IgG4-related kidney disease: a rare cause of tubulointerstitial nephritis

A 42-year-old black female was referred with unexplained renal failure. Initial radiological examination revealed a right adnexal inflammatory mass and bilateral hydronephrosis. The renal failure persisted despite the insertion of double J stents. A kidney biopsy showed a lymphoplasmacytic interstitial infiltrate that stained positive for IgG4. A diagnosis of IgG4-related tubulointerstitial nephritis (TIN) with pelvic-limited retroperitoneal fibrosis (RPF) was made and immunosuppressive treatment was initiated, with a good initial response to therapy. This report highlights the importance of considering RPF in cases of unexplained obstructive uropathy and of considering the diagnosis of IgG4-related disease when TIN is found in combination with other organ involvement.