Mepolizumab incompletely suppresses clinical flares in a pilot study of episodic angioedema with eosinophilia.

BACKGROUND: Episodic angioedema with eosinophilia (EAE) is a rare multilineage cyclic syndrome of unknown etiology characterized by episodes of angioedema, myalgia, fatigue, and fever that occur every 3 to 8 weeks and resolve between episodes without therapy. Cyclic elevations in serum IL-5 levels and neutrophils precede the increase in absolute eosinophil count (AEC) in most patients. OBJECTIVE: We sought to assess the role of IL-5-driven eosinophilia in the clinical manifestations of EAE. METHODS: An open-label pilot study of mepolizumab (700 mg intravenously monthly for 3 months followed by sequential dose reduction to the Food and Drug Administration-approved dose of 300 mg subcutaneously monthly) was conducted. The primary end point was reduction in the number and severity of clinical symptoms as assessed by patient-reported symptom questionnaires. Secondary end points were greater than or equal to 75% reduction in peak AEC after 1 dose of mepolizumab and sustained reduction in AEC after 3 doses of mepolizumab. Exploratory end points included effects of mepolizumab treatment on other cell lineages (numbers and surface marker expression), levels of plasma mediators, and biomarkers of eosinophil activation. RESULTS: Four female and 1 male (median age, 45 years) participants with EAE were enrolled. None of the 5 participants experienced a reduction in the number of symptomatic flares on mepolizumab therapy, and 1 participant withdrew before study completion because of lack of improvement. Peak AEC was reduced by 75% or more in 3 participants after the first dose of mepolizumab and in 4 participants after 3 doses. CONCLUSIONS: In a small cohort of participants with EAE, mepolizumab was unsuccessful in substantially reducing clinical symptoms despite reduction in AEC.

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.

Possible Association of CD3+CD4-CD8- Phenotype of T-Cell Lymphoma with Peripheral Blood Eosinophilia.

INTRODUCTION: Because the prognosis of patients with peripheral T-cell lymphoma is poor compared to that of patients with B-cell lymphoma, we want to avoid further organ damage by eosinophilia. Moreover, in patients with some types of lymphoma, blood eosinophilia is implicated in a worse prognosis. To study the risk factors of eosinophilia, the association between lymphoma type, immunophenotypic features, and peripheral blood eosinophil counts were examined in the patients with mature T-cell lymphoma. METHODS: We retrospectively examined 28 patients with mature T-cell lymphoma who were admitted to our hospital and whose immunophenotypic features were confirmed using flow cytometric, immunohistochemical analysis, or both between December 2012 and November 2023. RESULTS: We report a possible association between peripheral eosinophilia and peripheral T-cell lymphoma - not otherwise specified and CD3+CD4-D8- (double-negative) phenotypes. Mild eosinophilia was observed in various types, but moderate and severe eosinophilia were observed in patients with peripheral T-cell lymphoma - not otherwise specified. Double-negative phenotype was rarely observed; however, all patients with double-negative phenotype exhibited peripheral blood eosinophilia. In addition, four of the five cases of the double-negative type were peripheral T-cell lymphoma - not otherwise specified. CONCLUSION: Here, we retrospectively examined patients with peripheral T-cell lymphoma whose immunophenotypic features were confirmed and report a possible association between peripheral eosinophilia and peripheral T-cell lymphoma - not otherwise specified and CD3+CD4-CD8- (double-negative) phenotypes. In addition, clinicians should be aware of the possible risk that patients with lymphocytic hypereosinophilic syndrome of the double-negative phenotype may develop peripheral T-cell lymphoma.

Eosinophil-associated diseases: the Allergist's and Clinical Immunologist's perspective.

