IDH1 and glioblastoma: One might argue in such a situation that additional sequence analysis would be recommended in the setting of a low‐grade tumor in a young adult patient in which the likelihood of IDH mutation is high, but not in the setting of an elderly patient with a glioblastoma that had no prior history or histological evidence of a lower grade precursor (ie, a clinically and histologically classic primary glioblastoma).