Presentation
Seizure.
Patient Data
Left frontal intra-axial mass lesion that involves cortex as well as subcortical white matter. The mass lesion causes mild effacement of the frontal horn of the left lateral ventricle, however, there is no marked associated midline shift. There are patchy foci of faint enhancement within the mass lesion which correspond with areas of increased perfusion. No regions of restricted diffusion or suscepability blooming within the lesion.
On spectroscopy, the lesion demonstrates increased choline and decreased NAA with a myo-Ins peak.
No remote intra- or extra-axial mass lesions or acute collections. No acute infarcts.
Mucosal thickening is noted within the ethmoid air cells and maxillary sinuses, inflammatory.
Conclusion: Left frontal intra-axial mass lesion likely represents a glial tumor. Enhancement with increased perfusion suggest either an intermediate grade tumor or a low grade tumor with oligodendroglioma components.
Case Discussion
Oligodendrogliomas are tumors that commonly present as a round or oval sharply marginated mass involving the cortex or subcortical white matter. They usually are hypointense compared to gray matter on T1 and hyperintense compared to gray matter on T2-weighted MRI images. The attenuation or signal can be heterogeneous due to calcification, cystic degeneration and hemorrhage (not in this case).
Contrast enhancement is common, but is not a reliable indicator of tumor grade, with only 50% of oligodendrogliomas enhancing to a variable degree, and usually heterogeneously. Furthermore, elevated relative cerebral blood volume (rCBV) is commonly observed in association with the enhancing areas.
Note: This case predates the recent (2016) revision WHO classification of CNS tumors, and thus molecular markers (IDH mutation and 1p19q co-deletion) are not available. As such, this tumor would now be classified as an oligodendroglioma NOS.
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