PMC9082185_01
Representative kidney biopsy findings by light and immunofluorescence microscopy. a Glomerulus showing mesangial expansion, double contours, and proliferative nodule formation (periodic acid-Schiff stain, x400, arrows). b-d Immunofluorescence microscopy showing positive linear staining for IgG2 (b, x400) and kappa light chains (c, x200) but no staining for lambda light chains (d, x400) in glomerular and tubular basement membranes.
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F1
Markedly expanded mesangial regions and double contour formation were noted in some area (shown in Fig. 1a). IgG2 (++) (shown in Fig. 1b) and kappa light chains (++) (shown in Fig. 1c) but negative for IgA, IgM, C3, and lambda light chains (shown in Fig. 1d). Immunohistochemistry confirmed that glomeruli and tubules stained intensely for kappa light chains but were negative for lambda light chains.
Representative kidney biopsy findings by electron microscopy. a Powdery electron-dense material depositing in the mesangium and along the tubular basement membranes (arrows) (x6,000). b Microtubules in mesangial regions (arrows) (x6,000). c, d Immunoelectron microscopy showing positive staining for kappa light chains in the mesangium (c) and along the glomerular and tubular basement membranes (c, d, arrows) (x11,500 (c), x20,500 (d)).
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F2
Electron microscopy demonstrated punctate granular electron-dense material deposited in the mesangium and along the glomerular and tubular basement membranes (shown in Fig. 2a). Interestingly, hollow microtubules with a diameter of 35 nm were observed in mesangial regions and the capillary wall at high magnification (shown in Fig. 2b). An immunoelectron microscope confirmed a positive staining for kappa light chains in glomeruli and tubules (shown in Fig. 2c, d) but negative for lambda light chains.