Pathology of Brain Tumours Flashcards
What determines intracranial pressure?
Brain tissue
Blood
CSF
How can the brain move with relation to the falx cerebri and the foramen magnum?
Brain cannot go through the falx but can go round the edge
Brain cannot go through the skull but can move down through the foramen magnum
What are causes of raised intracranial pressure?
Haemorrhage
Tumour
Abscess
Generalised pathology (e.g - oedema)
What are the SOL? (space occupying lesions)
Tumours
Bleeding
Abscess
What is the effect of an intracranial space occupying lesion?
Increase in tissue
Increase in intracranial pressure
Internal herniation between the intracranial spaces:
Cerebrum moves inferiorly over the edge of tentorium (uncal herniation)
Cerebellum moves inferiorly into foramen magnum (coning)
What is subfalcine herniation?
Cingulate gyrus herniates underneath falx
Lateral ventricle is crushed flat and is displaced downwards
What is uncal herniation?
Brain herniates inferiorly at side of tentorium
Aqueduct is crushed and narrow
What is the cause of brainstem death?
Cerebellar tonsillar herniation
Tonsils move inwards an downwards and crush the brainstem
What is the effect of swelling on blood supply?
Tumours squeeze nearby tissue and cause local ischaemia
What are the symptoms of raised intracranial pressure?
Morning headaches and sickness as a result of squeeze on the cortex and the brainstem
Papilloedema (optic disk swelling) - squeeze on optic nerve
Why do the pupils dilate during raised intracranial pressure?
Squeeze and stretch on cranial nerve 3
Why is there a fall on the glasgow coma scale during an increase in the intracranial pressure?
There is a squeeze on the cortex and the brainstem
To recap pressure increase results in?
Pupillary dilation
Falling glasgow coma scale
Brainstem death
What are the classifications of intracranial tumours?
Primary tumours
Secondary tumours (metastatic tumours)
Other intracranial tumours (cells originating outside the brain and the spinal cord (eg meningioma))
What are the types of primary intracranial tumours that arise from brain cells?
Glial cells - gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
Embryonic neural cells: medulloblastoma
What are the primary brain tumours that arise from cells surrounding or originating outside the brain?
Arachnoidal cell - meningioma
Nerve sheath cell - schwannoma, neurofibroma
Pituitary gland - adenoma
Lymphoid cell - lymphoma
Capillary vessel - haemangioblastoma
For intradural think of LEMON (LMN)
Lipoma
Meningioma
Neurofibroma
For intramedullary think HEAT:
Haemangioblastoma
Ependymoma
Astrocytoma
Teratoma
What is the childhood malignant tumour?
Medulloblastoma
Where are the central nervous system tumours for adults and children?
Adults - majority are above the tentorium
Children - majority are below the tentorium
What are the features of a glioma?
Resembles cells of glial differentiation
Difuse edges - not encapsulated
Malignant but do not metastasise outside the CNS
Where does metastatic malignancy in the brain arise from?
Breast
Lung
Kidney
Colon
Melanoma
What cells do gliomas resemble?
The cells of glial differentiation
Astrocytes - astrocytoma - including glioblastoma
Oligodendrocytes - oligodendroglima
Ependymal cells - ependymoma
What is an example of an astrocytoma?
Glioblastoma
What is the shape of an astrocyte?
Star shaped cell
What are the features of astrocytomas?
Bland cells on microscopy (similar to normal astrocytes)
Grow very slowly
Small cell with single nucleus
What is the most malignant?
Glioblastoma - not to be confused with low grade astrocytoma as described previously
What are the features of glioblastoma?
Cellular, atypical tumour with necrosis under the microscope
Grow quickly - often present as large tumours
LARGE CELL WITH MULTIPLE NUCLEI
LARGE CELL WITH IRREGULAR NUCLEUS
What is the medulloblastoma a tumour of?
It is a tumour of the primitive neuroectoderm (primitive neural cells)
What are the features of medulloblastoma?
Sheets of small undiferentiated cells
Affects children especially
Situated in the posterior fossa, especially the brainstem
What forms from arachnocytes?
Meningiomas
Arachnocytes are cells tha make up the covering of the brain
Where can you find meningiomas?
They are benign and do not metastasise but can be locally aggressive and can invade the skull
What are the features of meningiomas?
Slow growing
Often resectable
Small groups of cells gather and resemble an arachnoid granulation
Sometimes the cells calcify
The calcification is sometimes called psammoma meaning grain of sand
Where can you find nerve sheath tumours?
Intracranial and extracranial
Give an example of a schwannoma
8th vestibulocochlear nerve schwannoma - often called acoustic neuroma - found at the angle between the pons and the cerebellum
What are the features of an acoustic neuroma?
Unilateral deafness
Benign lesion but removal is difficult
Is a pituitary tumour benign or malignant?
Benign
Tumour of the pituitary in the pituitary fossa
What are the features of a pituitary tumour?
Often secrete pituitary hormone
Grow superiorly and impinge on optic chiasma - visual signs (bitemporal hemianopia)
What type of cell makes up a CNS lymphoma usually?
Usually large B-Cell lymphoma
Where in the brain do you find CNS lymphomas?
Often deep and central site in the brain
They generally do not spread outside of the CNS
Why are CNS lymphomas hard to treat?
Drugs do not cross the blood rbain barrier and they are difficult to biopsy
What are the complications associated with haemangioblastoma?
May bleed
Where do you find haemangioblastomas?
Most often in the cerebellum
What are the features of secondary tumours?
Mostly carcinomas
Common
Histology - that of the primary tumour
Learning objectives
- Demonstrate understanding of raised intracranial pressure
- Know symptoms/signs/consequences of raised intracranial pressure
- Classify intracranial neoplasms
- Concentrate initial learning on astrocytoma (including glioblastoma) /meningioma/schwannoma and pituitary adenoma
