PMC6745099_01
Renal biopsy pathology. Up to fourteen glomeruli were identified under light microscopy, and analysis found glomeruli with diffuse thickening of capillary membranes (a, b). There was mild mesangial matrix expansion and hypercellularity (c, d). There was no evidence of glomerular sclerosis. Segmental duplication of capillary walls with accumulation of eosinophilic deposits was noted between the duplicated membranes. Silver stain reveals thickened capillary walls, duplication of basement membranes with eosinophilic deposits in between (e, f). Trichrome stain showed mild to moderate focal interstitial fibrosis associated with tubular atrophy and drop out with scattered lymphocytes within the fibrotic interstitium. No acute tubulitis was seen. Electron microscopy found diffuse effacement of podocyte foot processes and prominent thickening of capillary loops by a combination of subendothelial deposits, basement membrane duplication, and mesangial cell interposition. On immunofluorescence, there was a diffuse 2 to 3+ mesangial reaction and segmental capillary loop reaction for IgA, IgM, C3, kappa, and lambda (g). The reaction for IgG was only 1+, and there was no reaction for C1q or fibrin. Pronase-retrieval IgG stain on paraffin-embedded tissue was negative. The results indicated a diagnosis of IgA predominant nephropathy.
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fig1
Microscopic analysis resulted in a diagnosis of IgA predominant nephropathy (Figure 1).