摘要： 目的   探讨小脑富脂质髓母细胞瘤临床病理学特征。方法   对一例小脑富脂质髓母细胞瘤患者临床表现、影像学特点，以及组织病理学和免疫组织化学特征进行回顾性分析，并复习相关文献。结果   男性患者，26 岁。临床表现为反复头痛，伴头晕、恶心、呕吐。MRI 显示病灶填充第四脑室，T1WI呈均匀低信号、T2WI呈不均匀高信号，增强T1WI扫描病灶呈明显均匀强化，边界清晰。手术后光学显微镜下观察肿瘤细胞弥漫增生，大小一致，胞质淡染，呈弱酸性或嗜双色，核圆形或卵圆形，染色质细腻，核仁可见，核分裂象易见；间质中含有丰富的薄壁血管；富于脂质的细胞呈灶性分布。免疫组织化学染色肿瘤细胞CD56 和突触素弥漫阳性，局灶表达神经微丝，弱表达少突胶质细胞系转录因子?2；不表达巢蛋白、神经元核抗原、S-100 蛋白、胶质纤维酸性蛋白和上皮膜抗原；TP53 染色阳性（约10％），Ki-67 抗原标记指数约为40％。结论   发生于小脑的富脂质髓母细胞瘤为临床罕见的中枢神经系统肿瘤，影像学呈现发生于小脑蚓部向第四脑室生长的占位性病变；病理学表现肿瘤细胞由高度密集的一致圆形细胞组成，具有灶性脂肪样细胞分化，应注意与小脑脂肪神经细胞瘤和室管膜瘤等相鉴别。

关键词: 髓母细胞瘤, 小脑肿瘤, 磁共振成像, 病理学, 免疫组织化学

Abstract: Objective To explore the clinicopathological features of cerebellar lipidized medulloblastoma. Methods The clinical manifestations， neuroimaging, histopathological and immunohistochemical features were analysed in one case of lipidized medulloblastoma in the cerebellar vermis. Related literatures were reviewed. Results A 26-year-old man presented with intermittent headache，accompanied by dizziness, nausea and vomiting. The magnetic resonance imaging (MRI) demonstrated a mass located the cerebellar vermis convex to the fourth ventricle. The tumor with well-demarcated boundary was homogeneous hypointense on T1 weighted and heterogeneous hyperintense on T2 weighted images, and enhanced brilliantly and homogenously on contrast. The patient subsequently underwent gross total mass resection. Microscopically，there was diffuse infiltration by high cellularity of tumor cells. The cytoplasm were thin eosinophilic to amphophilic. The neoplastic cells showed round to oval hyperchromatic nuclei with a delicately stippled chromatin and occasional conspicuous nucleoli and numerous mitotic figures were also present. Thin-wall vascular proliferation was detected. Lipid-laden cells were focally distributed in tumor tissue. On immunohistochemical examination, the neoplasm was reactive for CD56 and synaptophysin (Syn), focally positive for neurofilament protein (NF), weakly positive for oligodendrocyte lineage transcription factor 2 (Olig-2), and negtive for nestin, neuronal nuclei (NeuN), S-100 protein (S-100), glial fibrillary acidic protein (GFAP) and epithelial membrane antigen (EMA). TP53 protein was over expressed in 10% of tumor cells. Ki-67 antigen labeling index were about 40% . Conclusion Cerebellar lipidized medulloblastoma is rare. Neuroimaging showed space occupying lesion in cerebellar vermis. Histologically, the tumor cells were consisted of monotonous, round cells with focal accumulations of lipidized cells. The differential diagnosis include liponeurocytoma and ependymoma and so on.

Key words: Medulloblastoma, Cerebellar neoplasms, Magnetic resonance imaging, Pathology, Immunohistochemistry