Park VY, et al. - Given that the malignancy risk of thyroid nodules differs according to Bethesda category, ultrasound features, and nodule size, experts compared frequencies and malignancy rates of Bethesda categories according to size and ultrasound assessment. The frequency of the benign cytology was statistically higher in the >10 mm group while comparing the ultrasound suspicious nodules ≤10 mm and >10 mm, whereas the nondiagnostic and suspicious for malignancy cytology were higher in the ≤10 mm group. The malignancy rate of the benign cytology group was higher, in ultrasound suspicious nodules ≤10 mm but that of the suspicious for malignancy cytology group was lower than the >10 mm group.