ACCOMPANYING TEXT
A 41-year-old female patient was referred to the department of head and
neck surgery due to a large submandibular midline mass that had been
present since childhood but had progressively increased in the three
months prior to referral. [Image 1] CT scan of the neck[Image 2] described the lack of eutopic location of the
thyroid gland, scintigraphy indicated that functional thyroid tissue was
located only in the submandibular mass, and FNAC was diagnostic for
benign thyroid tissue. Thyroid function blood tests (TSH and thyroxine)
were normal. A multidisciplinary team of physicians decided for surgical
resection, which included the hyoid bone and adjacent muscles due to the
proximity of the submandibular mass. [Images 3 and 4] The
anatomopathological evaluation confirmed thyroid tissue without any
malignant characteristics present.
Ectopic location of the thyroid gland is a rare event, with a reported
prevalence of 1:100,000 to 1:300,000 in the general population. [1]
This anomaly is due to the embryological development of the thyroid
gland from the base of the tongue to its normal eutopic location in the
lower third of the neck, just anterior to the trachea. [1] Ectopic
location in the trachea, thorax, and abdomen has also been reported.
[2]
Submandibular neck masses present a broad differential diagnosis, with
emphasis on neck malignant disease that must be excluded. [2]
Although malignancy is rare in ectopic thyroid tissue, this diagnosis
should be kept in mind whenever a patient presents with a neck mass.
[1-3] Also, as it is the case in more frequent midline neck masses,
such as in thyroglossal duct cysts, it is important in the diagnostic
workup to exclude the presence of ectopic thyroid tissue, which may
represent the patient’s only functioning thyroid. [3]