The Pathology of Intracranial Tumours Flashcards
Name four causes of raised intracranial pressure
Localised lesions:
• Haemorrhage (if localised called a haematoma)
• Tumour
• Abscess
Generalised pathology:
• Oedema post trauma
What is a SOL?
Intracranial space occupying lesions (localised lesions)
What are the effects of intracranial SOL?
• 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)
Name six types of brain herniation
- 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
What is a subfalcine herniation?
Midline shift where brain is pushed away from tumour
What are the anatomical changes that occur in a subfalcine herniation?
- 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
What is a tectorial herniation?
Uncal herniation where the brain herniates inferiorly at side of tentorium –> aqueduct is crushed and narrow
What happens in cerebellar tonsillar herniation?
Tonsils move inwards and downwards and crush the brainstem –> cause of brainstem death
Give examples of symptoms and signs of localised pressure on the brain
- Pressure on cortex and brainstem –> morning headaches and sickness
- Pressure on optic nerve –> papilloedema (seems on fundoscopy of eye)
What are the consequences of as intracranial pressure increases?
- 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
What are the different types of intracranial tumours?
- CNS: primary or secondary (metastatic) tumours
* Other: cells originating outside brain and spinal cord (i.e. meningioma)
Give examples of primary (benign and malignant) intracranial tumours
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)
Give examples of metastatic malignant intracranial tumours
- Breast
- Lung
- Kidney
- Colon
- Melanoma
How do the location of CNS tumour differ in children and in adults?
- Adults: majority above tentorium
* Children: majority below tentorium
Describe gliomas
Resemble cells of glial differentiation:
• Diffuse edges - not encapsulates
• Malignant but do not metastasise outside of CNS
How do gliomas resemble cells of glial differentiation?
- Astrocytes –> astrocytoma (including glioblastoma)
- Oligodendrocytes –> oligodendroglioma
- Ependymal cells –> ependymoma
Describe an astrocyte
Star shaped cell - long processes support other cells structurally and biochemically
What are two examples of astrocytomas?
- Low grade astrocytoma
- Glioblastoma (most malignant type)
(many others)
Describe a glioblastoma
- Cellular, atypical tumour, with necrosis under microscope
* Grow quickly - often present as large tumours
What is a medullablastoma?
Tumour of primitive neuroectoderm (primitive neural cells)
• Sheets of small undifferentiated cells
• Children especially
• Posterior fossa, especially brainstem
Describe meningiomas
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
Describe the microscopy of a meningioma
Shows bland cells forming small groups, sometime with calcifications (psammoma)
What are nerve sheath tumours?
- Around peripheral nerves - intracranial and extra cranial
- Schwannoma is an example
- Normal schwann cells wrap around peripheral nerve and form electrical insulation
Give an example of a schwannoma and its effects
8th vestibulocochlear nerve schwannoma, often called ‘Acoustic neuroma’ at angle between pons and cerebellum
• Unilateral deafness
• Benign lesion but removal technically difficult
Describe a pituitary adenoma
- Benign tumour of pituitary in pituitary fossa
- Often secrete a pituitary hormone
- Grow superiorly and impinge on optic chiasma – visual signs
What is a CNS lymphoma?
- 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
What is a haemangioblastoma?
Tumour of blood vessels
• Space occupying
• May bleed
• Most often in cerebellum
