Cytomorphological Spectrum and Classification of Salivary Gland Lesions According to Milan System of Reporting

Background: Salivary gland lesions comprise a diverse group of non-neoplastic, benign, and malignant conditions with overlapping cytomorphological features. Fine-needle aspiration cytology (FNAC) is widely used as a minimally invasive first-line diagnostic tool for the evaluation of these lesions. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides a standardized reporting framework with defined risk of malignancy (ROM) and management recommendations. The aim is to evaluate salivary gland lesions using FNAC and classify them according to the Milan System to determine their diagnostic significance. Material and Methods: This retrospective observational study was conducted in the Department of Pathology of a tertiary care centre over a period of three years from January 2022 to January 2025. A total of 50 salivary gland FNAC cases were included. Archived FNAC smears stained with MGG, PAP, and H&E were reviewed along with available histopathological sections and clinical records. Cases were categorized according to the Milan System for Reporting Salivary Gland Cytopathology. Cytohistopathological correlation and ROM were assessed wherever histopathology was available. Statistical analysis was performed using SPSS software. Results: Benign neoplasms (Category IVa) constituted the largest group comprising 24 (48%) cases, followed by non-neoplastic lesions accounting for 13 (26%) cases. Pleomorphic adenoma was the most common benign neoplasm, while chronic sialadenitis was the predominant non-neoplastic lesion. Categories III and IVb demonstrated higher ROM ranging from 33% to 50%, whereas Categories V and VI showed a ROM of 100%. FNAC demonstrated a sensitivity of 78.6%, specificity of 97.2%, positive predictive value of 91.6%, negative predictive value of 92.8%, and overall diagnostic accuracy of 93.3%. Conclusion: The Milan System proved to be a practical and effective framework for standardized reporting of salivary gland cytology. FNAC demonstrated high specificity and diagnostic accuracy, reaffirming its utility as a reliable first-line diagnostic modality for salivary gland lesions.

Keywords: Fine-needle aspiration cytology; Milan System; Salivary gland lesions; Risk of malignancy; Pleomorphic adenoma.