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Thyroglossal duct cyst

A 70 year old female with palpable neck swelling for 2 months. Swelling moved with deglutition / tongue protrusion.

Sagittal, axial and coronal images of CECT Neck demonstrates a well defined, midline thin-walled cystic lesion. It shows thin rim of enhancement and internal septations within.
The lesion is located in the infrahyoid region with subhyoid extension. It measures 13 x 19 x 20 mm.
No evidence of calcification or any enhancing mural nodule. No perilesional fat stranding or infiltration into adjacent structures. No evidence of any bony erosion of hyoid bone.

Thyroglossal duct cyst (TGDC)

Thyroglossal duct cysts are one of the most common congenital cystic lesions seen in the midline neck region.
They are congenital lesions formed as a result of failure of regression of segments of thyroglossal duct.
They are most commonly found in the infrahyoid region in the midline (65%-70%).
TGDCs characteristically show movement with deglutition or protruding the tongue.
They are usually seen within 2 cm of the midline.
Ultrasound is usually the first line of imaging. It shows a well-defined anechoic to hypoechoic midline cystic lesion with post acoustic enhancement.
CT features consist of a well-circumscribed cyst with fluid density and thin rim enhancement.
On MRI, TGDC is seen as a T1 hypointense(fluid contents) to T1 hyperintense (protein contents) cystic lesion. High signal intensity is seen on T2 WI with rim enhancement on post-contrast studies.
TGDCs are commonly associated with Ectopic thyroid.