PANARAB’12
NR28
IMAGING OF DYSEMBRYOPLASTIC
NEUROEPITHELIAL TUMORS. A STUDY
OF 6 CASES
Amina EL KHAMLICHI*, Meriem FIKRI*, Yasser ARKHA**, Najoua ECHCHERIF EL KETTANI*, My Rachid EL HASSANI*, Abdeslam EL
KHAMLICHI**, Mohamed JIDDANE*
*
Department of Neuroradiology
**
Department of Neurosurgery
Hôpital des Spécialités, CHU Ibn Sina, Rabat, Morocco
Introduction
• Dysembryoplastic Neuroepithelial Tumors (DNTs) include a large
morphological spectrum of tumors which histologically
resemble gliomas but are carcinologically perfectly stable
lesions. These tumors are seen in young patients with
intractable partial epilepsy.
• The purpose of this study is to evaluate CT and MRI features of
dysembryoplastic neuroepithelial tumors .
Materials and methods
• Our study concerns 6 cases of dysembryoplastic neuroepithelial
tumors histopathologically confirmed and diagnosed in patients
who underwent corticectomies between 1998 and 2011.
Table. Patient’s characteristics
Characteristics
No. of patients
(n = 6)
(%)
4
2
67 %
33 %
16 ± 15
6 – 26
2
4
33 %
67 %
5
0
1
83 %
0%
17 %
 Sex:
Male
Female
 Age:
Mean (yr)
Range (yr)
Adults (> 16 yr)
Children (< 16 yr)
 Histological forms :
Complex form
Simple form
No specific form
Materials and methods
• Clinical symptoms :
o Grand mal epilepsy (n = 2)
o Pharmacoresistant partial seizures (n = 3)
o Absence seizure (n = 1)
o Symptoms beginning :
* before age of 20 years : n = 4
* after age of 20 years : n = 2
o Symptoms of raised intracranial pressure (n = 1)
o Neurological deficit (n = 0)
Materials and methods
• All patients underwent brain MRI and CT.
• CT examination included axial and coronal sections before and
after contrast administration.
• MRI examination included T1 and T2 axial, sagittal and coronal
sections both pre- and postcontrast. FLAIR were also utilised.
Materials and methods
• Studied parameters :
 Location and topography
 Signal on T1, T2
 Contrast enhancement
 Calcifications and cystic component
 Size
 Limits
 Mass effect
 Peritumoral edema
Results
• In all cases  a single focal supratentorial lesion on CT and MRI
examinations
• Location : * Temporal lobes (67%) : right (n = 3) and left (n = 1)
* Right posterior parietal lobe (n = 1)
* Left frontotemporal lobe (n = 1)
Case 5
Case 6
Case 4
Case 3
Results
• CT scan : * Hypodense lesion (n = 6)
* ± Calcifications (n = 3)
* Non-enhancing tumor or faint enhancement of solid
portion.
Case 2
Case 1
Case 4
Results
• MRI : * Hypointense on T1-WI (n=6)
* Hyperintense on T2-WI and Flair images (n=6)
Case 2
Case 6
Results
• Contrast enhancement : * Ring shaped (n = 3)
* Nodular pattern (n = 2)
* No enhancement (n = 1)
Case 4
Case 5
Case 6
Results
• Lesion pattern : * Pseudocystic, multilobulated (n=5)
Case 6
Case 5
Case 4
Case 3
Results
• Mass effect : Minimal (n = 2), absent (n = 4)
• Peritumoral edema: Minimal (n = 1), absent (n = 5)
Case 2
Case 3
Case 4
Discussion
•
0.4 – 1.3 % of all brain tumors
Histopathology :
 Specific glioneuronal element : columnar structure made up of
bundles of axons lined by small tumoral oligodendrocytes.
 3 histological forms :
* simple : a unique specific glioneuronal element
* complexe : - a specific glioneuronal element
- a multinodular architecture
- foci of cortical dysplasia
* non specific : no specific glioneuronal element or
multinodular architecture
Discussion
Imaging
Three radiological features of DNT, not sensitive and not specific, are
helpful for the diagnosis :
• cortical topography
• no « digit like » peritumoral edema
• no mass effect
CT scan:
o Well-circumscribed hypodense lesion, which usually appears as non
enhancing mass
± Focal enhancement in 21 % of cases
± Calcifications in 36 % of cases
± Pseudocystic aspect in 50 % of cases
± « Scalloping »
o Brain CT was reported as normal in 10 % of cases (isodense small
lesion)
Discussion
MRI +++:
o T2 Weighted Images +++
o Tumor topography : cortex and/or subcortical white matter
involvement
o Hypersignal on T2 WI: 100 %
o Polymorphic aspect : « nodular » (77%) or « megagyri »
configuration (23%)
o Tumor size : 8 – 60 mm
o Microcystic pattern is common : « soap bubbles »
appearance
o True cyst is rare (7%) [size less to 1 cm]
Discussion
Imaging features according to the histologically forms :
 Simple form  pseudo-cystic, well delineated, homogenous
appearance with no calcifications or any
enhancement after contrast examination
 Complexe form  ring-like contrast enhancement,
calcifications
 Non specific form  nodular enhancement, « megagyri »
pattern, calcifications
Discussion
Positive diagnosis :
The diagnosis of DNT must be considered when the following
criteria are associated :
o MRI : intracortical lesion with no mass effect and no
peritumoral edema
o Histological feature resemble gliomas but without
lymphocytic infiltrates
o Partial seizures with or without secondary generalization
o Symptoms beginning before 20 years of age
o No neurological deficit or stable congenital deficit
Differential diagnosis :
* Ganglioglioma
* Low grade oligodendroglioma
Discussion
Follow-up :
* DNTs are carcinologically stable lesions
* Absence of recurrences after total resection
In our study, the mean follow-up was 21 months.
One patient developed tumor recurrence appeared
2 years after incomplete primary resection
Conclusion
• DNTs is a recently defined category of tumors in young
patients. These tumors histologically resemble gliomas but
behave as stable lesions. MR imaging allows a better
knowledge of their characteristic imaging features.
• Three radiological features of DNT are helpful for the
diagnosis: cortical location, absence of mass effect and no
peritumoral edema.
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