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Radiology Quiz Case 1: Diagnosis

Radiology Quiz Case 1: Diagnosis Diagnosis: Total ectopic lingual thyroid Lingual thyroid is a rare clinical entity that occurs because of a congenital anomaly of thyroidal development and migration. The reported incidence ranges from 1:100 000 to 1:300 000, with a slight female predominance.1,2 The thyroid gland typically descends from the foramen cecum to its normal pretracheal position between weeks 3 and 7 of embryological development.3 The presence of the ectopic thyroid tissue has been reported along the thyroglossal tract of descent in other midline locations of the neck as well as in other rare sites such as the esophagus, trachea, mediastinum, heart, diaphragm, and parapharyngeal spaces.4 However, the lingual thyroid is the most common presentation of ectopic thyroid gland.2,5 The lingual thyroid is the only functional thyroid gland in the body in 75% of these cases,6 most of which are asymptomatic and usually incidentally found on a routine ear, nose, and throat examination. It is clinically symptomatic, while glandular hypertrophy occurs in response to the rise in thyroid-stimulating hormone levels that is generated by an increase in metabolic demand for thyroid hormone, eg, puberty, pregnancy, trauma, infection, and menopause. Symptoms may include a lump in the throat, dysphagia, dysphonia, dyspnea, and, rarely, ulceration or bleeding. Approximately 33% of patients with a lingual thyroid have clinical hypothyroidism.7 On ear, nose, and throat examination, a lingual thyroid may demonstrate a raised tumor at the midline of the tongue base, between the circumvallate papillae and the epiglottis. The color ranges from pink to blue, and the surface may vary from smooth to irregular. For patients in whom a lingual thyroid is clinically suspected, a thorough examination of the thyroid gland at the anterior aspect of the neck is crucial, because most cases reveal an absence of functional thyroid tissue in the expected cervical position.8 The differential diagnosis of the tongue base tumor includes thyroglossal duct cyst, benign minor salivary gland tumor, hemangioma, lymphangioma, teratoma, and even malignant neoplasms. Malignant transformation of a lingual thyroid is exceptionally rare.9 Either computed tomography or MRI could facilitate the final diagnosis of lingual thyroid. Computed tomography often reveals a well-defined, high-density tongue base tumor before the adminstration of a contrast medium; MRI may demonstrate increased signal intensity of the tumor on both T1- and T2-weighted scans. Furthermore, the absence of a orthotopic thyroid gland, as shown by either imaging modality, can establish the diagnosis of a total ectopic lingual thyroid. Technetium 99m radionuclide scanning may confirm the diagnosis by showing increased activity at the base of the tongue and not in the typical location of the thyroid gland.6 However, not all lingual thyroid tissue is functional, so the absence of uptake at the base of the tongue does not exclude the diagnosis. Although computed tomography can locate the ectopic lingual thyroid, the iodinated contrast medium, if used, may delay the utility of radioactive thyroid scintigraphy for approximately 2 months because of the thyroid uptake of iodinated contrast. In this case, the axial precontrast T1-weighted MRI of the head and neck revealed a 28 × 29-mm, well-circumscribed, protuding, oval tumor of low-signal intensity at the base of the tongue (Figure 2). All T1-weighted contrast-enhanced fat-suppressed MRIs failed to demonstrate the thyroid gland at its normal position in the anterior aspect of the neck (Figures 3 and 4). Based on the MRI findings, the diagnosis of a total ectopic lingual thyroid was made. The results of thyroid function tests, including serum thyrotropin and thyroxine levels, were within normal limits. The patient successfully received a surgical reduction of the tongue base tumor via a transoral approach. An ectopic lingual thyroid was pathologically confirmed. During the 9-month follow-up period in outpatient clinics, the patient was symptom-free and the residual ectopic lingual thyroid was stable in size. View LargeDownload Figure 2. View LargeDownload Figure 3. View LargeDownload Figure 4. Thyroid function tests to determine the function of the lingual thyroid are important for treatment strategy. An asymptomatic euthyroid patient does not necessarily require specific treatment but may need long-term follow-up for possible complications and malignant transformation. The principal treatment of symptomatic lingual thyroids is thyroid replacement therapy. Patients who develop compressive symptoms or airway compromise require surgical treatment. Radioablation with iodine 131 is a therapeutic modality for patients who are unsuitable for surgical intervention.6 Return to Quiz Case. References 1. Ulug T, Ulubil SA, Alagol F. Dual ectopic thyroid: report of a case. J Laryngol Otol. 2003;117(7):574-57612901819PubMedGoogle ScholarCrossref 2. Toso A, Colombani F, Averono G, Aluffi P, Pia F. Lingual thyroid causing dysphagia and dyspnoea: case reports and review of the literature. Acta Otorhinolaryngol Ital. 2009;29(4):213-21720161880PubMedGoogle Scholar 3. Winslow CP, Weisberger EC. Lingual thyroid and neoplastic change: a review of the literature and description of a case. Otolaryngol Head Neck Surg. 1997;117(6):S100-S1029419116PubMedGoogle ScholarCrossref 4. Williams JD, Sclafani AP, Slupchinskij O, Douge C. Evaluation and management of the lingual thyroid gland. Ann Otol Rhinol Laryngol. 1996;105(4):312-3168604896PubMedGoogle Scholar 5. Kaplan EL. Thyroid and parathyroid. In: Schwartz SI, Shires GT, Spencer FC, eds. Principles of Surgery. 5th ed. New York, NY: McGraw-Hill Co; 1989:1614-1616 6. Wong RJ, Cunningham MJ, Curtin HD. Cervical ectopic thyroid. Am J Otolaryngol. 1998;19(6):397-4009839916PubMedGoogle ScholarCrossref 7. Grossman A, Olonovski D, Barenboim E. Hypothyroidism caused by a nonvisible lingual thyroid. Head Neck. 2004;26(11):995-99815508119PubMedGoogle ScholarCrossref 8. Baik SH, Choi JH, Lee HM. Dual ectopic thyroid. Eur Arch Otorhinolaryngol. 2002;259(2):105-10711954930PubMedGoogle ScholarCrossref 9. Beil CM, Keberle M. Oral and oropharyngeal tumors. Eur J Radiol. 2008;66(3):448-45918457933PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology - Head & Neck Surgery American Medical Association

