neuro onc notes & pilocytic and diffuse astrocytoma

TP53 mutations are hallmark of low grade astros, EGFr mutations are hallmark of primary GBM/high grade. if high grade has tp53 mutation, likely transformed from a low grade.

Pilocytic astrocytoma WHO grade I
-slow growing, cystic, children young adults, associated w/NF-1
-rosenthal fibers (intermediate filament of astros)
-site: optic nerve, thalamus, basal ganglia, cerebellum
Presentation
-seizures not usual presentation because not cortical
-headache common presentation, visual loss
Imaging
-well circumscribed, contrast enhancing
-cysts
Histopath - rare mitosis, hyperchromatic nuclei, glomeruloid vascular prolif, rosenthal fibers
eosin granular bodies - located in astro foot processes (PAS positive)
Proliferation - low
Prognostic factors - long survival
NF-1 associated tumors -less aggressive
Higher mitotic activity

Pilomyxoid astrocytoma (WHOII)- has mucoid matrix, typical w/o Rosenthal fibers or Eosin gran bodies
location: hypothalamic/chiasm most common
Prognosis - more aggressive than pilocytic

Pleomorphic xanthoastrocytoma (WHOII)- favorable prognosis, lipidized cells, GFAP, S-100 EGB +
develops in children/young adults, 2/3<18yrs, superficial location (cerebrum)
90% supratentorial,
Presentation: seizure! b/c cortical/superficial preference
Imaging - edema not pronounced b/c slow growth
Histo - intracellular lipid, granular bodies, GFAP+, reticulin fibers,
Prognosis -80%@5 & 70%@10 yrs

Diffuse Astrocytoma - WHOII
-peak incidence 30-40 yrs,
location - supratentorium, presents w/seizures, speech difficulty,
imaging -T1 hypointense, T2 hyperintense, enhancement is very uncommon, but tends to happen with transition to anaplastic astro (WHOIII)
histo- well differentiated, fibrillary, absent mitoses,
differential diagnosis
-fibrillary- nuc atypia w/o mitoses, microvasc prolif
-gemistocytic at >35% gemistocytes (stressed astrocytes),
-protoplasmic -rare, large eosinophilic cytoplasm, displaced nuclei, perivascular lymphocyte infiltrate, low mitotic index,

prognosis of diffuse astros ~6-8yrs w/surgery, high variation.
young age at diagnosis is favorable, gross total resection increases survival, patients who present with only seizures do better than focal neuro deficit.