Pathology of brain tumours Flashcards
What are the main causes of raised intracranial pressure?
Space occupying (localized lesions):
- Bleeding - Haemorrhage (Haematoma if localized)
- Tumour
- Abscess
Generalized pathology such as:
- Cerebral oedema post-trauma
Space occupying lesions can cause the brain to shift (herniate) within the skull
What are the types of herniation?
Cingulate
Central
Uncal
Cerebellotonsilar
Upward
Transcalvarial
Identify the types of brain herniation on the diagram below
What is a subfalcine herniation?
when brain tissue is displaced under the falx cerebri - the fold of dura mater down the longitudinal fissure
The cingulate herniation is a Subfalcine herniation
What is the effect of cerebellar tonsillar herniation?
Brainstem death
What are the structures indicated by red arrows?
Falx cerebri (top)
Tentorium cerebelli (bottom 2)
How can tumours cause ischaemia of brain tissue?
Tumours squeeze nearby tissue and cause local ischaemia
Describe the signs & symptoms associated with rising intracranial pressure
Morning headaches & sickness - Squeezing of cortex & brainstem
Papilloedema - Squeezing of Optic nerve
*At very high ICPs:*
Pupillary dilation - Squeezing of CN III
Falling GCS score - “ “ Cortex & brainstem
Brainstem death - Uncal/Cerebellotonsillar herniation through the foramen magnum
Aside from primary and secondary (metastasis) tumours of the CNS - how else can intracranial tumours form?
Tumours that arise from Cells originating outside brain and spinal cord (eg meningioma) - but are still within the cranium
Primary intracranial tumours are classed depending on their cells of origin
Glial cells – gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
Embryonic neural cells – medulloblastoma
Arachnoidal cell – meningioma
Nerve sheath cell – Schwannoma, neurofibroma
Pituitary gland - adenoma
Lymphoid cell – lymphoma
Capillary vessels - haemangioblastoma
What are the types of tumour that arise from/in brain tissue?
Gliomas (glial cell tumours):
- glioblastoma
- astrocytoma
- oligodendroglioma
- ependymoma
Medulloblastoma (embryonic neural cell tumour)
What types of intracranial tumours originate from cells surrounding or outside the brain?
Meningiomas - arachnoidal cell tumour
Schwannoma, neurofibroma - Nerve sheath cells
Adenomas - pituitary gland tumour
Lymphoma - lymphoid cell tumour
Haemangioblastoma - Capillary vessel tumour
What types of intracranial tumours are malignant (cancerous)?
All gliomas:
- Glioblastoma
- Astrocytoma
- Oligodendroglioma
- Ependymoma
Medulloblastoma - Childhood malignant tumour
As a general rule - how does the location of tumours tend to differ in adults and children?
Adults - above tentorium
Children - below tentorium
What cells give rise to each type of glioma?
Astrocytes –> astrocytoma (including glioblastoma)
Oligodendrocytes –> oligodendroglioma
Ependymal cells –> Ependyomas
Are gliomas able to metastasize?
Yep - but do not metastasise outside the CNS
Are gliomas encapsulated or non-encapsulated?
Non-encapsulated
Gliomas have diffuse edges
There are lots of types of astrocytoma - however - what are the 2 main types?
Low-grade astrocytoma:
- Slow growing, least malignant
Glioblastoma:
- Fast-growing, most malignant
- Often presents as large tumour
- Necrosis around tumour
How do the 2 main types of astrocytoma differ under a microscope?
Low-grade astrocytoma:
- Cells look a lot like normal astrocytes
- (Small star-like cells with one nucleus)
- Grow slowly
Glioblastoma:
- Cellular, atypical tumour - with necrosis
- Cells have multiple nuclei or wonky shaped nuclei
- Fast-growing
What type of tumour is shown here?
Meningioma
What is a medulloblastoma?
A tumour of the primitive neuroectoderm (primitive neural cells)
Affects children & sometimes adults
Sheets of undifferentiated cells
Tumours are found in the posterior fossa - commonly in/around the brainstem
What is a meningioma?
A Benign tumour that forms in the meninges - specifically from the arachnocytes around the brain
It is slow-growing but can be locally aggressive - and can directly invade the skull
Often resectable
Where are meningiomas found?
In the meninges - typically around the brain
Only a small proportion of meningiomas are in the spinal cord
They can also be found in places they directly invade - ie the Skull
What has caused the lesion shown here?
The meningioma has caused a depression in the cerebral hemisphere
Describe what microscopy of a meningioma would show
Microscopy will show bland cells forming small groups
± calcification (which is sometimes called a psammoma)
What are the types of nerve sheath tumours?
Schwannoma - of Schwann cells in the PNS
Oligodendroglioma - of O.cytes in the CNS
What is an Acoustic neuroma?
A very specific type of Schwannoma
Schwannoma of the Vestibularcochlear (CN VIII) nerve - located at the cerebellopontine angle
Although it is benign - it is difficult to resect
Acoustic neuroma causes unilateral deafness
What type of tumour is circled?
What are the arrows pointing to?
An acoustic neuroma (a type of schwannoma)
The arrows point to the cerebellum - the right is pretty wilted
What is this ting
Pituitary adenoma
Funnily enough, it comes from the pituitary glands
Large well-circumscribed mass protruding upwards from base of skull
What type of cells are most commonly associated with CNS lymphoma?
Usually diffuse large B-cell lymphoma
High-grade neoplasm
Why is it difficult to biopsy CNS lymphoma?
Lymphoma is often deep and central in the brain
Thus It is hard to reach for biopsy
It also does not typically spread out from the CNS
Why is it difficult to treat CNS lymphoma?
The drugs can’t cross the blood-brain barrier
What is a haemangioblastoma?
A tumour that arises in the capillaries in the brain - most commonly in the cerebellum
They are space-occupying (thus may restrict blood flow) - and may bleed (Haematoma etc etc)
What is the most common type of secondary tumour found in the brain?
Carcinomas
Commonly from the lungs, breast, kidneys…
This is fairly common in adults- but secondary tumours rare in children
