The Pathology of intracranial tumours Flashcards
what is meant by intracranial pressure?
Cranium is a hard, rigid, closed box
For pressure to be stable must be (within certain limits) correct amount of brain tissue/blood/CSF
what must be considered anatomically in relation to intr cranial pressure?
There are thick tough fibrous sheets inside that keep the brain in place
Falx cerebri
Tentorium cerebelli
Opening to spinal cord
Foramen magnum
can brain go through the falx cerebri?
Brain cannot go through falx, but can go round edge
can brain go through the skull?
Brain cannot go through skull, but can move down through foramen magnum
what are localised lesion causes of raised intra-cranial pressure?
Haemorrhage (if localised called a haematoma)
Tumour
Abscess
what are generalised pathologies causing raised intra-cranial pressure?
Oedema post trauma
what are space occupying lesions in the head?
Tumours
Bleeding (haematoma)
Abscess
what effect do space occupying lesions have in the cranium?
Amount of tissue increases
Raises intra cranial pressure
Cause internal shift (herniation) between the intracranial spaces
how can the brain internally shift?
Right-left or left-right
Cerebrum moves inferiorly over edge of tentorium (uncal herniation)
Cerebellum moves inferiorly into foramen magnum (coning)
what is tentorial herniation?
Uncal herniation of temporal lobe over the tentorium
what is coning?
Cerebellotonsillar (‘tonsillar’) herniation of brain stem through foramen magnum
Subfalcine (= under falx) herniation =
midline shift
Falx (falcine membrane) 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 effect does swelling and shift have?
localised ischaemia
Tumours squeeze nearby tissue and cause local ischaemia
what symptoms and signs does squeeze on cortex and brainstem have?
morning headaches and sickness
what symptoms and signs does squeeze on optic nerve have?
papilloedema (seen on fundoscopy of eye)
as intra cranial pressure increases what signs can be seen?
Pupillary dilation
Falling Glasgow coma scale
Brain stem death
what is pupillary dilation caused by?
Squeeze and stretch on cranial nerve 3
what is a falling glasgow coma scale caused by?
Squeeze on cortex and brainstem
what is brain stem death caused by?
squeezing downwards of cerebellum into foramen magnum with crushing of brainstem (patient is dead)
what types of intracranial tumours are within the CNS?
Primary tumours
Secondary (metastatic tumours)
what intracranial tumours are not found within the CNS?
Cells originating outside brain and spinal cord (eg meningioma)
what are different types of primary intracranial tumours (benign and malignant)?
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
glial cells
gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
embryonic neural cells
medulloblastoma
arachnoudal cells
meningioma
Nerve sheath cell
Schwannoma, neurofibroma
Pituitary gland
adenoma
lymphoid cell
lymphoma
Capillary vessels
haemangioblastoma
what type of malignancy is common in adults but rare in children?
Metastatic malignancy
Breast, lung, kidney, colon, melanoma
which primary tumours are originated from brain cells?
Glial cells – gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
Embryonic neural cells – medulloblastoma
which primary tumours are originated from cells surrounding / outside the brain?
Arachnoidal cell – meningioma
Nerve sheath cell – Schwannoma, neurofibroma
Pituitary gland - adenoma
Lymphoid cell – lymphoma
Capillary vessels - haemangioblastoma
which primary tumours are classed as malignant tumours?
Glial cells – gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
which primary tumour is a type of childhood malignant tumour?
Embryonic neural cells – medulloblastoma
what is the location of CNS tumours in adults commonly?
Majority above tentorium
what is the location of CNS tumours in children commonly?
Majority below tentorium
how would you describe the diffuse edges of gliomas?
not encapsulated
how is the malignancy of gliomas described metastasise wise?
Malignant but do not metastasise outside the CNS
glial cells differentiate into…
astrocytoma
oligodendrocytes differentiate into…
oligodendroglioma
ependymal cells differentiate into…
ependymoma
what are the different tyoes of gliomas?
Astrocytoma (main type)
how is the shape of an astrocyte described?
‘Star’ shaped cell
Long processes support other cells
structurally and biochemically
what are the different types of extremes of astrocytoma?
Low grade astrocytoma
Glioblastoma
[3. Many others……..]
how are cells on microscopy described in low grade astrocytoma?
Bland cells on microscopy (similar to normal astrocytes)
Grow very slowly
small cells with single nucleus
how are cells on microscopy described in high grade astrocytoma
glioblastoma
large tumour with necrosis
what is a gliobastoma?
Cellular, atypical tumour, with necrosis under microscope
Grow quickly – often present as large tumours
Large cell with multiple nuclei / single nucleus
what is medulloblastoma?
Tumour of primitive neuroectoderm (primitive neural cells)
Sheets of small undifferentiated cells
Children especially
Posterior fossa, especially brainstem
what is meningioma?
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
what is the location of meningioma most commonly?
Meningioma is usually attached to the meninges and pushes into the brain but does not usually invade it
what does microscopy of a meningioma show?
Microscopy – bland cells forming small groups, sometimes with calcification
Small groups of cells whorl around each other, resembling an arachnoid granulation
The calcification is sometimes called a psammomabody (from ‘grain of sand’)
what are nerve sheath tumours?
Around peripheral nerves – intracranial and extracranial
what is an example of a nerve sheath tumour?
Schwannoma
how do normal schwann cells present?
Normal schwann cells wrap around peripheral nerves and form electrical insulation
what is 8th vestibulocochlear nerve schwannoma known as?
‘Acoustic neuroma’ at angle between pons and cerebellum
what are symptoms of acoustic neuroma?
Unilateral deafness
Benign lesion but removal technically difficult
how is a pituitary adenoma described?
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
Generally do not spread outside of CNS
what is a haemangioblastoma?
Tumour of blood vessels
Space occupying
May bleed
Most often in cerebellum
how are secondary tumours described?
Mostly carcinomas
Common
Histology = that of the primary tumour
