Chapter 1 – Diagnosis and classification of leukaemias

Classification of ALL and MDS

The FAB classification for ALL is no longer in use. The European Group for the Immunological Characterization of Leukaemias (EGIL) classification is based on the immunophenotype according to maturation markers.

The EGIL subgroups are informative about prognosis and guide treatment, e.g. early allogeneic transplantation.

The WHO 2016 classification defines genetic ALL subtypes. There is a special focus on BCR-ABL1-positive and Philadelphia-like ALL, which require targeted treatment.

MDS is a heterogeneous disease characterised by cytopaenia and single- or multilineage dysplasia.

Cytomorphologic diagnosis on bone marrow smears is gold standard. Certain genetic abnormalities such as 5q deletion are associated with good prognosis and respond to targeted treatment.

Analysis of somatic mutations revealed the continuum from healthy individuals to MDS and AML in the pathogenesis of disease (Steensma et al. 2015).

Patients with cytopaenia and certain somatic mutations can be diagnosed with CCUS – clonal cytopaenia of undetermined significance.

Spliceosome mutations or co-mutations with ASXL1, TET2 and DNMT3A in a patient with unexplained cytopaenia are highly predictive of a haematological malignancy.

The Revised International Prognostic Scoring System (IPSS-R) score is used for risk stratification: it defines risk groups according to karyotype, haemoglobin level and percentage of blast cells, platelet and neutrophil counts (Greenberg et al. 2012).

Revision Questions

  1. What is the basis for the EGIL ALL classification?
  2. What is the role of somatic mutations in a patient with cytopaenia?
  3. Which parameters are needed for risk stratification of MDS?

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Last update: 28 February 2019