1153 “To FNA Or to Not FNA, That Is the Question.” A 5-Year Retrospective Epidemiological Study Of 238 Surgical Parotid Cases Treated at An East Yorkshire OMFS Unit

Fine needle aspiration (FNA) is a surgical procedure used to aid with diagnosis and subsequent treatment planning. This study compares FNA histology with final histology (gold standard) for diagnostic accuracy in parotid surgery patients. Method A retrospective investigation of patient records from January 2014-January 2019 was performed to find eligible patients that underwent parotid surgery. Histology reports of the ultrasound (US) FNA and final parotid sample were compared for diagnostic accuracy and ability to differentiate between malignant & benign tumours. Results 240 parotid surgeries on 238 patients were undertaken between 2014-2019 under OMFS and ENT specialities. 137 US FNA’s were performed, of these, there was an 85% diagnostic rate. Of the diagnostic FNA’s 79% reach gold standard, with the histology matching that of the final histology. Of the 24 without diagnostic accuracy, 2/3 were still able to differentiate between malignant and benign lesions. Overall, the US FNA’s were able to differentiate malignant and benign parotid lesions in 93% of cases. Conclusions The audit has proven US FNA to be an accurate diagnostic test, it gives extra data to aid in the decision making and planning for parotid surgeries. Although US FNA has shown to be more accurate in diagnosing benign parotid tumours; it is useful in detecting cellular change which could be indicative of malignancy.