Endocrine Abstracts

Introduction: Ectopic thyroid tissue is a rare embryonic developmental defect that occurs during the thyroid transition from its initial position in the floor of the primitive bowel to a pre-tracheal location. This defect has a prevalence in the general population of 0.3–1/100,000 inhabitants, increasing to 0.5–1/4,000 patients with thyroid pathology. It is more common in women and can be diagnosed at any age, with diagnosis being more common in young individuals.

Clinical case: A 78-year-old woman, referred to our department in September 2017 had complaints of hoarseness and choking with 2 months of evolution. The patient had history of nodular thyroid disease, with total thyroidectomy when she was 18 years old. At age 73, after diagnosis of ectopic thyroid, she underwent partial excision of thyroid tissue from the base of the tongue and anterior cervical region, which revealed Papillary Microcarcinoma. On physical examination it was observed a recurrence of the lesion at the base of the tongue with a nodule of 21×18×17 mm, for which subtotal removal of this region was performed. Histology of the surgical specimen revealed unchanged ectopic thyroid tissue.

Discussion/conclusion: The base of the tongue is the most frequent location of ectopic thyroid tissue, with a prevalence of 90% of all cases reported. The most frequent clinical presentation includes complaints of dysphagia and dysphonia, foreign body sensation, cough and airway compression symptoms that occur with a mean age of 40.5 years. Primary carcinomas of ectopic thyroid tissue are uncommon, with diagnosis of lingual thyroid tissue, thyroglossal ductal cyst, mediastinum, and ovary. They are usually diagnosed only after excision of the lesion, with a more frequently papillary pattern. However, follicular, mixed, Hurtle and medullary patterns are also reported. The approach of these malignant lesions is similar to those of thyroid origin, although the presence of ectopic thyroid tissue may be a therapeutic challenge, both in the surgical approach and in the adjustment of levothyroxine doses.