Thyroglossal duct cyst

Overview

The most frequent cervical anomaly is thyroglossal duct cysts. They can develop anywhere along the thyroid's migratory path between the mouth and the inferior neck. They frequently manifest as midline neck cysts near to the hyoid bone.

 

What is a thyroglossal duct cyst?

A thyroglossal duct cyst is a neck mass or lump formed by cells and tissues that remain after the thyroid gland forms during embryonic development. Cysts seldom occur on the tongue, tonsils, or the floor of the mouth. It is most usually diagnosed in preschool-aged children or throughout adolescents, and it frequently arises after an upper respiratory infection, enlarging and becoming uncomfortable.

 

Thyroglossal duct cyst Causes

A thyroglossal duct cyst is an embryologic remnant formed when the thyroglossal duct going from the foramen cecum in the tongue to the thyroid's position in the neck fails to close. The thyroid begins to develop as a median protrusion from the primitive pharynx in the third week of pregnancy. The thyroid primordium emerges from the foramen cecum, which connects the anterior two-thirds and posterior one-thirds of the tongue. The thyroid then descends to the neck, passing anterior and near to the growing hyoid bone. By the seventh week of pregnancy, it has settled into its ultimate place in the inferior pre-tracheal neck.

The thyroglossal duct is a small tubular tube that links the thyroid gland to the foramen cecum when the thyroid descends. In around 50% of persons, the distal section of the duct develops into the pyramidal lobe of the thyroid gland. By the ninth week of pregnancy, the thyroglossal duct has usually involuted. If any part of the duct remains open, discharge from the epithelial lining can cause inflammation and the creation of a thyroglossal duct cyst.

Thyroglossal duct cysts affect around 7% of the world's population. They have an equal number of male and female inhabitants. Although they are the most frequent pediatric mass, they can also be seen in adults with different frequency. These cysts are often connected with the hyoid bone. They are approximately 20% to 25% present at the suprahyoid level, 15% to 20% present at the hyoid level, and 25% to 65% prevalent at the infrahyoid level. 

 

What are the symptoms of a thyroglossal duct cyst?

The most common symptoms of a thyroglossal duct cyst are as follows. However, each child may experience symptoms in a unique way. Symptoms could include:

• A small, soft, round mass in the center front of the neck
• Tenderness, redness, and swelling of the mass, if infected
• A small opening in the skin near the mass, with drainage of mucus from the cyst
• Difficulty swallowing or breathing

The symptoms of a thyroglossal duct cyst may be similar to those of other neck tumors or medical conditions. Always seek a diagnosis from your child's doctor.

A thyroglossal cyst is most commonly seen midline or slightly off midline, between the thyroid isthmus and the hyoid bone, or immediately above the hyoid bone. A thyroglossal cyst can form anywhere along the thyroglossal duct, while cysts within the tongue or the floor of the mouth are uncommon. With tongue protrusion, a thyroglossal cyst will rise higher. Ectopic thyroid tissue is more common in people who have thyroglossal cysts. A lingual thyroid can occasionally be observed as a flattened strawberry-like lump near the base of the tongue.

 

How is a thyroglossal duct cyst diagnosed?

Physical examination is typically used to make a diagnosis. Because the thyroglossal duct frequently attaches near the base of the tongue, the mass usually rises upward when the tongue is stretched and swallowed. It is critical to establish whether or not the thyroglossal duct cyst includes thyroid tissues.

Imaging should be done to both identify the thyroglossal duct cyst and to look for healthy thyroid tissue. If normal thyroid tissue is missing in the inferior neck, the patient and/or parents should be counseled about the prospect of lifelong thyroid replacement treatment following surgery.

Ultrasound is the best first imaging method. Ultrasound is widely available, cheap, and noninvasive. It does not necessitate the use of ionizing radiation or anesthesia, which is vital for treating youngsters. Although CT scans and MRI can be used to assess thyroglossal duct cysts and the presence of normal thyroid tissue, ultrasonography is typically adequate.

Some surgeons recommend for preoperative thyroid function testing. This may be useful if ectopic thyroid tissue is suspected, but there is little evidence to recommend routine lab tests for simple thyroglossal duct cysts.

Other congenital cystic neck tumors might look similar to thyroglossal duct cysts. A dermoid cyst is the most frequent kind. Based on the physical examination and imaging examinations, a dermoid cyst cannot always be separated from a thyroglossal duct cyst, and the answer is not known until the mass is removed and analyzed by a pathologist.

 

Thyroglossal Duct Cysts Management

Because of the low risk of malignancy, thyroglossal duct cysts are surgically removed to prevent recurring infections. Simple thyroglossal duct cyst excision is linked with a significant recurrence rate (45% to 55%). The Sistrunk surgery is regarded the gold standard of surgical therapy, with significantly lower recurrence rates. This method necessitates a more thorough surgical removal of the hyoid bone and a core of base of tongue tissue.

 

Sistrunk Procedure

The Sistrunk technique involves the surgical removal of the hyoid bone's central part as well as a large core of tissue from the midline area between the hyoid and foramen cecum. Excision of the cyst, as well as the path's tract and branches, is required, and removal of the central section of the hyoid bone is recommended to assure full removal of the tract. 

In general, the procedure consists of three steps:

1. Incision
2. Resection of cyst and hyoid bone
3. Drainage and closure

There are several versions of the Sistrunk procedure, including:

• "Classic": excision of the hyoid bone center along with a thyroglossal duct cyst, removal of one-eighth inch diameter core of tongue muscle superior to the hyoid at a 45 degree angle up to the foramen cecum to include mucosa, removal of one-quarter inch of the hyoid bone center, closure of the hyoid bone cut ends, and placement of a drain
• Modified: incision through the base of the tongue but not through the mucosa In both main and revision situations, the modified Sistrunk approach is preferred.
• Hyoid cartilage division: In situations when the hyoid bone has not matured, the non-fused cartilage component can be separated using monopolar Bovie electro-cauterization or scissors. There were no statistical differences between the modified Sistrunk technique and the standard Sistrunk procedure.

