[Ependymal variant of dysembryoplastic neuro-epithelial tumor]

Dysembryoplastic neuro-epithelial tumors (DNET) are glioneuronal tumors with a common astrocytic or oligodendroglial differentiation. We report a case of DNET with an ependymal differentiation. A 13 years-old girl had refractory focal seizures for 3 years. Successive MRI showed a stable cortical lesion of the right temporal lobe with DNET characteristics. The lesion was resected. Histological examination revealed a pure ependymal differentiation characterized by perivascular pseudorosettes containing EMA immunoreactive cells. Mib1 positive cells were absent. In spite of histologic features of ependymoma, this tumor showed clinical, radiological and behaviour characteristics of DNET. We are not aware of any other case of DNET with ependymal differentiation in the literature. Our observation suggests that the glial component of DNET may show an ependymal differentiation.