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
  • 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 neoplasia, respectively. CMML is considered a myelodysplastic/myeloproliferative neoplasm according to the 2022 WHO classification. 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 (WHO 2022).

Table 1: Diagnostic criteria of CMML (WHO 2022)

Prerequisite criteria:

1.     Persistent absolute (≥0,5x109/L)­­ and relative (≥ 10%) peripheral blood monocytosis

2.     Blasts constitute <20% of the cells in the peripheral blood and bone marrow

3.     Not meeting diagnostic criteria of chronic myeloid leukemia or other myeloproliferative neoplasms

4.     Not meeting diagnostic criteria of myeloid/lymphoid neoplasms with eosinophilia and defining gene rearrangements (e.g. PDGFRA, PDGFRB, FGFR1 or JAK2)

Supporting criteria:

1.     Dysplasia involving ≥ 1 myeloid lineages

2.     Acquired clonal cytogenetic or molecular abnormality

3.     Abnormal partitioning of peripheral blood monocyte subsets

Requirements for diagnosis:

·         Pre-requisite criteria must be present in all cases

·         Monocytosis ≥ 1 × 109/L: one or more supporting criteria must be met

·         Monocytosis < 1 × 109/L: supporting criteria 1 and 2 must be met

Subtyping criteria:

·         MD-CMML: WBC count < 13x109/L

·         MP-CMML: WBC count ≥ 13x109/L

Subgrouping criteria (based on percentage of blasts and promonocytes):

·         CMML-1: <5% in peripheral blood and <10% in bone marrow

·         CMML-2: 6-19% in peripheral blood and 10-19% in bone marrow

Diagnostics of CMML

CMML: Prognosis

The median survival of patients with CMML is 2-3 years and the risk of AML transformation is 15-30% (WHO 2022). During the course of the disease, expansion of genetic alterations as well as the appearance of further genetic aberrations may occur, so that the investigation of changes in the karyotype as well as somatic mutations is also recommended during the course, as it may bring therapeutic consequences (Onkopedia guideline CMML).

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). Among others, the cytogenetic risk group (low: normal karyotype, loss of the Y chromosome; intermediate: other anomalies; high: trisomy 8, complex karyotype, anomalies of chromosome 7) or the mutation status of the ASXL1, NRAS, RUNX1 and SETBP1 genes is taken into account.

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

Status: October 2024

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