The Pathology of Intracranial Tumours

Question 1

Name four causes of raised intracranial pressure

Answer 1

Localised lesions:
• Haemorrhage (if localised called a haematoma)
• Tumour
• Abscess

Generalised pathology:
• Oedema post trauma

Question 2

What is a SOL?

Answer 2

Intracranial space occupying lesions (localised lesions)

Question 3

What are the effects of intracranial SOL?

Answer 3

• Amount of tissue increases
• Raises intracranial pressure
• Cause internal shift (herniation) between the intracranial spaces
- Right-left or left-right
- Cerebrum moves inferiorly over edge of tentorium (uncle herniation)
- Cerebellum moves inferiorly into foramen magnum (coning)

Question 4

Name six types of brain herniation

Answer 4

• Cingulate - across falx cerebri
• Central - middle downwards
• Uncal - cortex through tentorium cerebelli
• Cerebellotonsilar
• Upward - push of brainstem down
• Transcalvarial - through skull fracture to outside skull

Question 5

What is a subfalcine herniation?

Answer 5

Midline shift where brain is pushed away from tumour

Question 6

What are the anatomical changes that occur in a subfalcine herniation?

Answer 6

• Falx pushed over to side
• Cingulate gyrus is pushed over to side and herniates underneath falx = subfalcine herniation
• Lateral ventricle is crushed flat and displaced downwards

Question 7

What is a tectorial herniation?

Answer 7

Uncal herniation where the brain herniates inferiorly at side of tentorium –> aqueduct is crushed and narrow

Question 8

What happens in cerebellar tonsillar herniation?

Answer 8

Tonsils move inwards and downwards and crush the brainstem –> cause of brainstem death

Question 9

Give examples of symptoms and signs of localised pressure on the brain

Answer 9

• Pressure on cortex and brainstem –> morning headaches and sickness
• Pressure on optic nerve –> papilloedema (seems on fundoscopy of eye)

Question 10

What are the consequences of as intracranial pressure increases?

Answer 10

• Pupillary dilation - squeeze and stretch on CN III
• Falling Glasgow Coma Scale - pressure on cortex and brainstem
• Brainstem death - pressure downwards of cerebellum into foramen magnum with crushing of brainstem

Question 11

What are the different types of intracranial tumours?

Answer 11

• CNS: primary or secondary (metastatic) tumours

* Other: cells originating outside brain and spinal cord (i.e. meningioma)

Question 12

Give examples of primary (benign and malignant) intracranial tumours

Answer 12

Brain cells:
• Glial cells – gliomas (glioblastoma, astrocytoma)
• Embryonic neural cells – medulloblastoma

Cells surrounding or originating outside brain:
• Arachnoidal cell – meningioma
• Nerve sheath cell – Schwannoma
• Pituitary gland - adenoma
(• Lymphoid cell – lymphoma
• Capillary vessels - haemangioblastoma)

Question 13

Give examples of metastatic malignant intracranial tumours

Answer 13

• Breast
• Lung
• Kidney
• Colon
• Melanoma

Question 14

How do the location of CNS tumour differ in children and in adults?

Answer 14

• Adults: majority above tentorium

* Children: majority below tentorium

Question 15

Describe gliomas

Answer 15

Resemble cells of glial differentiation:
• Diffuse edges - not encapsulates
• Malignant but do not metastasise outside of CNS

Question 16

How do gliomas resemble cells of glial differentiation?

Answer 16

• Astrocytes –> astrocytoma (including glioblastoma)
• Oligodendrocytes –> oligodendroglioma
• Ependymal cells –> ependymoma

Question 17

Describe an astrocyte

Answer 17

Star shaped cell - long processes support other cells structurally and biochemically

Question 18

What are two examples of astrocytomas?

Answer 18

• Low grade astrocytoma
• Glioblastoma (most malignant type)

(many others)

Question 19

Describe a glioblastoma

Answer 19

• Cellular, atypical tumour, with necrosis under microscope

* Grow quickly - often present as large tumours

Question 20

What is a medullablastoma?

Answer 20

Tumour of primitive neuroectoderm (primitive neural cells)
• Sheets of small undifferentiated cells
• Children especially
• Posterior fossa, especially brainstem

Question 21

Describe meningiomas

Answer 21

From arachnocytes – cells that make up the coverings of the brain

Benign – do not metastasise – but can be locally aggressive and can invade the skull

• Slow growing
• Often resectable

Question 22

Describe the microscopy of a meningioma

Answer 22

Shows bland cells forming small groups, sometime with calcifications (psammoma)

Question 23

What are nerve sheath tumours?

Answer 23

• Around peripheral nerves - intracranial and extra cranial
• Schwannoma is an example
• Normal schwann cells wrap around peripheral nerve and form electrical insulation

Question 24

Give an example of a schwannoma and its effects

Answer 24

8th vestibulocochlear nerve schwannoma, often called ‘Acoustic neuroma’ at angle between pons and cerebellum
• Unilateral deafness
• Benign lesion but removal technically difficult

Question 25

Describe a pituitary adenoma

Answer 25

• Benign tumour of pituitary in pituitary fossa
• Often secrete a pituitary hormone
• Grow superiorly and impinge on optic chiasma – visual signs

Question 26

What is a CNS lymphoma?

Answer 26

• High grade neoplasm
• Usually diffuse large B-cell lymphoma
• Often deep and central site in brain
• Difficult to biopsy
• Difficult to treat as drug do not cross blood-brain barrier
• Generally do not spread outside of CNS

Question 27

What is a haemangioblastoma?

Answer 27

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