Radiology Quiz Case 1: Diagnosis

Archives of Otolaryngology - Head & Neck Surgery , Volume 138 (8) – Aug 1, 2012

Radiology Quiz Case 1: Diagnosis

Abstract

Diagnosis: Total ectopic lingual thyroid Lingual thyroid is a rare clinical entity that occurs because of a congenital anomaly of thyroidal development and migration. The reported incidence ranges from 1:100 000 to 1:300 000, with a slight female predominance.1,2 The thyroid gland typically descends from the foramen cecum to its normal pretracheal position between weeks 3 and 7 of embryological development.3 The presence of the ectopic thyroid tissue has been reported along the thyroglossal...
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Publisher
American Medical Association
Copyright
Copyright © 2012 American Medical Association. All Rights Reserved.
ISSN
0886-4470
eISSN
1538-361X
DOI
10.1001/archotol.138.8.772
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Abstract

Diagnosis: Total ectopic lingual thyroid Lingual thyroid is a rare clinical entity that occurs because of a congenital anomaly of thyroidal development and migration. The reported incidence ranges from 1:100 000 to 1:300 000, with a slight female predominance.1,2 The thyroid gland typically descends from the foramen cecum to its normal pretracheal position between weeks 3 and 7 of embryological development.3 The presence of the ectopic thyroid tissue has been reported along the thyroglossal tract of descent in other midline locations of the neck as well as in other rare sites such as the esophagus, trachea, mediastinum, heart, diaphragm, and parapharyngeal spaces.4 However, the lingual thyroid is the most common presentation of ectopic thyroid gland.2,5 The lingual thyroid is the only functional thyroid gland in the body in 75% of these cases,6 most of which are asymptomatic and usually incidentally found on a routine ear, nose, and throat examination. It is clinically symptomatic, while glandular hypertrophy occurs in response to the rise in thyroid-stimulating hormone levels that is generated by an increase in metabolic demand for thyroid hormone, eg, puberty, pregnancy, trauma, infection, and menopause. Symptoms may include a lump in the throat, dysphagia, dysphonia, dyspnea, and, rarely, ulceration or bleeding. Approximately 33% of patients with a lingual thyroid have clinical hypothyroidism.7 On ear, nose, and throat examination, a lingual thyroid may demonstrate a raised tumor at the midline of the tongue base, between the circumvallate papillae and the epiglottis. The color ranges from pink to blue, and the surface may vary from smooth to irregular. For patients in whom a lingual thyroid is clinically suspected, a thorough examination of the thyroid gland at the anterior aspect of the neck is crucial, because most cases reveal an absence of functional thyroid tissue in the expected cervical position.8 The differential diagnosis of the tongue base tumor includes thyroglossal duct cyst, benign minor salivary gland tumor, hemangioma, lymphangioma, teratoma, and even malignant neoplasms. Malignant transformation of a lingual thyroid is exceptionally rare.9 Either computed tomography or MRI could facilitate the final diagnosis of lingual thyroid. Computed tomography often reveals a well-defined, high-density tongue base tumor before the adminstration of a contrast medium; MRI may demonstrate increased signal intensity of the tumor on both T1- and T2-weighted scans. Furthermore, the absence of a orthotopic thyroid gland, as shown by either imaging modality, can establish the diagnosis of a total ectopic lingual thyroid. Technetium 99m radionuclide scanning may confirm the diagnosis by showing