Evaluation of Renal Interstitial Fibrosis by Trichrome Staining, Immunohistochemical and Morphometrical Analysis, and Its Correlation with Renal Dysfunction

Abstract Background: Renal interstitial fibrosis is outcome measure of increasing importance in transplantation and native diseases, and accurate assessment is essential for various scoring systems. There is limited research on the merits of fibrosis measurement methods. Aim: This study aimed to quantify and compare the degree of renal fibrosis by using visual analysis and computerized morphometry using trichrome staining and anti-collagen III immunohistochemistry and correlate with renal dysfunction. Materials and Methods: Fifty biopsy samples of various native renal diseases with a wide range of fibrosis were included in the study. Fresh sections were cut and stained with anti-collagen III antibody. Masson’s trichrome- and anti-collagen III-stained slides were subjected to visual assessment by two pathologists following standardized criteria. Digital images were evaluated by computerized morphometry using ImageJ software. Renal cortical fibrosis was expressed as a percentage of the total analyzed cortical tubulointerstitial region. Results: The percentage of interstitial fibrosis obtained by each method was compared with each other and with the estimated glomerular filtration rate (eGFR). The interobserver agreement was good for visual assessment using Masson’s trichome staining and excellent for visual assessment using anti-collagen III. The results of visual assessment using anti-collagen III correlated well with those of computerized morphometric assessment. Morphometric analysis of Masson trichrome-stained slides was difficult, and digital images could not be segmented satisfactorily. Computerized morphometric and visual analysis of anti-collagen III immunohistochemistry are good predictors of the eGFR. Conclusions: Anti-collagen III immunostaining is a very useful tool for accurate measurement of renal interstitial fibrosis. Morphometry is a useful adjunct for assessment of renal interstitial fibrosis.