IgG4-related disease
IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder in which tumefactive, IgG4-plasma-cell-rich lesions with storiform fibrosis and obliterative phlebitis enlarge and scar multiple organs, mimicking malignancy at every site. Diagnosis requires biopsy, since a raised serum IgG4 is neither necessary nor sufficient, and first-line treatment is high-dose glucocorticoids with rituximab for relapsing or refractory disease.
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What this article covers
- Overview
Definition: IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder in which one or multiple organs develop tumefactive infiltration by IgG4-bearing plasmablasts and other lymphocytes…
- Epidemiology
Organ range: almost any organ can be involved, from pancreas and biliary tract to salivary/lacrimal glands, orbit, thyroid, dura, pituitary, aorta, kidney, and retroperitoneum (detailed under Clinical features).
- Risk factors
No established genetic or environmental risk factor: no validated predisposing exposure, familial pattern, or genetic marker is established; IgG4-RD is treated as idiopathic.
- Pathophysiology
Tissue infiltration: affected organs accumulate a dense lymphoplasmacytic infiltrate of IgG4-bearing plasmablasts, other lymphocytes, and CD4-positive T cells organized in germinal centers.
- Clinical features
Sentinel organ enlargement with occult additional involvement: most patients present with enlargement or dysfunction of one organ, but multi-organ disease is common, so a search for other involvement is standard.
- Differential diagnosis
Pancreatic or biliary malignancy: presents with a mass and obstructive jaundice, but favors a dilated upstream pancreatic duct with distal atrophy and an elevated CA 19-9, rather than the…
- Diagnosis
No single test is diagnostic; the diagnosis is made by biopsy showing the characteristic histologic triad after alternative diseases are excluded.
- Management
First-line induction is glucocorticoids. Start prednisone 0.6 to 1.0 mg/kg/day orally once daily; systemic disease is maintained at a moderate-to-high dose for about 4 weeks before tapering, and for…
- Complications
Organ fibrosis and failure: unchecked fibrosis converts a reversible mass into irreversible scarring, with biliary strictures, chronic kidney disease, and hypothyroidism from Riedel thyroiditis…
- Prognosis
Generally favorable with treatment: most patients respond to glucocorticoid induction, with a high remission rate for autoimmune pancreatitis (approximately 90%).
- Prevention
No primary prevention exists because no modifiable risk factor for IgG4-RD is established; efforts instead target relapse and treatment complications.
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