A 28-year-old woman with SLE has a serum creatinine of 1.8 mg/dL, proteinuria 3.2 g/day, and active urinary sediment (RBC casts). Renal biopsy shows diffuse mesangial and subendothelial immune deposits with wire-loop lesions. ISN/RPS classification of lupus nephritis in this case is:

• A Class III (focal lupus nephritis)
• B Class IV (diffuse lupus nephritis) ✓
• C Class V (membranous lupus nephritis)
• D Class II (mesangial proliferative lupus nephritis)

Explanation

ISN/RPS Class IV (diffuse lupus nephritis) is defined by involvement of >50% of glomeruli with endocapillary or mesangial proliferation and subendothelial immune deposits. Wire-loop lesions (massive subendothelial deposits distorting the glomerular capillary wall) are characteristic of class IV. Class III affects <50% glomeruli. Class V shows subepithelial deposits (membranous pattern). Class II shows only mesangial changes. Class IV carries the worst prognosis and requires aggressive immunosuppression.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.