小肠骨外尤因肉瘤/外周原始神经外胚层肿瘤临床病理观察

摘要

目的：探讨小肠骨外尤因肉瘤/外周原始神经外胚层肿瘤(extraskeletal Ewing sarcoma/peripheral primitive neuroectodermal tumor, E-EWS/pPNET)的临床病理学特点、诊断及鉴别诊断。方法对1例小肠E-EWS/pPNET患者的临床特征及组织形态学和免疫组织化学染色进行分析,并复习相关文献。结果男性患者,61岁。临床表现为十二指肠腔内占位,累及胆总管下端及部分胰腺。镜下观察肿瘤组织由形态一致的小圆或卵圆形细胞所组成,胞质较少,细胞核呈圆形或类圆形、染色质浓染,病理性核分裂像易见,肿瘤细胞呈弥漫性实性片状密集分布,局部可见Homer-Wright菊形团样结构,伴有大片坏死。免疫组化显示肿瘤细胞波形蛋白、CD99蛋白、神经元特异性烯醇化酶、突触素及CD56表达阳性,角蛋白CK、CK20、CK8/18、癌胚抗原、白细胞共同抗原、结蛋白、嗜铬素A、CD117、CD34、S-100蛋白、HMB45、α-inbin、胰岛素、胃泌素、降钙素、胰高血糖素均阴性, Ki67细胞增殖指数90%,高碘酸-雪夫(PAS)染色阴性。结论小肠E-EWS/pPNET是一种非常少见的小圆细胞高度恶性肿瘤,诊断主要依据病理形态学特征及免疫组化标记, CD99、CD56及NSE等神经内分泌标记物阳性并结合细胞遗传学特点对鉴别诊断有重要意义。%Objective To investigate clinicopathological characteristics and differential diagnosis of Ewing’s Sarcoma/primitive neuroectodermal tumor(EWS/PNET) in small intestine. Methods One case of EWS/PNET in small intestine was studied by clinicopathologic features, histochemistry, and immunohistochemistry, with review of the relevant literatures. Results The patient was a 61 year-old man. The clinical symptom was duodenal masses with invading common bile duct and partial pancreas. Histologically, the tumor cells were diffusive and uniform patchy intensive, and the tumor cells contained only a few cytoplasm. Many undifferentiated round cells with round or irregular hyperchromatic nuclei. Abundant mitotic figures were present. The cells distributed diffusively or formed lobulated structures (Homer-Wright rosette) with extensive necrosis. Immunohistochemical analysis showed positive expression for Vimentin, CD99, Neuron specific enolase(NSE), Syn and CD56 protein in tumor cells. The tumor cells presented negative for cytokeratin(CK), CK20, CK8/18, CEA, LCA, Desmin, CgA, CD117, CD34, S-100 protein, HMB45,α-inbin, insulin, gastrin, calcitonin and glucagon. The Ki67 labeling index was 90%. PAS specific stain was negative. Conclusion EWS/PNET in small intestine is a rare and highly malignant small round cell tumor, and the diagnosis must based on pathologic findings and immunohistochemical phenotypes. Positive expression for CD99, CD56 and NSE combine with molecular genetic study may be valuable in differential diagnosis.