Primary synovial sarcoma of the duodenal bulb is a rare mesenchymal tumor with special morphological features. It usually originates from the major joints or tendon sheaths of the extremities and mostly seen in young population, but rarely found in gastrointestinal tract. In this manuscript, we reported the first case of synovial sarcoma arising between the intestinal wall of the duodenal bulb with a concomitant SYT/SSX type of the t(X;18) translocation. A 49-year-old male presented to our hospital with a 2-month history of upper abdominal pain along with a 4-day amply jaundice. Tumor marker testing showed only a slight increase of carbohydrate antigen 19-9 (CA19-9). A computed tomography scan of his abdomen showed that indeterminate tissue occupied the duodenal bulb wall, compressed the surrounding tissues, and measured roughly 5.0 cm × 7.7 cm × 8.7 cm. Since the sarcoma grows between the intestinal wall, which cannot be detected by endoscopy, an initial diagnosis of duodenal wall stromal tumor was made at that time. Postoperative Immunohistochemistry results showed that the tumor was positive for the expression of transducin-like enhancer of split 1, B-cell lymphoma 2, and Vimentin. These pathological findings were indicative of the diagnosis of synovial sarcoma, but still did not provide sufficient diagnostic evidence. Finally we confirmed the diagnosis by using fluorescence in situ hybridization (FISH) with detection of the t(X;18) (SYT-SSX) translocation. No such lesions were found on preoperative examination, so a diagnosis of primary duodenal synovial sarcoma was made. After literature review, we found four reports of duodenal synovial sarcomas, all of which could be detected endoscopically, but there were no results of long-term follow-up. This case is the first reported case of synovial sarcoma arising between the intestinal walls of the duodenal bulb treated twice with ifosfamide and followed up for 13 months without recurrence.
Keywords: Synovial sarcoma; duodenal bulb; fluorescence in situ hybridization; immunohistochemistry.
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