To present a rare case of lingual thyroid detected using a hybrid of single photon emission computed tomography and standard computed tomography in a young woman with hypothyroidism.

A 29-year-old woman was screened for autoimmune thyroid disorders in early pregnancy, and found to have subclinical hypothyroidism. No thyroid tissue was found in the anterior neck upon ultrasonography, raising suspicions of an ectopic thyroid. The patient was treated with levothyroxine throughout the remainder of her pregnancy, and developed postpartum thyroiditis requiring an increase in levothyroxine dosage. Whole-body scintigraphy and zoomed static head and neck scintigraphy were performed. Abnormal 99mTc-pertechnetate uptake was observed in the oral region, whereas no uptake was found in the usual thyroid location. Hybrid imaging using single photon emission computed tomography and standard computed tomography was performed to improve three-dimensional representation of the area of increased activity.

The latter imaging modality detected ectopic thyroid tissue in the tongue.

Whole body 99mTc-pertechnetate scintigraphy and a hybrid of single photon emission computed tomography and standard computed tomography are effective imaging modalities for the investigation of ectopic thyroid tissue. The latter modality is particularly recommended, as it allows more precise spatial visualisation of increased isotope uptake activity in the head and neck.

We report a case of multinodular goitre arising in thyroid tissue within the trachea. This tissue appears to have been implanted at the time of an earlier subtotal thyroidectomy.

A 79-year-old woman presented with a 12-month history of dyspnoea. Forty years earlier, she had been treated for a follicular adenoma with subtotal thyroidectomy. Investigation revealed tumour in the region of the right lobe of the thyroid, extending into and narrowing the trachea. A biopsy was performed, and the patient underwent excision of the right thyroid lobe tumour and cricotracheal resection with anastomosis. Histopathological findings were consistent with a multinodular goitre arising in thyroid tissue within the tracheal lumen.

Intra-operative thyroid tissue implantation in the trachea and subsequent goitre development has not previously been described. This case illustrates the need for careful resection of the thyroid in order to maintain the integrity of normal anatomical structures.

Ectopic thyroid tissue in the submandibular region is exceptionally rare. Nevertheless, the treating physician should consider this condition within the differential diagnosis of a submandibular mass.

Case report of ectopic thyroid tissue presenting as a submandibular mass in a patient with hyperthyroidism, together with a review of the English-literature concerning ectopic thyroid tissue.

To our knowledge, this is the first report of ectopic thyroid tissue presenting as a submandibular mass and causing hyperthyroidism. Removal of the submandibular mass resulted in normalisation of thyroid function, and subsequent reduction in the patient's antithyroid medication dosage. Ectopic thyroid tissue should be suspected in any patient with a submandibular mass. Prior to resection of such a lesion, it is essential to ensure that normal, functioning thyroid tissue is present elsewhere. Ectopic thyroid tissue can also present with pathology similar to that affecting the normal thyroid gland.