Second Branchial Cleft Cyst

Submitted by Zombor Zoltani, MSIV

 

General Considerations

  • Cystic dilatation of second branchial apparatus
  • 95% of all branchial cleft anomalies arise from second cleft of which 75% are cysts
  • Other anomalies include fistulas or sinuses or combinations of these

Embryology

  • Branchial cleft cysts arise from incomplete obliteration of cervical sinus of His or from buried epithelial cell rests
  • Branchial arches are derived from neural crest cells
  • Arches are separated by five pairs of grooves and pouches

Clinical Findings

  • Typically first appear between 10-40 years of age as painless, compressible, fluctuant, and lateral neck mass
  • Neck mass may be chronic and increase in size
  • Upper respiratory infections may cause mass to become painful, tender, and enlarge
  • Bilateral branchial cleft anomalies occur in 2-3% of cases

Imaging Findings

  • Classically, cyst located at anteromedial border of sternocleidomastoid muscle, lateral to carotid space, and at posterior margin of submandibular gland
  • May occur anywhere along a line from the oropharnygeal tonsillar fossa to the supraclavicular region of neck
  • Beak sign: considered pathognomonic for second branchial cleft cyst
  • Represents focal extension of cyst wall superior to internal carotid artery and external carotid artery bifurcation
  • Diagnosis made with either CT or MR
  • Contrast needed to differentiate cyst from solid mass

CT

  • Well circumscribed homogeneously low density cysts with no discernable or very thin wall
  • Cyst may be unilocular or septated if secondarily infected 

MR

  • T1: Isointense to CSF unless secondarily infected then cyst may be hyperintense due to infectious debris
  • T2: Hyperintense cyst, minimal wall

Ultrasound

  • Anechoic thin walled cyst with posterior acoustic enhancement
  • May be hypoechoic or variably echogenic if infected 

Differential Diagnosis

  • Lymphangioma
  • Thymic cyst
  • Suppurative jugulodigastic node
  • Cystic vagal Schwannoma
  • Cystic malignant adenopathy

Treatment and Prognosis

  • Complete surgical resection is curative if entire cyst removed
  • Inflammation or infection makes surgical resection difficult
  • Some cyst associated with fistulas or tracts are challenging to resect

 

 


Second Branchial Cleft Cyst.
Axial non-contrast MRI images (above) and sagittal contrast-enhanced MRI images below. There is a cystic mass filled with a simple fluid surrounded by a homogeneously enhancing thin-wall in the right neck anteriorly. The cyst is located anterior to the right sternocleidomastoid muscle and inferoposterior to the right parotid gland and is most consistent with a second branchial cleft cyst.
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Harnsberger, Ric H et al. Diagnostic Imaging Head and Neck. Manitoba: Amirsys. 2004.

Koeller Kelly K. et al.  From the Archives of the AFIP: Congenital Cystic Masses of the Neck: Radiologic-Pathologic Correlation. Radiographics. 1999; 19: 121-146.