Summary: Eosinophil-associated diseases (EADs) refer to heterogeneous conditions in which eosinophils are believed to play critical pathological roles. They encompass common respiratory conditions, such as asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), less common primary eosinophilic disorders of gastrointestinal tract, and rare conditions including eosinophilic granulomatosis with polyangiitis (EGPA) and hypereosinophilic syndrome (HES). A literature search was carried out in January 2024 in the MEDLINE and Scopus databases using the PubMed search engine (PubMed, National Library of Medicine, Bethesda, MD). We focused on blood eosinophilia and hypereosinophilia. A diagnostic workup is proposed. From allergist's point of view, we focused the review on 4 groups of eosinophilic disorders of specific interest. Our increased understanding of type 2 inflammation and biology has recently led to development of highly effective precision targeted therapies that are now approved for a growing number of eosinophilic disorders. Novel targeted biologics have a major impact on treatment strategies and have resulted in major advances in our understanding of the pathogenesis of these disorders. In the context of EADs, according to the heterogeneity of eosinophilic disorders a multidisciplinary approach should be adopted. Allergists and Clinical Immunologists play an important role as they have a clear understanding of the eosinophilic inflammation and the role of cytokines and are trained to recognize and characterize type 2 (T2) inflammation and its associated pathologies.

Unmet needs and evidence gaps in hypereosinophilic syndrome and eosinophilic granulomatosis with polyangiitis.

Hypereosinophilic syndrome (HES) and eosinophilic granulomatosis with polyangiitis (EGPA) are rare systemic inflammatory disorders with overlapping symptoms, elevated eosinophil counts, and heterogenous clinical presentations. Although progress has been made in recent years, there are substantial gaps in our understanding of the pathologic mechanisms involved in these diseases, as well as numerous unmet needs relating to both diagnosis and patient management. For example, in most cases of HES, the underlying cause of hypereosinophilia is unknown, while in EGPA, although a polygenic genetic susceptibility has been found, understanding of the pathogenic mechanisms remains largely elusive. Delineating differences between certain disease variants may be challenging, and there are no reliable predictive markers of disease course. In addition, the current diagnostic criteria for HES and classification criteria for EGPA are not easy to implement in a nonspecialist setting, and specialist referral pathways need to be signposted more clearly. Furthermore, disease-specific activity scores need to be developed to aid the assessment of treatment effects, and improved biomarkers are needed to aid with treatment stratification. In this review, we outline the limitations of our current understanding of HES and EGPA and highlight areas for future work, which ultimately should help improve patient management and outcomes.

The challenge of diagnosing and classifying eosinophilia and eosinophil disorders: A review.

Eosinophilia is a feature of multiple conditions, both hematologic and non-hematologic, and may be associated with organ damage. The pathogenesis of eosinophilia can follow two distinct pathways. Primary eosinophilia is caused by a cell-intrinsic mechanism originating from clonal expansion of eosinophils through acquisition of a somatic mutation, such as FIP1L1-PDGFRA. In recent years, great progress has been made in the field of pathogenesis and molecularly targeted therapy of neoplastic eosinophilia. The diagnostic procedure should include, among other things, morphologic analysis of blood and bone marrow samples, cytogenetics and fluorescence in situ-hybridization tests to detect evidence of an acute or chronic myeloid or lymphoid disorder. Secondary eosinophilia follows a cell-extrinsic mechanism as a response to exogenous cytokines. In most clinical cases, peripheral blood eosinophilia is reactive and typically associated with non-hematological disorders such as infections, allergic conditions, connective tissue disorders, vasculitis, malignancy, or endocrinopathies. Nonetheless, the cause of most cases of hypereosinophilic syndrome remains unknown. In this article, we present a short review focused on differential diagnosis of eosinophilia and eosinophilic disorders. The diagnosis of eosinophilia is a challenge for physicians; thus this review may be useful in clinical practice.

JAK inhibition for CD3- CD4+ lymphocytic-variant hypereosinophilic syndrome.

Alternatives are urgently needed in patients with CD3- CD4+ lymphocytic-variant hypereosinophilic syndrome (L-HES) requiring high-level steroids or who are unresponsive and/or intolerant to conventional alternative therapies. We report five L-HES patients (44-66 years) with cutaneous involvement (n = 5) and persistent eosinophilia (n = 3) despite conventional therapies, who successfully received JAK inhibitors (tofacitinib n = 1, ruxolitinib n = 4). JAKi led to complete clinical remission in the first 3 months in all (with prednisone withdrawal in four). Absolute eosinophil counts normalized in cases receiving ruxolitinib, while reduction was partial under tofacitinib. After switch from tofacitinib to ruxolitinib, complete clinical response persisted despite prednisone withdrawal. The clone size remained stable in all patients. After 3-13 months of follow-up, no adverse event was reported. Prospective clinical trials are warranted to examine the use of JAKi in L-HES.

