Myelodysplastic syndromes

**Definition:** Clonal hematopoietic disorders characterised by dysplasia and ineffective hematopoiesis in one or more of the hematopoietic cell lines. The dysplasia may be accompanied by an increase in myeloblasts, but the number is less than 20% in marrow and blood, which, according to the WHO guidelines, is the requisite threshold for the diagnosis of acute myeloid leukaemia.

**Exclusions:** - Therapy-related myeloid neoplasms - Drug-induced aplastic anaemia