The INS/RPS classification of LN pointed out more a qualitative(segmental-global) than quantitative(</>50%) factors.A RB could be usefull for a better clinical-pathological understanding of LN. The aim of the present international multi-centric study was to give a validation of ISN/RPS classification and the predictive value of RB.
This multi-centric retrospective study included 142 patients with histological diagnosis of LN. Proteinuria, creatinine and blood pressure at the time of the first biopsy(FB) and RB were available. All the histological diagnoses (FB and RB) were centrally reviewed .
At FB 12.7% cases were histologically classified as Class II, 10.6% Class III, 4.9% Class IV-S, 40.9% Class IV-G , 16.9% . At FB, severe mesangial proliferation was present in 26,67% class III , 35.7% class IV-S 94.8% class IV-G (p<.001). Tuft necrosis was present in 13,3% class III , 42.8% class IV-S and 6.8% class IV-G (p<.005). Wire loops were absent in class III , 14.29% class IV-S and 75.86% class IV-G (p<.001).Similar differences were present at RB. The correlation between clinical variables and histological classes at FB and RB demostrated a much severe renal symptoms in class IV-G at FB and RB.
The correlation between ISN/RPS classification at FB and RB is reported in Tab 1. The data demonstrated that the transformation among segmental (III-IV-S) and “mesangial” forms (II-IV-G) was extremely rare. The correlations between different classes and clinical parameters at the final follow-up from FB and RB suggest that classes correlate modestly with clinical evolution at FB but strongly at RB
Data suggest that clear morphological differences between segmental and global forms are possible expression of different pathogenetic mechanisms with also definite clinical differences and do not represent a simple continuum of disease.
RB, in a large cohort of patients provide more predictive informations relevant to long term renal outcome than baseline biopsy.