Question 810
{"accessible":false,"alternatives":[{"id":4097,"text":"additional tests are required"},{"id":4098,"text":"astrocytoma grade 4 IDH mutant"},{"id":4099,"text":"astrocytoma grade 4 IDH wild-type"},{"id":4100,"text":"glioblastoma IDH mutant"},{"id":4101,"text":"glioblastoma IDH wild-type"}],"archived":false,"correctAlternativeId":4097,"explanation":"\u003cp\u003eThis is almost a trick question.\u003c/p\u003e\u003cp\u003eThe presence of necrosis in an astrocytic tumor is sufficient to make it a grade 4 tumor.\u0026nbsp;\u003c/p\u003e\u003cp\u003eThe issue is with IDH status. Although IDH1 R132H is the most common, but by no means the only IDH mutation, in this age group, there is a reasonable chance (5-10%) that they harbor a non-IDH1 R132H mutation and before the tumor can be adequately classified according to the 2021\u0026nbsp;\u003ca href=\"/articles/who-classification-of-cns-tumours-1\"\u003eWHO classification\u0026nbsp;of CNS tumors\u003c/a\u003e IDH needs to be sequenced to exclude an alternative IDH1 or IDH2 mutation.\u0026nbsp;\u003c/p\u003e\u003cp\u003eNote, if this tumor was shown to have a non R132H IDH mutation, it would be an astrocytoma grade 4, whereas if it was IDH-wildtype it would be a glioblastoma.\u0026nbsp;\u003c/p\u003e","id":810,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2768","nextQuestionPath":"/articles/glioblastoma-idh-wildtype/questions/715","relatedArticles":[{"id":39154,"title":"Isocitrate dehydrogenase (IDH)","link":"/articles/isocitrate-dehydrogenase-idh-1?lang=us"}],"alsoUsedIn":[],"stem":"\u003cp\u003eA 40-year-old male, with no prior history of a brain tumor, undergoes resection of a heterogeneous left frontal lobe tumor. Histology demonstrates an astrocytic tumor with necrosis and microvascular proliferation. Immunohistochemistry confirms astrocytic differentiation and is negative for IDH1 R132H mutations. How should this tumor be classified?\u003c/p\u003e","menuLinks":[{"text":"Report problem with question","url":"https://docs.google.com/forms/d/e/1FAIpQLSfO3soWYhOjJ7yErSysyCe5V4A1CqW7WK3rDA7MtAkecMGqNw/viewform?entry.1624461248\u0026entry.553583435=https://radiopaedia.org/questions/810"}],"attemptsPercentages":[{"alternativeId":"4099","percentage":17},{"alternativeId":"4101","percentage":36},{"alternativeId":"4100","percentage":11},{"alternativeId":"4098","percentage":7},{"alternativeId":"4097","percentage":28}],"promptToLogin":false,"questionManager":false,"articleId":"glioblastoma-idh-wildtype"}