PMC10286732_01
Microscopic analysis of the kidney biopsy specimen. a, b: Light microscopy showed partial thickening of the glomerular basement membrane (GBM) and a partial increase in the area of mesangial matrix. a: Periodic acid-Schiff staining; original magnification x 200; b: Periodic acid methenamine silver staining; original magnification x 200; c: Immunofluorescence microscopy showed mesangial dotted (large arrow) and peripheral linear (small arrow) staining for C3. Original magnification x 200; d: C4d staining showed positive findings in only a few glomeruli. Original magnification x 200. e - k: Electron microscopy. e: Weakly magnified images showing deposits (white arrow). Original magnification x 1,500; f: Strongly magnified images of square A of Figure 1d showing two types of deposits in the mesangial area: electron-dense deposits (large arrow) and moderately electron-dense deposits (small arrow). Original magnification x 9,000; g - i: Strongly magnified images of square B of Figure 1d showing deposits in the GBM near the paramesangium; deposits had a linear electron-dense structure (large arrow) on the endothelial side and were a moderately electron-dense structure (small arrow) on the epithelial side. g: Original magnification x 4,500; h: Original magnification x 9,000; i: original magnification x 18,000; j - k: Strongly magnified images of square C of Figure 1d showing deposits in the distal portion of the GBM consisting of linear and evenly distributed electron-dense deposits (large arrow) on the endothelial side and hump-shaped moderately electron-dense deposits (small arrow) on the epithelial side. j: Original magnification x 4,500; k: Original magnification x 9,000; l - p: Immunoelectron microscopy; l: Deposits in the mesangial area: Gold particle-labeled C3 was seen (black dots). Original magnification x 10,000; m: Deposits in the GBM near the paramesangium: Gold particle-labeled C3 was noted throughout the thickened GBM but was not present in normal GBM (small arrow). Original magnification x 5,000; n: Deposits in thickened GBM: Gold particle-labeled C3 was noted throughout the thickened GBM (arrow). Original magnification x 5,000; o: Irregularly thickened GBM: Gold particle-labeled C3 was noted throughout the thickened GBM (arrow). Original magnification x 10,000; p. Thickened and non-thickened GBM; Gold particle-labeled C3 was noted throughout the thickened GBM (large arrow) but was not present in normal-range GBM (small arrow). Original magnification x 5,000.
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Figure1
Partial thickening of the GBM and a partial increase in the area of the mesangial matrix were also noted (Figure 1a, b). C3 (Figure 1c), but staining was negative for IgG, IgA, IgM, C4, and C1q. C4d staining showed positive findings in only a few parts of glomeruli (Figure 1d), although staining was not as strong as for C3.  On electron microscopy, electron-dense deposits were seen mainly in the mesangial area, the GBM near the paramesangium, and the distal portion of the GBM (Figure 1e). In the mesangial area, both electron-dense and moderately electron-dense deposits were seen (Figure 1f). Deposits in the GBM near the paramesangium consisted of linear electron-dense structures on the endothelial side and moderately electron-dense deposits on the epithelial side (Figures 1g, h, i). Deposits in the distal portion of the GBM consisted of linear electron-dense deposits on the endothelial side and hump-shaped, moderately electron-dense deposits on the epithelial side (Figures 1j, k).  Immunoelectron microscopy performed according to a previously published method showed that gold particle-labeled C3 was localized in the electron-dense and moderately electron-dense deposits seen on electron microscopy; however, it was not present in non-thickened GBM (Figures 1l, m, n, o, p).
Clinical course.
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Figure2
Renal function remained unchanged (Figure 2).