Small Vessel Vasculitis Research Articles

Lung transplantation for alpha-1-antitrypsin deficiency and Behçet's disease: A case report

INTRODUCTIONAlpha-1-Antitrypsin deficiency (A1ATD) is a genetically determined anti-proteinase deficiency which predisposes to early onset emphysema and liver disease. Lung transplantation (LTx) is the final therapeutic option. Behçet's disease (BD) is a rare autoimmune disease characterized by oral and genital ulcers, deep venous thrombosis associated with large and small-vessel vasculitis and aneurysms. The association of A1ATD and BD is unknown. We aim to describe a rare case of concomitant presentation of these pathologies in a patient submitted to LTx. CASE REPORTA 31-years-old female presented with oral and genital ulcers associated with cavernous sinus thrombosis in 2012, being diagnosed with BD. In 2018 debuted with progressive respiratory symptoms. CT-scan revealed extensive pulmonary emphysema associated with decreased pulmonary function. A1ATD was identified with a heterozygous “MZ” allelic combination. She was referred to LTx center in 2021. After additional investigation, the patient was considered to LTx. She underwent standard bilateral LTx in July of 2022. During post-operative time, special attention was given to the risk of vascular complications, and pos-operative angio-CT was performed actively searching for this possible outcome. Nevertheless, no major events occurred. After 1 year, she is fully functional with no signs of BD activity. CONCLUSIONTo our knowledge, this is the first description of LTx for A1ATD in a patient with BD, proving its feasibility in a highly selected patient at an experienced and specialized center. Nonetheless, solid organ transplantation in patients with BD remains a high risk procedure and should be indicated with caution.

Characteristics associated with anterior ischemic optic neuropathy (AION) in giant cell arteritis (GCA).

Giant cell arteritis (GCA) is the most common vasculitis and can result in blindness due to anterior ischemic optic neuropathy (AION). Little is known about which patients with GCA are at higher risk of AION.We did a retrospective chart review to compare demographics, past medical history, labs and imaging of GCA patients with and without AION. All patients at the University of Washington who were diagnosed with GCA by a rheumatologist, had a vascular ultrasound and met classification criteria for GCA were included. AION was diagnosed by an ophthalmologist. To compare demographics, symptoms, presentation imaging and lab findings, we used Pearson Chi-square, Fisher's exact test and t-tests to compare GCA patients with and without AION. 91 patients with GCA without vision loss were compared to 15 patients with GCA and AION.The AION group had significantly more men (p=0.03) and elevated C-reactive protein (CRP) as compared to the non-AION group (p = 0.04). Rates of hypertension, smoking, erythrocyte sedimentation rate (ESR) and classification scores were similar. Vascular ultrasound showed similar rates of small and large vessel vasculitis, but the AION group had higher halo scores, with the AION group having a mean score of 5 and patients with GCA and without AION having a mean score of 3 (p < 0.01). Older men with GCA and more than three halos on vascular ultrasound imaging of GC may be at higher risk of AION. Key Points • This is the first paper to incorporate the use of vascular ultrasound in comparing patients with anterior ischemic optic neuropathy (AION) to those without giant cell arteritis (GCA). • Male sex is associated with AION despite GCA being more common in women. • Older age and higher CRP are associated with AION. • GCA patients with AION had a higher halo score than GCA patients without AION.

Vasculitis associated with VEXAS syndrome.

To define the prevalence, distribution, and characteristics of patients with VEXAS who have confirmed vasculitis. Patients with VEXAS syndrome, verified by positive UBA1 mutation, were included. Chart review was performed to identify. characteristics and outcomes. Vasculitis diagnosis was based on either histopathology showing vascular inflammation or non-invasive angiography findings. Summary statistics were calculated. Eighty-nine patients met inclusion criteria. All were male with a median age of onset of 66.9 years (IQR 60.1, 72.7). Median (IQR) follow up was 3.8(2.2-5.5) years during which 21 patients (23.6%) had evidence of vasculitis. Vasculitis subtypes included small vessel vasculitis (19.1%), cutaneous medium vessel vasculitis (2.2%), and large vessel vasculitis (2.2%). No patient had more than one vessel size involved. Histopathology in small vessel vasculitis patients was consistent with cutaneous leukocytoclastic vasculitis in the majority, though one patient had leukocytoclastic peritubular capillaritis on renal biopsy. Cranial symptoms (headache, vision changes, or jaw pain) were noted in 18.0%. Two additional patients not experiencing cranial symptoms exhibited large vessel involvement with confirmed carotid thickening on non-invasive angiography; one of these had a positive temporal artery biopsy. VEXAS syndrome manifests as a variable vessel vasculitis in a quarter of patients, with cutaneous small and medium vessel involvement being particularly common. Some patients may have positive ANCA serologies or even renal vasculitis leading to misdiagnosis. Cranial symptoms are common and may mimic giant cell arteritis, though documented large vessel inflammation is rare.

