CNS neoplasia I
Intracranial tumours
In adults, primary intracranial tumours represent only 3% of tumour-related deaths, and have an annual incidence of 4–7 per 100 000. Intracranial metastases are more common. Intracranial tumours are the second most common tumour in childhood with an annual incidence of 2–3 per 100 000.
Pathology
Intracranial tumours can be divided into intrinsic and extrinsic (Table 1).
Table 1 Approximate frequency of different intracranial tumours
| Tumour | Percentage of total | Comments |
|---|---|---|
| Intrinsic | ||
| Glioblastoma multiforme | 20 | High-grade glioma; poor prognosis |
| Astrocytoma | 10 (48 in children) | Lower-grade glioma |
| Metastases | 10* | Often multiple |
| Oligodendroglioma | 5 | Slow growing. Often frontal or temporal and calcifies |
| Ependymoma† | 5 (10 in children) | Arise from ependymal lining, usually of 4th ventricle |
| Medulloblastoma† | 5 (45 in children) | Arise from cerebellum. May metastasize within CNS |
| Primary CNS lymphoma | Rare except in AIDS | May be multifocal |
| Extrinsic | ||
| Meningioma† | 15 | Arise from meninges and indent brain, may erode bone |
| Pituitary adenoma† | 7 | Chiasmatic visual disturbance and endocrine effects |
| Schwannoma, e.g. of acoustic nerve† | 7 | Benign |
| Other | 16 | Includes teratomas, pinealomas, etc. |
Estimates are taken from a combination of series
* Metastases are much more common. This estimate is of those with solitary intracranial metastases
Intrinsic
The pattern of tumours differs in adults and children. In adults (see Table 1), 70% of tumours are supratentorial; in children, 70% of tumours are infratentorial.
