Dysembryoplastic neuroepithelial tumor (DNET)

1. Dysembryoplastic neuroepithelial tumor
(DNET)
Neurosurgery & Neuroradiology Conference
Oct 7, 2016
Tanat Tabtieang MD
Department of Radiology
Faculty of Medicine, Chulalongkorn University
King Chulalongkorn Memorial Hospital

2. T1 T2 T1 +C
DWI ADC SWI

3. T1 T2 T1 +C
DWI ADC SWI

4. T1 T2 T1 +C
DWI ADC SWI

5. T1 T2 T1 +C
DWI ADC SWI

6. T1 T2 T1 +C
DWI ADC SWI

7. T1 T2 T1 +C
DWI ADC SWI

8. T1 T2 T1 +C
DWI ADC SWI

9. T1 T2 T1 +C
DWI ADC SWI

10. T1 T2 T1 +C
DWI ADC SWI

11. T2 FLAIR
T1 T1 +C

12. T2 FLAIR
T1 T1 +C

13. T2 FLAIR
T1 T1 +C

14. T2 FLAIR
T1 T1 +C

15. T2 FLAIR
T1 T1 +C

16. T2 FLAIR
T1 T1 +C

17. T2 FLAIR
T1 T1 +C

18. Imaging findings
• Multiloculated cystic lesion involving left amygdala, left
hippocampal gyrus, with extension to left choroidal fissure, left
perimesencephalic cistern and temporal horn of lateral ventricle
• Multiple cystic lesion mainly in gray matter of left hippocampus,
left parahippocampal gyrus, left fusiform gyri, left inferior frontal
lobe, inferior part of left insular cortex, left caudate nucleus, left
globus pallidus, left putamen, left thalamus, hypothalamus, left
parietal cortex
• Showing slightly hyperSI to CSF on T1WI, isoSI to CSF on T2WI
and partially suppressed with high SI rim on FLAIR
• No restricted diffusion, paramagnetic substance/blood product
• No definite enhancement

19. Diagnosis
• Dysembryoplastic neuroepithelial tumor (DNET)

20. DNET
• Benign mixed glial-neuronal neoplasm (WHO grade I)
• Frequently associated with cortical dysplasia
• Young patients with longstanding partial complex seizure
• Frequently drug resistant
• Common age: children and young adult (2nd – 3rd decades)
• Rare malignant transformation
• No to very slow increased in size

21. DNET
• Sharply demarcated cystic/multicystic mass arising from
cortical or deep grey matter
• Cystic “bubbly” intracortical mass
• Minimal or no mass effect
• No surrounding edema
• Usually not enhanced
• Location: any region of supratentorial cortex
• Most common: temporal lobe (45-68%)
• Frontal lobe (~30%)

22. CT findings
• Cortical/subcortical
• Low density
• Calcification ~ 20-36%
• Usually non-enhancing
• Faint nodular or patchy
enhancement in 20%
• Higher incidence of recurrence

23. MRI findings
• T1WI
• Multilobular hypointense bubbly mass
• Cortex, may extend to subcortical white matter and (rarely) basal
ganglia
• T2WI
• Multilobular very hyperintense on T2
• FLAIR
• Mixed hypo-isointense SI
• No peritumoral edema
• DWI
• High diffusibility
• T1WI +C
• Usually not enhanced
• Focal punctate or ring enhancement in up to 30%

24. T1 T2 FLAIR
T2 T2 T1 +C

25. PET
• F-18 FDG PET: Glucose hypometabolism
• Lower 11C-methionine uptake than in ganglioglioma or
glioma

26. Cortical based tumors
• Usually present with complex seizures
DDx
• Oligodendroglioma
• Ganglioglioma
• Pleomorphic xanthoastrocytoma (PXA)
• DNET

27. Oligodendroglioma
• WHO grade II
• Well-differentiated, slowly
growing but diffusely infiltrating
cortical/subcortical tumor
• Young to middle aged patient
• Variant e.g. Oligoastrocytoma,
anaplastic oligodendroglioma
>> more aggressive
• Best diagnostic clue:
• partially calcification
subcortical/cortical mass in
middle aged adult
• Typically T2 heterogeneous,
hyperintense mass
• Typical heterogeneous
enhancement
NECT
T1 +C
FLAIR
T1

28. T1 T2
T1 +C

29. Ganglioglioma
• Most common tumor causing
temporal lobe epilepsy (TLE)
• Well differentiated, slowly
growing neuroepithelial tumor
composed of neoplastic ganglion
cells and neoplastic glial cells
• Best diagnostic clue
• Partially cystic with mural
nodule, enhancing, cortical
based mass in child/young
adult with TLE
• In younger pt (< 10 years), more
cystic and larger
T2
T1 +C

30. Pleomorphic xanthoastrocytoma
• Low-grade WHO grade II
astrocytoma variant
• Rare tumor of childhood and
adolescents with chronic epilepsy
• Most common site: temporal lobe
• Peripheral located hemispheric
mass
• The overlying dura may be
thickened and enhancing (unlike
ganglioglioma)
• Best diagnostic clue:
• Supratentorial cortical mass
with adjacent enhancing dural
tail
• Cyst and enhancing mural
nodule
T1 +C
T2 T1 +C