Resection of Mediastinal Teratoma

Mediastinal germ cell tumors are caused by malignant change in a primordial germ cell. Like their gonadal counterparts, mediastinal teratomas are composed of tissues representing one or more of tile embryonic germ cell layers foreign to the organ or anatomic site in which they occur. The tumor may attempt organ formation and can contain teeth, skin, and hair (ectodermal derivatives); cartilage and bone (mesodermal derivatives); or bronclfial, intestinal, and pancreatic tissue (endodermal derivatives). Mature teratomas represent approximately 60% to 70% of mediastinal germ cell tumors and are well differentiated and benign. 3 Those composed exclusively of mature ectoderm are often termed "dermoids." The presence of any fetal or immature neuroeetodermal or mesenehymal elements characterizes a teratoma as immature, which lms a good pro~losis but a greater likelihood of recurrence or metastasis. Rarely, a mature teratoma can contain a focus of careinonla, sarcolna, or malignant germ cell tumor; one that does is termed a nlallgnant teratoma" or teratocarcinonla . Most mature mediastinal teratonias occur in children and young adults, with tile average age at presentation approximately 20 years. ~ Unlike malignant germ cell tumors, which occur nearly exclusively in men, teratomas occur with equal frequency in men antl women. Although the asymptonlatic lesion is more likely benign, tile lack of symptoms does not ensure a benign process. Similarly, a symptomatic lesion is ulore likely malignant, but benign lesions also may be symptomatic. In infants and children, the relatively smaller mediastinal dimeusions and tile predominance of malignant lesions make most mediastinal masses symptomatic. Mature teratomas can be asymptomatic in up to 50% of patients, particularly in chihiren and young aduhs. 5 Older individuals ulorc typically present with signs and symptoms related to intrathoracic compressiou from tile local growth of the mass, with chest pain, cough, and dyspnea as tile most connnon complaints. ConstiOperative Techniques in Thoracic and Cardiovascular Surgery, Vol tutional synlptOUlS snell as fever, weight loss, and endocrine dysfunction lmve also been described. Digestive enzymes secreted by intestinal mucosa or pancreatic tissue in the tumor can precipitate rupture into the bronelfi, pleura, pericardium, or lung. Expectoration of hair (trychoptysis) or sebmn is a rare but pathognomonic event, indicating that the tmnor has rul)tured into a bronchus.