Chronic myelomonocytic leukaemia

**Definition:** A myelodysplastic/myeloproliferative neoplasm which is characterised by persistent monocytosis, absence of a Philadelphia chromosome and BCR/ABL1 fusion gene, fewer than 20 percent blasts in the bone marrow and blood, often myelodysplasia, and absence of PDGFRA or PDGFRB rearrangement.

**Inclusions:** - Chronic monocytic leukaemia

**Exclusions:** - Myeloid or lymphoid neoplasm associated with PDGFRA rearrangement - Myeloid neoplasm associated with PDGFRB rearrangement