High frequency of IDH-1 mutation links glioneuronal tumors with neuropil-like islands to diffuse astrocytomas

Excerpt

The glioneuronal tumor with neuropil-like islands (GTNI) is an uncommon histopathological entity composed of diffuse astrocytic or oligoastrocytic elements interspersed with sharply delimited, micronodular loci of neuronal differentiation. Despite its initial description over 10 years ago [10], the lineage classification of GTNI remains speculative. The clinical features of GTNI, its infiltrative growth characteristics, typically dominating astroglial components, and frequent p53 expression, are all consistent with a fundamental linkage to the diffuse astrocytic tumor group. Supporting this notion are reports documenting, by comparative genomic hybridization, an astrocytoma-like profile of 7q21.1-qter gain and 9p21-pter loss in one case [8] and the absence of oligodendroglioma-associated 1p/19q deletions in a series assessed by polymerase chain reaction-based loss of heterozygosity analysis [3]. …