The eleventh cytogenetically analyzed Askin's tumour, diagnosed in a 
two-year-old girl, is reported. Chromosomal analysis revealed a pseudodiploid 
karyotype of tumour cells with translocations of t(11;22)(q24;q12) and 
der(4)t(2;4)(q24;q35). The observed t(11;22)(q24;q12) is not only a unique 
characteristic of all cytogenetically analyzed Askin's tumours but it also 
occurs in 92-100% of peripheral neuroepithelioma and of Ewing's sarcoma, 
irrespective of its osseous or extraosseous localization. This genetical 
similarity further supports a nosological concept according to which Askin's 
tumour, Ewing's sarcoma and peripheral neuroepithelioma represent phenotypic 
variations of the same tumour, namely the peripheral primitive neuroectodermal 
tumour.