(206) FNA and Frozen Section's Ability to Determine Extent of Parotidectomy

Introduction: Fine needle aspiration (FNA) is the most common initial diagnostic modality used in the evaluation of a parotid mass. Although FNA can provide useful preoperative information, some studies suggest FNA alone is insufficient for proper surgical decision-making and advocate for the use of intraoperative frozen section because of its superior accuracy in detecting malignancy and tumor subtyping. The primary aim of this study is to compare the diagnostic actionability, accuracy, and ability to accurately predict extent of surgery for FNA and frozen section during the evaluation of a parotid mass.

Methods: A retrospective chart review of patients who underwent parotidectomy for a parotid mass from 1/1/2015 to 1/30/2022 was conducted. Actionability was defined as a pathology diagnosis or the histologic grade of a lesion, as this provided clear and useful information for the surgeon to act upon. Diagnostic accuracy was determined by comparing FNA and frozen section results to final pathology. Accuracy of extent of surgery was determined by comparing predicted extent of surgery from the FNA or frozen section result to the extent of surgery predicted by the final pathology.

Results: 626 patients were included in this study. FNA was obtained in 396 (63%) patients, while all neoplasms were evaluated by frozen section analysis. FNA diagnosis was actionable in 318 (80%), while frozen section diagnosis was actionable in 616 (98%) patients. 294 (92.5%) FNA diagnoses were accurate compared to 600 (98%) frozen section diagnoses. The FNA diagnosis predicted appropriate extent of surgery in 294 (74%) while the frozen section diagnosis predicted appropriate extent of surgery in 600 (96%,). Among the 396 patients with FNA, frozen section was significantly more likely to accurately predict appropriate extent of surgery compared with FNA (p < 0.001).

Conclusions: Frozen section is more likely to yield actionable and accurate results compared to FNA. Additionally, frozen section is better than FNA in predicting the appropriate extent of surgery.