Double 9;22 translocation with hyperdiploidy appearing in blastic transformation of chronic granulocytic leukemia

Chromosome studies in a 26-year-old female with Ph1-positive chronic granulocytic leukemia showed the development of both hyperdiploid and tetraploid cell lines in the blastic transformation phase. An additional 9;22 translocation and additional chromosomes No. 8, 11, 13 and 22 were found in the hyperdiploid cell line. This unusual finding suggests that the hyperdiploidy may have developed from misdivisions in the tetraploid cell line rather than by the more accepted mechanism of nondisjunction or selective endoreduplication from a diploid cell.