CTAG1B and dermatofibrosarcoma protuberans: The robust expression of NY‐ESO‐1 in synovial sarcoma has also been proposed as a marker to differentiate synovial sarcoma from other spindle cell neoplasms, in which NY‐ESO‐1 expression is rare such as leiomyosarcoma, cellular schwannoma and dermatofibrosarcoma protuberans.32, 33