This specimen is from a 20 y/o male who presented with chest pain and cough. A chest CT showed an anterior mediastinal mass. At surgery, the tumor was attached to the thymus. The resection specimen showed a 6 cm well-circumscribed tumor with solid and cystic areas as well as foci of bone, cartilage, and hair. The large cystic space to the left is lined by intestinal-type epithelium. The right half shows mature neural tissue.