The Incidence and Clinicopathologic Characteristics of Patients Who Had False-Positive Fine-Needle Aspiration Results for Papillary Thyroid Cancer

Abstract

Purpose: Fine needle aspiration (FNA) is a well-established method for diagnosis of thyroid tumors. However, FNA sometimes fails to distinguish benign thyroid nodules from papillary thyroid carcinoma (PTC). The aim of this study was to evaluate the incidence and clinicopathologic characteristics of patients who had thyroidectomy due to consistent findings of PTC in FNA but turned out to bear no evidence of malignancy in surgically removed thyroids. Methods: We retrospectively reviewed 10,776 patients who underwent thyroid surgery from January 2009 to January 2019 due to suspicion for PTC, 40 of whom were diagnosed as benign in final histology. Results: We compared the clinical and pathologic characteristics of 2 groups, including subgroup analysis between Bethesda category V and VI. The false(+) rate for FNA was 0.4%. The ratio of patients aged ≥55 years was statistically higher in the false(+) group compared to the true(+) group. Age ≥55 years and Bethesda category V were risk factors for false(+) FNA in multivariate analysis. Conclusion: Although the false(+) rate is low (0.4%), surgeons should be aware of these circumstances and inform patients of the possibility of a false positive result in those with age >55 years, suspicion for malignancy on FNA (Bethesda category V), and low suspicion/benign for Korean thyroid imaging reporting and data system. To reduce unnecessary thyroidectomy, core needle biopsy or repeat FNA should be considered for a patient with these findings. Further large-scale studies are necessary to establish a firm conclusion.