Thyroglossal cysts Flashcards
def thyroglossal cysts
a fluid-filled, epithelium lined, sac resulting from incomplete closure of the thyroid’s migration path
a remnant of the thyroglossal duct that forms during the embryonic development of the thyroid gland
aetiology thyroglossal cysts
The thyroglossal duct is a tract of embryonic mesoderm that originates be-tween the 1st and 2nd branchial pouches, represented by the foramen caecum of the tongue.
thyroid gland develops from froamen cecum at the base of the tongue and descends caudally into the neck to a pretracheal site = thyroglossal duct
If the duct fails to obliterate, midline neck cysts or ectopic thyroid tissue can develop anywhere along the path of the thyroglossal duct.
1–2% of cases are associated with lingual or ectopic thyroid tissue. Very rare familial variants (mostly autosomal dominant in prepubertal girls).t
the lining is nonkeratinising stratified squamous, colum-nar or cuboidal epithelium with mucoid material filling the cyst.
epi thyroglossal cysts
approx 7% of population of have thyroglossal duct remnants
mean age presentation is 5yrs
3x more common than brachial cysts
second most common neck abnormality after lymphadenopathy
sx thyroglossal cysts
painless midline neck mass (90%; 10%can be lateral, with 95% of these on the left side).
dysphagia rare - can occur with or w/o tongue base involvement
usually painless but rarely may become infected and cause fever and pain
present from birth - usually detected in early childhood
signs thyroglossal cysts
moves on protrusion of tongue andswallowing
this may help to differentiate it from thyroid nodules, which do not move with protrusion of the tongue
between thyroid notch and hyoid bone
midline round, smooth swelling
can usually be transilluminated
Differential diagnosis: Lymph node, epidermal inclusion (dermoid) cysts, salivary duct abnormality or ectopic thyroid tissue
ix for thyroglossal cysts
if suprahyoid, TFT and isotope to exclude a lingual thyroid - removal may render pt hypothyroid
TSH normal
US - well circumsribed, anechoic midline mass, above the level of the thyroid
US/MRI differentiate from other structures - cysts have a high signal on T2 weighting
ix for neck lumps
virology and TB tests
CT - define mass in relation to anatomical neighbours
CXR may show malignancy or, in sarcoid, reveal bilateral hilar lymphadenopathy.
Consider fine-needle aspiration (FNA) - if infection suspected - gram stain and culture (including AFB and mycobacterial culture)
mx for thyroglossal cyst
excision of cyst and entire duct to preveng recurrance
