Validation of grading of non-invasive urothelial carcinoma by digital pathology for routine diagnosis

Hayleigh Colling,Lisa Browning,Richard Colling,Clare Verrill

doi:10.1186/s12885-021-08698-4

Abstract

BackgroundPathological grading of non-invasive urothelial carcinoma has a direct impact upon management. This study evaluates the reproducibility of grading these tumours on glass slides and digital pathology.MethodsForty eight non-invasive urothelial bladder carcinomas were graded by three uropathologists on glass and on a digital platform using the 1973 WHO and 2004 ISUP/WHO systems.ResultsConsensus grades for glass and digital grading gave Cohen’s kappa scores of 0.78 (2004) and 0.82 (1973). Of 142 decisions made on the key therapeutic borderline of low grade versus high grade urothelial carcinoma (2004) by the three pathologists, 85% were in agreement. For the 1973 grading system, agreement overall was 90%.ConclusionsAgreement on grading on glass slide and digital screen assessment is similar or in some cases improved, suggesting at least non-inferiority of DP for grading of non-invasive urothelial carcinoma.

Highlights

Pathological grading of non-invasive urothelial carcinoma has a direct impact upon management.This study evaluates the reproducibility of grading these tumours on glass slides and digital pathology
Of 142 decisions made on the key therapeutic borderline of low grade versus high grade urothelial carcinoma
Most digital pathology (DP) validation studies focus on overall diagnostic concordance rather than tumour grade grading dysplasia and tumours is often identified as a source of discordance [4]

Summary

Introduction

Pathological grading of non-invasive urothelial carcinoma has a direct impact upon management.This study evaluates the reproducibility of grading these tumours on glass slides and digital pathology. Little data exist on the reproducibility of these grading systems, especially for the increasing popularity and transitioning to digital pathology (DP) assessment of tumours [2, 3] This is important given that a number of potential pitfalls are already known in some areas of DP, where digital screen appearances can be challenging to Nuffield Department of Surgical Sciences, University of Oxford, John. Recent reviews and guidelines highlight potential pitfalls of digitally grading atypia, including in urothelial cells [5,6,7] This view has been supported by a number of validation studies that have identified grade discrepancies in the small number of urothelial carcinomas included [8,9,10,11]. The aim of this study is to evaluate the intra-observer and inter-observer variation in grading of non-invasive urothelial bladder carcinomas, comparing glass and digital reporting/assessment methodologies

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