Presentation
Headache.
Patient Data
There is a soft tissue hypoattenuating mass involving the cortex in the right superior frontal gyrus. No vasogenic edema or significant mass effect.
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 remodeling / 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.
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.