Neuro-Behcet's Masquerading as Status Epilepticus and Meningoencephalitis in the Emergency Department

BackgroundBehcet disease (BD) is a rare small vessel vasculitis that commonly manifests as recurrent painful oral or genital ulcerations, uveitis, and skin lesions. Some patients with BD develop neurological symptoms termed neuro-Behcet's disease. In the emergency department (ED) setting, these symptoms can be mistaken for other common acute issues including stroke, infection, epilepsy, multiple sclerosis, toxin ingestion, or psychiatric conditions. Case ReportWe present a case of a 28-year-old male with neuro-Behcet disease mimicking status epilepticus and meningoencephalitis. He was actively seizing on arrival and febrile at 103.8 F. The patient also had a history of vasculitis, uveitis and genital lesions which raised suspicion for a rheumatological process. Cerebrospinal fluid (CSF) samples were obtained and computed tomography (CT) of the head revealed no acute findings. The patient was started on treatment for seizure and meningoencephalitis and admitted to neurology for continuous electroencephalogram (EEG) monitoring with additional consults placed for rheumatology, ophthalmology, and infectious disease. The patient was ultimately diagnosed with neuro-Behcet's disease and treated appropriately.Why should an emergency physician be aware of this?: In a patient presenting with neurological symptoms and signs of rheumatological disease providers should consider neuro-Behcet's disease as a differential diagnosis. This case exemplifies the vital role of reviewing past medical history to expand differential diagnoses and early coordination with specialists so treatment can be initiated early to prevent morbidity and mortality. The case will also review different presentations of this unfamiliar diagnosis for a more comprehensive understanding.

Letrozole induced Necrotizing Cutaneous Vasculitis: A Rare Entity

Cutaneous small vessel vasculitis (CSVV) could be due to varied etiologies of which drug induced CSVV is a prime cause. It commonly presents as purpura but necrotizing lesions can be an uncommon presentation of the disease. Aromatase inhibitors like letrozole are newer drugs used in the management of breast carcinoma. There have been few reports of drug induced vasculitis secondary to letrozole. Herein, we report a case presenting with multiple purpura with ulcers and hemopurulent discharge over bilateral legs after letrozole intake for breast carcinoma. Patient was diagnosed with necrotizing CSVV due to letrozole based on history and clinico-histopathological correlation. To the best of our knowledge, this is the first report of letrozole induced necrotizing CSVV from India.

A Classical Manifestation of Eosinophilic Granulomatosis with Polyangiitis with an Unusual Catastrophic Outcome

A 57-year-old male patient, with a known case of bronchial asthma presented with acute dyspnea, cough with expectoration, fever, severe myalgia, and pedal edema. On physical examination, he had tachypnea, high temperature, bilateral polyphonic rhonchi, audible wheeze, and asymmetric sensory and motor neuropathy. Cutaneous examination revealed multiple palpable purpuric lesions with few hemorrhagic bullae and crusted erosions distributed symmetrically over bilateral limbs suggestive of cutaneous small vessel vasculitis. Investigations showed elevated total counts, eosinophilia, deranged electrolytes, and abnormal liver and renal function tests. Histopathology revealed eosinophilic predominant vasculitis. Testing for perinuclear anti-cytoplasmic antibody was positive. A diagnosis of eosinophilic granulomatosis with polyangiitis (Churg–Strauss disease) was thus confirmed. The patient succumbed in 2 weeks due to multi-organ failure. All the characteristic findings were found in our patient, but a fatal outcome in a very short period after diagnosis was an unusual presentation.

Fatal outcome in isolated Pauci-immune pulmonary capillaritis: A case report.

