A completely ectopic 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.

[3] 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.

[3] Parts of ectopic thyroid tissue ("accessory thyroid tissue") can also occur, and arises from remnants of the thyroglossal duct, and may appear anywhere along its original length.

[3] Accessory thyroid tissue may be functional, but is generally insufficient for normal function if the main thyroid gland is entirely removed.

[3] Lingual thyroid is 4-7 times more common in females, with symptoms developing during puberty, pregnancy or menopause.