CNS Tumours - Pathoma

Cell Type	Children - 70% subtentorial	Adults - most supratentorial
Astrocytes	Pilocyticastrocytoma	Glioblastoma multiforme
Oligodendrocytes		Oligodendroglioma
Ependymal cells		Ependymoma
Meningothelial		Meningioma (esp females)
Neurons	Medulloblastoma - actually from neuroectoderm	<don't really form tumours - permanent tissue by this age>
Mixed (e.g. oligoastrocytoma)

Graded by their likely rate of growth
Grade 1-2 low grade, well differentiated, better outcome
Grade 3-4 high grade, undifferentiated/anaplastic, poor outcome - children better: 5y ca 25% survival
Low grade astrocytomas more in younger adults - 20-30
Anaplastic astrocytomas, olidodenrogliomas present in mid forties
Grades + example:
1. low - pilocytic astrocytoma
2. low + diffuse infiltration
3. high -
  - anaplastic astrocytoma
  - anaplastic ependymoma
  - anaplastic oligodendroglioma
  - anaplastic oligoastrocytoma
4. high + endothelial cell prolif ± tumour necrosis - glioblastoma multiforme
Astrocytomas most common subtype
Often difficult to tell where margin is
Even if benign, can be dangerous - e.g. in brainstem
Greater cellularity, pleomorphism than normal brain

Glioblastoma Multiforme (GBM)

Malignant
High grade
Most common glioma in adults
& most common malignant CNS tumour in adults
Average age @ Dx = 55
Gross
- Crosses corpus callosum often - "butterfly glioma"
- Quite vascular so may haemorrhage
- liquefactive necrosis
Microscopic
- Marked hypercellularity
- + hyperchromatism
- + pleomorphism
- Central tumour necrosis
- Endothelial cell proliferation
- Get living cells lining up around the necrosis
- - pseudo-palisading
- As derived from glial cells, intermediate filament = GFAP
Spreads throughout brain, maybe into CSF but metastasis rare

Benign tumour of arachnoid cells
Most common benign tumour of CNS
F>M
- Tumour suppresses oestrogen Rs
May present as seizures
- Focal pressure effect
- Won't invade cortex (well...)
Imaging shows round mass attached to dura
- Possible meningeal tail
Gross
Micro
- whorled nests, but can get lots of cell patterns
- may get psammoma bodies due to calcification of necrosed cells
- quite vascular

Malignant tumour from granular cells of cerebellum
- from neuroectodermal tissue
Usually kids
Small, round blue cells
- Homer-Wright rosettes
- - the blue cells wrap around pink neuritic processes
  - typically seen in drop mets
Poor prognosis
Rapid growth, spread via CSF
- spread to spinal cord: drop metastases
Near midline

Malignant ependymal cells
Usually in kids
- so normally subtentorial
- also, in kids, these tend to be in ventricular system
Grows out into 4th ventricle
- Block CSF outflow
- So get hydrocephaly
Cells grow around vessels:
- Perivascular pseudorosettes
Special type:
- myopapillary ependymoma
- arises in filum terminale in adolescents/adults
- papillae with myxoid core

Tumour arising from epithelial remnants of Rathke's pouch
- Should obliterate once ant pit rises up from pharynx to meet post pit
- Found in sella tursica
Presents
- Supratentorial mass in kid, young adult
- Optic chiasm compression
- - Bitemporal hemianopia
Imaging
- Often calcified - "from mouth, teeth are calcified too!"
Benign but recurs when resected

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