PMC6001933_01
(A-D) Glomeruli with increased volume, lobulated aspect, endocapillary hypercellularity with reduced capillary lumen and increased mesangial matrix. In addition, there are double contours in some capillary loops. (A) Hematoxylin eosin; (B) Sirius Red; (C) Periodic acid silver methenamine stain (PAMS); (D) Masson Trichrome - magnification: 20x. (E) Immunofluorescence for immunoglobulin G showing accentuated deposition in capillary loops, subendothelial glomerulus. (F and G) Enlargement of subendothelial space with randomly distributed fibrils and mesangial interposition (transmission electron microscopy: F - 7000x; G - 12,000x) and (H) detail of the deposit of fibrillary material (transmission electron microscopy: 30,000x).
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A renal biopsy revealed a membranoproliferative pattern at light microscopy (Figure 1A-D) and an investigation of beta-fibrillose by Congo red staining was negative. Subendothelial deposits of IgG (Figure 1E), Kappa, Lambda, C3 and C1q were identified in glomeruli by immunofluorescence. Electron microscopy showed mesangial and subendothelial fibrillary deposits (Figure 1F-H).