A case of ovarian endometrioid adenocarcinoma with a yolk sac tumor component.

Endometrioid adenocarcinoma of the ovary coexists very rarely with yolk sac tumor (YST). This unusual mixed tumor is thought to be a rare variant of endometrioid ovarian carcinoma because of its aggressive behavior, lack of response to chemotherapy, and unfavorable prognosis. We report a case of ovarian endometrioid adenocarcinoma with a YST component in a postmenopausal woman. The patient was treated by surgery and a combination of bleomycin, etoposide, and cisplatin and taxol and carboplatin. She has been clinically free of tumor for 20 months. Immunohistochemically, the YST component reacted for alpha-fetoprotein. YST areas were negative for both CA125 and sex-hormone receptors. Cytokeratin7 and epithelial membrane antigen were negative in YST, but positive in endometrioid adenocarcinoma. The occurrence of this unusual case suggests that even somatic carcinomas may acquire an extraembryonal germ cell differentiation.