Pathology of Brain Tumours Flashcards
What is the main pathology of brain tumours?
Raised intracranial pressure
What is the cranium?
Hard, rigid box with thick fibrous sheets inside that keeps the brain in place
What are the thick fibrous sheets in the cranium called?
- Falx cerebri
- Tentorium cerebelli
What is the opening in the cranium called for the spinal cord?
Foramen magnum
What happens to the brain during extreme raised ICP?
The brain cannot go through the falx, but can go around the edge, it can not go through the skull, but can move down through the foramen magnum
Is the brain mobile?
Brain is soft, like a jelly, so it moves easily
What are some causes of raised intracranial pressure?
- Localised lesions
- Haemorrhage (if localised called a haematoma)
- Tumour
- Abscess
- Generalised pathology
- Oedema post trauma
What are localised lesions that cause raised intracranial pressure?
Space occupying lesions (SOL)
What does SOL stand for?
Space occupying lesiosn
What are examples of SOH?
- Tumours
- Bleeding (haematoma)
- Abscess
What are effects of 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 (uncul herniation)
- Cerebellum moves inferiorly into foramen magnum (coning)
What is coning?
Cerebellum moves inferiorly into foramen magnum
What is uncul hernation?
Cerebrum moves inferiorly over edge of tentorium
What is a haematoma?
Solid swelling of clotted blood within tissues
What are the different types of brain herniation?
What kind of shift does subfalcine herniation cause?
Subfalcine herniation causes midline shift:
- Brian is pushed away from tumour
- Cingulate gyrus is pushed over to side and herniates underneath falx
- Lateral ventricle is crushed flat and displaced downwards
What does tentorial (uncal) herniation cause?
- Brain herniates inferiorly at side of tentorium
- Aqueduct is crushed and narrow
What does cerebellar tonsillar herniation cause?
Cerebellar tonsillar herniation causes death of brain stem due to tonsils moving inwards and downwards, crushing the brainstem
Swelling and shift causes localised ischaemia due to tumours squeezing nearby tissue
What is the presentation of pressure on the brain?
Squeeze on cortex and brainstem:
- Morning headaches and sickness
Squeeze on optic nerve:
- Papilloedema (seen on fundoscopy of the eye)
As pressure increases:
- Pupillary dilation
- Squeeze and stretch on cranial nerve III
- Falling Glasgow coma scale
- Squeeze on cortex and brainstem
- Brain stem death
- Squeezing downwards of cerebellum into foramen magnum with crushing of brainstem
What symptoms does squeeze on the cortex and brainstem cause?
- Morning headaches and sickness
What symptoms does squeeze on optic nerve cause?
- Papilloedema (seen on fundoscopy of the eye)
What is the presentation as pressure on the brain increases?
- Pupillary dilation
- Squeeze and stretch on cranial nerve III
- Falling Glasgow coma scale
- Squeeze on cortex and brainstem
- Brain stem death
- Squeezing downwards of cerebellum into foramen magnum with crushing of brainstem
What are the two broad categories of CNS tumours?
- Primary tumours
- Secondary (metastatic) tumours
Are primary CNS tumours benign or malignant?
Some are benign and some are malignant
What are examples of primary CNS tumours?
- Glial cells
- Gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma) (malignant)
- Embryonic neural cells
- Medulloblastoma (childhood malignant tumour)
- Arachnoidal cell
- Meningioma
- Nerve sheath cell
- Schwannoma, neurofibroma
- Pituitary gland
- Adenoma
- Lymphoid cell
- Lymphoma
- Capillary vessels
- Haemangioblastoma
What are tumours of glial cells called?
Gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
What are different kinds of gliomas?
Glioblastoma, astrocytoma, oligodendroglioma, ependymoma
Are gliomas benign or malignant?
Malignant
What are tumours of embryonic neural cells called?
Medulloblastoma
Are medulloblastomas benign or malignant
What are tumours of arachnoidal cells called?
Meningioma
What are tumours of nerve sheath cells called?
- Schwannoma, neurofibroma
What are tumours of the pituitary gland called?
Adenoma
What are tumours of lymphoid cells called?
Lymphoma
What are tumours of capillary vessels called?
- Haemangioblastoma
What are tumours originating inside of the brain?
- Glial cells
- Gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma) (malignant)
- Embryonic neural cells
- Medulloblastoma (childhood malignant tumour)
What are primary CNS tumours originating outside of the brain?
