eosinofiilia

Eosinofiilia, more commonly spelled eosinophilia, is a medical term for an elevated number of eosinophils in the peripheral blood. Eosinophils are a type of white blood cell involved in defense against parasites and in allergic and inflammatory responses. Eosinophilia is usually defined as a circulating eosinophil count greater than about 500 cells per microliter, though thresholds may vary. When eosinophilia persists and causes organ damage or dysfunction, the condition may be described as hypereosinophilic syndrome (HES).

Causes are broadly categorized as reactive (secondary) and clonal (primary). Reactive eosinophilia can result from allergic diseases (asthma, allergic rhinitis, atopic dermatitis), parasitic infections, drug reactions, autoimmune diseases, and certain malignancies. Primary eosinophilia arises from clonal expansion of eosinophils due to myeloid neoplasms, including those with FIP1L1-PDGFRA or PDGFRB rearrangements, or other myeloproliferative disorders. In many cases the cause remains idiopathic.

Clinical features depend on the extent and duration of eosinophilia and on organ involvement. Many individuals are asymptomatic; others experience symptoms related to affected tissues, such as skin rashes or itching, respiratory symptoms (cough, wheeze), abdominal pain or diarrhea, or cardiac symptoms in eosinophilic myocarditis. Diagnosis relies on a CBC with differential, confirmation of persistent eosinophilia, and targeted workup to identify secondary causes and possible clonal disorders, including bone marrow analysis and molecular testing, along with organ-specific assessments.

Treatment aims to address the underlying cause and any organ damage. Mild reactive eosinophilia may require little or no treatment; persistent eosinophilia with organ involvement is treated with corticosteroids, and, in clonal cases, targeted therapies or cytoreductive agents. Management includes monitoring for relapse and organ function. Prognosis varies with cause and response to therapy.