About 20% of cervical masses in children.

Localization

 cervical region
 parotid
 mediastinum

TYpes

 first branchial cleft cyst

• First branchial cleft cysts are divided into type I and type II. Type I cysts are located near the external auditory canal. Most commonly, they are inferior and posterior to the tragus (base of the ear), but they may also be in the parotid gland or at the angle of the mandible. They may be difficult to distinguish from a solid parotid mass on clinical examination. Type II cysts are associated with the submandibular gland or found in the anterior triangle of the neck.

 second branchial cleft cyst

• The second branchial cleft accounts for 95% of branchial anomalies. Most frequently, these cysts are identified along the anterior border of the upper third of the sternocleidomastoid muscle, adjacent to the muscle. However, these cysts may present anywhere along the course of a second branchial fistula, which proceeds from the skin of the lateral neck, between the internal and external carotid arteries, and into the palatine tonsil. Therefore, second branchial cleft cyst is in the differential of a parapharyngeal mass.

 third branchial cleft cyst

• Third branchial cleft cysts are rare. A third branchial fistula extends from the same skin location as a second branchial fistula (recall that the clefts merge during development); however, a third branchial fistula courses posterior to the carotid arteries and pierces the thyrohyoid membrane to enter the larynx. Third branchial cleft cysts occur anywhere along that course (eg, inside the larynx), but are characteristically located deep to the sternocleidomastoid muscle.

 fourth branchial cleft cyst

• Fourth branchial cleft cysts are extremely rare. A fourth branchial fistula arises from the lateral neck and parallels the course of the recurrent laryngeal nerve (around the aorta on the left and around the subclavian artery on the right), terminating in the pyriform sinus; therefore, fourth branchial cleft cysts arise in various locations, including the mediastinum.

Complications

 squamous cell carcinoma arising in a branchial cleft cyst

Synopsis

 1 to 4 cm of diameter
 squamous or ciliated columnar epithelium
 lymphoid nodules beneath the surface epithelium

Differential diagnosis

 thymic cyst
 thyroglossal cyst

See also

 branchial clefts