IgG4-related kidney disease (IgG4-RKD) is a recently recognized entity associated with IgG4-related disease (IgG4-RD). IgG4-RD is a systemic disorder with multiple organ involvement, firstly identified in pancreas. IgG4-RKD is mainly in the form of tubulointerstitial nephritis characterized by predominant IgG4-positive plasma cell infiltrate and fibrosis in storiform (cartwheel-like) pattern. Immune complex deposits detected by immunofluorescence method is a useful diagnostic feature. Membranous nephropathy has been described in IgG4-RKD, but unclear if it shares similar etiology with the tubulointerstitial disease.
The diagnosis of IgG4-RKD usually requires histology though clinical, laboratory and radiologic findings are helpful and leading to biopsy.
Review in Saeki et al.
