Thyroid scintigraphy in detecting dual ectopic thyroid: a review.

摘要

The thyroid gland is the first endocrine gland to develop during embryogenesis on approximately 24th day of gestation. The developing thyroid is anatomically related to the developing heart, and it is pulled caudally to its definitive location in the anterior neck with the descent of heart. The thyroid completes its descent on reaching anterior to the trachea in the lower neck in the seventh gestational week. The development defects or aberrant migration of the thyroid descent will lead to ectopy of the thyroid. The Foxe 1 mutation is also shown to be associated with molecular pathology of ectopic thyroid in mouse models; however, till date, no known gene for human ectopic thyroid has been demonstrated . An ectopic thyroid gland may occur anywhere along the path of initial descent of the thyroid. The most commonly found ectopic thyroid tissue is at the base of the tongue, i.e. lingual thyroid, which accounts for 90% of the reported cases.