title: Placental yolk sac tumor with divergent endodermal differentiation.
abstract: We report an intraplacental germ cell tumor that was an incidental finding in the placenta of a 34-year-old woman. On pathologic examination, the 4.0-cm tumor was well circumscribed with a thin fibrous capsule. It exhibited three major histologic patterns within a mesenchyme-like myxoid background: a primitive endodermal component, a well-differentiated enteric glandular endodermal component, and a component of fetal hepatic tissue. The primitive endodermal component, the hepatic component, and many parts of the enteric endodermal glandular component were immunoreactive for alpha-fetoprotein. We considered the lesion to be a unique example of a placental yolk sac tumor and only the second reported case of a placental yolk sac tumor.
authors.affiliation: Second Department of Pathology, Showa University School of Medicine, Tokyo, Japan. zan42100@nifty.com
authors.forename: Taka-Aki
authors.initials: TA
authors.lastname: Matsuyama
authors.forename: Miki
authors.initials: M
authors.lastname: Kushima
authors.forename: Toshiko
authors.initials: T
authors.lastname: Yamochi-Onizuka
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Ota
mesh_terms: D000328:Adult; D018240:Endodermal Sinus Tumor / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D010922:Placenta Diseases / Q000378:metabolism / Q000473:pathology*; D011247:Pregnancy