A branchial cleft cyst is a congenital cyst that appears on the side of the neck, usually just below the angle of the jaw. It results from incomplete closure of the branchial clefts, which form the face and neck during development in the womb. These anomalies usually show in childhood; a cyst with no opening onto the skin may go unnoticed until adolescence or adulthood, when it swells after an upper respiratory tract infection.1
What is a branchial cleft cyst?
In early development, the neck region contains branchial clefts, which resemble the gill slits of fish. Normally these clefts fuse and close. If part of one remains open, three different structures may form:1,2
- Cyst: A closed, fluid-filled sac with no opening to the outside.
- Sinus: A blind-ended channel opening only onto the skin or only into the throat.
- Fistula: A channel open at both ends, onto the skin and into the throat.
Most cysts originate from the second branchial cleft and sit in the upper-middle part of the neck along the front edge of the large neck muscle (sternocleidomastoid). Less commonly, there are types seen in front of and around the ear, or in the lower part of the neck.2,3
Symptoms
- A soft, mobile lump on one side of the neck that mostly does not hurt1,2
- Enlargement of the lump during a cold or throat infection, followed by some shrinkage
- Redness, tenderness and pain when it becomes inflamed
- If a sinus or fistula is present, a clear or sticky leak from a small opening in the skin of the neck1
- With large cysts, a feeling of pressure during swallowing
Diagnosis
On examination, the position and consistency of the cyst give typical findings. Ultrasound shows the cystic structure of the lump and its contents. Magnetic resonance imaging (MRI) or computed tomography (CT) may be requested to see the depth of the cyst, whether it has a tract extending towards the throat, and its relationship with the large neck vessels. In adults, a fine-needle aspiration biopsy may be needed to distinguish a cystic mass on the side of the neck from other causes.1,3,4
Treatment
Branchial cleft cysts do not disappear on their own. During an inflamed period, the inflammation is treated first and any collected pus is drained if necessary; however, these measures give only temporary relief. The treatment is surgical removal of the cyst, and of its tract if present, in one piece. The operation is performed under general anaesthesia through an incision that follows the natural creases of the neck. If the tract extends as far as the throat, an approach through the mouth may also be needed to clear the remnant completely. Protecting the vessels and nerves along the course of the cyst is the most important stage of the operation; injury to these structures is a rare complication.1,3
What to expect after surgery
Mild pain and swelling in the neck are normal after surgery and usually subside within a few days. Most people go home after a short period of observation; because the incision is placed in a neck crease, the scar usually fades over time. When the cyst and tract are removed completely, recurrence becomes less likely; remnants left behind, on the other hand, can lead to renewed swelling. For this reason, the operation should be planned for a quiet period when there is no inflammation.1
When should you see a doctor?
- If there is a lump on the side of your neck that has not gone away for a few weeks
- If the lump repeatedly enlarges with infections
- If you have noticed a small leaking opening in the skin of the neck
- If the lump is hardening, growing quickly or making swallowing difficult
Frequently asked questions
What is a branchial cleft cyst?
A branchial cleft cyst is a congenital cyst that appears on the side of the neck, usually just below the angle of the jaw. It results from incomplete closure of the branchial clefts during development in the womb, and may take the form of a closed sac (cyst), a channel open at one end (sinus) or a channel open at both ends (fistula).
How is a branchial cleft cyst treated?
The treatment is surgical removal of the cyst, and of its tract if present, in one piece; the operation is performed under general anaesthesia through an incision that follows the natural creases of the neck. During an inflamed period, the inflammation is treated first and the operation is planned for a period free of inflammation.
Why does a branchial cleft cyst appear in adulthood?
The cyst has been present since birth but stays small and silent. It is usually noticed when it swells during a throat infection, which is why some people receive the diagnosis only in adolescence or adulthood.
Can a cyst be watched without surgery?
Small cysts that cause no complaints can be observed for a while; however, the cyst does not disappear on its own and may swell again with every infection. The treatment is surgical removal.
Does the cyst come back after surgery?
When the cyst and its tract are removed in one piece, recurrence becomes less likely. Recurrence usually results from remnants left behind or from surgery performed during an inflamed period.
References
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Holt AC, Lofgren DH, Hohman MH, Shermetaro C. Branchial cleft anomalies. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [cited 2026 Oct 5]. Available from: ncbi.nlm.nih.gov ↩
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Adams A, Mankad K, Offiah C, Childs L. Branchial cleft anomalies: a pictorial review of embryological development and spectrum of imaging findings. Insights Imaging. 2016;7(1):69-76. doi:10.1007/s13244-015-0454-5 ↩
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Fanous A, Morcrette G, Fabre M, Couloigner V, Galmiche-Rolland L. Diagnostic approach to congenital cystic masses of the neck from a clinical and pathological perspective. Dermatopathology (Basel). 2021;8(3):342-358. doi:10.3390/dermatopathology8030039 ↩
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Pynnonen MA, Gillespie MB, Roman B, Rosenfeld RM, Tunkel DE, Bontempo L, et al. Clinical practice guideline: evaluation of the neck mass in adults. Otolaryngol Head Neck Surg. 2017;157(2 Suppl):S1-S30. doi:10.1177/0194599817722550 ↩
This page is general information. Decisions about diagnosis and treatment are made for you personally, and only after an examination. If you have symptoms, see a doctor.