Incorporation of the Milan system in reporting salivary gland fine needle aspiration cytology-An insight into its value addition to the conventional system

Background: Milan System for Reporting Salivary Gland Cytology (MSRSGC) was introduced to standardise the terminology and reporting of salivary gland cytology. The purpose of our study was to compare the conventional system and the proposed Milan System to look for concordance rates in cytohistopathologic correlation and any value addition to the conventional system. Methods: This was a retrospective cross sectional observational study. The fine needle aspiration cytology (FNAC) were reported in the conventional manner and were correlated with the surgical specimen. The cyto-histopathological correlation was studied to look for concordance rates. FNAC were retrospectively reviewed and were categorised according to the Milan system. These reports were correlated with surgical specimen category wise and concordance rates, risk of neoplasm (RON), risk of malignancy (ROM) were calculated. Results: Salivary gland FNAC done during the study period was 323 in number and histopathological correlation was available for 153 cases. The concordance rate of type specific diagnosis was 80.3% as per conventional system. With the application of Milan system, the concordance rates rose to 88.07% with an improvement of 6.67%(excluding non-diagnostic). RON and ROM for non-diagnostic (I)-50%, 50%; non-neoplastic (II)-22%,0%; atypia of unknown significance (III)-66%, 11%; benign neoplasm (IVA)-98%, 3%; salivary gland neoplasm of uncertain malignant potential (IVB)-93%,14%; suspicious for malignancy (V)-100%, 60% and malignant (VI) was 100%, 94%. Conclusion: The broad categorisation provided by the Milan system represents the gross rate of malignancy and helps in deciding the management plan and eventual surgical plan. Thus, it adds value to conventional reporting of salivary gland cytology.