Digital Pathology Grading of Renal Cell Carcinoma Is Non-Inferior to Glass Slides, With Potential for Improved Interobserver Agreement
Three uropathologists graded 60 renal cell carcinomas using the WHO/ISUP system on both digital and glass slides across repeated sessions. Intraobserver concordance between digital and glass was 65-78%, with kappa scores comparable to glass-glass reproducibility and no systematic tendency to upgrade or downgrade on digital. Interobserver agreement was slightly higher on digital pathology (kappa 0.58) than on glass (kappa 0.45), suggesting digital reporting may improve grading consistency.
The original study
WHO/ISUP grading of clear cell renal cell carcinoma and papillary renal cell carcinoma; validation of grading on the digital pathology platform and perspectives on reproducibility of grade.
- Authors
- Browning L, Colling R, Verrill C
- Journal
- Diagnostic pathology
- Type
- Journal Article, Validation Study
- PMID
- 34419085
Original abstract
BACKGROUND: There are recognised potential pitfalls in digital diagnosis in urological pathology, including the grading of dysplasia. The World Health Organisation/International Society of Urological Pathology (WHO/ISUP) grading system for renal cell carcinoma (RCC) is prognostically important in clear cell RCC (CCRCC) and papillary RCC (PRCC), and is included in risk stratification scores for CCRCC, thus impacting on patient management. To date there are no systematic studies examining the concordance of WHO/ISUP grading between digital pathology (DP) and glass slide (GS) images. We present a validation study examining intraobserver agreement in WHO/ISUP grade of CCRCC and PRCC. METHODS: Fifty CCRCCs and 10 PRCCs were graded (WHO/ISUP system) by three specialist uropathologists on three separate occasions (DP once then two GS assessments; GS1 and GS2) separated by wash-out periods of at least two-weeks. The grade was recorded for each assessment, and compared using Cohen's and Fleiss's kappa. RESULTS: There was 65 to 78% concordance of WHO/ISUP grading on DP and GS1. Furthermore, for the individual pathologists, the comparative kappa scores for DP versus GS1, and GS1 versus GS2, were 0.70 and 0.70, 0.57 and 0.73, and 0.71 and 0.74, and with no apparent tendency to upgrade or downgrade on DP versus GS. The interobserver kappa agreement was less, at 0.58 on DP and 0.45 on GS. CONCLUSION: Our results demonstrate that the assessment of WHO/ISUP grade on DP is noninferior to that on GS. There is an apparent slight improvement in agreement between pathologists on RCC grade when assessed on DP, which may warrant further study.