Usefulness of (11)C-Methionine PET in differential diagnosis of epileptogenic brain neoplasms.

Brain tumors are associated to more than 50% of patients with epilepsy, of which about 30% are drug-resistant. Epilepsy associated with brain tumors is multifactorial, but fundamentally depends on its location and histology. So, low-grade tumors are more epileptogenic than high-grade. In high-grade tumors and adult epilepsy is associated with increased frequency of neurological deficits. In lowgrade tumors and infant-juvenile age, epilepsy presents clinically isolated.1,2 We present two women of similar age (27 and 25 years, respectively) following focal seizure who underwent Magnetic Resonance Imaging (MRI) that revealed similar findings: hypointense on T1weighted and high signal on T2-weighted and FLAIR images with areas of diffusion restriction and without contrast enhancement (left frontal and parietal-temporal right, respectively). These features can be presented in different tumor types and in our case not allow the differential diagnosis between a low-grade glioma or ganglioneuronal tumor (Figs. 1 and 2). The Dysembryoplastic Neuroepithelial Tumor (DNET) was described by Daumas-Duport et al. in 1988 as a mixed ganglioneuronal low-grade lesion (WHO grade I) containing oligodendrocytes,