IgG4-Related Tubulointerstitial Kidney Disease

Abstract

IgG4-related disease (IgG4-RD) is a systemic immune-mediated disease that can involve nearly any organ, including the kidney. The kidneys are involved in approximately 15–25% of cases of IgG4-RD. Kidney involvement most commonly takes the form of tubulointerstitial nephritis (IgG4-TIN), which can present as kidney failure, mass forming lesions by radiographic studies, or both. Less commonly, membranous glomerulonephritis occurs in association with IgG4-RD, and these patients present with proteinuria. Histologically, IgG4-TIN is a plasma cell rich tubulointerstitial nephritis with increased IgG4-positive plasma cells usually accompanied by a peculiar expansile, or “storiform”, fibrosis. Most (>80%) cases of IgG4-TIN also show tubular basement membrane immune complex deposits by immunofluorescence or electron microscopy; this finding is useful for diagnosis. Ultimately, a diagnosis of IgG4-RD associated kidney involvement relies on clinical, laboratory, imaging, and histological findings. IgG4-TIN, similar to other organ manifestations of IgG4-RD, typically shows a brisk response to immunosuppressive therapy. Recent studies have helped elucidate the nature of this disease, although many aspects of pathogenesis are unknown.