The authors report on a case of radiation-induced malignant Triton tumor eg malignant schwannoma with rhabdomyoblastic differentiation). The tumor was situated in the brachial plexus of a patient who had received irradiation therapy 20 years previously for breast carcinoma. Pathological and immunohistological features have been described: coexpression of PS100, vimentin and desmin indicate a common neuroectodermic origin. A review of the literature has been presented in order to evaluate the diagnostic and prognostic characteristics of this unusual tumor and its relationship to neurofibromatosis.