- Arachnoidal cell
- Meningioma
- Nerve sheath cell
- Schwannoma, neurofibroma
- Pituitary gland
- Adenoma
- Lymphoid cell
- Lymphoma
- Capillary vessels
- Haemangioblastoma
Is metastatic malignancy to the CNS rare in children or adults?
Children
What are cancers that commonly metastasis to the CNS?
- Breast
- Lung
- Kidney
- Colon
- Melanoma
Why are nerve cell cancers rare?
Nerve cell cancers are rare as they do not proliferate due to being attached to far away things by axons and dendrites, only primitive neurons form tumours such as those in children
What is the tentoirum?
Extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes
In adults, are most cancers above or below the tentorium?
Above
In children, are most cancers above or below the tentorium?
Below
What do gliomas resemble?
Resemble cells of glial differentiation:
- Diffuse edges (not encapsulated)
- Malignant but do not metastasise outside the CNS (cannot get past the blood brain barrier)
Do gliomas metastasis outside of the CNS?
- Malignant but do not metastasise outside the CNS (cannot get past the blood brain barrier)
What are examples of gliomas?
- Astrocytes cause astrocytoma (including glioblastoma)
- Oligodendrocytes cause oligodendroglioma
- Ependymal cause ependymoma
What is cancer of astrocytes called?
- Astrocytes cause astrocytoma (including glioblastoma)
What is cancer of oligodendrocytes called?
Oligodendroglioma
What is cancer of ependymal cells called?
Ependymoma
What are glioblastomas?
Glioblastoma is a very malignant version of oligodendroglioma
What is the shape of astrocytes?
Star shaped
What do the long processes of astrocytes do?
Support other cells structurally and biochemically
What are the different types of astrocytoma?
- Low grade astrocytoma
- Bland cells on microscopy (similar to normal astrocytes)
- Grow very slowly
- Small cells with single nucleus
- Glioblastoma (also known as a high grade astrocytoma)
- Cellular, atypical tumour, with necrosis under microscope
- Grow quickly, often presenting as large tumour
- Large cell with multiple nuclei, or large cell with irregular nucleus
Compare the growth of low grade astrocytoma and glioblastoma?
Low grade - grow very slowly
High grade - grows quickly, often presenting as a large tumour
Describe the morphology of low grade and high grade astrocytoma?
Low grade - small cells with single nucleus
High grade - large cell with multiple nuclie, or lage cell with irregular nucleus
Describe how low grade and high grade astrocytoma?
Low grade - bland cells on microscopy
High grade - cellular, atypical tumour, with necrosis
What is glioblastoma also called?
High grade astrocytoma
What is medulloblastoma?
Tumour of primitive neuroectoderm (primitive neural cells):
- Sheets of small undifferentiated cells
- Children especially
- Posterior fossa, especially brainstem
What does medulloblastoma present as?
Presents as morning headache gradually getting worse over 6 months
Is menginioma benign or malignant?
Benign, but can be locally aggressive and invade the skull
Are meningioma slow growing or fast growing?
Slow growing, often resectable
Why can meningioma have no symptoms?
May not have many symptoms due to causing depressions in the brain slowly, but can develop symptoms as gets bigger
What is seen in microscopy of meningioma?
- Bland cells forming small groups, sometimes with calcification
- Small groups of cells whirl around each other resembling an arachnoid granulation
- Calcification is sometimes called psammoma
Where do nerve sheath tumours occur?
Around peripheral nerves (intracranial and extracranial)
What is ‘acoustic neuroma’?
- 8th vestibulocochlear nerve schwannoma often called ‘acoustic neuroma’ at angle between pons and cerebellum
- Unilateral deafness
- Benign lesion but removal technically difficult
What does pituitary adenoma often secrete?
A pituitary hormone
What can be a consequence of pituitary adenoma due to growth?
Grow superiorly and impinge on optic chiasma, causing visual signs
What is CNS lymphoma?
High grade neoplasm
Usually diffuse large B-cell lymphoma
Is CNS lymphoma usually T cell or B cell?
Usually diffuse large B-cell lymphoma
Why is CNS lymphoma often difficult to biopsy?
Often deep and central site in brain
Why is CNS lymphoma difficult to treat with drugs?
Difficult to treat as drugs do not cross the blood brain barrier
Does CNS lymphoma metastasis outside of CNS?
Generally do not spread outside of CNS
What is haemangioblastoma?
Tumour of blood vessels
Where does haemangioblastoma often occur?
Most often in cerebellum
What are consequences of haemangioblastoma?
Space occupying
May bleed
What is the histology of a secondary tumour?
That of the primary tumour
