Lupus nephritis and kidney transplantation: A narrative review of patient and graft outcomes

Table 1 International Society of Nephrology/Renal Pathology Society Classification of Lupus Nephritis (2018 revision) and its clinical implications

Class	Key histological features	2018 revision updates	Clinical implications
Class I	Minimal mesangial LN; immune complex deposition confined to mesangium	Emphasis on subtle mesangial deposits	Usually asymptomatic; normal urinalysis; excellent prognosis
Class II	Mesangial proliferative LN; mesangial hypercellularity and matrix expansion	Clarified distinction between mesangial hypercellularity vs deposits only	Mild disease; hematuria/proteinuria; generally favorable outcomes
Class III	Focal LN; < 50% of glomeruli affected with segmental/global endocapillary or extracapillary proliferation	Activity/chronicity indices introduced; segmental vs global lesions highlighted	Variable course; risk of progression; requires immunosuppression
Class IV	Diffuse LN; ≥ 50% of glomeruli affected; extensive endocapillary/extracapillary proliferation	Activity/chronicity scoring; segmental vs global lesions emphasized	Most severe and common form; high risk of renal failure; aggressive therapy needed
Class V	Membranous LN; diffuse thickening of glomerular capillary walls due to subepithelial deposits	Recognition of mixed class V + III/IV lesions	Presents with nephrotic syndrome; risk of progression if mixed lesions present
Class VI	Advanced sclerosing LN; ≥ 90% of glomeruli globally sclerosed	Highlighted as irreversible stage	Poor prognosis; progression to ESKD; supportive care or renal replacement therapy

LN: Lupus nephritis; ESKD: End-stage kidney disease.