Sonographic Features Predictive of Benign Thyroid Nodules: Important of Avoiding Unnecessary Ultrasound-Guided Fine Needle Aspiration Biopsy

PURPOSE: We aimed to develop a feature-oriented approach to characterize benign thyroid nodules that do not require ultrasound-guided fine needle aspiration (US-guided FNA). MATERIALS AND METHODS: We finally reviewed 374 patients (298 women and 76 men) having complete medical records and US-guided FNA. The nodular content (solid or cystic); echogenicity (hyperechoic, isoechoic, hypoechoic) relative to strap muscle; calcification (micro, coarse, or absent); nodular margin (well-defined or ill-defined); vascularity (increased or decreased) relative to the normal part of the thyroid tissue; and lymphadenopathy (neck node with calcification or short-axis > 10 mm) were evaluated. Finally, all US features were classified into 3 category: 1). Benign nodules that did not require US-guided FNA but follow-up 6 months to 12 months later was required; 2). Indeterminate, which can be follow-up 6 months later or US-guided FNA; 3).Atypical nodules or suspected carcinoma, which required US-guided FNA. RESULTS: Of the 374 nodules, 354 (95%) were benign and 20 (5%) malignant. There were 260 thyroid nodules (69.5%) that proved benign on cytology. The following US features were classified as category 1: without calcification, well-defined margins, without increase vascularity and no lymphadenopathy. There were 60 thyroid nodules (16%) classified as category 2. Indeterminate. The remaining 54 thyroid nodules (14.4%) with US features of calcification, blurred margins, increase vascularity, lymphadenopathy were classified as category 3. CONCLUSION: The US features of no calcification, no increased vascularity, well-defined margin, and no lymph node enlargement are highly predictive of benign nodules, and thereby, aspiration biopsy can be avoided in clinical practice.