Presentation
Treatment resistant focal epilepsy. EEG shows left temporo-parieto-occipital focus. MRI to rule out structural cause.
Patient Data
High T2 weighted signal intensity lesion within the left parietal region which only partly suppresses on the fluid attenuated sequences. The bright rim sign is noted on FLAIR images. There is no contrast enhancement or abnormal restriction of diffusion.
The lesion is located peripherally, and although the majority of it is in a subcortical position it does involve the overlying cortex. There is some minor mass effect as evidenced by adjacent sulcal effacement.
No other epileptogenic foci are present
Case Discussion
Typical story of longstanding, treatment-resistant seizures.
The patient went on to have a biopsy which confirmed the diagnosis of a dysembryoplastic neuroepithelial tumor (DNET).
Although the bright rim sign on FLAIR images is useful, in larger tumors it is identical to T2-FLAIR mismatch seen in astrocytoma IDH-mutant.
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