Myelodysplastic syndromes

Keywords: Myelodysplastic syndromes - classification, MDS, Pre-leukaemia

Key information

Appropriate Tests

A group of clonal haemopoietic stem cell disorders which are characterised by cytopenia(s), dysplasia and ineffective haematopoiesis in one or more of the major haemopoietic cell lines, and an increased propensity of transformation to acute myeloid leukaemia.

  • Recommended threshold for cytopenias are Hb <100g/L, absolute neutrophil count <0.8 x 10^9/L, and platelets <100 x 10^9/L (R-IPSS). However, values above these thresholds do not invalidate a diagnosis of a MDS if definitive morphological changes and cytogenetic abnormalities are found.
  • The term 'myelodysplastic syndrome' needs to be distinguished from the descriptive terms 'dysplastic changes', which do not necessarily imply a diagnosis of the former.

 
There may be an accompanying increase of myeloblasts but by definition, the bone marrow blast population accounts for <20% of nucleated cells.

 

Investigations:

Full blood count, Blood film - features include cytopenias, abnormal morphology in red/white cells and platelets and occasionally the presence of blasts.

Bone marrow biopsy - Bone marrow aspirate and trephine important for quantifying blast count and assessment of degree of dysplasia (usually requires >10% of cells in a particular lineage), and for assessment of presence of ring sideroblasts.

Cytogenetics - oncology - important for risk stratification: Revised International Prognostic Staging System (R-IPSS) now recognises 5 classes of cytogenetic changes (very good, good, intermediate, poor and very poor).

For classification see Table 8.

The WHO 2008 classification also includes a category of myelodysplastic/myeloproliferative neoplasms which includes:

  • Atypical chronic myeloid leukaemia, BCR-ABL1 negative
  • Juvenile myelomonocytic leukaemia
  • Chronic myelomonocytic leukaemia
  • Myelodysplastic / Myeloproliferative neoplasms, unclassifiable

 

See also Sideroblastic anaemia, Monocytosis.