Chronic myelogenous leukemia: a concise update.

HRONIC MYELOGENOUS leukemia (CML) is a C clonal myeloproliferative disorder of the primitive hematopoietic stem cell.’-3 It involves the myeloid, erythroid, megakaryocytic, B-, and sometimes T-lymphoid elements, but not the marrow fibrobla~ts.~,~ CML is characterized by (1) the heterogeneity of the disease among patients, (2) a biphasic or triphasic course, and (3) the presence of a chromosomal marker, the Philadelphia chromosome (Ph), in the leukemic Proliferation is a shared feature of CML and other myeloproliferative disorders such as essential thrombocytosis, polycythemia vera, and myeloid metaplasia/myelofibrosis. Although these entities are usually distinct, overlap in presentation is occasionally observed, resulting in diagnostic confusion. Thus, it is important to confirm the diagnosis of CML by cytogenetic (Ph chromosome) or molecular studies, because the natural history and treatment of the myeloproliferative disorders are different.