.svg?table=block&id=1e53f225-65dd-812b-b5d9-f2c2b0572495&spaceId=c36d71fb-a49e-422e-82b5-4697ad237ad9&expirationTimestamp=1748491200000&signature=3288hgO4iaPSDhBnZGPIFpZ1n2JTMMN-Pq7aHoeCaJ8)
Brain tumours are masses of cells in the brain that multiply in abnormal and uncontrollable manners. They may be primary (30%), deriving from the brain tissue itself, or secondary (metastatic spread from another site). Primary brain tumours may be benign (40%) or malignant.
🏘️ Epidemiology
Brain tumours tend to be more common in men, except for meningiomas which have a higher prevalence amongst women.
Let’s look at some of the most common benign and malignant brain tumours amongst certain populations:
- Paediatric tumours
- Benign paediatric primary brain tumour - pilocytic astrocytoma
- Malignant paediatric primary brain tumour - medulloblastoma
Other tumours common in children include: ependymomas, and craniopharyngiomas.
- Malignant tumours
- Benign primary brain tumour in adults - meningioma
- Malignant primary brain tumour in adults - glioblastoma multiforme
Other tumours common in adults include: haemangioblastomas, schawnnomas, oligodendriogliomas and pituitary adenomas.
😷 Presentation
The presence of any of the following may be a red flag for a brain tumour (primary or secondary):
- Headaches
- Signs/symptoms of raised intracranial pressure
- Reduced GCS
- Vomiting
- Headache on waking
- Headache worse on coughing/bending
- Confusion and deteriorating concentration
- Papilloedema
- Bulging fontanelles
- Cranial nerve lesion - the first one is usually CN6 (leading to strabismus).
- Signs of cerebral herniation
- New onset seizures - seen in 90% of low-grade gliomas, and around 30% of all brain tumours
- Focal neurological deficit
- Non-focal neurological deficit - changes to the CNS that do not correlate to a specific anatomical region in the brain.
- Cognitive behavioural and personality changes
🔢 Classification and types
Based on the cell type involved in the tumour, the following primary brain tumours can develop:
- Gliomas - from astrocytes or oligodendrocytes, including ependymomas.
- Meningiomas - arise from arachnoid cap cells of the arachnoid villi
- Embryonal ectodermal tumours - such as medulloblastoma and CNS neuroblastoma
- Pituitary tumours - such as craniopharyngioma
- Cranial nerve/paraspinal nerve tumours - such as vestibular schwannoma, neurofibromas, neuromas
- Pineal tumours
- Mesenchymal nonmeningeothelial tumours - divided into fibroblastic, vascular (such as haemangioblastoma), and skeletal.
- Choroid plexus tumours
- Neuronal and mixed neuronal-glial tumours
- Germ cell tumours
- Primary CNS lymphoma
Astrocytomas, are a form of gliomas, as they arise from astrocytes which are a type of glial cell.
Glial cells are non-neuronal cells that provide support and protection for neurons in the nervous system. They include several types, such as astrocytes, oligodendrocytes, microglia, and ependymal cells.
Astrocytes are star-shaped glial cells that provide structural support, regulate the chemical environment, supply nutrients, form the blood-brain barrier, and support synapse formation and function in the CNS.
Types of astrocytoma:
- Pilocytic astrocytoma (grade I astrocytoma)
- Insidious onset and slow progression of symptoms
- Vomiting
- Ataxia
- Failure to thrive in children
- MRI:
- Well-demarcated cystic lesion
- Bright contrast-enhancing solid nodule in the wall of the cyst
- Histopathology may show Rosenthal fibres (eosinophilic fibers with corkscrew appearance), bipolar cells and microcysts
- Diffuse astrocytoma (grade II astrocytoma)
- Anaplastic astrocytoma (grade III astrocytoma)
- Glioblastoma multiforme (GBM) (grade IV astrocytoma)
- MRI - shows the lesion with Garland-like (إكليل) enhancement, T1 hypo-intensity, T2 hyper-intensity
- Biopsy
- Dense, pleomorphic anaplastic cells (rapidly dividing + abnormally shaped) that form pseudopalisades (الحواجز) due to central necrosis or haemorrhage.
