Microcystic meningioma arising in a mixed germ cell tumor of the testis: a case report.

We report a case of a microcystic variant of meningioma arising in a mixed germ cell tumor of the testis composed predominantly of mature and immature teratoma with elements of seminoma and embryonal carcinoma. We believe this is the first such case of a meningioma arising in a teratoma within a gonadal or extragonadal site. The meningiomatous component showed positive immunohistochemical staining for epithelial membrane antigen and a lack of staining for cytokeratin, factor VIII, CD31, and alpha-fetoprotein. Recognition of a non-germ cell tumor arising in the setting of a teratoma in the testis may be prognostically important depending on the nature of the non-germ cell component and whether it has spread beyond the testis.