摘要目的 探讨胸膜外肉瘤样恶性间皮瘤临床病理特点、诊断及鉴别诊断.方法 收集6例发生于胸膜外的肉瘤样恶性间皮瘤病例,分析其临床资料、组织学特征及免疫组织化学结果,进行电镜观察,并对所有病例进行随访.结果 患者男3例,女3例;年龄41~75岁,平均年龄60岁,均无石棉接触史和胸膜病变.肿瘤分别发生在腹腔(3例)、骨(2例)和颈部(1例).光镜检查显示,肿瘤细胞呈梭形或多形性,呈束状排列,形态类似于纤维瘤病、纤维肉瘤或恶性纤维组织细胞瘤.瘤细胞异型性明显,核分裂象易见.免疫组织化学结果显示,肿瘤细胞呈广谱细胞角蛋白(6/6)、calretinin (5/6)、podoplanin (6/6)、D2-40 (4/6)、波形蛋白(6/6)、WT1 (4/6)、CD10 (3/6)和平滑肌肌动蛋白(4/6) 阳性,Ki-67阳性指数25%~55%,平均>40%,而其他标志物均阴性.电镜观察:瘤细胞呈梭形、椭圆形、多边形,胞质中含有丰富的粗面内质网、细胞内管腔和更罕见的胞质内纤毛,偶尔的肿瘤细胞内出现少量的张力中间丝,肿瘤细胞间具有小的细胞间连接和从肿瘤细胞表面突出的钝小流产微绒毛.该组病例随访9个月,有1例复发,4例转移,均死亡.结论 胸膜外肉瘤样恶性间皮瘤极为少见,易与其他类型肉瘤混淆,需借助于免疫组织化学进行诊断与鉴别诊断.

abstractsObjective To investigate the morphological features, diagnosis and differential diagnosis of extrapleural sarcomatoid malignant mesothelioma (SMM).Methods Six cases of extrapleural SMM were evaluated for their clinical, histological, immunohistochemical features, and prognosis.ResultsPatients included 3 men and 3 women, with a median age of 60 years (range 41-75 years).All patients had no asbestos exposure in history and no pleural lesions.The tumors involved peritoneum (3 cases), bone (2 cases), and neck soft tissue (1 case).Histologically, the tumors were mainly composed of slender to plump spindle cells with occasional polymorphic cells, arranged in fascicular to storiform pattern or haphazardly organized, closely resembling those of fibromatosis, fibrosarcoma or malignant fibrous histiocytoma.The tumor cells were imunohistochemically positive for cytokeratin (pan,6/6), calretinin (5/6), podoplanin (6/6),D2-40 (4/6), vimentin (6/6), WT1 (4/6),CD10 (3/6), SMA (4/6), and variably positive for CK7, and CK8/18, but were negative for other linage-specific markers.The Ki-67 proliferation indexes ranged from 25% to 55%, consistent with the diagnosis of malignant mesothelioma of the sarcomatous type.Ultrastructurally, the tumor cells possessed discontinuous external lamina, cytoplasmic processes, microfilaments and desmosomal intercellular junctions.Local recurrence or metastasis was seen in 1 case and 4 cases, respectively, after surgery, and all the patients died of the disease within 9 months.Conclusions Extrapleural SMM, although rare, should be considered as a differential diagnosis among other benign or malignant sarcomatoid tumors and sarcomas.Along with clinical and radiological presentation, the combination of broad-spectrum cytokeratin, vimentin, and a series of mesothelial markers are useful for diagnosis of SMM.