Rare presentation of synovial sarcoma in the foot: A case study

Synovial sarcoma is a rare, high-grade soft tissue malignancy that most commonly affects the extremities of adolescents and young adults, with a predilection for the foot and ankle. We present the case of a 47-year-old male with a 12-month history of progressive left foot dorsal swelling and pain. Initial imaging suggested a soft tissue hemangioma; however, surgical excision and subsequent histopathologic and molecular analysis revealed a monophasic synovial sarcoma with SS18-SSX gene fusion. The patient underwent wide re-excision of the tumor bed in coordination with orthopedic oncology. Final pathology confirmed negative margins, and no metastatic disease was identified on PET or chest CT. Given the complete resection and absence of residual disease, adjuvant radiation therapy was deferred. The patient remains disease-free on surveillance imaging at follow-up. This case highlights the diagnostic challenges of synovial sarcoma in the foot and ankle and emphasizes the importance of early biopsy, multidisciplinary coordination, and adherence to oncologic principles for optimal outcomes. Malignancy should remain a consideration in the differential diagnosis of persistent soft tissue masses.