Synovial sarcoma with squamous metaplasia

We report on a biphasic synovial sarcoma showing slight squamous cell differentiation of their epithelioid component under the light microscope. The electron microscopical examination revealed numerous tonofilaments arranged in dense bundles, which could be characterized as tonofibrils with keratohyalin granules in the same cells. The presence of such structures indicates the possibility of squamous metaplasia in biphasic synovial sarcoma.