The surgery is considered generally safe. There were no serious issues observed in a trial of 35 pediatric patients, however mild complications were observed (6 patients presented with seroma and 4 patients with local wound infections). A more recent study evaluated 24 research articles on different treatment problems of thyroglossal cysts and found that the Sistrunk surgery (traditional or modified) and simple cystectomy treatment methods had a total mild complications rate of 6%. The Sistrunk method also performed better in terms of total recurrence, with the lowest rate of recurrence.

The Sistrunk technique has a 95% cure rate and a long-term survival rate of 95-100%.

 

Before admission to hospital

Preoperative assessment

When your kid is put to the waiting list, you will be required to complete a "health screening questionnaire. This will be completed immediately following your visit if your kid was seen in Addenbrookes, or over the phone if your child was treated at one of our outlying clinics.

Depending on whether your child has any underlying illnesses, he or she may require the services of an anesthesiologist as well as blood testing.

 

Purchasing suitable painkillers

It is critical that you obtain some children's pain relievers such as paracetamol (e.g., Calpol) and ibuprofen before to hospitalization so that you have these at home following release.

 

Starvation plan

Before the procedure, your youngster will be unable to eat or drink. Before surgery, specific instructions will be provided in the letter of confirmation.

 

What happens when my child is admitted to hospital?

On the day of operation, you will be requested to bring your kid to one of our pediatric wards. When you arrive, the nursing team, as well as a specialist and an anesthesiologist, will examine you. A parent will be permitted to accompany your kid to the anesthesia room, where they will be put to sleep for the procedure, and will also be present in the recovery area when they awake.

 

What happens after the operation?

Your kid will be watched for a few hours in our children's recovery section; you will be contacted to be with your child as soon as they awake. Your youngster will subsequently be sent to the pediatric ward.

When your kid is completely awake, they will be able to resume drinking and eating. The nursing team on the ward will administer analgesia (pain relievers) and examine your child's wound.

If your child needs to stay in the hospital overnight, a parent may accompany them. The child's bed provides a bed, and breakfast is served on the ward for the resident parent. Before your kid returns home, plans will be made to remove the drain.

 

Prognosis

The prognosis following the Sistrunk treatment is typically favorable. After Sistrunk, around 10% of thyroglossal duct cysts return. Simple excision without excising the middle part of the hyoid bone has a substantially greater recurrence rate. Less than 1% of thyroglossal duct cysts progress to cancer. The most prevalent kind of cancer identified is papillary carcinoma (92.1%), followed by squamous cell carcinoma (4.3%). Thyroglossal duct cyst carcinoma most commonly manifests as an asymptomatic midline neck tumor. On final pathologic investigation, 73.3% of these forms of carcinomas were discovered as an accidental discovery.

Patients with thyroglossal duct cyst carcinoma are more likely to be adults, having an older average age than the normal thyroglossal duct cyst patient. A Sistrunk treatment is used to treat thyroglossal duct cyst papillary carcinoma, followed by an examination of the lateral neck lymph nodes and thyroid. Depending on the degree of the condition, total thyroidectomy, lateral neck dissection, and/or radioactive iodine may be recommended. With a survival rate of 99.4% and a recurrence rate of 4.3%, the overall prognosis is favorable.

 

Complications

Infection

An infected thyroglossal duct cyst might develop if it is left untreated for an extended period of time or if a thyroglossal duct cyst is not identified. As substantial rim augmentation has developed, placed inferior to the hyoid bone, the degree of infection may be assessed. Because of the cyst's fast development, soft tissue edema, airway blockage, and difficulty swallowing ensue. Infections can cause an expression of fluid to be propelled into the pharynx, creating various difficulties inside the neck.

 

Thyroglossal Fistula

A thyroglossal duct cyst can burst suddenly, resulting in a draining sinus called a thyroglossal fistula. When the cyst is not completely removed, a thyroglossal fistula might form. This is commonly detected when there is bleeding in the neck, which causes swelling and fluid ejection near the initial removal incision.

 

Complication of the Surgery 

The most common consequence of the Sistrunk operation is thyroglossal duct cyst recurrence, which occurs in roughly 10% of patients. Incomplete excision, intraoperative rupture, surgical expertise and experience, and the presence of infection are all risk factors for recurrence. However, even after technically proficient operations, recurrence might occur.

A laryngotracheal injury is an uncommon and sometimes fatal consequence of the Sistrunk surgery that causes problems with the airway, swallowing, and/or voice. It can be caused by removal of the thyroid cartilage rather than the hyoid bone. To avoid this during surgery, it is critical to correctly identify the hyoid bone, thyroid cartilage, and thyrohyoid membrane.

A hypoglossal injury is also uncommon, but has been documented following the Sistrunk surgery, resulting in half-tongue paralysis. Near the lateral section of the hyoid bone, the hypoglossal nerve goes lateral to the hyoglossus muscle and medial to the stylohyoid muscle and lingual nerve. To minimize hypoglossal damage, maintain the hyoid excision medial to the smaller cornu of the hyoid.

 

Conclusion 

Thyroglossal cysts are the most prevalent source of midline neck masses and are most commonly seen caudal to the hyoid bone. Thyroglossal cysts are an irregular neck mass or lump that arises from cells and tissues left behind after the thyroid gland forms throughout embryonic phases. Thyroglossal cysts are formed during birth. A variety of diagnostic methods may be employed to determine the extent of the cyst.