NTRK1 and desmoplastic small round cell tumor: This suboptimal specificity of IHC for fusion identification, with the antibody marking expression of wild-type Trk protein as emerged in this study, had already been noted in previous work experiences for other cancers with variable myogenic differentiation, including uterine leiomyosarcoma (22), rhabdomyosarcoma (23), and desmoplastic small round cell tumour (3).