Snapshot A 9-year-old child presents with difficulty swallowing and a mass at the base of her tongue along the midline. There is no cervical lymphadenopathy. Introduction Overview Occurs in 1 in 100,000-300,000 people During embryology, the thyroid begins at the foramen cecum (located at the junction between the anterior 2/3's of the tongue and the posterior 1/3) and descends along the thyroglossal duct to its position distally in the neck. The thyroglossal duct then subsequently involutes (persistence leads to thyroglossal duct cysts) The thyroid's descent caudually can arrest at any point along this tract (sublingual, suprahyoid, infrahyoid, or at the level of the hyoid), most commonly at the foramen cecum itself (90%) In 80% it is the only thyroid tissue and surgical removal renders the patient hypothyroid Occurs 4-7 timmes more commonly in females Patients can be asymptomatic or can have symptoms of dysphagia (difficulty swallowing), dysphonia (speech difficulties), dyspnea (shortness of breath), sleep apnea, and/or bleeding from the mass itself Evaluation Thyroid US is needed prior to any surgical intervention to determine if thyroid is present within the neck Thyroid function studies should be performed to determine if the patient is euthyroid or hypothyroid. One third of patients will be hypothyroid. I 123 scanning can be used to determine the function status of the thyroid tissue that is present Treatment Can give thyroid replacement hormone to see if the mass regresses If not, proceed with surgical excision and chronic thyroid hormone replacement Surgery is necessary for masses that are causing significant obstructive symptoms, bleed, or rapidly increase in size Rests of papillary thyroid carcinoma have been found in lingual thyroid tissue and malignancy is important to consider as part of a differential especially if there is cervical adenopathy