Branchial Cyst

Early in pregnancy, the neck develops from a series of folds called branchial arches. Normally these fuse together completely, but occasionally a small pocket or channel remains, and this is known as a branchial remnant.

A branchial cyst is a fluid-filled remnant that appears as a smooth, painless lump on the side of the neck, in front of the large muscle that runs from behind the ear to the collarbone. Some remnants open onto the skin as a tiny pit that leaks clear fluid (a branchial sinus or fistula). These are present from birth, although a cyst may not become noticeable until later in childhood, often after a cold.

Branchial remnants do not disappear on their own. Because they are lined with tissue that produces fluid, they gradually enlarge and are prone to becoming infected, especially during throat or respiratory infections. An infected cyst becomes red, swollen and tender and may need antibiotics or drainage.

Removal is recommended to prevent repeated infections, which make the eventual operation more difficult, and to confirm the diagnosis. Surgery is planned once any infection has fully settled. Your child's surgeon will usually arrange an ultrasound to confirm the diagnosis and sometimes other imaging to map the full course of a sinus or fistula before surgery.

The operation is performed under a general anaesthetic. Many children go home the same day, while some stay overnight depending on the extent of the surgery.

An incision is made in a natural skin crease of the neck over the lump so that the scar is as discreet as possible. The cyst, together with any tract leading from it, is carefully removed in its entirety, as leaving any lining behind can allow it to re-form. A tract that extends towards the throat may require a second small incision higher in the neck. The wound is closed with dissolving stitches beneath the skin and covered with a dressing. Occasionally a small drain is placed overnight.

Your child may have a sore neck for a few days and simple pain relief is usually sufficient. Eating and drinking can resume as soon as they feel ready.

Keep the wound dry for the first couple of days, after which gentle washing is fine. Some swelling and firmness under the scar is normal and softens over several weeks. Avoid contact sport for about two weeks. Contact the team if there is fever, increasing swelling, redness or discharge from the wound. The wound and laboratory result will be reviewed at a follow-up appointment.