Mitral and Tricuspid Annular Abnormalities in Hypereosinophilic Syndrome-Insights from the Three-Dimensional Speckle-Tracking Echocardiographic MAGYAR-Path Study.

Background: Hypereosinophilic syndrome (HES) is a peripheral eosinophilia characterized by elevated absolute eosinophil cell count ( > 1.500 cells/ µ L) and consequent tissue and end-organ damage. Our aim was to evaluate the mitral annular (MA) and/or tricuspid annular (TA) parameters of patients with HES and to determine whether there are any changes in these parameters compared to healthy individuals. Methods: 17 patients with HES were involved in our study, 2 cases were excluded due to suboptimal image quality (mean age of the evaluated patients: 61.7 ± 11.2 years, 10 males). Their data were compared with those of 24 healthy subjects (mean age: 55.2 ± 7.9 years, 12 males) in the control group. Complete echocardiographic examinations were performed including two-dimensional (2D) Doppler echocardiography and three-dimensional echocardiography (3DE) to assess the MA and the TA. Results: Comparing the echocardiographic parameters of the HES patients with those of the healthy volunteers, the following changes were seen: the interventricular septum was significantly thickened in HES patients, no other significant changes were detected between the examined patient groups. End-diastolic and end-systolic MA diameters, areas and perimeters were increased and MA fractional area change and MA fractional shortening were decreased in HES patients. From TA morphological parameters, only end-diastolic TA area and end-systolic TA perimeter were significantly increased in HES patients. Functional TA parameters showed no significant alterations in the HES group. In patients with HES, no correlations could be detected between 2D and 3D echocardiographic data with the examined laboratory findings. Conclusions: The extent of the dilation of the MA is more pronounced than that of the TA in HES. MA functional impairment is present in HES.

Urine eosinophil-derived neurotoxin: A potential marker of activity in select eosinophilic disorders.

BACKGROUND: Biomarkers of eosinophilic disease activity, especially in the context of novel therapies that reduce blood eosinophil counts, are an unmet need. Absolute eosinophil count (AEC) does not accurately reflect tissue eosinophilia or eosinophil activation. Therefore, the aims of this study were to compare the reliability of plasma and urine eosinophil major basic protein 1, eosinophil cationic protein, eosinophil-derived neurotoxin (EDN), and eosinophil peroxidase measurement and to evaluate the usefulness of eosinophil granule protein (EGP) measurement for the assessment of disease activity in patients with eosinophil-associated diseases treated with mepolizumab, benralizumab, or dexpramipexole. METHODS: Eosinophil granule protein concentrations were measured in serum, plasma, and urine from healthy volunteers and patients with hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), and eosinophilic asthma using a multiplex assay. RESULTS: Urine EGP concentrations remained stable, whereas serum and plasma EGP concentrations increased significantly with delayed processing. Plasma (p) EDN, but not urine (u) EDN, concentration correlated with AEC and negatively correlated with prednisone dose. Both pEDN and uEDN decreased significantly following treatment of HES patients with benralizumab and EGPA patients with mepolizumab. uEDN appeared to increase with clinical relapse in both patient groups. CONCLUSIONS: Measurement of EGP in urine is noninvasive and unaffected by cellular lysis. Although plasma and urine EDN concentrations showed a similar pattern following benralizumab and mepolizumab treatment, the lack of correlation between AEC or prednisone dose and uEDN concentrations suggests that measurement of uEDN may provide a potential biomarker of disease activity in patients with HES and EGPA.

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

Eosinophilia and eosinophil activation are recurrent features in various reactive states and certain hematologic malignancies. In patients with hypereosinophilia (HE), HE-induced organ damage is often encountered and may lead to the diagnosis of a hypereosinophilic syndrome (HES). A number of known mechanisms and etiologies contribute to the development of HE and HES. Based on these etiologies and the origin of eosinophils, HE and HES are divided into primary forms where eosinophils are clonal cells, reactive forms where an underlying reactive or neoplastic condition is detected and eosinophils are considered to be "non-clonal" cells, and idiopathic HE and HES in which neither a clonal nor a reactive underlying pathology is detected. Since 2012, this classification and the related criteria have been widely accepted and regarded as standard. However, during the past few years, new developments in the field and an increasing number of markers and targets have created a need to update these criteria and the classification of HE and HES. To address this challenge, a Working Conference on eosinophil disorders was organized in 2021. In this conference, a panel of experts representing the relevant fields, including allergy, dermatology, hematology, immunology, laboratory medicine, and pathology, met and discussed new markers and concepts as well as refinements in definitions, criteria and classifications of HE and HES. The outcomes of this conference are presented in this article and should assist in the diagnosis and management of patients with HE and HES in daily practice and in the preparation and conduct of clinical trials.

