摘要： 研究背景 毛细胞型星形细胞瘤是常见于小脑的低级别胶质瘤，好发于儿童和青少年。本文报告1 例临床罕见、发生于成人幕上的毛细胞型星形细胞瘤病例，其病理形态与典型的毛细胞型星形细胞瘤略有不同：脑组织大部分区域肿瘤细胞围绕玻璃样变性小血管呈单层排列，即所谓的血管中心性生长。本文拟探讨含有血管中心性排列特征的毛细胞型星形细胞瘤的临床、影像学及病理学特征，并讨论其与相关肿瘤的临床病理学鉴别要点，以提高对此类肿瘤的诊断与鉴别诊断能力。方法与结果 男性患者，28岁。临床表现为反复发作的癫痫大发作，抗癫痫药物治疗无效，脑电图检查未发现典型的癫痫样放电或局灶性δ 波。影像学检查以额叶皮质边界清楚的囊性病变伴壁结节为特征性表现。术中可见肿瘤组织质地较韧，表浅为囊性结构、深部呈实质性结构。光学显微镜下观察肿瘤细胞胞核呈圆形、卵圆形，胞质两端突起细长毛发状，围绕玻璃样变性小血管单层排列，部分区域肿瘤细胞胞核伸展呈梭形，束状致密排列或疏松星网状排列，偶见 Rosenthal纤维和嗜酸性颗粒小体形成。肿瘤细胞弥漫表达胶质纤维酸性蛋白、波形蛋白、S-100 蛋白、巢蛋白和CD56，局灶性表达Olig2，不表达上皮膜抗原、异柠檬酸脱氢酶1 、P53 、神经元核抗原、神经微丝蛋白、突触素及CD34，Ki-67抗原标记指数约为1%。病理诊断：左侧额叶含有血管中心性排列特征的毛细胞型星形细胞瘤（WHOⅠ级）。术后未行放射治疗或药物化疗，随访1 年余未出现癫痫发作，肿瘤无复发。结论 毛细胞型星形细胞瘤好发于儿童，以小脑多见，发生于成人及幕上者少见，含有血管中心性排列特征的毛细胞型星形细胞瘤形态特殊，诊断时应注意与毛细胞黏液型星形细胞瘤、星形母细胞瘤、血管中心型胶质瘤、皮质室管膜瘤及乳头状型胶质神经元肿瘤相鉴别。

关键词: 脑肿瘤, 星形细胞瘤, 毛细胞, 听觉

Abstract: Background  Pilocytic astrocytoma (PA) is a low-grade glioma that occurs mainly in the cerebellum of children and young adults. This article is to report a rare case of PA with angiocentricarrangement in the supratentorial region of a 28-year-old male. The pathomorphism of this tumor isdifferent from that of typical PA, since most tumor cells grow in single layer around the hyalinized degenerative vessels, that is to say, angiocentric pattern. This paper aims to discuss the clinical, imaging and pathological features of PA with angiocentric arrangement and clinicopathological differentiations from relevant tumors, so as to improve the ability of diagnosing and differentiating this kind of tumor. Methods and Results  A 28-year-old male with no significant past history presented with repeated grand mal seizures and did not recover in the treatment with antiepileptic drugs. Physical and neurological examinations were normal. Electroencephalography (EEG) found no typical epileptic wave or focal δ wave. CT and MRI showed a superficial cystic mass with a mural nodule and clear boundary in the left frontal cortex. During the resection of the tumor, the lesion was identified as cystic structure on the surface and solid structure within the cyst wall. Optical microscopy findings revealed that tumour cells with round or oval nuclei and cytoplasm showing slender hair-like protuberance of both ends were arranged in single layer around hyalinized blood vessels. Some tumor cells with fusiform nuclei showed compact fascicles or loose stellate reticulum. Rosenthal fibers and eosinophilic granular bodies were occasionally seen. According to immunohistochemical staining, the tumor cells were diffusely positive for glial fibrillary acidic protein (GFAP), Vimentin (Vim), S-100 protein (S-100), Nestin, CD56, and focally positive for Olig2, while the tumor cells were negative for epithelial membrane antigen (EMA), isocitrate dehydrogenase 1 (IDH1), P53, neuronal nuclei antigen (NeuN), neurofilament protein (NFP), synaptophysin (Syn) and CD34. The overall MIB-1 labeling index was 1% . According to these findings, the tumor was diagnosed as PA with angiocentric arrangement in the left frontal lobe (WHO Grade Ⅰ). The patient was not given further treatment including radiotherapy or chemotherapy after surgery. One year follow-up showed no onset of seizures or tumor recurrence. Conclusion  This is the first case report of a cerebrellum PA with extensive angiocentric arrangement in an adult. According to the clinical and histomorphological (including the angiocentric arrangement) features, the differential diagnosis should include pilomyxoid astrocytoma, astroblastoma, angiocentric glioma, cortical ependymoma and papillary glioneuronal tumor.

Key words: Brain neoplasms, Astrocytoma, Hair cells, auditory