Objective To explore the clinical pathological and molecular genetic characteristics of polymorphous low-grade neuroepithelial tumor of the young （PLNTY）. Methods A total of 16 patients with PLNTY were recruited as research subjects， who underwent surgical treatment at Beijing Tiantan Hospital affiliated to Capital Medical University from May 2021 to May 2023. The clinical and imaging data were collected. Hematoxylin eosin staining， immunohistochemistry staining， and gene sequencing were used to detect morphological and molecular genetic changes in tumor tissue. Patients were followed up on symptom improvement， the presence of radiotherapy and chemotherapy， and tumor recurrence through telephone and imaging follow-up. Results The median age of onset was 24 years in the 16 cases of PLNTY， and the male-to-female ratio was 1∶1. Five cases （5/16） presented with acute onset （onset time ＜ 3 months）. The clinical symptoms are mainly characterized by varying degrees of epileptic seizures. Eight cases （8/16） were located in the temporal lobe， and 5 cases （5/16） were located in the parietal occipital lobe. Enhanced magnetic resonance imaging scan showed no significant enhancement in 11 cases （11/16）， mild heterogeneous enhancement in 3 cases （3/16）， and significant heterogeneous enhancement in 2 cases （2/16）. Fourteen patients （14/16） showed improvement in postoperative epilepsy symptoms， with 1 case experiencing recurrence. The histopathological results showed that the tumor showed invasive growth， located in the cortex and subcortical white matter， with pleomorphic and oligodendrocyte like cell morphology and branching small blood vessels. Twelve cases （12/16） were accompanied by calcification. One case of recurrent resected specimen showed malignant transformation， characterized by increased local cell density， visible nuclear mitotic figures， neovascularization， and palisading necrosis. The immunohistochemical staining results of 16 cases of tumors showed diffuse positive expression of glial fibrillary acidic protein （GFAP）， oligodendrocyte transcription factor 2 （Olig2）， and CD34， while synaptophysin was negatively expressed. Among them， 14 cases （14/16） had a Ki67 proliferation index ≤ 4%， and the Ki67 proliferation index of malignant transformation cases was 20%. Second-generation sequencing results of 7 cases showed that BRAF or FGFR molecular mutations were predominant， with three cases （3/7） showing methylation of the O6-methylguanine-DNA methyltransferase promoter （MGMT）； FGFR3：：TACC3 fusion with TERT promoter mutation was detected in 1 primary and recurrent case， and chromosome 10 deletion and CDK4 and MDM2 amplification were observed in the recurrent cases. Conclusions PLNTY is common in adolescents and is a long-term epilepsy related tumor， commonly found in the temporal and parietal occipital lobes. The tumor shows invasive growth， with visible pleomorphic and oligodendrocyte cell components. CD34 is diffusely positive， and molecular changes are mainly BRAF or FGFR variants. The prognosis is mostly favorable with significant improvement in postoperative seizure symptoms. Individual cases may experience malignant transformation after recurrence， and molecular genetic results show FGFR3：： TACC3 fusion with TERT promoter mutation. It is important for clinicians to thoroughly assess clinical， pathological characteristics and molecular genetic alterations of PLNTY and be vigilant.