Isolated Pauci-immune pulmonary capillaritis (IPIPC) is a rare form of small vessel vasculitis that affects only the lungs, causing inflammation of pulmonary capillaries and potentially leading to severe outcomes like alveolar haemorrhage. A 23-year-old woman with a prior diagnosis of rheumatoid arthritis presented with hemoptysis and respiratory distress, ultimately diagnosed with IPIPC. Despite treatment with high-dose steroids and intravenous immunoglobulin, her condition deteriorated, resulting in respiratory failure and death. IPIPC often lacks systemic symptoms and ANCA positivity, complicating diagnosis and treatment. Imaging, bronchoscopy, and histopathology are key for diagnosis, while management typically involves corticosteroids and possibly immunosuppressives. The case underscores the challenges in identifying and treating IPIPC, highlighting the importance of early intervention to improve prognosis, even though complications can still lead to significant respiratory issues and mortality.

Vasculitic involvement of the skeletal muscle and the peripheral nervous system: clinical and neuropathologic perspective

The peripheral nervous system is a classic target organ in systemic vasculitis. In addition, the skeletal muscle can also be affected. Myalgia, muscle weakness and sensory deficits are typical signs, which can lead to severe functional limitations and impaired of quality of life. Vasculitic involvement of the skeletal muscle (vasculitic myopathy [VM]) and peripheral nerves (vasculitic neuropathy [VN]) occurs predominantly in polyarteritis nodosa and small-vessel vasculitis. VM presents with elevated markers of inflammation and is typically characterized by immobilizing myalgia with normal creatine kinase activity and diffuse or patchy areas of hyperintensity on T2-weighted MRI ("MRI myositis without myositis"). In VN, sensor motor deficits predominantly affect the lower extremity in the area supplied by several peripheral nerves (e.g., mononeuritis multiplex) with acute to subacute history. The histopathological examination of nerve and muscle biopsies is the gold standard for the diagnosis of vasculitic manifestations and has a significant impact on the therapeutic approach.

A unique and rare presentation of Henoch-Schonlein purpura: a case report

Henoch-Schönlein purpura (HSP), or IgA vasculitis, is a common small vessel vasculitis in children, typically presenting with palpable purpura, abdominal pain, arthritis, and renal involvement. However, atypical presentations can delay diagnosis and management. A 12-year-old girl presented with multiple episodes of loose stools and abdominal pain. The initial diagnosis focused on acute gastroenteritis, and she was treated symptomatically. Subsequently, she developed urticarial rashes with breathing difficulty, complicating the diagnosis. Despite symptomatic treatment, she experienced severe abdominal pain, hematemesis and melena. Further investigations revealed antral gastritis, duodenitis, and cystitis. On the 14th day of admission, the patient developed characteristic palpable purpura on the lower limbs. Skin biopsy confirmed leukocytoclastic vasculitis with IgA deposits, consistent with HSP. The patient recovered with supportive care and remained symptom-free on follow-up. This case underscores the importance of considering HSP in pediatric patients with atypical presentations, such as gastrointestinal symptoms and urticaria without initial purpura. Early recognition and appropriate management are essential to prevent complications and ensure favourable outcomes. The variability in HSP presentations necessitates a high index of suspicion for timely diagnosis and treatment.

Adult-Onset IgA Vasculitis Complicated by Kidney Failure at Disease Onset in a Nepalese Patient: A Case Report

Introduction: Immunoglobulin A (IgA) vasculitis, previously known as Henoch-Schönlein purpura, is an immune complex-mediated small vessel vasculitis primarily affecting children. While rare in adults, it can present with more severe manifestations, particularly involving the kidneys. This case report details the presentation and management of adult-onset IgA vasculitis with significant renal involvement.  Case Report: A 43-year-old male with a history of bipolar disorder presented with facial swelling, shortness of breath, and decreased urine output following an upper respiratory infection. Initial investigations revealed elevated blood pressure and renal impairment. Despite supportive treatment, his condition worsened, leading to a referral to a tertiary care center. He exhibited symptoms consistent with IgA vasculitis, including joint pain, rash, and nephrotic-range proteinuria. The diagnosis was confirmed through a skin biopsy and 24-hour urine collection. The patient was treated with intravenous methylprednisolone, oral prednisone, and an ACE inhibitor. His renal function improved with this regimen.  Discussion: Adult-onset IgA vasculitis can present with severe kidney involvement, including nephrotic-range proteinuria and elevated serum creatinine, which are associated with poorer outcomes compared to pediatric cases. The patient's management, involving glucocorticoids and an ACE inhibitor, aligns with current treatment recommendations for significant renal involvement. Long-term prognosis in adults remains challenging, with a higher risk of end-stage kidney disease compared to children. Vigilant monitoring and tailored treatment strategies are crucial for improving outcomes.  Conclusion: This case underscores the potential severity of adult- onset IgA vasculitis and highlights the importance of early diagnosis and aggressive management to mitigate long- term renal complications. Ongoing research is necessary to refine treatment approaches and enhance outcomes for adults with this condition.

