Chronic myelomonocytic
leukemia (CMML)

  • Method:
  • Anticoagulant:
  • Recommendation:
  • Method:
    Cytomorphology
  • Anticoagulant:
    EDTA
  • Recommendation:
    obligatory
  • Method:
    Immunophenotyping
  • Anticoagulant:
    EDTA or Heparin
  • Recommendation:
    facultative
  • Method:
    Chromosome analysis
  • Anticoagulant:
    Heparin
  • Recommendation:
    obligatory
  • Method:
    FISH
  • Anticoagulant:
  • Recommendation:
    no
  • Method:
    Molecular genetics
  • Anticoagulant:
    EDTA or Heparin
  • Recommendation:
    obligatory

Based on the current guidelines and the current state of research, there are different diagnostic recommendations for patients with chronic myelomonocytic leukemia. We have summarized the most important information on classification and diagnostic methods at the MLL. In addition, we provide further links on the prognosis in CMML, so that you can inform yourself in more detail.

CMML: Classification

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic disorder and is characterized by overlapping features of a myeloproliferative disorder and a myelodysplastic syndrome, respectively. CMML is considered a myelodysplastic/myeloproliferative neoplasm according to the 2017 WHO classification (Swerdlow et al. 2017). With the appearance of a new WHO classification, there will be some changes in diagnostic criteria. CMML is classified based on leukocyte count into the subgroups myelodysplastic CMML (MD-CMML) with <13x109/L leukocytes and myeloproliferative CMML (MP-CMML) with ≥13x109/L (Khoury et al. 2022).


Diagnostic criteria

  • Persistent peripheral blood monocytosis ≥1x109/L (Swerdlow et al. 2017); in the future: persistent monocytosis ≥0,5x109/L; when absolute monocytosis is ≥0.5 ×109/L but <1.0 ×109/L, detection of one of more clonal cytogenetic or molecular abnormality and documentation of dysplasia in at least one lineage are required for diagnosis (Khoury et al. 2022)
  • Monocytes accounting for ≥10% of the leukocytes in peripheral blood
  • No BCR-ABL1 rearrangement and no PDGFRA, PDGFRB or PCM1-JAK2 rearrangement
  • Blasts constitute <20% of the cells in peripheral blood and bone marrow
  • Classically dysplasia in one or more myeloid lineages
  • The criteria for the presence of PMF, PV or ET must not be met

If myelodysplasia is absent or minimal but the other criteria for CMML are met, CMML can be diagnosed if an acquired clonal cytogenetic or molecular genetic alteration is present or if monocytosis has persisted for at least three months for which all other possible causes (e.g., malignancy, infection, inflammation) have been excluded (Swerdlow et al. 2017).

Diagnostics of CMML

CMML: Prognosis

The median survival of patients with CMML is 20-40 months, with 15-30% of patients showing progression to AML (Swerdlow et al. 2017). MP-CMML is associated with a worse prognosis than MD-CMML (Khoury et al. 2022).

Prognosis can be assessed using the CPSS (CMML-specific prognostic scoring system) (Such et al. 2013) and the CPSS-molecular (Elena et al. 2016), or the Düsseldorf score if cytogenetic and molecular genetic data are not available (Onkopedia guideline CMML).

Here you can access the online calculators for the CPSS-Score and the CPSS-Mol-Score.

Status: July 2022

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