Diagnostic Utility of the Milan System for Reporting Salivary Gland Cytopathology With Cytohistological Correlation

Fine needle aspiration cytology (FNAC) is an affordable diagnostic method for assessing salivary gland lesions. However, interpreting cytology results of salivary gland FNACs can be difficult due to the wide variety of lesion morphologies and overlapping features among different tumour subtypes. To address this challenge, the "Milan System for Reporting Salivary Gland Cytopathology" (MSRSGC) was introduced to aid in diagnosis, management, and to determine the risk of malignancy (ROM) across different categories. Our study aims to assess the cytological spectrum of salivary gland lesions on fine needle aspiration cytology and evaluate the diagnostic utility of MSRSGC with histological correlation.

Cytology slides of FNAC over an 11-year retrospective period were retrieved, reviewed and categorized based on the MSRSGC. Histological findings were correlated with cytological findings in cases where excision specimens were received for histopathological evaluation.

A total of 111 cytology cases were categorized by MSRSGC. All cases were clinically followed up, and histopathological correlation was available for 34 cases. The overall specificity for diagnosis of neoplastic lesions on cytology was 71.40%, sensitivity was 96%, and accuracy was 90.63%. The specificity for diagnosis of malignant lesions on cytology was 95.83%, sensitivity was 100%, accuracy was 96.29%, positive predictive value was 75%, and negative predictive value was 100%.

FNAC is an excellent, non-invasive and resource-efficient tool for diagnosing salivary gland lesions. The MSRSGC six-tier system aids in managing tumours with complex morphology and overlapping cytological characteristics.