studied as possible contributors, though none is proven to cause the disease on its own:

• Genetic factors: certain gene variations involved in immune regulation appear more common in people with the disease, suggesting inherited susceptibility may play a role.
• Allergic tendency: a history of allergies, asthma, eczema, or nasal polyps is reported more often in people with IgG4-related disease, and blood markers of allergy are frequently raised.
• Environmental or occupational exposures: some studies have noted more frequent long-term exposure to dusts, solvents, or industrial materials among affected people, but this link is not confirmed.
• Infections: it has been suggested that a past infection might trigger the immune response in susceptible people, but no specific germ has been identified.

Risk factors that appear to increase the chance of being diagnosed include being over 50 years of age, being male (for the pancreatic, biliary, and kidney forms), and having a personal history of allergic conditions. The disease is not known to be contagious, and it is not caused by diet or lifestyle in any proven way. Because the causes are not understood, there is currently no known way to prevent it.

IgG4-related disease diagnosis

IgG4-related disease diagnosis can be challenging because the condition can look like cancer, infection, or other inflammatory diseases. A swollen pancreas, for example, may closely resemble pancreatic cancer on a scan. For this reason, doctors usually combine several types of evidence before confirming the diagnosis, and they take care to rule out other explanations first.

The main steps typically include:

• Medical history and physical examination: your doctor will ask about swelling, jaundice, allergies, and past episodes that might fit the pattern, and will examine the glands, eyes, abdomen, and lymph nodes.
• Blood tests: a serum IgG4 level is often measured. It is raised in many, but not all, people with the disease, and it can also be raised in other conditions. A normal level therefore does not rule the disease out, and a high level alone does not confirm it. Other tests may check liver function, kidney function, blood sugar, markers of inflammation, and levels of certain immune proteins called complement, which are sometimes low.
• Imaging: computed tomography (CT, a detailed X-ray scan), magnetic resonance imaging (MRI, a scan using magnetic fields), and ultrasound can show swollen organs, masses, narrowed bile ducts, or scar tissue around blood vessels. A PET scan (positron emission tomography, which highlights active inflammation) is sometimes used to map all involved organs and to guide where to take a biopsy.
• Biopsy: this is the most important test in many cases. A small sample of affected tissue is removed with a needle or during a minor procedure and examined under a microscope by a pathologist. Three features support the diagnosis: a dense collection of immune cells rich in IgG4-producing plasma cells, a swirling or cartwheel-like pattern of scar tissue called storiform fibrosis, and blocked small veins known as obliterative phlebitis. A biopsy also helps exclude cancer and lymphoma, which is especially important.
• Classification criteria: international expert groups have published criteria that combine clinical findings, blood results, imaging, and biopsy features into a scoring system, and that list findings which point away from the diagnosis. These criteria were designed mainly for research, but doctors may use them to support their judgment.

In some situations a biopsy is difficult or risky, for example when the disease affects the tissue around the aorta or deep behind the abdomen. In such cases doctors may rely more on imaging, blood tests, involvement of other more accessible organs, and the response to treatment. Because so many organs can be involved, diagnosis often requires a team that may include a rheumatologist, a gastroenterologist (digestive system specialist), an eye specialist, a kidney specialist, a radiologist, and a pathologist. Ongoing care is commonly coordinated through a Rheumatology Department.

IgG4-related disease treatment options

The goals of IgG4-related disease treatment are to reduce inflammation, protect organs from permanent damage, relieve symptoms, and prevent relapses. Treatment is tailored to which organs are affected and how severely. Not every case needs immediate medication.

Observation. If the disease involves only a lymph node or a mildly swollen gland and is not threatening any organ’s function, your doctor may recommend careful monitoring with regular check-ups, blood tests, and scans rather than starting medication right away. This approach avoids side effects in people who may not need treatment.

Glucocorticoids (steroid medicines). Steroid tablets such as prednisone are the usual first treatment when an organ is at risk. Most people respond quickly, often within weeks, with shrinking of swollen tissues and improvement in blood tests. The dose is typically started at a moderate level and gradually reduced over several months. Side effects can include weight gain, mood changes, raised blood sugar, high blood pressure, thinning of the bones, and increased infection risk, so doctors aim to use the lowest effective dose for the shortest necessary time. Some doctors continue a low maintenance dose for a period to lower the chance of relapse.

Steroid-sparing medicines. Because relapses are common when steroids are reduced or stopped, other medicines that calm the immune system are often added. These include drugs such as azathioprine, mycophenolate, and methotrexate. They allow the steroid dose to be lowered while keeping the disease under control. Regular blood tests are needed to monitor for side effects on the liver, kidneys, or blood counts.

B-cell targeting therapy. Rituximab is a medicine given by intravenous infusion (a drip into a vein) that removes B cells, the immune cells that develop into antibody-producing plasma cells. It is often used when steroids cannot be tolerated, when the disease returns repeatedly, or when the disease is severe. It is generally given as a course of infusions, and repeat courses may be needed. Newer targeted therapies are under study in clinical trials.

Procedures. When scar tissue or swelling blocks a duct or tube, mechanical relief may be needed. Examples include placing a stent (a small tube) in a narrowed bile duct to relieve jaundice, or placing a stent in the ureter (the tube from kidney to bladder) when scar tissue behind the abdomen blocks urine flow. These procedures treat the blockage but do not treat the underlying inflammation, so they are usually combined with medication.

Surgery. Surgery is not a primary treatment for IgG4-related disease. It is occasionally performed to remove a mass when cancer cannot be excluded, or to relieve a blockage that cannot be managed with a stent. In some cases the diagnosis is only made after surgery, when the removed tissue is examined.

