Branchial cleft cysts arise from the failure of the pharyngobranchial ducts to obliterate during fetal development. They most frequently present in late childhood or early adulthood, when the cysts become infected usually after an upper respiratory tract infection. A branchial cleft cyst appears as a tender, inflammatory mass located at the anterior border of the sternocleidomastoid muscle
Branchial cleft cysts fall into three categories: first, second, and third branchial cleft anomalies.
First Branchial Cleft Anomalies
First branchial cleft anomalies make up less than 1% of all branchiogenic anomalies and usually appear on the face or near the auricle. There are two types of first branchial anomalies, Type I and Type II.
Type I first branchial cleft cysts are duplication anomalies of the external canal and are composed of ectodermally derived tissue. They may pass into the parotid gland and close to the facial nerve.
Type II anomalies may comprise ectodermally and mesodermally derived tissues. These lesions typically present below the angle of the mandible, pass through the parotid gland in close proximity to the facial nerve, and end either inferior to the external auditory canal or into the canal at the bony cartilaginous junction.
Second Branchial Cleft Anomalies
Second branchial cleft anomalies are the most common of the three types. They present as discrete, rounded masses below the angle of the mandible and at the anterior border of the sternocleidomastoid muscle. The potential tract of an associated sinus passes deep to the second arch structures (eg, the external carotid artery and the stylohyoid and digastric muscles) and superficial to the third arch derivatives (eg, the internal carotid artery), opening into the tonsillar fossa.
Third Branchial Cleft Anomalies
Third branchial cleft cysts present anterior to the sternocleidomastoid muscle and lower in the neck than either first or second branchial cleft anomalies. Third branchial cleft cysts are deep to the third arch derivatives (eg, the glossopharyngeal nerve and the internal carotid artery) and superficial to fourth arch derivatives (eg, the vagus nerve). These anomalies end in the pharynx at the thyrohyoid membrane or pyriform sinus.
The management of branchial cleft anomalies is initial control of the infection followed by surgical excision of the cyst and tract. As a general rule, incision and drainage procedures should be avoided; however, they may be necessary for acute abscess treatment before definitive excision. Needle aspiration and decompression can be beneficial in preventing incision and drainage, which increases the difficulty of definitive excision.