Prognostic implication of desmoplastic stroma in synovial sarcoma: A histological review

Synovial sarcoma (SS) is a malignant soft tissue neoplasm harboring SS18-SSX fusion gene and is histologically characterized by spindle cells and epithelial components. Some investigations have demonstrated that desmoplastic reaction (DR) is an independent prognostic factor of cancers. However, it remains unknown whether DR is of predictive value for the prognosis of synovial sarcoma patients. Here, we reviewed the clinical and histological findings of 88 patients with SS. We defined DR as hyalinized collagenous structures and classified the degree of DR as follows: none, mild, moderate, and severe. Overall, 23 SS cases (24%) showed moderate or severe DR histologically. Statistically, the cases with moderate or severe degree of DR showed poorer prognosis than those with no or mild DR (local recurrence: P = 0.0059, distant metastasis: P = 0.0002, tumor death: P = 0.0382). The findings of the study suggest that the DR of synovial sarcoma could be an important prognostic factor.