Thyroglossal duct pathology and mimics
Congenital anterior neck masses comprise a rare group of lesions typically diagnosed in childhood. Most commonly, lesions are anomalies of the thyroglossal duct, namely the thyroglossal duct cyst, along with ectopic thyroid tissue. Although usually suspected based on clinical examination, imaging can confirm the diagnosis, assess the extent, and evaluate for associated complications. Imaging characteristics on ultrasound, CT, and MRI may at times be equivocal; differential considerations include branchial cleft cyst, dermoid/epidermoid, laryngocele, thymic cyst, lymphatic malformation, and metastatic disease. Thus, understanding of the embryologic course of thyroid development is crucial with recognition of critical landmarks such as the foramen cecum, hyoid bone, thyroid cartilage, and strap musculature to aid in the diagnosis of an anterior neck mass.
KeywordsThyroglossal duct Ectopic thyroid Neck mass Cystic lesions
Thyroglossal duct cyst is the most common congenital neck mass.
Critical anatomic landmarks of thyroglossal duct anomalies and ectopic thyroid tissue include the foramen cecum at the tongue base, hyoid bone, thyroid cartilage, and strap musculature.
Important differentiating feature of thyroglossal duct cyst is close association to the posterior aspect of the hyoid bone.
Suprahyoid thyroglossal duct cysts are usually midline, while infrahyoid thyroglossal duct cysts may be paramidline.
Orthotopic thyroid tissue is absent in 70–80% of patients with lingual thyroid, and therefore, an important consideration in preoperative planning.
In the evaluation of anterior neck masses in children and young adults, thyroglossal duct anomalies are on top of the differential diagnosis. Subsequent diagnostic imaging with initial ultrasound examination followed by definitive CT and MR examinations assist in diagnosis and assessment of anatomical extent and complications, as well as pretreatment planning. In addition, knowledge of the course of the embryologic thyroid improves diagnostic accuracy. Critical anatomic landmarks of thyroglossal duct anomalies and ectopic thyroid tissue include the foramen cecum at the tongue base, hyoid bone, thyroid cartilage, and strap musculature.
The purpose of this article is to review the common and variant forms of thyroglossal duct anomalies. Anatomy of the embryologic descent of the thyroid gland will first be reviewed, followed by the imaging characteristics of thyroglossal duct cyst and ectopic thyroid tissue. Variant forms and complications of thyroglossal duct cysts will also be reviewed. To strengthen diagnostic accuracy of thyroglossal duct anomalies, similar appearing cystic anterior neck masses will be discussed with focus on key differentiating features.
Anatomy and embryology
Role of imaging
Although benign anterior neck masses such as thyroglossal duct cysts are often diagnosed clinically, the clinical presentation of infected cysts, thyroglossal duct carcinoma, or other pathologic mimics may be indistinguishable, necessitating diagnostic imaging. In children or adults with low clinical suspicion for tumor, imaging evaluation may begin with ultrasound. However, if there are atypical sonographic features (i.e., solid component or abnormal vascularity) or high clinical suspicion for tumor, CT or MR imaging is recommended to document an orthotopic thyroid gland and to evaluate for and characterize the features and extent of neoplastic processes . In selected cases, diffusion-weighted or dynamic contrast-enhanced MR imaging can be performed in evaluation of vascular malformations, abscess, or suspicious cervical lymph nodes .
Thyroglossal duct cyst
If a portion of the thyroglossal duct persists, cystic lesions may arise following cycles of infection and/or inflammation as it is lined with secretory epithelium . Cysts can form anywhere along the course of the duct; however, about 65% of cysts occur at the infrahyoid level . The cyst is histologically composed of epithelial lining of squamous or pseudostratified ciliated columnar epithelium with or without ectopic thyroid gland tissue . As secretions and debris accumulate, suprahyoid cysts can enlarge, push through the floor of the mouth and penetrate down into the anterior neck with resultant symptoms leading to clinical presentation. Thyroglossal duct cysts are the most common non-odontogenic cyst in the neck and most common pediatric cystic neck anomaly and are therefore important to recognize .
Infected thyroglossal duct cyst
Malignancy in a thyroglossal duct cyst
Coexisting carcinoma is rare, occurring in less than 1% of patients and usually arises from thyroid remnants entrapped within the cyst during development. Often these carcinomas are incidentally diagnosed on surgical pathology as the initial disease burden may be microscopic with slow growth. Although thyroglossal duct cysts are anomalies commonly occurring in the pediatric population, coexisting carcinoma usually occurs in patients 40 years of age or older . All subtypes of thyroid carcinoma have been described in thyroglossal duct cysts with the exception of medullary carcinoma due to lack of parafollicular cells in the thyroid anlage. The vast majority of cases represent papillary carcinoma, similar to orthotopic thyroid malignancy. Despite the lack of established predisposing factors, radiation therapy is considered a risk factor along with a female predominance.
