A thyroglossal duct cyst is a congenital anomaly that forms in the neck. It results from the incomplete closure of the thyroglossal duct, a structure that is present during fetal development. This duct (tube-like structure) serves as a pathway for the thyroid gland as it descends from the base of the tongue to its final position in the neck. Normally, the thyroglossal duct disappears after birth. However, in some cases, remnants of the duct persist and can lead to the formation of a cyst, typically located near the midline of the neck.
In the rest of this blog article, we will learn more about thyroglossal duct cysts as we answer the following questions:
- What are the causes of thyroglossal duct cysts?
- How prevalent is this condition?
- What are the signs and symptoms of a thyroglossal duct cyst?
- How is a thyroglossal duct cyst diagnosed and differentiated from other neck masses?
- How is a thyroglossal duct cyst treated?
- What is the Sistrunk procedure?
- What are some postoperative care and recovery tips for this condition?
- Can thyroglossal duct cysts become cancerous?
- What are common myths about thyroglossal duct cysts?
Causes of Thyroglossal Duct Cysts
As we have just learned, the primary cause of this condition is the incomplete closure which leaves behind a small portion of the thyroglossal duct, which can later develop into a cyst. While thyroglossal duct cysts are typically congenital (present at birth) and sporadic (infrequent and not directly inherited), there have been rare instances of familial clustering, suggesting a possible genetic factor in some cases. Published in the Indian Journal of Surgery in 2017 is an article that reports one of such rare cases, involving a family with 5 people affected with thyroglossal duct cysts. The authors suggest that doctors always take into consideration the family history of patients with thyroglossal duct cysts, as this might help identify other family members who may have the same condition.
Prevalence of Thyroglossal Duct Cysts
Thyroglossal duct cysts are the most common congenital neck masses, representing about 70% of such anomalies, and they can affect people of all ages. However, they are most frequently diagnosed in children and young adults, typically before the age of 30. Estimates suggest that about 7% of the population may develop a thyroglossal duct cyst. Unlike some congenital conditions such as congenital hypothyroidism, thyroglossal duct cysts do not show a significant gender predominance.
Signs and Symptoms of a Thyroglossal Duct Cyst
The most common symptom of a thyroglossal duct cyst is a small, painless lump in the middle of the neck. This lump is typically located just below the chin and may move slightly when the person swallows or sticks out their tongue.
While the cyst is typically present at birth, it may not be immediately visible and often remains asymptomatic for years. However, it can become noticeable later in life, particularly when it becomes enlarged due to an infection. If the cyst does become infected, it may cause pain, redness, tenderness, and swelling in the neck. An infected cyst can also lead to the formation of an abscess, which may rupture and drain through the skin. Some individuals may also notice that the size of the cyst increases or decreases during episodes of upper respiratory infections. A large cyst can press on surrounding structures, making it hard to swallow or breathe.
Diagnostic procedures
Diagnosing a thyroglossal duct cyst typically begins with a physical examination, followed by imaging procedures and sometimes a biopsy to rule out other conditions.
1. Physical Examination
A healthcare provider will assess the location, size, and mobility of the neck lump. Because thyroglossal duct cysts are characteristically found in the midline of the neck and move when swallowing or sticking out the tongue, this helps distinguish them from other types of neck masses. It’s important to distinguish a thyroglossal duct cyst from other neck masses, such as branchial cleft cysts, lymphadenopathy, or thyroid nodules, because an accurate diagnosis ensures that the correct treatment approach is followed.
2. Imaging Procedures
- Ultrasound: This is the most common imaging technique used to evaluate thyroglossal duct cysts. An ultrasound can help determine the size and internal characteristics of the cyst and whether it contains any solid components.
- CT Scan or MRI: In some cases, a CT scan or MRI may be recommended, particularly if the cyst is large or there is suspicion of malignancy (cancer). These imaging tests provide detailed information about the relationship between the cyst and surrounding structures in the neck.
3. Fine-Needle Aspiration (FNA) Biopsy
If there is concern that the cyst could be malignant, an FNA biopsy may be performed. During this procedure, a small sample of fluid or tissue is extracted from the cyst to be analyzed under a microscope.
Treatment options
The primary treatment for a thyroglossal duct cyst is surgical removal, although antibiotics may be prescribed for cases where bacterial infection is present. Here are the most common treatment approaches:
1. Antibiotic Therapy
If the cyst becomes infected, a course of antibiotics is the first line of treatment. This helps manage the infection, reduce inflammation, and prevent further complications like abscess formation. However, antibiotics alone will not eliminate the cyst, as the underlying tissue remains intact.
2. Drainage of Abscess
In the case of an infected cyst that has progressed to form an abscess, drainage may be necessary before surgery. Once the infection has subsided, the cyst can then be removed surgically to prevent future infections.
