Proposed refined diagnostic criteria and classification of eosinophil disorders and related syndromes

From evidence to practice: A systematic review-based diagnostic algorithm for paediatric eosinophilia across socioeconomic context

AIM

Paediatric eosinophilia is a common clinical dilemma, often leading to resource- and time-consuming assessments. We aim to evaluate the main aetiologies of eosinophilia in children from different socioeconomic settings and propose a diagnostic algorithm.

METHODS

A systematic literature review was conducted through PubMed, Embase and the Cochrane Library. Studies published from January 2012 to June 2023 reporting the incidence and aetiology of peripheral eosinophilia in children were included. Evidence from studies on children originating from low- or high-income countries was compared.

RESULTS

A total of 15 observational studies, encompassing 3409 children, were included. The causes of eosinophilia varied based on the children's origin and the eosinophilia severity. In children from high-income countries, allergic diseases were the leading cause, with a prevalence of 7.7%-78.2%, while parasitosis ranged from 1.0% to 9.1%. In children from low-income countries, parasitosis was predominant, ranging from 17.7% to 88.3%, although allergic diseases were found in 2.5%-4.8% of cases. Concerning severity, allergic diseases were the leading cause of mild-to-moderate eosinophilia; parasitosis was associated with moderate-to-severe eosinophilia, while immunological disorders were mostly found in severe cases.

CONCLUSION

We developed a step-up diagnostic algorithm that considers the child's origin and eosinophilia severity and could optimise resource allocation.

Anti-IL-5 Pathway Agents in Eosinophilic-Associated Disorders Across the Lifespan

Monoclonal antibodies targeting interleukin (IL)-5 pathways have revolutionized the treatment expectations for eosinophilic-associated conditions, particularly in patients with respiratory involvement. Mepolizumab (IL-5 antagonist monoclonal antibody), benralizumab (IL-5 receptor blocker monoclonal antibody), and reslizumab (IL-5 antagonist monoclonal antibody) have collectively contributed to the overall improvement of the disease burden in various conditions. Eosinophilic asthma currently boasts the most robust evidence across all age groups: all three biologics are approved for adults (aged ≥18 years); mepolizumab is approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) also in children (aged ≥ 6 years), while bernalizumab was recently approved by the FDA for patients aged ≥6 years in the USA. In chronic rhinosinusitis with nasal polyps, subcutaneous mepolizumab is the only anti-IL-5 therapy approved so far and can be used in adult patients (aged ≥18 years). For eosinophilic esophagitis, conflicting evidence surrounds both mepolizumab, reslizumab, and benralizumab, leading to non-approval of these agents by the FDA/EMA. Recently, mepolizumab was approved for eosinophilic granulomatosis with polyangiitis patients aged ≥6 years or older and for hypereosinophilic syndrome adult patients. A phase III trial proving noninferiority of benralizumab versus mepolizumab in eosinophilic granulomatosis with polyangiitis has been recently published, while evidence on reslizumab is scant. Overall, current evidence on anti-IL-5 biologics for eosinophilic-associated disorders is mostly focused on adults, whereas data for individuals aged under 18 years and over 65 years are scarce, resulting in a lack of evidence, particularly regarding efficacy, for the use of anti-IL-5 agents in these specific patient populations. This review addresses high-quality evidence from randomized controlled trials and real-world post-marketing studies regarding the use of anti-IL-5 therapies for eosinophilic-associated disorders across all age groups, spanning childhood, adulthood, and older age.

Safety, pharmacokinetics and pharmacodynamics of SHR-1703, an innovative long-acting anti-interleukin-5 monoclonal antibody, in healthy subjects: a randomized, double-blind, dose-escalation, placebo-controlled phase I study

OBJECTIVE

SHR-1703 is a novel humanized IgG1 monoclonal antibody with high IL-5 affinity and prolonged half-life, aiming to control eosinophil-related diseases. The study intended to evaluate pharmacokinetics, pharmacodynamics, immunogenicity, safety, and tolerability of SHR-1703 in healthy subjects.

METHODS

A single-center, randomized, double-blind, placebo-controlled, single-dose escalation phase I study was conducted. 42 subjects were allocated to sequentially receive single subcutaneous injection of 20, 75, 150, 300, and 400 mg SHR-1703 or placebo.

RESULTS

After administration, SHR-1703 was slowly absorbed with median Tmax ranging from 8.5 to 24.5 days. Mean t1/2 in 150 to 400 mg doses was 86 to 100 days. Cmax and AUC increased in nearly dose-proportional pattern over range of 75 to 400 mg SHR-1703. After receiving SHR-1703, peripheral blood eosinophils (EOS) greatly decreased from baseline, which showed no significant change from baseline in placebo group. Magnitude and duration of reduction of EOS rose with increased dosing of SHR-1703. In 400 mg dose, remarkable efficacy of reducing EOS maintained up to approximately 6 months post single administration. Moreover, SHR-1703 exhibited low immunogenicity (2.9%), favorable safety, and tolerability in healthy subjects.

