Objective: To investigate the clinicopathological features, diagnosis and prognosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Methods: Five cases of DLGNT diagnosed from January 2016 to January 2020 were collected from Xuanwu Hospital, Capital Medical University. The clinical features, histopathologic characteristics, immunohistochemical and molecular genetic findings and prognosis were analyzed and the relevant literature was reviewed. Results: The five patients (two males and three females) were aged 2 to 52 years (median 11 years), and had history of increased intracranial pressure (headache and vomiting) or limb weakness. Three of them were younger than 16 years of age. The imaging studies showed diffuse intracranial and intraspinal nodular leptomeningeal thickening and enhancement, with or without parenchymal involvement. At times there were associated small cyst-like lesions. Imaging interpretations were inflammatory lesions in three cases and space occupying lesions in two. Microscopically, in three cases the tumors showed low to moderate cellularity, consisting of relatively monomorphous oligodendrocyte-like cells arranged in small nests or diffusely distribution. No mitosis and necrosis were observed. In two cases there were increased cellularity with a diffuse honeycomb pattern. The tumor showed mild to moderate polymorphism with hyperchromatic nuclei. Mitosis, endothelial vascular proliferation and glomeruloid vessels were seen. Necrosis was absent. The tumor cells in all five cases were positive for synaptophysin,Olig2 and negative for IDH1 and H3 K27M. GFAP was focally positive in four cases and only one case expressed NeuN partly. The Ki-67 labeling index was 1%-35%. BRAF fusion was detected in four cases. Genetic analysis showed solitary 1p deletion in two cases (2/5), while all cases were negative for 1p/19q co-deletion (0/5). The five patients were followed up for 13 to 28 months (median 15 month). One patient died after 27 months. There was no evidence of tumor progression in the remaining four patients. Conclusions: DLGNT is rare and easily confused with other central nervous system tumors and inflammatory lesions. Therefore, the diagnosis of DLGNT should be made based on comprehensive information including imaging, morphologic and corresponding immunohistochemical examinations and molecular genetics to avoid misdiagnosis and delay in management.
目的： 探讨弥漫性软脑膜胶质神经元肿瘤（diffuse leptomeningeal glioneuronal tumor）的临床病理特征、诊断及预后。 方法： 收集首都医科大学宣武医院病理科2016年1月至2020年1月术后及病理会诊确诊的5例弥漫性软脑膜胶质神经元肿瘤，观察其临床特征、组织学形态、免疫组织化学表型、分子遗传学特征以及预后，并结合相关文献复习。 结果： 5例患者中2例男性，3例女性。年龄2~53岁（中位年龄11岁），其中小于16岁患者3例。临床主要表现为颅内压增高（头痛、呕吐）或肢体无力。磁共振成像（MRI）均提示颅内和椎管内弥漫性结节性软脑膜增厚和强化，部分囊性变，伴或不伴脑实质受累。临床诊断炎性病变3例，描述性占位性病变2例。光镜下，肿瘤在软脑膜内呈弥漫性或巢团状生长，5例中3例表现为低或中等密度的形态单一的少突胶质细胞样肿瘤细胞，未见坏死和核分裂象；2例细胞密度较高，轻-中度异型，核大深染，核分裂象可见，并见肾小球样微血管增生。免疫表型：5例肿瘤均突触素、Olig2阳性，IDH1、H3 K27M阴性；4例胶质纤维酸性蛋白（GFAP）局灶阳性，1例NeuN部分阳性，Ki-67阳性指数1%~35%。分子遗传学显示：4例BRAF融合基因阳性，2例染色体1p缺失、19q完整，3例未见到1p及19q杂合性共缺失。5例患者术后随访13~28个月（中位随访时间15个月），1例患者27个月后死亡，余4例患者无肿瘤进展证据。 结论： 弥漫性软脑膜胶质神经元肿瘤罕见，且极易与其他中枢神经系统肿瘤和炎性病变相混淆，应结合临床影像学、形态学、相应的免疫组织化学染色和分子遗传学综合判断，以避免误诊耽误治疗。.