Thyroglossal Duct Cysts

A thyroglossal duct cyst is a congenital cyst that sits exactly in the midline of the neck, usually at the level of the hyoid bone. It is the most common congenital cause of a midline neck swelling and is mostly noticed in childhood, but it can also appear in adulthood. Its most distinctive feature is that it moves upwards on swallowing and when the tongue is stuck out.

What is a thyroglossal duct cyst?

At the start of development in the womb, the thyroid gland forms at the base of the tongue and descends to its position in the lower front of the neck. The path it follows during this descent is called the thyroglossal duct, and it normally closes and disappears once development is complete. If part of the duct remains open, a fluid-filled cyst develops at any point between the base of the tongue and the thyroid gland, most often around the hyoid bone. Because the duct passes through or just behind the hyoid bone, the cyst is closely related to this bone.

Symptoms

• A soft, painless lump in the front midline of the neck, usually above the Adam’s apple
• Upward movement of the lump on swallowing and when the tongue is stuck out
• Sudden enlargement, redness and pain of the lump during an upper respiratory tract infection
• If an infected cyst opens onto the skin, a small leaking opening in the midline
• Rarely, a feeling of something catching on swallowing or fullness at the base of the tongue

Diagnosis

On examination, the midline position and movement on swallowing are the typical findings. Ultrasound shows the structure of the cyst and checks whether the thyroid gland is in its normal position; this check matters because, rarely, the tissue thought to be a cyst may be the person’s only functioning thyroid tissue. Magnetic resonance imaging (MRI) or computed tomography (CT) may be requested to see the relationship of the cyst with the hyoid bone and the base of the tongue in detail. If considered necessary, thyroid function is assessed with blood tests; in doubtful cases, a sample may be taken with a fine needle.

Treatment

Thyroglossal duct cysts do not disappear on their own. During an inflamed period, the inflammation is settled first; the permanent treatment is surgery. Removing the cyst alone is not enough; the extension of the duct towards the base of the tongue and the middle portion of the hyoid bone are removed together with the cyst. This method, known as the Sistrunk operation, is the principal way of preventing recurrence, because no remnant of the duct is left behind. The operation is performed under general anaesthesia through a horizontal incision placed in a natural skin crease in the midline of the neck.

What to expect after surgery

Mild pain, swelling and temporary tenderness on swallowing are normal after surgery and subside within a few days. Removal of a small piece of the hyoid bone does not permanently affect speech or swallowing. After a short period of observation, eating begins with soft foods and daily life is resumed. The scar fades over time. When the cyst and duct are removed completely, recurrence is not expected; performing the operation during a period free of inflammation is important in this respect.

When should you see a doctor?

• If you have noticed a persistent lump in the midline of your neck
• If the lump repeatedly enlarges with infections
• If there is redness, pain or discharge over the lump
• If difficulty swallowing or breathing accompanies it