Tense blisters and hemorrhagic bullae as the first manifestation of eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) poses a significant diagnostic challenge due to its varied clinical presentation. Here, we present a case of a 59-year-old female with a history of asthma and sinusitis, who manifested with an extremely rare presentation of drastic tense blisters and hemorrhagic bullae alongside purpuric lesions and peripheral neuropathy. Examinations revealed eosinophilia, positive anti-neutrophil cytoplasmic antibody, and characteristic pathological findings with small vessel vasculitis in the purpura. Treatment with glucocorticoids and cyclophosphamide led to rapid improvement in peripheral eosinophilia, skin manifestations and motor neuron deficits. Although rare, our case underscores that bullous skin lesions should be recognized as a potential cutaneous hallmark of EGPA to aid timely diagnosis, since prompt treatment initiation is crucial given the potential irreversible organ damage and poor prognosis of EGPA.

Diagnostics and treatment of urticarial vasculitis associated with COVID-19

Currently, the problem of COVID-19 continues. The possible consequences of acute infection are not entirely clear. Various dermatological manifestations of COVID-19, including urticarial vasculitis (UV), are increasingly being reported. Urticarial vasculitis (UV) is a rare chronic inflammatory disease presenting with long-lasting wheals with or without angioedema [1]. Histopathological, UV is a leukocytoclastic vasculitis, a common form of small vessel vasculitis, including arterioles, capillaries, and postcapillary venules, in which the inflammatory infiltrate consists of neutrophils with fibrinoid necrosis and nuclear disintegration into fragments (“leukocytoclasia”) [1]. We report a case of urticular vasculitis in a 54-year-old woman who does not suffer from systemic diseases, with a burdened allergic anamnesis (drug allergy to levomycetin with a clinic of widespread toxicoderma). For 2 months after discharge, the patient took colchicine at a dosage of 0.5 mg, 1 tablet 2 times a day, which reduced the manifestation of clinical symptoms and achieved remission. According to the results of a comprehensive examination, a previously transferred COVID-19 infection is considered as a likely etiological factor.

Giant Cell Arteritis and Takayasu Arteritis: Are They Similar or Different?

Vasculitis is a group of heterogeneous conditions characterised by inflammation of blood vessels. Based on the predominant size of the affected vessel, vasculitis is classified into small, medium, and large vessel vasculitis (LVV). Giant cell arteritis (GCA) and Takayasu’s arteritis (TAK) are the two major types of LVV. GCA was thought to affect only the external carotid artery and its branches, whereas, TAK was thought to affect the aorta and its major branches. Advances in imaging techniques have led to a better understanding of these conditions. It has become increasingly clear that GCA can involve the aorta and its branches. GCA and TAK have overlapping features like propensity to affect the aorta and its branches, similar histopathology, and similar clinical features. However, there are differences in age, geographic location, genetics, and predominant vascular territory involvement. There are subtle differences in clinical features. Are these conditions different ends of the same spectrum or different conditions with similar features? This review compares and contrasts these two conditions based on epidemiology, genetics, pathology, predominant vascular territory involvement, and any differential response to treatment. Based on current evidence, GCA and TAK seem to be distinct conditions and not different ends of the same spectrum.

Mediastinal fibrosis as a puzzling presentation: A clinical conundrum in rheumatology: A case report

Granulomatosis with polyangiitis (GPA) is a type of small vessel vasculitis, most commonly involving the respiratory tract and kidneys. It can occasionally present with mass-like lesions at various sites, including the brain, orbit, skin, genitals, retroperitoneum, and mediastinum. Presentation with mediastinal fibrosis is rare and less commonly recognized. The current study presents the case of a mediastinal mass causing pulmonary artery compression and subsequent pulmonary hypertension (PH) that required stenting. Despite inconclusive mediastinal biopsy results, the integration of clinical, radiological, and laboratory findings led to the diagnosis of ANCA-associated vasculitis, highlighting the challenges and necessity of a multi-modal diagnostic approach in real-world clinical scenarios. This case underscores the importance of considering ANCA-associated vasculitis as a potential etiology in patients presenting with mediastinal fibrosis. Early recognition and appropriate management are crucial in optimizing outcomes for patients with this rare and challenging manifestation.

