The Milan System for Reporting Salivary Gland Cytopathology: Benefits and Cautions

Fine-needle aspiration (FNA) is a well-established procedure for the diagnosis and management of salivary gland lesions despite challenges imposed by their diversity, complexity, and cytomorphological overlap. Until recently, the reporting of salivary gland FNA specimens was inconsistent among different institutions throughout the world, leading to diagnostic confusion among pathologists and clinicians. In 2015, an international group of pathologists initiated the development of an evidence-based tiered classification system for reporting salivary gland FNA specimens, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC). A corresponding MSRSGC Atlas was published in February 2018. The MSRSGC consists of 6 diagnostic categories that incorporate the morphologic heterogeneity and overlap among various nonneoplastic, benign, and malignant lesions of the salivary glands. In addition, each diagnostic category is associated with a risk of malignancy and management recommendations. The main goal of the MSRSGC is to improve communication between cytopathologists and treating clinicians, while also facilitating cytologic-histologic correlation, quality improvement, and sharing of data from different laboratories for research. Herein, we review the benefits and the limitations of the MSRSGC, as well as the challenges of implementing this new reporting system in routine practice.