Ancillary testing strategies in salivary gland aspiration cytology: A practical pattern-based approach

Fine needle aspiration of salivary gland tumors is a common preoperative triage as it is useful in determining which patients should undergo surgical resection and in guiding the extent of surgery in those cases deemed appropriate for resection. While a specific diagnosis can be achieved on a cytologic specimen in many cases, there is also a considerable amount of morphologic diversity that prevents such confident preoperative classification and in these cases it can be a challenge to confidently determine if a tumor is benign or malignant. Recently, a pattern based risk stratification approach was proposed for salivary gland cytology in which basaloid neoplasms are separated by stromal characteristics and oncocytoid neoplasms are separated primarily by background material such as mucus. In addition to potentially providing a stratification in risk of malignancy for salivary gland tumors, this approach is also useful to narrow differential diagnostic considerations and guide ancillary testing. In this review we use this proposed pattern based approach as a framework to discuss immunostains and fluorescence in situ hybridization studies which we find useful in our practice.