A 32-year-old woman with SLE presents with nephrotic range proteinuria (4.5 g/day), hematuria, and hypertension. Renal biopsy shows diffuse endocapillary proliferation, wire-loop lesions, and subendothelial immune deposits (IgG, IgM, C3, C1q — full house). The ISN/RPS classification of this nephritis is:
- A Class III (focal proliferative lupus nephritis)
- B Class V (membranous lupus nephritis)
- C Class IV (diffuse proliferative lupus nephritis) ✓
- D Class II (mesangial proliferative)
Explanation
Class IV diffuse proliferative lupus nephritis (ISN/RPS 2003 classification, revised 2018) involves >50% of glomeruli with endocapillary or extracapillary proliferation, subendothelial immune deposits, and wire-loop lesions (large subendothelial deposits bulging into the capillary lumen). Full-house immunofluorescence (IgG, IgM, IgA, C3, C1q) is characteristic of lupus nephritis. Class IV carries the worst renal prognosis and requires aggressive immunosuppression with cyclophosphamide or mycophenolate mofetil plus corticosteroids (ELNT/EURO-Lupus regimens). Class III involves <50% of glomeruli; Class V shows subepithelial deposits (membranous pattern).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.