Germ Cell Tumors of the Mediastinum / Thymus

Clinical

Pattern and behavior is related to age and gender
- Adolescent and adult
  - Female
    - Nearly all are mature teratoma
      - Benign
  - Male
    - Most common is mature teratoma
      - Benign
    - Other germ cell types are malignant
- Prepubertal
  - Nearly all are male
    - Teratoma may be mature or immature
      - Benign except for local growth
    - Most others are yolk sac tumor
      - Malignant
As many as 8% of male patients with mediastinal germ cell tumors have Kleinfelter syndrome
- All types may be seen