Lingual Thyroid Ectopia: Diagnostic SPECT/CT Imaging and Radioactive Iodine Treatment.

BACKGROUND: Lingual thyroid is a rare abnormality of thyroid development that is usually treated conservatively with levothyroxine replacement. Rarely, it becomes large enough to cause obstructive symptoms in the oral cavity, requiring definitive treatment. PATIENT FINDINGS: This study reports on three patients with lingual thyroid treated with radioactive iodine-131 ((131)I) with successful radioablation of their ectopic thyroid tissues. Measurement of 24-hour radioactive iodine uptake within thyroidal tissues and hybrid single-photon emission computed tomography/computed tomography imaging using either iodine-123 or technetium-99m pertechnetate scans were performed in all patients demonstrating the location and size of lingual thyroid and absence of an orthotopic thyroid gland. SUMMARY: The aim of this study was to describe nonsurgical management of obstructive lingual thyroid tissue with (131)I therapy for lingual thyroid radioablation. Patients were prepared with a low-iodine diet and levothyroxine withdrawal prior to radioablation for optimizing (131)I uptake in ectopic thyroid tissues. Hybrid single-photon emission computed tomography/computed tomography measurement of anatomic size of lingual thyroid tissue and radioactive iodine uptake guided the selection of therapeutic doses, resulting in administration of 10.7, 17.5, and 15.4 mCi of (131)I, respectively. There were no post-therapy complications, and clinical follow-up demonstrated resolution of obstructive oropharyngeal symptoms. CONCLUSIONS: Ectopic lingual thyroid tissue is rarely associated with obstructive oropharyngeal symptoms due to progressive enlargement. Radioiodine therapy with (131)I is an effective treatment modality for ablation of ectopic thyroid tissue as an alternative to surgery.

[Lingual thyroid].

Lingual thyroid is a rare congenital malformation that occurs more frequently in the female population. It occurs because of the error in transcriptional factors, the key for the normal differentiation of thyrocyte, so the thyroid gland tissue does not descend normally down the thyroglossal duct to the final position in the neck. Due to that, it can entirely or partially remain at the base of the tongue. This is the most frequent localization of the ectopic tissue while it can remain in the sublingual, suprahyoid and infrahyoid area as well. This disease can be diagnosed in the asymptomatic phase, as well as in the phase of compensatory and manifest hypothyroidism. In the ectopic thyroid gland, all diseases of the thyroid gland can occur as in the usual localization in the neck. The authors show a 6-year old patient, who had a routine medical examination for the inflamed throat, during which a vascular tumefaction was discovered at the base of the tongue. A cyst at the base of the tongue was suspected, but additional examination showed that it was an ectopic thyroid tissue marked as a lingual thyroid gland. Diagnosis of this disease starts with the laboratory analysis of the thyroid status. The next step involves scintigraphy of the thyroid gland with technetium-pertechnetate (99mTc) or radioactive iodine (123I). The therapy of the compensatory hypothyroidism is suppressive therapy with levothyroxine and in the manifest hypothyroidism it is hormone substitution therapy with levothyroxine. Although there are recommended age-related daily doses, they should not be accepted as final, but rather prescribed according to the individual thyroid status.