CNS tumor
Diffuse astrocytic and oligodendroglial tumors
General

Author: Eman Abdelzaher, M.D., Ph.D.

Revised: 25 April 2018, last major update August 2017

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Astrocytic tumors CNS

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Cite this page: Abdelzaher, E. Diffuse astrocytic and oligodendroglial tumor - general. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cnstumorastrocytomageneral.html. Accessed June 18th, 2018.
Definition / general
  • See also WHO classification of CNS tumors
  • Recently, the 2016 CNS WHO classification grouped all diffuse gliomas (astrocytic or oligodendroglial) together based on an integrated phenotypic and genotypic classification; this approach sharply separates localized astrocytic neoplasms from diffuse gliomas (Acta Neuropathol 2016;131:803)
  • Diffuse gliomas include
    • WHO grade II and III astrocytic tumors
    • Grade II and III oligodendrogliomas
    • Grade II and III oligoastrocytomas
    • Grade IV glioblastomas
    • Diffuse gliomas of childhood
  • Based on the mutational status of isocitrate dehydrogenase 1 or 2 (IDH1 / IDH2), the recent WHO classification divides grade II diffuse astrocytomas and grade III anaplastic astrocytomas into categories
  • Similarly, glioblastomas are divided into categories:
    • IDH-wildtype (most cases)
    • IDH-mutant
    • NOS
  • Diagnosis of oligodendroglioma and anaplastic oligodendroglioma in adults requires the detection of both an IDH gene family mutation and 1p/19q codeletion
  • For diffuse astrocytic and oligodendroglial tumors, the modifier "not otherwise specified" (NOS) is reserved for those tumors in which full IDH evaluation and genetic study cannot be performed
  • Gliomatosis cerebri is now regarded as a special growth pattern found in several diffuse glioma subtypes rather than a distinct entity (Acta Neuropathol 2016;131:803)
    • It is characterized by an extensive involvement of the neuraxis
    • No distinct molecular alterations that distinguish gliomatosis cerebri from the well defined entities of diffuse glioma are recognized
  • WHO classification also attempts to separate some pediatric diffuse gliomas from their adult counterparts with the recognition of newly defined H3-K27M mutant diffuse midline glioma (Brain Pathol 2016;26:569)
  • Infiltrative nature usually hinders complete surgical resection
WHO 2016 classification
(Italicized items are provisional)
  • Diffuse astrocytic and oligodendroglial tumors
    • Diffuse astrocytoma, IDH-mutant
      • Gemistocytic astrocytoma, IDH-mutant
    • Diffuse astrocytoma, IDH-wildtype
    • Diffuse astrocytoma, NOS
    • Anaplastic astrocytoma, IDH-mutant
    • Anaplastic astrocytoma, IDH-wildtype
    • Anaplastic astrocytoma, NOS
    • Glioblastoma, IDH-wildtype
      • Giant cell glioblastoma
      • Gliosarcoma
      • Epithelioid glioblastoma
    • Glioblastoma, IDH-mutant
    • Glioblastoma, NOS
    • Diffuse midline glioma, H3-K27M mutant
    • Oligodendroglioma, IDH-mutant and 1p/19q codeleted
    • Oligodendroglioma, NOS
    • Anaplastic oligodendroglioma, IDH-mutant and 1p/19q codeleted
    • Anaplastic oligodendroglioma, NOS
    • Oligoastrocytoma, NOS
    • Anaplastic oligoastrocytoma, NOS
Diagrams / tables

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Algorithm for classification of diffuse gliomas

Gross images

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Diffuse glioma (diffuse astrocytoma)

Microscopic (histologic) description
  • Diffuse and infiltrative growth pattern is the hallmark of diffuse gliomas in general
  • Tumor cells tend to infiltrate along preexisting structures in grey and white matter (more common in oligodendrogliomas than infiltrating astrocytomas) forming what is known as secondary structures of Scherer which includes (Diagn Histopathol 2011;17:486)
    • Perineuronal satellitosis
    • Perivascular aggregates
    • Subventricular and subpial accumulation
    • Intrafascicular growth along white matter tracts
  • Infiltrative pattern could be accentuated by immunostains for mutant IDH1 protein which highlights infiltrating individual tumor cells and neurofilament protein which demonstrates trapped axons (Am J Clin Pathol 2012;138:177, Turk J Pathol 2008;24:194)
Microscopic (histologic) images

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Diffuse glioma

Positive stains
Board review question #1
What do diffuse astrocytic and oligodendroglial tumors have in common?

  1. Behave similar to localized astrocytic neoplasms
  2. BRAF alterations are a common finding
  3. Characterized by an infiltrative growth pattern
  4. Evaluation of IDH mutational status is irrelevant
  5. Primarily affect children
Board review answer #1
C. Characterized by an infiltrative growth pattern. An infiltrative growth pattern is the hallmark of diffuse gliomas in general.