Fig. 1

Radiologic, histologic, and molecular features of a recurrent anaplastic glioneuronal tumor in a 71-year-old male. T1-weighted, post-contrast imaging shows a ring-enhancing mass adjacent to the right temporal resection cavity (a). Histologic patterns included compact fascicular regions including binucleated ganglion-like cells (b, inset), and lower cellularity regions with perivascular lymphocytic inflammation and abnormal ganglion cell body staining for neurofilament (c, inset). Still other regions had a nodular pattern with ganglion-like cells showing numerous vacuoles, but containing OLIG2 positive and NeuN negative cells (d-f). Next-generation sequencing revealed a small in-frame deletion in exon 2 of MAP2K1 resulting in p.Q56_V60del in both low-grade and high-grade tumor components (g). Both components also harbored focal homozygous deletion of the CDKN2A/B tumor suppressor genes on chromosome 9p21 (h). Full genome-wide copy number profiles are provided in additional file