Monophasic synovial sarcoma of the thigh in a 60-year-old patient: A rare case report and literature review

Synovial sarcoma typically affects adolescents and young adults, and presentation in patients over 60 years is distinctly uncommon. We report a case of monophasic synovial sarcoma of the thigh in a 60-year-old woman, highlighting the diagnostic challenges associated with atypical age and nonspecific early clinical findings. MRI demonstrated a multilobulated soft-tissue mass with heterogeneous T2 signal, internal septations, and postcontrast enhancement consistent with high-grade sarcoma. Histopathology revealed a spindle-cell neoplasm with diffuse TLE1 and BCL2 positivity, and fluorescence in situ hybridization confirmed SS18-SSX fusion. The patient underwent wide surgical excision with negative margins and recovered uneventfully. This case emphasizes the importance of maintaining synovial sarcoma in the differential diagnosis of deep thigh masses in older adults, where imaging and molecular confirmation are essential to avoid misdiagnosis and treatment delay.