Editing Thyroglossal duct

The most common congenital malformation in the neck

== Pathophysiology ==

* Arise as a cystic expansion of a remnant of the thyroglossal duct tract, which has not completely obliterated, leaving behind epithelial duct cells
* Not usually clinically significant or even detectable; an autopsy study showed a 7% incidence of cyst, which is obviously far more common than it clinically comes to light
* Can occur anywhere along the thyroglossal duct tract, but 60% are between thyroid and hyoid
* Malignant transformation can occur
** PTC is most common, followed by FTC and SCC


== Presentation ==

* Presents as either mass or infection
* Classically move up and down with swallowing or protrusion of the tongue
* Mobile, soft, painless midline upper neck cystic structure


== Investigation ==

* CT in adults or MRI in children
* NM thyroid study if ectopic thyroid tissue is suspected on CT
* FNA can be done to exclude thyroglossal duct cancer if clinically necessary based on imaging findings

== Differential diagnosis ==

* Dermoid cyst
* Branchial cleft cyst
* Lipoma
* Ectopic thyroid

== Management ==

* Infection
** Manage with antibiotics then operate once infection has fully cleared
** Incision and drainage if there is an abscess
* Uninfected
** Remove all identified thyroglossal duct cysts (half become infected at some point, and 1-2% contain cancer, which is difficult to detect clinically)
* Non-surgical candidates
** Percutaneous ethanol injection if cancer can be excluded based on imaging and FNA


== Sistrunk procedure: ==

* Preparation:
* Principles:
** En bloc resection of cyst and duct remnants, and part of hyoid if necessary
* Technique:
** Elliptical transverse skin incision over sinus/cyst
** Sub-platysmal flaps
** Open midline raphe between straps
*** If there are chronic adhesions to surrounding tissues like straps, take a cuff to avoid leaving cyst behind
** Dissect cyst and duct
*** Resect attachments to pyramidal lobe if present
*** Continue upwards until hyoid bone
** Hyoid resection
*** Skeletonise the hyoid on location of planned cuts
*** Release infra-hyoid straps from underside for these areas
*** Clear posteriorly as well but don't enter pharynx
*** Divide just medial to lesser cornu on each side
*** Use bone cutters to excise this segment of bone, keeping it in continuity with the tract
** Then grasp middle segment of cut hyoid with Allis and continue following up
** Dissect to foramen caecum
*** May not be able to feel or see much above hyoid
*** Can have an assistant put a finger in the mouth and push the base of tongue
*** Ideally, ligate just below the foramen caecum
** Haemostasis
** Wash and leak test to exclude pharyngotomy
** Small drain?
** Reapproximate straps, platysma and skin
* Complications:
** Lingual nerve injury
** Recurrence
** Hypothyroidism!

[[Category:ENT]]