In systemic lupus erythematosus (SLE), the wire-loop lesion on light microscopy of renal biopsy corresponds to which WHO/ISN-RPS class of lupus nephritis?

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

Explanation

Wire-loop lesions are seen in Class IV (diffuse proliferative) lupus nephritis — the most severe form — representing massive subendothelial immune complex deposits that thicken glomerular capillary walls, making them appear rigid and hyaline-like (resembling wire loops) on PAS stain. IF shows full house pattern (IgG, IgM, IgA, C3, C1q). Class V (membranous LN) shows subepithelial deposits and spike pattern. Class II shows mesangial expansion without endocapillary proliferation.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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