Overview of the Immunoglobulin G4-related Disease Spectrum

Immunoglobulin G4 (IgG4)-related disease is a newly named fibroinflammatory condition characterized by tumefactive lesions that contain dense lymphoplasmacytic infiltrates rich in IgG4-positive cells.Elevated serum IgG4 concentrations also often accompany IgG4-related disease.Many medical conditions that were long viewed as diseases confined to single organs (e.g., Mikulicz disease, type 1 autoimmune pancreatitis, Riedel's thyroiditis, multifocal fibrosclerosis, inflammatory pseudotumor, mediastinal fibrosis, retroperitoneal fibrosis, and etc.) are now designated as part of the spectrum of IgG4-related disease.The preferred nomenclature suggested by a committee of international experts uses the prefix "IgG4-related-" for individual organ involvement, regardless of the organ system affected.One exception is type 1 autoimmune pancreatitis (IgG4-related pancreatitis).Comprehensive diagnostic criteria for IgG4-related disease and organ-specific diagnostic criteria (e.g., IgG4related dacryoadenitis and sialadenitis, type 1 autoimmune pancreatitis, IgG4-related kidney disease and IgG4-related sclerosing cholangitis) can aid clinicians in the diagnosis of this erratic condition.