Granulomatosis with polyangiitis: clinical characteristics and updates in diagnosis.

Granulomatosis with polyangiitis (GPA) is a rare systemic disease characterized by granulomatous inflammation of the respiratory tract and necrotizing vasculitis of small and medium vessels often associated with the production of anti-neutrophil cytoplasmic antibodies (ANCA) directed mainly against leukocyte proteinase 3 (PR3). Usually, it involves upper airways, lungs, and kidneys, however any organ may be affected. The diagnosis is based on clinical, radiological, and serological findings. Biopsies, although strongly recommended, are not always feasible and often provides non-specific features. ANCA plays a crucial role in the diagnosis of GPA; nevertheless, ANCA detection is not a substitute for biopsy, which plays an important role in suspected cases, particularly when histological confirmation cannot be obtained. Significant advances have been made in classification criteria and phenotyping of the disease, particularly in determining the nuances between PR3-ANCA and myeloperoxidase (MPO)-ANCA vasculitis. This has led to better characterization of patients and the development of targeted treatment in the future. In addition, better identification of cytokine and immunological profiles may result in immuno-phenotyping becoming a new approach to identify patients with ANCA-associated vasculitis (AAV). Due to the chronic relapsing-remitting nature, strict follow-up of GPA is necessary to provide appropriate management. The search for the accurate marker of disease activity and to predict relapse is still ongoing and no predictor has been found to reliably guide therapeutic decision-making.

A Retrospective Study of the Histopathological Spectrum of Erythema Nodosum Leprosum.

There are no recent studies with a focus on the histopathology of erythema nodosum leprosum (ENL). To describe the histopathological spectrum of ENL. Digital records from the pathology department were searched, and 125 slides were included. The histopathologic findings were recorded using a pre-designed proforma. Several patterns were noted with the most common being a superficial and deep, perivascular and peri-appendageal, well-circumscribed dermal infiltrate that was seen in 70 (56.0%) biopsies. Other dermal patterns included a similar but loose infiltrate in 19 (15.2%) biopsies, diffuse dermal involvement in 9 (7.2%), top-heavy in 9 (7.2%), and bottom-heavy infiltrates in 12 (9.6%). Subcutaneous tissue was included in 107 biopsies. Extension of dermal infiltrates to the subcutis was noted in 71 (66.4%) biopsies and predominant involvement of the subcutis was noted in 6 (4.8%) biopsies, with lobular involvement in 60 (56.1%), septal involvement in 3 (2.8%), and septo-lobular involvement in 14 (13.1%). In 30 (28.0%) biopsies, the subcutaneous fat was uninvolved. The infiltrates contained neutrophils and foamy histiocytes in variable proportions, along with lymphocytes and plasma cells. Eosinophils were noted occasionally. Medium and/or small vessel vasculitis was noted in 11 (8.8%) biopsies. Fite-Faraco staining was available for 112 biopsies and revealed mainly fragmented and granular acid-fast bacilli (AFB) in 29 (25%) biopsies. Our study had a retrospective design; we could not compare the lesional age and clinical characteristics of patients with the histological features. ENL is characterized by dermal infiltrates composed of foamy histiocytes and neutrophils in varying proportions arrayed in different dermal patterns. Extension of dermal infiltrates into the subcutis was frequent but absent in some. Predominant or exclusive involvement of the subcutis was rare. Vasculitis was noted in a small minority, while AFB were demonstrated in about a quarter of cases.

Predictors of disease severity, length of hospitalization, and recurrence in inpatients with single-organ cutaneous small vessel vasculitis.

