Retropharyngeal Ectopic Thyroid Found Histologically in Late-Term Fetuses: A Case Report With an Embryological Study

During ascent of the hypoglossal nerve and nodosa ganglion, the trabecular thyroid seemed to descend along the anterior aspect of these nerve elements. Therefore, the nerve(s) might swipe and cut a trabecula to separate the fragment from the main lobes, resulting in the retropharyngeal ET.