Chronic Myelogenous Leukemia Staging 

Updated: Dec 30, 2015
  • Author: Sandy D Kotiah, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Phases of Chronic Myelogenous Leukemia

The 3 phases of chronic myelogenous leukemia (CML), as defined by the World Health Organization (WHO), [1, 2] are listed below.

Table. Phases of Chronic Myelogenous (Open Table in a new window)

CML phase

WHO definition

Chronic stable phase

Peripheral blood blasts fewer than 10% in the blood and bone marrow

Accelerated phase

Blasts 10-19% of white blood cells in peripheral and/or nucleated bone marrow cells ; persistent thrombocytopenia (< 100 × 109/L) unrelated to therapy or persistent thrombocytosis (> 1000 × 109/L) unresponsive to therapy; increasing white blood cells and spleen size unresponsive to therapy; cytogenetic evidence of clonal evolution

Blast crisis

Peripheral blood blasts ≥ 20% of peripheral blood white blood cells or nucleated bone marrow cells; extramedullary blast proliferation; and large foci or clusters of blasts on bone marrow biopsy

See Chronic Leukemias: 4 Cancers to Differentiate, a Critical Images slideshow, to help detect chronic leukemias and determine the specific type present.


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