IgG4-related kidney disease

IgG4-related disease (IgG4-RD) is a recently recognized systemic immune-mediated disease that can affect nearly any organ or tissue. The most common manifestation in the kidney is IgG4-related tubulointerstitial nephritis (IgG4-TIN), which can present as renal insufficiency, renal mass lesions, or both. Histologically, IgG4-TIN is a plasma cell-rich interstitial inflammatory infiltrate with mononuclear cells, eosinophils, and increased IgG4+ plasma cells, along with expansile interstitial fibrosis that often has a " storiform" appearance. Tubular basement membrane immune complex deposits, best visualized on immunofluorescence staining, are present in most cases. IgG4-TIN usually shows a rapid response to steroid therapy. Glomeruli may be affected by IgG4-RD, usually in the form of membranous glomerulonephritis; other glomerular lesions have also been described. This review describes the different histopathologic patterns of renal involvement by IgG4-RD, with associated clinical, radiographic, and serologic features.