Thyroglossal duct cyst
Thyroglossal duct cyst is the most common cause of congenital neck swelling. They may be found in as many as 7% of the population. Most commonly, they present in the first decade of life. However, they are also seen in adults. Thyroglossal cysts usually present as fluctuant swellings in the midline of the neck along the line of thyroid descent. To help confirm the diagnosis It is important to see the cyst moves upwards when the tongue is protruded. This occurs because a thyroglossal cyst is attached to the thyroglossal tract which attaches to the larynx by the peritracheal fascia.
The thyroglossal duct
- The thyroglossal duct is an embryological anatomical structure forming an open connection between the initial area of development of the thyroid gland and its final position
- In the occurrence of a persistent thyroglossal duct, the thyroglossal duct fails to atrophy
- The duct persists as a midline structure forming an open connection between the back of the tongue and the thyroid gland
- This results in a thyroglossal duct cyst
- A thyroglossal duct cyst can occur together with other thyroid problems – so to confirm that the thyroid gland is in its normal place and is functioning normally, a thyroid ultrasound scan and thyroid function test are routinely ordered before thyroglossal duct cyst surgery
Thyroglossal cyst
- A thyroglossal duct cyst or thyroglossal cyst is a fibrous cyst that forms from a persistent thyroglossal duct
- Thyroglossal cysts usually appears as a lump on the midline of the neck or slightly off midline between the isthmus of the thyroid and the hyoid bone or just above the hyoid bone
- A thyroglossal cyst can develop anywhere along a thyroglossal duct, though cysts within the tonsil, tongue or in the floor of the mouth are rare
- Thyroglossal duct cysts account for 70% of congenital neck masses
- Thyroid carcinoma arising in a thyroglossal duct cyst is rare, affecting less than 1% of cysts
- Thyroglossal duct carcinoma, however, may be clinically indistinguishable from a benign thyroglossal duct cyst
Symptoms from a thyroglossal duct cyst
- A thyroglossal cyst may be a painless, smooth and cystic midline neck lump
- However, they may become infected and cause pain and swelling
- Problems such as difficulty breathing and swallowing may develop
Why have a thyroglossal cyst removed?
- The main reason surgical excision is recommended because it frequently becomes infected
- Uncommonly a thyroglossal cyst may become malignant
- A preoperative radiologic diagnosis can help reveal changes which show cancer is more likely and change the type of surgery that is performed
Thyroglossal cyst surgery – Sistrunk procedure
- In 1920 Dr Walter Ellis Sistrunk described the classic operation of thyroglossal cyst excision
- The Sistrunk procedure involves excision of the cyst but also of the path’s tract and branches
- A removal of the central portion of the hyoid bone is indicated to ensure complete removal of the tract
- This procedure was based on the understanding of the embryology and anatomy of the thyroglossal duct cyst and dramatically improved results
- By using Sistrunk procedure to treat thyroglossal cyst the recurrence rate is reduced from 50% to 4%
- Today it is unlikely that there will be a recurrence after such an operation
- Sistrunk procedure is performed under general anaesthesia as a day-stay or overnight-stay procedure
Thyroglossal duct cyst treatment
- Before thyroglossal duct cysts are excised, it is important to demonstrate that normally functioning thyroid tissue is in its usual location
- Thyroid scans and thyroid function studies are ordered preoperatively
- Definitive surgical management requires excision not only of the cyst but also of the path’s tract and branches using the Sistrunk procedure
- The intimate association of the tract with hyoid bone requires simultaneous removal of the central portion of the hyoid bone to ensure complete removal of the tract
- Recurrence is unlikely after such an operation except with skin involvement and intraoperative cyst rupture
Thyroglossal duct cyst and papillary thyroid cancer
- The incidence of malignancy is a thyroglossal duct cyst is estimated at around 1% of cases
- Signs of thyroid cancer in a cyst on imaging include:
- Enhancing mural nodules
- Irregular calcification throughout the mass
- Calcification
- Cervical lymphadenopathy
- Brentano in 1911 and Uchermann in 1915 are credited as being among the first to describe a neoplasm in a thyroglossal duct remnant
- The median age at presentation is 40 years and most patients are asymptomatic (cited by Weiss and Orlich)
Thyroglossal duct cyst carcinoma treatment
- There is still debate regarding the need to remove the thyroid gland in the case of a papillary carcinoma of a thyroglossal duct cyst
- Thyroidectomy is recommended in cases where:
- The thyroid gland is found to be nodular, with a cold nodule in a thyroid iodine uptake scan
- There are enlarged lymph nodes
- There is a history of neck irradiation
Summary
- Treatment for a thyroglossal cyst is called the Sistrunk procedure. This requires surgical resection of the thyroglossal duct to the base of the tongue with removal of the cyst and medial segment of the hyoid bone.
- Although nearly always benign the cyst will be need to be removed if the patient exhibits difficulty in breathing or swallowing, or if the cyst is infected. Even if these symptoms are not present the cyst may be removed to eliminate the chance of infection or development of a cancer (1%) or for cosmetic reasons if there is unsightly protrusion from the neck.
- Thyroid scans and thyroid function studies are ordered preoperatively. This is important to demonstrate that normally functioning thyroid tissue is in its usual area.
For more information
- The original Sistrunk paper is available on-line with a modern commentary, click here.
- For more information about thyroid surgery click here.
About Dr Sistrunk
by Donald C. Balfour
Doctor Sistrunk was born in Tallahassee, Alabama, in 1880. He received the degree of Ph.G. in 1900, from the Alabama Polytechnic Institute, and of M.D. from Tulane University in 1906. He was intern in the Charity Hospital, New Orleans, from 1904 to 1906, was assistant house surgeon in the New Orleans Sanitarium from 1907 to 1909, and practiced at New Orleans from 1906 to 1909, and at Lake Charles, Louisiana, from 1909 to 1910.
In 1911, he went to The Mayo Clinic as assistant in pathology and was appointed first assistant in surgery in 1912, assistant surgeon in 1914, and attending surgeon and head of a section in the division of surgery in 1915. From 1918 to 1929 he was associate professor of surgery, The Mayo Foundation, Graduate School, University of Minnesota.
During this period he displayed an intense interest in all surgical problems but particularly he had a large part in a study of the diseases of the thyroid gland, the breast and the colon and the development of surgical treatment of these diseases. The operation which he proposed for the cure of thyroglossal duct cyst revolutionized the surgical treatment of this condition. He was one of the early advocates in this country of the Kondoleon operation for elephantiasis.
His surgical experience was enormous, and the thoroughness with which he assembled the results of this experience and the clarity with which he presented it gave to his publications both the weight of authority and unusually instructive qualities.