Abnormal T-cell phenotype in episodic angioedema with hypereosinophilia (Gleich syndrome): Frequency, clinical implication, and prognosis.

BACKGROUND: Episodic angioedema with eosinophilia (EAE) (Gleich syndrome) is a rare disorder consisting of recurrent episodes of angioedema, hypereosinophilia, and frequent elevated serum IgM level. METHODS: We conducted a retrospective multicenter nationwide study regarding the clinical spectrum and therapeutic management of patients with EAE in France. RESULTS: A total of 30 patients with a median age at diagnosis of 41 years (range, 5-84) were included. The median duration of each crisis was 5.5 days (range, 1-90), with swelling affecting mainly the face and the upper limbs. Total serum IgM levels were increased in 20 patients (67%). Abnormal T-cell immunophenotypes were detected in 12 patients (40%), of whom 5 (17%) showed evidence of clonal T-cell receptor gamma locus gene (TRG) rearrangement. The median duration of follow-up was 53 months (range, 31-99). The presence of an abnormal T-cell population was the sole factor associated with a shorter time to flare (hazard ratio, 4.15; 95% confidence interval, 1.18-14.66; P = .02). At last follow-up, 3 patients (10%) were able to have all treatments withdrawn and 11 (37%) were in clinical and biologic remission with less than 10 mg of prednisone daily. CONCLUSION: EAE is a heterogeneous condition that encompasses several disease forms. Although patients usually respond well to glucocorticoids, those with evidence of abnormal T-cell phenotype have a shorter time to flare.

Clinical and histopathological features of hypereosinophilic syndrome with cutaneous involvement: The Mayo Clinic Experience.

BACKGROUND: Hypereosinophilic syndrome (HES) encompasses a group of diseases with blood hypereosinophilia and eosinophil-mediated organ dysfunction. HES-associated skin abnormalities, termed cutaneous HES (cHES) here, may influence diagnosis of HES. We sought to better define clinical and histopathological features of cHES. METHODS: We retrospectively reviewed clinical records and cutaneous histopathology of adult patients with HES evaluated at our institution from 2007 to 2018. RESULTS: Forty-one percent (61/150) patients with HES had cHES. The most common clinical morphologies were urticarial (30%) and eczematous (26%). Skin specimens most often showed a spongiotic pattern (31%) with abundant inflammation (50%) including eosinophils (85%). Two specimens (8%) showed interstitial granulomatous dermatitis, and two specimens showed eosinophilic fasciitis (8%). Vasculitis was not identified in any specimen. Eighty-four percent of patients with cHES had ≥1 other organ system involved: pulmonary 41%, ENT 26%, and nervous 23%. Sixty percent (53/89) of non-cHES patients had at least two organ systems involved. Cardiac or gastrointestinal involvement was more common in non-cHES than cHES (p < 0.05). CONCLUSION: Our review confirms that there are no specific clinical or histopathological cHES patterns, but HES should be considered in patients who have eczematous or urticarial reactions of unknown etiology and persistent peripheral hypereosinophilia.

An algorithm-based approach to ascertain patients with rare diseases in electronic health records using hypereosinophilic syndrome as an example.

