The Milan System for Reporting Salivary Gland Cytopathology and Updates

Abstract

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced into cytopathology practice more than 5 years ago. It classifies the salivary gland lesion into 6 diagnostic categories and provides the risk of malignancy (ROM) and clinical management guidelines for each category. More than 100 articles have confirmed the applicability of this reporting system in routine practice and its important role in providing a uniform reporting system for salivary gland fine-needle aspiration. At the same time, new questions and feedback for improvement have emerged, as well as opportunities for clarification. For example, questions related to the non-diagnostic category are multiple-fold. First, although the cytologic criterion of the non-diagnostic category is currently defined as “<60 lesional cells or normal salivary gland tissue within the clinical setting of an evident mass”, this has not been established or validated in the literature. Second, the ROM for the non-diagnostic category is high. Another question surrounds the interesting topic of sub-classifying current MSRSGC categories, as the risk of malignancy could vary in tumors of the same category. The last one concerns the incorporation of the ever-increasing number of molecular markers and antibody detection of gene re-arrangements, so-called next-generation immunohistochemistry (IHC) markers, into routine cytopathology practice. The quick application of next-generation sequencing into pathology practice provides an exciting opportunity for salivary gland cytopathology diagnosis.