Histologically, PSGN is marked by the presence of diffuse glomerular hypercellularity. This hypercellularity is largely due to the proliferation of endothelial and mesangial cells and an influx of inflammatory cells, primarily neutrophils. Under light microscopy, the glomeruli appear enlarged and crowded with cells, disrupting the normal architecture.
Electron microscopy reveals the presence of subepithelial humps, which are deposits of immune complexes made up of antibodies, antigens, and complement components. These humps are a key diagnostic feature of PSGN. Immunofluorescence studies typically show granular deposits of IgG and complement component C3 along the glomerular basement membrane.
