WHO classification of central nervous system tumors (modified from Escourolle-2 method) WHO classification classifies intracranial tumors (brain tumors) into nine categories: 1. tumors of neuroepithelial tissue 2. tumors of cranial and spinal nerves 3. cerebrospinal tumors 4. tumors of the hematopoietic system 5. germ cell tumors 6. cysts and tumor-like lesions 7. tumors of the saddle area 8. Peripheral spread of local tumors 9. Metastatic tumors The most common clinical manifestation of brain tumors is progressive neurological deficits, usually motor weakness. 54% of patients present with headache and 26% with seizures.