En bloc resection of an extremely giant mediastinal immature teratoma with somatic-type malignancy: A case report with a brief review of the literature.

Primary mediastinum immature teratoma with somatic-type malignant transformation (SM) is extremely rare, and the clinical prognosis is poor. Immature teratoma with SM is difficult to eradicate by chemotherapy due to poor sensitivity; therefore, surgical resection is recommended whenever possible because it may offer better survival.