Hypereosinophilia in Children and Adults: A Retrospective Comparison

The differential diagnosis of hypereosinophilia is broad and includes asthma, atopic disease, drug hypersensitivity, parasitic infection, connective tissue disorders, malignancy, and rare hypereosinophilic disorders. Hypereosinophilia in children has not been well characterized to date.

The objective of this study was to identify the common causes of marked eosinophilia in children and to characterize and compare the clinical symptoms at presentation, laboratory findings, final diagnosis, and therapeutic responses between children and adults with hypereosinophilic syndromes.

A retrospective analysis of consecutive subjects evaluated for unexplained eosinophilia ≥ 1.5 × 10(9)/L was conducted. All subjects underwent standardized clinical and laboratory evaluations with yearly follow-up. Clinical and laboratory parameters, final diagnoses, treatment responses, and outcomes were assessed. Medians and proportions were compared using Mann-Whitney U and Fisher Exact tests, respectively.

Of the 291 subjects evaluated, 37 (13%) were children and 254 were adults (87%). Whereas the frequencies of clinical hypereosinophilic syndrome (HES) variants were similar between children and adults, primary immunodeficiency was a more common secondary cause of HES in children (5% vs 0.4% in adults). Excluding subjects with treatable secondary causes, the median peak absolute eosinophil count was increased in pediatric subjects (9376 vs 5543/microL; P = .002), and children had more gastrointestinal complaints (62% vs 34%; P = .003) and less pulmonary involvement (34% vs 59%; P = .01) than adults. Despite these differences, corticosteroid responsiveness and overall prognosis were similar between the 2 groups.

Although children with HES often present with higher peak eosinophil counts than adults, the differential diagnosis, clinical characteristics, and prognosis of HES are similar in the 2 groups.