Lingual thyroid: a clinical case.
Lingual thyroid is an abnormal formation appearing as the result of a deficient descent during embryological development of the thyroid gland through the thyroglossal duct to its normal pretracheal location. The lesion consists of a tumor mass of thyroid tissue located at the base of the tongue, in the region of the foramen caecum linguae. The size can vary from a few millimeters to several centimeters in diameter. More than 400 cases of lingual thyroid have been documented in the literature to date. Lingual thyroid has been identified in 10% of the tongues examined in some autopsy series. Its identification is of great significance, since it may constitute the only functional thyroid tissue in the body, and may inadvertently be destroyed as a result of histological biopsy procedures. The present study presents a clinical case of lingual thyroid in a 17-year-old female.