Diffuse Glioneuronal Tumor With Oligodendroglioma-Like Features and Nuclear Clusters Relapse in a Seven-Year-Old Boy: An Unusual Case Exhibiting Near-Tetraploidy and Chromosome 14 Diploidy.

Diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) is a rare brain tumor of the central nervous system (CNS). Although only a few cases of DGONC have been reported following the initial description of the tumor, they have a distinct DNA methylation pattern and share a recurrent chromosomal finding of monosomy 14. We encountered a seven-year-old boy who presented with seizures and was found to have a left frontal and suprasellar mass. The tumor was grossly totally resected; histopathologic evaluation showed a cellular glioneuronal tumor with brisk mitotic activity. A near-tetraploid chromosome complement was detected, with associated diploidy of chromosome 14. Methylation pattern analysis revealed findings consistent with DGONC. Initially, we observed the patient without additional therapy. Due to the patient's non-metastatic relapse, resection of the relapse tumor consistent with DGONC and adjuvant radiotherapy were then initiated. The natural history and optimal post-surgical adjuvant therapy are unknown. This case adds to the limited number of DGONC cases previously reported, with a unique pattern of chromosomal abnormalities.