脑多形性黄色瘤型星形细胞瘤的临床病理观察

Clinicopathologic study of pleomorphic xanthoastrocytoma of brain

目的探讨多形性黄色瘤型星形细胞瘤(PXA)的临床病理特征、诊断及鉴别诊断、治疗及预后。方法对南京军区南京总医院1980-2004年间6287例中枢神经系统肿瘤中的15例PXA(0．2％),以及2例会诊病例,进行临床病理学观察,免疫组织化学SP法检测8种抗体的表达:胶质纤维酸性蛋白、波形蛋白、S-100、上皮细胞膜抗原、突触素、神经微丝、CD68及CD34,获得其中10例的随访资料。结果患者年龄12—55岁,平均30．8岁,男6例,女11例。主要症状为癫痫发作、头痛、头晕等。肿瘤发生于幕上者16例,占94．1％,其中发生于颞叶者7例,占41．2％。肿瘤大小2～7 cm,平均4．3 cm,9例有囊性变。除2例会诊病例外,全切除12例,次全切除3例。随访10例,生存8例,生存时间10个月～13年7个月,平均生存6年,生存10年以上者2例。组织学特征为:单核或多核巨怪瘤细胞、梭形细胞和泡沫样瘤细胞混合而成,肿瘤中有丰富的网状纤维及淋巴细胞浸润,缺乏坏死,核分裂象无或少。胶质纤维酸性蛋白、波形蛋白及S-100蛋白免疫组织化学染色均呈弥散阳性表达,CD34阳性率为77％。1例伴有间变特征的PXA,有较多核分裂象(≥5个／10 HPF)。2例有脑实质及血管周围间隙的浸润。1例影像学检查提示肿瘤复发及脑膜播散。结论PXA属WHOⅡ级肿瘤,肿瘤全切除及组织学为典型性PXA者预后较好,少数PXA可复发及问变。瘤细胞巨大、怪异,容易误诊为WHOⅣ级的巨细胞胶质母细胞瘤,两者的鉴别要点在于PXA部分可见泡沫样瘤细胞,核分裂象无或少,缺乏坏死。瘤细胞CD34的阳性表达有助于PXA的诊断。

Objective To study the clinicopathologic features, treatment response and prognosis of pleomorphic xanthoastrocytoma （PXA）. Methods Amongst a total of 6 287 patients with central nervous system tumors encountered in Nanjing General Hospital of PLA during the period from 1980 to 2004, 15 cases of PXA were found. Two additional cases of PXA were also retrieved from the authors＇ consultation files. The clinicopathologic features of the 17 cases were studied. Follow-up information was available in 10 patients. Results The age of the patients ranged from 12 to 55 years （ mean = 30. 8 years）. The male-to-female ratio was 6： 11. Commonest clinical symptoms included seizures, headaches and dizziness. The tumors in 16 patients were located in the superficial cerebral cortex （94. 1% ）. Seven cases （41.2%） involved the temporal lobe. The size of the tumors varied from 2 to 7 cm （mean = 4. 3 cm ）. Cystic degeneration was noted in 9 cases. For those in-house cases, total tumor excision was performed in 12 patients and subtotal tumor excision was performed in 3 patients. Amongst the 10 patients with follow-up information available, 8 were alive. The post-operative survival ranged from 10 months to more than 13 years （mean survival = 6 years）. Classic histopathologic features included an admixture of mononuclear cells, bizarre multinucleated giant cells, spindled cells and lipid-rich vacuolated cells. The tumor cells were associated with abundant lymphocytes and reticulin fibers. They showed little tumor necrosis or mitotic activity. Immunohistochemical study demonstrated diffuse positive staining for glial fibrillary acidic protein, vimentin and S-100 protein. Seventy-seven percent of the cases also showed positive staining for CD34. One case had anaplastic transformation, with increased mitotic activity （ mitotic count ≥ 5 per 10 high power fields）. The tumor cells infiltrated the underlying cerebral cortex with extension into perivascular spaces in 2 cases.Radiologi examination revealed tumor recurrence with diffuse leptomeningeal spread in 1 case.Conclusions PXA is low-grade glial tumor,corresponing to WHO grade Ⅱ.Cases with typical pathologic features and total tumor excision carry favorable prognosis.Local recurrence or anaplastic transformation may occur in rare examples.Histologically.PXA can be mistaken as WHO grade Ⅳ giant cell glioblastoma,as both entities possess tumor giant cells.PXA however harbors lipidized astocytes and lacks coagulatiove tumor necrosis and high mitotic activity.Frequent expression of CD34 in PXA is also helpful in differential diagnosis.