PMC6188736_01
Light microscopy findings. In the renal biopsy specimen, glomeruli showed diffuse double-contours in the glomerular basement membrane and moderate to severe focal endocapillary and mesangial hypercellularity (a). Some nonsclerotic glomeruli were accompanied by fibrocellular crescents (b) ((a), periodic acid methenamine silver stain, original magnification 400x; (b), periodic acid-Schiff stain, original magnification 400x).
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Diffuse segmental double-contours of the glomerular basement membrane and mesangial cell hypercellularity were identified in nonsclerotic glomeruli, exhibiting a membranoproliferative glomerulonephritis-like pattern (Figure 1(a)). Some glomeruli showed moderate-to-severe endocapillary hypercellularity, accompanied by fibrocellular crescents (Figure 1(b)).
Immunofluorescence microscopy findings. Fluorescent immunostaining showed positive staining for IgA and C3, whereas IgG, IgM, and C1q staining were negative. Fluorescent immunostaining of IgA subtypes and light chains showed positive staining for IgA1 and kappa light chains, while staining for IgA2 and lambda light chains was negative.
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Fluorescent immunostaining showed granular staining of IgA and C3, but not of IgG, IgM, or C1q, on glomerular capillaries and some mesangial areas (Figures 2(a)-2(e)). Among the IgA subtypes, staining of IgA1 (GenWay Biotech, San Diego, CA, USA) was observed, but staining of IgA2 (GenWay Biotech) was not identified (Figures 2(f) and 2(g)). With light chain immunostaining, only kappa (SouthernBiotech, Birmingham, AL, USA) was identified and no lambda staining (SouthernBiotech) was seen (Figures 2(h) and 2(i)).
Electron microscopy findings. Electron microscopic examination showed nonorganized deposits in the subendothelial area along the glomerular basement membrane and paramesangial area ((a), original magnification 12,000x; (b), original magnification 50,000x). Because no glomeruli were identified in the portion of the biopsy specimen fixed in glutaraldehyde, the formalin-fixed and paraffin-embedded specimen was reprocessed for electron microscopy. Arrows indicate nonorganized deposits.
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Electron-dense deposits were found in the paramesangium and around the subendothelial space of the glomeruli (Figure 3(a)). No organized structure deposits were identified (Figure 3(b)).