CONCLUSION

Pharmacokinetics, pharmacodynamics, immunogenicity, safety, and tolerability of SHR-1703 support further clinical development of SHR-1703 in eosinophil-associated diseases.

CLINICAL TRIAL REGISTRATION

The study was registered on the ClinicalTrials.gov (identifier: NCT04480762).

Involvement of the JAK-STAT pathway in the molecular landscape of tyrosine kinase fusion-negative hypereosinophilic syndromes: A nationwide CEREO study

We investigated using a custom NGS panel of 149 genes the mutational landscape of 64 consecutive adult patients with tyrosine kinase fusion-negative hypereosinophilia (HE)/hypereosinophilic syndrome (HES) harboring features suggestive of myeloid neoplasm. At least one mutation was reported in 50/64 (78%) patients (compared to 8/44 (18%) patients with idiopathic HE/HES/HEUS used as controls; p < .001). Thirty-five patients (54%) had at least one mutation involving the JAK-STAT pathway, including STAT5B (n = 18, among which the hotspot N642H, n = 13), JAK1 (indels in exon 13, n = 5; V658F/L, n = 2), and JAK2 (V617F, n = 6; indels in exon 13, n = 2). Other previously undescribed somatic mutations were also found in JAK2, JAK1, STAT5B, and STAT5A, including three patients who shared the same STAT5A V707fs mutation and features consistent with primary polycythemia. Nearly all JAK-STAT mutations were preceded by (or associated with) myelodysplasia-related gene mutations, especially in RNA-splicing genes or chromatin modifiers. In multivariate analysis, neurologic involvement (hazard ratio [HR] 4.95 [1.87-13.13]; p = .001), anemia (HR 5.50 [2.24-13.49]; p < .001), and the presence of a high-risk mutation (as per the molecular international prognosis scoring system: HR 6.87 [2.39-19.72]; p < .001) were independently associated with impaired overall survival. While corticosteroids were ineffective in all treated JAK-STAT-mutated patients, ruxolitinib showed positive hematological responses including in STAT5A-mutated patients. These findings emphasize the usefulness of NGS for the workup of tyrosine kinase fusion-negative HE/HES patients and support the use of JAK inhibitors in this setting. Updated classifications could consider patients with JAK-STAT mutations and eosinophilia as a new "gene mutated-entity" that could be differentiated from CEL, NOS, and idiopathic HES.

Targeting CCR4 with mogamulizumab in refractory CD3-CD4+ lymphocytic-variant hypereosinophilic syndrome

Not available.

Prognostic factors of idiopathic hypereosinophilic syndrome: A nationwide survey in Japan

Idiopathic hypereosinophilic syndrome (iHES) is a condition wherein persistent hypereosinophilia associated with end-organ damage occurs without any known causes. Due to the rarity of the disease, insufficient knowledge has been accumulated. We therefore conducted a retrospective, multicentre, nationwide survey on iHES in Japan. A total of 57 patients were identified. For 43 patients who received any treatment, all cases were first treated with corticosteroids. An eosinophil percentage of less than 30% in the bone marrow and the absence of oedema were identified as factors associated with steroid dependency. The 5-year overall survival was 88.2%, and five patients died during follow-up; factors associated with worse overall survival were age >50, haemoglobin <12 g/dL, activated partial thromboplastin time >34 s, the presence of dyspnoea, the presence of thrombotic tendency and the presence of renal failure. Given the rarity of fatalities in our cohort, time-to-next-treatment (TTNT) was further analysed; the presence of renal failure, splenomegaly and lung abnormalities were associated with worse TTNT. Our nationwide study not only demonstrated clinical characteristics and the outcome of patients with iHES but also for the first time revealed clinical factors associated with steroid dependency and duration of first-line corticosteroid efficacy.

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.

Ophthalmic vascular manifestations in eosinophil-associated diseases: a comprehensive analysis of 57 patients from the CEREO and EESG networks and a literature review

Introduction

Eosinophils have widespread procoagulant effects. In daily practice, eosinophil-related cardiovascular toxicity consists of endomyocardial damage, eosinophilic vasculitis and arterial or venous thrombosis. Here we aim to report on the clinical features and treatment outcomes of patients with unexplained ophthalmic vascular manifestations and eosinophilia.

Methods

We conducted a retrospective, multicenter, observational study and a literature review of patients with eosinophilia (≥0.5 x109/L) and concomitant ophthalmic vascular manifestations independent of the underlying eosinophilic disease but with no alternative cause for ophthalmic manifestations.

