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Cerebral metastasis

Summary

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  • Cerebral metastases are secondary brain tumours originating from primary cancers elsewhere in the body
  • Most common in lung cancer, breast cancer, and melanoma patients
  • Typically present with neurological symptoms, headaches, and seizures

Pathophysiology

  • Metastatic spread occurs via:
    • Hematogenous dissemination (most common)
    • Direct extension from adjacent structures
    • Lymphatic spread (rare)
  • Tumour cells breach the blood-brain barrier and proliferate in brain parenchyma
  • Growth factors and angiogenesis promote tumour expansion

Demographics

  • Incidence:
    • 20-40% of cancer patients develop brain metastases
    • Increasing due to improved systemic therapies and longer patient survival
  • Most common primary sites:
    • Lung cancer (40-50%)
    • Breast cancer (15-25%)
    • Melanoma (5-20%)
    • Colorectal cancer (5-10%)
    • Renal cell carcinoma (5-10%)

Diagnosis

  • Clinical presentation:
    • Headache (40-50%)
    • Focal neurological deficits (20-40%)
    • Cognitive changes (30-35%)
    • Seizures (10-20%)
  • Diagnostic workup:
    • Neurological examination
    • Contrast-enhanced MRI (gold standard)
    • CT scan (if MRI contraindicated)
    • Biopsy (if primary cancer unknown or atypical presentation)

Imaging

  • MRI findings:
    • T1-weighted: iso- to hypointense lesions
    • T2-weighted: iso- to hyperintense lesions
    • T1 post-contrast: ring-enhancing or nodular enhancement
    • Surrounding vasogenic oedema on T2/FLAIR
  • CT findings:
    • Hypodense or isodense lesions
    • Heterogeneous enhancement with contrast
    • Calcifications (rare)
  • Advanced imaging techniques:
    • Perfusion imaging: increased relative cerebral blood volume
    • Spectroscopy: elevated choline, reduced N-acetylaspartate

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  • A 60-year-old patient presented with right sided weakness.
  • MRI showed a ring-enhancing lesion near grey-white matter interface with surrounding vasogenic oedema.

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  • A 80-year-old patient with a history of bladder cancer presented with headche.
  • Imaging showed a peripherally enhancing lesion containing blood product in the left frontal lobe with a large volume of surrounding vasogenic oedema.

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  • A 60-year-old patient who was diagnosed with colonic cancer three years prior presented with a right visual field defect and headache.
  • A large left occipital lobe lesion showed peripheral enhancement and was surrounded by vasogenic oedema.
  • The peripheral T2-hypointensity within the lesion has been reported to be related to collagen accumulation.

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  • A 70-year-old patient with small cell lung cancer presented with right leg weakness.
  • MRI showed many peripherally enhancing lesions, the larges of which was in the left paracentral lobule.
  • Following chemotherapy, MRI showed a marked reduction in the size of all of the lesions and the surrounding oedema.

panels-1 * 70-year-old patient with a new diagnosis of non-small cell lung cancer had an MRI to 'screen' for metastasis. * MRI showed subcentrimeter ring-enhancing lesions with variable amounts of surrounding vasogenic oedema.

Treatment

  • Multidisciplinary approach:
    • Neurosurgery
    • Radiation oncology
    • Medical oncology
  • Treatment options:
    • Surgical resection:
    • For accessible, large (>3 cm) solitary lesions
    • Improves local control and survival
    • Stereotactic radiosurgery (SRS):
    • For small (<3 cm) or multiple lesions
    • High-dose, focused radiation
    • Whole-brain radiation therapy (WBRT):
    • For multiple lesions or leptomeningeal disease
    • Associated with cognitive decline
    • Systemic therapy:
    • Chemotherapy
    • Targeted therapies (e.g., EGFR inhibitors for lung cancer)
    • Immunotherapy (e.g., checkpoint inhibitors for melanoma)
  • Supportive care:
    • Corticosteroids for oedema management
    • Anticonvulsants for seizure control
    • Pain management

Differential diagnosis

Differential Diagnosis Differentiating Feature
Primary brain tumour (high-grade glioma) Usually single lesion with infiltrative margins crossing white matter tracts; no grey-white junction predilection
Cerebral abscess Thin smooth ring enhancement with restricted diffusion centrally; may have satellite lesions
Multiple sclerosis Ovoid periventricular lesions, often with "Dawson's fingers" on sagittal FLAIR; no surrounding vasogenic oedema
Cerebral infarction Follows vascular territory; wedge-shaped; diffusion restriction in acute phase; cortical gyral enhancement
Glioblastoma Single lesion with central necrosis and irregular ring enhancement; crosses corpus callosum; more infiltrative margins
Lymphoma Periventricular location; homogeneous enhancement; restricted diffusion; hyperdense on non-contrast CT
Toxoplasmosis Multiple ring-enhancing lesions; basal ganglia predilection; eccentric nodule ("target sign")
Radiation necrosis Located within prior radiation field; identical ring enhancement; MR perfusion/spectroscopy may help distinguish
Neurocysticercosis Cystic lesions with eccentric scolex nodule; perilesional calcification; no grey-white junction predilection
Tuberculoma Conglomerate ring-enhancing lesions; central T2 hypointensity; leptomeningeal enhancement