The Development of a Novel Oral Cytologic Grading System

Abstract

While the Bethesda system represents one of the great success stories in cervical cytology, there has been little appetite for the adoption of a universal grading system for oral cytology. This could be explained by the general lack of interest in oral cytology due to a high percentage of false negative diagnoses, a great variation in technical quality and cellularity of oral smears as well as the use of inadequate sampling procedures. The lack of a standardized method for reporting oral cytology adversely affects proper management of patients with oral lesions. The emergence of Liquid-Based Cytology (LBC) with dramatic improvements in technical quality and cellularity of the cytology specimens has provoked a new interest in using this diagnostic modality for suspicious oral mucosal lesions. This chapter describes the adequacy criteria and minimum cellularity specifications of oral cytologic specimens, and proposes an oral cytologic grading system analogous to the Bethesda System for reporting cervical cytology based on LBC techniques. Using this classification, the terminology for reporting results obtained by oral cytology examination of class I and class II oral mucosal lesions is discussed with ample illustrations of the morphologic criteria and diagnostic categories. These include normal, reactive changes, changes including probably atypical reactive/low-grade lesions, low-grade squamous intraepithelial lesions, atypical probably high-grade changes, high-grade squamous intraepithelial lesion and invasive squamous carcinoma. While still at its infancy, this grading system provides a standardised and uniform method of reporting for the practising pathologist. To further validate the newly proposed classification scheme and discover the best cut-off value for distinguishing reactive/low grade lesions from high grade/squamous cell carcinoma, a simple and easy scoring method based on nine cytologic characteristics is proposed. This may well increase the specificity of the oral cytology test in a manner similar to that of the robust Papanicolaou test.