Supportive care. Depending on the organs involved, treatment may also include managing diabetes caused by pancreatic damage, replacing pancreatic digestive enzymes, replacing hormones if the pituitary gland is affected, protecting bone health during steroid therapy, and keeping vaccinations up to date because immune-suppressing medicines increase infection risk.

Living with IgG4-related disease and outlook

For many people, IgG4-related disease responds well to treatment, and swollen organs return toward normal size. However, it is generally considered a relapsing condition, meaning it can come back after a period of control, sometimes in a different organ than before. Long-term follow-up is therefore usually recommended even when a person feels well. Follow-up typically involves periodic blood tests and imaging, along with attention to any new swelling or symptoms.

The outlook depends largely on how much permanent damage occurred before treatment started. Inflammation usually improves with medication, but established scar tissue may not fully reverse. When the disease has damaged the pancreas, bile ducts, or kidneys over a long time, some loss of function may persist. Early recognition and treatment are thought to give the best chance of preserving organ function, which is why awareness of the condition matters.

Living with the disease often means balancing the benefits of medication against side effects. People taking steroids or immune-suppressing drugs may be advised to monitor blood pressure and blood sugar, take steps to protect their bones, avoid contact with people who have active infections where possible, and report fevers promptly. A healthy diet, regular physical activity as tolerated, and not smoking are generally encouraged for overall health, although they do not treat the disease itself.

Some studies have noted that people with IgG4-related disease may have a somewhat higher chance of developing certain cancers, particularly lymphoma, though the strength of this link is still being studied. Your doctor may keep this in mind during follow-up. It can also help to keep a written record of affected organs, treatments, and dates of relapses, as this information is useful when seeing new specialists. Because the condition is uncommon, some people find it helpful to connect with patient organizations for rare diseases.

Frequently asked questions

Is IgG4-related disease a type of cancer?

No. IgG4-related disease is an inflammatory condition, not a cancer. However, it can form masses and swell organs in ways that closely resemble cancer on scans, and it is often first suspected to be a tumor. This is why a biopsy is usually needed to rule out cancer before the diagnosis is confirmed. In some cases, people have undergone surgery for suspected cancer before the true diagnosis was made.

What are the first IgG4-related disease symptoms people notice?

Early symptoms vary widely. Common first signs include painless swelling of the glands under the jaw or near the eyes, puffy eyelids, yellowing of the skin from a blocked bile duct, unexplained weight loss, or new diabetes. Some people have no symptoms and the condition is found incidentally on a scan. Because symptoms can be subtle and slow to develop, the disease is often present for some time before it is recognized.

What causes IgG4-related disease and can it be prevented?

The precise cause is not known. It is understood as an immune-mediated condition in which certain immune cells drive inflammation and scarring. Genetic susceptibility, an allergic tendency, and possibly environmental exposures may contribute, but none has been proven to cause the disease alone. Because the cause is unclear, there is currently no known way to prevent it, and it is not caused by anything a person did or did not do.

How is IgG4-related disease diagnosis confirmed?

Doctors usually combine several types of evidence: symptoms and examination findings, blood tests including the serum IgG4 level, imaging such as CT or MRI, and most importantly a biopsy showing the characteristic pattern of IgG4-rich immune cells and scar tissue. No single test is sufficient on its own. A raised IgG4 level supports the diagnosis but can occur in other conditions, and a normal level does not exclude the disease.

What is the most common IgG4-related disease treatment?

Steroid tablets such as prednisone are the usual first treatment, and most people respond within weeks. Because the disease often returns when steroids are reduced, doctors frequently add other immune-calming medicines or use rituximab, particularly for severe or repeatedly relapsing disease. Procedures such as stents may be needed to relieve blockages. Mild disease that is not threatening an organ is sometimes monitored without medication.

Can IgG4-related disease be cured?

There is currently no cure, but the disease can often be controlled well with treatment, and many people achieve long periods of remission (a time when the disease is inactive). Relapses are common, so long-term follow-up is generally recommended. The extent of permanent organ damage depends largely on how long the disease was active before treatment began.

Which doctor treats IgG4-related disease?

Care is commonly led by a rheumatologist, a specialist in immune and inflammatory diseases, working with other specialists depending on the organs involved, such as a gastroenterologist for the pancreas and bile ducts, a nephrologist for the kidneys, or an ophthalmologist for the eyes. A pathologist and a radiologist are also important in confirming the diagnosis.

When to see a doctor

Anyone with persistent, unexplained swelling of the glands in the face or neck, yellowing of the skin or eyes, or an unexplained mass found on a scan should be evaluated by a doctor. Because IgG4-related disease can mimic cancer and can damage organs quietly, these findings should not be ignored even if they are painless.

People already diagnosed with IgG4-related disease should contact their care team if they notice new swelling, returning symptoms, or side effects from medication. Seek urgent medical attention if any of the following red-flag signs occur:

• Rapidly worsening yellowing of the skin or eyes, especially with dark urine, pale stools, fever, or chills, which may signal a blocked or infected bile duct
• Severe abdominal or back pain, particularly if sudden
• Sudden loss of vision, double vision, or severe eye pain or bulging
• Passing very little urine, or swelling of the legs, which may indicate the kidneys or ureters are blocked
• Fever or signs of infection while taking steroid or immune-suppressing medicines
• Chest pain, severe shortness of breath, or fainting, which may relate to aortic or lung involvement
• Severe headache with confusion, weakness, or seizures
• Symptoms of very high blood sugar, such as extreme thirst, frequent urination, and drowsiness

These symptoms do not necessarily mean the disease has worsened, but they require prompt assessment so that serious complications can be identified and treated early.