Abstract: Background  Subependymal giant cell astrocytoma (SEGA) is a rare kind of central nervous system tumor typically occurring in children or adolescents under the age of 20. The tumor commonly arises in the region of the foramen of Monro. Most SEGA patients present distinctive histopathological and immunohistochemical characteristics.  Methods  The clinical features, histopathological findings and immunohistochemical staining in one case of SEGA were analyzed, and the diagnosis and differential diagnosis of this disease with literature review were studied.  Results  A 13-year-old female patient presented dizziness, headache and vomiting. Cranial MRI examination showed abnormal signals in the left lateral ventricle near the foramen of Monro, and exhibited heterogeneous enhancement after contrast. Histologically, the tumor was composed of clustering of fibrillated spindle cells and giant cells with abundant cytoplasm, and they were mixed. Glassy hyaline cytoplasm and eccentric vesicular nuclei with prominent nucleoli were frequently seen in the giant tumor cells. Some of the giant cells appeared to resemble gemistocytic astrocytes or ganglion cells. Considerable nuclear pleomorphism and multinuclear cells were frequently seen. There was no significant microvascular proliferation or necrosis. Immunohistochemical findings showed diffuse and strong positivity in tumor cells for vimentin (Vim), and partial positivity for S-100 protein (S-100), epithelial membrane antigen (EMA) and glial fibrillary acidic protein (GFAP). A few giant tumor cells were positive for synaptophysin (Syn), but negative for neurofilament protein (NF), neuronal nuclei (NeuN) and cytokeratin (CK). Ki-67 labeling index was very low (< 1%).  Conclusions  SEGA is a benign central nervous system tumor (WHOⅠ). It has distinctive clinical and histopathological features, and should be differentiated from gemistocytic astrocytoma, ependymoma, gangliocytoma and giant cell glioblastoma.

Key words: Astrocytoma, Ependyma, Pathology, Immunohistochemistry

摘要： 研究背景 室管膜下巨细胞型星形细胞瘤为中枢神经系统少见肿瘤，多发生于20 岁以下的儿童或青少年，好发于侧脑室室间孔区，大多数患者具有独特的组织病理学和免疫组织化学特征。方法与结果 女性患者，13 岁。临床表现为头晕、头痛伴呕吐；MRI显示左侧侧脑室室间孔区异常信号，增强后病灶呈不均匀明显强化。组织学观察肿瘤细胞大小不一、形态多样，大片束状排列的梭形细胞背景中可见成片的胖细胞样肿瘤细胞，胞质丰富呈毛玻璃样，以及少量节细胞样巨细胞和多核瘤巨细胞；肿瘤细胞胞核呈空泡状、核仁明显，无明显血管内皮增生或坏死区域；肿瘤细胞弥漫表达波形蛋白，部分表达S-100蛋白、上皮膜抗原和胶质纤维酸性蛋白，少量胖细胞样肿瘤细胞表达突触素，不表达神经微丝蛋白、神经元核抗原和细胞角蛋白，Ki-67 抗原标记指数< 1%。结论 室管膜下巨细胞型星形细胞瘤为中枢神经系统良性肿瘤（WHOⅠ级），具有独特的临床表现和组织学特征，需注意与肥胖细胞型星形细胞瘤、室管膜瘤、神经节细胞胶质瘤和巨细胞型胶质母细胞瘤等相鉴别。

关键词: 星形细胞瘤, 室管膜, 病理学, 免疫组织化学