remnant of tract from descent of thyroid
- thyroid descends from foramen caecum (2/3 toward back of tongue in midline; inverted V) to resting position in front of thyroid cartilage.
— hypertrophies and secretes mucoid fluid
— Lining columnar or squamous ± thyroid tissue.
· Occurs from foramen caecum to sternum.
— 75% @ or just below hyoid
— 15% @ level of thyroid cartilage
· Midline 90%
— L of midline 10%
· Usually presents in childhood
— Mean age 5yrs
— moves on swallowing and on tongue protrusion
— Rupture or trauma ’ sinus
— Cancer (tends to be papillary)
— USS to confirm presence of normal thyroid
· 25% recurrence if cystectomy alone, 5% if hyoid also taken (Mastery p385)
· Transverse incision over cyst through platysma
· Raise sub-platysmal flaps
· Dissect cyst free from below, leave attachment to hyoid
· Divide straps from mid hyoid
· pass right angle around hyoid, divide mylohyoid and geniohyoid from mid hyoid
· divide centre 1-1.5cm of hyoid
· follow duct remnant up (can assist by depressing base of tongue) suture ligate as high as possible.
· persistence of tract or bursting of cyst
What is the incidence of thyroglossal duct cyst
• most common congenital cervical abnormalities (3x more common than branchial cleft remnants)
• most present in childhood
What are the clinical features of thyroglossal duct cyst
• anywhere from submental to suprasternal notch; usually located just below the hyoid
• usually the track passed within or posterior to the hyloid bone
• rises with swallowing or protrusion of the tongue
• lined by pseudostratified ciliated columnar epithelium, squamous epithelium, or
± thyroid remnants in wall
- may contain only thyroid tissue in the body.
What is the management of a thyroglossal duct cyst
• USS to confirm normal thyroid present (DDx ectopic thyroid)
• Sistrunk procedure
• transoral marsupialization or excision for a lingual TDC
What is the incidence of malignant change in thyroglossal duct
• papillary ca most common
• also Hurtle cell, squamous and anaplastic ca
• requires total thyroidectomy (may be metastatic) and iodine ablation
· Failure of decent F>M,
· can cause local symptoms eg stridor
· Can be (often?) only thyroid tissue present.
· Ca risk higher than normal
— But no MCT as no C-cells
· Rx: Decrease size with T4 . I131 ’ surgery