ABSTRACT
Central nervous system (CNS) tumors are a heterogeneous group of neoplasms divided into two broad categories, glial and non-glial. Non-glial tumors are derived from such diverse structures as the pineal gland, meninges, germ cells, and hematopoietic cells, as well as metastases. Primary glial neoplasms, or those which originate from astrocytes, oligodendrocytes, or ependymal cells, include astrocytomas, oligodendrogliomas, ependymomas, and mixed gliomas. Each entity has a unique morphology and pattern of biologic behavior which portends a distinct prognosis and outcome. Individual outcomes show some variability based on tumor location and age of symptom onset; however, the underlying aggressiveness of the tumor often dictates the time course of the disease. With the advent and widespread use of fluorescent in-situ hybridization and polymerase chain reaction (PCR) techniques, molecular phenotyping of brain tumors has become mainstream and is now an integral part of patient care. The molecular genetics of CNS tumors is a rapidly growing field, and the volume of discoveries is growing at an ever increasing rate, compelling the need for updates in this exciting area of science.