CNS tumor
Oligodendroglial tumors
Oligodendroglioma - grade II

Topic Completed: 1 May 2012

Revised: 2 January 2019, last major update May 2012

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

PubMed Search: Oligodendroglioma [title] CNS

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Cite this page: Abdelzaher E. Oligodendroglioma - grade II. website. Accessed February 21st, 2019.
Definition / general
  • Diffusely infiltrating, well differentiated glioma of adults with frequent 1p- and 19q-
Clinical features
  • 5 - 15% of gliomas
  • Usually arise in cortex and white matter of cerebral hemisphere; > 50% of cases involve frontal lobe
  • 2/3 present with seizures
  • Mean age 42 years (grade II tumors); 2% occur in infancy / childhood
  • Slow growing tumors with median survival of 11.6 years and 10 year survival rate of 51%
  • Oligodendroglioma: WHO grade II
  • Oligoastrocytoma: WHO grade II
  • Grade II tumors may transform to grade III tumors, which have more cellularity, nuclear atypia, mitotic figures and pleomorphism
Radiology description
  • Well demarcated nonenhancing mass lesions, usually cortical and subcortical
  • Peritumoral edema is mild
  • Calcification is common
  • Hemorrhage and cystic change result in heterogeneous signal
Radiology images

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MRI and CT scan

CT scan

Case reports
  • Surgery; combination chemotherapy is helpful
Gross description
  • Well defined grayish pink masses
  • Appear more circumscribed than astrocytoma
  • May show mucoid change, areas of cystic degeneration, hemorrhage and calcification
Gross images

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Relatively sharp circumscription

Microscopic (histologic) description
  • Diffusely infiltrating glioma composed of monomorphic cells with uniform round vesicular nuclei, distinct small nucleoli and perinuclear halo (fried egg or honeycomb appearance)
  • Note: perinuclear halo is artifact due to fixation and is not present in frozen sections
  • Other features include: calcifications, mucoid and cystic degeneration, arborizing thin capillaries (chicken wire pattern)
  • Frequently involves cortex with secondary structures (perineuronal satellitosis, perivascular and subpial accumulation)
  • May contain minigemistocytes (cells with rounded nuclei and globoid eosinophilic GFAP+ cytoplasm) or gliofibrillary oligodendrocytes
  • Variable lobular growth pattern and nuclear palisading
  • Accepted in grade II tumors: rare mitoses, significant nuclear atypia and cellular nodules (with increased cellularity, atypia and mitotic activity)
Microscopic (histologic) images

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Oligodendroglioma - uniform cells with clear cytoplasm

High magnification


Metastatic tumor - fig 1: H&E; 2: GFAP+; 3A / B: primary tumor

Cytology description
  • Cells with monotonous nuclei, background granular matrix
Positive stains
Negative stains
Electron microscopy description
  • Abundant plasma membrane forms concentric layers mimicking myelin
  • Minigemistocytes show cytoplasmic whorls of intermediate filaments
Molecular / cytogenetics description
  • 1p-, 19q- are common (50 - 80% of tumors, Mod Pathol 2003;16:708 (FISH)); associated with favorable response to chemotherapy and longer survival
Differential diagnosis