WHO grading system for diffuse astrocytomas
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At the time the article was created Frank Gaillard had no recorded disclosures.View Frank Gaillard's current disclosures
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The WHO grading system is the most widely used system for grading diffuse astrocytomas (c.2022) and is an adaptation of the now superseded St Anne-Mayo grading system (also known as the Daumas-Duport grading system).
Grade 1 is reserved for localized astrocytomas (see WHO classification of CNS tumors for a complete list) and as such diffuse astrocytomas range in grade from grade II to IV:
grade 2: low-grade infiltrative astrocytoma
cellular atypia only
grade 3: previously known as anaplastic astrocytoma
increased mitotic activity
grade 4: previously equivalent to glioblastoma, now depends on molecular characteristics
necrosis typically with perinecrotic palisading
Gliomatosis cerebri does not have its own grade but rather is a highly infiltrative version of a low grade or anaplastic tumor which involves at least three lobes 5. It does, however, confer a worse prognosis.
It is worth noting that there are other grading systems (see diffuse astrocytoma grading) and the pros and cons of each have been the subject of extensive debate.
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- 3. Louis DN, Ohgaki H, Wiestler OD et-al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol. 2007;114 (2): 97-109. Acta Neuropathol. (full text) - doi:10.1007/s00401-007-0243-4 - Free text at pubmed - Pubmed citation