Identical chromosome 1p breakpoint abnormality in both the tumor and the constitutional karyotype of a patient with neuroblastoma.

A 4-year-old boy with a stage III abdominal neuroblastoma was studied. Direct chromosome preparation revealed a t(1;?)(p36;?) in three tumor metaphases (one with a chromosome number of 64). After partial resection of the tumor and further tumor shrinkage by intensive combination chemotherapy, the residual tumor mass was removed by a "second-look" operation, and the patient received postoperative radiotherapy to the tumor area. Chromosome analysis from the peripheral blood taken at that time showed tetraploidy in 14% and hypodiploidy in 66% of 50 available metaphases. Structural abnormalities, mainly involving the distal short arm of chromosome 1, could be identified in seven metaphases. A t(1;?)(p36;?) in a diploid blood cell looked identical to the translocation found in the hyperdiploid tumor metaphase. A del(1)(p36) was also found in a blood cell. It is suggested that an association exists between a chromosome fragility at 1p36, in this case postoperatively induced in vivo by chemoradiotherapy, and the development of neuroblastoma.