The reliability of thyroid nodule ultrasound features and size to predict malignancy in fine needle aspiration specimens: Practical utility for the evaluating pathologist.

ABSTRACT

BACKGROUND: The prognostic impact of ultrasound features of thyroid nodules is debated. We explore the correlation between nodule size, echogenicity on US, and malignancy. METHODS: We performed a retrospective review of thyroid nodules undergoing ultrasound guided FNA (US-FNA) at our institution between 01/2008-05/2013. RESULTS: In all, 2,403 nodules from 2,293 patients (age range 14-91, mean 54, median 56, M F-13.2) underwent US-FNA. 766 nodules were resected, 337 were malignant (size range 0.4-8.7 cm, median 2 cm, mean 2.37 cm,) and 429 were benign (size range 0.5-9.7 cm, median 2.5 cm, mean 2.79 cm). The malignant diagnoses included classical variant of PTC 77 (size range 0.5-5.5 cm, mean 1.5 cm), follicular variant of PTC 209 (size range 0.14-7.5 cm, mean 2.1 cm), tall cell variant of PTC 7 (size range 0.5-2.4 cm, mean1.4 cm), poorly differentiated carcinoma 5 (size range 5-8.7 cm, mean 6.42 cm), follicular carcinoma 27 (size range 0.5-7 cm, mean 3.03 cm), and oncocytic follicular carcinoma 9 cases (size range 1.4-7.2 cm, mean 3.2 cm). Of the malignant nodules with echogenicity reported on US, 93 were hypoechoic, 26 hyperechoic, 20 isoechoic, and 76 heteroechoic; increased vascularity on US was seen in 69/337 (20%). On US, 105 benign nodules were reported as hypoechoic, 35 hyperechoic, 43 isoechoic, and 100 as heterogeneous; increased vascularity on US was seen in 88/429 (20%). CONCLUSIONS: A malignant diagnosis was more common in thyroid nodules ≤1.0 cm. No differences were noted in the US-features of benign and malignant thyroid nodules.