The branchial arches represent the embryological precursors of the face, neck and pharynx

The branchial arches represent the embryological precursors of the face, neck and pharynx.

Third and fourth branchial cleft anomalies may appear similar to second branchial cleft anomalies externally with a cutaneous opening in the supraclavicular area; however, internally, they enter the pharynx through the pyriform sinus below the hyoid bone.

Most third branchial cleft cysts present in the posterior cervical space, posterior to the sternocleidomastoid muscle as a painless, fluctuant mass.

An infected third branchial cleft cyst should be considered if a patient presents with an abscess in the posterior triangle of the neck.They are commonly left-sided for reasons that are yet to be established and most often present as a sinus tract coursing from the apex of the pyriform fossa to the upper aspect of the left thyroid lobe. As a result, patients can present with a recurrent abscess in the low anterior neck and/or recurrent suppurative thyroiditis.

There are no pathognomonic clinical or imaging features of branchial arch anomalies; therefore diagnosis is dependent upon the radiologist having a sound knowledge of the types of branchial arch malformations and their typical location.

Branchial arch anomalies represent 20 % of cervical neck masses in children and typically result from incomplete obliteration of branchial clefts with subsequent formation of cysts, fistulae and sinus tracts. Second branchial cleft anomalies represent the most frequent subtype with surgical excision being the most common curative option.