Can We Omit Intraoperative Frozen Section According to the Result of the Preoperative Fine-needle Aspiration Cytology of a Thyroid Nodule? / 대한내분비외과학회지

ABSTRACT

PURPOSE: Fine needle aspiration (FNA) is a useful preoperative diagnostic tool for thyroid nodule because of the high sensitivity and specificity. The aim of this study is to determine the necessity of intraoperative frozen section (IOFS) after fine needle aspiration. METHODS: Data of 534 patients with a single thyroid nodule who underwent thyroidectomy from June 2006 to August 2013 were reviewed retrospectively. FNA was performed preoperatively in all patients and IOFS was performed selectively according to the intraoperative findings and FNA results. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNA and IOFS for malignant nodules were analyzed. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FNA for malignant nodules were 100%, 95.5%, 99.8%, 100%, and 99.8%, respectively. All nodules diagnosed as benign by FNA were reaffirmed as benign nodules by permanent sections. When the result of FNA was suspicious for malignancy, specific features of preoperative ultrasound, including hypoechoic, size<10 mm showed high positive predictive value and accuracy (98%, 86.9%, and 100%, 78.7% respectively). CONCLUSION: Performance of IOFS was not necessary when the result of FNA was consistent with malignancy or benign. However when the result of FNA was non-diagnostic or atypia, IOFS should be performed for more accurate detection of malignancy. When the result of FNA is suspicious for malignancy, IOFS is restrictively useful for excluding benign nodules using the features of ultrasound. In addition, IOFS is not useful in finding malignant thyroid nodules when the result of FNA is follicular neoplasm.