Dsyembryoplastic neuroepithelial tumour with discrete bilateral multifocality: further evidence for a germinal origin

We report the case of a middle aged woman who developed refractory complex partial seizures in her early twenties. She had a right coloboma and neurological examination was normal. Neuropsychological assessments revealed mild impairments of non-verbal memory, and visuospatial and constructional difficulties. Serial CT and MRI showed multiple nodular abnormalities in her mid-brain, diencephalon, subependymal region and both mesial temporal lobes. EEG recording revealed a right medial temporal focus. She underwent en bloc temporal lobectomy. The surgical pathology revealed mesial temporal dysembryoplastic neuroepithelial tumour (DNET) in association with extensive, contiguous neocortical dysplasia. The proliferation marker MIB-1 revealed up to 2% labelling in tumour areas resembling conventional oligodendroglioma. In the two years since surgery she has been seizure free and the remaining MR brain abnormalities have not changed. The very unusual centripetal MRI pattern of discrete multifocal lesions with the characteristic T1 and T2 features of DNET would support the dysembyroplastic germinal origin that was proposed by Daumas-Duport et al. (1988) in their original description of the lesion. The neuroradiological, neuropathological and clinical features of this case are compared with the two previous cases of multifocal DNET.