A 32-year-old woman with SLE on hydroxychloroquine and prednisolone presents with worsening proteinuria (3.5 g/day) and an active urinary sediment with RBC casts. Renal biopsy shows diffuse proliferative nephritis with subendothelial and mesangial immune deposits. Which ISN/RPS class is this?
- A Class III
- B Class IV ✓
- C Class V
- D Class II
Correct answer: B. Class IV
Explanation
ISN/RPS Class IV (diffuse lupus nephritis) is characterised by diffuse glomerular involvement (>50% of glomeruli) with subendothelial immune complex deposits and is associated with the most severe clinical presentation including heavy proteinuria, haematuria, RBC casts, and hypertension. Class III affects <50% of glomeruli (focal); Class V is membranous (predominant subepithelial deposits) typically without RBC casts; Class II is mesangial only with mild proteinuria.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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