Pathology of brain tumours

Question 1

What leads to an increase in ICP

Answer 1

• Tumours
• Abcesses
• Hemorrage

Question 2

How is there an increase in ICP

Answer 2

-Increase of substance in the brain
-This causes the brain to shift intracranially- herniate
-There are 3 main types of herniation:
coning
uncal
Subfalcine

Question 3

What is coning herniation

Answer 3

Cerebrum moves inferiorly into the foramen magnum
Cause of brainstem death
Cerebral tonsils move downwards and crush brainstem

Question 4

What is uncle herniation

Answer 4

Cerebrum moves over the edge of the tentorium cerebella

Cerebral aqueduct is crushed

Question 5

What is subfalcine herniation

Answer 5

Midline drifts
Cingulate gyrus is crushed down and pushed under the falx
Lateral ventricle is pushed down and crushed

Question 6

What happens when the ICP increases

Answer 6

• Pupil dilation: as cranial nerve 3 is squeezed
• Decrease in GCS: due to squeezing of cortex
• Brainstem death: due to squeezing of cerebral tonsils on the spinal cord

Question 7

What are the two main types of brain tumour which can present?

Answer 7

• Primary- can be benign or malignant

- Secondary-metastatic often from breast, melanoma, kidney, colon

Question 8

Gliomas different types

Answer 8

resemble the type of cell they derive from:

• Astrocytomas
• Glioblastomas
• Oligodendriglioma
• Ependymoma

Question 9

General properties of astrocytomas

Answer 9

• Have diffuse edges

- Are malignant - but tend to not spread outside of CNS

Question 10

Differences between astrocytomas and glioblastomas

Answer 10

Low grade astrocytomas:

• slow growing
• Bland cell: small with small nucleus

Glioblastoma

• Fast growing: usually present as large tumour
• Present with necrosis under tissue under microscope
• Large cell with abnormal nucleus

Question 11

Properties of medullablastomas

Answer 11

• From embryonic neural cell
• Mainly malignant in children
• Affects the posterior fossa and the brainstem
• Undifferentiated cells arranged in sheets

Question 12

Properties of meningiomas

Answer 12

• From Arachnoid cells- Make up the sheets which cover the brain (meninges)
• Usually benign and do not metastasise- though can aggressively invade the brain
• Slow growing
• Oftern resectable
• On microscopy seen as bland cells which form small groups which encircle each other
• They often present with calcification: sometimes called psammoma
• They look like arachnoid granulations

Question 13

Nerve sheath tumours properties

Answer 13

Found around peripheral nerves both intracranially and extracranially
-Schwannomas

Question 14

Important example of a schwannoma

Answer 14

CN 8
Found at corner between the pons and the cerebellum
Causes unilateral deafness
Benign lesion but removal is difficult

Question 15

Pituitary adenoma

Answer 15

Benign tumour of the pituitary found in the pituitary fossa
Often secretes pituitary hormone
Can grow and compress on optic chasm causing vision loss

Question 16

CNS lymphoma

Answer 16

• High grade neoplasm
• Often large B cell lymphoma
• Difficult to treat as drugs cannot cross BBB
• Usually does not spread out of CNS

Question 17

Hemangioblastoma

Answer 17

• Tumour of blood vessels

- Most common in the cerebellum

Question 18

Properties of the cranium

Answer 18

• Very rigid cage of skull
• Brain tissue kept in place by rigid fibrous sheets: falx cerebrum and tentorium Cerebelli
• Opening into the spinal cord through the foramen magnum
• Brain cannot go through the falx cerebrum but can go around it
• Brain cannot go through skull but it can go down through foramen magnum