Abstract
A case of intravascular biphasic synovial sarcoma arising from the wall of the left femoral vein in a 34 year old woman is described. This is the third case of an intravascular synovial sarcoma known to be reported in the medical literature. The two previous cases arose from the left femoral vein and inferior vena cava in women of 34 and 31 years old, respectively. A characteristic clinical pattern appears to be emerging--that is, location in large veins of the lower extremity and trunk in young adult females. Synovial sarcoma must be considered in the differential diagnosis of intravascular "tumours".