A high-grade glioma with amplification.

The molecular alterations underlying progression of low-grade glial/glioneuronal tumors remain to be elucidated. We present a case of a 56-year-old male with an enhancing left temporal lobe tumor. Histology revealed a high-grade glioma adjacent to a low-grade glioneuronal component with abundant Rosenthal fibers, focal eosinophilic granular bodies, and CD34-positive neurons. The tumor was negative for IDH1 (R132H), BRAF-V600E, and the fusion. Comparative genomic hybridization detected a large amplification (> 15 copies) of the () gene, a component of the MAPK pathway. Although activating mutations in the MAPK pathway occur frequently in gliomas and glioneuronal tumors, gene amplification has not been reported previously. This case indicates another potential mechanism for MAPK activation in glial tumors.