Cytology of Salivary Gland Tumours: Application of the Milan System and Diagnostic Challenges – A Retrospective Study

Abstract

Background: Fine needle aspiration cytology (FNAC) is a primary diagnostic tool for salivary gland lesions. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides standardized categorization with defined risk of malignancy (ROM).

Aim: To evaluate salivary gland cytology cases using the Milan system and analyze diagnostic challenges with histopathological correlation.

Methods: A retrospective study was conducted at Nalanda Healthcare and Diagnostics, Patna, from 10 November 2025 to 10 January 2026. Thirty FNAC cases of salivary gland lesions were categorized according to the Milan system. Histopathological follow-up was available in 26 cases (86.7%). Statistical analysis included calculation of ROM, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and chi-square test.

Results: The most common Milan category was Category IVa (Benign neoplasm) (40%), followed by Category II (Non-neoplastic) (20%). Histologically confirmed malignancy rate was 30.8% (8/26). Sensitivity and specificity of FNAC for detecting malignancy were 62.5% and 94.4%, respectively. Overall diagnostic accuracy was 84.6%. The highest ROM was observed in Categories V and VI (100%).

Conclusion: The Milan system provides structured risk stratification and improves communication between cytopathologists and clinicians. While FNAC shows high specificity, indeterminate categories remain a diagnostic challenge requiring histopathological confirmation.

Keywords: Salivary gland cytology; Milan system; FNAC; Risk of malignancy; Diagnostic accuracy.