Clinical diagnostic utility of ultrasound-guided fine needle aspiration biopsy in parotid masses

Background Fine needle aspiration (FNA) is a common diagnostic tool used in the initial evaluation of parotid masses. In the literature, variable diagnostic accuracy of FNA is reported. Therefore, when considering clinical management of these patients, the utility of FNA is unclear. The aim of this study was to determine the capability of ultrasound-guided FNA to differentiate between benign and malignant neoplasms. Further, the way in which FNA results affect clinical decision-making was assessed. Methods Retrospective data were collected for all patients who underwent parotidectomy at a large Canadian tertiary care center between 2011 and 2016. Patient demographics, preoperative imaging reports, preoperative FNA results, and final pathological diagnosis were analyzed. Results Of the 199 patients who underwent parotidectomy, 184 had preoperative ultrasound-guided FNA. There were a total of 13 non-diagnostic FNAs. In diagnosing malignancy, FNA had a sensitivity and specificity of 71.4% and 98.7%, respectively. The positive predictive value (PPV) was 83.3%. The negative predictive value was 97.5%. Of the non-diagnostic FNAs, 2 out of 13 (15.4%) were deemed malignant neoplasms on final pathology. Conclusion FNA is a useful adjunct in the work-up of parotid masses, but it should be used with caution. Due to limited sensitivity, it should not be relied upon as the sole determinant of a surgeon's management plan.