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Arrested development: lingual thyroid gland.

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Most patients with a lingual thyroid gland are asymptomatic, as it rarely manifests clinically with aerodigestive symptoms, malignancy, or endocrine dysfunction. It is therefore usually diagnosed as an incidental finding, more so now with the increased use of cross-sectional imaging in the head and neck region.

We evaluated a 24-year-old Somalian woman who presented with transient right-sided weakness and truncal ataxia with computed tomography (CT) of the head and CT angiography of the neck (figure). They failed to identify any cause for the patients symptoms, but they did demonstrate an incidental finding of a 2.8-cm vascular mass on the posterior aspect of the tongue. The patient had not been aware of the mass. She denied any aerodigestive symptoms and was otherwise well. She did not take any regular medication, and she had no significant medical or surgical history.

Clinical examination failed to visualize the mass through the oropharynx. The patients neck was slender, and her tracheal rings were readily palpable down to the suprasternal notch. Fiberoptic nasoendoscopy confirmed the presence of a midline vascular mass at the base of the tongue; the mass abutted the epiglottis but caused no airway compromise. A diagnosis of lingual thyroid was made.

Ultrasonography of the patients neck revealed the absence of an orthotopic thyroid. Findings on routine blood tests were normal except for a mildly elevated thyroid-stimulating hormone level of 8.0 mU/L (normal; 0.10 to 4.00). The free thyroxine (T4) level was normal at 12.1 pmol/L (normal: 10.0 to 22.0). The patient is currently awaiting an endocrinology opinion to determine whether thyroxine replacement is required.

Embryologically, the thyroid descends from the foramen cecum in the posterior aspect of the tongue to its usual (orthotopic) position anterior to the upper tracheal rings. Derangement of this process can result in ectopic thyroid tissue residing anywhere between the tongue base and the mediastinum. A lingual thyroid is the most common form of thyroid ectopia, representing 90% of all cases. (1)

Most patients with lingual thyroid are asymptomatic and are diagnosed incidentally following a radiologic investigation for another condition of the head and neck. Symptoms such as dysphagia, dysphonia, sleep apnea, and bleeding can occur. (2) As many as one-third of patients are hypothyroid. (3) Lingual thyroid tissue may manifest at any age, but it commonly presents at specific time periods. Puberty and pregnancy are associated with physiologic enlargement of thyroid tissue, and these circumstances can trigger a lingual thyroid to declare itself. (2) Lingual thyroid tissue can become inflamed in response to upper respiratory tract infections. (4)

Patients who are euthyroid rarely require any treatment. Cases associated with hypothyroidism should be managed with oral thyroid hormone replacement therapy. In addition to correcting the patient's underlying hypothyroidism and its associated morbidity, this treatment reduces any physiologic enlargement of the lingual thyroid tissue that might have occurred as a result. (1)

Surgical intervention is rarely required but may be indicated (1) in patients with obstructive symptoms,4 (2) after significant episodes of bleeding, (3) after a rapid increase in the lesion's size, and (4) in cases of suspected malignancy.

The risk of malignant transformation is thought to be the same as the risk of developing cancer within orthotopic thyroid tissue, as reported cases are extremely rare. (5)

References

(1.) Noussios G, Anagnostis P, Goulis DG, et al. Ectopic thyroid tissue: Anatomical, clinical, and surgical implications of a rare entity. Eur J Endocrinol 2011;165(3):375-82.

(2.) Kutlu R, Kalcioglu T, Baysal T, et al. Lingual thyroid: A case report. J Radiol 2002.

(3.) Williams JD, Sclafani AP, Slupchinskij O, Douge C. Evaluation and management of the lingual thyroid gland. Ann Otol Rhinol Laryngol 1996;105(4):312-16.

(4.) Mussak EN, Kacker A. Surgical and medical management of midline ectopic thyroid. Otolaryngol Head Neck Surg 2007;136(6): 870-2.

(5.) Bhojwani KM, Hegde MC, Alva A, Vishwas KV. Papillary carcinoma in a lingual thyroid: An unusual presentation. Ear Nose Throat J 2012;91 (7):289-91.

Mark R. Williams, MRCS(ENT); Vivek Kaushik, FRCS(ORL-HNS)

From the Department of ENT, Stepping Hill Hospital, Poplar Grove, Stockport, Cheshire, U.K.
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Title Annotation:IMAGING CLINIC
Author:Williams, Mark R.; Kaushik, Vivek
Publication:Ear, Nose and Throat Journal
Article Type:Case study
Geographic Code:4EUUK
Date:Jan 1, 2015
Words:690
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