Pediatric hypereosinophilia: characteristics, clinical manifestations and diagnoses

RATIONALE: Peripheral blood eosinophilia is associated with a variety of disorders, including parasitic infections and allergic and autoimmune diseases. The range of differential diagnoses is broad, and data on pediatric hypereosinophilia are limited.

METHODS: A retrospective chart review was completed and included all patients <18 years of age presenting to our institution between January 1, 2008 and May 31, 2017 with absolute eosinophil counts (AEC) >1,500 eosinophils/microliter on two occasions at least four weeks apart. We analyzed demographic characteristics, clinical manifestations, laboratory values, treatment course, and diagnoses.

RESULTS: The median age at presentation was 4.9 years (range 0.1–17.5, n = 203), and the median peak AEC was 3090 (range 1560–55,740) eosinophils/microliter. Notably, 17% (34/203) of the subjects were under the age of 1 year. There were slightly more males (115/203), and the median age at presentation for males was lower (3.2 [range 0.2 – 17.5] vs. 8.2 [range 0.1–17.4]). However, there were no differences in median peak AEC between males and females. There were six deaths during the study period. There was a seasonality to the incidence of hypereosinophilia, with the highest incidence in the summer (June–August, 58/192) and fall (September–November, 53/192) and lowest incidence in the winter (December–February, 34/192).

CONCLUSIONS: Hypereosinophilia has an incidence of around 20 individuals per year meeting diagnostic criteria at our institution, with the largest portion of individuals being under the age of 1 year. The highest incidence occurs during the summer and fall seasons, highlighting the affect of environmental exposures on pediatric hypereosinophilia.