Endocrine Abstracts

Aim: Thyroid tissue originates from foramen cecum located in the base of the tongue and with embryonal development it descends through thyroglossal duct to its normal location. A total or partial failure in thyroid tissue descending causes ectopic thyroid tissue. One of this ectopic region is lingual region. We presented two case of ectopic thyroid tissue.

Case 1: A 18-year-old female that uses levothyroxine 100 mcg/day for hypothyroidism admitted to endocrinology policlinic. In laboratory investigation TSH and free T₄ values were 2.95 μIU/ml (0.4–4.2 μIU/ml) and 1.25 ng/dl (0.8–2.7 ng/dl) respectively. In thyroid ultrasound there was no thyroid tissue echogenity on normal thyroid location, but there was 13×21×35 mm thyroid echogenity located midline in the superior of thyroid cartilage. Thyroid scintigraphy that performed with 3 mCi Tc^99m pertechnetate confirmed the thyroid tissue in sublingual region that showed in ultrasonography.

Case 2: A 24-year-old women admitted to endocrinology policlinic with puffiness of neck and dyspnea. Laboratory values were as follow: TSH 7.99 uIU/ml, free T4 0.78 ng/dl. In thyroid ultrasound we did not detect thyroid tissue in normal location but 16×21×26 mm nodular tissue was detected in right sublingual region. In Scintigraphy performed with 3 mCi Tc^99m pertechnetate there was no uptake in normal region but there was a focal activity in sublingual region. We prescribed levothyroxine and patient is on follow-up.

Conclusion: Ectopic thyroid tissues may be anywhere in embryonal descending route but rarely seen in mediastinum, heart, esophagus, or diaphragm. The most frequent location of ectopic thyroid tissue is at the base of tongue, accounting for about 90% of the reported cases. Clinical findings are related to size of ectopic tissue and include dysphagia, dysphonia, and dyspnea. In 70 % of patients lingual thyroid tissue is the only thyroid tissue and one third of this patients have hypothyroidism. We suggest screening other possible regions for ectopic thyroid tissue if thyroid tissue is not detected in normal anatomic location.