IgG4-related disease (IgG4-RD) is a rare condition that causes inflammation in different parts of the body. It can affect the pancreas, salivary glands, tear glands, kidneys, lungs, and other organs. In some people, the disease also causes scar tissue to form. As a result, affected organs may not work properly.

The condition often develops slowly. Therefore, some people may not notice symptoms in the early stages. However, early diagnosis and appropriate treatment can help control inflammation and reduce the risk of organ damage.

In this guide, you will learn who can develop IgG4-related disease, which symptoms to watch for, what doctors know about possible triggers, how a biopsy helps with diagnosis, and which treatments may help.

What Is IgG4-Related Disease?

IgG4-related disease is an immune-mediated condition. This means that an abnormal immune response contributes to inflammation in the body’s tissues.

The disease can affect one organ or several organs at the same time. Doctors may find swelling, inflammation, and fibrosis in affected tissues. Fibrosis means the formation of scar tissue. Over time, this scarring can interfere with normal organ function.

IgG4 is a type of antibody produced by the immune system. Some people with IgG4-RD have high levels of this antibody in their blood. However, a high IgG4 level alone does not confirm the disease.

Because the condition can resemble cancer, infection, or other inflammatory diseases, doctors use several tests before making a diagnosis.

Who Gets IgG4-Related Disease?

IgG4-related disease can affect adults of different ages. Doctors diagnose it more often in middle-aged and older adults, although younger adults can also develop it.

The condition can affect people of any sex. Its symptoms and severity depend on which organs the disease involves.

Researchers do not yet know exactly why some people develop IgG4-RD. Genetic factors and changes in immune function may play a role, but scientists need more research to understand the condition fully.

What Causes IgG4-Related Disease?

Researchers have not identified one exact cause of IgG4-related disease. However, the immune system plays an important role.

Several factors may help explain how the disease develops:

• Immune system changes: Certain immune responses may contribute to inflammation in body tissues.
• Inflammation: Immune cells collect in affected organs and may damage normal tissue.
• Fibrosis: Long-lasting inflammation can lead to scar tissue.
• Possible genetic factors: Researchers are studying whether certain genetic differences increase susceptibility.

Some people with IgG4-RD have elevated blood IgG4 levels. Nevertheless, some affected people have normal levels, and other conditions can also cause elevated results.

Common Symptoms of IgG4-Related Disease

Symptoms depend on which organs the disease affects. Some people develop painless swelling, while others notice pain or changes in organ function.

Common symptoms may include:

• Swelling of the salivary or tear glands
• Painless swelling around the face or neck
• Abdominal pain or discomfort
• Yellowing of the skin or eyes
• Unexplained weight loss
• Dry mouth or dry eyes
• Changes in kidney function
• Persistent cough or breathing difficulties

These symptoms can occur in many other conditions. Therefore, a healthcare professional must assess them before making a diagnosis.

Symptoms by Affected Organ

1. Pancreas

IgG4-related disease can affect the pancreas and cause a condition called type 1 autoimmune pancreatitis. Symptoms may include abdominal discomfort, jaundice, and unexplained weight loss.

2. Salivary and Tear Glands

The disease may cause swelling around the cheeks, jaw, or eyes. Some people also experience dry mouth or dry eyes.

If you experience ongoing dryness or other eye symptoms, read our guide to eye health and common eye problems. It explains common eye conditions and when to seek professional care.

3. Bile Ducts

Inflammation around the bile ducts can block the flow of bile. As a result, a person may develop jaundice, dark urine, pale stools, or itching.

4. Kidneys

IgG4-RD can cause inflammation in kidney tissue. In some cases, kidney function declines without obvious symptoms at first. Blood and urine tests can help doctors identify these changes.

5. Lungs

When the disease affects the lungs, symptoms may include a persistent cough, shortness of breath, or chest discomfort. Some people have no noticeable symptoms, and doctors discover the problem during imaging.

6. Other Organs

The disease can also affect tissues around the aorta, the lining around certain organs, and other body structures. Symptoms depend on the location and severity of inflammation.

What Are IgG4-RD Flare Symptoms?

A flare means that disease activity has increased or symptoms have returned or worsened. Not everyone experiences clear flares, and symptoms can vary from person to person.

