Renal involvement by IgG4-related disease

IgG4-related disease (IgG4-RD) is a recently recognized systemic immune-mediated disease, typically characterized by mass-forming fibroinflammatory lesions that may affect nearly any organ. In the kidney, IgG4-RD is most often manifested as IgG4-related tubulointerstitial nephritis (IgG4-TIN), which can present as mass lesions, renal insufficiency, or both. IgG4-TIN has a histologic appearance to other organs involved by IgG4-RD and shows a plasma cell-rich tubulointerstitial nephritis with storiform fibrosis; most cases also show tubular basement membrane immune complex deposits, which is a helpful feature on biopsy. IgG4-TIN, like fibroinflammatory manifestations of IgG4-RD in other organs, typically shows a brisk response to steroid therapy, although there is a high relapse rate. Glomerular involvement by IgG4-RD, especially membranous glomerulonephritis, has been recognized more recently.