Unusual cytogenetics in a case of acute lymphoblastic leukemia

The cytogenetics in the study of a patient with acute lymphoblastic leukemia are presented. Initially, a large proportion of both unstimulated and phytohemagglutinin (PHA)-stimulated blood mitoses showed an abnormal karyotype with a 7;12 translocation and a trisomy 19. At the time of relapse, a PHA-stimulated culture showed the clonal abnormality as well as dicentric chromosomes in normal cells, the latter possibly resulting from treatment.