Hypereosinophilia in Children and Adults: A Retrospective Comparison.

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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/µL; 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. CONCLUSIONS: 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.

Marked and persistent eosinophilia in the absence of clinical manifestations.

BACKGROUND: Although most patients with hypereosinophilic syndromes (HES) present with clinical signs and symptoms attributable to eosinophilic tissue infiltration, some untreated patients remain asymptomatic or have signs and symptoms, such as allergic rhinitis, for which the relationship to peripheral eosinophilia is unclear (hypereosinophilia of unknown significance [HEUS]). OBJECTIVE: To identify and characterize subjects with HEUS of 5 years duration or more as compared to untreated patients with symptomatic HES and healthy normal volunteers. METHODS: All subjects with eosinophilia underwent yearly evaluation, including a standardized clinical evaluation, whole blood flow cytometry to assess lymphocyte subsets and eosinophil activation, and serum collection. Peripheral blood mononuclear cells were cultured overnight with and without phorbol 12-myristate 13-acetate/ionomycin. Cytokines and chemokines were measured in serum and cell supernatants, and mRNA expression was assessed by using quantitative real-time PCR. RESULTS: Eight of the 210 subjects referred for the evaluation of eosinophilia (absolute eosinophil count [AEC] > 1500/µL) met the criteria for HEUS of 5 years duration or more (range, 7-29 years). Peak eosinophil count and surface expression of eosinophil activation markers were similar in subjects with HEUS and in untreated subjects with platelet-derived growth factor alpha-negative HES (n = 28). Aberrant or clonal T-cell populations were identified in 50% of the subjects with HEUS as compared to 29% of the subjects with HES (P = .12). Increased levels of IL-5, GM-CSF, IL-9, and IL-17A were also comparable in subjects with HEUS and HES. Serum levels of IgE and IL-13 were significantly increased only in subjects with HES. CONCLUSIONS: A small number of patients with persistent peripheral eosinophilia (AEC > 1500/µL) appear to have clinically benign disease.