Primary Intraosseous Synovial Sarcoma: Experience from a Tertiary Cancer Center.

Introduction: Primary intraosseous synovial sarcoma (PISS) is a rare cancer of the bone, with few reported cases across literature. Data from our institute reveals seven indigenous cases. This study aims to evaluate these PISS diagnoses, and to further investigate any histopathological findings and prognostic factors associated with patient survival. Materials and Methods: Data from patients diagnosed with PISS at the institute were obtained from January 1995 to December 2016, in the form of a retrospective study. Patient demographics, pathology locations, histological findings, surgical margins, and treatment modalities were audited as variables that can impact patient survival. Results: This research identified seven cases which fulfilled the diagnostic criteria and were subsequently classified as PISS of the bone. There were five men and two women among the cases, with ages ranging from 16 to 46 years, with a mean of 29.6 years. The study found that the lower limb was the most affected site in PISS, followed by the pelvis. Limb salvage was performed in six patients and one patient underwent amputation. Of these patients, six received adjuvant chemotherapy and four received adjuvant radiation as per institution guidelines. The study found that the 5-year disease-free and overall survival rate was 80 and 61%, respectively. Conclusion: PISS is a rare malignancy with limited cases in literature, and hence, there is no evidence for a standardized management protocol. The survival rates were similar between soft tissue and intraosseous synovial sarcoma among the case series.