CNS tumor
Glial tumors
Glioma - general

Author: Eman Abdelzaher, M.D., Ph.D. (see Authors page)

Revised: 24 August 2017, last major update March 2012

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Glioma [title] CNS [title]

Cite this page: Abdelzaher, E. Glioma - general. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cnstumorgliomageneral.html. Accessed November 19th, 2017.
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)
Classification
  • 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

Exceptions:
  • 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