Sonographic Features of Nodular Hashimoto Thyroiditis

The aim of the study was to analyze the sonographic features of nodular Hashimoto thyroiditis (HT) in patients with diffuse background thyroiditis and normal background thyroid parenchyma.

Eighty-six patients who had fine-needle aspiration biopsy of 100 thyroid nodules confirmed to be HT and a thyroid ultrasound within 1 year of the biopsy were included in the study. Retrospective analysis of several sonographic features of each nodule was then performed.

The mean age of patients with nodular HT was 53 years, 84% of which were female. Nodular HT occurred in a background of diffuse thyroiditis in 85% and in a homogeneous normal background in 15%. Ninety-three percent of nodules were completely solid and 7% of nodules were cystic and solid. Although the sonographic appearance of nodular HT was variable, the most common appearance was a solid (93/100) and hypoechoic nodule (44/100) with a thin hypoechoic halo (42/100) without calcifications (96/100). On color Doppler, 17% of nodules showed peripheral hypervascularity, 14% of nodules were diffusely hypervascular, 34% were iso vascular, 32% were hypovascular, and 3% were avascular. The sonographic appearance of nodular HT was not significantly different in patients with diffuse background thyroiditis compared with those without background thyroiditis.

The sonographic appearance of nodular HT is variable, but the most common appearance is a solid sharply circumscribed hypoechoic nodule with thin hypoechoic halo without calcification. There was no significant difference in the appearance of nodular HT in patients with diffuse background thyroiditis compared with patients with normal background thyroid parenchyma.