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Dual ectopic lingual and sublingual thyroid gland is an extraordinarily rare condition. We present 1 patient with subclinical hypothyroidism. The clinical examination revealed that the thyroid gland was not palpable in its usual cervical location, whereas ultrasonography confirmed an empty thyroid bed without any ectopic thyroid tissue in the rest of the neck. The final diagnosis of dual ectopic lingual and sublingual thyroid was established by ultrasound examination through the mouth floor and confirmed by scintigraphy and CT thereafter.

Ectopic thyroid tissue (ETT) refers to all cases in which the thyroid gland is present at a location other than its usual site. The prevalence of ETT is approximately 1 per 100,000 to 300,000 persons and is reported to occur in 1 of 4000 to 8000 patients with thyroid disease. Multiple ectopia of the thyroid is extremely rare, with fewer than 35 cases published in literature to date. We report a 4-year-old girl with euthyroid and dual ectopia of thyroid without orthotopic thyroid gland. The role of hybrid SPECT/CT in the localization of the sites of ETT is also highlighted.

A 49-year-old man with a clinical diagnosis of Graves' disease was referred for a thyroid scan and radioactive ablation of the gland. Tc-99m pertechnetate scan revealed a diffuse toxic goiter and radiotracer concentration in the thyroglossal duct. He was given 10 mCi of I-131 orally as treatment of thyrotoxicosis. Repeat scanning of the anterior neck 2 days later revealed concentration of radioiodine in the diffusely enlarged gland and the thyroglossal duct as found on the Tc-99m pertechnetate scan, thus confirming the presence of functioning thyroid tissue in the thyroglossal duct.

The authors report a case of hemiagenesis of the left thyroid lobe indicated on Tc-99m pertechnetate scan and later confirmed on ultrasonography. The patient was clinically hypothyroid with a right-sided goiter. The cytopathologic diagnosis was made by fine-needle aspiration cytologic analysis, which indicated chronic lymphocytic thyroiditis in the right lobe of the thyroid gland. Later the patient's condition was stabilized with thyroxine replacement therapy. The association of hemiagenesis of the thyroid with chronic lymphocytic thyroiditis has not been reported in the literature.

Thyroid hemiagenesis is a rare congenital anomaly in which one thyroid lobe fails to develop. Tc-99m pertechnetate scintigraphy and ultrasonography can be used to visualize this anomaly. The authors evaluated four cases with Tc-99m pertechnetate scintigraphy and ultrasonography and confirmed thyroid hemiagenesis. In one case, a Tc-99m MIBI scan excluded the suppresssion of the contralateral thyroid lobe. Tc-99m MIBI can be used to confirm the diagnosis of thyroid hemiagenesis.

Two sisters who presented with midline neck masses proved to be biochemically hypothyroid. Thyroid scintigraphy supplemented with perchlorate discharge testing showed lingual thyroid glands and ruled out the expected autosomal recessive organification defect. The related literature is reviewed.

A case of thyroid hemiagenesis discovered incidentally in a patient presenting with a thyroglossal duct cyst is reported. Thyroid embryology is briefly reviewed. Various characteristics of thyroid hemiagenesis and thyroglossal duct cysts are explored.

I-123 thyroid scintigrams performed in 349 patients were evaluated with a focus on specific thyroid gland vestiges, namely a pyramidal lobe or a thyroglossal duct. The detection of these vestiges in patients with hyperthyroidiam is indicative of autoimmune hyperthyroidism. In Graves' disease, stimulating thyrotropin (TSH) receptor antibodies cause a significantly more frequent appearance of vestiges of the thyroglossal tract. In contrast, disseminated autonomously functioning thyroid nodules rarely show a pyramidal lobe. The frequency of pyramidal lobe visualization in patients with Graves' disease differed significantly from the frequency in patients with multifocal or disseminated autonomously functioning nodules. In euthyroidism patients, the vestiges may be indicative of the diagnosis of iodine deficiency with or without latent primary hypothyroidism. In thyroid scintigraphy, the pyramidal lobe and the thyroglossal duct can be visualized more easily using I-123 instead of Tc-99m sodium pertechnetate.

Thyroid scintigraphy was performed in 69 consecutive infants with permanent primary congenital hypothyroidism (CH) detected by systematic neonatal thyroid screening using a rectilinear scanner or a gamma camera 15 minutes after the intravenous injection of 250 microCi Tc-99m sodium pertechnetate, immediately after the infants were fed. Immobilization of the infant in a supine position with the neck in hyperextension was achieved by a vacuum cushion without any sedation. Thyroid scintigraphy showed thyroid ectopia in 43 of the 69 CH infants, thyroid agenesis in 19, and goiter in the last 7 infants, respectively. The images were easily interpretable in all cases, even in very small ectopic glands in the lingual area, as there was no interference with extra-thyroidal uptake of the tracer, especially by the salivary glands. Our experience indicates that thyroid scintigraphy in the CH newborns can be performed immediately at the time of diagnosis of CH without technical difficulties. As thyroid scintigraphy is the only procedure allowing the distinction between thyroid agenesis and ectopia, and as the neurointellectual prognosis might be lower in the former than in the latter situation, thyroid scintigraphy in CH newborns contributes not only to the diagnosis but also the prognosis of the disorder.

Tc-99m pertechnetate thyroid angiography was performed on 62 patients who had unilateral thyroid enlargement and no radionuclide uptake in the contralateral lobe in an attempt to differentiate suppressed thyroid tissue from thyroidal hemiagenesis. In 55 cases of toxic, autonomous functioning thyroid nodules, the suppressed contralateral lobe was unequivocally demonstrated, the flow study showing tracer coursing through this tissue in the sequential arterial images. No arterial flow was demonstrable on the rapid sequence imaging in the agenetic lobe in seven patients who had thyroidal hemiagenesis. Radionuclide thyroid angiography appears a safe, simple, and accurate one-step study for distinguishing between suppressed thyroid tissue and thyroid hemiagenesis and precludes the requirement for additional studies, such as the thyrotropin stimulation test and Tl-201 scintigraphy.

The scintigraphic findings in a 2-year-old boy with both a lingual thyroid and ectopic thyroid tissue in the neck are presented. One day following excision of the neck mass, no functioning thyroid tissue was seen. However, one month later, the lingual gland was well visualized. The possible reason for this is discussed.

A practical approach to the hyperthyroid patient with a single lobe visualized on thyroid scintigraphy, and its impact on therapy is discussed. An illustrative case is also presented.