Glomerular basement membrane duplication 2025-10-26T15:43:13Z GBM duplication Glomerular basement membrane duplication (GBM-DP) is often found in diabetic neprhopathy and is a pathological feature that suggests endothelial injury. See Figure 1 of PMID:30467801. Membranoproliferative glomerulonephritis (MPGN) is a pattern of pathological injury characterized by thickening of or double contour formation on the glomerular basement membrane (GBM) (membrano-) with mesangial and/or endocapillary proliferation (proliferative). When injury persists, new basement membranes can form underneath the damaged endothelium, leading to the characteristic tram track appearance by silver staining. Tram-track appearance of GBM Glomerular basement membrane duplication (GBM-DP) can be seen with Periodic acid-Schiff and silver stains. This appearance results from the presence of subendothelial deposits and the so-called mesangial interposition whereby mesangial cells, infiltrating mononuclear cells, or even portions of endothelial cells interpose themselves between the endothelium and basement membrane, with new, inner GBM-like material being laid down. This produces a double contour or tram-track appearance on light or electron microscopy. This finding often reflects splitting of the lamina densa and is associated with disease processes such as membranoproliferative glomerulonephritis, transplant glomerulopathy, and diabetic nephropathy. Double contour of glomerular basement membrane GBM reduplication Abnormal glomerular basement membrane morphology