PURPOSE: Improved hypereosinophilic syndrome (HES) ascertainment in electronic health record (EHR) databases may improve disease understanding and management. An algorithm to ascertain and characterize this rare condition was therefore developed and validated. METHODS: Using the UK clinical practice research datalink (CPRD)-Aurum database linked to the hospital episode statistics database (Admitted Patient Care data) from Jan 2012 to June 2019, this cross-sectional study ascertained patients with a specific HES code (index). Patients with HES were matched (age, sex and index date) 1:29 with a non-HES cohort. An algorithm was developed by identifying pre-defined variables differing between cohorts; model-fitting using Firth logistic regression and statistical determination of the top-five performing models; and internal validation using Leave-One-Out Cross Validation. Final model sensitivity and specificity were determined at an 80% probability threshold. RESULTS: The HES and non-HES cohorts included 88 and 2552 patients, respectively; 270 models with four variables each (treatment used for HES, asthma code, white blood cell condition code, and blood eosinophil count [BEC] code) plus age and sex variables were tested. Of the top five models, the sensitivity model performed best (sensitivity, 69% [95% CI: 59%, 79%]; specificity, >99%). The strongest predictors of HES versus non-HES cases (odds >1000 times greater) were an ICD-10 code for white blood cell disorders and a BEC ≥1500 cells/µL in the 24 months pre-index. CONCLUSIONS: Using a combination of medical codes, prescribed treatments data and laboratory results, the algorithm can help ascertain patients with HES from EHR databases; this approach may be useful for other rare diseases.

Pediatric hypereosinophilic syndrome associated with liver damage, portal vein, splenic vein and superior mesenteric vein thromboses: a case report.

BACKGROUND: The hypereosinophilic syndrome (HES) is a group of rare blood disorders characterized by persistent eosinophilia and damage to multiple organs. HES can be either primary, secondary or idiopathic. Secondary HES are commonly caused by parasitic infections, allergic reactions or cancer. We described a pediatric case of HES associated with liver damage and multiple thrombi. A 12-year-old boy with eosinophilia was complicated with severe thrombocytopenia, liver damage, portal vein, splenic vein, and superior mesenteric vein thromboses. The thrombi recanalized after treatment with methylprednisolone succinate and low molecular weight heparin. No side effects appeared after 1-month. CONCLUSIONS: Corticosteroids should be used at an early stage of HES to prevent further damage to vital organs. Anticoagulants should be recommended only in cases with thrombosis which should be actively screened as a part of evaluation of end organ damage.

Hypereosinophilic syndrome with cutaneous manifestations successfully treated with Dupilumab as a sole agent: A case report.

Hypereosinophilic syndrome describes a process in which eosinophils in the peripheral blood are persistently increased, with variable clinical manifestations. Finding efficacious treatments for this disease can be challenging. This case describes a 72-year-old man with idiopathic hypereosinophilic syndrome with cutaneous manifestations who was successfully treated with dupilumab as a single agent therapy. There was complete clinical and biochemical resolution of disease (eosinophils levels decreased from 4.13 to 0.92) without complications.

[Eosinophilia: hypereosinophilic syndrome vs. eosinophilic granulomatosis with polyangiitis]. / Eosinophilie: hypereosinophiles Syndrom versus eosinophile Granulomatose mit 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.

Pharmacological profile of mepolizumab.

An elevated number of eosinophils have been implicated in several type 2 inflammatory chronic diseases that occur at various sites in the body. Over the past 20 years, our knowledge of diseases associated with increased numbers of eosinophils has advanced thanks to the development of drugs that can reduce or even eliminate eosinophils. One such agent is mepolizumab, a humanized monoclonal antibody that binds to interleukin -5 (IL-5). This article briefly and clearly summarizes the pharmacological profile of mepolizumab and its current indications for a number of chronic eosinophilic diseases.

What we have learned about lymphocytic variant hypereosinophilic syndrome: A systematic literature review.

Lymphocytic variant is a rare subtype of hypereosinophilic syndrome (L-HES) secondary to overproduction of eosinophilopoietic cytokines by the underlying clonal T lymphocytes with abnormal immunophenotypes. Clinical profiles, treatment responses, and outcomes of L-HES are not well characterized given its rarity. We performed a systematic literature review to summarize cases identified in PubMed and Embase databases between January 1994 and July 2021. A total of 148 patients met the inclusion criteria with a median age at diagnosis of 46 years and 51.4% being male. Cutaneous manifestations (81.1%) predominated the clinical picture, while the characteristic cardiovascular involvement was seen in 11.5% of cases. The median eosinophil count at baseline was 5.3 × 109/L and 109 patients (73.6%) had underlying clonal T lymphocytes harboring the classic CD3-CD4+ immunophenotype, which was associated with higher numbers of eosinophils and organ involvement at baseline. Corticosteroids were the most common first-line agent (88.1%), but most patients required additional treatment, leading to clinical or hematologic response in two-thirds. The 10-year overall survival was 81.6% (95% confidence interval [CI] 68.1-89.8). Transformation into malignant T cell lymphoma was observed in 19 patients, specifically in those with cardiovascular involvement (odds ratio [OR] 4.723, 95% CI 1.304-17.108, p = 0.018) and imatinib use (OR 4.284, 95% CI 1.191-15.404, p = 0.026). Taken together, a heavier disease burden was shown in L-HES patients with classic CD3-CD4+ lymphocytes but they were manageable with corticosteroids and sparing agents. There is an increased risk of lymphoma transformation that could be associated with certain clinical surrogates.

