A 30-year-old woman with SLE develops nephrotic syndrome. Renal biopsy reveals diffuse thickening of glomerular basement membranes with 'wire-loop' deposits. IF shows granular IgG and C3 in subendothelial and mesangial locations. This corresponds to which WHO/ISN class of lupus nephritis?

• A Class IV (Diffuse lupus nephritis) ✓
• B Class III (Focal lupus nephritis)
• C Class V (Membranous lupus nephritis)
• D Class VI (Advanced sclerosing lupus nephritis)

Explanation

Class IV (diffuse) lupus nephritis is the most severe form and is characterized by 'wire-loop' lesions — massive subendothelial immune complex deposits that create a refractile thickening of the GBM on LM. IF shows a 'full house' granular pattern with IgG, IgA, IgM, C1q, C3. Class V (membranous LN) features subepithelial deposits without wire loops. Wire loops in class IV reflect the high complement-activating immune complex burden.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.