Brain metastases and paraneoplastic syndromes
- Lesion
Cancers from the lung, breast, skin and kidney often spread to the brain; others act at a distance by antibodies that attack nerve tissue.
What it is
Metastases are the most common brain tumours in adults. They usually arrive through the blood and lodge at the grey-white junction, where vessels narrow, forming well-defined masses with much edema. Lung, breast, melanoma, kidney and colon are the usual primaries; cancer can also spread diffusely through the meninges (carcinomatous meningitis). Paraneoplastic neurologic syndromes are immune attacks on the nervous system triggered by tumour antigens, often appearing before the cancer is known.
Step by step
- A tumour expresses a protein normally restricted to the nervous system.
- The immune system reacts and makes antibodies and T cells against it.
- Activated cells and antibodies cross into the nervous system.
- T cells destroy neurons with intracellular antigens; antibodies to surface antigens alter function.
- The neurologic syndrome often appears before the cancer is found.
Paraneoplastic neurologic syndromes
| Syndrome | Antibody | Usual tumour | Target |
|---|---|---|---|
| Cerebellar degeneration | Anti-Yo (PCA-1) | Ovary, breast | Purkinje cells |
| Limbic encephalitis, sensory neuronopathy | Anti-Hu (ANNA-1) | Small cell lung cancer | Neuronal nuclei; dorsal root ganglia |
| Anti-NMDA receptor encephalitis | Anti-NMDAR | Ovarian teratoma | Synaptic NMDA receptors |
| Opsoclonus-myoclonus | Anti-Ri; often none in children | Neuroblastoma (children), breast, lung | Brainstem and cerebellum |
| Lambert-Eaton myasthenic syndrome | Anti-VGCC (P/Q type) | Small cell lung cancer | Presynaptic calcium channels |
| Stiff-person syndrome | Anti-amphiphysin | Breast | Inhibitory synapses |
Clinical notes
- Brain metastases cause headache, seizures and focal deficits; single lesions may be resected or treated with radiosurgery.
- A new paraneoplastic syndrome should prompt a search for the hidden tumour; treating the tumour can help the syndrome.
Test yourself
Think of the answer, then tap the question to see it.
Where in the brain do metastases usually lodge?
At the junction of grey and white matter, where vessels narrow and tumour cells are trapped.
Which tumour is classically associated with anti-NMDA receptor encephalitis?
Ovarian teratoma, usually in young women.
Which antibody and tumour cause paraneoplastic cerebellar degeneration?
Anti-Yo antibodies with ovarian or breast cancer, destroying Purkinje cells.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Metastatic brain tumor: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.