Diffuse Leptomeningeal Glioneuronal Tumor: A Systematic Review Highlighting Molecular Heterogeneity and Survival Outcome

<b>Background/Objectives</b>: Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare central nervous system neoplasm characterized by leptomeningeal dissemination and heterogeneous clinical and molecular features. Owing to its rarity, the prognostic relevance of clinical, radiological, and molecular factors remains poorly defined. This systematic review aimed to comprehensively summarize the clinicopathological characteristics, molecular landscape, treatment strategies, and survival outcomes of patients with DLGNT. <b>Methods</b>: A systematic literature search was conducted in PubMed, Embase, Scopus, and Google Scholar to identify published cases of DLGNT. Studies reporting individual patient data were included. Clinical, molecular, treatment, and survival data were pooled. Overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan-Meier method, with subgroup analyses according to clinical and molecular variables. <b>Results</b>: Seventy-five patients were included. Most patients were pediatric, and spinal leptomeningeal dissemination and hydrocephalus were frequent. BRAF alterations, most commonly KIAA1549::BRAF fusion, were frequently identified, although no molecular marker predicted survival. The median OS was 89 months, and the median PFS was 30 months. Surgical resection was associated with significantly longer OS compared with biopsy only, while a trend toward longer PFS was observed. Survival outcomes did not differ significantly according to age group, BRAF status, chemotherapy, or radiotherapy. <b>Conclusions</b>: DLGNT is a rare and heterogeneous tumor with variable presentation and prolonged survival in selected patients. Although surgical resection may be associated with improved survival, interpretation is limited by selection bias. No single molecular alteration reliably predicts prognosis, highlighting the need for prospective multicenter studies with standardized molecular profiling.