IgG4 RD
A heterogenous group of syndromes linked by lymphoplasmacytic, infiltrative disease featuring IgG4-positive plasma cells, tumor-like growths, and fibrosis are collectively termed IgG4-RD. RPF and isolated aortitis are increasingly linked to this group of disorders. The abdominal aorta is most commonly involved, although thoracic aortic lesions have also been reported. The pathogenesis of these diseases is not well understood; however, they appear to have both allergic and autoimmune features. Elevated IgG subclass 4 antibodies are a unifying feature (but not pathogenic) in this disease. Other organ involvement includes type I autoimmune pancreatitis (the most common IgG4-RD manifestation), sclerosing cholangitis, salivary and lymph node involvement, orbital pseudotumor, pneumonitis, nephritis, central nervous system, and thyroiditis. Classification criteria for IgG4-RD are in development.
