31. Giant cell ependymoma of the third ventricle: a case report

Ependymomas are central nervous system (CNS) glial tumours thought to be derived from ependymal lining cells in the ventricles or spinal cord. The 2007 WHO classification of CNS tumours recognises three grades of ependymoma and several subtypes. 1 Giant cell ependymoma is a rare variant of ependymoma characterised by bizarre tumour giant cells with a variable component of more typical ependymoma. It has been described largely as isolated case reports and small series since its first recognition in 1996. 2 Giant cell ependymoma may be either WHO grade II or grade III. It has been described in variety of sites, including: spinal cord, cerebellum, the suprasellar region and cerebral hemispheres. We describe a case of giant cell ependymoma of the third ventricle occurring in a previously healthy 7 year old girl. The morphological features, immunohistochemical findings and ultrastructural features are discussed. As this ependymal subtype is not widely known, it may be confused with several other tumours including: pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma, giant cell glioblastoma and atypical teratoid/rhabdoid tumour (ATRT). The differential diagnosis is discussed as confusion with these other entities may have significant treatment and prognostic implications making recognition of this rare ependymoma subtype vital.