Clonal karyotypic evolution in an embryonal rhabdomyosarcoma with trisomy 8 as the primary chromosomal abnormality.

An embryonal rhabdomyosarcoma was analyzed cytogenetically. In primary cultures fed a serum-containing medium, 11 clones with karyotypic abnormalities were found. One had trisomy 8 only. The other 10 clones had trisomy 8 as well as additional evolutionary changes that included trisomy for part or all of chromosome 2, isochromosomes for the short and long arms of chromosome 11, isochromosomes for the long arm of chromosome 8, and extra copies of chromosome 8, some of which had an interstitial deletion in 8q. In those primary cultures that had grown in a chemically defined, serum-free medium and in all passaged cultures, trisomy 8 was the only aberration. Our findings and a survey of published information point to gain of one chromosome 8 as a frequent primary karyotypic abnormality in embryonal rhabdomyosarcomas. Trisomy for part or all of chromosomes 2 and 11 and additional gains of chromosome 8 material seem to be common secondary changes.