Diffuse astrocytoma

From Libre Pathology
Revision as of 15:32, 21 October 2015 by Jensflorian (talk | contribs) (not complete)
Jump to navigation Jump to search

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 astrocytomas.
  • Usually shows progression to glioblastoma sooner or later.

Previously categorized as follows:The International Agency for Research on Cancer (Editors: Louis, D.N.; Ohgaki, H.; Wiestler, O.D.; Cavenee, W.K.) (2007). Pathology and Genetics of Tumours of Tumors of the Central Nervous System (IARC WHO Classification of Tumours) (4th ed.). Lyon: World Health Organization. pp. 25. doi:10.1007/s00401-007-0243-4. ISBN 978-9283224303.


  • 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.


See also