Space-Occupying Lesions
What general effect do space-occupying lesions have on brain tissue?
They raise intracranial pressure (ICP) by compressing or displacing brain tissue.
Name one early morning symptom typical of raised ICP.
Headache
Which tumour arises from the meninges?
Meningioma
What is the cell of origin for gliomas?
Glial cells (astrocytes, oligodendrocytes, etc.)
What is the median survival for glioblastoma after diagnosis?
~14–15 months
Which clinical sign of raised ICP results from compression of the optic nerve head?
Papilloedema
What age group is most affected by infratentorial tumours?
Children
Which primary malignant brain tumour is most common in adults?
Glioblastoma multiforme
What histological features are used to assign WHO tumour grade?
Pleomorphism, mitoses, microvascular proliferation, and necrosis
Which drug is the standard chemotherapeutic for glioblastoma?
Temozolomide
What is Cushing’s triad and why does it occur?
Bradycardia, hypertension, irregular respiration — a reflex response to raised ICP and brainstem compression.
How do symptoms differ between a grade 2 and a grade 4 astrocytoma?
Grade 2 has long history, seizures, mild symptoms;
grade 4 (glioblastoma) has rapid progression and severe ICP symptoms.
Which tumours most commonly metastasize to the brain?
Lung, breast, and kidney cancers
Describe the appearance of glioblastoma under the microscope.
Pseudopalisading necrosis and microvascular proliferation
How does MGMT promoter methylation influence prognosis?
Methylation silences MGMT, reducing DNA repair → better response to temozolomide and improved survival.
What differentiates the symptoms of extrinsic vs intrinsic lesions?
Extrinsic → compression;
intrinsic → infiltration; both can raise ICP but intrinsic lesions cause focal neurological deficits.
Which symptom combination suggests late-stage intracranial hypertension?
Drowsiness, vomiting, and papilloedema (possibly with Cushing’s triad).
What type of tumour is most common in children and often infratentorial?
Pilocytic astrocytoma or medulloblastoma
Match the tumour: Grade 1 Pilocytic Astrocytoma – typical age and features.
Children/young adults; low proliferation, good prognosis, often curable with surgery.
Why might complete resection not be curative even for localised gliomas?
Gliomas are highly infiltrative, spreading microscopically beyond visible margins.
Explain why low-grade lesions may present with seizures rather than rapid neurological decline.
The brain accommodates slow growth and pressure rise, leading to cortical irritation rather than acute herniation.
Why might glioblastoma remain asymptomatic until late in progression?
Glioblastoma cells can form functional synapses with neurons, masking early functional disruption.
Explain why metastases often occur at the grey–white matter junction.
The region’s dense vasculature and abrupt vessel calibre changes trap circulating tumour emboli.
Why is predicting progression difficult in low-grade astrocytomas?
No reliable molecular biomarker; behaviour and progression are unpredictable despite histology.
Describe how tumour evolution follows a Darwinian model and why this complicates treatment.
Tumours develop multiple genetic subclones (branching evolution), leading to intra-tumour heterogeneity and therapy resistance.