Persistent thyroglossal duct with a retrohyoid cyst containing pearl-like structures revealed by cadaveric dissection

The thyroglossal duct (TGD) is an embryonic fibrous tract that guides the descent of the thyroid gland from the tongue base to its definitive pretracheal location. Cadaveric studies reporting persistent TGD associated with cyst formation are rare. During routine dissection of the thyroid gland in an elderly female cadaver, we identified a persistent TGD arising from the left thyroid lobe and extending superiorly toward the left lateral border of the thyroid cartilage. A midsagittal section of the cervicocephalic region revealed superior extension of the TGD coursing posterior to the hyoid bone and terminating inferior to the tongue, where it formed a multilocular cyst containing nodular, pearl-like structures, consistent with a thyroglossal duct cyst (TGDC). To our knowledge, this is the first cadaveric report demonstrating an intact persistent TGD with a retrohyoid/infralingual course and intimately associated TGDC containing pearl-like nodules. This case highlights the retrohyoid space as a potential site of occult TGDCs with surgical and radiological relevance. It also underscores the importance of targeted anatomical dissection, including midsagittal sectioning, in identifying retrohyoid TGDCs that may remain clinically silent and anatomically hidden.