Abnomalities in the embryologic development and migration of the thyroid gland can result in ectopic thyroid tissue, which may occur on the midline in any position from the base of the tongue to the mediastinum. Although ectopic thyroid may be
asymptomatic, local obstructive, hemorrhagic or other complication may occur. Radinuclide thyroid scan is confirmatory when the diagnosis is suspected. Hypothyroidism is common in lingual thyroid, and thyroid supplementation is generally
required.
In order to evaluate the features of ectopic thyroid, we investigated the scintigraphic findings, thyroid function test and clinical symptoms of 19 patients with ectopid thyroid.
1) The frequency of ectopic thyroid was about 5.3 times more common in female than in male. Then patients were mostly below 30 years old (79%).
2) The frequency of location of ectopic thyroid were as follows: 10 cases in the tongue base, 1 case in suprahyoid, 5 cases in infrahyoid and 3 cases over 2 areas.
3) The thyroid function test was done in 16 cases of the ectopic thyroid patients. The hypothyroidism was detected in 7 cases, subclinical hypothyroidism in 4 cases and normal thyroid function in 5 cases.
4) The rate of hypothyroidism is 90% in the lingual thyroid and 33% in the others. The thyroid dysfunction was related with the location of the ectopic thyroid (p<0.05).
5) The clinical manifestations include a mass in the tongue base, the foreignbody sensation of a throat and a swallowing difficulty in lingual thyroid. The palpable mass was the chief complaint in the others.
6) We prescribed the thyroid hormone to 10 cases with hypothyroidism. The ectopc thyroid was removed in 2 cases with normal thyroid function. The rest is following up through OPD.
We must consider the possibility of the ectopic thyroid and take the thyroid scan when the patient has a mass in the tongue base, the sublingual and the prelaryngeal area. Then we have to check the thyroid function and follow up when the ectopic
thyroid
is diagnosed, because the patient with normal thyroid function can result in the hypothyroidism.
Except these, we must mind of the possibility of occurrence of the cancer in the ectopic thyroid tissue.
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