Results

Fifty-seven patients were included (20 from the observational study and 37 from the literature review). Ophthalmic vascular features were the initial manifestation of eosinophil-related disease in 34 (59%) patients and consisted of 29 central retinal artery occlusions, six branch retinal artery occlusions, five central retinal vein occlusions, two branch retinal vein occlusions, seven retinal vasculitides, two retinal vasospasms, 12 Purtscher's retinopathies, 13 anterior ischemic optic neuropathies and two posterior ischemic optic neuropathies. The median [IQR] absolute eosinophil count at onset of ophthalmic vascular manifestations was 3.5 [1.7-7.8] x109/L. Underlying eosinophil-related diseases included eosinophilic granulomatosis with polyangiitis (n=32), clonal hypereosinophilic syndrome (HES) (n=1), idiopathic HES (n=13), lymphocytic HES (n=2), adverse drug reactions (n=3), parasitosis (n=2), polyarteritis nodosa (n=1), IgG4-related disease (n=1), eosinophilic fasciitis (n=1) and primary sclerosing cholangitis (n=1). Other extra-ophthalmologic arterial or venous thromboses related to eosinophilia were reported in four (7%) and nine (16%) patients, respectively. Visual prognosis was poor: only eight (10%) patients achieved full recovery of ophthalmologic symptoms. After a median follow-up of 10.5 [1-18] months, one patient (3%) had a recurrence of an ophthalmic vascular manifestation, and three patients (10%) had a recurrence of other vascular symptoms (deep vein thrombosis in two and pulmonary embolism in one patient). At the time of recurrence, absolute eosinophil counts were above 0.5 x109/L in all cases (n=4).

Discussion

This study broadens the spectrum of vascular manifestations associated with hypereosinophilia by adding ophthalmic vascular manifestations. In patients with ophthalmological vascular manifestations and hypereosinophilia, aggressive treatment of the underlying pathology (and normalization of blood count) should be implemented.

Eosinophils in Oral Disease: A Narrative Review

The prevalence of diseases characterised by eosinophilia is on the rise, emphasising the importance of understanding the role of eosinophils in these conditions. Eosinophils are a subset of granulocytes that contribute to the body's defence against bacterial, viral, and parasitic infections, but they are also implicated in haemostatic processes, including immunoregulation and allergic reactions. They contain cytoplasmic granules which can be selectively mobilised and secrete specific proteins, including chemokines, cytokines, enzymes, extracellular matrix, and growth factors. There are multiple biological and emerging functions of these specialised immune cells, including cancer surveillance, tissue remodelling and development. Several oral diseases, including oral cancer, are associated with either tissue or blood eosinophilia; however, their exact mechanism of action in the pathogenesis of these diseases remains unclear. This review presents a comprehensive synopsis of the most recent literature for both clinicians and scientists in relation to eosinophils and oral diseases and reveals a significant knowledge gap in this area of research.

[Eosinophils in otorhinolaryngology: friend or foe?]

This article summarizes the essential aspects of current knowledge about eosinophils, classifies eosinophilia in terms of the dimensions healthy or harmful reaction, takes a specific look at eosinophils in the field of otorhinolaryngology, and gives recommendations for diagnostic workup and therapeutic intervention in case of proven eosinophilia, particularly as an adverse drug reaction. The thoughts are inspired by communications at the 29th Congress of the European Rhinologic Society in Sofia, Bulgaria, 2023.

Clinical and Therapeutic Intervention of Hypereosinophilia in the Era of Molecular Diagnosis

Hypereosinophilia (HE) presents with an elevated peripheral eosinophilic count of >1.5 × 109/L and is composed of a broad spectrum of secondary non-hematologic disorders and a minority of primary hematologic processes with heterogenous clinical presentations, ranging from mild symptoms to potentially lethal outcome secondary to end-organ damage. Following the introduction of advanced molecular diagnostics (genomic studies, RNA sequencing, and targeted gene mutation profile, etc.) in the last 1-2 decades, there have been deep insights into the etiology and molecular mechanisms involved in the development of HE. The classification of HE has been updated and refined following to the discovery of clinically novel markers and targets in the 2022 WHO classification and ICOG-EO 2021 Working Conference on Eosinophil Disorder and Syndromes. However, the diagnosis and management of HE is challenging given its heterogeneity and variable clinical outcome. It is critical to have a diagnostic algorithm for accurate subclassification of HE and hypereosinophilic syndrome (HES) (e.g., reactive, familial, idiopathic, myeloid/lymphoid neoplasm, organ restricted, or with unknown significance) and to follow established treatment guidelines for patients based on its clinical findings and risk stratification.

Eosinophilic Patterns in Patients with Seasonal Allergy Affected by Bronchial Asthma and Rhinitis/Rhinosinusitis: Efficacy of Benralizumab in Patients with the Persistent Pattern

BACKGROUND

Eosinophilia can be influenced by multiple factors. This study aims to set a protocol for monitoring blood absolute eosinophil count (AEC) in patients with seasonal allergy affected by bronchial asthma (BA), allergic rhinitis (AR), or chronic rhinosinusitis with or without nasal polyposis (CRSw/sNP).

METHODS

We planned a total of four annual blood samples to measure AEC in- and out-seasonal pollen exposure (i.e., one measurement every three months for one year).

