CNS Tumors (Excluding Pituitary, PNET, and Embryonal Tumors)

• Published in: Principles And Practice Of Neuropathology
• Main Authors: Parisi, Joseph E., Mena, Hernando, Scheithauer, Bernd W., Rorke, Lucy B.
• Format: Book Chapter
• Language: English
• Published: New York, NY Oxford University Press 20.03.2003
• Subjects: Clinical Neurophysiology; Neurology & clinical neurophysiology; Pathology; Intracranial; Neuroepithelial; Oligodendrocyte; Intrinsic; Neoplasms
• ISBN: 9780195125894; 0195125894
• DOI: 10.1093/oso/9780195125894.003.0016

Gliomas, principally astrocytomas, account for the majority of brain tumors. These intrinsic tumors are derived from neuroectoderm and are classified on the basis of the predominant cell type (astrocyte, oligodendrocyte, or ependymal cell). Although the term glioma applies to all tumors of this group, in practice, glioma usually refers to an infiltrative glial tumor, generally a diffuse astrocytoma or oligodendroglioma. Less commonly, the term glioma has been applied to all tumors of neuroepithelial origin, including those composed of undifferentiated cells, of neuronal elements, and of mixed cell populations. Incidence figures vary widely depending upon the patients studied. Most neurosurgical and neuropathological series report an incidence of gliomas as 40%–45% of all intracranial tumors (Zulch, 1986; Burger and Scheithauer, 1994). Glial tumors are somewhat more common in men (male:female ratio of 3:2), although as a group these are the most common intracranial neoplasms in both sexes. The incidence of gliomas is higher in children than in adults, accounting for about threequarters of all primary intracranial neoplasms in subjects under the age of 15. Childhood gliomas are more likely to be infratentorial in location, primarily involving cerebellum and brain stem, whereas adult examples are more likely to be supratentorial. Although some reports have suggested an increasing incidence of primary brain tumors in recent years, particularly malignant gliomas, careful population-based studies have indicated that this “apparent” increase actually is a reflection of improvements in diagnosis (Radharkrishnan et al., 1995).