Diffuse segmental and pure diffuse global proliferative glomerulonephritis: different patterns of class IV lupus nephritis

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.

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.

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).

LN class IV-S and class IV-G without segmental lesion showed different clinical-histological features and prognosis, suggesting that different mechanisms may exist.