Table 1. Histopathological classification of postinfectious glomerulonephritis.

	Acute PIGN	Persistent PIGN	Healed PIGN
Light microscopy(H&E, PAS, Masson’s trichromeand PAS -Metheniminesilver stained slides)	• Diffuse, moderate tomarked, segmental to globalendocapillary hypercellularity(mostly neutrophilic)	• Focal, mild to moderate,segmentalendocapillaryhypercellularity(mostly mononuclear)	• Focal, absent to mild segmental endocapillary hypercellularity (mostly mononuclear)
	• ± Moderate tomarked mesangial hypercellularity	• ± Mild to markedmesangial hypercellularity	• ± Absent to moderate mesangial hypercellularity
Immunofluorescence	• Granular capillarywall (GBM), with ±mesangial IgG and/or C3deposits	• Variable granularmesangial C3± IgGwith ± capillary wall(GBM) deposits	• Variable granular mesangial C3± IgG with ± capillary wall (GBM) deposits
	• Mesangial IgA in IgA-dominant PIGN	• ± IgA, IgM, C1q,kappa or lambda	• ± IgA, IgM, C1q, kappa or lambda
	• ± IgA, IgM, C1q, Kappaor lambda
Electron microscopy	• Numerous irregularly-spacedsubepithelial electrondense deposits, frequently inmesangial “notch”,rare “humps”, undergoingminimal to mild resorption	• Occasional to numeroussubepithelial electrondense deposits,a few “humps”, a few(at least 1) in mesangial“notch”, undergoingvariable (mild to marked)resorption	• Few subepithelial electron dense deposits, rare “humps” (up to 2), a few in mesangial “notch”, undergoing moderate to marked resorption
	• ±Rare intramembranous,mesangial, subendothelial	• ± Variable numbersof subendothelial,intramembranous, mesangial	• Numerous subendothelial, intramembranous, mesangial, undergoing moderate to marked resorption

Adapted from Haas, M., Hum Pathol, 2003. 34(1): p. 3–10.