RESULTS

We identified two distinct groups of patients (non-eosinophilic and eosinophilic). Patients in the eosinophilic group presented with four different patterns (episodic, transient, floating, and persistent). Most patients with episodic, transient, and floating patterns were affected by mild allergy and the increase in eosinophils was related to allergen exposure. In contrast, patients with the persistent pattern mostly presented with more severe allergy (i.e., severe BA and relapsing CRSwNP) and the eosinophilia was unrelated to allergen exposure. The subgroup of patients with severe BA, relapsing CRSwNP, and persistent eosinophilc pattern were treated with benralizumab, which induced a noteworthy improvement in both severe BA and CRSwNP.

CONCLUSIONS

Multiple AEC measurements in patients with seasonal allergy can better reflect patient's eosinophilic status and help define the relationship of AEC enhancement with allergen exposure.

[Guideline of the diagnosis and treatment of eosinophilic disorders (2024)]

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary or clonal) disorders with potential for end-organ damage. Based on new clinical data and increased understanding of disease molecular genetics, the World Health Organization (WHO) and the international consensus classification (ICC) has provided updated criteria and classifications for eosinophilic disorders in 2022. This guideline represents an update of Chinese expert consensus on the diagnosis and treatment of eosinophilia published in 2017 and aim to provide Chinese hematologist with clear guidance on management for eosinophilic disorders.

Hematological Neoplasms with Eosinophilia

Eosinophils in peripheral blood account for 0.3-5% of leukocytes, which is equivalent to 0.05-0.5 × 109/L. A count above 0.5 × 109/L is considered to indicate eosinophilia, while a count equal to or above 1.5 × 109/L is defined as hypereosinophilia. In bone marrow aspirate, eosinophilia is considered when eosinophils make up more than 6% of the total nuclear cells. In daily clinical practice, the most common causes of reactive eosinophilia are non-hematologic, whether they are non-neoplastic (allergic diseases, drugs, infections, or immunological diseases) or neoplastic (solid tumors). Eosinophilia that is associated with a hematological malignancy may be reactive or secondary to the production of eosinophilopoietic cytokines, and this is mainly seen in lymphoid neoplasms (Hodgkin lymphoma, mature T-cell neoplasms, lymphocytic variant of hypereosinophilic syndrome, and B-acute lymphoblastic leukemia/lymphoma). Eosinophilia that is associated with a hematological malignancy may also be neoplastic or primary, derived from the malignant clone, usually in myeloid neoplasms or with its origin in stem cells (myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions, acute myeloid leukemia with core binding factor translocations, mastocytosis, myeloproliferative neoplasms, myelodysplastic/myeloproliferative neoplasms, and myelodysplastic neoplasms). There are no concrete data in standardized cytological and cytometric procedures that could predict whether eosinophilia is reactive or clonal. The verification is usually indirect, based on the categorization of the accompanying hematologic malignancy. This review focuses on the broad differential diagnosis of hematological malignancies with eosinophilia.

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Hypereosinophilic syndrome with massive liver infarction: A case report

RATIONALE

Liver infarction caused only by hepatic artery occlusion is rare. Elevated levels of eosinophils in the blood and tissue can have devastating consequences.

PATIENT CONCERNS

Male, 21 years old, presented with persistent abdominal distension and discomfort for more than ten days without an apparent cause. Laboratory findings showed an eosinophil percentage of 32.5% (normal range 0.5%-5%). Computed tomographic angiography of the hepatic artery and its branches did not show any enhancement, only the common hepatic artery was visible.

DIAGNOSIS

The patient in this case had a peripheral blood eosinophil count of ≥1.5 × 109/L in multiple examinations over 6 months, and eosinophilic leukemia and secondary causes such as parasitic infections, allergic diseases, or tumors were ruled out, confirming the diagnosis of hypereosinophilic syndrome (HES).

INTERVENTIONS

The patients were treated with interventional therapy, glucocorticoid pulse therapy and anti-infection therapy.

OUTCOMES

After interventional therapy, glucocorticoid pulse therapy, and anti-infection treatment, the patient was reexamined 2 months later. The CT scan showed that the range of the original infarction in the liver had shrunk compared to before, and the remaining liver had enlarged with good compensation; Laboratory tests improved compared with baseline: eosinophil percentage of 0.1%.

LESSONS

This article discusses a rare case of hepatic artery occlusion and liver infarction in a young male patient with HES. The cause of hepatic artery embolism and hepatic infarction may be related to the abnormal increase in eosinophils, which can lead to hypercoagulation and thrombus formation. The article emphasizes the importance of timely diagnosis and treatment of HES to prevent life-threatening thrombotic events and describes the successful management of the patient condition through anticoagulation, anti-infection, liver protection, and glucocorticoid therapy.

[IgG4-related disease: A proteiform pathology with frequent chest manifestations]

INTRODUCTION

While IgG4-related disease (IgG4-RD) was initially described in the early 2000s, its polymorphic clinical manifestations were previously reported under different names ; they have in common the presence of IgG4+ oligoclonal plasma cells and fibrosis.

