Contribution of cytogenetics to the diagnosis of Ewing's sarcoma and small round cell tumors]

The diagnosis of the so-called "small-round-cell tumours" in children and adolescents is a troublesome problem, particularly in specific forms of the disease or/and in undifferentiated cell proliferations. Under these circumstances the finding of a specific chromosomal abnormality in the tumour cells is invaluable, specially for the diagnosis of Ewing sarcoma and primitive neuroectodermal tumours as well as alveolar rhabdomyosarcoma. The use of cytogenetics, in combination with morphological and immunohistochemical studies to identify cell differentiation markers, is either the only positive diagnostic criterion, or a complementary factor in diagnosis.