Eosinophilia

Eosinophila : A high eosinophil count of more than 0.5 × 109 /L is usually secondary to infection (especially parasites), allergy (e.g. eczema, asthma, reactions to drugs), immunological disorders(polyarteritis, sarcoidosis) or malignancy (e.g. lymphomas). Usually, such eosinophilia is short-lived.

       In the rarer primary disorders, there is a persistently raised, often clonal, eosinophilia, e.g. in myeloproliferative disorders, subtypes of acute myeloid leukaemia and idiopathic hypereosinophilic syndrome (HES). Recently, specific mutations in receptor tyrosine kinase genes have been found in some primary eosinophilias(e.g. causing rearrangements of platelet-derived factor receptors α and β or c-kit), which allow diagnosis and, in some cases, specific therapy with tyrosine kinase inhibitors such as imatinib.

   Eosinophil infiltration can damage many organs (e.g. heart, lungs, gastrointestinal tract, skin, musculoskeletal system); evaluation of eosinophilia therefore includes not only the identification of any underlying cause and its appropriate treatment but also assessment of any related organ damage.