Classification of chronic myeloid leukemia (CML)

Clinical variants of CML:

1. Typical CML (Philadelphia chromosome present, BCR/ABL-positive [94%])

2. Atypical CML (Philadelphia chromosome absent, BCR/ABL-positive [4%])

3. Atypical BCR/ABL negative CML (Philadelphia chromosome absent, BCR/ABL-negative [2%])

Staging of CML

Chronic phase:

1. No significant symptoms

2. None of the features of accelerated phase or blastic phase

3. Sensitive to tyrosine kinase inhibitors (TKIs) (most newly diagnosed cases, see page 64)

4. Resistant to TKIs

Accelerated phase (any one or more of the following criteria):

1. WBC count difficult to control with conventional use of TKI or busulfan/hydroxyurea in terms of doses required

2. Rapid doubling of WBC count (≥5 days)

3. ≥10% blasts in blood or marrow

4. ≥20% blasts plus promyelocytes in blood or marrow

5. ≥20% basophils plus eosinophils in blood

6. Anemia or thrombocytopenia unresponsive to TKI

7. Persistent thrombocytosis

8. Additional chromosome changes (evolving new clone)

9. Increasing splenomegaly

10. Development of chloromas or myelofibrosis

11. Patient in a second (or subsequent) chronic phase after blast crisis