Tumors of the Nervous System

1. Gliomas (glial cells within the brain parenchyma)
   1. Astrocytomas - astrocytes
      1. Low-grade astrocytoma (Grade I/II)
      2. Oligoblastoma multiforme (Grade IV)
   2. Oligodendroglioma - myelinating cells of CNS
   3. Ependymoma - lining cells of ventricles
2. Meningioma - epithelial cells of meninges
3. Medulloblastoma - cells of medulla
4. Schwannoma - myelinating cells of PNS
5. Metastasis to the CNS
6. Less common - otherwise non-specified
   1. Hemangioblastoma
   2. Craniopharyngioma
   3. Pituitary tumors

• Primary brain tumors are more common in men, except for meningiomas
• Metastastic brain tumors are much more common than primary tumors
• Risk factors: genetic syndromes, ionizing radiation

In adults, 70% are supratentorial and 30% are infratentorial

Opposite is true for the children; more posterior and caudal also

• Most common brain tumor: Metastasis.
• Most common brain tumor in adults: Glioblastoma.
• Most common brain tumor in adults [benign]: Meningioma.
• Most common brain tumor in adults [malignant]: Glioblastoma.
• Most common brain tumor in children: Astrocytoma.
• Most common brain tumor in children [benign]: Astrocytoma.
• Most common brain tumor in children [malignant]: Medulloblastoma.