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Clinical Problem Solving: Radiology
August 2007

Radiology Quiz Case 2—Diagnosis

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Copyright 2007 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2007

Arch Otolaryngol Head Neck Surg. 2007;133(8):837-838. doi:10.1001/archotol.133.8.837

Lingual thyroid, or thyroid ectopia, is a rare anomaly, with a female predominance and a reported incidence ranging from 1:3000 and 1:100 000 (usual age at onset, 6-74 years).1 It results from the failure of the thyroglossal duct to migrate from the foramen cecum of the tongue to the normal prelaryngeal location.2,3 The normal descent of the thyroid gland occurs between weeks 3 and 7 of embryogenesis.4 Maldescent of the thyroid gland most commonly results when the ectopic thyroid tissue is located at the base of the tongue in the area of the foramen cecum, between the circumvallate papillae and the epiglottis.5 While 90% of thyroid ectopia involves the tongue, the presence of ectopic thyroid tissue has also been reported along the thyroglossal tract of descent, involving the esophagus, mediastinum, heart, diaphragm, and peripharyngeal sites.6 This lingual thyroid tissue is the only functioning gland in more than 70% of individuals. Approximately 33% of patients have clinical hypothyroidism, which is usually associated with increased physiologic and metabolic demands. There is a high incidence of thyroid disease within family members of patients with lingual thyroid. Multiple factors, including genetics, toxins, infections, and immunologic or autoimmune abnormalities such as maternal antithyroid immunoglobulins causing arrest of thyroid gland descent and impaired gland functioning, have been postulated to interfere with organogenesis and steps of normal thyroid development.6,7

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