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

Abstract

The prognostic impact of ultrasound features of thyroid nodules is debated. We explore the correlation between nodule size, echogenicity on US, and malignancy. We performed a retrospective review of thyroid nodules undergoing ultrasound guided FNA (US-FNA) at our institution between 01/2008-05/2013. In all, 2,403 nodules from 2,293 patients (age range 14-91, mean 54, median 56, M: F-1:3.2) 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%). 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.