Thyroglossal cyst

· Epithelial 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.

Clinical

· 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

· Symptoms

— Lump

— moves on swallowing and on tongue protrusion

— Transilluminates

· Complications

— Infection

— Rupture or trauma ’ sinus

— Cancer (tends to be papillary)

Investigations

— FNA

— USS to confirm presence of normal thyroid

Treatment

· 25% recurrence if cystectomy alone, 5% if hyoid also taken (Mastery p385)

Sistrunk operation

· 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.

Thyroglossal sinus

· 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)

• males=females

• 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

• midline

• rises with swallowing or protrusion of the tongue

• lined by pseudostratified ciliated columnar epithelium, squamous epithelium, or

both, ± 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

cysts

• 1%

• papillary ca most common

• also Hurtle cell, squamous and anaplastic ca

• requires total thyroidectomy (may be metastatic) and iodine ablation

Lingual thyroid

· 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