Lingual thyroid: A case report

A 6-year-old female child was referred for thyroid scintigraphy to evaluate the swelling on the posterior part of tongue. The swelling was clinically visible and palpable, red in colour. The thyroid scan was done with ⁹⁹mTco4 and the concentration of radioactivity was seen at the posterior part of the tongue consistent with clinically visible and palpable swelling. No other site of concentration of radioisotope was seen. Hence the diagnosis of the only functional ectopic lingual thyroid was established. Lingual thyroid is a rare congenital anomaly of thyroid gland in which thyroid gland is situated at ectopic location along the course of thyroglossal tract. This is more common in females. Rarely the whole gland is ectopic. Lingual thyroid gland forms a rounded swelling at the back of tongue. It may represent the only thyroid tissue present. It can cause dysphagia, impairment of speech, respiratory obstruction or hemorrhage. Thyroid scan is excellent at not only confirming the diagnosis, but also identifying the presence of any thyroid tissue elsewhere in the neck. Lingual thyroid is best treated by full replacement with thyroxin. Excision or ablation with radioiodine is sometimes necessary. (author)