23 Branchial Cleft Cyst

Clinical Presentation

A 4-year-old male presents with a nontender right-sided neck mass.

Figure 23A

Radiologic Findings

Contrast-enhanced axial CT images (Figs. 23A1 and 23A2) depict a well-demarcated, hypodense right-sided unilocular mass effacing the anterior margin of the right sternocleidomastoid muscle. The mass displaces the right internal carotid artery and jugular vein medially. The mass extends inferiorly from the level of the mandibular angle and displaces the right submandibular gland anteriorly. There is a thin enhancing rim, whereas centrally the lesion is nearly isointense with CSF. There is minimal associated lymphadenopathy.

Diagnosis

Second branchial cleft cyst (BCC)

Differential Diagnosis

Pertains to cystic neck masses as follows:

Cystic hygroma
- Typically present at birth (~60%) with 90% seen by 2 years
- Often multilocular and may extend behind sternocleidomastoid muscle
Dermoid cyst
- Congenital midline mass usually present at birth
Thyroglossal duct cyst
- Midline in 75%
- Approximately 65% are below hyoid bone.
- May move upward with sticking tongue out
Necrotic lymph node
- Usually prominent adjacent lymphadenopathy
Hemangioma
- May see flow on Doppler interrogation
Ranula
- Usually in sublingual space
Teratoma
- May see soft tissue components (fat, calcium)
Neural tumor
- Usually primarily solid components
External laryngocele
- Extension from laryngeal ventricle, air or fluid filled

Discussion

Background

Embryologically, the branchial complex consists of six, paired mesodermal arches, which are separated by five clefts lined by endoderm. The fifth and sixth arches are generally rudimentary; however, the first four develop the major structures of the neck, as outlined in Table 23-1. There are three general types of anomalies of the branchial cleft complex. Branchial cleft sinuses are tracts, with or without a cyst, that communicate to gut or skin. Fistulae are residual tracts extending from pharynx to the skin. BCCs are isolated and have no opening to skin or pharynx.

A second BCC can arise anywhere along the embryologic path of the second branchial cleft fistula, which runs from the tonsillar fossa inferiorly along the anterior border of the sternocleidomastoid muscle to the supraclavicular location. There are four types of second BCCs based on their location along this embryologic pathway. Fistulae of second BCCs generally end around the supratonsillar fossa/pillar or directly on tonsil surface and present with recurrent attacks of inflammation.