Secretion of human chorionic gonadotropin and α-fetoprotein by an ovarian germ cell tumor of apparent yolk sac origin

α-Fetoprotein (αFP) and four placental proteins, human chorionic gonadotropin (hCG), human placental lactogen (hpL), pregnancy specific β₁-glycoprotein (SP1), and placental protein 5 (PP5), were measured in a 17-year-old patient with endodermal sinus tumor of the ovary. The circulating levels of αFP were consistently high (more than 14 mg/ml), and αFP was localized in tissue sections using immunohistochemical techniques. None of the four placental proteins was detectable in serum samples, but hCG was detected in urinary concentrates in an episodic manner. This ectopic hCG resembled placental hCG in its physicochemical and immunological characteristics. Unlike αFP, hCG was not detected in the tumor by immunohistochemical methods. This study indicates that the neoplasm elaborated both hCG and αFP. Whether pure endodermal sinus tumor of the ovary is capable of secreting hCG cannot be answered by this study because of limited histologic sampling. The likelihood that this represents a mixed germ cell tumor in which only the endodermal sinus tumor element was sampled remains a possibility. This study also indicates that the 24-hr urinary concentrate is far more sensitive than serum samples for hCG detection.