Evaluation of two classification systems for oral epithelial dysplasia

Calibration improves the agreement in grading oral epithelial dysplasia-Findings from a National Workshop in Malaysia

INTRODUCTION

A major pitfall of many of the established oral epithelial dysplasia (OED) grading criteria is their lack of reproducibility and accuracy to predict malignant transformation. The main objective of this study was to determine whether calibration of practicing oral pathologists on OED grading could improve the reproducibility of the WHO 2017 and the binary OED grading systems.

METHODS

A nationwide online exercise was carried out to determine the influence of calibration on the reproducibility of the WHO 2017 and the binary OED grading systems.

RESULTS

A significant improvement was observed in the inter-observer agreement for the WHO 2017 OED grading system (K 0.196 vs. 0.448; Kw 0.357 vs. 0.562) after the calibration exercise. The significant difference (p = 0.027) in the level of agreement between those with five or more years and less than 5 years of experience was no more observed (p = 0.426) after the calibration exercise. The percent agreement for binary grading was significantly higher (91.8%) for buccal mucosal lesions as compared to lesions on the tongue after the calibration exercise.

CONCLUSION

This study validates the significance of calibration in improving the reproducibility of OED grading. The nationwide exercise resulted in a statistically significant improvement in the inter-observer agreement for the WHO 2017 OED grading system among a large number of oral pathologists. It is highly recommended that similar exercises should be organized periodically by professional bodies responsible for continuing education among oral pathologists to improve the reliability of OED grading for optimal treatment of oral potentially malignant disorders.

Oral leukoplakia classification and staging system with incorporation of differentiated dysplasia

OBJECTIVES

A classification and staging system for oral leukoplakia (OL) was introduced to promote uniform reporting. In this system, size and the histopathologic diagnosis are assessed and combined in a staging system. The various stages could be predictive for malignant transformation of OL. Differentiated dysplasia (DD) was recently recognized as an important architectural pattern of dysplasia and is highly associated with malignant transformation (MT) of OL. In the present study, DD was incorporated in the OL-system. The aim of the present study was to test the adapted system on a cohort of patients with OL.

PATIENT AND METHODS

The group consisted of 140 patients. The size, absence or presence and degree of classic dysplasia (CD) and DD were incorporated into the OL-system.

RESULTS

In 31/140 patients, MT occurred. Size was not statistically significant with MT (p = 0.422). The presence of dysplasia was predictive for MT (p = 0.003), whereby severe CD and DD were highly statistically significant for MT (p = 0.008). Stage IV was statistically significant for MT (p = 0.011).

CONCLUSIONS

The present study emphasizes the value of the slightly modified OL-system with incorporation of DD in uniform reporting of OL and the value in predicting MT.

The clinical utility of contemporary oral epithelial dysplasia grading systems

INTRODUCTION

Clinical management of oral potentially malignant disorders relies on accurate histopathological assessment of the presence and grade of oral epithelial dysplasia. Whilst adjunctive laboratory tests have provided useful prognostic information, none are in widespread clinical use. This study was performed to assess the clinical utility of two contemporary oral epithelial dysplasia grading systems.

METHODS

Patients were identified from a clinical database. Oral epithelial dysplasia grading was performed by three oral and maxillofacial pathologists blinded to clinical outcome using the WHO 2017 system and a binary classification. The primary outcome measure was the development of oral squamous cell carcinoma, termed 'malignant transformation'.

RESULTS

131 cases satisfied the inclusion criteria, of which 23 underwent malignant transformation. There was substantial inter-rater agreement between the study pathologists for both grading systems, measured using kappa statistics (κ = 0.753-0.784). However, there was only moderate agreement between the consensus WHO 2017 dysplasia grade for the study against the original grade assigned by a pool of six pathologists in the context of the clinical service (κ = 0.491). Higher grade categories correlated with an increased risk of developing cancer using both grading systems.

CONCLUSION

This study demonstrates that the WHO 2017 and binary grading systems are reproducible between calibrated pathologists and that consensus reporting is likely to improve the consistency of grading. The WHO and binary systems were prognostically comparable. We recommend that institutions implement consensus oral epithelial dysplasia grading and prospectively audit the effectiveness of risk stratifying their patients with oral potentially malignant disorders. (249 words).