Thyroid dysgenesis thyroid gland may be located anywhere along the path of the descent of the thyroid during its embryological development, although it is most commonly located at the base of the tongue, just posterior to the foramen cecum of the tongue. In this location, an aberrant or ectopic thyroid gland is known as a "lingual thyroid". If the thyroid fails to descend to even higher degree, then the resulting final resting point of the thyroid gland may be high in the neck, such as just below the hyoid bone. Parts of ectopic thyroid tissue ("accessory thyroid tissue") can also occur, and
Thyroid disease (lymphocytic infiltration) and destruction (fibrosis) of the gland. Goiter is the general enlargement of the thyroid that can be associated with many thyroid diseases. The main reason this happens is because of increased signaling to the thyroid by way of TSH receptors to try to make it produce more thyroid hormone. This causes increased vascularity and increase in size (hypertrophy) of the gland. In hypothyroid states or iodine deficiency, the body recognizes that it is not producing enough thyroid hormone and starts to produce more TSH to help stimulate the thyroid to produce more thyroid hormone. This stimulation causes the