OLIG2 and oligodendroglioma: Based on the current classification criteria, the essential features of DGONC include the methylation profile of DGONC, nuclear clusters exhibiting oligodendroglioma-like morphology, strong expression of OLIG2 and synaptophysin, and absence of widespread GFAP expression, with the caveat that morphological features can be used for approximation in the absence of methylation; monosomy 14 is listed as a desirable but nonessential feature [1].