Diffuse astrocytoma NOS ("protoplasmic")

Case contributed by Dr Bruno Di Muzio



Patient Data

Age: 40 years
Gender: Male

CT Brain

There is a soft tissue hypoattenuating mass involving the cortex in the right superior frontal gyrus. No vasogenic edema or significant mass effect. 


MRI Brain


The superior frontal gyrus is expanded and FLAIR-hyperintense. The margins are quite well defined. No abnormal diffusion restriction, magnetic susceptibility or enhancement is appreciated. Spectroscopy suggests only mild choline elevation (non-specific), without significant NAA depletion or lactate/lipid peak (not shown). Cerebral blood volume is not elevated. Mild remodelling / scalloping of the overlying skull vault is noted.

No further mass is identified. Note is made of a prominent cisterna magna (a normal variant) and maxillary sinus mucosal thickening.

Conclusion: Findings most in keeping with a low-grade glioma in the right superior frontal gyrus.

Annotated image

Comparison between T2 and FLAIR showing tumor substantial T2 FLAIR suppression. 

Case Discussion

This case was histologically proven to be a protoplasmic astrocytoma, which is one of the variants of diffuse low grade astrocytomas

This tumor tends to occur in young adults with a reported predilection to frontal and temporal lobe. On imaging, they typically present as a cortical mass with a very high signal on T2 that characteristically suppress on FLAIR sequence (represent the areas with abundant microcystic change). 

Note: Until recently, protoplasmic astrocytomas were classified as a subtype low-grade astrocytoma, however, in the latest (2016) update to WHO classification of CNS tumors, protoplasmic astrocytomas no longer exists as a distinct entity, but rather are considered as a pattern of certain gliomas, requiring IDH +/- 1p19q status for classification. 

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 diffuse astrocytoma NOS.

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Case information

rID: 38388
Published: 28th Jul 2015
Last edited: 16th Jul 2018
Tag: rmh
Inclusion in quiz mode: Included

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