CNS Tumours Flashcards
Know the major types of CNS tumours Know how to grade CNS tumours Know the major risk factors and genetic predisposition for CNS tumours Know the existing treatments and treatment resistance Understand the major imaging modalities
How common are CNS tumours?
CNS tumours are the 16th most common tumours, making up 2% of all malignancies
Which genetic conditions increase the risk of CNS tumours?
Neurofibromatosis types I and II
What is the relationship between mobile phone use and CNS tumours?
There is a very weak link due to the heat generated by the mobile phone in close proximity to the brain. The further away from the head the phone is used, the less the risk
Which age group are meningiomas most common in?
The elderly
Which age group are benign astrocytomas most common in?
Children
How common are CNS tumours in children?
They are the second most common malignancy after leukaemias and lymphomas
Name some symptoms of CNS tumours in children
Seizures, headache, weakness, clumsiness, difficulty walking, fever, staring, persistent projectile vomiting with no obvious cause, squint, neck tilt, precocious puberty, growth retardation, vision problems, and irritability
What are the red-flag symptoms for a headache caused by a space-occupying lesion, including a tumour?
Chronicity, no improvement with painkillers, worse at night and when lying down, pulsating nature, and a bifrontal, back of head, or throughout head location
Which imaging modality shows fluid and oedema in the brain?
MRI (FLAIR)
Why is MR spectroscopy useful in suspected CNS tumours?
It can identify biochemical markers for inflammation, normal brain, a slow-growing tumour, or an aggressive tumour. A marker for healthy brain is N-acetyl aspartase, found in neurons
Name the three main neurosurgical interventions for CNS tumours
Stereotactic biopsy, open biopsy, and craniotomy and debulking
Where do CNS tumours like to spread?
Along white matter tracts. CNS tumours rarely spread outside of the CNS
Define the grading of CNS tumours
Grade I - benign
Grade II - relatively benign, often slow growing, but will eventually develop into grade III. Typically curable with aggressive resection
Grade III - relatively malignant, almost as aggressive as grade IV, death typically within 5 years
Grade IV - malignant, death typically within a year
Name a genomic marker of glioma aggressiveness
ATRX loss with a TP53 mutation
Name a genomic marker of oligodendrogliomas which are less aggressive
1p/19q co-deletion
Name the four types of glioma
Astrocytomas, oligodendrogliomas, ependymomas, and mixed gliomas
What is the most common glial tumour?
Glioblastoma - representing 54% of glial tumours
Describe pilocytic astrocytomas
A benign, grade I tumour that commonly affects children
Describe diffuse astrocytomas
A grade II tumour that tends to invade the surrounding tissues but grow very slowly. Can be fibrillary, gemistocytic, or protoplasmic
Describe subependymal giant cell astrocytomas
A very rare grade II ventricular tumour associated with tuberous sclerosis. Can be cured with complete resection, but unfortunately is often difficult to fully resect
Describe the typical presentation of a pilocytic astrocytoma
Vomiting, behavioural changes, nausea, headache, and drowsiness
Which are of the brain do pilocytic astrocytomas usually occur in?
The cerebellum
Describe the appearance of a diffuse astrocytoma on MRI
A dark spot that does not take up contrast, usually with unclear margins
How do anaplastic astrocytomas usually present?
With a seizure, typically in a young adult
What is the prognosis with an anaplastic astrocytoma?
Below 40% survival at 5 years with complete resection, chemotherapy, and radiotherapy
How does glioblastoma multiforme usually present?
With seizures or focal neurological deficits - e.g. speech deficits if it involves Broca’s area - typically in an elderly patient
What does glioblastoma multiforme look like on MRI?
A large mass with contrast uptake at the edges but a central cystic core, as the centre becomes thrombosed due to irregular angiogenesis
Where do 50-60% of oligodendrogliomas occur?
Frontal lobes
Which tumour has a ‘fried egg’ appearance on histology?
Oligodendroglioma. Grade III (high grade) oligodendrogliomas also show increased cellularity and neoangiogenesis
Describe myxopapillary ependymomas
Grade I benign tumours which are slow-growing and typically affect the cauda equina of young adults
Describe the appearance of an anaplastic ependymoma in microscopy
Hypercellularity and rosettes
Why are medulloblastomas more common in children?
They are embryological tumours
What is the most common site for a medulloblastoma?
The cerebellum
What is the difference between adult and childhood medulloblastoma?
Childhood medulloblastoma is more common and usually occurs in the midline. Adult medulloblastoma is rare, but usually hemispheric
What does a sonic hedgehog mutation in medulloblastoma indicate?
More aggressive prognosis
Where do most meningiomas originate from?
Arachnoid cells
What are the main symptoms of meningioma?
Seizures and anosmia (from nerve compression)
What is the most common brain tumour?
Metastases
Which five cancers most commonly metastasise to the brain?
Melanoma, lung adenocarcinoma, breast carcinoma, renal cancer, and colon cancer
Why do melanomas like to metastasise to the brain?
They originate from the same germinal layer embryologically
Define craniopharyngioma
A benign tumour of the pituitary gland which develops from a remnant of the pharyngeal branches from pituitary migration
