Cytogenetic studies in basophilic chronic myelocytic leukemia.

Basophilia is found in association with many diseases and is commonly seen in patients with chronic myelocytic leukemia (CML). Substantial basophilia development during the course of CML has been considered to be a poor prognostic sign. Prominent basophilia occasionally has been seen in patients at the time of the original diagnosis. These cases have been classified as "basophilic leukemia." A patient with a basophil count of 24,080/cu mm and myeloid immaturity in his peripheral blood had typical Ph1 chromosome in his bone marrow. G-banding studies showed typical 22q-;t(9q+;22q-) of CML. Since seven of the nine basophilic leukemias so far studied cytogenetically have Ph1 chromosomes and since Ph1 chromosomes are absent in the majority of eosinophilic leukemias, we believe it more appropriate to call basophilic leukemia basophilic CML.