H3F3A-G34R mutant high grade neuroepithelial neoplasms with glial and dysplastic ganglion cell components

a-c, pre-operative MR of case 1 T1-weighted pre- (a) and post- (b) gadolinium images showed a fronto-insular mass with hypointensity and heterogeneous enhancement. On FLAIR- (c) and T2-weighted images (d), the tumor displayed a solid component with slight hyperintensity and signs of surrounding edema. The mutation was confirmed by pyrosequencing (e). The upper part shows the mutation in tumor tissue as compared to the control sample, shown below. f-i, histopathology of case 1. Hematoxylin phloxin safranine stain revealed a tumor with both neuronal and glial components. Large multinucleated neurons (f), positive for chromogranin A (insert), and a major glial diffuse component (g), positive for GFAP (insert) were found. H3-G34R was positive in neoplastic neuronal cells (h, thin arrow) and in neoplastic glial cells (i), but negative in non-neoplastic neurons (h, thick arrow). j-n, histopathology of case 2 The tumor displayed abundant binucleated ganglionic cells (j) as well as glial tumor cells (k), both positive for H3-G34R (l). The dysplastic ganglion cells strongly expressed chromogranin (m) and showed nuclear accumulation of p53 (n