Abstract:

Objective  To investigate the clinicopathological features, immune phenotype and gene mutation characteristics, and diagnosis or differential diagnosis of anaplastic pleomorphic xanthoastrocytoma (PXA).  Methods and Results  A 11 - year- old male patient presented with more than half month of headache, and left upper limb weakness. Cranial CT and MRI revealed a large space-occupying lesion in the right parietal lobe and basal ganglia which was suggested as glioma. During operation the tumor was examined. It was a cystic-solid lesion. The solid part was soft and greyish yellow with rich blood supply and without membrane, and the boundary was clear. Intraoperative freezing pathologic examination showed the tumor was a low grade glioma. The right parietal glioma was completely removed piece by piece under the microscopy. Histologically, the tumor cells were polymorphism, including spindle or round astrocytes, monocytes and multinuclear tumor giant cells. Mitoses were rarely seen. Differentiation of mature neuronal cells or ganglion cells with lymphocyte infiltration were seen in focal region. In some regions, tumor cells were anaplastic, and cellularity were increased. Atypical round or spindle cells were seen, and atypical mitoses > 5/10 high power field (HPF) were found.  icrovascular proliferation, perivascular pseudorosettes and localized necrosis were also evident. Immunohistochemically, tumor cells were positive for glial fibrillary acidic protein (GFAP), BRAF V600E, S-100 protein (S-100), CD34, synaptophysin (Syn), non- phosphorylation neurofilament heauy chain SMI- 32 and P53, but negative for isocitrate dehydrogenase 1(IDH1), neurofilament protein (NF) and epithelial membrane antigen (EMA). Ki - 67 labeling index was about 3% in low grade tumor cells, while Ki-67 labeling index was about 30% in high grade tumor cells. In reticular fibre tissue staining, a lot of reticular fibre tissue were seen. BRAF V600E heterozygous mutation c.1799A > T was detected by Sanger sequencing.  Conclusions  Anaplastic PXA in grade Ⅲ is defined as mitoses > 5/10 HPF in World Health Organization (WHO) classification of tumors of the central neuvous system, 2016. Its prognosis is worse than grade Ⅱ tumor. The differential diagnosis from glioblastoma (GBM), pilocytic astrocytoma (PA) and ganglioglioma (GG) should be kept in mind, because all of them having some overlaps in clinicopathological presentations, imaging manifestation, immunophenotype features and genetic mutation, but quite different in their biological behavior, treatment and prognosis.

Key words: Xanthomatosis, Astrocytoma, Anaplasia, Immunohistochemistry, Pathology

摘要：

目的 报道1 例男性间变型多形性黄色瘤型星形细胞瘤患儿的临床资料，探讨其临床病理学、免疫表型、基因突变特征，以及诊断与鉴别诊断要点。  方法与结果男性患儿，11 岁，头痛伴左上肢无力15 d。头部CT 和MRI显示右侧颞叶和基底节区巨大占位性病变，提示胶质瘤。遂行右侧颞叶和基底节区占位性病变切除术，术中可见肿瘤呈囊实性，实性部分呈灰黄色，质地柔软，血供丰富，无包膜，与周围组织界限清晰。术中冰冻病理学提示低级别胶质瘤，遂分块全切除肿瘤。组织学形态观察，肿瘤细胞呈多形性，由梭形和圆形星形胶质细胞以及单核细胞和多核瘤巨细胞组成，核分裂象罕见；局部可见较成熟的神经元或节细胞分化成分，伴淋巴细胞浸润；部分区域肿瘤细胞呈间变特征，细胞密度增加，异型性明显，以圆形和梭形细胞为主，核分裂象> 5 个/10 高倍视野，血管内皮细胞增生，伴血管周围假“ 菊形团”样结构，局灶性坏死。免疫组织化学染色，低级别肿瘤细胞胞质表达胶质纤维酸性蛋白（GFAP）和BRAF V600E、胞质和胞核表达S?100 蛋白、胞膜表达CD34，少数肿瘤细胞胞质表达突触素和非磷酸化神经丝重链SMI?32，Ki?67 抗原标记指数为3%；低级别和高级别肿瘤细胞胞核均表达P53；高级别肿瘤细胞胞质表达GFAP 和BRAF V600E，Ki?67 抗原标记指数为30%。网织纤维染色可见肿瘤细胞周围包绕基底膜样物质。基因检测显示，低级别和高级别肿瘤均存在BRAF V600E 杂合突变。 结论 2016 年世界卫生组织中枢神经系统肿瘤分类将间变型多形性黄色瘤型星形细胞瘤定义为核分裂象> 5 个/10 高倍视野，属WHOⅢ级，预后较WHOⅡ级多形性黄色瘤型星形细胞瘤差。鉴别诊断主要包括胶质母细胞瘤、毛细胞型星形细胞瘤和节细胞胶质瘤，尽管上述肿瘤临床表现、组织学形态、免疫表型和基因突变有重叠，但生物学行为、治疗及预后各异。

关键词: 黄瘤病, 星形细胞瘤, 间变, 免疫组织化学, 病理学