Pathology of Brain Tumours Flashcards
(26 cards)
What are the two main tough fibrous sheets that keep the brain in place within the skull?
- Falx Cerebri
- Tentorium Cerebelli
Main causes of raised intracranial pressure?
Localized lesions:
- Haemorrhage
- Tumours
- Abscesses
(Oedema post trauma - generalized)
What effect can raised intracranial pressure have on the position of the brain in the skull?
Can cause herniation
Common types of cerebral herniation?
- Left-right/right-left (across falx)
- Uncal herniation (cerebrum moves below tentorium)
- Coning/Cerebellotonsilar (cerebellum and tonsils inferiorly into foramen magnum)
What is a subfalcine herniation?
Cause of raised ICP on one side of the falx cerebri, pushes the cingulate gyrus beneath the falx/falcine membrane to herniate the other side
- Falcine membrane also commonly laterally displaced
- Lateral ventricle on high ICP side crushed flat
What is a tentorial/uncal herniation?
Brain herniates inferiorly at the edge of the tentorium
- Cerebral aqueduct is crushed and narrow
What occurs during a cerebellar tonsillar herniation?
Cerebellar tonsils move inwards and inferiorly towards/through foramen magnum
- Crushes brainstem
Why is there sometimes an ischaemic zone around tumours in the brain?
Tumours squeeze and exert pressure on the nearby tissue, causing local ischaemia
Possible signs of raised intracranial pressure?
- Morning headaches and sickness
- Papilloedema (optic disc swelling, sometimes seen)
Clinical signs that intracranial pressure is increasing?
- Pupillary dilation (squeeze/stretch on CN III)
- Falling GCS
- Brain stem death (when tonsils move into foramen magnum)
Types of intracranial tumour?
- Primary
- Secondary (metastases)
- Other: from cells originating outside the brain and spinal cord (eg. meningioma)
Types of primary intracranial tumours?
By resemblance of cell of origin:
- Glial cells: gliomas (glioblastoma/astrocytoma etc.)
- Embryonic neural cells: medulloblastoma
- Arachnoidal cell: meningioma
- Nerve sheath cell: schwannoma, neurofibroma
- Pituitary gland: adenoma
- Lymphoid: lymphoma
- Capillary vessels: haemangioblastoma
Common origins of brain metastases?
- Breast
- Lung
- Kidney
- Colon
- Melanoma
who tends to get malignancies of the embryonic neural cells?
Tends to be a childhood malignant tumour
How do CNS tumours tend to differ between children and adults with regards to location?
- Adults: tumours tend to occur above the tentorium cerebelli
- Children: tumours usually below tentorium cerebelli
What are some characteristics of gliomas?
- Resemble glial cells most
- Diffuse edges, not encapsulated
- Malignant, but don’t metastasize outside the CNS
Examples of some types of gliomas?
Astrocytes - astrocytoma + glioblastoma
Oligodendrocytes - oligodendroglioma
Ependymal cells - ependymoma
Differences between astrocytoma and glioblastoma?
- Astrocytoma: slow growing, similar to astrocyte cells on microscopy, small cells w single nucleus
- Glioblastoma: fast growing, large cells sometimes w multiple nucleii, atypical tumour with necrosis under microscope
What does a medulloblastoma differentiate from? Characteristics?
- From primitive neuroectoderm
- Occurs in children especially
- Usually located in posterior fossa, often around brainstem
What cells do meningioma’s differentiate from? Characteristics of meningioma?
- Differentiate from cells that make up the meninges (“arachnocytes” in lecture)
- Are benign, do not metastasize but can locally invade the skull
- Slow growing and resectable
- Can resemble an arachnoid granulation under microscope: small group of cells around eachother
Where do nerve sheath tumours occur?
Around peripheral nerves
Originate from cells surrounding the nerves, eg. Schwannoma
What is an acoustic neuroma? Some characteristics and signs?
- Schwannoma of CN VIII
- Occurs at angle between pons and cerebellum
- Results in unilateral deafness (presses on other cranial nerves as tumour expands)
- Removal technically difficult due to location
Signs and characteristics of pituitary adenoma?
- Benign tumour, located in pituitary fossa
- May present with endocrine abnormalaties as tumour often secretes pituitary hormone
- May have visual impairment (bitemporal hemianopia) as tumour grows superiorly and impinges on optic chiasma
Characteristics of a CNS lymphoma?
- Often deep and central within the brain
- Difficult to treat as drugs don’t cross BBB
- Generally non-metastatic
