腹膜后滑膜肉瘤6例临床病理及分子病理学分析

目的:探讨腹膜后滑膜肉瘤的临床病理特征、免疫表型及分子遗传学改变。方法:收集北京大学国际医院病理科2014年12月至2021年07月期间手术切除腹膜后标本病理诊断为滑膜肉瘤6例，进行光镜观察、免疫表型及分子病理学分析，并复习相关文献。结果:男性2例，女性4例，年龄12~56岁（平均年龄29岁，中位年龄26岁）；肿瘤大小8~20 cm，平均15.2 cm，界限较清，梭形细胞型5例，双相型1例；CKpan、EMA、Bcl-2、CD99、TLE1、Vimentin、CD34、Calponin阳性比例分别为5/6、6/6、6/6、3/6、6/6、5/6、0/6、4/6，INI1呈特殊模式表达6/6，Ki-67高表达；FISH结果显示6例均有SS18-SSX基因融合；3例为SS18-SSX2基因融合，并有伴随基因突变。结论:腹膜后滑膜肉瘤是少见的发病部位，明确诊断常需结合组织病理学形态、免疫组织化学表达及分子遗传学特征进行综合分析。

Clinicopathological and molecular pathological analysis of 6 cases of retroperitoneal synovial sarcoma

Objective:To investigate the clinicopathological features,immunophenotype and molecular genetic changes of retroperitoneal synovial sarcoma.Methods:The retroperitoneal specimens from the department of pathology of Peking University International Hospital from December 2014 to July 2021 were collected,and 6 cases of synovial sarcoma were pathologically diagnosed.Light microscopic observation,immunophenotypic and molecular pathological analysis were performed,and the relevant literature was reviewed.Results:There were 2 males and 4 females,aged from 12 to 56 years old(mean age 29 years old,median age 26 years old).The tumor size was 8~20 cm,with an average of 15.2 cm.The boundary was clear.There were 5 cases of spindle cell type and 1 case of biphasic type.The positive rates of Ckpan,EMA,Bcl-2,CD99,TLE1,Vimentin,CD34 and Calponin were 5/6,6/6,6/6,3/6,6/6,5/6,0/6 and 4/6 respectively.INI1 was expressed in a special pattern 6/6.Ki-67 was highly expressed.FISH results showed that 6 cases had SS18-SSX gene fusion;Three cases were SS18-SSX2 gene fusion with concomitant gene mutation.Conclusion:Retroperitoneal synovial sarcoma is a rare site.The definite diagnosis often needs to be combined with histopathological morphology,immunohistochemical expression and molecular genetic characteristics.