Teratoid tumors are most common in young adults 18 to 25 years of age. They originate from germ cell rests that were deposited in the mediastinum during embryogenesis. Dermoid cysts are usually benign cystic tumors composed of epidermal and dermal tissue, and on occasion, hair, bone, or teeth form within these lesions. As with thymomas, calcification may be present along the periphery of the tumor. A potential complication of dermoid cysts and cystic teratomas is rupture and subsequent discharge of the cyst contents into the mediastinum or tracheobronchial tree.
Surgical excision is the treatment of choice.
Cervical goiters may extend inferiorly into the thorax. On occasion, masses within the mediastinum, usually located anteriorly, that have no palpable cervical connection prove to be intrathoracic goiters. Most patients with nodular colloid goiters are asymptomatic, but some lesions grow sufficiently large to compress the trachea, causing dyspnea and stridor. Dysphagia, vascular compression, and vocal cord paresis or paralysis are other potential presenting manifestations. Uptake of radiolabeled iodine by a mediastinal mass on thyroid scan is diagnostic, but this is a relatively infrequent finding because most of these lesions are nonfunctioning goiters.