A Case of Primary Gastric Synovial Sarcoma

Abstract

A 68-year-old woman had a screening for stomach cancer and was found having a gastric submucosal tumor with a central depression in the upper body in May 2018. She was referred to our hospital for further examination and was diagnosed with synovial sarcoma by an endoscopic biopsy. PET-CT examination demonstrated an abnormally high uptake of FDG in the stomach. No other abnormal uptake indicating metastasis, was observed. Therefore, we diagnosed her case as primary gastric synovial sarcoma and decided to conduct laparoscopic partial gastrectomy. We performed intraoperative endoscopy to identify the location of the tumor, followed by partial gastrectomy with a 2-cm margin of excision and nearby lymph node sampling. The resected specimen showed a tumor with the major axis of 9 mm, ill defined, and mainly positioned in the submucosa, in which bundled growth of spindle-shaped tumor cells was observed. Tumor cells were positive for cytokeratin, EMA, and bcl-2 by immunohistochemical examination. And we observed split signal by the FISH method using the SS18 probe. No other lesions were found, and the patient was diagnosed with primary gastric synovial sarcoma. No local or distant recurrence has occurred as of two years and 6 months after the operation. Primary gastric synovial sarcoma is a very uncommon neoplasia.