α-Fetoprotein-producing ovarian tumor in a postmenopausal woman with germ cell differentiation

α-Fetoprotein (AFP)-producing ovarian tumors (APOTs) are rarely encountered in postmenopausal women, irrespective of whether they are of the germ cell or non-germ cell type. The APOTs that do occur in postmenopausal women are characterized by variable histologies such as hepatoid carcinoma, yolk sac tumor, and epithelial malignancies, most of which are combined. We herein present a case with APOT, which arose in a 58-year-old, gravida 2, para 2, postmenopausal woman. Preoperatively, the tumor, which was in the right ovary, was found to produce AFP (102768.0 ng/mL). The tumor was evenly composed of glands mimicking secretory endometrial gland or fetal gut accompanied by abundant stroma. Immunohistochemically, these glands were positive for SALL4, glypican-3, and hepatocyte nuclear factor 1β. We considered the present case as an AFP-producing adenocarcinoma with adenofibroma showing germ cell differentiation, but it seemed controversial that this tumor should be designated as a yolk sac tumor of the glandular type. The expression profiles of SALL4, OCT4, glypican-3, and hepatocyte nuclear factor 1β were thought to provide interesting implications to characterize the present case.