The causes of a peripheral blood eosinophilia in a secondary care setting

World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary or clonal) disorders with the potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 109/L, and may be associated with tissue damage. After the exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of various tests. They include morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, molecular testing and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2022 World Health Organization and International Consensus Classification endorse a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-eo-TK), and the MPN subtype, "chronic eosinophilic leukemia" (CEL). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., <1.5 × 109/L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Pemigatinib was recently approved for patients with relapsed or refractory FGFR1-rearranged neoplasms. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, is approved by the U.S Food and Drug Administration for patients with idiopathic HES. Cytotoxic chemotherapy agents, and hematopoietic stem cell transplantation have been used for aggressive forms of HES and CEL, with outcomes reported for limited numbers of patients. Targeted therapies such as the IL-5 receptor antibody benralizumab, IL-5 monoclonal antibody depemokimab, and various tyrosine kinase inhibitors for MLN-eo-TK, are under active investigation.

Characteristics of patients with incidental eosinophilia admitted to a tertiary hospital in southern China

Background

The characteristics of patients with eosinophilia are heterogeneous and the outcomes can vary from asymptomatic to severe.

Objective

To describe the feature of patients with eosinophilia in a single center.

Design

Based on the electronic medical records from Yangjiang People's Hospital in China, the inpatients admitted between June 2018 and February 2021 with measured blood eosinophil counts were evaluated.

Methods

Eosinophilia was defined as a peripheral blood eosinophil count of ≥0.5 × 10⁹/L. Differences were compared by eosinophilia severity. The medical records of patients with moderate to severe eosinophilia were reviewed and summarized in terms of examination, diagnoses and management. And these patients were matched with patients without incidental eosinophilia by propensity score and the differences were compared.

Results

A total of 7,835 patients with eosinophilia were identified out of 131,566 total inpatients. All types of eosinophilia were most common in males (8.2%; 5,351/65,615), and in patients aged 0-6 years (11.6%; 1,760/15,204), and in the pediatric (10.8%; 1,764/16,336) department, followed by dermatology (10.6%; 123/1,162), Oncology (7.5%; 394/5,239) and Intensive care unit (ICU) (7.4%; 119/1,608). Patients with moderate to severe eosinophilia were more likely to admit to ICU (moderate: 1.3%; severe: 0.50%). In patients with moderate to severe eosinophilia, only 205/621 (33%) had eosinophilia mentioned in their records, and only 63/621 (10.1%) underwent investigations for eosinophilia. The majority of patients with moderate to severe eosinophilia (372/621, 59.9%) had an infectious disease, and little examination (7.4%; 46/621) was taken to identify the cause of eosinophilia, and only 39/621 (6.3%) of patients had a discrete cause of eosinophilia identified. Patients with moderate to severe eosinophilia (24.3%; 151/621) exhibited certain chance to have organ dysfunction.

Conclusion

Incidental eosinophilia in inpatients was frequently neglected and less investigated. Multidisciplinary consultation may improve outcomes of inpatients with moderate to severe eosinophilia.

Fungal exposome, human health, and unmet needs: A 2022 update with special focus on allergy

Humans inhale, ingest, and touch thousands of fungi each day. The ubiquity and diversity of the fungal kingdom, reflected by its complex taxonomy, are in sharp contrast with our scarce knowledge about its distribution, pathogenic effects, and effective interventions at the environmental and individual levels. Here, we present an overview of salient features of fungi as permanent players of the human exposome and key determinants of human health, through the lens of fungal allergy and other fungal hypersensitivity reactions. Improved understanding of the fungal exposome sheds new light on the epidemiology of fungal-related hypersensitivity diseases, their immunological substratum, the currently available methods, and biomarkers for environmental and medical fungi. Unmet needs are described and potential approaches are highlighted as perspectives.

Prevalence and management of eosinophilia based on periodic health examinations in primary care clinics

Background

Eosinophilia is a common, hematologic abnormality detected in periodic health checkups with diverse etiologies. There are a few clinical practice guidelines for the management of eosinophilia.

Objectives

To determine the prevalence of eosinophilia among patients undergoing periodic health examinations, evaluate its management and outcomes, and identify its associated factors.

Methods

We conducted a retrospective study that included patients with eosinophilia diagnosed during the 2018 periodic health examinations at Songklanagarind Hospital.

Results

The prevalence rate of eosinophilia was 9.6% (988/10,299), and most patients (52.6%) were male with a median age of 53.0 (42.0-61.0) years. Only 174 patients (17.6%) were diagnosed and further examined to identify the cause of eosinophilia; including an examination of medical history (18.4%), physical examination (93.1%), laboratory analysis (9.2%), and consultation with internists (14.9%). Empirical anthelmintic therapy was administered in 130 patients (74.7%), and 49.2% achieved resolution. The possible causes of eosinophilia were identified in 20.7% (204/988), the most common cause being atopic disease (51.5%). Patients with moderate-to-severe eosinophilia were significantly more likely to be diagnosed, undergo further laboratory tests, and proceed with consultations with internists (adjusted OR [95% CI] = 3.52 [1.97-6.32], 17.13 [5.74-51.11], and 6.38 [1.95-20.93], respectively).

Conclusions

Eosinophilia is commonly identified in periodic health examinations, and most primary physicians lack knowledge regarding the diagnostic work-up required to determine the cause of eosinophilia. Empirical anthelmintic therapy showed satisfactory efficacy for the management of eosinophilia in areas where parasite infection is endemic.

World Health Organization-defined eosinophilic disorders: 2022 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary or clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 10⁹ /L. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, next generation sequencing gene assays, and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2", and the myeloproliferative neoplasm subtype, "chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (eg, < 1.5 × 10⁹ /L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, was recently approved by the US Food and Drug Administration for patients with idiopathic HES. The use of the IL-5 receptor antibody benralizumab, as well as other targeted therapies such as JAK2 and FGFR1 inhibitors, is under active investigation.