A huge neoplasm occupying the right hemithorax in a pregnancy.

Germ cell tumors, like teratoma, typically occur in young adults in their second to fourth decade with equal sex distribution. We firstly report a very rare case of a huge tumor compressed the vital structures of the mediastinum that was diagnosed in a 21-year-old woman at 39 weeks of gestation during a routine prenatal examination. The patient underwent complete en-bloc resection and the size of the tumor was extremely large although no invasion to the vessels or to the airway had occurred. Adherence to the adjacent right pulmonary artery and right main bronchus was present, but without erosion or fistulization. The patient has remained well for over 2 months after the treatment without any signs of disease recurrence.