To help confirm the diagnosis It is important to see the cyst moves upwards when the tongue is protruded. This occurs because a thyroglossal cyst is attached to the thyroglossal tract which attaches to the larynx by the peritracheal fascia. Doctor Sistrunk was born in Tallahassee, Alabama, in He received the degree of Ph. He was intern in the Charity Hospital, New Orleans, from to , was assistant house surgeon in the New Orleans Sanitarium from to , and practiced at New Orleans from to , and at Lake Charles, Louisiana, from to This pathway originates at the junction of the anterior two-thirds and the posterior third of the tongue at its base.
This pathway commences at the foramen caecum, goes anteriorly, and ends at 2nd and 3rd cartilage of the trachea, where the thyroid ends its trajectory and matures. In its trajectory, the thyroglossal duct passes anteriorly to the forming hyoid bone and thyroid cartilage, until it finally reaches its final position, anterolaterally, at the superior portion of the trachea. The primary function of the duct is to function as the pathway for the trajectory of the primordium thyroid gland, before its descent from the base of the tongue, at the foramen caecum, to the 2nd and 3rd cartilages of the trachea.
Thyroid development begins in the 2 to 3 weeks of gestation and starts as a median outgrowth from the primitive pharynx. The thyroid primordium originates at the foramen caecum, which is the junction of the anterior two-thirds and posterior one-third of the tongue.
From this point onwards, the thyroid then descends to the neck, passing anteriorly and closely to the developing hyoid bone and thyroid cartilage, finally reaching its final position in the inferior pre-tracheal neck by the seventh week of gestation. The rest of the duct is, supposedly, expected to obliterate by the tenth week of gestation.
If any part of the thyroglossal duct persists after the tenth week of gestation, a rise in the probability of pathology occurs. The persistence of any portion of the thyroglossal duct becomes the gateway to the formation of the thyroglossal duct cyst.
If given enough development to the pathology, it can even cause thyroglossal duct cyst carcinoma. Depending on whether the developed mass is benign or malignant, treatment should go accordingly. The procedure consists of a neck incision in which we go up the hyoid bone located in the upper neck. The mid-portion of the hyoid bone is then removed along with a small amount of tongue tissue. Axial a and sagittal b contrast-enhanced CT images of the neck demonstrate the close relationship of a thyroglossal duct cyst non-enhancing cystic structure within the midline neck with the hyoid bone arrows.
Paramidline thyroglossal duct cyst. Lingual thyroglossal duct cyst. Sagittal T2-weighted MR image demonstrates a fluid signal lesion at the foramen cecum arrow. Thyroglossal duct cyst containing debris. Note the lack of vascularity within the lesion and posterior through transmission.
During development, the thyroglossal duct wraps inferiorly around the hyoid bone; therefore, a cystic lesion in close association within the hyoid can clue one into the diagnosis Figs. On rare occasions, the duct may become trapped and incorporated into the second and third arch components of the hyoid bone. As such, the Sistrunk resection involves removal of the hyoid body, as well as the entire thyroglossal duct tract and a portion of the tongue base to minimize local recurrence Fig.
Infrahyoid thyroglossal duct cyst. Long axis grayscale ultrasound image shows a midline cyst in contact with and extending posterior to the hyoid bone arrow. Sistrunk procedure. Some thyroglossal duct cysts may not appear as simple thin-walled unilocular lesions.
Presence of internal high attenuation, internal debris, and septations generally correlates with prior infection. In active or recent infection, patients may complain of tenderness at the site of a rapidly growing neck mass.
Subsequent imaging reveals a thick-walled cyst with rim enhancement and inflammatory changes of the surrounding subcutaneous tissues Fig. Internal contents may vary, with higher complexity reflecting proteinaceous debris, which may be seen in acute or remote infection [ 11 ]. In advanced cases, abscess formation can occur Fig. Fistula formation may develop in severe infections with external cyst rupture or recurrence after resection, although congenital fistula in the newborn have been reported related to complete persistence of the thyroglossal tract after birth 7.
Acquired fistulas can be distinguished apart from congenital cases based on later age of presentation late childhood to early adulthood and focal irregularity; focal enlargement of the tract on fistulography may represent the site of a ruptured cyst or prior resection [ 13 ]. Infected thyroglossal duct cyst.
