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Second branchial cleft cyst

contributed by Dr Frank Gaillard on May 2, 2008

System: Head & Neck

A second branchial cleft cyst is a cystic dilatation of remnant of the 2nd branchial apparatus, and along with 2nd branchial fistulae and sinuses accounts for 95% of all branchial cleft anomalies.

Demographics and clinical presentation

Although a congenital abnormality, they tend to present in early adulthood (10 - 40 years of age) often after minor trauma on infection. Second branchial cleft sinus or  fistulas on the other hand present earlier.

Typically second branchial cleft cysts present as a rounded swelling just below angle of mandible, anterior to sternocleidomastoid (although the position is variable - see classification below). 

The cyst is typically filled with mucoid material, is well circumscribed and other than presenting as a swelling, is asymptomatic. If infected however, then surrounding stranding and skin changes are evident.

Location and classification

Cysts can occur anywhere along the course of the second branchial apparatus, from the pharyngeal wall to the skin, as it passes laterally and inferiorly between the ICA and ECA.

Radiographic features

CT
  • rounded, sharply circumscribed
  • fluid density centrally
  • thin wall
  • extension of the cyst wall between the ICA and ECA just above the carotid bifurcation (sometimes referred to as the notch sign) is said to be 'pathognomonic'.
Ultrasound
  • sharply demarkated
  • posterior acoustic enhancement : 70% *
  • imperceptible walls : 82%
  • echogenicity is variable
    • anechoic : 41%
    • homogeneously hypoechoic with internal debris : 24%
    • pseudosolid : 12%
    • heterogeneous : 23%

* figures according to Ahuja et al, 2000

Differential diagnoses