Background: This study aimed to assess solid thyroid nodule (STN) cases with discordant sonographic and cytological diagnoses and to compare the diagnostic indices of these modalities.
Methods: From January 2013 to December 2013, a single radiologist performed consecutive thyroid ultrasonography (US) and US-guided fine-needle aspiration (US-FNA) to diagnose 347 STNs in 347 patients. Each STN was classified into 1 of 5 categories according to the US diagnosis before US-FNA: "benign," "probably benign," "indeterminate," "suspicious for malignancy," or "malignant." We assessed cases where the sonographic and cytological STN diagnoses were discordant, using the final diagnosis as the reference standard.
Results: Of the 347 STNs, 279 (80.4%) had a final diagnosis confirmed. The "benign," "probably benign," and "malignant" US categories showed high concordance with the cytological diagnoses, whereas the "suspicious for malignancy" US category revealed only a 62.2% concordance rate. The prevalence of indeterminate cytology was higher in the "indeterminate" and "suspicious for malignancy" US categories than other US categories. STNs with indeterminate cytology showed a higher malignancy rate in the malignant US categories. When STNs classified into indeterminate categories from the sonographic (n = 49) and cytological (n = 18) diagnoses were excluded, the sensitivity, specificity, and accuracy of the sonographic and cytological diagnoses were 95.5 and 98.8%, 92.1 and 100%, and 93.0 and 99.6%, respectively.
Conclusion: The "suspicious for malignancy" US category showed higher discordance with cytological diagnoses than other US categories, and the diagnostic value of US was lower than that of cytology.
Keywords: cytology; discrepancy; solid; thyroid nodule; ultrasonography.
© 2015 Wiley Periodicals, Inc.