Isodicentric Philadelphia chromosome in accelerated phase of chronic myeloid leukemia.

We describe a case of chronic myeloid leukemia (CML) associated with the finding of an isodicentric Philadelphia chromosome [idic(Ph)] during the accelerated phase of the disease. Chromosome study was carried out on bone marrow aspirate cells, obtained and cultured 5 months after the clinical diagnosis. The presence of an isodicentric Philadelphia chromosome was found in 90% of the analyzed metaphases; among the remaining observed metaphases, 6% showed two idic(Ph) chromosomes, 2% a t(9;22), and 2% a normal karyotype. The patient died 7 months after the clinical diagnosis, and 2 months after our chromosome study. The observation of idic(Ph) during CML has seldom been reported and the few cases studied have been inconsistently correlated with the course of the disease. In the present case, the finding of an idic(Ph) and the short patient survival from the time of clinical diagnosis may suggest the observed chromosome aberration as a factor associated with a poor prognosis.