Hyper eosinophilia associated with myeloid and lymphoid neoplasms

Eosinophilia in the absence of allergies, asthma, drug reactions, parasitic infections and connective tissue diseases can be eosinophilic clonal disorders, lymphoma or myeloproliferative disorders.
Hypereosinophilia with the persistence of eosinophils ≥1500 /mm³ in blood or more than 20% of eosinophils in the bone marrow may be observed in many reactive or clonal disorders, the result of which is invasion of organs and the secretion of granules and multi-organ failure. For a patient with hypereosinophilia, reactive causes such as allergies, asthma, medications, infections, autoimmune disorders, or solid tissue tumors should be investigated. If reactive causes are not found, primary eosinophilia should be considered.
According to the WHO revision 2016, FISH or RT-PCR for FIPIL1-PDGFRA fusion and cytogenetic and FISH for gene rearrangements on chromosomes 4q12 (PDGFRA), 5q31-33 (PDGFRB), 8p11-12 (FGFR1) and 9P24 (Jak2) are essential.
Chronic eosinophilic leukemia is considered in the presence of ≥1.5 × 109/L absolute eosinophil count. These patients should lack myeloproliferative family genetic markers (such as t (9;22) and Jak2, CARL and CMPL mutations) and also lack myeloid/lymphoid genetic rearrangements associated with eosinophilia (including PDGFRA, PDGFRB and FGFR1).