[Cytogenetics of bone sarcomas].

There has been much progress in the cytogenesis, and molecular biology of bone tumours such as Ewing sarcoma and osteosarcomas, greatly improving diagnostic possibilities and prognosis. Ewing's sarcoma is an indifferentiated sarcoma with round cells which usually occurs in children or adolescents. Ewing's sarcoma corresponds to 6% of all bone tumours. Histologically Ewing's sarcoma belongs to a group of small round cell tumours including neuroblastoma, embryon and alveolar rhabdomyosarcoma and non-Hodgkin's lymphoma. Differential diagnosis is difficult. Cytogenetic examinations can now differentiate Ewing's sarcoma from other small round cell tumours. There is a specific 11:12 translocation (q24; q12) which can be used as a marker.