What is the recommended workup for a thyroglossal duct cyst?

Workup of Thyroglossal Duct Cyst

The recommended workup for a thyroglossal duct cyst should include ultrasound of the neck as the first-line imaging study, followed by fine needle aspiration (FNA) of the cyst and computed tomography (CT) with contrast if there are concerning features. 1

Initial Assessment

• Location: Thyroglossal duct cysts are typically found in the midline of the neck, most commonly at or below the level of the hyoid bone 2
• Clinical presentation: Usually presents as a painless, mobile midline neck mass that moves with swallowing or tongue protrusion 3
• Common symptoms:
  • Painless midline neck mass (most common)
  • Difficulty swallowing
  • Infection with pain, redness, and swelling
  • Rarely, hoarseness (if intralaryngeal extension) 4

Diagnostic Algorithm

Step 1: Imaging

• Ultrasound of the neck (first-line imaging)
  • Advantages: Non-invasive, relatively inexpensive, no radiation exposure 2
  • Findings: Well-circumscribed, anechoic or hypoechoic cystic structure in the midline
  • Can help distinguish from other midline neck masses and evaluate relationship to thyroid gland

Step 2: Fine Needle Aspiration (FNA)

• Perform FNA of the cyst for cytological examination 1
• Helps differentiate thyroglossal duct cyst from other cystic lesions
• Can rule out malignancy (papillary thyroid carcinoma can rarely arise in thyroglossal duct cysts)

Step 3: Additional Imaging (if indicated)

• CT neck with contrast should be ordered if:
  • Suspicious features on ultrasound
  • Concern for malignancy
  • Need to assess extent of the lesion and relationship to surrounding structures 1
  • Planning for surgery
• MRI neck may be considered as an alternative to CT, particularly in children or patients who cannot receive iodinated contrast 1

Step 4: Thyroid Function Tests

• Check thyroid function tests (TSH, free T4) to ensure normal thyroid function 1
• Important to rule out hypothyroidism, especially if the thyroglossal duct cyst contains the only functioning thyroid tissue

Special Considerations

• Atypical presentation: For cysts in unusual locations (e.g., lateral neck or intralaryngeal), more extensive imaging with both ultrasound and CT/MRI is warranted 5, 4
• Infected cysts: If the cyst is infected, treat the infection with antibiotics before definitive surgical management 6
• Malignancy concerns: If FNA reveals atypical cells or if there are suspicious features on imaging (solid components, irregular borders, calcifications), more extensive workup may be needed 1

Pitfalls to Avoid

• Misdiagnosis: Thyroglossal duct cysts can be mistaken for other midline neck masses such as dermoid cysts, lymph nodes, or thyroid nodules 5
• Inadequate imaging: Failure to perform appropriate imaging may lead to incomplete surgical planning and higher recurrence rates
• Missing ectopic thyroid tissue: In some cases, the cyst may contain the only functioning thyroid tissue, making preoperative thyroid imaging essential 6

Definitive Management

Once diagnosed, the standard treatment is surgical excision using the Sistrunk procedure, which involves removal of the cyst, the central portion of the hyoid bone, and the tract leading to the base of the tongue 3, 2. This approach minimizes the risk of recurrence.

By following this systematic approach to the workup of thyroglossal duct cysts, clinicians can ensure accurate diagnosis and appropriate management of this common congenital neck abnormality.