Ependymomas are gliomas that recapitulate the ependymal cells microscopically and ultrastructurally. They commonly occur along the ventricular surfaces and central canal of the brain and spinal cord. Intracranial extra-axial ependymoma (IEAE) is a rare entity and is commonly misdiagnosed clinically and radiologically as a meningioma. The histogenesis of such IEAEs is obscure. A novel recurrent oncogenic fusion involving the C11orf95 and RELA genes was recently described in supratentorial ependymomas. A 9-year-old girl presented with a dural based parafalcine mass that, in addition to exhibiting classical immunohistochemical features of an ependymoma, also demonstrated C11orf95-RELA fusion, characteristic of supratentorial ependymomas. We suggest that IEAEs share their histogenesis with their intra-axial counterparts, arising either from dural extension of subcortical, subependymal rests or directly from ectopic dural rests.
Keywords: RELA; clear cell; ependymoma; extra-axial; supratentorial.
© 2016 Japanese Society of Neuropathology.