DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR - A BENIGN TUMORAL CAUSE OF PARTIAL EPILEPSY IN YOUNG-PEOPLE

Dysembryoplastic neuroepithelial tumor (DNT) is a newly recognized bra in lesion first reported in 1988 by Daumas-Duport et al. The authors d escribed five cases of DNT, that occured in young people and were char acterized by partial seizures. Seizures could become intractable and s econdary generalised. Usually, the interictal neurological examination was normal. In most cases, computed tomography showed a supratentoria l, ''pseudocystic'' low density appearance associated in some cases wi th calcific hyperdensity or focal contrast enhancement. Magnetic reson ance imaging demonstrated a predominantly intracortical lesion. Common features included low signal intensity on T1-weighted images and high signal on T2-weighted images. Temporal and frontal lobes were mainly involved. Dysembryoplastic origin explained the clinical and radiologi cal stability and the benign evolution of this tumor. Tumor resection was required only when epilepsy was intractable or when there was intr acranial hypertension. Earlier intervention can prevent the physical a nd psychosocial damage resulting from chronic seizures and can improve the prognosis for these young patient. Histologically, DNT have been incorporated amond the category of neuronal and mixed neuronoglial tum ors. Three patterns are described: a simple form with a unique glioneu ronal element, a complex form with specific glioneuronal element, nodu les being made of multiple variants looking like astrocytomas, oligode ndrogliomas or oligo-astrocytomas, foci of dysplastic cortical disorga nisation, and a non specific form. When specific glioneuronal composan t is absent (50% of cases), the identification of DNT has therapeutic and prognostic implications because aggressive therapy may be avoided, sparing these young patients the long term effects of radio- or chemo therapy