Branchial cleft cyst
Approximately 95% of branchial cleft cysts arise from a remnant of a
second branchial cleft which has failed to obliterate. They are usually
found at the angle of the mandible along the anterior border of the sternocleidomastoid,
but their location can be variable as the course of the second branchial
cleft extends from the tonsillar fossa down to the supraclavicular region.
They are usually found in young adults. They often present when they become
infected, and at this point they can have the appearance of an abscess.
Like other cystic lesions, they tend to be bright on T2 and dark on T1 weighted
images. If they are infected, they can have an enhancing rim when contrast
is given with T1 weighted imaging.