Multifocal rosette-forming glioneuronal tumor-like low-grade glioneuronal tumor with dysembryoplastic neuroepithelial tumor features associated with drug-resistant epilepsy: a case report and literature review.

Rosette-forming glioneuronal tumors (RGNTs) are rare, World Health Organization grade 1 tumors that typically arise around the fourth ventricle. However, cerebral hemisphere RGNTs have recently been reported, with some exhibiting clinical features resembling low-grade epilepsy-associated tumor (LEAT). We report a case of multifocal RGNT in a patient with drug-refractory epilepsy. A 14-year-old woman was incidentally found to have multifocal brain tumor involving the left temporal lobe and bilateral thalamus, she developed drug-resistant epilepsy ten years later and underwent surgery. Partial tumor resection and anterior temporal lobectomy were performed. Histopathology revealed a glioneuronal tumor with oligodendroglia-like cells, neurocytic rosette, and perivascular pseudorosette, exhibiting an infiltrative growth pattern extending into the white matter. Genetic analysis revealed Fibroblast Growth Factor Receptor 1 mutation. The methylation profile analysis matched the low-grade glioneuronal tumor class but did not yield to any subclass category. Finally, the tumor was diagnosed as RGNT-like low-grade glioneuronal tumor with dysembryoplastic neuroepithelial tumor (DNT) features. Cases presenting with a LEAT-like clinical course and exhibiting histopathological features of RGNT are often difficult to definitively distinguish from DNT based on histological and genetic findings. Epilepsy-associated RGNT may harbor genetic profiles distinct from those of prototypical RGNTs, highlighting the need for further investigation.