Abstract
A 36-year-old female with a remote history of spontaneous pneumothorax treated with talc pleurodesis presented with a large anterior mediastinal synovial sarcoma. The mass developed within a residual asymptomatic mediastinal space during a 2-year period. The patient underwent complete surgical resection and adjuvant chemoradiotherapy, which provide the best chance for survival. Although the cause of these tumors is unclear, this report may further delineate the natural history of this rare pathologic process.