Teratocarcinoma is a mixture of embryonal cell carcinoma and teratoma, while so-called mature teratoma implies that embryonal cell carcinoma must have been present but has changed to a more mature (differentiated), more normal-appearing and less malignant cell form either spontaneously or because of therapy. There is also a very rare and aggressive teratocarcinoma variety called sarcomatous teratocarcinoma, which is not very responsive to the chemotherapy now available and is categorized as a poor-risk cancer.
Pure yolk-sac tumors are extremely rare and more frequently observed in the chest (mediastinum), except in children under 15, where it accounts for 90 percent of testis cancers. The testes, which are derived from the yolk sac early in the embryo's development, move to an area called the urogenital ridge. Since the embryonic germ cells from this ridge travel almost the whole length of the developing body to their destination in the scrotum, bits of primitive tissue called embryonic rests can be left behind during the migration. This explains why some germ cell tumors are found in non-testicular (extragonadal) sites in the chest or abdomen.
How It Spreads There is a difference in the way cancers of the testis spread. Right-testis tumors spread by the spermatic cord and its associated blood and lymph vessels into lymph glands surrounding and between the large blood vessels, the aorta and the inferior vena cava (interaortocaval).
Left-testis tumors drain via the spermatic cord vessels into the left kidney artery and venous lymphatic areas and to lymph nodes just below the left kidney. They generally are not found in the interaortocaval nodal system as frequently observed with right-side tumors. Unless surgery has disturbed the scrotum—to remove the testis
