Diagnostic Accuracy and Risk of Malignancy in Salivary Lesions Reclassified Using the Revised Milan System: A Single Institution Retrospective Analysis.

Abstract

Background: Salivary gland tumors represent 3% of head and neck neoplasms. Fine needle aspiration cytology (FNAC) is widely used for preoperative diagnosis, but its accuracy varies due to the diverse morphology of these tumors. The revised 2023 Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides updated risk of malignancy (ROM) estimates and guidelines for standardized reporting. This study reclassifies salivary gland FNAs using the revised MSRSGC and evaluates the ROM and diagnostic accuracy of each category.

Materials and methods: We retrospectively analyzed 184 FNAC samples of salivary gland lesions collected from January 2023 to June 2024. Each case was reclassified according to the 2023 Milan System. Histopathological follow-up was available for 46 cases. ROM was calculated for each category, and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were computed for two diagnostic groups: Group A (suspicious for malignancy and malignant) and Group B (malignant only).

Results: Of the 184 cases, 47.3% were benign and 14.1% were malignant. The ROM for non-diagnostic, non-neoplastic, atypia of undetermined significance (AUS), benign, SUMP, suspicious for malignancy, and malignant categories were 33%, 0%, 50%, 7.1%, 0%, 66.6%, and 100%, respectively. Group B had higher specificity and PPV, while Group A showed improved sensitivity and diagnostic accuracy.

Conclusion: The revised Milan System improves diagnostic accuracy in salivary gland FNAs. However, variations in ROM highlight the need for further studies to refine diagnostic challenges in certain categories.