Hypereosinophilic syndrome - diagnostic and treatment approach

Hypereosinophilic syndrome is defined as a peripheral blood eosinophil count ? 1.5 ? 109/L associated with tissue or organ damage. Eosinophilic disorders represent a group of pathological conditions with heterogeneous pathophysiology, clinical presentation and prognosis. The disease prognosis is based on identifying the subtype and mechanism of eosinophilia. It is important to assess the degree of organ damage based on diagnostics that is directed upon symptoms and signs. After exclusion of secondary causes of eosinophilia, in 2016, the World Health Organization endorsed an assessment towards a molecular classification scheme of disease subtypes named clonal or primary eosinophilias. Diagnostic evaluation of primary eosinophilia relies on a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, flow immunophenotyping, and a T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic myeloid/lymphoid neoplasm. The goal of the therapy is to reduce eosinophil-mediated organ damage. Depending of cause of eosinophilia therapeutic implications range from a ?watch and wait? to the implementation of allogeneic hematopoietic stem cell transplantation.