GENERAL
This cyst is the most common congenital abnormality in the neck and usually presents in the first decade of life. 65% of them arise below the hyoid bone.
EMBRYOLOGY
The thyroid extends from the base of the tongue to its normal position in the lower neck. The path or tract it makes may not close leading to a cyst. This cyst may become infected after an upper respiratory tract infection and rarely becomes malignant.
CLINICALLY
Usually after an upper respiratory tract infection there appears a non-tender cyst of about 2 to 4cm in diameter. This cyst is mobile and moves upward when one protrudes the tongue. It is not usually attached to the skin.
INVESTIGATIONS
Ultrasound, CT scan and blood tests are often done to ascertain the nature and position of the cyst and whether there is other thyroid tissue. A radio nucleotide thyroid scan can also be done.
MANAGEMENT
Surgery is the treatment of choice as these cysts are prone to become infected. A Sistrunk is done where the whole tract is excised to the base of the tongue including the cyst and midline portion of the hyoid bone. This operation has a less than 5% recurrence rate.