Validating the Utility of the Milan System of Reporting Salivary Gland Cytopathology for the Diagnosis of Salivary Gland Fine-Needle Aspirates in a North Indian Tertiary Care Center and Comparing the Risk of Malignancy with its Two Editions.

Abstract

Background: Salivary gland (SG) fine-needle aspiration (FNA) is a well-accepted tool for preoperative management of salivary gland lesions (SGLs). First and second editions of the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) were published in the years 2018 and 2023, respectively. The MSRSGC aims to improve patient care by providing better communication between clinicians and institutions. It has six ascending diagnostic categories having a definite risk of malignancy (ROM) and corresponding management schema. Our study assessed the incidence and corresponding ROM of each MSRSGC category within a tertiary care northern India referral center and compared each ROM with those laid down in the two editions of the MSRSGC.

Aims and objectives: The main aims and objectives are as follows:1. Validating the utility of the MSRSGC for the diagnosis of SG-FNAs in a North Indian Tertiary Care Center.2. Comparing the Risk of Malignancy with its Two Editions.

Materials and methods: Data on SG-FNAs performed between 01.01.2010 and 31.03.2024 were searched from the hospital information system. The cytopathology and histopathological slides were retrieved, and each case was separately reviewed and retrospectively classified into the I) non-diagnostic (ND), II) non-neoplastic (NN), III) atypia of undetermined significance (AUS), IVA) benign neoplasms (NB), IVB) SG neoplasm of uncertain malignant potential (SUMP), V) suspicious for malignancy (SFM), or VI) malignant categories according to the MSRSGC. Cyto-histopathological correlation analysis was performed, and the ROM for each category was calculated.

Results: A total of 793 such cases were obtained. Histopathological follow-up was available in 267 cases, which included 2 (0.7%) ND, 29 (10.9%) NN, 5 (1.9%) AUS, 190 (71.2%) NB, 11 (4.1%) SUMP, 10 (3.7%) SFM, and 20 (7.5%) malignant cases. The calculated ROM for these ascending categories were 0%, 27.6%, 60%, 11.8%, 45.5%, 90%, and 100%, respectively.

Conclusion: MSRSGC is a valuable means to standardize the reporting and preoperatively stratify SGLs as per the ROM for each ascending risk category. This study, to the best of our knowledge, is the largest Indian study to authenticate the utility and reproducibility of the MSRSGC in our tertiary care institute.