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

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, nonneoplastic, 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. (C) 2018 S. Karger AG, Basel