- Glial fibrillary acidic protein (GFAP) positive - an important diagnostic marker for astrocytomas; it is almost always positive in GBM!
- Shows microvascular proliferation
Pilocytic means that it looks like fibre when viewed under a microscope. This tumour is slow-growing (low-grade) and is the most common primary benign paediatric brain tumour (usually in people <20 years). It has good long-term survival, as it is completely curable with tumour resection.
It is associated with neurofibromatosis type I.
Clinical features:
Location: usually cerebellum, sometimes in the cerebral hemispheres (supratentorial).
Investigations:
❗️ An optic glioma is typically a pilocytic astrocytoma that arises from the glial cells in the optic pathway. Seen usually in those <10 years. It is also associated with NF1.
This is a slow-growing, infiltrative glial tumour and has the potential to progress to higher-grade tumours. It is incurable.
This is a high-grade infiltrative glial tumour with variable rates of growth. It is incurable.
This is a highly malignant brain tumour (grade IV astrocytoma) and is the most common malignant primary nervous system cancer. It usually affects people between 60-70 years. It is incurable, with a median survival of up to 15 months because it is highly invasive.
Clinical features: features of raised ICP, seizures, focal neurological deficit, etc [the typical manifestations of brain tumours]
Location: typically develops in the white matter of the cerebral hemispheres. Can cross the midline (butterfly glioma).
Investigations:
Management:
- Surgical resection - not curative
- Palliative radiochemotherapy [temozolomide, an alkylating chemotherapeutic agent]
- Adjuvant chemotherapy [temozolomide]
- Glucocorticoids
A medulloblastoma is a tumour that arises from the cerebellar vermis. It derives from primitive neuroectodermal tissue that did not differentiate into normal cells due to certain mutations or abnormalities.
The name “medulloblastoma” was given by Bailey and Cushing in 1925; they suggested that these tumours arise from a hypothesized CNS precursor cell called a medulloblast. This is not correct.
Epidemiology:
- This is the most common malignant primary tumour in children (25% of cases), and mostly occurs in the first decade of life.
Associated conditions:
- Turcot syndrome - rare, inherited disorder in which polyps form on the inside walls of the colon and rectum, and tumours form in the brain
- Li-Fraumeni syndrome - for the characteristics of Li-Fraumeni syndrome, think BLAST53: Breast cancer/Brain tumors, Leukemia/Lymphoma, Adrenocortical carcinoma, Sarcoma, and Tp53.
- Ataxia-telangiectasia
- Rubinstein-Taybi syndrome
- Gorlin syndrome
Features:
- The most common location is the cerebellum → cerebellar defects (ie broad-based gait)
- Most tumours arise within the cerebellar vermis (midline) → truncal ataxia; inability to maintain truncal stability and coordinate central trunk muscles. Most commonly manifests with an inability to sit upright and/or stand without support.
- Invasion or compression of the 4th ventricle → noncommunicating hydrocephalus → features of raised intracranial pressure (e.g., bulging anterior fontanelle, papilloedema, vomiting, headache)
- Drop metastases to the spinal cord are common → paraplegia
- Behavioural changes - very young children may not be able to express that, and it may instead be picked up by parents
Investigations:
- MRI - shows hypointense mass on T1, isointense mass on T2
- Biopsy - may show Homer-Wright rosettes, which are anaplastic small round blue cells that surround a central neuropil [yellow overlay]
Management:
The presence of drop metastases is a poor prognostic factor. 5-year survival rate is 60–80%.
- Tumour resection
- Chemotherapy +/- radiotherapy depending on age (no radiotherapy is <3 years)
Meningiomas are almost always benign, slow-growing tumours that arise from the arachnoid layer (specifically the arachnoid cap cells of the arachnoid granulations/ villi). Usually, these granulations are responsible for the absorption of CSF into the blood circulation, to maintain normal ICP in the brain.
