A thyroglossal cyst is a lump in the midline of the neck. The cyst itself actually originates from thyroid tissue.
The thyroid gland sits in the lower part of the neck, near the midline and just either side. The thyroid gland has a number of important functions, including producing the hormone thyroxine and controlling calcium levels.
Before a baby is born, the thyroid gland actually starts at the back of the tongue. As the baby develops in the womb, the gland gradually moves downwards, to eventually sit in the lower neck.
If this downwards movement is interrupted, part of the gland can get stuck, leading to a lump or a small pit opening onto the skin in (or near) the midline.
Your doctors will likely organise an ultrasound scan to check on the lump and also to make sure that the rest of the thyroid gland is OK.
What problems does a thyroglossal cyst cause?
A thyroglossal cyst may be there without anyone noticing it. Other people notice a small, soft swelling in the front part of your child’s neck, in or near the midline.
Sometimes it causes no problems until it becomes infected, when it swells up and becomes painful. If infected the cyst may increase in size, the overlying skin may appear red and the swelling become tender and painful. If an abscess (collection of infection) develops under the skin it may even start to discharge pus.
Treatment of thyroglossal cyst
Once the diagnosis is made, your doctor will likely discuss surgery to remove the cyst. The operation is called a Sistrunk's procedure. This involves removing the lump itself, plus part of the hyoid bone and some tongue tissue as well. Because we know that the lump started off at the back of the tongue, the surgeon will also probably need to extend surgery up towards the area where the lump would have originated from. The hyoid bone is a bone in the neck just above the voice box, and the thyroglossal cyst often has additional tissue that actually goes through the hyoid bone, hence the need to remove part of the bone. Your body won't miss it though!
On occasion, the surgeon will discover during surgery that the lump actually doesn't appear to be a thyroglossal cyst, in which case the extent of surgery would be modified (usually becoming less extensive than a Sistrunk's pocedure).
After surgery, your child may have a drain placed in the operated area: this is a small plastic tube that removes any bleeding that might develop in the wound. You will probably need to spend a night in hospital.
Risks of surgery include bleeding, infection, and recurrence. Rarely, bruising or injury to nerves for tongue or mouth movement may occur. A scar will be present. This is often larger than you might expect, because the surgery required to remove the lump is quite complex, as you can see from the description above.
If your child presents with an infected thyroglossal duct cyst, it is important to try let the infection settle down with antibiotics in the first instance. If the swelling turns into an abscess, then an operation may be done to allow the pus to drain out. However, the cyst will not be surgically removed during an acute infection because this typically causes problems with long term healing of the wound. A Sistrunk’s procedure to remove the cyst can be performed once the infection has resolved.
Rachael Lawrence MBBS BSc MRCS
Diagram showing the descent
of the thyroid gland before birth