Thyroglossal Duct Cyst and Sistrunk Procedure to Remove It

by , last modified on 4/13/21.

tgd

Rarely, there is a midline neck mass that may develop out of the blue whether in a child or in an adult. It may or may not be tender.

If this sounds like you, see if the following occurs while you are "holding on" to the neck mass.

  • Stick your tongue in and out and see if the mass moves up and down
  • Swallow and see if the mass moves up and down

If the answer is yes, you probably have a thyroglossal duct cyst (TGD).

If the area is tender, the TGD cyst is infected. Sometimes it can be so infected that it can abscess and rupture to the skin where it drains purulent fluid.

TGD is a congenital remnant of thyroid development during fetal growth. In the fetus, the thyroid gland actually forms in the back of the tongue in an area called the foramen cecum. As the fetus develops, the thyroid gland travels from the tongue and settles in the bottom of the neck overlying the windpipe where it remains after birth through adulthood.

The tract the thyroid follows from the tongue to the base of the neck should normally obliterate, but... sometimes it doesn't leaving a potential space for fluid to collect causing a cyst formation. This cyst formation can occur ANYWHERE along the tract from the tongue to the neck. However, it most often seems to occur around the hyoid bone, whether above or more commonly below it (suprahyoid or infrahyoid location).

In the side-profile diagram below, the dotted line in green denotes the tract and the blue circles the common locations for TGD cyst formation.

cartoon

It is not uncommon that the cyst is still tethered to the tract that goes through the hyoid bone and up into the tongue. That's why it moves wtih tongue protrusion as well as swallow.

Workup

A CT scan of the neck is obtained to completely characterize the TGD cyst physically. Particular attention is also made to see if the thyroid gland is present as sometimes, the TGD cyst IS the only functioning thyroid gland present. If there's any doubt or concern about thyroid function, a nuclear thyroid scan can be obtained to localize all functioning thyroid tissue.

A needle biopsy can also be obtained for thyroid tissue presence to confirm a TGD (as well as ensure no cancer is present).

Treatment

There are a few options when it comes to managing TGD cysts: surgical excision, monitor, and needle aspiration.

Given it is benign, one does not HAVE to do anything. If it is infected, it can be treated with antibiotics. The risks of just leaving it alone is that it can get bigger or get (re)infected. With recurrent infections, the overlying skin may become permanently altered (discolored, thinned, thickened, etc). Very rarely, cancer can even develop just like a normally positioned thyroid gland.

If a patient elects to not have surgery, but the size is bothersome, a needle can be inserted into the cyst and the contents suctioned out which would deflate it like a balloon. Downside is that it CAN get bigger again necessitating repeat needle aspiration.

Obviously, surgical excision can be pursued. However, excision is not simply removing what one can see or feel. Simply excising the mass has a high risk of recurrence (33%) because the tract is still there. In order to minimize recurrence after excision, not only is the mass excised, but the entire tract from the thyroid gland all the way up into the tongue is removed known as "Sistrunk Procedure". This procedure also removes the mid-third of the hyoid bone given the tract does go through it.

Even with a Sistrunk Procedure, the TGD cyst can recur (~10%), though not as highly if only the cyst itself is excised (33%). It is thought by some researchers that active infection either before or after the surgery does increase the risk of recurrence.

To perform a Sistrunk, the patient is placed under general anesthesia and an incision made over the palpable mass. Dissection is carried out to carefully excise the cyst, tract, and mid-third of the hyoid bone. The incision itself is usually about 1.5 inches in length. A surgical drain is placed for a few days to prevent hematoma formation.

tgd cyst

Incision is Made

In this patient, incision is made overlying the thyroglossal cyst. The overlying skin and underlying soft tissues are carefully dissected away.

surgery

Thyroglossal Duct Cyst Mass is Exposed

Once the mass is completely exposed, any tracts seen are followed and removed. This may include removal of the central thyroid gland as well as the central part of the hyoid bone.

The skin is than closed over a drain.

 

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