CD99 and alveolar rhabdomyosarcoma: GIST is positive for CD34 and CD117, alveolar rhabdomyosarcoma is positive for desmin and MyoD1, and is associated with a t(2;13)(q35;q14) chromosome translocation and synovial sarcoma often expresses the epithelial membrane antigens, CK7, CK19, and CD99.