Hepatoid yolk sac tumor of the ovary (endodermal sinus tumor with hepatoid differentiation): a light microscopic, ultrastructural and immunohistochemical study of seven cases.

Seven cases of ovarian yolk sac tumor (endodermal sinus tumor) with patterns resembling those of hepatocellular carcinoma were encountered in patients 7-43 years of age. Two of the patients had gonadal dysgenesis with a 46XY karyotype. At operation three tumors were confined to the ovary and four were associated with intra-abdominal metastases. Two of the Stage I tumors recurred within one year. The hepatoid pattern was a prominent feature of all the tumors and was exclusive in four of them. In one specimen it merged almost imperceptibly with a polyvesicular vitelline pattern. The hepatoid component of the tumors was characterized by discrete masses, nests and/or broad bands of large polyhedral cells with central nuclei and prominent nucleoli; gland-like spaces, some of which contained mucin, were occasionally evident. Each tumor contained numerous PAS-positive, diastase-resistant intracytoplasmic and extracytoplasmic hyaline bodies. Alpha-fetoprotein and alpha-1-antitrypsin were identified by immunoperoxidase and immunofluorescence techniques in four tumors and albumin in two. Immunoperoxidase stains for chorionic gonadotropin were negative in four cases. Ultrastructural analysis of two specimens disclosed features similar to those of hepatocellular carcinoma.