Changchien Yi-Che, Katalin Uhrin, Fillinger János, Fónyad László, Papp Gergő, Salamon Ferenc, Sápi Zoltán
1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest 1085, Hungary.
Case Rep Pathol. 2012;2012:786083. doi: 10.1155/2012/786083. Epub 2012 Aug 27.
The primary and metastatic gastrointestinal synovial sarcoma is rare with a wide differential diagnosis. It usually expresses cytokeratins EMA, BCL2 with an occasional CD99, and S100 positivity but not desmin. We present a case of metastatic synovial sarcoma with unusual immunophenotype causing diagnostic challenges. The tumor cells showed focal cytokeratin, EMA, and, unexpectedly, desmin positivity. Additional intranuclear TLE-1 positivity and negativity for CD34 and DOG-1 were also identified. A diagnosis of monophasic synovial sarcoma was confirmed by using FISH break-apart probe. RT-PCR revealed the SYT-SSX1 fusion gene. Intra-abdominal synovial sarcoma, either primary or metastatic, with unusual desmin positivity raises the diagnostic challenge, since a wide range of differential diagnoses could show a similar immunophenotype (leiomyosarcoma, desmoid tumor, myofibroblastic tumor, and rarely GIST etc.). Typical morphology and focal cytokeratin/EMA positivity should alert to this tumor, and FISH and RT-PCR remain the gold standard for the confirmation.
原发性和转移性胃肠道滑膜肉瘤罕见，鉴别诊断范围广。它通常表达细胞角蛋白、上皮膜抗原（EMA）、BCL2，偶尔CD99呈阳性，S100也呈阳性，但结蛋白阴性。我们报告一例具有不寻常免疫表型的转移性滑膜肉瘤病例，该病例给诊断带来了挑战。肿瘤细胞显示局灶性细胞角蛋白、EMA阳性，出乎意料的是，结蛋白也呈阳性。还发现肿瘤细胞额外呈核内TLE-1阳性，CD34和DOG-1阴性。通过荧光原位杂交（FISH）断裂分离探针证实为单相滑膜肉瘤。逆转录聚合酶链反应（RT-PCR）检测到SYT-SSX1融合基因。腹内滑膜肉瘤，无论是原发性还是转移性，出现不寻常的结蛋白阳性都会带来诊断挑战，因为多种鉴别诊断可能表现出相似的免疫表型（平滑肌肉瘤、硬纤维瘤、肌成纤维细胞瘤，罕见的胃肠道间质瘤等）。典型的形态学表现以及局灶性细胞角蛋白/EMA阳性应提示该肿瘤的可能，而FISH和RT-PCR仍然是确诊的金标准。
