Pathology

1. Branchial cyst
   • Thought to develop because of a failure of fusion of the embryonic second and third branchial arches
   • Alternative hypothesis: acquired condition due to cystic degeneration in cervical lymphatic tissue
2. Cysts lined by squamous epithelium
3. Usually present in young adults in 3rd decade
4. Equally common in males / females

Diagnosis

1. Clinical examination
2. FNA - opalescent fluid containing cholesterol crystals or pus 

Approach

• Examine as for neck examination

Branchial cyst	Branchial fistula

1. Inspect
   • Found in anterior triangle of neck or the upper / middle third of sternocleidomastoid
2. Palpation
   • Smooth firm swelling
   • Ovoid in shape with long axis running forwards and downwards
   • Fluctuant on palpation
   • May be hard and fixed to surrounding structures in the presence of established or recurrent infection
   • Look carefully for the opening of a fistula in this area (fistula runs between tonsillar fossa and anterior border of sternocleidomastoid)
3. Transillumination
   • Opaque on transillumination (due to desquamated epithelial cell contents)

Completion

1. Ask about associated symptoms
   • Pain
   • symptoms of infection
2. Effect of lump on life

Treatment

1. Surgical excision