Long-Term Disease Stability Achieved with Vinblastine Therapy in a Case of Diffuse Leptomeningeal Glioneuronal Tumor with QKI::RAF1 Fusion

Abstract Diffuse leptomeningeal glioneuronal tumors (DLGNTs) are rare central nervous system tumors predominantly affecting children. A case of DLGNT in a 4-year-old boy harboring the novel QKI::RAF1 fusion gene, not previously identified in DLGNT, is reported. First-line carboplatin and vincristine therapy stabilized the disease for three years, followed by temozolomide for recurrence. Tumor progression necessitated a switch to vinblastine, achieving long-term disease stability and survival for over 10 years with stable performance status. Molecular analysis showed almost whole arm deletions of 1p and gain of 1q and QKI::RAF1 fusion, a genetic alteration involving MAPK/ERK pathways. This case underscores the critical role of comprehensive molecular profiling in identifying actionable targets and guiding treatment strategies for rare tumors such as DLGNTs.