脂肪样星形细胞瘤

Clinicopathological features of cerebral lipoastrocytoma

目的探讨脂肪样星形细胞瘤的临床病理学特征、免疫表型、诊断与鉴别诊断、治疗及预后。方法与结果男性患者,48岁。临床表现为左手无名指及小指麻木、活动不利。MRI显示右顶叶占位性病变,伴囊性变,实性区域明显强化。立体定向下行右顶叶肿瘤全切除术。光学显微镜观察肿瘤呈低级别星形细胞瘤形态,散在一些胞质丰富、核仁明显的神经元样细胞;以脂肪空泡形成为特征,形似成熟的脂肪细胞,呈灶状相互融合,似微囊性变。肿瘤细胞表达胶质纤维酸性蛋白、S-100蛋白、WT-1蛋白和少突胶质细胞转录因子2,以及神经元标志物突触素、微管相关蛋白-2、神经微丝蛋白、神经元特异性烯醇化酶和CD34,不表达异柠檬酸脱氢酶1,P53蛋白呈弱阳性(5%),Ki-67抗原标记指数约为1%。术后随访20个月,肿瘤无复发。结论脂肪样星形细胞瘤为临床少见肿瘤,组织病理学呈低级别星形细胞瘤形态,伴显著脂肪样细胞分化,亦可伴神经元样分化。明确诊断需结合病理学形态及免疫表型,同时应注意与其他伴脂肪样细胞分化或黄色瘤样变的神经上皮组织肿瘤相鉴别。

Objective To explore the clinicopathological features, immune phenotype, diagnosis and differential diagnosis, treatment and prognosis of cerebral lipoastrocytoma. Methods Retrospective analysis of the clinical manifestations, histopathologieal and immunohistochemical features were conducted in one case of cerebral lipoastrocytoma. Results A 48- year-old male presented with numbness and inflexibility of the fourth and little fingers of his left hand over the previous 2 weeks. Cranial MRI revealed a space- occupying lesion with cystic degeneration in the right parietal lobe that showed obvious enhancement after contrast administration. The patient subsequently underwent eraniotomy with stereotactic gross total excision of the lesion. Adjuvant chemotherapy and radiation therapy were not administered. Histologically the tumor showed classical features of low-grade astrocytoma, including a few scattered medium-large neuron-like cells with prominent nucleoli and abundant cytoplasm. Most notably, the glial cells contained fat droplets or vacuoles giving an appearance of mature adipocytes. Focally microcystie change was evident resulting from adipocyte-like cells fusion with each other. Immunohistoehemieally, the tumor cells were reactive for glial fibrillary acidic protein （GFAP） and S-100 protein （S-100）, focally positive for WT-1, weakly positive for oligodendrocytes transcription factor-2 （Olig-2）, and negative for isoeitrate dehydrogenase 1 （IDH1）. Meanwhile, the tumor cells also expressed several neuronal markers including synaptophysin （Syn）, mierotube-associated protein-2 （MAP-2）, neurofilament （NF）, neuron specific enolase （NSE） and CD34. P53 protein was weakly expressed in 5% of tumor cells. Ki-67 labeling index was low （1%）. The patient remained well without recurrence 20 months after surgery. Conclusions Cerebral lipoastrocytoma is an extremely rare tumor. Histologically, the tumor showed classical features of low-grade astroeytoma and extensive lipomatous differentiation. Interestingly, the present ease also showed neuronal differentiation confirmed by I^ositive staining with neuronal markers. Diagnosis needs to be combined with pathological morphology and immune phenotype, which can distinguish from other neuroepithelial tumors with fat cell differentiation or xanthomatous change.