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Understanding IgG4-Related Disease
Lessons from the First 20 Years
IgG4-related disease (IgG4-RD) is a long-term immune condition that causes inflammation and scarring (fibrosis) in one or more organs. It was first recognized about 20 years ago, and since then, researchers and patients have helped uncover how it develops, how it affects the body, and how it can be effectively treated.
What Is IgG4-RD?
IgG4-RD happens when parts of the immune system—especially certain white blood cells—become overactive and trigger widespread inflammation. This can cause swelling, lumps, or thickening in organs such as:
- The pancreas
- Salivary and tear glands
- Kidneys and lungs
- Thyroid or lymph nodes
- Large blood vessels like the aorta
Because it can appear almost anywhere in the body, it has often been mistaken for cancer, infection, or other autoimmune diseases.
1. It’s More Than Just Inflammation — It’s a Form of Vasculitis
Doctors now know that IgG4-RD can involve inflammation of the blood vessels themselves. This “vasculitis” can affect vessels large and small, sometimes causing narrowing or blockage. Understanding this helps doctors connect what might look like separate organ problems into one underlying diagnosis.
2. It Often Affects Men More — and Sometimes More Severely
Unlike many autoimmune diseases, IgG4-RD is more common in men (about twice as often as in women). Men are more likely to have deeper organ involvement—like the pancreas, kidneys, or blood vessels—while women may have disease in the salivary or tear glands.
3. Diagnosis Takes a Team Effort
There’s no single test that can confirm IgG4-RD. Doctors look for a pattern across:
- Symptoms and imaging (like swelling or tissue thickening)
- Blood tests (especially IgG4 levels)
- Biopsy findings, which may show a characteristic pattern of immune cells and fibrosis
Because these findings can also occur in other conditions, diagnosis usually involves collaboration between rheumatologists, pathologists, and radiologists.
4. Blood IgG4 Levels Can Help Track Activity
Many—but not all—patients have high blood IgG4 levels. This test can help monitor disease activity or predict relapses, but normal levels don’t rule it out. It’s one piece of the puzzle, not the whole picture.
5. Early Treatment Prevents Lasting Damage
Prompt treatment is key. Inflammation can lead to scarring that’s harder to reverse later.
- Steroids (like prednisone) are often the first treatment and usually bring rapid relief.
- Rituximab and other B-cell–targeting biologics are highly effective for many people, often helping to maintain remission while reducing steroid use.
- Newer therapies such as inebilizumab and obexelimab are being studied and may offer even safer, more durable control.
The Takeaway
IgG4-RD is a complex but increasingly treatable condition. The last two decades have transformed it from a medical mystery into a manageable chronic disease. With early recognition, coordinated care, and modern therapies, most people can live full lives and protect their organ function for years to come.
