Ewing's sarcoma and peripheral primitive neuroectodermal tumor.

Disease-free survival for patients with small sarcomas of bone has been impressively improved with the use of intensive combination chemotherapy and safe local control with surgery or radiation. The ability of monoclonal antibodies to recognize different antigens has allowed new insights into the histogenesis and has distinguished a neural variant now referred to as malignant peripheral neuroectodermal tumor. Both entities share the translocation t(11;22) (q24;q12) as a constant phenomenon. The breakpoint region has now been cloned, allowing for molecular identification and detection of tumor cells and opening a new era of diagnostic and staging possibilities. Patients with disseminated disease, either at diagnosis or in relapse, have benefitted from megatherapy regimens followed by bone marrow or peripheral stem cell rescue. However, this approach is still under investigation and remains to be standardized.