Most teratomas of the mediastinum are benign and only 15-20% account for malignant neoplasms, such as immature teratomas, mature teratomas with malignant transformation, or teratomas concomitant to mixed germ cell tumors.

• 大部分纵膈腔畸胎瘤是良性的，百分之十五至二十是恶性肿瘤，如不成熟畸胎瘤、成熟畸胎瘤并恶性转形、畸胎瘤共存的混合生殖细胞瘤。