青少年多形性低度神经上皮肿瘤（PLNTY）是最近公认的一种肿瘤类型，具有惰性行为，具有特征性成像和组织分子特征。我们描述了 3 年时间内诊断为提示 PLNTY 的低级别胶质瘤的 15 例病例的临床、影像学和组织分子特征。 使用免疫组织化学（IHC）和荧光原位杂交来评估分子改变。这些肿瘤主要见于儿童（5-65 岁）。大多数患者有癫痫病史。影像学显示皮质-皮质下边界清楚的实性囊性肿瘤，伴有瘤内钙化。组织病理学显示，这是一种低度肿瘤，其中含有少突胶质细胞样细胞和 CD34 免疫阳性的星形胶质细胞。 BRAF p.V600E 突变和 FGFR2 断裂各在 6 例中观察到，而 3 例则显示 FGFR3 断裂。 FGFR2 断裂阳性 PNLTY 仅见于儿童。除两名患者死亡外，大多数病例术后均无癫痫发作。对于有癫痫病史的年轻患者，PLNTY 需要被视为实性囊性肿瘤的主要鉴别诊断。特征性临床特征、放射学、组织形态学（OLIG2、GFAP 和 CD34 的 IHC 组）与 PLNTY 中的 MAPK 改变之一相关（BRAF p.V600E、FGFR2/3 基因重排）。在资源有限的情况下，这个有限的小组可能足以进行相关诊断。© 2024。作者，获得日本脑肿瘤病理学会的独家许可。

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently recognised tumor type with indolent behaviour with characteristic imaging and histomolecular features. We describe the clinical, imaging, histo-molecular features of 15 cases diagnosed as low-grade glioma suggestive of PLNTY, over a period of 3 years. Immunohistochemistry (IHC) and fluorescence in situ hybridisation were used to assess molecular alterations. The tumors were seen predominantly in children (range 5-65 years). Most of the patients presented with history of seizures. Imaging revealed cortical-subcortical well demarcated solid-cystic tumor with intratumoral calcification. Histopathology revealed a low-grade tumor with oligodendroglia-Iike cells admixed with astrocytic cells immunopositive for CD34. BRAF p.V600E mutations and FGFR2 breakapart were observed in six cases each, while three showed FGFR3 breakapart. FGFR2 breakapart positive PLNTY were seen in children exclusively. The majority of cases were seizure free post-surgery, except two patients who succumbed to the illness. PLNTY, needs to be considered as a prime differential diagnosis in a solid-cystic tumor in a young patient with history of seizures. Characteristic clinical features, radiology, histomorphology with an IHC panel of OLIG2, GFAP and CD34 correlates with one of the MAPK alterations in PLNTY (BRAF p.V600E, FGFR2/3 gene rearrangement). In a resource limited setting, this limited panel may be sufficient for a correlative diagnosis.© 2024. The Author(s), under exclusive licence to The Japan Society of Brain Tumor Pathology.