title: Primary yolk sac tumor concomitant with carcinosarcoma originating from the endometrium: case report.
abstract: BACKGROUND
  A primary yolk sac tumor (YST) with carcinosarcoma originating from the endometrium is extremely rare, to our knowledge, this is the third documented instance. Several hypotheses exist is to its histogenesis.
  
  
  METHODS
  A 65-year-old Japanese woman was diagnosed with a uterine malignancy and underwent surgical treatment and chemotherapy. The postoperative diagnosis was primary carcinosarcoma concomitant with a YST of the uterus. Immunohistochemical staining revealed that the tumor area suspected to be a YST was positive for alpha-fetoprotein.
  
  
  CONCLUSIONS
  We report a case of carcinosarcoma concomitant with a YST of uterus. This case is the third documented instance of a YST with concomitant with carcinosarcoma originating from the endometrium. The histogenesis in this case is suggests aberrantly differentiated somatic cells.
authors.affiliation: Department of Aging and Reproductive Medicine, Kochi Medical School, Kohasu, Okocho, Nankoku, Kochi 783-8505, Japan. ogurih1966@yahoo.co.jp
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Oguri
authors.forename: Ruriko
authors.initials: R
authors.lastname: Sumitomo
authors.forename: Nagamasa
authors.initials: N
authors.lastname: Maeda
authors.forename: Takao
authors.initials: T
authors.lastname: Fukaya
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Moriki
mesh_terms: D000368:Aged; D002296:Carcinosarcoma / Q000473:pathology*; D018240:Endodermal Sinus Tumor / Q000473:pathology*; D016889:Endometrial Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans