ATRX and diffuse leptomeningeal glioneuronal tumor: Another important finding of this study was the high number of ATRX alterations detected in this series, which not only expands the spectrum of tumor types showing a recurrent loss of ATRX expression but also highlights a valuable diagnostic marker in particular in comparison to glioneuronal tumors such as extraventricular neurocytoma, diffuse leptomeningeal glioneuronal tumor or the recently described group of glioneuronal tumors driven by different kinase-fusions [25, 28].