IgG4-Related Kidney Disease: A Curious Case of Interstitial Nephritis with Hypocomplementemia

Abstract

IgG4-related kidney disease has been relatively newly recognized over the last two decades as a combination of an autoimmune and allergic disorder, with elevated serum IgG4 level and hypocomplementemia among its characteristic features. Here we report the case of a man with interstitial nephritis presenting with acute kidney injury and hypocomplementemia but normal serum IgG4 level and provide a literature review of IgG4-related kidney disease. This case highlights the importance of IgG4-related kidney disease as an important differential diagnosis in any patient presenting with a clinical syndrome mimicking acute interstitial nephritis with hypocomplementemia. A high index of suspicion with a low threshold for performing a native kidney biopsy would be paramount as patients do respond well to corticosteroid therapy.

Keywords: Acute interstitial nephritis; Acute kidney injury; Hypocomplementemia; IgG4-related kidney disease; Tubulointerstitial disease.

Fig. 1

a IgG4-positive plasma cells (arrow) on immunohistochemistry (×400). b Extensive inflammation composed predominantly of mononuclear cells including prominent plasma cells admixed with scattered neutrophils and eosinophils (periodic acid-Schiff, ×400). c Storiform pattern of interstitial fibrosis (Masson trichrome, ×100). d Zonal character of tubulointerstitial inflammation with relative un-involvement of another zone (e) (periodic acid-Schiff, ×100).

Fig. 2

Trend of creatinine.