Mimics of thyroglossal duct cysts
Distinguishing imaging features of cystic lesions in the anterior neck
Differentiating features of cystic lesions
Thyroglossal duct cyst
Close association with posterior aspect of hyoid
Midline in suprahyoid neck, may be paramidline in infrahyoid neck
Branchial (second) cleft cyst
Located along anteromedial border of the sternocleidomastoid muscle, lateral to the carotid space, and at the posterior margin of the submandibular gland
Beak sign may be present (curved rim of the lesion extending between the internal and external carotid arteries)
Located in subcutaneous tissues, superficial to strap musculature, typically near suprasternal notch
Presence of fat or calcification
May be primarily air-filled or with air-fluid levels due to airway communication
Involvement of laryngeal ventricle
Close association with the carotid sheath, sometimes splaying the carotid artery and jugular vein
Dumbbell or bilobed appearance can be seen with extension into the anterior mediastinum
Multiple, growing masses
Irregular solid and cystic components
Calcifications suggestive of papillary thyroid carcinoma
Fluid-fluid levels from recent hemorrhage
Branchial cleft cysts
Dermoid and epidermoid cysts
Necrotic lymph nodes
Ectopic (lingual) thyroid
Accurate assessment of anterior neck masses requires awareness of the embryological path of thyroid development for recognition of thyroglossal duct anomalies, variants, and complications. Knowledge of differentiating features of other cystic neck masses is important due to different clinical implications.
Both authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- 2.Branstetter B, Weissman J, Kennedy T, Whitaker M (2000) The CT appearance of thyroglossal duct carcinoma. AJNR Am J Neuroradiol 21:1547–1550Google Scholar
- 3.Imhof H, Czerny C, Hörmann M, Krestan C (2004) Tumors and tumor-like lesions of the neck: from childhood to adult. Eur Radiol 14(Suppl 4):L155–L165. https://doi.org/10.1007/s00330-003-2035-0
- 4.Koeller KK, Alamo L, Adair CF, Smirniotopoulos JG (1999) Congenital cystic masses of the neck: radiologic-pathologic correlation. Radiographics 19:121–146Google Scholar
- 5.Nakayama S, Kimachi K, Nakayama K, Ikebe T, Ozeki S (2009) Thyroglossal duct cyst occurring in the floor of the mouth: report of 2 cases. J Oral Maxillofac Surg 67:2690–2693Google Scholar
- 8.Fang WS, Wiggins RH 3rd, Illner A et al (2011) Primary lesions of the root of the tongue. Radiographics 31:1907–1922Google Scholar
- 9.Som PM, Curtin HD (2011) Head and neck imaging, 5th edn. Mosby, St LouisGoogle Scholar
- 10.Sistrunk WE (1920) The surgical treatment of cysts of the thyroglossal tract. Ann Surg 71:121–122Google Scholar
- 11.Ibrahim M, Hammoud K, Maheshwari M, Pandya A (2011) Congenital cystic lesions of the head and neck. Radiology 220:621–630Google Scholar
- 14.Glastonbury CM, Davidson HC, Haller JR,Harnsberger HR (2000) The CT and MR imaging features of carcinoma arising in thyroglossal duct remnants. AJNR Am J Neuroradiol 21:770–774Google Scholar
- 15.Ahuja A, King A, King W, Metreweli C (1999) Thyroglossal duct cysts: sonographic appearance in adults. AJNR Am J Neuroradiol 20:579–582Google Scholar
- 16.Mittal MK, Malik A, Sureka B, Thukral BB (2012) Cystic masses of neck: a pictorial review. Indian J Radiol Imaging 22:334–343Google Scholar
- 19.Fischbein NJ, Noworolski SM, Henry RG, Kaplan MJ, Dillon WP, Nelson SJ (2003) Assessment of metastatic cervical adenopathy using dynamic contrast-enhancing MR imaging. AJNR Am J Neuroradiol 24:301–311Google Scholar
- 20.Holzapfel K, Duetsch S, Fauser C, Eiber M, Rummeny EJ, Gaa J (2009) Value of diffusion-weighted MR imaging in the differentiation between benign and malignant cervical lymph nodes. Eur J Radiol 72:381–387Google Scholar
- 22.van Rijswijk CS, Geirnaerdt MJ, Hogendoorn PC et al (2004) Soft tissue tumors: value of static and dynamic gadopentetate dimeglumine-enhanced MR imaging in prediction of malignancy. Radiology 233:493–502Google Scholar
- 25.Dolezal J, Vizda J, Horacek J, Spitalnikova S (2013) Lingual thyroid: diagnosis using a hybrid of single photon emission computed tomography and standard computed tomography. J Laryngol Otol 127:432–434Google Scholar
- 26.Noussios G, Anagnostis P, Goulis DG, Lappas D, Natsis K (2011) Ectopic thyroid tissue: anatomical, clinical, and surgical implications of a rare entity. Eur J Endocrinol 165:375–382Google Scholar
- 27.Fiaschetti V, Claroni G, Scarano AL, Schillaci O, Floris R (2016) Diagnostic evaluation of a case of lingual thyroid ectopia. Radiol Case Rep 11:165–170Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.