Yolk Sac Carcinoma
Yolk sac carcinomas are so named because their cells look like the yolk sac of and early human embryo. Other names for this type of cancer include yolk sac tumor, endodermal sinus tumor, infantile embryonal carcinoma or orchidoblastoma.
Yolk sac carcinoma is the most common form of testicular cancer in children. When they do occur in children, these tumors are usually treated successfully. When yolk sac tumors develop in adults, however, they are of more concern, especially if they are "pure". Yolk sac carcinomas respond very well to chemotherapy, even if they have spread. This type of tumor almost always increases blood levels of AFP.