Utility of the Milan system for reporting salivary gland cytopathology: A retrospective 5 years study

BACKGROUND Fine-needle aspiration cytology (FNAC) is an established technique for preoperative diagnosis of salivary gland lesions; however, lack of a uniform reporting system has been a handicap. The main aims of this study were to evaluate the utility of the - "The Milan System for Reporting Salivary Gland Cytopathology" (MSRSGC) and ascertain the risk of malignancy (ROM) for each category. METHODS All salivary gland FNACs over 5 years (January 2014-December 2018) were reviewed and assigned a diagnostic category from the MSRSGC. Clinical data were taken from Cytology records. Cytodiagnosis was correlated with histopathology wherever available and ROM was calculated. RESULTS A total of 120 salivary gland FNACs were studied. Age ranged between 5 and 85 years, male:female ratio was 2:1 and parotid was the commonest gland aspirated. Cases were reclassified as I non-diagnostic (2.5%), II non-neoplastic (15%), III atypia of uncertain significance-AUS (1.7%), IV A neoplasm benign (50%), IV B neoplasm of uncertain malignant potential (12.5%), V suspicious for malignancy (5%), and VI malignant (13.3%). Follow-up was available in 70 (58.3%) cases. The sensitivity, specificity, negative predictive value, and positive predictive value were 92.3%, 100%, 100%, and 98.27% respectively. ROM was non-neoplastic (0%), AUS (50%), neoplasm benign (0%), neoplasm of uncertain malignant potential (28.6%), suspicious for malignancy (100%), and malignant (100%). CONCLUSION Salivary gland FNAC is a reliable diagnostic tool and the "Milan system" will further increase FNA reliability, help risk stratification, and improve patient care.