摘要目的:探讨胃SWI/SNF复合体缺失的未分化癌/横纹肌样癌（gastric SWI/SNF complex-deficient undifferentiated/rhabdoid carcinomas）的临床病理特征、免疫表型、鉴别诊断及预后。方法:收集2017—2018年复旦大学附属肿瘤医院2例胃SWI/SNF复合体缺失的未分化癌/横纹肌样癌患者的临床资料，行苏木精-伊红染色及免疫组织化学染色，并复习相关文献。结果:2例患者均为男性，年龄分别为60和74岁，均以上腹部隐痛为首发症状。例1肿瘤位于食管胃交界处，例2肿瘤位于贲门、胃底及胃体上部小弯侧后壁，均表现为溃疡型肿块。2例病例术后分别行安罗替尼和铂类等多药联合化疗，肿瘤未控制，患者分别于术后11和8个月死亡。镜下观察肿瘤细胞呈弥漫片状、巢状、索状分布，可见假腺样结构。肿瘤细胞呈上皮样，形态较为一致，灶状区域见核偏位的横纹肌样细胞，小灶可见多核瘤巨细胞，间质较少，均可见坏死。免疫表型：2例肿瘤细胞SMARCA4编码蛋白BRG1均失表达，而SMARCB1编码蛋白INI1均阳性表达；波形蛋白弥漫强阳性；上皮标志物广谱细胞角蛋白（CKpan），胃肠道间质瘤标志物CD117和DOG1，肌源性标志物结蛋白和myogenin，黑色素瘤标志物S-100蛋白、SOX10和HMB45，淋巴造血系统标志物白细胞共同抗原和CD20均阴性。结论:胃SWI/SNF复合体缺失的未分化癌/横纹肌样癌是一类罕见的高度恶性肿瘤，预后差。SWI/SNF复合体的亚单位蛋白表达水平的检测对于该肿瘤的诊断有重要的应用价值。

abstractsObjective:To investigate the clinicopathological features, immunohistochemical characteristics, differential diagnosis and prognosis of gastric SWI/SNF-complex deficient undifferentiated/rhabdoid carcinomas.Methods:Two cases of gastric SWI/SNF-complex deficient undifferentiated/rhabdoid carcinoma were collected at Fudan University Shanghai Cancer Center, Shanghai, China from 2017 to 2018. The clinicopathological characteristics were analyzed. Hematoxylin and eosin, and immunohistochemical stains were performed, and the relevant literatures were reviewed.Results:The two patients were both male, aged 60 and 74 years, respectively. Their symptoms were both abdominal pain. The tumor arose in the esophagogastric junction in case 1, and the cardia to the fundus and the posterior wall of the upper part of gastric body in case 2. Both tumors were present as an ulcerative mass. The patients died of tumor 11 months and 8 months after surgery, respectively. Histologically, the tumor cells arranged in sheets, nests, cords or trabecular patterns, and pseudoavleolar structure. The tumor cells were epithelioid with uniform morphology, while the tumors showed scant stroma and massive necrosis. Variable rhabdoid cells and multinucleated giant cells were seen in both cases. SMARCA4 encoding protein BRG1 was undetectable in both tumors, while SMARCB1 encoding protein INI1 was detected. The tumor cells were diffusely positive for vimentin and negative for epithelial marker (CKpan), gastrointestinal stromal tumor markers (CD117 and DOG1), myogenic markers (desmin and myogenin), melanoma markers (S-100 protein, SOX10 and HMB45), and lymphohematopoietic markers (LCA and CD20).Conclusions:Gastric SWI/SNF-complex deficient undifferentiated/rhabdoid carcinoma is a rare and highly aggressive tumor with poor prognosis. The detection of subunits protein expression of SWI/SNF complex is important for diagnosis of the tumor.