Ovarian endometrioid adenocarcinoma with ectopic production of alpha-fetoprotein

alpha-Fetoprotein (AFP) is well known as a tumor marker of ovarian endodermal sinus tumor or embryonal carcinoma in gynecological malignancies. However, AFP production is extremely rare in ovarian epithelial cancers. Here we report a case of a 53-year-old woman with an AFP-producing ovarian endometrioid adenocarcinoma. The serum AFP level was elevated up to 2759 ng/ml preoperatively, with a subsequent decrease to the normal range after treatment. Histological examination of the tumor revealed a well-differentiated endometrioid adenocarcinoma with small foci of clear cell components. None of endodermal sinus tumor, hepatoid carcinoma, or embryonal carcinoma components were observed. Immunohistochemical analysis revealed that AFP was expressed in the cytoplasm of the endometrioid glandular lesions, but not in the clear cell components. This is probably the first case of a pure type of ovarian endometrioid adenocarcinoma with significant levels of AFP expression.