Accelereret fase defineres som tilstedeværelse af én eller flere af følgende: blaster ≥15%, men < 30% i blod eller knoglemarv, blaster plus promyelocytter ≥30% i blod eller knoglemarv (hvilket giver < 30% blaster), perifere blodbasofiltal ≥20%, thrombocyttal < 100 x 109/ l uafhængigt af behandlingen.
Accelerated phase is defined by the presence of any of the following: blasts ≥ 15% but < 30% in blood or bone marrow, blasts plus promyelocytes ≥ 30% in blood or bone marrow (providing < 30% blasts), peripheral blood basophils ≥ 20%, platelets < 100 x 109/ l unrelated to therapy.