Macroscopic vascular invasion in synovial sarcoma evident on MRI

We present a case of recurrent synovial sarcoma in the soft tissues of the calf, where MR imaging not only confirmed the diagnosis of tumour recurrence, but also demonstrated direct venous invasion and tumour thrombus within the popliteal vein and its tributaries. Venous invasion has particular relevance to synovial sarcoma prognostication and should be actively sought on MR imaging. To our knowledge this is the first reported case in the English literature of histologically proven macroscopic popliteal vein invasion from a synovial sarcoma demonstrated on MR imaging.