A 40-year-old woman with SLE develops nephrotic-range proteinuria. Renal biopsy shows global hypercellularity with wire-loop thickening of capillary walls and subendothelial deposits on electron microscopy. This is classified as which WHO/ISN class of lupus nephritis?
- A Class II — mesangial proliferative
- B Class IV — diffuse proliferative ✓
- C Class III — focal proliferative
- D Class V — membranous
Correct answer: B. Class IV — diffuse proliferative
Explanation
Class IV diffuse proliferative lupus nephritis is the most severe and most common form, involving more than 50% of glomeruli. Massive subendothelial immune-complex deposits cause thickening of capillary walls, producing the 'wire-loop' appearance on light microscopy. Immunofluorescence shows the 'full house' pattern with IgG, IgA, IgM, C3, and C1q positivity. It carries the worst prognosis among lupus nephritis classes.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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