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.