Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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January 9, 2020
Dysembryoplastic Neuroepithelial Tumor (DNET)
- Background:
- DNET is an uncommon, slow-growing, benign glioneural tumor typically located in the supratentorial cortex.
- Young adults and children are most affected.
- The occipital lobe is an unusual location for a DNET; most are found within the temporal lobe and less often in the frontal lobe.
- Clinical Presentation:
- The presenting symptom is typically treatment-resistant complex partial epilepsy.
- Key Diagnostic Features:
- DNETs appear as wedge-shaped lesions that have varying signal intensity with a hyperintense ring sign on FLAIR, giving a characteristic “bubble” appearance.
- Visualized as a heterogeneous microcystic cortical lesion with minimal surrounding edema
- Contrast enhancement is not typically visualized.
- Minimal mass effect present
- Differential Diagnoses:
- Focal cortical dysplasia: noncystic with T2 hyperintensity; can display cortical thickening, blurring of the gray-white matter junction, and abnormal appearance of the sulci or gyri adjacent to the lesion
- Ganglioglioma: visualized as strongly enhancing mural nodule and lacks “bubble” appearance; calcification is common
- Pleomorphic xanthoastrocytoma: prominent enhancing nodule and presence of significant vasogenic edema with leptomeningeal enhancement/dural tail
- Neuroepithelial cysts: can have a similar appearance on T1 and T2 but lacks the defining hyperintense ring sign on FLAIR
- Multinodular and vacuolating neuronal tumors: demonstrate a “bubbly” appearance but are usually located in the juxtacortical white matter as opposed to the cortex or superficial gray matter
- Cystic encephalomalacia with surrounding gliosis: sequelae of prior hemorrhage, ischemia, or infarct
- Clustered Virchow-Robin spaces: isointense to CSF; can appear cystlike on axial imaging; may demonstrate a radiating linear appearance on coronal and sagittal views along the perivascular spaces
- Treatment:
- Surgical resection without the need for chemotherapy or radiation
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