9365 Now You See Me: The Case Of The Ectopic Thyroid

Abstract Disclosure: S.I. Suarez: None. S.K. Majumdar: None. Introduction: Lingual thyroid refers to ectopic thyroid tissue located at the base of the tongue or within the thyroglossal tract secondary to failed descent to its usual site (1). Ninety percent of ectopic thyroid glands are found at the base of the tongue and can occur in 1 in every 100,000 patients (2, 3). Clinical presentations commonly relate to obstruction of the oropharynx, and patients may experience dysphagia or throat fullness/discomfort (1). We present a case of lingual thyroid presenting as dysphagia and progressive hypothyroidism. Case: A 38-year-old woman with a history of HLD and hypothyroidism was referred for evaluation of ectopic thyroid tissue. She presented to her provider for concerns of dysphagia, neck swelling, and excessive hair thinning/loss. She had a recent increase in levothyroxine dose from 112 to 125 mcg after a TSH of 20.4 (0.27 to 4.2 uIU/mL). Repeat tests showed a TSH of 29.4 and a free T4 level of 0.79 (0.8 to 1.7 ng/dL). She denied use of thyrotoxic medications, any radiation or surgeries to head or neck, personal or family history of autoimmune disorders. Thyroid was nonpalpable on exam. A thyroid US 5 years prior showed a 15 x 5 x 5 mm right lobe and 12 x 8 x 5 mm left lobe. CT scan of soft tissue of neck with contrast showed a 14 x 13 x 15 mm hyperintense nodular lesion midline along the anterior glossoepiglottic fold at the foramen cecum, with an 8 x 11 x 8 mm hyperintense nodular lesion at midline abutting the anterior body of the hyoid bone, and no thyroid tissue in the expected thyroid bed, findings consistent with ectopic thyroid tissue along the expected thyroglossal duct. Furthermore, an I-123 scan with SPECT confirmed the ectopic thyroid tissue. What was thought to be thyroid lobes on previous thyroid US was likely paratracheal fat. Levothyroxine was increased to 137 mcg per day with improvement at 2 months (TSH 10.4, Free T4 0.91). Adjusting levothyroxine replacement was the primary intervention, given that elevated TSH may result in hypertrophy of lingual thyroid tissue resulting in dysphagia, particularly if there is no mass or suspicion of cancer on imaging. Conclusion Hypothyroidism presenting with dysphagia in the absence of goiter, previous thyroid surgery, or detectable thyroid tissue should warrant consideration of ectopic thyroid tissue and initial therapy should be directed towards normalizing TSH in conjunction with excluding malignant causes. References: 1. Randolph, G. W., & Kamani D. V. (2023). Thyroglossal duct cyst, thyroglossal duct cyst cancer, and ectopic thyroid. UpToDate. Retrieved February 13, 2024, from 2. Patil, Y. S., Rajashekhar R. P. (2015). Lingual Thyroid: A Case Series of Six Lingual Thyroid with Incidence and Different Treatment Modalities. International Journal of Head and Neck Surgery (IJHNS). 10.5005/jp-journals-10001-1234. 3. Kumar, L. K., Kurien, N. M. (2015). Lingual Thyroid. Annals of Maxillofacial Surgery. DOI: 10.4103/2231-0746.161103 Presentation: 6/1/2024