Chronic Myelogenous Leukemia (CML) Staging 

Updated: Jul 09, 2019
  • 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

Blasts < 10% in peripheral blood and bone marrow

Accelerated phase

  • Blasts 10-19% of white blood cells (WBCs) in peripheral and/or nucleated bone marrow cells
  • Peripheral blood myeloblasts and promyelocytes combined ≥30%
  • Peripheral blood basophils ≥20%
  • Persistent thrombocytopenia (< 100 × 10 9/L) unrelated to therapy or persistent thrombocytosis (> 1000 × 10 9/L) unresponsive to therapy
  • Increasing WBC counts and spleen size unresponsive to therapy
  • Additional clonal cytogenetic abnormalities in Philadelphia chromosome–positive cells

Blast crisis

  • Blasts ≥ 20% of peripheral blood WBCs or nucleated bone marrow cells
  • Extramedullary blast proliferation
  • 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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