IgG4-related tubulointerstitial nephritis:a clinicopathologic analysis and review of the literature

LI Li; ZHANG Yi-fen; SHEN Long-shu; ZHU Chang-le; WU Jin-rong

doi:10.3969/j.issn.1007-8096.2023.09.008

Abstract：Objective To investigate the clinicopathological features of IgG4-related tubulointerstitial nephritis(IgG4-TIN).Methods The morphology and immunoprofiles of the IgG4-TIN were confirmed by pathology,and the relevant literatures were reviewed.Results Two cases were middle-aged and elderly patients,with elevated serum creatinine and IgG4 levels.H&E staining showed a large number of lymphocytes and plasma cells infiltration in the interstitium,multifocal and lamellar fibrosis with storiform and"bird's eye"changes.The wall of small vessels was thickened.Immunofluorescence microscopy showed IgG and IgG4 deposited along the tubular basement membrane.Immunohistochemically,infiltrating plasma cells diffusely expressed CD138 and CD38.There were more than 100/HPF IgG4-positive plasma cells at the hot spots,and the ratio of IgG4-positive/IgG-positive plasma cells was over 40％.IgG and PLA2R(phospholipase A2 receptor)were concomitant positive along the glomerular capillary walls on immunofluorescence microscopy,and electron microscopy showed a large amount of electron dense deposits in the subepithelial and basement membrane of glomerular capillary loops.This case was associated with PLA2R-positive membranous nephropathy.Conclusion IgG4-TIN is a rare disease and may be complicated with membranous nephropathy and other glomerulopathy.It can be diagnosed according to the serum IgG4 level,typical histopathological characteristics and immunophenotype.Glucocorticoid is still the fist choice for treatment of IgG4-TIN.