3 | DISCUSSION
Synovial sarcoma is generally considered a high-grade aggressive sarcoma, with a poorer prognosis in adults than in children[4]. Prognostic factors also include tumor size, use of radiotherapy and/or chemotherapy, histological subtype, and surgical margin status, among which tumor size >5 cm at the time of treatment is consistently associated with poor prognosis[5]. In addition, synovial sarcoma has a high metastatic potential, and its metastatic rate can reach more than 50%[6]. The most common metastatic site is the lung[7]. Other metastases include lymph, bone, and liver, but patients with gastrointestinal metastases are rare. At present, there were only a few dozen cases of metastatic synovial sarcoma in the gastrointestinal tract had been reported in the literature[8].
In addition to intestinal metastases, the patient was characterized by a particularly rapid progression. It was only 20 days from the time of admission to the patient’s death. Although this was related to the delay in the patient’s visit to the hospital, the progression of metastases in the patient after admission was very rare. The interval between two CT scans was only 4 days, but the liver and intestinal metastases progressed significantly. Due to the rapid progression, patients lost opportunities for surgery and chemotherapy.
Synovial sarcoma has typical pathological and genomic features including immunohistochemical features and a t(X;18)(p11.2;q11.2) chromosomal translocation in which the SS18(SYT) gene (18q11) is associated with SSX (including SSX1) , SSX2, SSX4, Xp11) gene fusion, resulting in the generation of the SS18-SSX fusion gene, which occurs in most patients[9]. Some RNAs may act in concert with fusion genes to cause rapid tumor progression, but the exact map has not yet been determined[10]. Gene sequencing of this patient showed a significantly higher number of homozygous mutations compared to conventional synovial sarcoma patients. The pathological mechanisms involved in these mutated genes are all involved in immune system exhaustion and tumor transcriptional dysregulation, which may be the reason for the rapid tumor progression in this patient. Humoral and cellular immunity, including the functional expression of T17 and Th cells, may have certain relevance to the progression and prognosis of synovial sarcoma[11]. Of course, this remains to be verified by further research.