Branchial cysts tend to present after the age of 10 years, most commonly in young adulthood when the cyst becomes noticeable or infected.
Pharyngeal cleft 1 forms the EAM
The second pharyngeal arch should extend inferiorly and cover the rest of the clefts (2-4), the space behind the extended 2nd arch is the region of the cervical sinus which should be obliterated
Cervical (branchial) cysts, sinuses or fistulae are formed from remnants of the embryological cervical sinus.
The cyst usually forms from the second cleft which has failed to properly form, the space can fill with fluid - branchial cyst. Can also arise from 1,3,4 cleft but is much more rare
A sinus is a blind ending pouches. A fistula is an abnormal connection between two epithelial surfaces.
A branchial cleft sinus describes when the branchial cyst is connected via a tract to the outer skin surface. There will be a small hole visible in the skin beside the cyst. There may be a noticeable discharge from the sinus.
A branchial pouch sinus describes when the branchial cyst is connected via a tract to the oropharynx.
A branchial fistula describes when there is a tract connecting the oropharynx to the outer skin surface via the branchial cyst.
Sinuses and fistula pose an increased risk of infections in the branchial cyst, as they are a way for pathogens to get in.