branchial cyst
Last reviewed 01/2018
This arises from embryonic remnants of the second branchial cleft in the neck. It is most common in young adults where it presents as a smooth swelling in front of the anterior border of the sternomastoid at the junction of its upper and middle thirds. The position is characteristic.
The cyst may enlarge during an upper respiratory tract infection and then persist. In the acute stage, it may be tender. On examination, it is usually fluctuant but does not transilluminate. It does not move on swallowing. Other enlarged lymph nodes are absent.
Treatment is by excision. Care must be taken not to damage the carotid vessels and internal jugular vein which usually lie deep to the swelling. Removal may need to be delayed if the cyst is acutely inflamed because of the risk of creating a branchial fistula.