The significance of cytogenetic findings of erythroid colonies derived from a Ph+ ALL patient: fundamental differences between Ph+ ALL and blastic phase CML.

Cytogenetic analysis was performed on colonies from erythroid burst-forming units (BFU-E) derived from bone marrow (BM) cells of a Ph-positive acute lymphocytic leukemia (Ph+ ALL) patient. A normal diploid karyotype was revealed in all 15 metaphases that could be analyzed in the erythroid colonies. Previous cytogenetic analyses of erythroid colonies obtained from BM cells of patients with Ph+ chronic myelogenous leukemia (CML) revealed that Ph-positive karyotypes were predominant in all 11 cases. Two of them were also examined in blastic phase (BP) and showed 100% Ph+ cells in BFU-E-derived colonies. The present findings suggest that the leukemic process of Ph+ ALL does not involve the erythroid series, which is in contrast to the involvement in CML. This is considered to be a fundamental difference between Ph+ ALL and the blastic phase of CML (BP CML). Clinically, cytogenetic analysis of erythroid colonies from BM cells may constitute a valuable approach for the differential diagnosis between Ph+ ALL and the BP of Ph+ CML.