Kohashi Kenichi, Oda Yoshinao, Yamamoto Hidetaka, Tamiya Sadafumi, Oshiro Yumi, Izumi Teiyu, Taguchi Tomoaki, Tsuneyoshi Masazumi
Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, Japan.
Am J Surg Pathol. 2008 Aug;32(8):1168-74. doi: 10.1097/PAS.0b013e318161781a.
Several previous studies have demonstrated the lack of SMARCB1/INI1 protein expression in only the malignant rhabdoid tumor (MRT). Several sarcoma groups are associated with a tumor-specific translocation involving EWS. Moreover, the EWS and SMARCB1/INI1 genes are located on the same 22q chromosome. We analyzed the status of SMARCB1/INI1 protein expression in 93 cases of sarcomas associated with chromosomal translocation involving EWS, comprising 52 Ewing's sarcoma/primitive neuroectodermal tumors, 24 extraskeletal myxoid chondrosarcomas (EMCS), 14 clear cell sarcomas of soft tissue, 2 desmoplastic small round cell tumors, and 1 myxoid/round cell liposarcoma. In addition, we analyzed the detailed SMARCB1/INI1 gene alteration in cases, which lacked its protein expression. Consequently, 4 EMCS showed no SMARCB1/INI1 expression, and 2 of these 4 cases revealed homozygous deletion and frameshift mutation of the SMARCB1/INI1 gene, respectively. These cases showed histologic findings compatible with EMCS, according to the most recent WHO classification, but no major fusion gene transcripts were detected. Moreover, 3 out of 4 SMARCB1/INI1 negative variant EMCS disclosed rhabdoid features. Therefore, the lack of SMARCB1/INI1 protein expression may be associated with rhabdoid features. The immunohistochemical result of the SMARCB1/INI expression is not an absolute diagnostic criteria for MRT and careful histologic evaluation is required to make a precise diagnosis of MRT.
先前的多项研究表明，仅在恶性横纹肌样瘤（MRT）中缺乏SMARCB1/INI1蛋白表达。几个肉瘤组与涉及EWS的肿瘤特异性易位相关。此外，EWS和SMARCB1/INI1基因位于同一条22号染色体上。我们分析了93例与涉及EWS的染色体易位相关的肉瘤中SMARCB1/INI1蛋白表达情况，其中包括52例尤因肉瘤/原始神经外胚层肿瘤、24例骨外黏液样软骨肉瘤（EMCS）、14例软组织透明细胞肉瘤、2例促结缔组织增生性小圆细胞肿瘤和1例黏液样/圆形细胞脂肪肉瘤。此外，我们分析了缺乏该蛋白表达的病例中SMARCB1/INI1基因的详细改变情况。结果显示，4例EMCS无SMARCB1/INI1表达，其中2例分别显示SMARCB1/INI1基因的纯合缺失和移码突变。根据最新的世界卫生组织分类，这些病例显示出与EMCS相符的组织学表现，但未检测到主要的融合基因转录本。此外，4例SMARCB1/INI1阴性的变异型EMCS中有3例表现出横纹肌样特征。因此，SMARCB1/INI1蛋白表达的缺失可能与横纹肌样特征有关。SMARCB1/INI表达的免疫组化结果并非MRT的绝对诊断标准，需要仔细的组织学评估才能对MRT做出准确诊断。
