Monarch Disease Ontology term MONDO_0021067 (mediastinal germ cell tumor) is a germ cell tumor that arises from the mediastinum. Representative examples include seminoma, embryonal carcinoma, yolk sac tumor, teratoma, and mixed germ cell tumor. Also known as: germ cell neoplasm of mediastinum, germ cell neoplasm of the mediastinum, germ cell tumor of mediastinum, germ cell tumor of the mediastinum, germ cell tumour of mediastinum, germ cell tumour of the mediastinum, mediastinal germ cell neoplasm, mediastinum germ cell tumor.