Carcinoma arising in median ectopic thyroid (including thyroglossal duct tissue)

Carcinoma may arise in ectopic thyroid tissue. In this report, seven cases of papillary carcinoma found in association with median ectopic thyroid rests are discussed. Six patients presented with midline lesions in the thyrohyoid space. These were diagnosed clinically as thyroglossal duct cysts. The seventh lesion was described as a mass in the region of the submandibular salivary gland. All seven patients were treated initially with local resections. Ectopic apparently normal thyroid follicles were demonstrated in all seven specimens; in four, a thyroglossal duct cyst was also recognized. A separate microscopic focus of papillary carcinoma was identified in the thyroid gland in one of the three individuals who subsequently underwent total thyroidectomy. None of the seven patients, followed for from 6 months to 15 years, has had clinical evidence of recurrent disease. The differentiation between a carcinoma arising in median ectopic thyroid tissue and a metastatic papillary carcinoma from an occult primary in the main thyroid gland is discussed.