Midline and Lateral Neck Masses in Children: Thyroglossal and Branchial Cysts on Ultrasound
Role of Ultrasound in Palpable Neck Masses
In the setting of a palpable neck mass, the task of sonography is to determine the origin of the mass by demonstrating its localization, sonographic characteristics, and vascularization (Hagen-Ansert, 2023).
Thyroglossal Cyst (Midline Mass)
The most common congenital cystic anomaly. In 70% of cases, it is located along the midline of the neck anterior to the trachea or within 2 cm of the midline. Embryologically, a narrow hollow tract connects the lobes of the thyroid gland with the floor of the pharynx between the base of the tongue at the level of or below the hyoid bone; normally, this tract should atrophy. When the tract persists, a potential space forms for accumulation of fluid — the cyst can be located at any point along the tract above or below the level of the hyoid bone. It occurs predominantly in children: 90% are detected before age 10 years (Hagen-Ansert, 2023).
According to Griffith (2025), thyroglossal cyst can be located at any point along the tract — from the base of the tongue to the jugular notch of the sternum — and typically presents in childhood as a midline neck mass.
Ultrasound Appearance
The cyst may have typical cyst characteristics, often oval or spherical in shape, located along the midline. It frequently has a more complex appearance and rarely exceeds 2–3 cm (Hagen-Ansert, 2023).
Branchial Cyst of the 2nd Branchial Cleft (Lateral Mass)
A congenital cystic mass located in the lateral part of the neck (Hagen-Ansert, 2023). According to Ahuja (2019), it is an ovoid unilocular mass at the angle of the mandible with characteristic displacement. Sonographically, it may appear as an anechoic cyst, a heterogeneous thick-walled cyst, or a cyst with a pseudosolid echo pattern.
Differential Diagnosis of Lateral Neck Masses (Ahuja, 2019)
| Mass | Ultrasound Features |
|---|---|
| 2nd branchial cyst | Ovoid unilocular mass at the angle of the mandible with characteristic displacement; anechoic cyst, heterogeneous thick-walled cyst, or cyst with pseudosolid pattern |
| Thymic cyst | Unilocular, anechoic, well-defined infrahyoid lateral cyst with thin walls |
| Neck abscess | Thick-walled, poorly defined heterogeneous contents with debris, ± air, with marginal vascularization on Doppler |
Dermoid Cyst
According to Ahuja (2019), on grayscale ultrasound, a heterogeneous cystic mass with internal septa, debris, and dorsal enhancement is identified, located superficially (e.g., in the submental region). A large dermoid containing fat produces heterogeneous echoes and posterior sound attenuation, which can obscure visualization of internal structure. Differentiation between thyroglossal and dermoid cysts is described in specialized sources (Choi et al., Ultrasonography).
Assessment of Associated Lymph Nodes
In evaluating cervical lymph nodes, the Adler classification for vascularization on color Doppler/power Doppler ultrasound is applied: 0 — no blood flow detected; I — single vessel; II — few vessels (1–3 foci), predominantly at the hilum; III — marked vascularization. Hilar type vascularization is characteristic of reactive/benign nodes; peripheral/mixed type is concerning for metastases or lymphoma (Meditrain Consensus, 2026).
Frequently asked questions
Where is thyroglossal cyst typically located?
In 70% of cases along the midline of the neck anterior to the trachea or within 2 cm of the midline; it can be found at any point along the tract above or below the level of the hyoid bone.
What are the typical dimensions of thyroglossal cyst?
Usually oval or spherical in shape, rarely exceeding 2–3 cm; it frequently has a more complex appearance (Hagen-Ansert, 2023).
How does a 2nd branchial cleft cyst appear?
An ovoid unilocular mass at the angle of the mandible with characteristic displacement; it may appear anechoic, heterogeneous thick-walled, or have a pseudosolid echo pattern.
How can a branchial cyst be differentiated from a neck abscess?
An abscess has thick, poorly defined walls, heterogeneous contents with debris, possible air, and marginal vascularization on Doppler, unlike a cyst.
At what age is thyroglossal cyst most commonly detected?
Predominantly in children: 90% are detected before age 10 years (Hagen-Ansert, 2023).