CNS tumor
Glial tumors
Glioma - general

Topic Completed: 1 March 2012

Minor changes: 10 February 2020

Copyright: (c) 2002-2020,, Inc.

PubMed Search: Glioma [title] CNS [title]

Eman Abdelzaher, M.D., Ph.D.
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Cite this page: Abdelzaher E. Glioma - general. website. Accessed May 26th, 2020.
Definition / general
  • Most common CNS tumor
  • Includes astrocytoma, ependymoma, glioblastoma, oligodendroglioma and various subtypes / combinations
  • Diagnosis of "glioma" may be used for frozen section but is not a final diagnosis
  • Important to identify oligodendroglial component, due to effectiveness of chemotherapy for these gliomas
  • Presence of thrombosed vessels in tumors may predict postoperative systemic thromboses (J Neurosurg 1998;89:200)
  • The etiology of gliomas is not entirely understood, but a known risk factor is radiation therapy to the cranium, and gliomas in this setting usually arise 5-25 years after exposure
  • Benign: does not recur; applies to pilocytic astrocytomas, certain gangliogliomas and ependymomas; may still have poor prognosis due to location that makes it difficult to resect completely
  • Low grade: may recur as high grade and kill patient
  • Gliomatosis cerebri: diffuse and extensive involvement of CNS associated rarely with glioma; MRI and biopsy helpful for diagnosis
Microscopic (histologic) description
  • Biopsies of tumor epicenter have cellularity greater than surrounding brain
  • Biopsies of margin only are difficult to grade; often contain granular calcifications among hypercellular glia
  • Also microcysts and mitotic figures (depending on tumor grade)
  • May have uneven distribution of cellular density that obscures gray white junction or spawns secondary structures of Scherer (subpial and perineuronal neoplastic glia)
Positive stains

  • Oligodendroglioma cells have variable GFAP and are Leu7+ and S100+
  • Xanthoastrocytomas are reticulin+
Negative stains
Differential diagnosis
  • Gliosis: even distribution of cellular density, contracts instead of expanding near hypercellular glia; usually less pleomorphism, no nuclear hyperchromasia, no nuclear cluster formation, no nuclear molding, no mitotic figures, no calcifications
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