Imaging patterns of cerebral ischemia in hypereosinophilic syndrome: case report and systematic review.

INTRODUCTION: Ischemic stroke is a potential complication of hypereosinophilic syndromes (HES), and little is known about underlying pathophysiological mechanisms. We aimed to describe the imaging patterns of cerebral ischemia in patients with HES. METHODS: An individual case is reported. A systematic PubMed review of all records reporting adult patients with HES who suffered ischemic stroke and for whom neuroimaging details of ischemic lesions were available was performed. RESULTS: A 60-year-old man presented with progressive subacute gait difficulty and psychomotor slowing as well as an absolute eosinophilia (2.2 × 109/L) at admission. Brain magnetic resonance tomography revealed multiple acute and subacute internal and external border zone infarcts. Cardiac diagnostic suggested the presence of endomyocarditis. After extensive diagnostic workup, idiopathic HES was diagnosed. The systematic review yielded 183 studies, of which 40 fulfilled the inclusion criteria: a total of 64 patients (31.3% female), with mean age 51.1 years and a median absolute eosinophile count at diagnosis of 10.2 × 109/L were included in the analyses. A border zone pattern of cerebral ischemic lesions was reported in 41 patients (64.1%). Isolated peripheral infarcts were reported in 7 patients (10.9%). Sixteen patients had multiple acute infarcts with no border zone distribution (25.0%). An intracardiac thrombus was reported in 15/60 patients (25%), and findings suggestive of endomyocarditis or endomyocardial fibrosis were found in 31/60 patients (51.7%). CONCLUSIONS: Border zone distribution of cerebral ischemia without hemodynamic compromise is the most frequent imaging pattern in patients with HES, occurring in 2/3 of patients who develop ischemic stroke.

Tumefactive eosinophil-rich non-granulomatous small vessel vasculitis in the cerebrum in a patient with idiopathic hypereosinophilic syndrome.

The definite diagnosis of central nervous system vasculitis requires pathological verification by biopsy or surgical resection of the lesion, which may not always be feasible. A 74-year-old woman with a history of allergic rhinitis, but not asthma, presented with slowly progressive left hemiparesis. Magnetic resonance imaging of the head revealed a heterogeneously enhancing mass involving the right internal capsule and corona radiata. Histological examination of the resected specimen revealed eosinophil-rich non-granulomatous small vessel vasculitis with no neutrophil infiltration or foci of microbial infection. Epstein-Barr virus in situ hybridization was negative, and polymerase chain reaction tests for both T-cell receptor gamma and immunoglobulin heavy-chain variable region genes did not show rearrangements, excluding the possibility of lymphoma and lymphoproliferative disorders. Blood hypereosinophilia and elevated erythrocyte sedimentation rate were observed; however, anti-neutrophil cytoplasmic antibodies were not detected. A biopsy of the erythema in the hips and thighs revealed perivasculitis with eosinophilic infiltration within the dermis. Chest computed tomography revealed multiple small nodules in the lungs. Her symptoms, aside from hemiparesis, disappeared after corticosteroid administration. The clinicopathological features were similar to eosinophilic granulomatosis with polyangiitis but did not meet its current classification criteria and definition. This patient is the first reported case of idiopathic eosinophilic vasculitis or idiopathic hypereosinophilic syndrome-associated vasculitis affecting the small vessels in the brain. Further clinicopathological studies enrolling similar cases are necessary to establish the disease concept and unravel the underlying pathogenesis.