Atypia of undetermined significance in the Milan System for Reporting Salivary Gland Cytopathology: Cystic versus non-cystic masses.

The term "Atypia" has been employed to describe a wide spectrum of cytomorphologic features associated with reactive/inflammatory processes as well as those suspicious for neoplasms in cytology. Similar to other cytopathology reporting systems, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has reserved the atypical category for cytology specimens lacking quantitative and/or qualitative cytomorphologic features to be diagnosed with confidence as either non-neoplastic or neoplastic. In MSRSGC, the atypical category is associated with a risk of malignancy and recommendation for clinical management. In this review, we discuss the value of atypical diagnostic category of MSRSGC in both cystic and non-cystic salivary gland lesions by evaluating our institutional case cohort.