STATE OF THE ART

Ruling out certain differential diagnoses, the diagnosis of IgG4-RD is based on a bundle of clinical, biological and histological features. Chest involvement is variable and can affect the mediastinum, bronchi, parenchyma, pleura and/or, more rarely, bones and (pericardium, aorta, coronary…) vascular structures. The most frequent radiological manifestations are peribronchovascular thickening, mediastinal lymphadenopathy, and nodular or interstitial patterns. Pleural involvement and posterior mediastinal fibrosis are less frequent, while thoracic paravertebral tissue thickening is highly specific. Systemic corticosteroids are the cornerstone of treatment. In case of relapse or as frontline therapy in case of risk factors for relapse and/or poor tolerance of corticosteroids), a steroid-sparing agent (most often rituximab) is added, and biannual maintenance infusions are associated with a lower risk of relapse.

PERSPECTIVES

An international consensus has recently led to the development of classification criteria that should standardize the diagnostic approach and homogenize the enrolment of patients in epidemiological as well as therapeutic studies. Other treatments are also under evaluation, including biologics targeting T2 inflammation, CD-19 (inebilizumab, obexelimab), SLAMF7 (elotuzumab) surface proteins, Bruton's tyrosine kinase, and the JAK/STAT pathway.

CONCLUSIONS

Substantial progress has been made over recent years in understanding IgG4-RD pathophysiology, and personalized patient care seems to be an achievable medium-term goal.

Nomenclature of allergic diseases and hypersensitivity reactions: Adapted to modern needs: An EAACI position paper

The exponential growth of precision diagnostic tools, including omic technologies, molecular diagnostics, sophisticated genetic and epigenetic editing, imaging and nano-technologies and patient access to extensive health care, has resulted in vast amounts of unbiased data enabling in-depth disease characterization. New disease endotypes have been identified for various allergic diseases and triggered the gradual transition from a disease description focused on symptoms to identifying biomarkers and intricate pathogenetic and metabolic pathways. Consequently, the current disease taxonomy has to be revised for better categorization. This European Academy of Allergy and Clinical Immunology Position Paper responds to this challenge and provides a modern nomenclature for allergic diseases, which respects the earlier classifications back to the early 20th century. Hypersensitivity reactions originally described by Gell and Coombs have been extended into nine different types comprising antibody- (I-III), cell-mediated (IVa-c), tissue-driven mechanisms (V-VI) and direct response to chemicals (VII). Types I-III are linked to classical and newly described clinical conditions. Type IVa-c are specified and detailed according to the current understanding of T1, T2 and T3 responses. Types V-VI involve epithelial barrier defects and metabolic-induced immune dysregulation, while direct cellular and inflammatory responses to chemicals are covered in type VII. It is notable that several combinations of mixed types may appear in the clinical setting. The clinical relevance of the current approach for allergy practice will be conferred in another article that will follow this year, aiming at showing the relevance in clinical practice where various endotypes can overlap and evolve over the lifetime.

Case report: Serious unexpected vascular events in two patients with lymphocytic variant hypereosinophilic syndrome

Background

Lymphocytic-variant hypereosinophilic syndrome (L-HES) is a form of reactive hypereosinophilia, most commonly associated with interleukin-5 over-production by clonal, most commonly CD3-CD4+CD2hiCD5hiCD45RO+ T-cells. Patients often present with predominant cutaneous and soft-tissue manifestations, while cardiovascular involvement is uncommon.

Methods

We reviewed the medical files of two L-HES patients followed in our center who developed serious vascular complications and performed a literature review for similar cases.

Results

Patient 1, a 52-year-old female, presented with an ischemic stroke secondary to left middle cerebral artery dissection after 10 years of indolent L-HES. Blood eosinophilia was controlled with oral corticosteroids (OCS), but OCS-tapering attempts with hydroxyurea and pegylated interferon failed, prompting the introduction of mepolizumab with rapid normalization. Patient 2, a 62-year-old female, had been asymptomatic for 10 years without treatment when a NSTEMI occurred, due to coronary artery occlusion secondary to a large cauliflower-aneurysm of the proximal aorta and aneurysmal dilatation of several coronary arteries, requiring semi-urgent surgical management. Aortic wall staining for eosinophil major basic protein showed eosinophils in the adventitia. Blood eosinophilia was controlled with OCS.

Conclusions

Patients with apparently clinically benign L-HES may develop arterial complications, consisting in dissection and/or aneurysm dilatation of medium-to-large vessels with serious consequences. The value of performing regular vascular imaging and monitoring during follow-up has yet to be determined.

Low-dose anti-IL 5 treatment in idiopathic hypereosinophilic syndrome: towards a precision medicine approach for remission maintenance

Mepolizumab at the dose of 300 mg/4 weeks has been recently approved as an add-on therapy for patients with uncontrolled hypereosinophilic syndrome (HES) without any identifiable non-hematologic secondary cause. According to the available real-life evidence mepolizumab 300 mg and 100 mg, licensed for severe eosinophilic asthma, are comparable in terms of drug efficacy. However, the clinical rationale for selecting one dose or the other has not been explored. We investigated the efficacy and safety of mepolizumab 100 mg in idiopathic HES (I-HES) patients as a steroid sparing strategy for disease remission maintenance by assessing clinical conditions, blood eosinophil count (BEC) and adverse events at baseline and at 3-6-12 months follow-up. Overall, 11 patients were enrolled (females 4-36%) with a median age of 62 years (IQR 55.0-72.0). At 3-month visit both prednisone daily dose and BEC significantly decreased from baseline, whilst a substantial improvement of Brief fatigue inventory score (BFI) was not recorded before the 6 months assessment. More than 70% of patients completely stopped prednisone at 12-months follow-up, without any flare in terms of BEC and BFI. No adverse event was registered. Although larger studies are needed, our report firstly describes that in a well-defined population, diagnosed with I-HES and in disease remission, low dose mepolizumab is a safe and effective steroid-sparing option for remission maintenance. It suggests that a personalized treatment dose might be explored according to the disease classification and activity at the time of biologic treatment start.

Eosinophilic Granulomatosis with Polyangiitis: Latest Findings and Updated Treatment Recommendations

Eosinophilic granulomatosis with polyangiitis (EGPA) causes necrotizing vasculitis and eosinophil-rich granulomatous inflammation in small- to medium-sized vessels, resulting in multiple organ damage. EGPA is classified as an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, with myeloperoxidase-ANCA detected in approximately one-third of the patients. Conventional treatment of EGPA relies on systemic glucocorticoids (GCs) in combination with cyclophosphamide when poor prognostic factors are present; however, the dilemma between disease control and drug-related adverse effects has long been a challenge. Recent studies have revealed that the genetic background, pathophysiology, and clinical manifestations differ between ANCA-positive and ANCA-negative patients; however, mepolizumab, an interleukin (IL)-5 inhibitor, is effective in both groups, suggesting that the IL-5-eosinophil axis is deeply involved in the pathogenesis of both ANCA-positive and ANCA-negative EGPA. This review summarizes the latest knowledge on the pathophysiology of EGPA and focuses on the roles of eosinophils and ANCA. We then introduce the current treatment recommendations and accumulated evidence for mepolizumab on EGPA. Based on current unmet clinical needs, we discuss potential future therapeutic strategies for EGPA.

Clinical features and long-term outcomes of patients with systemic polyarteritis nodosa diagnosed since 2005: Data from 196 patients

BACKGROUND

The landscape of polyarteritis nodosa (PAN) has substantially changed during the last decades. Recent data regarding causes, characteristics, and prognosis of systemic PAN in the modern era are lacking.

METHODS

This retrospective study included patients with systemic PAN referred to the French Vasculitis Study Group between 2005 and 2019. Characteristics, associated conditions and outcomes were collected, and predictors of relapse and death were analyzed.

RESULTS

196 patients were included. Main clinical symptoms were constitutional (84%), neurological (59%), skin (58%) and musculoskeletal (58%) manifestations. Secondary PAN accounted for 55 (28%) patients, including myelodysplastic syndrome (9%), solid cancer (7%), lymphoma (4%) and autoinflammatory diseases (4%). No patient had active HBV infection. All treated patients (98.5%) received glucocorticoids (GCs), alone (41%) or in combination with immunosuppressants (59%), with remission achieved in 90%. Relapses were independently associated with age >65 years (HR 1.85; 95% CI1.12-3.08), gastrointestinal involvement (1.95; 95% CI1.09-3.52) and skin necrotic lesions (HR 1.95; 95%CI 1.24-3.05). One-, 5- and 10-year overall survival rates were 93%, 87% and 81%, respectively. In multivariate analyses, age >65 years (HR 2.80; 95%CI 1.23-6.37), necrotic purpura (HR 4.16; 95%CI 1.62-10.70), acute kidney injury (HR 4.89; 95% 1.71-13.99) and secondary PAN (HR 2.98; 95%CI 1.29-6.85) were independently associated with mortality.

CONCLUSION

Landscape of PAN has changed during the last decades, with the disappearance of HBV-PAN and the emergence of secondary PAN. Relapse rate remains high, especially in aged patients with gastrointestinal and cutaneous necrosis, as well as mortality.

Biologics and Hypereosinophilic Syndromes: Knowledge Gaps and Controversies

Hypereosinophilic syndromes (HES) are a heterogeneous group of disorders defined by blood and/or tissue hypereosinophilia and clinical manifestations attributable to the eosinophilia. Although various clinical subtypes of HES have been described, the general approach to therapy in all subtypes has focused on the reduction of blood and tissue eosinophilia to improve symptoms and halt disease progression. Until recently, this typically involved the use of corticosteroids and/or other immunosuppressive or cytotoxic drugs with significant toxicity. Whereas imatinib, the first targeted therapy approved for treatment of HES, has dramatically changed the prognosis of patients with primary (myeloid) forms of HES, it is ineffective in patients with other HES subtypes. For these nonmyeloid patients with HES, the development of eosinophil-targeting biologics (most notably, mepolizumab, the first biologic approved for the treatment of HES) has been transformative. Nevertheless, important issues remain with respect to the efficacy and safety of these biologics in the treatment of the varied subtypes of HES. Moreover, with the increasing number of commercially available biologics with direct or indirect effects on eosinophils, questions related to the choice of initial biologic, potential reasons for biologic failure, and treatment options in the setting of incomplete response are becoming increasingly common.

