IgG4-related disease (IgG4-RD) is an immune-mediated, inflammatory condition that can affect multiple organs, marked by lymphoplasmocytic infiltration and IgG4-positive plasma cells. Elevated serum IgG4 is common but not essential. Sole renal manifestation is rare, usually appearing as tubulointerstitial nephritis (TIN) or, less commonly, membranous nephropathy (MN). We present a case of an 87-year-old man with...