Myeloid neoplasms with eosinophilia are a clinically, morphologically, genetically, and prognostically heterogeneous group of clonal diseases characterized as follows:
- Initially, a persistent proliferation of clonal eosinophilic granulocytes in the peripheral blood.
- a hypercellular bone marrow
- if necessary, splenomegaly (Valent Pet al. 2012).
In morphology, the assessment of qualitative and quantitative changes in the non-eosinophil series (megakaryocytes, monocytes, mast cells, blasts) and bone marrow fibrosis is significant. By means of molecular genetic investigations, cytogenetic aberrations (e.g. reciprocal translocation, deletion, inversion, trisomy, complex karyotype), rearrangements of genes (FISH analysis), fusion genes (FISH analysis, RT-PCR) or mutations (allele-specific PCR, NGS) are included in the diagnosis. The causative genetic aberrations are characterized by a varying risk of progression into a myeloid or lymphoid blast phase (with a correspondingly unfavorable prognosis).