A Case of Amoxicillin-Induced Drug Reaction With Eosinophilia and Systemic Symptoms (Dress) Syndrome Associated With Significant Reactive Hypereosinophilia (HE): A Case Report

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome is a severe cutaneous drug reaction characterized by a skin rash, eosinophilia, atypical lymphocytosis, and involvement of multiple organs. The mortality rate of DRESS syndrome is moderate, and prompt diagnosis and treatment are essential. When DRESS syndrome is presented with significant hypereosinophilia (HE), it should be differentiated from other conditions that can cause HE through a comprehensive approach to diagnostic evaluation. Amoxicillin has been well-documented as a potential cause of DRESS syndrome. It is important to note that amoxicillin can trigger DRESS syndrome in patients who already have a known allergy to sulfasalazine, as well as when it is administered with a beta-lactamase inhibitor such as clavulanic acid. Here, we describe a case of amoxicillin alone-induced DRESS syndrome associated with significant reactive HE. A 39-year-old female presented with three days of shortness of breath, fatigue, facial swelling, and a generalized maculopapular skin rash. The patient endorsed taking amoxicillin two to three weeks prior to the presentation. Diagnostic tests revealed HE, significant generalized lymphadenopathy on computed tomography (CT) scans of the neck and abdomen, and bilateral interstitial infiltration on a CT scan of the chest suggestive of eosinophilic infiltration. Based on the European Registry of Severe Cutaneous Adverse Reactions (RegiSCAR) scoring system, the case was categorized as "probable" DRESS syndrome related to amoxicillin. High-dose steroids were initiated as the treatment of choice for suspected DRESS syndrome. Other potential causes of HE were investigated and ruled out. The patient showed significant clinical improvement, with the normalization of absolute eosinophil count (AEC) and complete resolution of lung infiltrates on a repeat CT scan of the chest. The case highlights the importance of conducting a comprehensive diagnostic evaluation to differentiate DRESS syndrome from other causes of HE when significant HE is present. Prompt treatment with high-dose steroids is essential in managing patients with severe symptoms associated with DRESS syndrome. It is crucial to consider amoxicillin as a potential trigger for DRESS syndrome, even when there is no history of sulfasalazine allergy or concurrent administration of a beta-lactamase inhibitor.

False-Negative Testing for FIP1L1::PDGFRA by Fluorescence in situ Hybridization Is a Frequent Cause of Diagnostic Delay

The imatinib-sensitive fusion gene FIP1L1::PDGFRA is the most frequent molecular abnormality identified in patients with eosinophilic myeloid neoplasms. Rapid recognition of this mutation is essential given the poor prognosis of PDGFRA-associated myeloid neoplasms prior to the availability of imatinib therapy. We report a case of a patient in whom delayed diagnosis resulted in cardiac transplantation for eosinophilic endomyocardial fibrosis. The delay in diagnosis was due, in part, to a false-negative result in fluorescence in situ hybridization (FISH) testing for FIP1L1::PDGFRA. To explore this further, we examined our cohort of patients presenting with confirmed or suspected eosinophilic myeloid neoplasms and found 8 additional patients with negative FISH results despite a positive reverse-transcriptase polymerase chain reaction test for FIP1L1::PDGFRA. More importantly, false-negative FISH results delayed the median time to imatinib treatment by 257 days. These data emphasize the importance of empiric imatinib therapy in patients with clinical features suggestive of PDGFRA-associated disease.

Management of eosinophil-associated inflammatory diseases: the importance of a multidisciplinary approach

Elevated eosinophil counts in blood and tissue are a feature of many pathological processes. Eosinophils can migrate and accumulate in a wide variety of tissues and, by infiltrating a target organ, can mediate the development of several inflammatory diseases. The normalization of eosinophilia is a common biomarker of a treatable trait and can also be used as a prognostic and predictive biomarker since it implies a reduction in type 2 inflammation that contributes to disease pathogenesis. Biological therapies targeting this cell type and its proinflammatory mediators have been shown to be effective in the management of a number of eosinophilic diseases, and for this reason they constitute a potential common strategy in the treatment of patients with various multimorbidities that present with type 2 inflammation. Various biological options are available that could be used to simultaneously treat multiple target organs with a single drug, bearing in mind the need to offer personalized treatments under the umbrella of precision medicine in all patients with eosinophil-associated diseases (EADs). In addition to reviewing these issues, we also discuss a series of perspectives addressing the management of EAD patients from a multidisciplinary approach, with the collaboration of health professionals from different specialties who manage the different multimorbidities that frequently occur in these patients. We examine the basic principles of care that this multidisciplinary approach must cover and present a multidisciplinary expert opinion regarding the ideal management of patients with EADs, from diagnosis to therapeutic approach and follow-up.

