Evolution of tumor cytogenetic aberrations and N-myc oncogene amplification in a case of disseminated neuroblastoma.

Chromosome analyses including in situ hybridization with the protooncogene N-myc were carried out at diagnosis and several times at relapse in the bone marrow cells of a girl with disseminated neuroblastoma (stage IV) at ages 9, 23, 24, and 26 months, respectively. The tumor karyotype was pseudodiploid exhibiting partial monosomy for the short arm of chromosome #1, an aberration of the short arm of chromosome #2, and double minutes at diagnosis. Further structural aberrations of chromosomes #4, #6, and #17, and homogeneously staining regions could be demonstrated at relapse. In particular, the following structural aberrations were encountered: t(1;?)(p22;?),t(2;?)(p24;?), t(4;6)(q31;q25), and a der(17q). All tumor metaphases without homogeneously staining regions contained double minutes. N-myc, normally positioned within bands 2p23-24, was found to be amplified in a homogeneously staining region on the short arm of chromosome #15 by in situ hybridization. It is speculated that the translocation t(2;?)(p24;?) might be related to N-myc oncogene activation and subsequent amplification.