PMC6465718_01
LM findings of renal biopsy specimens. a Glomerular global sclerosis and focal tubular atrophy with interstitial fibrosis and cellular infiltration (PAS stain, x200). b Lobular accentuation with segmental nodular formation in the glomerulus (PAS stain, x200). c Mesangial enlargement and thickening capillary walls showing double contour (arrowheads) (PASM stain, x400). d-h IF findings. Extensive granular deposits of IgG, C3 and Ciq in the glomerular mesangial areas and along the glomerular capillary walls (x200).
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F1
Three glomeruli were globally sclerosed and focal tubular atrophy with interstitial fibrosis and inflammatory cell infiltration were observed around them (Fig. 1a). Lobular accentuation with segmental nodular formation due to an increase in cells and matrix were also observed (Fig. 1b). The majority of glomerular capillary loops showed double contours (Fig. 1c). IgG, C3 and C1q were strongly positive in the granular deposits along the glomerular capillary walls and mesangial areas (Fig. 1d, g, h). IgA, IgM and fibrinogen revealed weak or negative signals (Fig. 1e, f). In electron microscopy, foot processes of glomerular epithelial cells were effaced (Fig. 2a).
Electron microscopy findings. a Part of a glomerulus showing epithelial foot process effacement, subendothelial, subepithelial and paramesanial EDDs. EDDs in the glomerular basement membrane (GBM) are observed (x4,600). b Massive EDDs in subendothelial, subepithelial and GBM. Hump-like subepithelial deposits are observed (x6,400). c A magnified glomerular capillary loop in Figure 3a. A large amount of EDDs in the subendothelial area (x6,400). d Unorganized and granular structure of EDDs (x10,000).
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F2
IgA, IgM and fibrinogen revealed weak or negative signals (Fig. 1e, f). In electron microscopy, foot processes of glomerular epithelial cells were effaced (Fig. 2a). Massive electron-dense deposits (EDDs) were observed in the glomerular mesangial areas, basement membranes, subendothelial areas and subepithelial areas (Fig. 2b). No inflammatory cells were observed in the glomerular capillary loops (Fig. 2c). The EDDs exhibited immune complex-like granular structures (Fig. 2d).
a, b IF for IgG subclasses. Granular IgG1 and IgG2 deposits are observed in the glomerular mesangial areas and along the glomerular capillary walls (x200). c, d Immunohistochemistry for kappa (c) and lambda (d) light chain. Positive staining for both kappa and lambda light chains in the glomerular mesangial areas and along the glomerular capillary walls (x200).
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F3
IgG deposits (PGNMID). Immunofluorescence for anti-IgG1 and IgG2 antibodies were positive in both the glomerular capillary loops and the mesangial areas (Fig. 3a, b). IgG4 antibodies was negative (data not shown). Immunohistochemistry revealed that the IgG deposited within the glomeruli were both kappa and lambda positive, suggesting that polymeric IgG was deposited in the glomeruli (Fig. 3c, d).