According to Illingworth's theory, the inclusion of ectopic parotid epithelium in the upper deep cervical lymph nodes leads to the formation of

Branchial cyst • It develops from persistence of precervical sinus, a small depression deep to the second arch that normally disappears during development. • According to Illingworth's theory, inclusion of ectopic parotid epithelium in the upper deep cervical lymph nodes leads to branchial cyst formation. • Though congenital, it often manifests itself between 20-25 yrs. of age, or even later. Presents as a painless swelling in the upper and lateral part of the neck. • It shows a tendency of recurrent infection due to presence of lymphoid tissue in its wall. In that case it becomes painful. • Cholesterol crystals can be demonstrated in the aspirated fluid from a branchial cyst.