Difference between revisions of "Diffuse astrocytoma"

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#redirect [[Neuropathology_tumours#Infiltrative_astrocytomas]]
'''Diffuse astrocytoma''' (AKA: ''diffuse, low-grade astrocytoma'') is a infiltrating astrocytoma occurring in the CNS white matter.
 
* Most common grade II WHO glioma in adults (peaks between 30-40 years).
* 10-15% of all [[astrocytoma]]s.
* Usually shows progression to [[glioblastoma]] sooner or later.
 
Previously categorized as follows:{{Ref WHOCNS|25}}
*Diffuse astrocytoma ICD-O: 9400/3
**Fibrillary astrocytoma ICD-O: 9420/3 - most frequent
**Gemistocytic astrocytoma ICD-O:9411/3
**Protoplasmatic astrocytoma ICD-O:9410/3 - rare
Note: This subtyping is no longer in use!
 
==Histology==
*Cell density higher than normal brain.
*Mild to moderate nuclear pleomorphism.
**Monotony of atypical nuclei hints at neoplasm.
*Cytoplasm highly variable (even within the same tumour).
**In normal CNS the cytoplasm blends within the neuropil.
*Mitoses absent or very rare.
*Microcystic changes of the background (none to extensive).
*No necrosis, no vascular proliferations.
 
===IHC===
*[[GFAP]]+ve.
*[[MAP2]]+ve (especially in cell processes).
*Vimentin+ve (often perinuclear).
*S-100+ve.
*MIB-1: 0-5% (mean: 2%).
*[[IDH-1]] (R132H)+ve in 60-70%.
*[[ATRX]] loss in 70%.
 
===Molecular===
*Absence of LOH 1p/19q.
*Tp53 mutations in approx. 60% (80-90% in gemistocytic, 50% in fibrillary types).
*MGMT promotor methylated in approx. 50%.
 
==DDx==
*Reactive astrocytosis.
*Demyelinisation.
 
 
<gallery>
File:Astrocytoma whoII HE.jpg | Astrocytoma, fibrillary type (WC/jensflorian)
File:Neuropathology case II 02.jpg | Astrocytoma, protoplasmatic type (WC/jensflorian)
</gallery>
 
=See also=
*[[Astrocytoma]].
*[[Neuropathology_tumours#Infiltrative_astrocytomas]]
 
{{Reflist|2}}


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Neuropathology tumours]]
[[Category:WHO grade II tumours]]
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