French guidelines for the etiological workup of eosinophilia and the management of hypereosinophilic syndromes

Eosinophilic-related clinical manifestations are protean and the underlying conditions underpinning eosinophilia are highly diverse. The etiological workup of unexplained eosinophilia/hypereosinophilia can be challenging, and can lead sometimes to extensive, inappropriate, costly and/or invasive investigations. To date, guidelines for the etiological workup and management of eosinophilia are mainly issued by hematologists, and thus mostly cover the scope of clonal hypereosinophilic syndromes (HES). Here, thanks to an extensive literature review, and thanks to the joint work of a large panel of experts involving physicians from both adult and pediatric medicine and from various subspecialties (as well as a representative of a patients' association representative), we provide recommendations for both the step-by step diagnostic workup of eosinophilia (whether unexplained or within specific contexts) as well as the management and follow-up of the full spectrum of eosinophilic disorders (including clonal, reactive, lymphocytic and idiopathic HES, as well as single-organ diseases). Didactic prescription summaries intended to facilitate the prescription of eosinophil-targeted drugs are also provided, as are practical diagnostic and therapeutic algorithms. Lastly, this set of recommendations also includes a summary intended for general practitioners, as well as an overview of the therapeutic patient education program set up by the French reference center for HES. Further updates will be mandatory as new validated information emerges.

[Eosinophilia: hypereosinophilic syndrome vs. eosinophilic granulomatosis with polyangiitis]

Hypereosinophilic syndrome (HES) is defined as a peripheral eosinophil count of > 1500/μl (assessed twice at an interval of ≥ 2 weeks) and an eosinophil-induced organ damage. Idiopathic HES is differentiated from primary (clonal or neoplastic) HES and secondary (reactive) HES, depending on the etiology. Eosinophilic granulomatosis with polyangiitis (EGPA) is categorized as a secondary form of HES and is characterized by hypereosinophilia and vasculitis of small to medium-sized vessels and can be associated with an antineutrophil cytoplasmic antibody (ANCA). The treatment of HES is dependent on the etiology. Clonal HES is treated according to the respective genetic aberration, e.g. with tyrosine kinase inhibitors or chemotherapy and allogenic stem cell transplantation. Secondary forms should be treated according to the underlying cause (e.g. parasitic infection). The treatment of EGPA is carried out with immunosuppressants depending on the disease stage and disease activity. Conventional drugs, such as glucocorticoids (GC), cyclophosphamide (CYC) and methotrexate (MTX) or biologics, such as the monoclonal anti-IL5 antibody mepolizumab are commonly used. Mepolizumab is also a good option for the treatment of idiopathic HES.

A case of complete recovery in a hypereosinophilic dermatitis patient with dupilumab

BACKGROUND

Hypereosinophilic dermatitis (HED) is a subtype of hypereosinophilic syndrome (HES). Glucocorticoids are preferred for treatment but carry substantial side effect profiles. Symptoms of HED may recur after systemic glucocorticoid tapering. As an interleukin-4 receptor (IL-4Rα) monoclonal antibody targeting interleukin-4 (IL-4) and interleukin-13 (IL-13), dupilumab might be an efficacious adjuvant therapy for HED.

METHOD

We report a young male diagnosed with HED who suffered from erythematous papules with pruritus for over five years. Once reducing the dosage of glucocorticoid was, his skin lesions relapsed.

RESULTS

After using dupilumab, the patient's condition significantly improved with the glucocorticoid dosing decreased successfully.

CONCLUSION

In conclusion, we report a new application of dupilumab in HED patients, especially with difficulties in reducing the glucocorticoid dose.

Eosinophilia and elevated IgE serum levels: a red flag: when your diagnosis is not a common atopic eczema or common allergy

OBJECTIVE AND DESIGN

The hallmark of type 2 inflammation is eosinophilia and/or high IgE serum levels, mostly in atopic dermatitis. Nevertheless, many dermatoses may present similar findings. Our aim is to explore the biological and clinical spectrum of cutaneous manifestations involving tissue and/or systemic eosinophilia, and distinct serum levels of IgE, where atopic dermatitis or other primary allergic eczema, not always is the definitive diagnosis.

MATERIALS/METHODS

A total of 37 scientific papers were enrolled in this narrative review.

RESULTS

A diagnostic approach for patients with elevated serum IgE level and a list of conditions not related to atopic dermatitis that runs through inborn errors of immunity, inflammatory disorders, lung disorders, malignancy, infections/infestations are displayed. Regarding to peripheral eosinophilia, differential diagnosis is also explored and clinical patterns of skin diseases associated with tissue eosinophilia are listed, to facilitate our diagnosis.

CONCLUSIONS

We should maintain a high level of suspicion about other differential diagnosis involving eosinophilia and IgE dysregulation, especially in patients very young (when innate errors of the immunity may present) and in middle to elderly patients classified as having atopic dermatitis, due to the possibility of cutaneous hematological malignancies, paraneoplasia or autoimmune blistering diseases.