Presentation
Seizures and left foot drop.
Patient Data
Right high frontal subcortical space-occupying lesion. It elicits a low signal on T1 and a high signal on T2 WI with rather a low signal on FLAIR WI giving the characteristic T2/FLAIR mismatch. No diffusion restriction or post-contrast enhancement. Thin rim of surrounding edema signal. MRS showed mild elevation of the Choline/creatin ratio, preserved NAA peak, and absence of lipid/lactate. MRI Perfusion showed low rCBV. Diffusion tensor imaging and fiber tractography showed the 2-D cartography color-coded maps revealed near total loss of the related cranial ends of the right corticospinal tract. The 3 D tractography revealed evident focal attenuation of the related cranial margins of the right corticospinal tract in relation to the mentioned mass lesion. Preserved girth, color density and directionality of the rest of the right cortio-spinal tract as compared to the left side.
Conclusion: Findings are impressive of diffuse astrocytoma grade 2.
Pathology after excision revealed diffuse astrocytoma grade 2.
Immunostaining was negative for IDH 1 gene mutation.
Case Discussion
The case demonstrates typical features of astrocytoma grade 2 on MRI with a typical high T2 signal and a rather low signal on FLAIR WI giving the characteristic T2/FLAIR mismatch which is highly specific for IDH Mutation in non-enhancing Gliomas. No diffusion restriction or post-contrast enhancement. The lesion also shows typical features on MRS and MR perfusion with mildly elevated Choline/creatin ratio, preserved NAA peak, and absent lipid/lactate peak as well as low rCBV. The tractography revealed focal attenuation of the cranial ends of the ipsilateral corticospinal tract.
Pathology after excision revealed diffuse astrocytoma grade 2. IDH 1 mutation test was negative hence this represents (astrocytoma not otherwise specified). IDH 2 mutation test should be performed.
According to several papers, T2/FLAIR mismatch sign is not highly sensitive but highly specific for IDH Mutation in Non-Enhancing Gliomas. Providing this information, in addition to determining the alpha-ketoglutaric-peak on MR Spectroscopy is potentially useful for the Neurosurgeon, since there are studies claiming that IDH Mutant Gliomas benefit in some instances from supratotal resection (Wildtype Gliomas do not benefit from it).
Many thanks to Dr Adrian Zoican for his informative notes.
Unable to process the form. Check for errors and try again.