Acoustic Radiation Force Impulse Imaging in the Differential Diagnosis of an Ectopic Intrathyroidal Thymus

Ectopic intrathyroidal thymus is caused by a hesitate in the migration of thymus during embryogenesis and is a rare cause of a nodular intrathyroidal lesion. Nodular thyroid lesions raise the suspicion of malignancy in the pediatric age group. Although rare, ectopic intrathyroidal thymus is usually misdiagnosed as a thyroid nodule and in addition to ultrasonography, further imaging techniques including MRI is performed. Fine needle aspiration biopsy or surgical excision, are also included in the management in thyroid nodules, because of the possibility of a malignancy. Acoustic Radiation Force Impulse-Imaging (ARFI) is a new method determining the tissue elasticity using short duration acoustic pulces and exciting the tissue in the selected region of interest. Acoustic Radiation Force Impulse-Imaging had been used in the differentiation of malign and benign thyroid nodules with or without in combination with gray-scale ultrasonography findings. We here present a case of intrathyroidal ectopic thymus in a 4 year-old boy diagnosed with the use of Acoustic Radiation Force Impulse-Imaging in addition to gray scale and Doppler ultrasonography findings.