Atypical chronic myeloid leukemia (aCML)

  • 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

BCR-ABL1-negative atypical chronic myeloid leukemia (aCML) is a rare entity from the overlapping area of myelodysplastic and myeloproliferative diseases.

aCML - Classification

According to the WHO classification 2017, aCML is a leukemic disorder with myelodysplastic as well myeloproliferative features (MDS/MPN).


aCML WHO Classification 2017 (Swerdlow et al. 2017)

Myelodysplastic/myeloproliferative neoplasia

Atypical chronic myeloid leukaemia (aCML), BCR-ABL1-negative


Diagnostic criteria according to WHO 2017:

  • Peripheral blood leukocytosis ≥ 13x109/L, due to increased numbers of neutrophils and their precursors (i.e. promyelocytes, myelocytes and metamyelocytes), with neutrophil precursors constituting > 10% of the leukocytes
  • Dysgranulopoiesis, which may include abnormal chromatin clumping
  • No or minimal basophilia; basophils constitute < 2% of the peripheral blood leukocytes
  • No or minimal monocytosis; monocytes constitute < 10% of the peripheral blood leukocytes
  • Hypercellular bone marrow with granulocyte proliferation and granulocytic dysplasia, with or without dysplasia in the erythroid and megakaryocytic lineages
  • <20% blasts in the blood and bone marrow
  • No evidence of PDGFRA, PDGFRB or FGFR1 rearrangement, or of PCM1-JAK2
  • WHO criteria for BCR-ABL1-positive CML, PMF, PV or ET are not met

Diagnostics of aCML

Prognosis of aCML

A leukocyte count of >50x109/L has been described in several studies as a prognostically negative parameter for aCML (Onida et al. 2002, Breccia et al. 2006, Wang et al. 2014). In some of these studies, an age >65 years, female sex and a hemoglobin level of <10 g/dL were also prognostically unfavourable. Furthermore, a negative influence of a SETBP1 mutation was shown (Piazza et al. 2013). 30-40% of patients with aCML show a transformation into AML (Wang et al. 2014).

aCML - Recommendation

It should be noted that according to WHO 2017, within the framework of differential diagnoses, a CNL should be morphologically excluded if a CSF3R mutation is detected. Similarly, in the case of detection of a JAK2, CALR or MPL mutation, an accelerated phase of an MPN should be excluded based on the history.

In contrast, according to WHO 2017, the presence of a SETBP1 or ETNK1 mutation supports the diagnosis of atypical CML.

You may also be interested in

Career

As a rapidly growing, innovative medical laboratory, we are always looking for bright minds to help us bring new and more effective therapies to patients around the world.

Learn more

Services

Do you have questions about sample submission, analyses performed or findings? Here you will find contact details, contact persons and our most frequently asked questions (FAQs).

Learn more

Quality management

We have been certified according to national and international standards since 2009 and have successfully maintained these accreditations.

Learn more