A three-year-old girl is brought in due to a swelling on her neck. During the examination, I see a painless, soft swelling in the middle of her neck. The tests show that her thyroid gland is normal, and there is a cystic structure that extends to the hyoid bone through a channel in the middle. We remove the cyst along with the hyoid bone, and the problem is resolved.
I explained the “Thyroglossal duct cyst,” which is the most common congenital cyst in the neck, in the Pediatric Surgeon’s Journal.
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When the embryo is only 4 weeks old, a small protrusion begins to form from the tongue. This small protrusion gradually moves downward along the midline of the neck and settles in the region that is its usual location in the lower part of the neck. Yes, I’m talking about the thyroid gland. This descent path passes just in front of the hyoid bone, which we call the hyoid bone, and rarely it can also pass behind it, but the connection to the hyoid bone is very important for us. After the descent is completed, this descent duct usually disappears around the tenth week. If it doesn’t disappear, cysts develop from these remnants, called thyroglossal duct cysts. “Tiro” means thyroid, “glosso” means tongue. That’s where the name comes from.
These cystic structures, usually located in the midline, are mostly detected in children and teenagers, but about one-third of cases can occur at a later age. Studies on cadavers have found thyroglossal duct cysts in 14 out of 200 adults, 7%.
A mobile, painless, soft mass located in the midline. It can settle anywhere from the base of the tongue to the bottom of the neck. There are also rare case reports where it has settled in unusual places.
The classical information is that it moves in conjunction with the movement of the tongue when swallowing, but try explaining that to a child. They usually start crying the moment you reach out to them…
Anyway, what I want to say is that they are usually noticed due to symptoms resulting from the development of an infection in a lump or cyst in the neck.
Our first preference is always an ultrasound. It allows us to determine if it’s benign or cystic right away. But it usually doesn’t show the connection with the hyoid bone. CT or MRI may be needed for further evaluation. If there is doubt about whether the thyroid gland is properly located, we may also request a scintigraphy. In some cases, fine needle biopsies are also performed, but especially in children, given the low likelihood of cancer and cost-effectiveness analysis, it’s often not done. We always conduct thyroid function tests in all patients.
As you can probably guess, the treatment is to remove the cyst. Why? Because an infection can develop, and because it can contain 1-2% cancer cells.
Infection is very important because even in cysts that haven’t had an infection, the recurrence rate is around 8%, but after an infection, this rate can go up to 40%.
In surgery, we remove the entire cyst, the duct, and, due to the proximity of the duct, the middle of the hyoid bone together. In our language, this procedure is called a Sistrunk operation.
Let me answer the question that may come to your mind right away. Removing the middle of the hyoid bone doesn’t create any problems. Maybe swallowing can be slightly painful for a few days after surgery, that’s all.
In some places, treatments involving injections into the cyst are also mentioned, but it’s important to make sure there is no cancer, and the success rates are lower.
Recently, regular follow-up with ultrasound has also been offered as an alternative for small and non-infected cysts.
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Stay happy,
Prof. Dr. Egemen Eroğlu
August 2023