An Approach to the Evaluation of Persistent Hypereosinophilia in Pediatric Patients

Abstract

Hypereosinophilia (HE) is currently defined by a peripheral blood absolute eosinophil count (AEC) of ≥1,500 cells/microL. Although mild blood eosinophilia (AEC 500–1,500 cells/microL) is observed relatively frequently within the pediatric population, persistent HE is uncommon and should prompt additional clinical evaluation. While the clinical manifestations and underlying etiologies of HE in adults have been well-characterized, there is a paucity of data on HE in children. Limited evidence suggests that many similarities between adult and pediatric HE likely exist, but some important differences remain between these populations. The evaluation of HE in children can be challenging given the broad differential diagnosis, which includes primary hematologic disorders and secondary eosinophilia in which the increased eosinophil levels are propagated by disease states that promote eosinophil production and survival. On the basis of the underlying etiology, clinical manifestations can range from benign, self-resolving elevations in the AEC to life-threatening disorders with the potential for significant end-organ damage. Given the broad differential diagnosis of HE, it remains essential to systematically approach the evaluation of unexplained HE in children. This review will discuss the differential diagnosis for pediatric HE, highlighting etiologies that are more prevalent within the pediatric population. Additionally, a summary of the epidemiology of pediatric HE will be presented, with focus on some of the differences that exist between pediatric and adult HE. Finally, a directed approach to the diagnostic evaluation of children with HE will be discussed.

Hypereosinophilia in an infant – case report. The role of eosinophils in selected diseases

“…According to the conventional division, HE is distinguished by primary and secondary (reactive) forms -occurring in response to many disease conditions [4]. The primary form of HE in children is rare and is associated with proliferative diseases such as chronic eosinophilic leukaemia, myeloid leukaemia, mastocytic leukaemia, myelodysplastic syndromes, and systemic mastocytosis [1,2]. Differential diagnosis of secondary eosinophilia includes the following: allergic reactions, metabolic diseases (e.g.…”

“…It is suggested routine complete blood count be performed with differential, ESR, CRP, hepatic tests, vitamin B12 concentration, tryptase, troponins, urinalysis, faecal culture, parasitological tests (coproscopic assessment, immunoenzymatic testing), and imaging studies for organ changes depending on medical history and physical examination. After excluding secondary causes, the diagnosis should be made for clonal eosinophilia, including bone marrow biopsy with an immunophenotyping, morphological and cytogenetic evaluation [2,3]. The treatment of secondary eosinophilia consists of the elimination of the disease that underlies the change.…”

“…Eosinophilia is defined as an increase in the absolute eosinophil count (AEC) in the peripheral blood or tissues above the accepted normal values [1,2]. We can distinguish mild eosinophilia (AEC within 500-1500 cells/µl), moderate (AEC 1500-5000 cells/µl), and severe (AEC > 5000 cells/µl) [2].…”

“…Threshold values of the number of eosinophils change with age, and they are higher in infants and young children [2]. In children, mild eosinophilia (AEC 500-1500 cells/µl) is observed relatively frequently, while hypereosinophilia (HE) (AEC ≥ 1500 cells/µl) is rare and requires careful diagnosis [2,3]. The aetiology of HE is varied.…”

“…The increase in the number of eosinophils present in the blood and tissues has been observed primarily in bone marrow proliferative diseases and, as a secondary form, in the course of many disease conditions, including most commonly parasitic infections and allergic diseases [1,3,4]. Children most frequently demonstrate secondary HE [2].…”