Milan System Categorization and Reporting of Salivary Gland Tumors: A Literature Review

Abstract

Abstract Salivary gland tumors (SGTs) are uncommon and represent about 6% of all head and neck tumors and 0.3% of all malignant tumors worldwide. The reporting system of SGTs before 2018 was individualized and may be problematic and confusing for some pathologists and clinicians. In 2018, the Milan Categorizing System for Salivary Gland Tumors (MSRSGC) was developed by an international consortium of experts and endorsed by the American Society of Cytopathology and the International Academy of Cytology; the aim was to standardize the reporting terminology to replace the conventional, descriptive interpretation for salivary gland fine needle aspirations for better communication between clinicians and between institutions. This review aims to stand on the extent of the MSRSGC in resolving the conflicts among pathologists and clinicians and highlight the problems that have been reported through studying the published literature. Since its development, the MSRSGC has provided to some extent a unified reporting system that elevated the communications among pathologists and clinicians. In addition, the MSRSGC has provided information about the risk of neoplasia (RON), risk of malignancy, and line of management for each category; however, most discussions have shown that some cases in the intermediate group are still indicating conflicts in its diagnosis and reporting, especially those of SGTs of uncertain malignant potential (SUMP) with distinct cellular features, such as basaloid, oncocytic, and squamoid features and a need to be recategorized individually, and the strength of the system in the category toward diagnostic feature of malignancy.