Branchial cleft cyst
|Branchial arch fistula|
|Classification and external resources|
Fistulography of a right branchial cleft sinus.
|ICD-10||Q18.0 (ILDS Q18.020)|
A branchial cleft cyst is a congenital epithelial cyst that arises on the lateral part of the neck due to failure of obliteration of the second branchial cleft (or failure of fusion of the second and third branchial arches) in embryonic development.
The cyst wall is composed of either squamous or columnar cells with lymphoid infiltrate, often with prominent germinal centers. The cyst may contain granular and keratinaceous cellular debris. Cholesterol crystals may be found in the fluid extracted from a branchial cyst.
- First branchial cleft fistulae typically originate in the angle of the mandible and extend to the external auditory canal. They are often associated with the facial nerve. Rare ~5%.
- Second branchial cleft fistulae are most common (~95%). They are found along the anterior border of the Sternocleidomastoid muscle, pass through the carotid bifurcation and into the tonsillar pillar.
- Third and fourth branchial cleft fistulae are rare. The external opening occurs about 2/3 of the way down the SCM anteriorly, similar to second branchial cleft cysts. The tract ascends along the carotid sheath posteriorly to the internal carotid artery, under the glossopharyngeal nerve, and over the vagus nerve and hypoglossal nerve to open into the piriform sinus.
Most branchial cleft fistulae are asymptomatic, but they may become infected. The cyst, however, usually presents as a smooth, slowly enlarging lateral neck mass that may increase in size after an upper respiratory tract infection. 
Conservative (i.e. no treatment), or surgical excision. As complete surgical excision may be difficult (due to the close proximity of the internal jugular vein and carotid vessels that lie deep to the swelling), they can recur.
- Hong, Chih-ho. Branchial cleft cyst. eMedicine.com. URL: http://www.emedicine.com/derm/topic61.htm. Accessed on: August 24, 2008.
- Shubin, Neil "Your Inner Fish" 2009
- Colman, Rebecca (2008). Toronto Notes. pp. OT33.
- Waldhausen JH (May 2006). "Branchial cleft and arch anomalies in children". Seminars in pediatric surgery 15 (2): 64–9. doi:10.1053/j.sempedsurg.2006.02.002. PMID 16616308.