The Application of the Bethesda System for Reporting Cervical Cytology to Oral Cytology: An Institutional Study

Classification of oral cytology remains controversial under the Papanicolaou system. A uniform classification system would reduce inter-observer variability and also establish well-defined thresholds for management. This study evaluated the diagnostic accuracy of Bethesda (2014) system for dysplasia and malignancy in comparison to the Pap classification system and histopathological gold standard.
806 patients presenting with oral lesions were subjected to cytological diagnosis at our institution from 2017 to 2019. 100 of these patients underwent simultaneous biopsy for these lesions (subjects of this study). PAP-stained cytological smears from these patients were classified according to PAP and Bethesda 2014 systems and compared with their histopathological diagnosis. Bethesda classification showed 52.9% sensitivity, 86.7% specificity, PPV of 90.2% and NPV of 44.1% for detecting malignant/pre-malignant oral lesions. Sensitivity, specificity, PPV and NPV of the PAP system was 70%, 80%, 89.1% and 46.6% respectively. Statistically significant association was found between histopathological diagnosis and Bethesda classification: Spearman’s correlation coefficient being 0.537 (p<0.001). The Bethesda classification system uses well-defined criteria. Our study suggests that it renders cytopathological diagnosis of oral lesions more rigorous and reproducible. Oral scrape cytology reported under the Bethesda system can present clinicians with more interpretable, objective and actionable reports