Philadelphia chromosome-negative chronic myelogenous leukemia in a child with t(8;9)(p11 or 12;q34).

Approximately 78% of chronic myelogenous leukemia patients have the standard Ph' chromosome-negative defect as their only chromosomal abnormality. CML has been extensively studied due to the availability of tumor tissue and the frequency and consistency with which such abnormalities are noted. There have been few cases reported, however, of Ph' chromosome-negative CML with an abnormality involving rearrangement and breaks at the 9q34 band. We report here a unique case of the fourth Ph'-negative patient who demonstrates this break.