IgG4-related disease (IgG4-RD, systemic)

IgG4-related disease is an immune-mediated condition in which inflammation and fibrous, tumor-like swelling build up in one or more organs, often paired with high blood levels of a specific antibody subtype called IgG4. Current understanding describes a T-helper type 2 dominant immune response that drives this process, with T cells, B cells, plasma cells, and innate immune signaling all contributing to the tissue swelling and scarring. It most often affects the pancreas, tear and salivary glands, the tissue behind the abdomen, kidneys, and lungs, and can mimic cancer or infection on imaging, which makes diagnosis a careful process of ruling out other causes.

IgG4-related disease was only recognized as a distinct entity in the past two decades, so epidemiologic knowledge is still described as limited, though research notes it appears more common in men. Most people respond well to glucocorticoid treatment initially, and relapse during tapering is common, so ongoing monitoring matters.

Common signs

Symptoms depend on which organs are involved and may include painless swelling of the salivary or tear glands, jaundice or abdominal discomfort from pancreas or bile duct involvement, a mass or lump, fatigue, and weight loss. Some people feel relatively well and the disease is found through imaging done for an unrelated reason.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.