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
Computed tomography of the thyroid hyperparathyroidism. Ectopic parathyroid adenoma is rare. The third and fourth pharyngeal pouches represent the embryological origin of the parathyroid tissues, and ectopic parathyroid adenoma can ultimately develop anywhere along their migration course. In a large retrospective study of patients with primary hyperparathyroidism, PA was detected in the intra-thyroid location in 0.7 % of cases. In another retrospective analysis of 202 patients with ectopic PA, intra-thyroidal location was found in 18 % of the cases. Intra-thyroid parathyroid adenomas mimic thyroid nodules in CT scans and may even show uptake on a thyroid iodine scan. Correlation with laboratory workup, including measurement of