basofilia

Basophilia is a medical term used to describe an increased number of basophils, a type of white blood cell, in the peripheral blood. Basophils normally represent a small fraction of leukocytes, typically less than 1% of circulating white blood cells, with an absolute count usually below about 0.2 x 10^9/L. Basophilia is defined by an elevated absolute basophil count or a relative rise above the laboratory’s upper limit of normal, commonly an absolute count greater than 0.2 x 10^9/L or a relative proportion around 2% of white cells, though exact thresholds vary by laboratory.

Causes of basophilia include a range of conditions. Allergic reactions and atopic diseases (such as asthma, allergic rhinitis, and dermatitis) can cause transient basophilia. Chronic inflammatory states and certain infections may also raise basophil counts. Endocrine disorders, notably hyperthyroidism or Graves disease, have been associated with basophilia. In hematologic disorders, basophilia is particularly characteristic of myeloproliferative neoplasms, most notably chronic myeloid leukemia (CML), where basophil levels can be markedly elevated. Other myeloproliferative conditions, splenic disorders, and recovery from severe cytopenias may also be linked to increased basophils.

Pathophysiology involves the role of basophils in allergic and inflammatory responses, including release of histamine, heparin, leukotrienes, and cytokines such as IL-4 and IL-13. In clonal conditions, basophil production is driven by malignant myeloid proliferation and associated growth factors (for example, BCR-ABL1 in CML) and inflammatory cytokines such as IL-3 and GM-CSF.

Diagnosis relies on complete blood count with differential and review of the peripheral smear. If basophilia is persistent or accompanied by other abnormalities (leukocytosis, splenomegaly, cytogenetic changes), further evaluation—bone marrow examination and targeted molecular testing—may be indicated to identify an underlying cause. Treatment targets the underlying condition: allergen avoidance and symptomatic management for allergic reactions, and disease-specific therapy for myeloproliferative or hematologic disorders.