Oligodendroglioma NOS

Case contributed by Assoc Prof Frank Gaillard


Adult patient presenting with a seizure.


CT brain

CT demonstrates an ill-defined region of positive mass effect with calcifications. 


MRI brain

MRI confirms the abnormality. which is high T2 and intermediate T1 in signal, with little contrast enhancement. MR perfusion demonstrates significantly increased CBV (area 'under' the purple curve) compared to the other side. 

Case Discussion

The patient went on to have a biopsy of the mass. 


Microscopic Description: 

Sections show a neoplasm comprised predominantly of small round cells demonstrating a minimal degree of pleomorphism and frequent perinuclear halos. No mitotic figures are evident. There is no endothelial proliferation and no necrosis is evident. Toluidine blue-stained plastic sections of the glutaraldehyde-fixed tissue show no additional findings.

Immunohistochemistry shows that scattered cells are positive for glial fibrillary acidic protein (GFAP). The lesion shows a uniform distribution of MIB-1 positive cells. No p53-positive cells were seen.

FINAL DIAGNOSIS:  This stereotactic brain biopsy shows histological features of a low-grade oligodendroglial tumor. Thus, the features are consistent with an oligodendroglioma.

Note: This case predates the recent (2016) revision WHO classification of CNS tumors, and thus molecular markers (IDH mutation and 1p19q co-deletion) are not available. As such, this tumor would now be classified as an oligodendroglioma NOS.

PlayAdd to Share

Case information

rID: 5309
Published: 2nd Jan 2009
Last edited: 13th Aug 2019
Inclusion in quiz mode: Included

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.