There are five common organs in the body where tumours develop and back off partially and circulate in the bloodstream to eventually develop metastases in the brain. They include:
- Skin (Melanoma)
- GI tract
All these together account for about four fifths of brain tumours that are not isolated to the brain tissue itself. The meninges also frequently receive tumour cell from other parts of the body. Pathologists are able to tell metastatic tumours apart from primary tumours by demarcated masses and swelling around the tumour site.
There are three types of paraneoplastic syndromes that involve the CNS and they include:
- Subacute cerebellar degeneration
- Limbic encephalitis
- Subacute sensory neuropathy
The paraneoplastic syndromes sometimes appear before the tumour is diagnosed, and most patients have antibiotics against tumour antigens.
What are the characteristics of the paraneoplastic syndromes?
Subacute cerebellular degeneration
- Ataxia (loss of bodily movements)
- Mild inflammatory infiltrate
- Gliosis (division and expansion of neural cells)
- Destruction of Purkinje cells
Effects are centred in the medial temporal lobe, and they include:
- Neuronal loss
- Subacute dementia
- Microglial nodules
- Perivascular inflammatory cuffs (white blood cells around blood vessels)
Subacute sensory neuropathy
- Altered pain sensation
- Loss of sensory neurons from dorsal root (spinal) ganglia