Endocrine Abstracts

A 23-year-old man initially presented to his GP with palpable ‘gland in his neck’ for 9 years. He was otherwise well with no medical problems. He has a family history of hypothyroidism. Examination revealed right submandibular gland enlargement and lymph nodes in the anterior cervical region bilaterally. His TPO antibody was negative and the only abnormal result was a raised TSH of 12.7. He was commenced on 50 μg of thyroxine daily. Ultrasound of the neck showed no normal thyroid gland and an abnormal oval lesion beneath the strap muscles underlying the normal right submandibular gland. This was confirmed on CT scan, which showed another swelling at the base of the tongue. Technetium Thyroid scan showed increased uptake in the region of the right submandibular gland and at the base of the tongue with absence of uptake in the usual region of the thyroid. This confirmed the presence of ectopic thyroid tissue. Ectopic thyroid tissue has been reported to be found at the foramen caecum and along the thyroglossal duct, where its localization can be explained by the embryogenesis of the thyroid gland. The presence of thyroid tissue outside this pathway has been reported in the submandibular region, parotid gland, gallbladder, skin, liver, trachea, mediastinum, heart, lung, duodenum, iris, and adrenal glands and these cannot be explained readily by embryogenesis. It has been suggested that the possibilities for the presence of thyroid tissue in the submandibular region include abnormal migration during the course of embryonal development, spread of tissue during surgery on a normally located thyroid gland and metastasis of thyroid carcinoma. Malignancy in this patient is unlikely because of a negative family history for thyroid cancer and the young age of the patient. This case represents an unusual description of thyroid tissue at right submandibular region and foramen caecum.