Diffuse astrocytoma NOS ("protoplasmic")

Case contributed by Dr Bruno Di Muzio

Presentation

Headache.

Patient Data

Age: 40 years
Gender: Male
CT

CT Brain

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

MRI

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 tumour 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 tumour 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 tumours, 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 tumours, this tumour would, therefore, be designated as a diffuse astrocytoma NOS.

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Case information

rID: 38388
Case created: 17th Jul 2015
Last edited: 22nd Jun 2017
Tag: rmh
Inclusion in quiz mode: Included

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