Presentation
Seizure.
Patient Data
MRI brain revealed a rather defined (2 cm) intra-axial space-occupying lesion at the right temporooccipital cortical region. The lesion displays hypo-intense signal on T1WI and high signal on T2WI and T2/FLAIR with bubbly appearance and no appreciable post-contrast enhancement. No associated perilesional vasogenic edema. Mild mass effect is exerted manifested as effacement of the related cortical sulci. The left cerebral hemisphere is unremarkable.
Diffusion-weighted imaging: The lesion shows no appreciable diffusion restriction; with the minimum ADC value of the lesion = 1.3 x10 -3mm2/sec.
Spectroscopy: Choline/Cr ratio =0.74 Choline/NAA ratio=0.95 NAA/Cho ratio = 1.41 NAA/Cr ratio = 1.05 Lactate peaks
Case Discussion
In cystic cortical tumors involving the temporal lobe, the general differential diagnosis includes DNET, PXA, ganglioglioma. Imaging features, in this case, make DNET more likely.
Dysembryoplastic neuroepithelial tumors (DNET) are usually seen as cortical based tumors in young individuals. It is most often located in the temporal lobe. It appears as a cortical-based "bubbly" appearing mass in the right parietal lobe. The FLAIR image shows a characteristic ring-like hyperintense signal (bright rim sign). No perifocal edema and no contrast enhancement are present.