Lingual thyroid is the most common form of incomplete descent. It forms about 90% of the cases. Submandibular glands, lymph nodes of the neck and trachea or esophagus are uncommon sites of involvement. Ectopic-thyroid tissue in the mediastinum, pericardial sac, heart, breast, duodenum, mesentery of the small intestine, and adrenal gland has also been reported. Thyroid tissue in its normal location is seen in only one-fourth patients with lingual thyroid.[1
] It occurs more frequently in females, with a female to male ratio 4:1; ectopic thyroid is seen at any age but more commonly during childhood, adolescence, and around menopause. This probably occurs when demands for thyroid hormones increase, causing the increase in circulating TSH levels with growth of the ectopic thyroid tissue.[6
The majority of patients with ectopic thyroid are asymptomatic. Patients with lingual thyroid can present with obstructive symptoms as well as hypothyroidism. Hyperthyroidism is a rare presentation in cases of ectopic thyroid gland with few case reports being reported in the literature.[7
In the case report by Abdallah-Matta et al. the patient presented with a nodular lesion in the lingual thyroid with hyperthyroidism. The restoration of the euthyroid status was done with thionamide and then the ectopic gland was surgically removed. In another case report by Kamijo et al., a 68-year-old female patient presented with perspiration, fatigue, and proptosis with periorbital edema. Examination revealed bilateral proptosis. On further investigations including thyroid function tests, neck ultrasound, color Doppler, computerized tomography, 99m Tc thyroid scan and radioiodine uptake study, diagnosis of lingual thyroid with grave's disease and Grave's ophthalmopathy was established. The patient was treated with methimazole 15 mg/day. Regression in the symptoms was noticed. Steroid pulse therapy was given for reducing the periorbital edema.
Literature search showed only a few cases lingual thyroid with hyperthyroidism and all of them were treated with a combination of antithyroid drugs, steroids, and surgery. To our knowledge, this is the first case of lingual thyroid with hyperthyroidism which has been successfully treated with radioiodine alone and followed by thyroid hormone replacement as the patient developed mild hypothyroidism after radioiodine treatment. Radioiodine treatment in this case could solve the hyperthyroid condition as well as the obstructive symptoms associated with a mass lesion at the base of the tongue in one go. Compared to surgery and antithyroid drugs, this treatment modality has shown that this is much simpler, very effective and gave the patient very satisfying result. Although radioiodine treatment even with a dose of 20 mCi warrants close monitoring and admission of the patient in high dose therapy ward for close monitoring.
So this is a rare case of lingual thyroid which presented with complaints of mass effect with hyperthyroidism. Surgery was difficult due to high vascularity and location of swelling making intubation and surgery technically difficult and risky. So the patient was treated with radioiodine with good result. The patient is presently asymptomatic.