Femoral Vein Intravascular Synovial Sarcoma Mimicking Primary Deep Vein Thrombosis-A Rare Cause of Deep Vein Thrombosis

Synovial sarcomas are rare malignant mesenchymal soft tissue tumors. We presented the case of a 53-year-old woman patient presenting with acute deep vein thrombosis, later diagnosed as a deep synovial sarcoma of the femoral vein wall. The tumor was identified through cross-sectional magnetic resonance angiography and computed tomography, followed by ultrasound-guided core biopsy. The case report emphasized the importance of considering the possibility of an intravascular neoplasm mimicking thrombus, particularly if calcifications, vein expansion with intravascular cystic spaces, fluid-fluid levels, and septations within a thrombosed vein are seen in imaging.