3. Surgical Removal
Surgery is the definitive treatment for thyroglossal duct cysts. The most common procedure is known as the Sistrunk procedure, which involves removing the cyst along with a portion of the thyroglossal duct and some tissue from the hyoid bone (a small horseshoe-shaped bone located above the Adam’s apple). This approach, which is capable of reducing the risk of recurrence and is considered the gold standard, will be explained in more detail in the next section.
What is the Sistrunk procedure?
The Sistrunk procedure is the most effective and widely accepted surgical approach for treating thyroglossal duct cysts. Developed by Dr. Walter Ellis Sistrunk in 1920, this technique ensures the complete removal of both the cyst and the surrounding tissue to minimize the chance of recurrence.
During the procedure:
- The surgeon removes the cyst along with a portion of the thyroglossal duct, which may extend to the hyoid bone in the neck.
- A small section of the hyoid bone, which lies in front of the neck, is also removed. This is important because the thyroglossal duct is often attached to the hyoid bone. Removing part of the bone ensures no remnants of the duct are left behind.
- Surrounding tissues may also be excised to lower the risk of recurrence.
The Sistrunk procedure has a high success rate, and most patients experience complete resolution of symptoms after surgery. Recurrence rates are very low, particularly when compared to simple excision techniques that don’t include the removal of the hyoid bone.
Postoperative Care and Recovery
Recovery from the Sistrunk procedure is generally smooth, but post-operative care is essential to prevent complications and ensure proper healing. Here’s what patients can expect after surgery:
- Wound Care: Proper wound management is absolutely necessary. Patients are typically advised to keep the surgical area clean and dry. Any signs of infection, such as redness, swelling, or discharge, should be reported to the healthcare provider immediately.
- Pain Management: Mild pain, discomfort, or stiffness in the neck area is normal following surgery. Pain medications may be prescribed for the first few days after the procedure to alleviate discomfort.
- Follow-up Appointments: Patients will need to attend follow-up appointments to ensure the wound is healing properly and to check for any signs of recurrence. Monitoring is important in the early weeks post-surgery.
Most patients can return to normal activities within one to two weeks after surgery. Full recovery typically occurs within a month, though strenuous activities should be avoided until the doctor gives clearance.
Can Thyroglossal Duct Cysts Become Cancerous?
Though thyroglossal duct cysts are generally benign, there is a rare but real possibility of cancer developing within the cyst. The most common type of malignancy associated with thyroglossal duct cysts is papillary thyroid carcinoma, which arises from thyroid tissue present within the cyst.
Cancerous transformation occurs in less than 1% of cases, making it an uncommon complication. However, when it does happen, it is usually diagnosed during or after surgery, either through the discovery of suspicious features in the cyst or through routine pathological examination of the removed tissue.
Key diagnostic steps if malignancy is suspected include:
- An FNA biopsy to extract cells from the cyst to check for cancer.
- Imaging scans like ultrasound or CT may be ordered to assess the structure of the cyst and any irregularities.
- Surgical removal of the cyst along with surrounding tissues. If the suspected cancer is confirmed, further treatment options like thyroidectomy or radioactive iodine therapy may be considered depending on the spread of the cancer.
Common Myths About Thyroglossal Duct Cysts
There are several misconceptions surrounding thyroglossal duct cysts, often due to how rare they are and their association with childhood development. Let’s debunk a few of these myths:
- Myth: Thyroglossal duct cysts only occur in children
Fact: While most cases are diagnosed in childhood or adolescence, adults can also develop symptoms or have the condition diagnosed for the first time. In some cases, a cyst may remain undetected until adulthood, especially if it remains small or asymptomatic. - Myth: The cyst will go away on its own
Fact: Thyroglossal duct cysts do not resolve spontaneously. Once they form, they typically persist and may enlarge over time. Surgical removal is the only definitive treatment, especially if the cyst becomes infected or causes discomfort. - Myth: Surgery for a thyroglossal duct cyst is a risky procedure for children
Fact: The Sistrunk procedure is commonly performed in children and is a well-established, highly effective surgery with a very low risk of complications. Most patients recover fully with minimal risk of recurrence. - Myth: Thyroglossal duct cysts always affect thyroid function
- Fact: Thyroglossal duct cysts are usually separate from the thyroid gland and do not typically affect thyroid function. Only in rare cases where malignancy develops or if the thyroid tissue is involved would thyroid function be impacted.
Key takeaways
- In most cases, a thyroglossal duct cyst is congenital, meaning it is present from birth, although symptoms may not emerge until during childhood or adulthood.
- Despite the relative frequency of thyroglossal duct cysts, familial cases are uncommon, with only a few reported worldwide.
- The long-term prognosis for individuals diagnosed with a thyroglossal duct cyst is generally very positive. Most patients, especially those who undergo the Sistrunk procedure, recover fully without any long-term complications.
- The Sistrunk procedure, which involves surgical removal of the cyst and surrounding tissue, is the gold standard for treatment, with low recurrence rates and a high success rate.
- If left untreated, the cyst can become infected, leading to abscess formation, pain, and potential airway obstruction in severe cases. In very rare instances, cancer may develop.
