Histopathology 14 - Neuro-oncology Flashcards
(48 cards)
Explain the difference between extra axial and intra-axial brain tumours
Extra-axial (coverings): (grade1)
tumours of bone, cranial soft tissue, meninges, nerves and metastatic deposits
Intra-axial (parenchyma): (grades 2-4)
Derived from normal cell populations of CNS (glia, neurons, vessels, connective tissue)
Derived from other cell types (metastases, lymphomas, germ cell tumours)
What does tumour grading tell us?
survival - NOT therapy response, disease spread or cell of origin
What is the most common form of primary brain tumour?
Glial tumours - gliobastoma multiforme
(Astrocytes, Oligodendrocytes, Ependymal cells, Schwann cells, Microglia, Satellite cells)
What are the 2 broad subtypes of glial tumours, and in which age groups are they typically seen?
Diffuse (adults) or circumscribed (children)
Diffuse vs circumscribed gliomas
diffuse gliomas
grades ≥II, adults, supratentorial, malignant progression
diffuse astrocytoma, GBM, oligodendroglioma
circumscribed gliomas
grades I-II, children, often posterior fossa, rare malignant transformation
pilocytic astrocytoma, pleomorphic xanthosastrocytoma, subpendymal giant cell astrocytoma, ependyoma
What grade are diffuse vs circumscribed glial tumours?
d: ≥2
c: 1 or 2
What mutation is associated with diffuse vs circumscribed gliomas?
Diffuse - IDH1/2 in 30% (positive prognostic factor - longer survival and better response to chemo and radiotherapy) + H3 (1%)
Circumscribed - MAPK pathway mutations (BRAF, NF1, FGFR1)
Describe the progression of all diffuse glial cell tumours
Cannot be removed surgically, so all progress to glioblastoma within 10 years
Which gene mutation is associated with diffuse glial cell tumour prediliction?
IDH gene
Epidemiology of diffuse astrocytoma
Patients 20-40yo
What would you see on MRI in diffuse astrocytma?
Cerebral hemispheres (adults), cerebellum (children)
MRI: T1 hypointense, T2 hyperintense, non-enhancing lesion
Low choline: creatinine ratio at MR-spectroscopy
describe the epidemiology of glioblastoma multiforme
>50y, increasing incidence with age
10% of cases secondary to astrocytoma (progression) - IDH mutation ( pos prognosis factor)
What would you see on MRI in GBM?
cerebral hemispheres
heterogenous, enhancing post-contrast
describe the histological features of glioblastoma multiforme
high cellularity, high mitotic activity, microvascular proliferation (neoangiogenesis), necrosis
What is the most common type of circumscribed glial tumour?
Pilocystic adenoma
Most common child brain tumour (20% CNS tumours <14yo)
Which brain tumour is an indolent CNS tumour of childhood?
Pilocystic astrocytoma
Mutation of which gene is associated with circumscribed glial tumours?
BRAF gene mutation
What would see on MRI in pilocystic astrocytoma?
MRI: cerebellar; well circumscribed, cystic, enhancing
What would you see on histology in pilocystic astrocytoma?
Piloid (hairy) cell
Rosenthal fibres and granular bodies
Slow growing with low mitotic activity
How can glioblastoma and diffuse astrocytoma be differentiated on CT?
Glioblastoma = enhancing
Diffuse astrocytoma = non-enhancing
Which mutation is most associated with pilocystic astrocytoma?
BRAF mutation in 70%
Describe the epidemiology of meningiomas
Rare in patients <40yo
increasing incidence with age
Which genetic syndrome is associated with meningioma?
Neurofibromatosis type 2
What tumour type typically takes part in microscopic brain invasion
meningiomas
Attaches to meninges but does not typically invade, just displaces brain matter
If they do invade, it is often a micro-invasion (as pictured)
