Dysembryoplastic Neuroepithelial Tumors Share with Pleomorphic Xanthoastrocytomas and Gangliogliomas BRAFV600E Mutation and Expression

Abstract

Pediatric cortical glioneuronal benign tumors mainly include gangliogliomas (GG) [differential diagnoses pilocytic astrocytomas (PA) and pleomorphic xanthoastrocytomas (PXA)] and dysembryoplastic neuroepithelial tumor (DNT). DNT include the specific form and the controversial non-specific form that lack the specific glioneuronal element. Our aims were to search for BRAF(V600E) mutation and CD34 expression in DNT, PXA, GG and PA to correlate BRAF(V600E) mutation with BRAF(V600E) expression and to evaluate their diagnostic and prognostic values. Ninety-six children were included. BRAF(V600E) mutation was studied by sequencing and immunohistochemistry; CD34 expression was analyzed by immunohistochemistry. BRAF(V600E) mutation was detected in PXA (60%), GG (38.7%), DNT (30%, including 3/11 specific and 3/9 non-specific forms) and PA (12.5%). BRAF(V600E) expression was recorded in PXA (60%), GG (45.2%) and DNT (30%). CD34 expression was recorded in PXA (60%), GG (58.1%), DNT (25%) and PA (12.5%). Neither CD34 expression nor BRAF(V600E) status was predictive of prognosis, except for PA tumors where CD34 expression was associated with a shorter overall survival. In conclusion, DNT shared with PXA and GG, BRAF(V600E) mutation and/or CD34 expression, which represent molecular markers for these tumors, and we recommend searching for CD34 expression and BRAF(V600E) mutation in all DNT, especially the non-specific forms.