IDH1 and neoplasm: The presence of the IDH1-mutation in most low grade gliomas but relatively few primary glioblastomas and the predilection for the frontal lobe raises the possibility that the tumour progenitors susceptible to IDH1 mutation normally reside in this region or migrate there prior to tumourigenesis.[9] In contrast to the previously described study, one-third of the IDH1-R132H positive tumours in the present study demonstrated large areas of avid CE.