Primary biphasic synovial sarcoma of the orbit.

Synovial sarcoma is one of the most common soft tissue malignancies of adolescents and young adults. Despite its name, it is no longer thought to be histogenetically derived from the synovium. What seems to be the first case of synovial sarcoma to arise in the orbit presented in a 21 year old woman as a slowly enlarging subconjunctival mass. Although this tumour was typically biphasic, the monophasic spindle cell variant arising at this site could easily be confused with less aggressive orbital connective tissue neoplasms.