A retrospective cytohistological study on the application of the Milan System for Reporting Salivary Gland Cytopathology in Zamboanga City Medical Center: a 5-year single-center study.

INTRODUCTION: The cytologic evaluation of salivary gland tumors is challenging due to marked morphologic diversity and overlap between benign and malignant lesions. Fine-needle aspiration biopsy is a minimally invasive and widely used initial diagnostic tool, and the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was developed to standardize reporting and improve diagnostic consistency. MATERIALS AND METHODS: This retrospective study evaluated the application of the MSRSGC at Zamboanga City Medical Center from January 2020 to January 2025 by correlating fine-needle aspiration biopsy cytologic diagnoses with histopathologic outcomes. Concordance, risk of malignancy, risk of neoplasm, and diagnostic performance metrics were calculated. RESULTS: Fifty-nine cases with available surgical follow-up were included. Overall cytohistologic concordance was 83.1%, with the highest agreement observed in Categories III (Atypia of Undetermined Significance), IV-B (Salivary Gland Neoplasm of Uncertain Malignant Potential), and VI (Malignant), followed by Category IV-A (Benign Neoplasm). Agreement beyond chance was moderate and statistically significant (Cohen's κ = 0.40; 95% confidence interval [CI], 0.19-0.61; P < 0.001). The overall risk of malignancy and risk of neoplasm were 32.26% and 52.78%, respectively. The sensitivity for detecting malignancy was 56% (95% CI: 21-86) and specificity was 74% (95% CI: 60-85). The positive predictive value was 28% (95% CI: 10-53), while the negative predictive value was high at 90% (95% CI: 77-97). CONCLUSIONS: Overall diagnostic accuracy was 71% (95% CI: 58-82). These findings support the clinical utility of the Milan System as a triage tool, particularly for ruling out malignancy, while emphasizing strict diagnostic criteria, clinic-radiologic correlation, and adequate sampling.