Elsevier

Clinical Imaging

Volume 46, November–December 2017, Pages 57-64
Clinical Imaging

Review Article
Thyroglossal duct cysts in children: Sonographic features every radiologist should know and their histopathological correlation

https://doi.org/10.1016/j.clinimag.2017.07.002Get rights and content

Highlights

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    Features highly predictive of thyroglossal duct cyst: presence of fistula, irregular wall, ill-defined margin, internal septum, intralesional flow and solid component.

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    If the features are absent it doesn't rule out the final diagnosis of TGDC, but when present confidently increase the diagnosis of TGDC.

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    The use of these features preoperatively to confirm the diagnosis may assist with the process of obtaining consent, planning surgery and limiting the extent of surgery where possible.

Abstract

Distinguishing between thyroglossal duct cysts (TGDC) and dermoid cysts (DC) sonographically can be challenging. We illustrate the three sonographic features in neck masses in children recently identified as being most suggestive of TGDC (septa, irregular wall and solid elements) and their corresponding histopathology. These three variables form a proposed predictive model for TGDC as a guide to surgical intervention. Pediatric radiologists should be familiar with these key imaging features, as compared with other imaging features described in TGDC also illustrated here, which are less discriminating.

Introduction

Ultrasound (US) is commonly used to assess midline neck masses in children. Even though thyroglossal duct cysts (TGDC) are the most common midline neck masses in children [1], [2], [3], [4], [5], [6], it is important to distinguish TGDC from dermoid cysts (DC) or lymph nodes (LN) in order to plan an appropriate treatment strategy. For example LN in this area are commonly observed or treated with antibiotics whereas DC are simply excised and TGDC are removed via Sistrunk procedure. This involves resecting the entire tract, middle of the hyoid bone and a cuff of tongue musculature. Oyewumi et al. recently described three clinically reliable ultrasound features that were able to discriminate between TGDC and DC [7]. A predictive model was fashioned whereby each variable was scored as 0 or 1, with a total score calculated (septae + irregular wall + solid components = TGDC [or SIST] score). A scoring system whereby 0 = suggestive of DC; 1 = suggestive of TGDC; and ≥ 2 = highly suggestive of TGDC, was proposed.

The purposes of this paper are: 1) to illustrate these key sonographic features to raise awareness of their value for broad clinical application and 2) compare preoperative sonographic features with postoperative pathological specimens from the same patient to demonstrate how US images the tissue in these lesions.

Section snippets

Embryology

The thyroid gland originates at the tuberculum impar in the tongue base at the level of the foramen caecum. At 3 weeks' gestation, a ventral diverticulum develops from the first and second branchial arches and descends in the midline of the neck to the normal location of the thyroid gland [8]. The path of descent is usually anterior to the hyoid bone, but may be posterior to or through the bone [9] (Fig. 1).

The tract usually atrophies and disappears by the tenth week of gestation. Portions of

Ultrasound features of TGDC

Prior studies have described uncomplicated TGDC on ultrasound as being thin-walled anechoic structures [3] and as being heterogeneous with a thick wall if they have been infected or hypoechoic in the presence of hemorrhage [4].

Oyewumi recently identified 7 ultrasound variables that could discriminate between TGDC and DC with high positive predictive value (PPV). The three features that were the most strongly predictive of TGDC were internal septae, irregular wall and presence of solid

Differential diagnosis

Other nodular lesions in the anterior midline neck should be considered in the differential diagnosis because management is not the same for every lesion [16]. The differentiation between a TGDC and dermoid cyst or lymph node can be difficult when the TGDC does not present as an anechoic cyst, thin walled, central and in close relation to the strap muscles. When TGDC presents with these features, a dermoid cyst should not be considered.

Conclusion

US is considered to be the gold standard for studying anterior midline neck masses in children because it is non-invasive, low risk, and provides excellent imaging of internal contents. Differentiating between lymph nodes, DC and TGDC is important clinically, but has not always been successful. Evaluation for internal septae, wall irregularity and solid components may allow for differentiation of TGDC and DC which may ultimately alter surgical management and improve patient care.

Author contributions

First author: Emilio J. Inarejos Clemente

Contribution: study conception and design, selection and compilation of image sample. Drafting of manuscript, subsequent manuscript revisions and final approval of the version to be submitted.

Second author: Modupe Oyewumi

Contribution: drafting of figures and figures legends, subsequent manuscript revisions and final approval of the version to be submitted.

Third author: Evan Probst

Contribution: collection of clinical information, manuscript revisions and

Disclosure

The authors have no conflicts of interest to declare.

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