myxoid glioneuronal tumor (MONDO_0858944, a Monarch Disease Ontology entry) can be described as follows. A central nervous system benign neoplasm that is characterized by a dinucleotide mutation at codon 385 of the PDGFR gene. It usually occurs in the septum pellucidum but has also been described in the corpus callosum and periventricular white matter of the lateral ventricle. It is composed of oligodendrocyte-like cells in a prominent myxoid stroma.