ACR Codes: 2.3
A branchial cleft cyst is a developmental abnormality arising from incomplete closure of one of the five branchial apparati (branchial arch, cleft and pouch) between two and seven weeks gestational age. The result is a cyst, sinus or fistula lined with stratified squamous epithelium containing dermal appendages.
Five branchial arches, each with its own artery and nerve, develop into the structures of the head and neck. Developmental anomalies are recognized in the first, second third and fourth branchial clefts. Second branchial cleft anomalies are the most common and are seen in about 90%-95% of cases. They are seen along the anterior sternocleidomastoid muscle superior and lateral to the carotid artery and cranial nerves IX and XII. The cyst may open into the tonsillar fossa. First cleft anomalies (about 8%) are found in proximity to the external auditory canal and are classified based on the presence of any communication with it. Third cleft anomalies are rare. They involve the pyriform sinus and extend posterior to the carotid vessels. Fourth cleft anomalies are very rare, usually left sided, and extend in the mediastinum from the pyriform sinus.
Branchial cleft cysts are bilateral in 2-3% of cases. Cases tend to cluster in families. The cyst or fistula is usually an asymptomatic mass that appears early in life. Infection may occur, especially after upper respiratory infection. Uninflamed cysts are excised under general anesthesia. The recurrence rate is low.
Gills in fish and amphibians develop from primordial structures phylogenetically similar the branchial apparatus. The Greek word for gills is "branchia".
Reference(s): 1. Ballenger, John J. (editor), Snow, James B. (editor), Rowe, L. Chapter 15, Congenital Anomalies of the Head and Neck. Otorhinolaryngology: Head and Neck Surgery.209-210. 1996.
2. Cummings, Charles W. editor, Donegan, J. O. Chapter 86 Congenital Neck Masses. Otolaryngology – Head and Neck Surgery. 1554-1559. 1993.
3. Koeller, Kelly K. Radiologic Pathology (AFIP Lecture Notes) 2003-2004. pp. 939-946.
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