ABSTRACT
EPIDEMIOLOGY AND AETIOLOGY Intracranial and spinal tumours account for only 2 per cent of all malignant neoplasms, but in children they are the second most common tumour type and the most common cause of cancer death. Of all intracranial tumours, roughly 40 per cent originate from neuroepithelium, 35 per cent from meningothelial cells, 14.4 per cent from oral ectoderm (pituitary adenomas and craniopharyngiomas), and 7.5 per cent from peripheral nerve sheath elements. Lymphomas and germ cell tumours account for 2.3 and 0.5 per cent, respectively.27 The 2007 classification of the World Health Organization (WHO) for central nervous system tumours lists over 120 different types and subtypes.108 The incidence, localization, age distribution, biological behaviour and patient survival differ greatly among them. For these reasons, it is also likely that the aetiologies and biological underpinnings of many central and peripheral nervous system (CNS and PNS) tumours vary.
