Thyroglossal duct cyst CT image

• Most common congenital anomaly of the neck

• • 2-4% of all neck masses

• Over half present in the first decade of life but may also be seen in adults
• Pyramidal lobe of the thyroid is the most common remnant of the thyroglossal tract (50% of population)
• Etiology

• • Represents a persistent epithelial tract during the descent of the thyroid from the foramen cecum to its final position in the anterior neck
  • Normally this duct obliterates early in fetal life

• Histologically

• • Well-defined cyst with an epithelial lining composed of either squamous or respiratory epithelium
  • There can sometimes be islands of thyroid tissue lying in the walls of the cysts
  • Cysts are filled with mucoid or mucopurulent material, depending on whether the cyst has been infected

• Types of thyroglossal duct cysts

• • Infrahyoid type
    • 65% and is mostly found in the paramedian position
  • Suprahyoid type
    • Nearly 20% and is positioned in the midline
  • Juxtahyoid cysts
    • 15%
  • Intralingual location
    • 2%
  • Suprasternal variety
    • 10% of cases
  • Intralaryngeal
    • Very rare

• Clinical

• • Nontender and mobile masses
  • Infected cysts may manifest as tender masses with
    • Dysphagia
    • Dysphonia
    • Draining sinus
    • Fever
    • Enlarging neck mass
  • Often appear after an upper respiratory tract infection
  • Airway obstruction possible, especially with intralingual cysts
  • The pathognomonic sign is that the cyst moves with tongue protrusion

• Imaging

• • Ultrasound and CT scanning are the radiologic tools of choice
  • Ultrasound is the gold standard
  • Ultrasound can distinguish between solid and cystic components
  • CT scanning may reveal a well-circumscribed cystic lesion, 2-4 cm in diameter with capsular enhancement
  • Thyroid scanning may be done to rule out the cyst containing the only functioning thyroid tissue

• Differential diagnosis

• • Dermoid cyst
  • Lymphadenopathy
  • Sebaceous cysts
  • Schwannomas
  • Lymphatic malformations

• Complications

• • Infection is probably the most common complication
  • Local growth and invasion is extremely uncommon
  • Carcinoma is extremely rare
    • Occurs in about 1% to 2% of patients
  • Thyroid ectopia
    • Fewer than 5% of these cysts actually have ectopic thyroid tissue

• Treatment

• • Surgical treatment of choice for thyroglossal cysts is the Sistrunk operation
    • Includes dissection of the hyoid bone and the base of the tongue
  • Recurrence is approximately 3-5% and is increased by incomplete excision and a history of recurrent infections
  • Thyroid suppression therapy is done by many practitioners
  • Recurrence is the most common complication and is managed with a central neck dissection

Thyroglossal duct cyst . Reconstructed CT scan of the neck demonstrates a midline cystic
lesion (red arrow) with a slightly enhancing wall. The contents measured fluid density.