HistoPath - Neuro-oncology Flashcards
How are brain tumours classified (WHO)
Grade 1 - Extra-axial:
- Meningothelial cells – meningioma
- Schwann cells – schwannoma
Grade 2-4 Intra-axial (infiltrate the tissue of the brain):
- Astrocytes – astrocytoma
- Oligodendrocytes – oligodendroglioma
- Ependyma – ependymoma
- Neurons – neurocytoma
- Embryonal cells – medulloblastoma (Children)
How are brain tumours graded
via histological criteria (proliferative activity, cell differentiation, necrosis)
Grade I = benign, long-term survival
Grade II = cause death in >5 years (long survival)
Grade III = cause death <5 years (short survival)
Grade IV = cause death <1-year (short survival)
What are the risk factors for CNS tumours
Largely unknown
Radiation to head and neck → meningiomas, gliomas
Neurocarcinogens
Genetic predisposition (<5%):
- neurofibromatosis (AutDom)
- Tuberous sclerosis
- Brain tumour polyposis syndrome 1
- Gorlin syndrome
- Von Hippel Lindau
What is the inheritance of neurofibromatosis and what CNS tumours does it predispose to
Neurofibromatosis 1 (17q11) → neurofibroma, astrocytoma
Neurofibromatosis 2 (22q12) → schwannoma, meningioma
What are the signs and symptoms of a CNS tumour depending on where it is located
Intracranial: headache, vomiting, changed mental state
Supratentorial: focal neurological deficits, seizures, personality change
Subtentorial: cerebellar ataxia, long tract signs, cranial nerve palsies
What investigations should be done for CNS tumours
CT/PET-CT
MRI:
- MR-spectroscopy (metabolism)
- Perfusion MRI
- Functional MRI
What is the management for CNS tumours
- Surgery
- Craniotomy (debulking)
- Open biopsy (inoperable but approachable tumour)
- Stereotactic biopsy (if open biopsy is not indicated) - Radiotherapy (esp gliomas)
- Chemotherapy (esp gliomas) - temozolamide
What is the most common primary CNS tumour
Glial tumours (diffuse or circumscribed)
Circumscribed:
- Pilocytic astroctomas)
- SEGA
- Pleomorphic xanthoastrocytoma
Diffuse
- Diffuse astrocytoma
- Oligodendroma
Describe diffuse glial tumours
High grade, malignant progression
Supratentorial
Adults 20-40yo
IDH1/2 mutation present 30% of cases (+ve prognostic factor)
Astrocytoma (grade 2-4)
Oligodendrogliomas (Grades 2-3)
Describe circumscribed gliomas
Low grade, rarely malignant
Posterior fossa
Seen in children
BRAF mutationpresent in 50% of cases (MAPK pathway mutation)
Pilocytic astrocytoma (grade 1)
Ependymomas (usually)
Subependymal giant cell astrocytoma (Grade 1)
Pleomorphic xanthoastrocytoma (grade II)
Describe pilocytic astrocytomas (epidemiology, associations, imaging appearance, histopathology)
Most common child brain tumour
Seen in NF1 and with BRAF mutatoins
MRI: cerebellar; well circumscribed, cystic, enhancing
Histopathology:
- Piloid (hairy) cell
- Rosenthal fibres and granular bodies
- Slow growing with low mitotic activity
Describe diffuse astrocytomas (epidemiology, associations, imaging appearance, histopathology)
20-40yo
Cerebral hemispheres (adults), cerebellum (children)
IDH1/2 mutation in 80%
MRI: cerebral hemispheres, non-enhancing lesion, low choline:creatinine ratio
Histopathology: negligible/absent mitotic activity, vascular proliferation and necrosis absent
Will eventually become a glioblastoma
Describe glioblastomas (epidemiology, associations, imaging appearance, histopathology, cytology)
> 50yo
90% de novo with wildtype IDH, 10% progress from astrocytomas
MRI: heterogenous, enhancing post-contrast
Cytology: high cellularity, high mitotic activity, microvascular proliferation, necrosis
Histo: pathological blood vessels, blood vessel structural abnormalities, cellularity
Describe meningiomas (imaging appearance, histology)
Largely benign
MRI: extra-axial, isodense, contrast-enhancing
Histo: attaches to meninges, does not typically invade (displaces brain matter), globules seen
How are meningiomas graded
Based on histology (mitotic activity, cell morphology and brain invasion) per 10 HPF
Grade I (80%)= benign, recurrence <25% | <4 mitotic activity
Grade II (20%)= atypical, recurrence 25-50% | 4-20 mitotic activity
Grade III (1%)= malignant, recurrence 50-90% | >20 mitotic activity