A rare case and unusual localization of a poorly differentiated giant synovial sarcoma of the ankle: Case report and literature review

INTRODUCTION: Synovial sarcoma is a rare and aggressive soft tissue tumor that affects the para-articular regions of the large joints. It originates from mesenchymal cells with synovial differentiation. Its management remains surgical with wide excision. CASE PRESENTATION: We report a case of synovial sarcoma with rare localization that occurred in a 37-year-old man on the inner side of the right ankle, and we recall the clinical, radiological, and histological signs that allowed us to suggest the diagnosis as well as multidisciplinary management. DISCUSSION: Synovial sarcoma is a highly aggressive soft tissue tumor with a high risk of spreading. It is a deceptive tumor in some clinical and morphological aspects that may indicate benignity. Although non-specific, MRI is critical for guiding diagnosis, identifying prognostic criteria, and ensuring post-treatment follow-up. CONCLUSION: This rare case underlines the importance of evoking a synovial sarcoma in front of a mass of soft parts of the benign aspect of the ankle, as well as adapting the treatment in order to prevent possible metastases, especially in the lungs.