increased activity at the base of the tongue and not in the typical location of the thyroid gland.6 However, not all lingual thyroid tissue is functional, so the absence of uptake at the base of the tongue does not exclude the diagnosis. Although computed tomography can locate the ectopic lingual thyroid, the iodinated contrast medium, if used, may delay the utility of radioactive thyroid scintigraphy for approximately 2 months because of the thyroid uptake of iodinated contrast. In this case, the axial precontrast T1-weighted MRI of the head and neck revealed a 28 × 29-mm, well-circumscribed, protuding, oval tumor of low-signal intensity at the base of the tongue (Figure 2). All T1-weighted contrast-enhanced fat-suppressed MRIs failed to demonstrate the thyroid gland at its normal position in the anterior aspect of the neck (Figures 3 and 4). Based on the MRI findings, the diagnosis of a total ectopic lingual thyroid was made. The results of thyroid function tests, including serum thyrotropin and thyroxine levels, were within normal limits. The patient successfully received a surgical reduction of the tongue base tumor via a transoral approach. An ectopic lingual thyroid was pathologically confirmed. During the 9-month follow-up period in outpatient clinics, the patient was symptom-free and the residual ectopic lingual thyroid was stable in size. View LargeDownload Figure 2. View LargeDownload Figure 3. View LargeDownload Figure 4. Thyroid function tests to determine the function of the lingual thyroid are important for treatment strategy. An asymptomatic euthyroid patient does not necessarily require specific treatment but may need long-term follow-up for possible complications and malignant transformation. The principal treatment of symptomatic lingual thyroids is thyroid replacement therapy. Patients who develop compressive symptoms or airway compromise require surgical treatment. Radioablation with iodine 131 is a therapeutic modality for patients who are unsuitable for surgical intervention.6 Return to Quiz Case. References 1. Ulug T, Ulubil SA, Alagol F. Dual ectopic thyroid: report of a case. J Laryngol Otol. 2003;117(7):574-57612901819PubMedGoogle ScholarCrossref 2. Toso A, Colombani F, Averono G, Aluffi P, Pia F. Lingual thyroid causing dysphagia and dyspnoea: case reports and review of the literature. Acta Otorhinolaryngol Ital. 2009;29(4):213-21720161880PubMedGoogle Scholar 3. Winslow CP, Weisberger EC. Lingual thyroid and neoplastic change: a review of the literature and description of a case. Otolaryngol Head Neck Surg. 1997;117(6):S100-S1029419116PubMedGoogle ScholarCrossref 4. Williams JD, Sclafani AP, Slupchinskij O, Douge C. Evaluation and management of the lingual thyroid gland. Ann Otol Rhinol Laryngol. 1996;105(4):312-3168604896PubMedGoogle Scholar 5. Kaplan EL. Thyroid and parathyroid. In: Schwartz SI, Shires GT, Spencer FC, eds. Principles of Surgery. 5th ed. New York, NY: McGraw-Hill Co; 1989:1614-1616 6. Wong RJ, Cunningham MJ, Curtin HD. Cervical ectopic thyroid. Am J Otolaryngol. 1998;19(6):397-4009839916PubMedGoogle ScholarCrossref 7. Grossman A, Olonovski D, Barenboim E. Hypothyroidism caused by a nonvisible lingual thyroid. Head Neck. 2004;26(11):995-99815508119PubMedGoogle ScholarCrossref 8. Baik SH, Choi JH, Lee HM. Dual ectopic thyroid. Eur Arch Otorhinolaryngol. 2002;259(2):105-10711954930PubMedGoogle ScholarCrossref 9. Beil CM, Keberle M. Oral and oropharyngeal tumors. Eur J Radiol. 2008;66(3):448-45918457933PubMedGoogle ScholarCrossref

Journal

Archives of Otolaryngology - Head & Neck SurgeryAmerican Medical Association

Published: Aug 1, 2012

Keywords: radiology specialty,lingual thyroid

References