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Woman presents with sudden appearance of an Adam’s apple
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A 44-year-old nurse was referred for the evaluation of a midline neck mass. She noted a sudden appearance of a nontender mass in the midline in the anterior neck under her jaw that looked like an Adam’s apple.
She did not have dysphagia, change in voice, upper respiratory symptoms or cough. She had a 17-year history of hypothyroidism after the birth of her third child. Her thyroid levels have always been well controlled on levothyroxine 125 mcg daily, with a recent normal thyroid-stimulating hormone of 1.5 mIU/L. An MRI showed a 2 cm x 2 cm x 1.5 cm mass that was contiguous with the posterior portion of the tongue and pointed to the foramen cecum. The mass was also contiguous with the hyoid bone (Figures 1A, 1B and 1C). The cystic mass was hypointense on T1-weight images and hyperintense on T2-weight images with a minimal rim of enhancement with gadolinium (Figures 1B, 2).
Stephanie L. Lee
Tests, diagnosis
An ultrasound was performed that revealed a 2.2 cm x 2.8 cm x 1.4 cm superficial simple cyst located in the upper anterior neck (Figure 3). No solid component was seen within the cyst. Both lobes of the thyroid were seen in the lower neck at the normal location of the thyroid gland (Figure 4). The thyroid was hypoechoic and heterogeneous, consistent with chronic thyroiditis. During the next 3 months, the mass decreased in size until it was no longer palpable.
Location of thyroglossal duct cysts. T1-weighted MRI of the neck with gadolinium contrast: A) sagittal, B) coronal, C) axial. Red arrows indicate the location of the hyperintense (compared with CSF) mass. Yellow arrow indicates the small amount of wall enhancement after gadolinium contrast.
This mass is a cyst within the vestigial thyroglossal duct and the most common congenital neck mass that occurs in 7% of the population. The thyroglossal duct extends from the foramen cecum at the base of the tongue to the thyroid gland. During fetal development, the embryonic thyroid migrates through the thyroglossal duct from the foramen cecum to the final position at the base of the anterior neck. After the thyroid migration, the thyroglossal duct usually involutes but can persist anywhere along the path of the thyroglossal duct to form a cystic structure. The locations of thyroglossal duct cysts are usually infrahyoid (65%) or suprahyoid (20%), but, as in this patient, 15% may occur at the level of and involve the hyoid bone. The differential for this cystic mass is a cystic metastatic node or a thrombosed jugular vein. Thyroglossal duct cysts are associated with an ectopic thyroid gland in as many as 1% to 2% of cases. It is recommended to perform a thyroid ultrasound to confirm the presence of a normal thyroid before the removal of the thyroglossal duct.
T1- and T2-weighted axial MRI images. The thyroglossal duct cyst (red arrow) is located at the level of the hyoid. Typical of a cystic structure, the mass becomes very hyperintense on T2-weight images when compared with the T1-weighted images.
Thyroglossal duct cysts have a variable appearance on MRI. As demonstrated by this case, thyroglossal duct cysts are iso- or hyperintense to cerebral spinal fluid (CSF) on precontrast T1-weighted MRI images (Figures 1A, 1B, 1C and 2A) with some rim enhancement with gadolinium contrast (Figure 1B). As typical of all cysts, the thyroglossal duct cysts are hyperintense on T2-weight images, especially when performed with long repetition/short echo time sequences. Most thyroglossal duct cysts do not become completely hypointense (suppress) on fluid-attenuated inversion-recovery (FLAIR) images and remain slightly to moderately hyperintense. About two-thirds will show high signal intensity on diffusion-weighted images.
Ultrasound of the neck mass. Ultrasound confirms a simple cyst with posterior enhancement at the location of and just superior to the hyoid bone. No solid component was seen in the cyst. A. Transverse. B. Sagittal.
Thyroglossal duct cyst management
The management of small thyroglossal duct cysts is controversial. Many endocrinologists will watch without treatment once it has been established that the cyst is small, stable in size and there is absence of a solid component. There is a small 1% to 2% risk for thyroid malignancy, usually papillary thyroid carcinoma in these structures. Although some studies suggest that the outcome of papillary thyroid carcinoma is the same as primary thyroid carcinoma, other studies suggest that malignancy in thyroglossal ducts may be more aggressive with direct tissue invasion and metastatic nodes. Treatment should be assessed based on the same criteria as primary thyroid cancer according to the American Joint Committee on Cancer staging and American Thyroid Association Risk Assessment.
Ultrasound of the thyroid: Ultrasound confirms that both lobes of the thyroid were present in the lower anterior neck. The thyroid was normal in size but was hypoechoic and heterogeneous, consistent with chronic thyroiditis. A. Left lobe, transverse. B. Left lobe, sagittal. Images reprinted with permission from: Stephanie L. Lee, MD, PhD
The recurrence rate of a thyroglossal duct cyst is very high after simple resection. The surgical procedure of choice, the Sistrunk procedure, was described in 1920. The Sistrunk procedure has not changed in the intervening years and requires an extensive resection of the thyroglossal duct cyst, the central portion of the hyoid bone and the thyroglossal tract extending to the back of the tongue to the foramen cecum. Even with this extensive resection, the recurrence rate after surgery is about 6%. Because of the extent of this surgery, I recommend resection only if the cyst is large, symptomatic, varies in size or prior infection. The risk of nonsurgical treatment is infection of the cyst with local inflammation and fibrosis, making future resection more difficult.