A year-old male presents with several days of fever, as well as a warm anterior neck mass. Long axis ultrasound image with color Doppler reveals a thick-walled hypoechoic structure containing low level echoes with peripheral hyperemia in the paramidline anterior neck. Infected thyroglossal duct cyst with abscess. There is a communicating peripherally enhancing fluid collection along the floor of the mouth, consistent with abscess arrowhead.
Note stranding of the adjacent fat. Note the relative increased thickness of the wall of the infected thyroglossal duct cyst compared to one that is not infected see Fig. 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 [ 14 ].
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. On imaging, commonly described features include enhancing wall nodularity and calcifications within the thyroglossal duct cyst Figs. Calcification is not usually appreciated on MR imaging, requiring a supplementary CT examination [ 4 , 6 ]. Calcifications are a more specific indicator of malignancy than solid components, as the latter can also be seen in inflammatory processes.
Rarely, a purely solid midline or paramidline lesion may be malignant and should be considered when there is associated central FDG avidity or the presence of suspected regional metastatic lymphadenopathy Fig. Fine needle aspiration cytology may be obtained of suspicious solid components to confirm the diagnosis [ 15 ]. Thyroglossal ductal cyst with malignancy. Axial a and coronal b contrast-enhanced CT images of the neck show an irregularly thick-walled thyroglossal duct cyst with enhancing mural nodule arrows.
Resection revealed papillary carcinoma. Thyroglossal duct cyst with malignancy. Axial CT image demonstrates a thyroglossal duct cyst, which is predominantly cystic, but also has soft tissue attenuation arrow and calcifications arrowhead at the posterior aspect.
Malignancy of thyroglossal duct remnant. Pathology proven papillary carcinoma. There are many mimics of thyroglossal duct cysts, and it is important to recognize these as each has different clinical implications. Close attention to the age of presentation, location of the lesion, association with surrounding structures, and internal architecture can clue one into the correct diagnosis Table 1. Branchial cleft cysts are congenital lesions which usually present after upper respiratory infection and most commonly arise from the second branchial cleft.
These typically are located laterally in the anterior neck, adjacent to the anterior surface of the sternocleidomastoid muscle and lateral to the carotid space and posterior to the submandibular gland, often associated with a sinus tract or fistula. A lateral suprahyoid thyroglossal duct cyst can be distinguished by the presence of a medial tail-like component extending into the hyoid bone Fig.
A second branchial cleft cyst may occasionally demonstrate a beak sign; however, the curved rim of the lesion will tend to extend between the internal and external carotid arteries [ 16 , 17 ]. Thyroglossal duct cyst and branchial cleft cyst. Dermoid and epidermoid cysts represent a part of the spectrum of congenital and acquired cystic malformations sharing the common characteristic of a squamous epithelial lining.
Dermoid cysts will be differentiated by internal calcific and fat content Fig. Epidermoid cysts will show diffusion restriction [ 8 ]. Dermoid and epidermoid cysts arise from dermal elements of the first and second branchial arches, and therefore are located at base of tongue and superficially within the subcutaneous tissues of the anterior neck.
In contrast, thyroglossal duct cysts are classically in a deeper location, embedded within strap musculature and in close proximity to the hyoid bone [ 18 ]. Axial non-contrast CT image illustrates a neck mass located anterior to the thyroid cartilage and superficial to the strap muscles.
The lesion demonstrates the same attenuation as adjacent subcutaneous fat. Saccular cysts and laryngoceles are considered congenital dilatations of the saccule of the laryngeal ventricle in the supraglottic larynx. They are classified as internal, external, or mixed based on relationship of saccular dilatation to the thyrohyoid membrane.
Both these and thyroglossal duct cysts can extend through the thyrohyoid membrane; however, thyroglossal duct cysts do not involve the laryngeal ventricle. Additionally, laryngoceles may be fluid-filled, or have air-fluid levels due to airway communication Fig. Internal laryngocele. Axial contrast-enhanced CT image shows a non-enhancing fluid attenuating structure in right paraglottic region with mass effect on false vocal cord arrow.
Thymic cysts are rare cystic lesions arising from the persistent thymopharyngeal duct, which extends from the pyriform sinus to anterior mediastinum. They are located in the lateral infrahyoid neck, predominantly occurring on the left side Fig. They can be distinguished based on the close association with the carotid sheath, sometimes splaying the carotid artery and jugular vein; the classic dumbbell or bilobed appearance can be seen with extension into the anterior mediastinum [ 11 ].
Thymic Cyst.
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