Application Of Milan System for Salivary Gland Cytopathology-A Prospective Study

Abstract

Introduction-Fine needle aspiration cytology (FNAC) of the salivary gland is a minimally invasive, safe, cost-effective diagnostic tool with apt sensitivity and specificity which varies from 86% to 100% and 90% to 100% respectively. To overcome this a uniform reporting system, the Milan system, was proposed by the American Society of Cytopathology (ASC) and the International Academy of Cytology (IAC), in 2015 in Milan, Italy. Prospective study to classify salivary gland lesions according to Milan System, assess the accuracy, risk of malignancy, and prognosis. Materials and Methods- All types of salivary gland lesions coming to the pathology department and their FNA smears, histopathology follow up along with clinical details were taken. These cases are classified according to the Milan system. False positive, false negative, true positive, and true negative cases were calculated by comparing with the final histopathological diagnosis and then the accuracy and risk of malignancy of each diagnostic category were calculated. Results- The sensitivity, specificity, negative predictive value, and positive predictive value were 65.2 %, 93.5 %, 46.62 %, and 96.87 % respectively. The overall diagnostic accuracy to differentiate the benign and malignant cases was 87%. Also, the risk of malignancy in each category was 33.3% (cat-I), 11.7%(cat-II), 100%(cat-III), 6.9(cat-IVa)%, 100%(cat-IVb), 100%(cat-V) and 100% (cat-VI)respectively. The highest risk of malignancy in the present study was noted in categories III and V. Conclusion-Milan system for reporting of salivary gland cytopathology provides good communication between pathologists and clinicians. This also results in lesser false positive and false negative results. The ROM in the present study was according to MSRSGC except for category III, atypia of undetermined significance which was 100%.