Table 2. World Health Organization (WHO) morphologic classification of lupus nephritis (modified in 1982)

Class INormal glomeruli
    a. Nil (by all techniques)
    b. Normal by light microscopy, but deposits by electron or immunofluorescence microscopy
Class IIPure mesangial alterations (mesangiopathy)
    a. Mesangial widening and/or mild hypercellularity (+)
    b. Moderate hypercellularity (++)
Class IIIFocal segmental glomerulonephritis (associated with mild or moderate mesangial alterations)
    a. With “active” necrotizing lesions
    b. With “active” and sclerosing lesions
    c. With sclerosing lesions
Class IVDiffuse glomerulonephritis (severe mesangial, endocapillary or mesangio-capillary proliferation and/or extensive subendothelial deposits)
    a. Without segmental lesions
    b. With “active” necrotizing lesions
    c. With “active” and sclerosing lesions
    d. With sclerosing lesions
Class VDiffuse membranous glomerulonephritis
    a. Pure membranous glomerulonephritis
    b. Associated with lesions of class II
    c. Associated with lesions of class III
    d. Associated with lesions of class IV
Class VIAdvanced sclerosing glomerulonephritis