Cerebral medulloepithelioma--electron microscopy and immunohistochemistry.

A case is reported of a boy, 3 years of age, with a large medulloepithelioma in the left cerebral hemisphere. Medulloepitheliomas are rare tumors of the primitive medullar epithelium. Histological, immunohistochemical and electron microscopical findings are presented. We discuss previously reported cases, the ontogeny of this type of tumor and the relation to the so-called primitive neuro-ectodermal tumors (PNET).