Possible Recurrence of Synovial Sarcoma Involving the Shoulder of a 57-Year-Old Female: A Rare Case Report from Iran

Abstract

Introduction: Synovial sarcoma (SS) is an uncommon malignant soft-tissue tumor that typically presents as a slow-growing mass in the extremities, adjacent to joint capsules. SS has three subtypes: monophasic, biphasic, and poorly differentiated. Standard treatment primarily involves complete surgical resection of the tumor mass, with or without adjuvant or neoadjuvant therapies. Case Presentation: We report a possible recurrence of SS in the left shoulder of a 57-year-old woman 2 decades after the initial diagnosis. She had previously undergone surgical resection of SS in the right axilla. Years later, a tumor developed in the contralateral shoulder, with regional lymph-node involvement. Magnetic resonance imaging and computed tomography revealed a large infiltrative mass with internal vasculature and bone involvement in the left shoulder. Pathological analysis supported the diagnosis of monophasic SS based on cellular morphology and the expression profile of markers including CD99, epithelial membrane antigen, and Bcl-2. The patient declined surgical resection and received 8 cycles of chemotherapy with doxorubicin and ifosfamide. She died of cardiorespiratory arrest 18 months after the diagnosis of the recurrent tumor. Conclusions: SS is characterized by a high rate of metastasis and may recur more than 5 years after initial diagnosis. This case underscores the need for long-term surveillance and careful evaluation of new soft-tissue masses in patients with a history of SS.