Risk stratification of parotid neoplasms based on intraoperative frozen section and preoperative fine needle aspiration cytology

Purpose This study aims to determine the relationship of frozen section (FS) to final histology and determine how incorporating FS may change preoperative malignancy risk estimates based on preoperative fine needle aspiration cytology (FNAC). The secondary aim is to determine if FS is useful in influencing intraoperative decision-making. Methods Retrospective review of 426 intraoperative FS for parotidectomies performed for primary parotid lesions. Results Risk of malignancy with a benign FS was 2.5%, with indeterminate 36.1%, and with malignant 100%. Incorporating FS to fine needle aspiration for cytology helped to stratify malignancy risk especially in the Milan categories of atypia of undetermined significance, neoplasm of uncertain malignant potential and non-diagnostic categories, where a malignant FS increased malignancy risk significantly. FS was only able to identify 11% of high-risk histological subtypes for which a neck dissection would be recommended. Conclusions FS may be used to stratify malignancy risk intraoperatively but has limited utility in clinical decision-making to perform a neck dissection and more extensive parotid resection in high-risk histological subtypes.