Pediatric lingual ectopic thyroid: two contrasting cases and a narrative literature review.

Objective: To report two contrasting pediatric cases of lingual ectopic thyroid, one involving misdiagnosis and inadvertent excision and the other involving correct diagnosis and conservative treatment, and to summarize the diagnostic and therapeutic lessons through a narrative literature review. Methods: The clinical data of two children with ectopic thyroid were retrospectively reviewed. Case 1 was a 2-year- and 11-month-old girl with a mass at the base of the tongue that was misdiagnosed as a thyroglossal duct cyst and surgically excised. Case 2 was a 9-year-old girl who presented with a foreign-body sensation in the pharynx and was diagnosed with ectopic thyroid after systematic evaluation and treated conservatively. This report was designed as a two-case report/small case series with a narrative literature review. Relevant English-language literature on pediatric ectopic thyroid, lingual thyroid, radionuclide scintigraphy, conservative treatment, surgery, and radioiodine therapy was reviewed to support the discussion of diagnosis and management. Results: In Case 1, preoperative ultrasonography and computed tomography (CT) suggested a thyroglossal duct cyst. Thyroid function testing and radionuclide scintigraphy were not performed, and erroneous excision of the lesion resulted in overt hypothyroidism requiring long-term oral levothyroxine sodium replacement therapy. Radionuclide scintigraphy was not performed because nuclear medicine examination was unavailable at our institution. In Case 2, cervical ultrasonography, thyroid function testing, and contrast-enhanced CT confirmed ectopic thyroid at the base of the tongue with hypothyroidism. Radionuclide scintigraphy was also not performed because of the same institutional limitation. After oral levothyroxine sodium treatment, thyroid function returned to normal and symptoms were markedly relieved. In both patients, no normally located thyroid gland was identified in the neck, indicating ectopic thyroid without eutopic thyroid tissue. Conclusion: Ectopic thyroid should be considered before excision of pediatric tongue-base or anterior midline neck masses, especially when a normally located thyroid gland is not clearly identified. Thyroid function testing and cervical ultrasonography are appropriate initial evaluations. CT or MRI may be used when anatomical detail is required, when the diagnosis is uncertain, or when surgery is being considered. Radionuclide scintigraphy should be considered to confirm functional thyroid tissue and determine whether the ectopic thyroid represents the only functioning thyroid tissue. Treatment should be individualized, with priority given to preservation of thyroid function.