Thyroglossal Duct Cyst


What is a Thyroglossal Duct Cyst?

Thyroglossal Duct Cyst is a common type of congenital cyst affecting the neck area. The pocket of the cyst is filled with fluid. The cysts manifest in form of round, firm neck masses within the midline upper neck. The cyst may move when you swallow or stick out the tongue.

Thyroglossal Duct Cyst picture 1

While children with this kind of cyst may be asymptomatic, they will usually complain of feeling tenderness to palpation.

When infected, most of the cysts tend to be red, tender, and increase in their size. Occasionally, there may be spontaneous drainage. Despite these symptoms, rarely do these cysts cause difficult in swallowing or even breathing. 6

Causes

Thyroglossal duct cyst is considered a cystic remnant occurring on the tract or route that thyroid cells take at time of fetal development usually from the base of tongue to the middle or lower neck, which is the postnatal location.

Normally, remains of the tract wipe out during the first trimester, however, in the event that the cells of the tract persist, it could result in a midline cystic remnant that is referred to as thyroglossal duct cyst.

A point to mention here is that thyroglossal cysts can be found anywhere within the thyroglossal duct, but are commonly found below or at the level of hyoid bone, within the upper neck. The cells of thyroglossal duct may secrete mucus, which makes the cyst to gradually grow. 6

Thyroglossal Duct Cyst picture 2

Location of Thyroglossal duct cyst

Thyroid gland in Fetus

During the developmental part of the fetus, the thyroid gland is found in a different location where it later migrates to the usual place.

Initially, thyroid gland is found at bottom of the fetus’s tongue. And early in the life of the fetus, it moves from the tongue’s bottom area and pushes downward to be stationed at the base of the neck.

When the gland is migrating, sometimes it may drag some of the pharynx lining with it. This may result in formation of a cyst at the thyroid’s base along the migration route. This way, a thyroglossal duct cyst is created.

A major risk associated with thyroglossal duct cyst is occurrence of an infection. Considering that the mouth tends to have a lot of bacteria, these may cause an infection on the cyst.

Mostly, a thyroglossal cyst appears in the ages between 2 and 10 years and is found in both boys and girls at equal predominance.

Thyroglossal Duct Cyst picture 3

Symptoms

A child with thyroglossal duct cyst will show various symptoms. However, each child might have varying symptoms and they include:

  • Tenderness, swelling, redness of the mass, especially if it has been infected
  • A soft, round, small mass forming in the front of the neck at the midline
  • There may be a small opening occurring in the skin just near the mass, where drainage of mucus or fluid inside the cyst may be happening
  • With very enlarged cysts, they may cause difficult with breathing and swallowing.

Diagnosis

It is important to understand that the symptoms of thyroglossal duct cysts could resemble those of other neck masses or even other medical problems. Therefore, it is essential that a proper diagnosis be done. Diagnosis involves the following:

Physical exam

Sometimes, diagnosis of this condition occurs when a doctor is examining a child of upper respiratory infections. A doctor may do an examination of the cyst by touching it or looking at its location. The mass tends to move upwards after extending the tongue or when you swallow something because the thyroglossal ducts connects at the tongue’s base. A doctor will need to determine if the cyst has thyroid tissue. The doctor may order other examinations and testing procedures.

Blood tests

With these tests, they are intended to assess how thyroid is functioning

Thyroid scans

Using radioactive iodine, it may help show abnormalities within the thyroid. A radioactive metallic element known as technetium may be used instead of iodine.

Ultrasound

This imaging technique makes use of high frequency sound wave to create images of organs, tissues, and blood vessels. The images are displayed in a computer and help evaluate the muscles surrounding the mass. Usually, the ultrasound imaging is used to view how internal organs are functioning and to assess blood flow within vessels.

Fine needle aspiration

In this procedure, cells are removed from cysts so that further diagnosis is conducted.

Treatment

While the cyst may be benign, a patient may need to have it removed, especially if he or she is experiencing difficulties with swallowing or breathing.

It may also be removed if it has been infected. Again, even without these symptoms, it may be necessary to remove the cyst in order to prevent chances of an infection occurring or having carcinoma.

Sometimes, the protrusion may look unsightly in which case a cosmetic reason may underlie the need for removal of the cyst. Time in time, a doctor may order thyroid scans or thyroid function studies so see that the thyroid tissue is functioning normally and is in its usual location.

Surgery/Removal

thyroglossal duct cyst Surgery or Removal

Surgery to remove thyroglossal duct cyst includes options like the Sistrunk procedure, suture-guided transhyoid pharyngotomy, en bloc central neck dissection, or Koempel’s supra-hyoid procedure. In removing this cyst, cystectomy is considered inadequate.

Sistrunk procedure involves surgical resection. This resection is done on the central part of hyoid bone and the tissue from the midline part found between foramen cecum and hyoid bone. The incision is not only done on the cyst itself but also the pathway tract and branches. This procedure generally involves the below steps:

  • An incision
  • A resection of cyst as well as the hyoid bone
  • Draining and closing the opening

Different versions of Sistrunk surgical procedure are available and they include:

Classic

This involves excision of the central part of the hyoid together with the cyst. It also entails removal of the core of tongue muscle above the hyoid about one-eighth in diameter. It may also include the mucosa.

Modified

This involves a dissection done through the base of the tongue instead of through the mucosa. This procedure is recommended for both primary treatments as well as revision treatments.

Hyoid cartilage division

Where there is immature ossification of hyoid, a monopolar Bovie electrocauterization procedure may be used to divide the non-fused cartilage part.

In general, Sistrunk procedure is considered a safer option with 95 percent cure rate as well as 95 to 100 percent survival rate.

Complications

Infection

If left untreated for a long time or in situations where the thyroglossal duct cyst has not been suspected, an infection could occur. To determine if there is an infection, a doctor or a patient may look at the location of the cyst in which case there may be a major rim enhancement occurring and it’s located at lower area of the hyoid bone.

There may be soft tissue swelling, especially along the airways and a patient may have trouble or obstruction when swallowing because the cyst has enlarged rapidly.

Thyroglossal fistula

Sometimes, the cyst may rupture suddenly leading to a draining sinus, which is also referred to as thyroglossal fistula. This fistula may also develop in case the removal of the cyst wasn’t completed fully.

You or your doctor may notice there is fistula when bleeding occurs in the neck area resulting in swelling and ejection of fluid around the wound where the cyst had been removed.

Thyroglossal duct cyst carcinoma

When there is cancer manifesting in the thyroglossal duct, it may be termed as thyroglossal duct cyst carcinoma. The tumors may occur due to ectopic thyroid tissue present in the cyst.

Pictures

thyroglossal duct cyst anatomy location

thyroglossal duct cyst Gross Anatomy

Reference List

  1. Thyroglossal Cyst. https://en.wikipedia.org/wiki/Thyroglossal_cyst
  2. Pediatric Thyroglossal Duct Cyst. https://childrensnational.org/choose-childrens/conditions-and-treatments/ear-nose-throat/thyroglossal-duct-cyst
  3. Thyroglossal Duct Cyst Imaging. http://emedicine.medscape.com/article/1346365-overview
  4. https://radiopaedia.org/articles/thyroglossal-duct-cyst
  5. Thyroglossal Duct Cyst in Children. https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02068
  6. Thyroglossal Duct Cyst. https://medicine.yale.edu
  7. http://www.childrenshospital.org/conditions-and-treatments/conditions/thyroglossal-duct-cyst

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