Diffuse astrocytoma

From Libre Pathology
Revision as of 10:16, 22 October 2015 by Jensflorian (talk | contribs) (update)
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:[1]

  • 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!

Radiology/Clinic

  • Mass effect.
  • Seizures.
  • Neurologic decifit.
  • Usually not contrast-enhanching, T2 bright.

Macroscopy

  • No clear demarcation from white matter
  • May contain larger cysts
  • No necrosis

Histology

Features: [2]

  • Cell density higher than normal brain.
  • Mild to moderate nuclear pleomorphism.
    • Monotony of atypical nuclei and irregular distribution indicates neoplasm.
    • "naked nuclei" without recognizeable processes.
    • No prominent nucleolus.
  • Cytoplasm highly variable (even within the same tumour).
    • In normal CNS the cytoplasm blends within the neuropil.
  • Mitoses absent or very rare.
  • Microcystic spaces of the background (none to extensive).
  • No necrosis, no vascular proliferations.
    • Except radiation necrosis.
  • Lymphocytic cuffing (mostly in gemistocytic type)
  • Abent to few rosenthal fibers.


IHC

  • GFAP+ve.
  • MAP2+ve (especially in cell processes).
  • Vimentin+ve (often perinuclear).
  • S-100+ve.
  • p53: Nuclear staining in 30% of the tumours (usually few cells).
  • 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


See also

  1. 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.
  2. Burger, P.C.; Scheithauer, B.W. (2007). Tumors of the Central Nervous System (Afip Atlas of Tumor Pathology) (4th ed.). Washington: American Registry of Pathology. pp. 34. ISBN 1933477016.