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'''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]] | |||