Moving toward a systematic approach for reporting salivary gland cytopathology: cytohistological correlation with the application of the Milan system for risk stratification at a tertiary care center.

Abstract

Fine-needle aspiration cytology (FNAC) of salivary glands is a well-established technique that plays a critical role in the preoperative diagnosis of lesions. Despite its clinical utility, it remains one of the most challenging areas in cytopathology. This is because there is no consensus on how to report salivary gland cytopathology, which has resulted in inconsistent terminology and confusion in communication among cytopathologists and clinicians. A risk stratification of FNA diagnostic categories has been recently proposed to be useful in reporting. A retrospective study of FNAC of salivary gland lesions reported from 2014 to 2017 was performed. The performance of the cytology reporting system was evaluated with histological diagnosis serving as the gold standard. The aspirates were then categorized according to the Milan system. Furthermore, the risk of malignancy was calculated for all diagnostic categories. A total of 899 salivary gland aspirates were evaluated: 2.2% were nondiagnostic, 55.8% indicated nonneoplastic lesions, and 40.4% indicated neoplastic lesions. Histopathology was available for 172 cases. FNA had a sensitivity of 72.3% and a specificity of 92.6% with an overall diagnostic accuracy of 91.4% for differentiating malignant from benign tumors. A tiered classification scheme as proposed by the Milan system may prove helpful in effectively guiding clinical management of patients with salivary gland lesions. Our experience with this system helps to pave the way for the adoption of the Milan System for Reporting Salivary Gland Cytopathology.