Objective:To investigate the clinicopathological and molecular genetic characteristics of diffuse gliomas with the features of polymorphous low-grade neuroepithelial tumor of the young (PLNTY) and their prognostic values.Methods:A retrospective analysis was performed on 14 cases of diffuse gliomas with PLNTY features diagnosed at the First Affiliated Hospital of Fujian Medical University, Fuzhou, China from June 2020 to August 2024. Their clinicopathological characteristics were examined, and their molecular genetic and epigenetic features were assessed using next-generation sequencing (NGS) and methylation analysis. Factors influencing prognosis were also analyzed.Results:Among the 14 patients, there were 8 males and 6 females, aged 3-62 years, median 29 (9, 50) years. All cases were initially diagnosed as low-grade diffuse gliomas histologically but exhibited the histological and immunohistochemical features of PLNTY. At the molecular level, all cases showed molecular abnormalities involving the mitogen-activated protein kinase pathway, including 5 cases with FGFR3-TACC3 (F3T3) fusion, 3 cases with FGFR2 fusion, 5 cases with BRAF V600E mutation, and 1 case with FGFR1 mutation. Among them, TERT promoter mutations were frequently observed in tumors with F3T3 fusion (5/5), while NCOR2 in-frame insertion mutations were prominent in tumors with non-F3T3 fusions. Clinical follow-up showed recurrence in 3 cases, all of which had F3T3 fusion and concurrent TERT promoter mutations. Prognostic analysis confirmed that F3T3 fusion with concurrent TERT promoter mutation was associated with poor prognosis.Conclusions:Diffuse gliomas with PLNTY features exhibit heterogeneity in clinicopathology and molecular genetics, with FGFR3/FGFR2 fusions and BRAF/FGFR1 mutations as the most common molecular alteration. They often have concurrent F3T3 fusion and TERT promoter mutations, which are related to poor prognosis. The possibility of molecular glioblastoma should be considered for these tumors. It is thus recommended to perform genetic testing on diffuse gliomas with PLNTY features in order to facilitate integrated diagnosis and provide molecular evidence for accurate evaluation of prognoses.

Objective:To investigate the clinicopathological and molecular genetic characteristics of diffuse gliomas with the features of polymorphous low-grade neuroepithelial tumor of the young (PLNTY) and their prognostic values.Methods:A retrospective analysis was performed on 14 cases of diffuse gliomas with PLNTY features diagnosed at the First Affiliated Hospital of Fujian Medical University, Fuzhou, China from June 2020 to August 2024. Their clinicopathological characteristics were examined, and their molecular genetic and epigenetic features were assessed using next-generation sequencing (NGS) and methylation analysis. Factors influencing prognosis were also analyzed.Results:Among the 14 patients, there were 8 males and 6 females, aged 3-62 years, median 29 (9, 50) years. All cases were initially diagnosed as low-grade diffuse gliomas histologically but exhibited the histological and immunohistochemical features of PLNTY. At the molecular level, all cases showed molecular abnormalities involving the mitogen-activated protein kinase pathway, including 5 cases with FGFR3-TACC3 (F3T3) fusion, 3 cases with FGFR2 fusion, 5 cases with BRAF V600E mutation, and 1 case with FGFR1 mutation. Among them, TERT promoter mutations were frequently observed in tumors with F3T3 fusion (5/5), while NCOR2 in-frame insertion mutations were prominent in tumors with non-F3T3 fusions. Clinical follow-up showed recurrence in 3 cases, all of which had F3T3 fusion and concurrent TERT promoter mutations. Prognostic analysis confirmed that F3T3 fusion with concurrent TERT promoter mutation was associated with poor prognosis.Conclusions:Diffuse gliomas with PLNTY features exhibit heterogeneity in clinicopathology and molecular genetics, with FGFR3/FGFR2 fusions and BRAF/FGFR1 mutations as the most common molecular alteration. They often have concurrent F3T3 fusion and TERT promoter mutations, which are related to poor prognosis. The possibility of molecular glioblastoma should be considered for these tumors. It is thus recommended to perform genetic testing on diffuse gliomas with PLNTY features in order to facilitate integrated diagnosis and provide molecular evidence for accurate evaluation of prognoses.