Seeing as they are from the arachnoid-cap cells, they can occur anywhere in the CNS with a meningeal covering.
Most are grad I meningiomas (according to the WHO classification), and the rest are either grade II or III.
Epidemiology:
Meningiomas are the most common primary benign brain tumour (and most common primary tumour overall [both benign and malignant]) in adults. It accounts for almost 40% of all primary intracranial tumours. They are more common in females than males.
In children, it may be seen in those who have had radiation treatment for childhood cancers (5% incidence rate in that demographic).
Risk factors:
- Neurofibromatosis type II
- Genetic predisposition
Weak:
- There is an association with a history of breast or thyroid cancer
- Women exposed to fertility treatments or cyproterone acetate - increased incidence
- Transgender individuals exposed to high levels of oestrogen/progesterone - increased incidence
Features:
- Asymptomatic - as they are slow-growing and hence the body continuously adapts to the size of the growing tumour
The features of a meningioma vary widely based on the structures getting compressed. Based on the most common sites for a meningioma:
- Supratentorial convex (20%) → headaches, seizures and neurological deficits that are determined by the site of the tumour
- Sphenoid wings (20%) → visual deficits and face hyperesthesia
- Parasagittal angle (20%) → headache, seizures, lower extremity weakness
- Spinal (10%) → back pain and paraplegia
- Olfactory (10%) → anosmia and some visual defects
- Posterior cranial fossa (10%) → sensorineural hearing loss & facial nerve palsy, unsteady gait
- Falx cerebri (8%) → same as parasagittal angle meningiomas
- Foramen magnum (2%) →
- Early: specific pattern of sensory and motor deficits; unilateral upper extremity → ipsilateral lower extremity → contralateral lower extremity → contralateral upper extremity
- Late: spastic quadriparesis [weakness] and lower cranial nerve palsies leading to atrophy and fasciculations (ie tongue, trapezius, and sternocleidomastoid mm)
- Intraventricular (1%) → hydrocephalus leaading to headaches, papilloedema, and other signs of raised ICP
Investigations:
- 🥇 CT
- MRI is the imaging modality of choice. Likely shows a well-demarcated round tumour space occupying lesion.
- May show the dural tail sign: dura mater is typically thickened where it meets the meningioma and tapers off as it extends away, resulting in a tail-like appearance.
- Contrast enhancement would show a significant homogenous enhancement
- Biopsy - microscopy might show psammoma bodies (also seen in ovarian cancer - serous cystadenocarcinoma), whorls of meningothelial cells (onion peel arrangement), etc
Management:
- Surgical resection
- Radiotherapy
A primary CNS tumour that arises from oligodendrocytes, a type of glial cell in the central nervous system. May be benign or malignant, depending on the tumour grade. Ix: “fried-egg” on histology (round nuclei with clear cytoplasm).
A brain tumour that arises from the modified ependymal cells that line the walls of the cerebral ventricles and central canal of the spine.
Intracranial ependymomas (most commonly in the 4th ventricle) typically are more common among children;
Spinal ependymomas (from the intramedullary space) are more common among adults 15–40 years of age.
Ix: perivascular pseudorosettes
A rare, benign, primary CNS tumour of vascular origin that is almost always infratentorial and most commonly affects middle-aged adults. Ix: foam cells and high vascularity. Associated with von Hippel Lindau.
A suprasellar tumour that arises from a remnant of Rathke's pouch.
There are 2 histological variants: adamantinomatous craniopharyngiomas, which typically occur among children, and papillary craniopharyngiomas, which occur almost exclusively among adults. Craniopharyngiomas present with growth reatrdation, headache, bitemporal hemianopia, and endocrine abnormalities (e.g., hyperprolactinemia, hypopituitarism, diabetes insipidus).
A tumour that forms in or near the pineal gland and includes pineocytomas, pineoblastomas, and pineal germinomas. Can cause Parinaud syndrome (due to compression of the tectum), obstructive hydrocephalus (due to compression of the cerebral aqueduct), and precocious puberty (if it produces β-hCG).