A 28-year-old woman with a 3-year history of systemic lupus erythematosus presents to the nephrology clinic for evaluation of progressive renal disease. She reports new-onset bilateral lower extremity edema and foamy urine. Vital signs are BP 148/92 mmHg, HR 86 bpm, RR 16, temp 37.0°C, SpO2 99% on room air. Laboratory studies show serum creatinine 0.9 mg/dL, serum albumin 2.2 g/dL, and 24-hour urine protein 5.8 g. Serum complement levels are depressed (C3 22 mg/dL, C4 8 mg/dL). Urinalysis reveals 3+ protein and occasional RBCs with no casts. Kidney biopsy shows a mixture of basement membrane thickening with spike-and-dome lesions alongside proliferation of glomerular endocapillary cells with numerous subendothelial immune complexes. Which WHO/ISN-RPS classification of lupus nephritis is most consistent with these findings?

1. A)Class II (mesangial proliferative lupus nephritis)
2. B)Class III (focal proliferative lupus nephritis)
3. C)Class IV (diffuse proliferative lupus nephritis)
4. D)Class V (membranous lupus nephritis)
5. E)Class IV-S (diffuse proliferative with superimposed membranous features)GABARITO