Thyroid Nodules with Bethesda System III Cytology: Can Ultrasonography Guide the Next Step?

Abstract

BACKGROUND: This study was designed to evaluate the feasibility and the role of thyroid ultrasound (US) in predicting malignancy for Bethesda system III nodules and to suggest management guidelines for these nodules. METHODS: A total of 155 thyroid nodules with Bethesda system III cytology in 155 patients with surgery or follow-up repeat FNA were included in this study. On the basis of US features, final assessment for thyroid nodules were prospectively classified into one of three categories: (1) probably benign, (2) low suspicious for malignancy, and (3) suspicious for malignancy. The clinicopathologic characteristics of patients and US features of nodules were compared according to malignancy and benignity. RESULTS: Of the 155 Bethesda system III nodules, 69 (44.5%) underwent surgery without repeat FNA and 86 (55.5%) nodules underwent repeat FNA, and a malignancy rate of 55.5% (86/155) was determined. Thyroid nodules with concurrent thyroid cancer were more likely to be malignant (P<0.001). The malignancy rate of sonographically suspicious for malignancy was 100%, higher than the 58% of sonographically low suspicious for malignancy, and 7.7% of sonographically probably benign nodules (P<0.001). CONCLUSIONS: US assessment may help the clinician decide between surgery and repeat FNA for managing Bethesda system III nodules. When the US assessment for the thyroid nodules is suspicious for malignancy, repeat FNA may be unnecessary and surgery should be considered.