Department of Gastroenterology, Seirei Hamamatsu General Hospital, Hamamatsu, Japan.
Pathol Res Pract. 2013 Nov;209(11):745-50. doi: 10.1016/j.prp.2013.06.018. Epub 2013 Jul 8.
Synovial sarcoma (SS) is a mesenchymal spindle cell tumor which displays variable epithelial differentiation. It commonly arises around the major joints or tendon sheaths in young adults, but is not commonly seen in the stomach. We experienced a case of primary gastric SS. The patient is a 22-year-old male, who presented with epigastric pain. Upper endoscopy showed an ulcer of 25 mm in diameter with marginal elevation on the posterior mid-gastric body. Biopsy of the ulcer base showed monotonous proliferation of small spindle-shaped cells on HE-stain. On immunohistochemical staining, these cells were positively stained with vimentin, cytokeratin, epithelial membrane antigen, and CD99, but were negative for KIT, CD34, desmin, and S-100 protein. These findings were compatible with SS of monophasic type. Diagnosis of primary gastric SS was made because there were no other primary lesions, nor metastatic lesions. The wedge resection was performed. Reverse transcriptase polymerase chain reaction (RT-PCR), using the RNA from frozen neoplastic tissue of the resected specimen, detected a fusion gene called SYT-SSX1, specific for SS. Though SS arising in the stomach is rare, it should be considered in the differential diagnosis of KIT-negative gastric spindle cell tumor.
滑膜肉瘤（SS）是一种具有可变上皮分化的间叶性梭形细胞肿瘤。它通常发生在年轻成人的大关节或腱鞘周围，但在胃中并不常见。我们遇到了一个原发性胃 SS 的病例。患者为 22 岁男性，表现为上腹痛。上消化道内镜显示胃体中后侧壁直径 25mm 的溃疡，边缘隆起。溃疡基底的活检显示 HE 染色中小梭形细胞的单调增殖。免疫组织化学染色显示，这些细胞阳性表达波形蛋白、细胞角蛋白、上皮膜抗原和 CD99，但阴性表达 KIT、CD34、结蛋白和 S-100 蛋白。这些发现与单相型 SS 相符。由于没有其他原发性病变或转移性病变，诊断为原发性胃 SS。进行楔形切除术。使用从切除标本的冷冻肿瘤组织提取的 RNA 进行逆转录聚合酶链反应（RT-PCR），检测到一种称为 SYT-SSX1 的融合基因，这是 SS 的特异性标志。尽管胃 SS 较为罕见，但在诊断 KIT 阴性的胃梭形细胞肿瘤时应考虑到它。
