Table 3.

Comparison of the criteria established by the ELN and the WHO for definition of the phase of CML.

Definition as Used by
Phase	European LeukemiaNet (ELN)	World Health Organization (WHO)
CML CP	<10% blasts in PB or in BM No criteria fulfilled for CML-AP or CML-BP	<10% blasts in PB or in BM No criteria fulfilled for CML-AP or CML-BP
CML-AP	Persistent thrombocytopenia (<100 × 10 9/L) unrelated to therapy >20% basophils in the PB 15–29% blasts in the PB and/or BM Sum of myeloblasts and promyelocytes >30% in the PB or BM with proportion of blasts <30%	Persistent or increasing WBC (>10 × 109/L), unresponsive to therapy Persistent or increasing splenomegaly, unresponsive to therapy Persistent thrombocytosis (>1000 × 109/L), unresponsive to therapy Persistent thrombocytopenia (<100 × 109/L) unrelated to therapy >20% basophils in the PB 10–19% blasts in the PB and/or BM Additional clonal chromosomal abnormalities (ACA) in Ph1 cells at diagnosis that include “major route” abnormalities (second Ph1, trisomy 8, isochromosome 17q, trisomy 19), complex karyotype, or abnormalities of 3q26.2 Any new clonal chromosomal abnormality in Ph1 positive cells that occurs during therapy
CML-BP	≥30% blasts in the blood, marrow or both Extramedullary infiltrates of leukemic cells (with the exception of spleen and liver)	≥20% blasts in the blood or BM the presence of an extramedullary accumulation of blasts (with the exception of spleen and liver) (As the onset of lymphoid BP may be quite sudden, the detection of any bona fide lymphoblasts in the blood or marrow should raise con-cern for a possible impending lymphoid BP, and prompt additional laboratory and genetic studies to exclude this possibility).