Eosinophilia in children: characteristics, etiology and diagnostic algorithm

Area of Science:

• Pediatric Hematology
• Clinical Immunology
• Allergy and Immunology

Background:

• Eosinophilia is a common finding in children, with various underlying causes.
• Limited large-cohort studies exist for childhood eosinophilia, especially mild cases.
• Understanding the etiology and developing diagnostic tools are crucial.

Purpose of the Study:

• To identify the underlying causes of eosinophilia in children.
• To develop a diagnostic algorithm for evaluating childhood eosinophilia based on severity.
• To investigate the association of specific conditions with eosinophilia.

Main Methods:

• Retrospective review of medical files for 1178 children (<18 years) with absolute eosinophil counts ≥0.5 × 10^9/L.
• Categorization of patients into mild, moderate, and severe eosinophilia groups.
• Logistic regression analysis to identify independent risk factors.

Main Results:

• Allergic diseases (80%) and primary immunodeficiencies (PIDs) (8.5%) were the most frequent causes.
• Allergic diseases predominated in mild/moderate eosinophilia, while PIDs were more common in severe cases.
• Food allergy and PIDs were identified as independent factors for childhood eosinophilia.

Conclusions:

• Childhood eosinophilia is frequently secondary to allergic diseases or PIDs.
• A severity-based diagnostic algorithm is practical for evaluating diverse etiologies of childhood eosinophilia.
• PIDs should be investigated in children with unexplained eosinophilia, particularly in regions with high consanguinity rates.