Masses of thyroid origin are usually confined to the cervical region. Extension into the retrosternal mediastinal space is not uncommon. The gland in these instances can be palpated in direct continuity with the substernal extension. There is usually no difficulty in diagnosis and surgical extirpation through the conventional cervical approach. This paper will concern itself only with masses of thyroid origin in which the main bulk of the tumor is located below the thoracic inlet and within the mediastinum. Confusion exists in the literature in regard to the differentiation of these two distinct groups of thyroid lesions. Therefore, the incidence of intrathoracic thyroid masses reported in the literature varies with the authors and their use and understanding of the terminology.* If the above criteria are adhered to,† the incidence of mediastinal goiters is stated to be about 1% to 2%.
Anatomic factors which play a role in the descent of