Chronic myeloid leukaemia, light micrograph. Chronic granulocytic leukaemia (chronic myeloid leukaemia, CML), is a slow-growing cancer of the white blood cells in which too many myeloblasts are found in the blood and bone marrow. It usually occurs in older adults. It is a type of myeloproliferative neoplasm associated with a characteristic chromosomal translocation called the Philadelphia chromosome, a reciprocal translocation, between chromosome 9 and chromosome 22. This blood smear shows a large number of myeloblasts in a case of CML.