Laboratory findings

• red cells:
  • usually anaemia
  • cell morphology is abnormal with macrocytes, microcytes or bizarre shapes
  • MCV is normal or increased
    
    
• WBC:
  • usually normal or reduced; but raised in chronic myelomonocytic leukaemia where monocyte count may exceed 10 x 10^9 / l
  • neutropenia is common; neutrophils may be hypogranular with one or two segments (Pelger-Huet cells), or may be hypersegmented
    
    
• platelets - normal or reduced; some may be hypogranular
  
  
• bone marrow - hypercellular despite low counts:
  • erythroid hyperplasia is common - abnormalities include megaloblastoid changes, nuclear budding or multinucleate erythroid precursors
  • granulocyte precursors often lack cytoplasmic granules
  • dwarf megakaryocytes with unilobed nucleus are characteristic
    
    
• 60% of patients have chromosomal abnormalities most commonly 5, 7, 20, or Y, and trisomy 8.

Reference

1. Fenaux P, Haase D, Santini V, et al; ESMO Guidelines Committee. Myelodysplastic syndromes: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2021 Feb;32(2):142-56.