| Branchial cyst | |
|---|---|
| Other names | Branchial arch fistula Benign cervical lymphoepithelial cyst Pharyngeal arch cyst |
 | |
| Fistulogram (sinogram) of a right branchial cleft sinus. | |
| Specialty | Medical genetics  |
| Symptoms | Painless, firm mass lateral to midline, usually anterior to theSCM, which does not move with swallowing |
| Causes | Family history |
| Differential diagnosis | Vascular anomaly,dermoid cyst,thymic cyst[broken anchor],lymphadenopathy,lymphoma,HPV-related oropharyngeal cancer |
| Treatment | Conservative,surgical excision |
Abranchial cleft cyst or simplybranchial cyst is acyst as a swelling in the upper part of neck anterior tosternocleidomastoid. It can, but does not necessarily, have an opening to the skin surface, called afistula. The cause is usually adevelopmental abnormality arising in the early prenatal period, typically failure of obliteration of the second, third, and fourthbranchial cleft, i.e. failure of fusion of the secondbranchial arches and epicardial ridge in lower part of the neck. Branchial cleft cysts account for almost 20% of neck masses in children.[1] Less commonly, the cysts can develop from the first, third, or fourth clefts, and their location and the location of associated fistulas differs accordingly.
Most branchial cleft cysts present in late childhood or early adulthood as a solitary, painless mass, which went previously unnoticed, that has now becomeinfected (typically after anupper respiratory tract infection). Fistulas, if present, areasymptomatic until infection arises.[2]
Branchial cleft cysts are remnants ofembryonic development and result from a failure of obliteration of one of the branchial clefts, which arehomologous to the structures infish that develop intogills.[3][4]
The cyst wall is composed of squamousepithelium (90%), columnar cells with or withoutcilia, or a mixture of both, with lymphoid infiltrate, often with prominentgerminal centers and few subcapsular lymph sinuses. The cyst is typically surrounded by lymphoid tissue that has attenuated or absent overlying epithelium due to inflammatory changes.[5]
Thediagnosis of branchial cleft cysts is typically done clinically due to their relatively consistent location in the neck, typically anterior to thesternocleidomastoid muscle. For masses presenting inadulthood, the presumption should be amalignancy until proven otherwise, since carcinomas of the tonsil, tongue base and thyroid may all present as cystic masses of the neck.[6] Unlike a thyroglossal duct cyst, when swallowing, the mass should not move up or down.[7]
Four branchial clefts (also called "grooves") form during the development of a human embryo. The first cleft normally develops into theexternal auditory canal,[8] but the remaining three arches are obliterated and have no persistent structures in normal development. Persistence or abnormal formation of these four clefts can all result in branchial cleft cysts which may or may not drain via sinus tracts.
Conservative (i.e. no treatment), orsurgical excision. With surgical excision, recurrence is common, usually due to incomplete excision. Often, the tracts of the cyst will pass near important structures, such as theinternal jugular vein,carotid artery, orfacial nerve, making complete excision impractical due to the high risk of complications.[11]
An alternative and less invasive treatment is ultrasound-guidedsclerotherapy.[12]