Brain Tumors Flashcards
What are the most common brain tumors?
Primary CNS tumours are the most common paediatric solid tumours, accounting for 23% of malignancy in children under 15yo
Over 60% of paediatric brain tumours are infra-tentorial and often low grade.
Low grade astrocytoma (30%) High grade astrocytoma (10%) Medulloblastoma (20%) Ependymoma (8%) Brain stem glioma (6%) Germ cell (7%) Craniopharyngioma (6%) Oligodendroglioma (5%) Choriod plexus tumours 3% Other...
What is the leading cause of brain tumor death in children?
Brain stem tumours
- 80% is diffuse intrinsic pontine glioma
- compress nuclei / tracts in the pons causing cerebellar symptoms, long tract impairment resulting in weakness or sensory loss and paresis of CN VI, VII
Treatment
- palliative RT
What’s an astrocyte and what’s an astrocytoma?
Astrocyte is an star-shaped glial cell in the brain / spinal cord
- most abundant glial cells
- involved in physical structuring of brain including gliosis
- provide neutrons with nutrients (contains glycogen and capable of gluconeogenesis)
- takes up / release transmitters (glutamate, ATP, GABA)
Astrocytoma
- Glioma arising from the astrocyte
- 40% of all childhood brain tumours
- Occurs throughout CNS before astrocytes are everywhere!
- Makes up majority of supratentorial tumors
What types of astrocytomas are there?
Low grade astrocytomas include
1) Pilocytic astrocytoma
- classically found in the cerebellum
- on imaging: contrast-enhancing nodule within wall of cystic mass
- best prognosis with little metastatic potential
- a/w neurofibromatasis
2) Fibrillary
- seizures, headaches and hemiparesis are common px features
- found w/in the cerebral hemisphere
- infiltrating with malignant potential
3) Pleomorphic xanthoastrocytomas
- most arise from the temporal lobe causing temporal lobe seizures
- solid enhancing nodule, peripheral in location with leptomeningeal involvement
High grade
- anaplastic astrocytoma
- glioblastoma multiforme (GBM): most aggressive form of astrocytoma)
What is an oligodendroglioma?
Glioma arising from an oligodendrocyte
- usually found w/in cerebral cortex
- uncommon
- infiltrative
- has microcalcification
Treatment similar to fibrillary astrocytoma
What’s an ependymoma?
Glioma arising from ependymal lining of ventricular system
- 70% found in posterior fossa
- 10% of childhood brain tumours
- 10% risk of leptomeningeal spread through CSF
Features: - Usually well-circumscribed tumor with gadolinium-enhancement \+/- cystic components - Non-invasive - Poorer prognosis if in posterior fossa - no role for chemotherapy - 50% 5year survival
What’s a medulloblastoma and how do you treat it?
A Primitive neuroectodermal tumour (PNET)
- most common brain tumour to metastasise extra-neuronally
- little less than 30% will have spinal metastasis at presentation
- posterior fossa tumor by definition, majority arising in cerebellar vermis or cerebellar hemisphere in older patients
Epidemiology
- 3-8y
- M > F
Clinical features
- Raised ICP
- Ataxia
- Hydrocephalus in > 80% patients secondary to 4th ventricular obstruction
- A/w Gorlin syndrome and Turcot syndrome
Imaging
- solid, homogenous, contrast-enhancing on CT / MRI
Cytogenetic
- most common: 17p deletions
Management
- Surgery: corner stone of treatment
- Total CNS irradiation: avoid until > 4y
- Chemotherapy if higher than average risk of relapse such as incomplete surgical resection or intraspinal mets
Prognosis
- 5 year survival 50%
Where would you normally find a germ cell tumour?
Midline structures like the pineal or supra-stellar regions
- peak incidence 10-12y
AFP (non-germinomatous germ cell tumor) or BHCG (germinoma)
- useful in establishing diagnosis and monitoring response
Treatment
- Surgery +/- radiation +/- chemo
What are some syndromes that increases risk of brain tumors?
NF-1 - optic glioma - low grade astrocytoma NF-2 - acoustic neuroma - meningioma TS - ependymomas - glial tumors
What are side effects of cranio-spinal radiation?
Oncogenesis
- 5-10% secondary tumours
- 1/3 meningioma, 1/3 low grade glioma, 1/3 high grade glioma
Neuroendocrine
- Pituitary failure > 24 gray
- usually seen in 1 year
- GH > FSH/LH > TSH > ACTH
Intellect (reduced IQ / memory)
- increased risk with younger age
- first apparent at 12-24 months
Reduced growth
- Decreased GH
- Spinal irrad: epiphyseal groth arrest —> long legged / armed but short back
What are midline brain tumors?
Craniopharyniogoma
Optic chiasm glioma
Pineal tumors
Where does craniopharyngioma arise from?
From remnants of the Rathke’s pouch
- grows slowly from birth
- confined to sella turcica
- causes hypopituitarism i.e growth failure, low TFT +/- addisonian crises, DI, delayed puberty
If invades through, will compress on
1) optic chiasm
- bitemporal hemianopia / blindness
2) hypothalamus
- temperature irregulation / appetite changes
3) third ventricle
- hydrocephalus, raised ICP
Imaging
- cysts and calcification on MRI are characteristic
Treatment
- surgical resection
- RTx if incomplete removal
- no role for chemo
What are optic nerve gliomas?
Primarily low grade astrocytomas
- 25% assoc w NF
Can cause diencephalic syndrome if invades hypothalamus
- anorexia, wasting
- hyperalertness, euphoria
- coarse horizontal nystagmus
What causes gelastic seizures?
Hypothalamic harmartoma
- benign glial tissue on / near hypothalamus
Or other tumour invading the hypothalamus
Where is the pineal gland and what does tumors located there cause?
The pineal gland is found in the posterior part of 3rd ventricle
Causes:
- obstruction of CSF
- Parinaud syndrome: pressure on the quadrigeminal palate, resulting in paralysis on conjugate upward gaze and dilated fixed pupil
(Sound like paranoid and looks like it - image eyes wide open, looking downwards, fixed pupil)
Culprits
- germ cell tumours
- pinealomas
- mature teratomas
