Definition of Branchial cleft cyst :

A branchial cleft cyst is a lump that develops in the neck or just below the collarbone. It is a type of birth defect.

Causes, incidence, and risk factors:

Branchial cleft cysts form during development of the embryo. They occur when tissues in the neck and collarbone area (branchial cleft) fail to develop normally.

The birth defect may appear as open spaces called cleft sinuses, which may develop on one or both sides of the neck. A branchial cleft cyst may form from fluid drained from a sinus. The cyst or sinus can become infected.