Benign Brain Tumors
Benign tumors can grow slowly within the brain (intra-axial) or outsIDe of the brain (extra-axial). Because they grow slowly, and the brain shifts to accommodate their growth, many of these tumors do not produce symptoms until quite late in their course - when they are large and more difficult to treat. Other benign tumors become malignant and incurable.
All tumors are derived from the normal tissue within some normal structure that gives rise to a tumor.
Intra-Axial Tumors
These tumors come from the cells that originally form the brain during development (stem cells) or from normal mature cells which make up the brain. The later include the following:
- Neurons (which do all the work of seeing , feeling, moving and thinking).
- Astrocytes, which support the nerve cells (neurons).
- Oligodendroglial cells, which produce the myelin (which electrically insulate the neuron).
- Ependymal cells, which line the fluID filled cavities of the brain (ventricles).
The names of the tumors are similar to their cells of origin:
- Stem cells become ganglioglioneurocytomas.
- Neurons become neurocytomas
- Astrocytes become low grade astrocytoms and pilocytic astrocytomas
- Oligodendroglial cells become oligodendrogliomas
- Ependymal cells become ependymomas
Each of these low grade (benign) brain tumors are potentially curable if treated early when small and still low grade. However, if untreated, the tumor can become malignant and incurable by any means.
Extra-Axial Tumors
Benign brain tumors can arise from structures insIDe the skull which are located outsIDe of the brain. These structures comprise the coverings of the brain (the meninges), the pineal gland, the pituitary, the cranial nerves and the skull. Tumors arising from these structures grow into the brain. These tumors include:
- Meningiomas
- Pineal parenchymal tumors - pinealocytomas
- Pituitary adenomas
- Craniophayngiomas
- Acoustic and trigeminal schwannomas
- Osteomas
These tumors grow slowly and relentlessly and produce neurological symptoms by compressing brain tissue or the cranial nerves, by obstructing the flow of spinal fluID or by causing seizures. Most should be removed surgically. Surgery, in these cases, is safer and easier when the tumor is small. Therefore the earlier they are found - the better.