Possible warning signs include:

• New or increasing swelling
• Worsening abdominal discomfort
• New jaundice or itching
• Increasing cough or breathlessness
• Changes in kidney function tests
• New symptoms linked to an organ already affected by the disease

However, these symptoms do not always mean that IgG4-RD has flared. Infection, medication effects, and other conditions can cause similar problems.

Contact your healthcare professional if your symptoms change. Seek urgent medical care for severe breathing difficulty, confusion, severe abdominal pain, or rapidly worsening jaundice.

What Triggers an IgG4-RD Flare?

Doctors do not fully understand what triggers IgG4-RD flares. Researchers continue to study the immune responses and other factors that influence disease activity.

At present, there is no confirmed list of triggers that applies to every patient. A flare may occur even when a person cannot identify a clear cause.

Still, patients can take practical steps to manage their health:

• Take prescribed medicines as directed.
• Attend follow-up appointments.
• Tell your doctor about new symptoms.
• Discuss infections and medication changes with your healthcare team.
• Avoid stopping prescribed steroids or other medicines without medical advice.

Keeping a symptom diary may also help. Record new symptoms, their duration, medication changes, and other relevant events. Your doctor can review this information during follow-up visits.

How Do Doctors Diagnose IgG4-Related Disease?

Doctors use several types of evidence to diagnose IgG4-RD. No single blood test or scan can confirm every case.

1. Medical History and Physical Examination

First, the doctor asks about your symptoms, how long they have lasted, and whether they have changed. The doctor may also examine swollen glands and look for signs of organ involvement.

2. Blood Tests

Blood tests may measure IgG4 levels and check for inflammation or organ problems. Depending on your symptoms, doctors may also test liver function, kidney function, and other markers.

An elevated IgG4 level can support the diagnosis, but it is not enough on its own. Some people without IgG4-RD have high levels, while some patients with the disease have normal levels.

3. Imaging Tests

Doctors may use ultrasound, CT scans, or MRI to examine affected organs. These tests can show swelling, masses, thickened tissues, or changes in organ structure.

Imaging also helps doctors check whether the disease affects more than one organ and identify a suitable site for a biopsy.

4. Biopsy

A biopsy involves taking a small tissue sample for examination. A pathologist looks for patterns of inflammation and fibrosis that may support IgG4-RD.

Doctors may recommend a biopsy when they need to distinguish IgG4-RD from cancer, infection, or another inflammatory disease. However, the need for a biopsy depends on the clinical situation and the organ involved.

5. Ruling Out Other Conditions

Several diseases can look similar to IgG4-RD. These include certain cancers, infections, autoimmune conditions, and other inflammatory disorders.

For this reason, doctors consider the full clinical picture rather than relying on one test result.

Accurate evaluation is especially important when imaging shows an unusual mass or organ enlargement. You can also read our guide to cancer diagnosis and care to learn more about medical evaluation and why doctors may use imaging and biopsies to investigate suspicious changes.

What Is a Biopsy for IgG4-RD?

A biopsy can help doctors determine whether tissue changes fit IgG4-related disease. It may also help rule out other serious conditions, including cancer.

During the procedure, a healthcare professional collects a small tissue sample from an affected area. The method depends on the organ and the location of the abnormal tissue.

For example, doctors may use a needle biopsy or collect a sample during an endoscopic procedure. In other cases, they may need a different approach.

A pathologist examines the sample under a microscope. The report may describe immune cells, fibrosis, and the number or pattern of IgG4-positive plasma cells.

Doctors interpret these findings alongside symptoms, blood tests, and imaging results. A high number of IgG4-positive cells alone does not prove IgG4-RD.

How Is IgG4-Related Disease Treated?

Treatment depends on the affected organs, the severity of the disease, and the risk of permanent damage. Some people need treatment soon after diagnosis, while others may need careful monitoring.

1. Corticosteroids

Doctors often use corticosteroids, such as prednisone, to control active inflammation. These medicines can reduce swelling and improve symptoms in many patients.

However, corticosteroids can cause side effects, especially with prolonged use. Possible problems include increased blood sugar, weight gain, high blood pressure, bone loss, and a higher risk of infection.

For that reason, patients should take these medicines only under medical supervision. Do not start, change, or stop treatment without advice from your healthcare professional.

2. Other Immune-Targeting Medicines

Some patients need other medicines to control the disease or reduce the chance of relapse. Depending on the case, specialists may consider medicines such as rituximab or other steroid-sparing treatments.

The choice depends on disease activity, previous treatment, other health conditions, and the organs involved. A specialist should explain the expected benefits and risks.

