Chronic myelogenous leukemia: ESMO clinical recommendations for diagnosis, treatment and follow-up.

Diagnosis is based on blood counts (leukocytosis and frequently also thrombocytosis) and differential (immature granulocytes, from the metamyelocyte to the myeloblast, and basophilia). Splenomegaly is present in >50% of cases of CML in the initial chronic phase, but 50% of patients are asymptomatic. Proof of diagnosis is attained by demonstration of the Philadelphia (Ph) chromosome (22q–) resulting from the balanced translocation t(9; 22) (q34;q11), and/or the BCR–ABL rearrangement in peripheral blood or bone marrow cells. In some cases ( 5%) a Ph chromosome cannot be detected and confirmation of diagnosis rests on molecular genetic methods, e.g. fluorescence in situ hybridization or reverse transcription– polymerase chain reaction (RT–PCR). Screening for BCR–ABL KD mutations is especially recommended in acceleration and/or blast crisis (for definition see below).