The impact of the ISN/RPS classification of glomerulonephritis in systemic lupus erythematosus on the histological diagnosis of focal and diffuse lupus nephritis

Different frequencies for each class of LN have been reported when the biopsies were classified according to WHO and ISN/RPS classification systems.The purpose of this study was to investigate the reason for the observed differences in frequencies of LN, when the biopsies are classified under different classifications. The inclusion of sclerotic glomeruli in the count of total glomeruli affected by LN, in the ISN/RPS 2003 classification, might be a possible reason for the differences in diagnoses. We reclassified 172 renal biopsies with LN class III and IV using two different classification systems.Our results indicate the importance of the change in handling the sclerotic glomeruli, which resulted in class-switching in some of the cases. This is important because depending on the approach of the clinician, it may lead to an increased immunosuppression for the same lesion when diagnosed under the ISN/RPS classification compared to the 1995 WHO classification system.