Description

• A congenital, abnormal tract connecting the skin of the neck with an internal structure
• Results from the incomplete closure or development of the branchial arches or associated clefts
• Involves branchial clefts I to IV, which develop in the 4th week of gestation
• System(s) affected: skin/exocrine

Pediatric Considerations
Most occur in the pediatric age group; the second most common congenital neck masses (20–30%) and the most common lateral neck masses (Thyroglossal duct anomalies are the most common overall and midline.) (1)

Epidemiology

• Predominant age: By definition, all branchial cleft fistulae are present at birth; however, they may remain unnoticed for some time.
• Often present when the cyst becomes acutely inflamed or infected
• Branchial cleft cysts may not present until adulthood and are commonly diagnosed in the 3rd and 5th decades of life.
• Predominant sex: male = female

Incidence
Unknown

Prevalence
Unknown

Etiology and Pathophysiology

• Branchial anomalies result from the incomplete obliteration of pharyngeal clefts and pouches during embryogenesis.
• Both respiratory and squamous epithelium (alone or together) may line branchial anomalies.
• Squamous epithelium is found more commonly in cysts.
• Ciliated, columnar epithelium is found more commonly in sinuses and fistulae.
• The first branchial cleft contributes to the external auditory canal, middle ear cavity, mastoid air cells, and eustachian tube. Related fistulae are very rare and tend to be infra- or retroauricular. Preauricular cysts and sinuses are not thought to be of branchial cleft origin:
  • First branchial cleft anomalies enter the external auditory canal and/or occasionally the middle ear.
  • They represent approximately 1–5% of all branchial cleft malformations.
  • Type I anomalies contain ectodermal elements only and course lateral to the facial nerve and parotid gland.
  • Type II anomalies contain ectoderm and mesoderm, coursing medial to the facial nerve often inferior to the angle of the mandible.
• The second branchial cleft forms the hyoid bone and tonsillar fossa. Related fistulas (most common variant) course between the internal and external carotid arteries:
  • Second branchial anomalies represent up to 95% of all branchial cleft lesions. Up to 10% of presentations are bilateral (2).
  • They course close to the glossopharyngeal and hypoglossal nerves, entering the pharynx at the level of supratonsillar fossa.
  • The external opening runs inferior to the angle of the mandible and along anterior border of sternocleidomastoid (SCM) muscle.
  • Second branchial cleft anomalies are subdivided into four subtypes:
    • Type I lesions are anterior to the SCM and do not involve the carotid sheath.
    • Type II lesions are the most common second branchial cleft anomalies, deep to the SCM, and anterior or posterior to the carotid artery.
    • Type III lesions pass between the internal and external carotid arteries and are adjacent to the pharynx.
    • Type IV lesions are medial to the sheath, adjacent to the tonsillar fossa.
• The third and fourth branchial clefts form the parathyroid glands, thymus, and portions of thyroid gland (parafollicular cells):
  • Third branchial cleft anomalies represent approximately 1% of all branchial anomalies. Fourth branchial cleft anomalies are quite rare (<1%).
  • Sinus tracts (also called pyriform sinuses) originate in the pyriform sinus and course adjacent to the thyroid cartilage.
  • Fistulas are rare, usually resulting from recurrent infections and/or repeated surgery.
  • Both third and fourth fistulas should have external ostia on the lower anterior neck. Left-sided lesions are more common than right-sided ones.
  • They are often called pyriform sinus “fistulae,” despite the frequent lack of an external opening to the skin.
  • Those from the third branchial cleft course posterior to carotid artery.
  • Differentiated from second branchial cleft anomalies by the location of their internal opening (external openings should be the same)
  • Presence of thymic tissue does not differentiate between third and fourth branchial cleft anomalies because accessory thymic tissue has been described in the latter (3).

Genetics
10% have family history.

Risk Factors

Positive family history

Commonly Associated Conditions

• Microtia and aural atresia occur with failure of development of the first branchial cleft.
• The rare constellation of second branchial arch anomalies; malformations of the outer, middle, and inner ear associated with sensorineural; mixed or conductive hearing loss, and the absence of renal abnormalities is known as branchiootic syndrome.