A systemic disease that is characterised by fibroinflammatory infiltration of various organs, including by plasma cells that express IgG4 (immunoglobulin G subclass 4).
- Immunoglobulin G4-related disease (IgG4-RD) is an immunologic fibro-inflammatory systemic disease
- First associated with sclerosing autoimmune pancreatitis in 2001.
- The organs or structures are infiltrated by inflammatory IgG4-positive plasma cells
- If untreated, result in fibrosis and permanent organ damage. Can involve any structure
- Coronary artery stenosis - chest pain
- Pericardial thickening - chest pain
- Chronic subdural disease
- History of autoimmune disease
- Abdominal pain and pancreatitis
- Salivary gland disease enlarged with lymphadenopathy
- Skin manifestations
- Fluorodeoxyglucose (FDG)
- Biopsy: Immunohistochemistry should demonstrate plasma cells that stain for IgG4. IgG4+ plasma cells must account for more than 40% of IgG+ plasma cells. A serum IgG4 level >135 mg/dL is supportive of the diagnosis
- Steroids with one series documenting disease remission in 90% of cases.
- Refractory disease, anti-rheumatic drugs can be considered (i.e. azathioprine, methotrexate or mycophenolate mofetil), though consensus guidelines highlight the lack of data supporting this.
- Serial measurements of IgG4 levels and imaging is helpful to ensure disease quiescence after initiation of therapy and during the maintenance period.