What is the diagnosis?
Lingual thyroid. No thyroid tissue in the normal location. Only a small amount of uptake at the base of the tongue.
True or false: The majority of patients with lingual thyroids are euthyroid (normal thyroid function).
What are the 'markers' used for?
Markers are used to aid in localisation and are radioactive sources placed on the patient at specific landmarks, in this case at the chin and at the superior sternal notch. The poor resolution of these scans can otherwise make it difficult to accurately localise a source of activity.
Describe the course of the thyroglossal duct.
The thyroglossal duct arises from foramen caecum located at the junction of anterior two thirds and posterior third of the tongue. From there it passes in front of the body of the hyoid bone, curving backwards and superiorly to reach behind the bone before once more turning inferiorly and continuing to the isthmus of the thyroid.
Where are ectopic thyroids located? Why?
Thyroid tissue may be found anywhere along the course of the thyroglossal duct, however complete arrest with thyroid tissue located at the base of tongue is most common, and represents 90% of all cases of ectopic thyroid.
Tc-99m Pertechnetate (37 MBq) was injected into a vein in the left foot. Images of the neck and chest were obtained. No normal thyroid uptake was seen in expected location in the neck just above the sternal notch. There was some faint increased activity seen at the level of the chin just behind the tongue.