PMC8273166_01
Patient renal biopsy findings. (A) Light microscopy showed minor shrinkage of glomerular capillary wall with dense interstitial lymphoplasmacytic cell infiltrates and variable degree of interstitial fibrosis (periodic methenamine silver and Masson trichrome staining, x40). (B) Almost normal glomeruli (periodic methenamine silver and Masson trichrome staining, x400). (C,D) "Storiform" fibrosis with tubular atrophy in the tubulointerstitium (periodic methenamine silver and Masson trichrome staining, x200). (E) Immunofluorescence staining showed IgG granular staining along TBM and interstitium (x400). (F) Immunofluorescence staining showed lambda linear staining along TBM (x400). (G) Electronic dense deposits along tubular basement membrane (x12,000). (H) Electronic dense deposits in the mesangium (x12,000). (I-L) Immunohistochemical staining of IgG subclass (IgG1-IgG4) (x200).
fmed-08-684889-g0001.jpg
PMC8273166_01_fmed-08-684889-g0001.jpg
F1
There were profound interstitial infiltration with lymphocytes, plasma cells, and a few eosinophils. "Storiform" fibrosis with tubular atrophy can be seen in the tubulointerstitium (Figures 1A-C). Immunofluorescence microscopy revealed one out of seven glomeruli with crescent and granular mesangial staining for IgG and C3, and granular staining for IgG, kappa, lambda, IgG1, IgG2, IgG3, IgG4, and C1q along TBM and interstitium and linear staining for lambda also along TBM (Figure 1D). Electron microscopy revealed one glomerulus with numerous electronic dense deposits along tubular basement membrane with focal mesangial deposits (Figure 1E). Immunohistochemistry revealed that IgG1-positive plasma cells were 35-45/HPF, IgG2-positive plasma cells 40-50/HPF, IgG3-positive plasma cells 90-100/HPF, and IgG4-positive plasma cells 10-15/HP (Figures 1F-I).