Background
Branchial cleft cysts are congenital epithelial cysts, which arise on the lateral part of the neck from a failure of obliteration of the second branchial cleft in embryonic development. [1, 2]
Phylogenetically, the branchial apparatus is related to gill slits. In fish and amphibians, these structures are responsible for the development of the gills, hence the name branchial (branchia is Greek for gills).
Pathophysiology
At the fourth week of embryonic life, the development of 4 branchial (or pharyngeal) clefts results in 5 ridges known as the branchial (or pharyngeal) arches, which contribute to the formation of various structures of the head, the neck, and the thorax. The second arch grows caudally and, ultimately, covers the third and fourth arches. The buried clefts become ectoderm-lined cavities, which normally involute around week 7 of development. If a portion of the cleft fails to involute completely, the entrapped remnant forms an epithelium-lined cyst with or without a sinus tract to the overlying skin. [3, 4, 5, 6]
Etiology
The branchial cleft cyst is a congenital lesion formed by incomplete involution of branchial cleft structures during embryonic development.
Epidemiology
Frequency
The exact incidence of branchial cleft cysts in the US population is unknown. [1] Branchial cleft cysts are the most common congenital cause of a neck mass. An estimated 2-3% of cases are bilateral. A tendency exists for cases to cluster in families. [7]
Race
No ethnic predilection has been reported for branchial cleft cysts. [1]
Sex
No sexual predilection is recognized for branchial cleft cysts. [1]
Age
Branchial cleft cysts are congenital in nature, but they may not present clinically until later in life, usually by early adulthood.
Prognosis
Many branchial cleft cysts are asymptomatic. They may become tender, enlarged, or inflamed, or they may develop abscesses, especially during periods of upper respiratory tract infection, due to the lymphoid tissue located beneath the epithelium. Spontaneous rupture of an abscessed branchial cleft cyst may result in a purulent draining sinus to the skin or the pharynx.
Depending on the size and the anatomical extension of the mass, local symptoms, such as dysphagia, dysphonia, dyspnea, and stridor, may occur.
Following surgical excision of branchial cleft cysts, recurrence is uncommon, with a risk estimated at 3%, unless previous surgery or recurrent infection has occurred, in which case, it may be as high as 20%.
Patient Education
Patients should be reassured that branchial cleft cysts are benign.
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First branchial cleft cyst, type II. Contrast-enhanced axial computed tomography scan at the level of the hyoid bone reveals an ill-defined, nonenhancing, water attenuation mass (m) posterior to the right submandibular gland (g).
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Second branchial cleft cyst. Contrast-enhanced axial computed tomography scan at the level of the hyoid bone reveals a large, well-defined, nonenhancing, water attenuation mass (m) on the anterior border of the left sternocleidomastoid muscle(s).
