Intrathyroidal ectopic thymus and sonoelastographic findings

Abstract

Background: Intrathyroidal ectopic thymus (IET) can be misdiagnosed as thyroid nod-ules. Purpose: The purpose of this study is to evaluate the sonoelastographic findings of IET in pediatric population. Methods: Twelve children who had been examined with ultrasound (US) and strain elastography between December 2012 and December 2019 were included in this retrospective study. The pa-tients' demographics and ultrasonographic findings, including the location, margin, shape, diame-ters, volume, structure, vascularity, and elastography values of the lesions were evaluated. Results: Twelve lesions were detected in 12 asymptomatic patients (3 females and 9 males) with a mean age of 4.67 +/- 2.27 years. The most common location of the IET was in posterior part and mid-dle third of thyroid, and the most common appearance on US was a well-defined, ovoid-shaped, and predominantly hypoechoic solid lesion with punctate/linear branching hyperechogenities. The lesions were mostly hypovascular on Doppler US. The mean strain ratio on elastography was found to be 1.10 +/- 0.04. In the follow-up of 7 patients with available information, there was no sig-nificant change in size or appearance of IET on US. Conclusion: IET should be considered in the differential diagnosis of the lesions within the thy-roid. The first step to accurately diagnose an IET is to consider it in the differential diagnosis. In ad-dition to US, strain elastography findings can be used to distinguish IETs from papillary thyroid cancers which can have similar US appearance, and help avoid unnecessary biopsies.