Discussion Author: James G. Smirniotopoulos, M.D.
WHO Grade I
Cell of Origin: Histogenesis uncertain. Hypothesized to arise from external granular layer of the cortex.
Synonyms: DNET or DNT
Common Locations: Cortical, temporal lobe
Demographics: May be seen at any age; most common in children and young adults
Clinical Presentation: Partial complex seizures, especially beginning before age 20
Histology: Diagnosis based on presence of:
1) a specific glioneuronal element, consisting of oligodendrocytes in a mucinous matrix in which neurons appear to float
2) glial nodules associated with cortical dysplasia.
Special Stains: Neuronal markers (synaptophysin, neuronal specific enolase) and glial markers (GFAP, S-100)positive. Despite benign behavior, may have high MIB-1 labeling index
Progression: Usually stable, even over long periods.
Radiology: Nodular cortical lesion without edema or mass effect. May have megagyric or multicystic appearance.
Occasionally may enhance or contain calcifications. CT may show calvarial remodeling.
Comments: Surgically curable cause of seizures.
20-50% of DNET may show enhancement - suggestive features include cortical involvement, lack of edema, and minimal to no mass effect.
J Neuroradiol. 2001 Dec;28(4):230-40.
Dysembryoplastic neuroepithelial tumors: CT, MR findings and imaging follow-up: a study of 53 cases.
Stanescu Cosson R, Varlet P, Beuvon F, Daumas Duport C, Devaux B, Chassoux F, Fredy D, Meder JF.
PURPOSE: To evaluate CT and MRI features and long term imaging follow-up of a large series of dysembryoplastic neuroepithelial tumors (DNTS).
PATIENTS AND METHODS: We retrospectively analyzed CT (100%) and MR imaging (83%) findings of 53 patients with complex (n = 14), simple (n = 6) or non specific histological
forms (n = 33) of DNTS. All patients underwent epilepsy surgery for the treatment of drug resistant partial seizures. Preoperative radiological follow-up from two to 10 years (81%) and a post-operative follow-up from one to
13 years (92%) were available.
RESULTS: DNTs are intracortical tumors with no mass effect and no peritumoral edema. An associated deformity of the
overlying skull was observed in 44% of the 34 patients with a cortical lesion of the convexity. We found a contrast enhancement of the lesion in 21% of cases, a calcic hyperdensity in 36% of cases and a cystic part in 7.5% of cases. DNTs were hypodense (82%) on CT examinations and had a decreased signal on the T1 Weighted Images (95%) and a hypersignal in T2 Weighted Images (100%) on MR imaging. Eighty-one percent of patients had a mean preoperative radiological follow-up of four years and the tumor was stable in size in all cases; 92% of patients had a mean post-operative radiological follow-up of 4.5 years
and no recurrence was seen.
CONCLUSION: Three radiological features of DNTs are
helpful for the diagnosis: cortical location, absence of mass effect and no surrounding edema. Clinical, radiological and histopathological findings have to be
considered together in order to assess the diagnosis and to
differentiate DNTs, which are stable lesions from gliomas.
AJNR Am J Neuroradiol. 1996 Mar;17(3):419-30.
AJNR Am J Neuroradiol. 1997 Sep;18(8):1592.
Dysembryoplastic neuroepithelial tumors: MR and CT evaluation.
Ostertun B, Wolf HK, Campos MG, Matus C, Solymosi L, Elger CE, Schramm J, Schild HH.
PURPOSE: To evaluate dysembryoplastic neuroepithelial tumors (DNTs) on MR and CT studies and to compare DNT with other frequently encountered epileptogenic glioneuronal lesions. METHODS: We analyzed the MR images and CT scans of
16 patients who had complex partial epilepsy and DNT with respect to tumor location, size, CT density, MR signal intensity, mass effect, contrast enhancement, and heterogeneity, and compared these features with CT and
MR findings in 51 cases of ganglioglioma and 33 cases of glioneuronal malformation.
RESULTS: DNTs were located in the temporal lobe in 14 patients and in the frontal lobe in 2 patients. The cortex was involved in all cases and thesubcortical white matter in 10 cases. Fifty percent of the tumors had poorly
defined contours. On MR images, 14 DNTs had multiple cysts and 2 had single cysts. Contrast enhancement was observed in 6 DNTs, and mass effect was present in 9. CT scans disclosed moderately hypodense lesions in 7 patients and
markedly hypodense cystic lesions in 6 patients. Two DNTs were calcified. Tumor hemorrhage with perifocal edema was observed in 1 case. Contrary to previous reports, slow but definite tumor growth was present during a 13-year period in 2 of 6 patients in whom serial CT or MR studies were obtained. CONCLUSION: A multicystic appearance on MR images is a characteristic feature of DNT and corresponds to its myxoid matrix and multinodular architecture. This feature is rare in gangliogliomas and glioneuronal malformations, and, as such, may help differentiate DNTs from these disorders.
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