Ependymoma, light micrograph. Classic ependymoma is a爓ell-circumscribed and a cellular neoplasm爓ith sheet-like growth pattern. The tumour cells are frequently arranged around blood vessels creating爌erivascular pseudorosettes. Approximately?0% of ependymomas involve the brain, most of them are爄nfratentorial. Most of these cases involve燾hildren爓ith the peak incidence in the first decade. The爎emaining 10% involve the spinal cord, mostly in adults.