Myeloid/Lymphoid Neoplasms with eosinophilia and involvement of Tyrosine Kinase gene fusions (MLN‐TK) is a WHO disease category including a diverse group of malignancies characterised by recurrent genomic rearrangements of tyrosine kinase (TK) genes such as PDGFRA, PDGFRB, FGFR1, JAK2, ETV6 and FLT3. The gene discussed is JAK2; the disease is Increased total eosinophil count.