New IDH1 I113T mutation associated with BRAF V600E mutation: new driver of gliomagenesis?

Background: IDH mutations and BRAF mutations are classically mutually exclusive and usually associated with infiltrative or circumscribed gliomas and glioneuronal tumors respectively.

Case report: We report the case of a 26-year old man with intracranial hypertension revealing voluminous right frontal lesion. Surgical resection was performed and pathological examination found two distinct tumoral areas: a glioma-like area with calcification without mitosis; a second with pleomorphic glial cells with higher Mib index, high CD34 expression and endothelial proliferation. No necrosis was recorded. Molecular analyses revealed both IDH1 I113T and BRAF V600E mutations. Although this glioma was difficult to clarify, diagnosis of pleomorphic xanthoastrocytoma with anaplastic feature was suggested based on the association of some pathological feature (eosinophilic granular bodies, reticulin network and diffuse CD34 expression) and the BRAF V600E mutation.

Conclusion: We report a new IDH1 mutation associated with BRAF mutation in a very unusual glial tumor.