A very rare, low-grade midline brain neoplasm that affects the septum pellucidum. It is characterized by similar histological features to those found in dysembryoplastic neuroepithelial tumor, but does not display multinodularity. It usually manifests with symptoms related to increased intracranial pressure. Epilepsy has been reported in approximately one third of patients. PDGFRA gene mutations have been identified in the majority of patients. Alterations in FGFR1 and NF1 genes have also been reported. BRAF mutations which represent the most common molecular alteration found in cortical dysembryoplastic neuroepithelial tumor, were absent in this rare group of midline tumors. [from NCI]