L41 - Pathology of Intracranial Tumours Flashcards
List causes of presenting symptoms from intracranial tumours?
Focal destruction of brain tissue
Cerebral edema
Mass effect: Distortion of intracranial contents
Raised intracranial pressure: compress on vital structures, transtentorial herniation
Identify the most common sites of intracranial tumour development in adults and children.
Adults: above the tentorium in one or the other cerebral hemisphere (supratentorial)
Children: posterior fossa in midline: cerebellum / brainstem (infratentorial)
Classification of Intracranial tumours.
1) Primary tumours
a) Neuroectodermal/ neuroepithelial tumours
b) Tumours derived from other structures in the cranial cavity
2) Secondary/ metastatic tumours:
- Commonly from lung, breast, kidney and malignant melanoma
Location of occurrence and extent of involvement of astrocytomas?
- Occur mainly in:
i) Brainstem, cerebellum in posterior fossa (children)
ii) Cerebral hemispheres (young adults) in frontal and temporal lobe
Diffuse involvement:
i) Cerebellar ones: often cystic, contain proteinaceous fluid
ii) diffusely infiltrates surrounding tissue
2 approaches to grading of astrocytoma?
1) scale 1-4 (WHO classification) with increasing anaplasia
2) Low-grade (i.e. well-differentiated) or High-grade (i.e. anaplastic, highly malignant) based on features
Prognosis and treatment of astrocytoma?
Tumour may undergo malignant (anaplastic) change often after 5-10 years
Treatment:
- accessible to excision but often incomplete
- chemotherapy / radiotherapy
Define the histological features that relate to different grades of astrocytoma?
- Increased cellularity
- Nuclear pleomorphism / hyperchromasia = grade 2
- Mitosis = grade 3
- Vascular endothelial proliferation, areas of necrosis = grade 4
Explain the difference in biologic malignancy and histologic malignancy of brain tumours?
- Histologically ‘benign’/ well-differentiated neuroectodermal tumours
e. g. astrocytomas, oligodendrogliomas and ependymomas
are rarely encapsulated and behave biologically malignant and diffusely infiltrate the surrounding tissue
or may advance to become histologically malignant too
Describe the pattern of mstastasis of histologically malignant neuroectodermal tumours?
Rarely metastasize outside CNS
spread within the brain and spinal by direct infiltration through brain tissue and by spread through the CSF
How do most histologically malignant neuroectodermal tumours exert their effects?
1) destruction of normal tissue
2) mass effect
3) obstruction of CSF flow which results in hydrocephalus
Normal function of oligodendrocytes?
form myelin sheath along fiber tract
Location of occurence, prognosis of oligodendroglioma?
Usually occur in the cerebral hemispheres of adults,: more commonly in the frontal and temporal lobes, uncommon in the occipital lobes
Favorable prognosis if well-differentiated (patients may survive for several years)
Describe microscopic and macroscopic appearance of oligodendroglioma?
Macroscopically:
Purple-brown
Relatively well-circumscribed (less infiltrative)
Little necrosis
Microscopically:
Calcification within the tumour
Characteristic ‘box-like’ appearance of cells
Clear halo (= cytoplasm) round the uniform round nucleus
Well-marked cell border
Location of occurrence of Ependymomas?
Arise from ventricular lining (ependymal cells)
Many in brainstem (= vital site), cerebellum, 4th ventricle
Histological features of Ependymomas?
Histologically well-differentiated:
- regular round nuclei
- true rosettes with cuboidal tumour cells surrounding central lumen
- Perivascular pseudo-rosettes = cells arranged around blood vessels = characteristic pink fibrillary halo around vessels
Prognosis and treatment of ependymomas?
- slow growth rate and encapsulated»_space; cure by surgical resection
- Mostly located in brainstem & cerebellum»_space; inaccessible to surgical excision»_space; high morbidity, mortality
- Does not respond well to chemotherapy / radiotherapy
Describe how Glioblastoma multiforme develops?
anaplastic gliomas with ambiguous origin
- Primary: arise from undifferentiated glial cells
- Secondary: Develop in pre-existing astrocytomas by progressive loss of differentiation
Location of occurence, Histological features of Glioblastoma multiforme?
- arise in cerebral hemispheres + infiltrate surrounding brain
Histological:
- necrosis, haemorrhage, edema
- Central necrosis surrounded by degenerate tumour and pseudo-palisades**
- extensive nuclear, cytoplasmic pleomorphism, multinucleate cells, hyperchromasia
- Active angiogenesis with conspicuous capillary endothelial proliferation»_space; Glomeruloid body** (grade 4)
Age of onset, prognosis and treatment of Glioblastoma multiforme?
Majority occur in patients > age 40
No cure
Survive <1 year
How does Glioblastoma multiforme develop into ‘butterfly lesion’?
Infiltration follow white matter tracts (e.g. fornix, corpus callosum) to spread across hemisphere
> > infiltrate ventricular system and subarachnoid space
Location of occurrence, age of onset and mode of spread of Medulloblastoma?
Arise in the vermis (in midline of cerebellum in posterior fossa)
Common tumours of childhood
seeds readily throughout CSF
Histological features of medulloblastoma?
- Small cells with densely staining ovoid nuclei, little cytoplasm
- Mitoitic figures
- Hyperchromatic nucleus
- Homer Wright rosette formation:
Nuclei arranged in a circle
Fibrillary processes extend into centre
Classification of medulloblastoma?
Subtypes by genetics:
Sonic hedgehog-activated
+/-
WNT-activated
Age of onset, location of occurence of meningiomas?
- older age groups, particularly in women
Mostly attached to:
- Dura on the base of skull (parasagittal, falx cerebri, base of brain); or
- Inner side of calvarium (surrounds the brain)
