Blast crisis of Ph-positive chronic myeloid leukemia with isochromosome 17q: Report of 12 cases and review of the literature

Isochromosome 17q [i(17q)] is frequently observed in the blast crisis (BC) of chronic myelogenous leukemia (CML). It has been suggested that this chro mosome abnormality is associated with special hematological characteristics of the BC, but the information on this subject is scarce. The clinical, he matological and cytogenetic features of patients with i(17q) were analyzed in a series of 121 patients with BC of Ph-positive CML. Twelve patients (10 %) displayed an i(17q), representing the third commonest cytogenetic abnorm ality, after trisomy 8 and Ph chromosome duplication. In seven of the 12 pa tients the BC was preceded by an accelerated phase, and 10 had more than 10 % blood basophils at BC diagnosis. The blast cells had a myeloid phenotype in the 12 patients. Five patients exhibited cytogenetic abnormalities in ad dition to i(17q), with trisomy 8 and duplication of the Ph chromosome being the alterations most frequently observed. Median survival of patients with i(17q) was 22 weeks, which was not significantly different from the surviv al of patients with myeloid BC in the overall series. These results are sim ilar to the findings in 181 patients with i(17q) from 12 series of the lite rature, and confirm the special hematologic profile of BC of CML with this cytogenetic abnormality.