Written by Sumiran Racherla, MD. Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.

A rheumatologist, a doctor who treats immune system diseases, most often leads care for IgG4-related disease. People with this disease need close follow-up with doctors who know it well. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.

IgG4-related disease, also called IgG4-RD, is an immune-mediated condition. This means that disease in organs happens as the result of an abnormally regulated immune system. Some people have disease in only one organ. Others have disease that affects several organs at the same time. The disease seems to be capable of affecting every organ.

Organs that are often involved include the lungs, kidneys, pancreas, bile ducts, thyroid gland, and aorta. The glands that make tears and saliva are also often involved. The classic patient is a middle-aged to elderly person who is more likely to be male than female. In rare cases, the disease also affects children.

Symptoms

Many people have no signs or symptoms for months or even years before the diagnosis is made. Organ damage can happen while a person feels well. The disease can often appear as a mass that looks like cancer. Because so many organs can be affected, the symptoms differ from person to person. Common symptoms include:

  • Tiredness (fatigue), weight loss, and headaches.
  • Bulging of one or both eyes.
  • Bulges on the sides of the face or below the chin.
  • Inflammatory tissue in the thyroid.
  • Large vessel vasculitis, which is inflammation in the blood vessel wall.
  • Shortness of breath.
  • Enlarged kidneys, or blockage of urine flow from the kidney.
  • Belly pain and painless jaundice, a yellow tint to the skin or eyes.

Causes and who gets it

Experts believe that IgG4-related disease is caused by autoimmune mechanisms. It is still unclear if IgG4 harms the body or protects it.

How doctors diagnose it

Features of IgG4-RD include the following.

  • Swelling, nodules, or wall thickening on imaging tests.
  • High IgG4 levels in the blood.
  • Many IgG4-bearing plasma cells, which are a type of immune cell, in the affected organs.
  • Fibrosis, or scar-like tissue, in the affected organs.

Doctors must tell it apart from cancer and similar conditions. A tissue sample can be hard to get from some organs, such as the pancreas. For those organs, doctors use special diagnostic criteria made for each organ.

Treatment

If it is found before serious organ damage, it typically responds well to treatment. But long-term treatment is needed. Glucocorticoids, which are steroid medicines, are typically the first treatment. Nearly all patients respond to glucocorticoids. But about 40% of them do not reach complete remission, or the disease comes back within one year. The disease often comes back after glucocorticoids are stopped.

Rituximab is often an excellent treatment for IgG4-RD. It is not typically linked to many of the side effects seen with glucocorticoids. Not every form of the disease needs treatment right away. Simple observation is enough in some cases. After the first course of treatment, patients with high disease activity may benefit from maintenance therapy.

Experts once thought the disease was reversible with a good outlook. Over time, it can sometimes lead to advanced stages with organ dysfunction.

When to see a doctor

It is important to seek medical attention for symptoms early and begin treatment. The disease can damage organs.

Call 911 or go to the emergency room if you have severe trouble breathing, chest pain, or fainting. Also call 911 for sudden severe belly or back pain or a sudden change in mental state.

How a direct primary care or concierge doctor fits in

A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. People with IgG4-RD also need to broaden their own knowledge of this condition.

Common questions

No. It is an immune-mediated condition. But it can often appear as a mass that mimics cancer.

It seems to be capable of affecting every organ. Some people have disease in only one organ, and others have it in several organs at the same time.

Yes. The disease often comes back after glucocorticoids are stopped.

No. Not all forms of IgG4-RD need immediate treatment, and simple observation is enough in some cases.

Sources

  1. American College of Rheumatology - IgG4-Related Disease (IgG4-RD)
  2. NCBI PubMed Central - Immunoglobulin G4-related Disease: An Overview

Medical Disclaimer

This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.