In IDH-mutant_1p/19qret glioma, the presence of AB/FS mismatch was closely related to the presence of T2/FLAIR mismatch, suggesting the presence of a more fluid-like compartment (probably micro-cysts, which are observed extracellularly in astrocytomas and intracellularly in oligodendrogliomas) but further studies are needed to explain the factors contributing to our results. The gene discussed is IDH2; the disease is oligodendroglioma.