Congenital ependymoblastoma presenting as a sacrococcygeal mass in a newborn: an immunohistochemical, light and electron microscopic study.

We describe a case of congenital ependymoblastoma presenting as a subcutaneous mass in the sacrococcygeal area of a newborn male. The tumor was composed of primitive cells disposed in compact sheets and cords and exhibiting focal ependymal differentiation. No other line of cellular differentiation was identified by either immunohistochemistry or ultrastructural study. Elevated serum alpha-fetoprotein was found, which decreased following surgical extirpation of the tumor. We propose that this tumor had its origin in the ependymal medullary vestige, similar to other sacrococcygeal ependymomas.