Heterogeneous features of Ph-negative CML--possible existence of Ph-negative, bcr-rearrangement-negative CML.

We have examined eight patients with Ph-negative chronic myelocytic leukemia (CML). Two of the patients had the same molecular abnormalities as well as the same clinical and hematological features as those of Ph-positive CML. The other six patients showed no genomic rearrangement. This group was hematologically divided into four subgroups, namely chronic myelomonocytic leukemia, undifferentiated chronic myeloproliferative disorder, chronic neutrophilic leukemia and CML-like syndrome. This last subgroup resembled Ph-positive CML in many points except for rather moderate proliferation of granulocyte lineage, and it was difficult to clinically separate it from Ph-positive CML.