Application of the Milan System for Risk Stratification and Its Comparison with a Previous Reporting System of Parotid Gland Cytopathology in a Tertiary Care Centre

Abstract

Objective: To compare the recently proposed Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) with the four-tiered reporting system (FTRS) followed at our institute. Methods: Parotid gland fine-needle aspirates reported over a period of 5 years were analysed. These aspirates had been placed into 4 categories according to the FTRS: unsatisfactory (UNS), no evidence of malignancy/negative (NEG), inconclusive for malignancy (INC), and diagnostic for malignancy/positive (POS). Aspirates with follow-up histopathology were then categorized according to the MSRSGC as follows: non-diagnostic, non-neoplastic, atypia of unde­termined significance (AUS), neoplasm, suspicious for malignancy, and malignant. The risk of malignancy (ROM) was calculated. Results: A total of 893 parotid region aspirates were evaluated and histopathology was available for 190 cases (21%). ROM in MSRSGC groups, namely non-diagnostic, non-neoplastic, AUS, neoplasm, suspicious for malignant neoplasm, and malignant, was 44, 8, 0, 12, 81 and 100%, respectively. ROM in FTRS groups, namely UNS, NEG, INC, and POS, was 45, 13, 67 and 100%, respectively. Conclusions: MSRGC and FTRS are comparable with respect to the ROM across groups. Compared to FTRS, the further subcategorisation of the non-malignant group, the use of specific nomenclature, and the reproducibility of MSRGC provide proper risk stratification, thereby guiding better management and resulting in improved patient care.