Overview Flashcards
Low-grade gliomas (LGGs) account for what % of all primary brain tumors?
∼10% of all primary brain tumors are LGGs.
Is there a racial predilection for LGG?
Yes. Whites are more commonly affected than blacks (2:1).
What are the histologic subtypes of LGGs?
Histologic subtypes of LGG (WHO 2016 update):
Grade I: pilocytic astrocytoma, subependymal giant cell tumor
Grade II: diffuse astrocytoma (fibrillary, protoplasmic, gemistocytic) including isocitrate dehydrogenase (IDH) mutant/wildtype; oligodendroglioma, IDH mutant/1p19q co-deleted; and oligoastrocytoma
What 4 pathologic features determine glioma grading?
Necrosis
Atypia
Mitotic figures
Endothelial proliferation
(Mnemonic: NAME or AMEN)
Which subtype of diffuse astrocytoma has the worst prognosis?
The gemistocytic subtype tends to de-differentiate and has the worst prognosis. Some prefer to treat it like a HGG.
Where anatomically does pilocytic astrocytoma most commonly present?
Most commonly presents in the PF (80% cerebellar, 20% supratentorial).
What pathologic feature is characteristic of pilocytic astrocytoma?
Rosenthal fibers are characteristic of pilocytic astrocytoma.
Where do grade II LGGs most commonly present?
Grade II LGGs most commonly present in the supratentorium.
What is the median age of Dx for pilocytic astrocytoma vs. other LGG?
The median age for pilocytic astrocytoma is 10–20 yrs and for grade II LGG is 30–40 yrs.
What genetic changes are important prognostic factors in LGG?
In LGG, LOH 1p19q and IDH mutations portend a better survival. p53 mutation indicates poorer survival and time to malignant transformation. IDH1 and IDH2 mutations are strongly associated with better prognosis.
What genetic change is prognostic in oligodendroglioma?
LOH 1p19q is prognostic in oligodendroglioma and is present in over 50% of cases. Associated with sup OS (MS 10 yrs in del 1p/19q vs. 3 yrs in intact) and PFS. (Jenkins RB et al., Cancer Res 2006)
What is the characteristic pathologic appearance of oligodendroglioma?
“Fried egg” appearance (round cells with nuclear halo) is characteristic of oligodendroglioma.
Where do most oligodendrogliomas occur in the brain?
Most oligodendrogliomas occur in the hemispheres (80%).
Anaplastic transformation from LGG to HGG occurs in what % of pts?
∼70%–80% of pts with LGG will undergo anaplastic transformation (based on EORTC 22845).
What chromosome is affected in NF-1, and with what type of gliomas is it associated?
NF-1 is a result of a mutation on the long arm of chromosome 17 (NF1/neurofibromin tumor suppressor gene) and is associated with optic/intracranial gliomas.