3. Monitoring and Follow-Up

Regular follow-up helps doctors check whether treatment is working and whether the disease has returned. Your care team may repeat blood tests, imaging, or other assessments based on your condition.

Follow-up also helps identify medication side effects and changes in organ function.

4. Treatment for Organ Complications

Some people need additional treatment for problems caused by inflammation or scarring. For example, a blockage in the bile ducts may require a procedure, while kidney involvement may require closer monitoring by a specialist.

Treatment cannot always reverse established scar tissue. Therefore, early recognition and appropriate care are important.

Can IgG4-Related Disease Cause Complications?

Yes. If the disease remains active, inflammation and fibrosis may damage affected organs.

Possible complications include:

• Reduced kidney function
• Blockage of the bile ducts
• Problems with pancreatic function
• Narrowing or damage involving blood vessels
• Persistent swelling or reduced function in affected glands
• Permanent organ damage from advanced fibrosis

The risk depends on which organs are involved and how early doctors identify and treat the disease. Regular follow-up can help detect complications before they become more serious.

Living With IgG4-Related Disease

Living with a chronic condition can feel difficult, especially when symptoms change over time. However, a clear treatment plan and regular medical care can help you manage the condition.

Consider these practical steps:

• Keep a record of your symptoms and appointments.
• Take medicines exactly as prescribed.
• Complete recommended blood tests and scans.
• Report new or worsening symptoms promptly.
• Ask your doctor about medication side effects and infection risks.
• Discuss supplements and over-the-counter medicines before using them.

There is no single diet or lifestyle change proven to cure IgG4-RD. A balanced diet, regular activity suited to your health, and adequate sleep can support general well-being, but they cannot replace medical treatment.

Frequently Asked Questions

1. Is IgG4-related disease a rare condition?

Yes. IgG4-related disease is considered rare. However, doctors may miss some cases because its symptoms can resemble those of other conditions.

2. Is IgG4-related disease cancer?

No. IgG4-RD is an immune-mediated inflammatory condition, not a type of cancer. However, some cancers can look similar, so doctors may need imaging or a biopsy to distinguish them.

3. Can IgG4-related disease affect multiple organs?

Yes. The disease can affect one or several organs. Commonly affected areas include the pancreas, salivary glands, tear glands, kidneys, lungs, and bile ducts.

4. Does a high IgG4 blood level confirm the disease?

No. A high level may support the diagnosis, but it cannot confirm IgG4-RD by itself. Doctors also consider symptoms, imaging, and sometimes biopsy results.

5. What are the common symptoms of an IgG4-RD flare?

Possible signs include new swelling, worsening abdominal discomfort, jaundice, breathing symptoms, or changes in organ function. However, these symptoms can have other causes, so medical assessment is important.

6. Is a biopsy always necessary for IgG4-RD?

No. The need for a biopsy depends on the affected organ, the available test results, and the need to rule out other conditions. Your doctor can explain whether a tissue sample is appropriate for your case.

7. Can IgG4-related disease be cured?

Treatment can control inflammation and may bring the disease into remission. However, some patients experience relapses, and existing organ damage may not fully reverse. Long-term monitoring may be necessary.

8. Which doctor treats IgG4-related disease?

Depending on the organs involved, care may involve a rheumatologist, gastroenterologist, nephrologist, pulmonologist, or another specialist. Some patients benefit from a team of specialists.

Final Thoughts

IgG4-related disease can affect different organs and may cause inflammation, swelling, and scar tissue. Its symptoms often resemble other illnesses, so doctors need to assess several types of evidence before making a diagnosis.

The good news is that treatment can control disease activity in many patients. Early assessment, appropriate medication, and regular follow-up can help reduce the risk of complications.

If you notice persistent swelling, unexplained jaundice, breathing problems, or other concerning symptoms, consult a qualified healthcare professional. Do not rely on a single blood test or attempt to treat the condition yourself.

References

1. Deshpande V, et al. Consensus statement on the pathology of IgG4-related disease. Modern Pathology. 2012.
2. Khosroshahi A, et al. International consensus guidance statement on the management and treatment of IgG4-related disease. Arthritis & Rheumatology. 2015.
3. Stone JH, Zen Y, Deshpande V. IgG4-related disease. New England Journal of Medicine. 2012.

Medical disclaimer: This article is for general educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your symptoms or treatment options.