Reproducibility of Fuhrman Nuclear Grading of Renal Cell Carcinoma: A Preliminary Study

Background: The aim of this study was to evaluate intraobserver and interobserver reproducibility of Fuhrman nuclear grading of renal cell carcinoma. Methods: Pathology slides from 46 cases of renal cell carcinoma were rescored by 2 pathologists according to the Fuhrman system. Both intraobserver and interobserver reproducibility were assessed using kappa statistics. Results: The initial Fuhrman grade was grade 1 in 4 of the cases (8.7%), grade 2 in 30 (65.2%), grade 3 in11 (23.9%), and grade 4 in 1 (2.2%). After reviewing the slides by the same pathologist, grades were reassigned as follows: grade 1 in 8 cases (17.4%), grade 2 in 23 (50%), grade 3 in 14 (30.4%), and grade4 in 1 (2.2%). Intraobserver reproducibility of the Fuhrman system was substantial (? = 0.66). Fuhrman grading by the second pathologist was grade 1 in 11 cases (23.9%), grade 2 in 27 (58.7%), grade 3 in 7(15.2%), and grade 4 in 1 (2.2%). Interobserver reproducibility of the Fuhrman system was moderate (? =0.42).Conclusions: Despite substantial intraobserver reproducibility of Fuhrman grading, moderate interobserver reproducibility and low agreement for grade 3 should be a consideration.