Note the orderly arrangement of epithelial cells around fibrovascular cores. Cytologic atypia is absent and mitotic activity is not increased. Choroid plexus papillomas are low-grade tumors (WHO Grade 1) and cured by total resection (100% 5-yr survival). The differential diagnosis in children includes papillary ependymoma and this distinction may be difficult in some cases. In older patients, metastatic papillary carcinomas should be ruled out.