Pathology of Brain Tumours

Question 1

What is the differential diagnosis of raised ICP?

Answer 1

Localised lesions: ie.

• Haemorrhage (haematoma if localised)
• Tumour
• Abscess

Generalised pathology: ie.
- Oedema post-trauma

Question 2

What are the effects of Space Occupying Lesions (SOL) in the brain?

Answer 2

• Shift from R-L or L-R (under the falx cerebri)
• > midline shift (subfalcine herniation)
• > brain pushed away from the lesion
• > SOL squeezes nearby tissue -> localised ischaemia
• Cerebrum moves inferiorly over the edge of the tentorium
• > “uncal” or “tentorial herniation” of temporal lobe over the tentorium cerebelli
• Cerebellum moves inferiorly through the foramen magnum (coning)
• > “cerebellotonsilar herniation” or “coning”: of brainstem through the foramen magnum

Question 3

What are the clinical features of raised ICP?

Answer 3

• Squeeze on Cortex and Brainstem -> morning headaches and sickness
• Squeeze on Optic Nerve -> papilloedema (seen on fundoscopy of the eye )

Question 4

What are the different types of CNS primary tumours?

Answer 4

• Glial cells: Gliomas
• Embryonic neural cells: Medulloblastoma
• Arachnoidal cells: Meningioma
• Nerve sheath cells: Schwannoma, Neurofibroma
• Pituitary gland: Adenoma
• Lymphoid cell: Lymphoma
• Capillary vessels: Haemangioblastoma

Question 5

Which tumours frequently metastasise to the brain?

Answer 5

• Brain
• Lung
• Kidney
• Colon
• Melanoma

Question 6

What is Glioblastoma multiforme?

Answer 6

• Most malignant Astrocytoma
• fast-growing and aggressive -> often present as large tumours
• Microscopy: cellular, atypical cells

Question 7

What are the key features of Gliomas?

Answer 7

• Diffuse edges - not encapsulated

- Malignant - but does not metastasise out of the CNS

Question 8

What are the key features of Astrocytomas?

Answer 8

• Low grade tumours
• v slow growing
• Microscopy: look similar to normal astrocytes

Question 9

What are the key features of Medulloblastomas?

Answer 9

• Tumour of primitive neurectoderm (primitive neural cells)
• Sheets of small undifferentiated cells
• Esp. in children
• Posterior Fossa - esp. brainstem

Question 10

What are the key features of Meningiomas?

Answer 10

• From “arachnocytes” - cells that make up the coverings of the brain
• “Benign” - do not metastasise, but can be locally aggressive and invade the skull
• Slow-growing
• Often resectable
• Microscopy: bland cells forming small groups, sometimes with calcification (psammoma body)

Question 11

What are they key features of Acoustic Neuromas?

Answer 11

• 8th CN (Vestibulocochlear nerve) Schwannoma
• at angle between Pons and Cerebellum
• Unilateral deafness
• Benign (but technically difficult to remove)

Question 12

What are they key features of Pituitary Adenomas?

Answer 12

• Benign tumour of pituitary in pituitary fossa
• Often secretes pituitary hormone
• Grows superiorly and impinges on the Optic chiasm -> visual signs

Question 13

What are they key features of CNS Lymphomas?

Answer 13

• High-grade neoplasms
• Usually diffuse large B-cell Lymphomas
• Often deep and central site in the brain
• > difficult to biopsy
• Generally do not spread outside of the CNS

Question 14

What are they key features of Haemangioblastomas?

Answer 14

• Tumour of blood vessels
• Space occupying
• May bleed
• Most often in the Cerebellum