Background: No consensus has been obtained on the differences between class IV-S and IV-G lupus nephritis (LN), especially regarding renal outcome. Our study investigated clinical-pathological features and prognosis of diffuse segmental and pure diffuse global proliferative LN.
Methods: In this retrospective study, a total of 120 patients with biopsy-proven diffuse LN were included, of which 31 patients were class IV-S and 89 were pure class IVG. Class IV-S was defined as segmental lesion involving ≥ 50% of all glomeruli, while pure class IV-G was defined as global lesion involving ≥ 50% of all glomeruli with no segmental necrosis or crescents. The clinical- pathological and prognostic features of the two classes were compared.
Results: There was no difference in levels of urine protein or serum creatinine between the two groups. Higher serological activity was observed in the pure IV-G group with lower complement C3 (p < 0.001) and C4 level (p < 0.001), compared to the IV-S group. Histologically, immune-complex deposits were significantly more common in the pure IV-G group, with higher prevalence of wire loop (42.7% vs. 0%, p < 0.001) and hyaline thrombi (34.8% vs. 3.2%, p < 0.001). However, the complete remission (CR) rate to intravenous cyclophosphamide (IVCY) induction was lower in the IV-S than in the pure IV-G group (16.7% vs. 53.2%, p = 0.023). After 1 year, the pure class IV-G group had a higher CR rate (71.9% vs. 48.4%, p = 0.017). The 10-year renal survival rate (without doubling of serum creatinine or end-stage renal disease) was significantly lower in patients with IV-S than pure IV-G (75.2% vs. 97.4%, p = 0.028).
Conclusion: LN class IV-S and class IV-G without segmental lesion showed different clinical-histological features and prognosis, suggesting that different mechanisms may exist.