Glioblastoma NOS (bevacizumab pseudoresponse)

Case contributed by Dr Bruno Di Muzio


Patient received the standard treatment for a right temporal GBM.

Patient Data

Age: 70 years
Gender: Male

MRI Brain (Follow-up)

Comparison has been made with the previous scan.

T2 weighted scans showed an extension of the abnormal signal within the right temporal and occipital lobes, particularly into the parahippocampal gyrus and the white matter immediately surrounding the occipital horn.

The white matter extension now involves the right side of the splenium of the corpus callosum.

Postcontrast scans show medial extension of contrast enhancement to the level of the right occipital horn, which the contrast enhancing tissue encases.

Mass effect remains minimal. Spectroscopy in the enhancing areas shows only minimal increase in choline to creatine ratio (not illustrated above), but does show very high lactate peaks.

There is very slight increase in relative cerebral blood volume in the enhancing tissue.

Conclusion: The extension into the splenium of the corpus callosum and apparent slight increase in cerebral blood volume is more suggestive of recurrent tumor.

This patient had tumour progression when compared to the previous scan and a rescue treatment was proposed with bevacizumab. 


MRI Brain (after bevacizumab)

Right sided craniotomy and postsurgical change are again demonstrated.

The degree of contrast enhancement has markedly decreased attributable to Avastin therapy. Although the intensity and mass effect of associated tumor edema has also reduced, it now can be seen extending across the splenium of the corpus callosum and down into the occipitocervical temporal gyrus.

MRA's confirms treatment effects, elevation of lactate and lipids and reduction in the other metabolites.

Conclusion: Marked response: reduction in the intensity of contrast enhancement and T2 signal abnormality, but extension of tumor edema across the splenium is now evident.


MRI Brain (follow-up)

Right sided craniotomy noted.

Right cerebral hemisphere tumor, centered in the right tempo-occipital lobe has markedly progressed with new abnormal T2/FLAIR signal now extending into the corpus callosum (with new expansion), and into the left parietal lobe and mesial left temporal lobe and further extension and mass effect in the anterior temporal lobe and further extension inferiorly into the right cerebellum.

Mass effect is increased with further compression of the right lateral ventricle and slightly increased midline shift measuring 5 mm but no evidence of hydrocephalus or tonsillar herniation.

Portions of the tumor demonstrate diffusion restriction. Enhancing tissues surrounding the previous resection site has markedly increased in size with new right lateral ventricle subependymal enhancement now present.

CBV is not convincingly elevated and spectroscopy demonstrates elevated lactate and elevated choline on some voxels.

Conclusion: Compared to previous studies, findings would be in keeping with marked disease progression.

Annotated image

Bevacizumab effect over contrast-enhancement areas

Selected images from the study before and after bevacizumab introduction. The reduction in the contrast enhancement area is clear, which is a typical feature of this antiangiogenic drug.  

Case Discussion

This case illustrates a common follow-up for glioblastoma in which an antiangiogenic chemotherapy (bevacizumab) was introduced after tumor recurrence. Despite the marked contrast enhancement and edema reduction observed from the first exam to the second one, after the antiangiogenic therapy, the tumor showed a slight progression through the splenium of the corpus callosum. These features demonstrate what is known as pseudoresponse


Note: IDH mutation status is not provided in this case and according to the current (2016) WHO classification of CNS tumors, this tumor would, therefore, be designated as a glioblastoma NOS, even though it is almost certainly and IDH wildtype tumor. 

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Case information

rID: 38836
Published: 9th Aug 2015
Last edited: 16th Jul 2018
Tag: rmh
Inclusion in quiz mode: Included

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