Evaluation of accuracy of salivary gland fine needle aspirates using the Milan System for Reporting Salivary Gland Cytopathology.

Abstract

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a standardised six-tier reporting format aimed at ensuring better communication and improved patient management. The main objectives of our study were to classify salivary gland fine needle aspirates into six categories of the MSRSGC and assess risk of malignancy (ROM), specificity, sensitivity, positive predictive value, and negative predictive value. This retrospective study covered a period of three years from January 2017 to December 2020. All salivary gland FNAs performed in the above period were retrieved and classified into six categories based on the Milan system. Histopathological diagnosis was also retrieved wherever available. Using histopathological diagnosis as the gold standard, ROM was calculated. Specificity, sensitivity, positive and negative predictive values, and diagnostic accuracy were also assessed. Out of the 202 salivary gland FNAs, histopathological diagnosis was available in 102 cases. ROM for the Non-Diagnostic, Non-Neoplastic, Atypia of Undetermined Significance (AUS), Benign, Salivary Gland Neoplasm of Uncertain Malignant Potential (SUMP), Suspicious for Malignancy (SM), and Malignant categories was 30%, 8.3%, 25%, 3.9%, 33.3%, 71.4%, and 93.3% respectively. Highest specificity and diagnostic accuracy were achieved when only Malignant and SM were considered as positive results. Maximum sensitivity was observed when AUS, SUMP, SM, and Malignant were included in positive test results. The MSRSGC is an excellent system for accurately classifying salivary gland FNAs with better reproducibility of reports and enhanced communication between pathologist and surgeon.