AUTOMATED QUANTIFICATION OF RENAL FIBROSIS WITH SIRIUS RED: IS A ROUTINE METHOD OF THE KIDNEY BIOPSY EVALUATION?

The Aim of our study was to determine the intra- and interobserver variation of the automated quantitative evaluation if cortical interstitial fibrosis performed on kidney biopsy samples stained with Sirius red compared to conventional approaches. Materials and methods. The range of fibrosis was evaluated on 15 renal biopsies obtained from adult patients with minimal change nephropathy, focal segmental glomerulosclerosis and membranous nephropathy. Different methods of fibrosis measurement were used: the automated quantification of Sirius red stained areas with and without polarization, the computerized quantification of the fibrotic interstitium on trichrome-stained samples and the visual assessment offibrotic tissues using quantitative and semiquantitative approaches on trkhrome and PAMS-stained slides. The intra- and interobserver variation of these methods was performed. Results. The quantitative evaluation of interstitial fibrosis with Sirius red stain under both polarized and unpolarized light demonstrated nearly perfect inter- and intraobserver reproducibility (ICC=0,85-0,99). Whereas, visual methods had relatively high variance between observations (ICC=0,48-0,66). Conclusions. The automated quantification of cortical interstitial fibrosis as performed on renal biopsy samples stained with Sirius red has been shown to be a highly accurate approach that could be used as a routine method of the kidney biopsy evaluation.