There is a lack of systematic studies on single-organ cutaneous small vessel vasculitis (SOCV). To evaluate prognostic clinical and laboratory parameters, including systemic immune-inflammation biomarkers (SIIB) in SOCV inpatients. This study investigated the clinical and laboratory data of 178 inpatients. Blood tests were performed at baseline. SIIB were assessed based on neutrophil-to-lymphocyte ratio (NLR) and pan-immune-inflammation value (PIV). Univariable and multivariable statistics were performed. Both NLR and PIV were significantly higher in SOCV patients than in healthy controls. However, the SIIB values observed in SOCV patients were as high as those in psoriasis patients. On logistic regression analysis, disease manifestation on the upper extremities strongly predicted the absence of severe disease (OR: 0.31, 95%CI: 0.13 to 0.73; p = 0.0071). Moreover, older age (OR: 2.3, 95%CI: 1.11 to 4.77; p = 0.025) and severe disease (OR: 2.4, 95%CI: 1.16 to 4.94, p = 0.018) were significant independent predictors of longer hospital stay, whereas female sex was an independent protective factor for longer hospitalization (OR: 0.52, 95%CI: 0.28 to 0.96, p = 0.038). Lower serum C3 was a strong independent predictor of disease recurrence (OR: 13.9, 95%CI 3 to 63.4; p = 0.0007). The increase in SIIB observed in patients with SOCV reflects that systemic inflammatory alterations also play a role in SOCV patients. We identified several clinical and laboratory-based independent predictors of SOCV severity, length of hospitalization, and disease recurrence that may aid prognostication of SOCV patients.

Myeloperoxidase-ANCA IgG induces different forms of small vessel vasculitis based on type of synergistic immune stimuli

Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis has diverse patterns of injury including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Necrotizing and crescentic glomerulonephritis (NCGN) occurs in all syndromes and as renal limited vasculitis (RLV). Single dose intravenous ANCA IgG-specific for mouse myeloperoxidase (MPO) causes RLV in mice. Although multiple mouse models have elucidated ANCA-IgG induced necrotizing and crescentic glomerulonephritis (NCGN), pathogenesis of ANCA-induced granulomatosis and vasculitis outside the kidney has not been clarified. To investigate this, we used intravenous MPO-ANCA IgG in the same strain of mice to induce different patterns of lung disease mirroring patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Repeated intravenous MPO-ANCA IgG induced GPA with NCGN, lung capillaritis, arteritis and granulomatosis. Lung leukocyte phenotypes were evaluated by immunohistochemical image analysis and by flow cytometry. ANCA lung capillaritis and microabscesses began within one day and evolved into granulomas in under seven days. Influenza plus single dose MPO-ANCA IgG induced MPA with NCGN, lung capillaritis and arteritis, but no granulomatosis. Allergic airway disease caused by house dust mites or ovalbumin plus single dose intravenous MPO-ANCA IgG induced EGPA with eosinophilic bronchiolitis, NCGN, capillaritis, arteritis, and granulomatosis. Thus, our study shows that the occurrence and pattern of lung lesions are determined by the same ANCA IgG accompanied by different synergistic immune factors.

A Case Report on Granulomatosis with Polyangitis and Diffuse Alveolar Haemorrhage

Granulomatous polyangitis (GPA), formerly known as Wegener’s granulomatosis, is a rare form of small-vessel vasculitis. It has no gender predominance and tends to present between the ages of 40 and 55 years old in more than two-thirds of cases. GPA should be critically considered as a diagnosis when a presentation involves multiple systems, including joint, kidney, and lung. Lifesaving treatment of GPA is based on prompt and aggressive administration of pulse steroids and high doses of cyclophosphamide in repeat intervals.

Eosinophilic granulomatosis with polyangiitis: a review article

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of ANCA-associated vasculitis (AAV) within the group of small vessel vasculitides. It is defined by vasculitis of small and medium-sized vessels with granulomatous inflammation and blood and tissue eosinophilia. Almost all patients have allergic symptoms with bronchial asthma and rhinosinusitis symptoms. Further clinical manifestations vary depending on the localisation, severity, and type of disease manifestation. Eosinophilic infiltration and inflammation may result in rhinosinusitis, pneumonitis, gastrointestinal involvement, and cardiomyopathy. The latter, in particular, is associated with a poorer prognosis. As a necrotising pauci-immune small-vessel vasculitis, EGPA, similar to the other AAVs, can cause pulmonary infiltrates with alveolar haemorrhage, glomerulonephritis, cutaneous vasculitis with purpura as well as central and peripheral neurologic injuries. The presence of perinuclear ANCA (pANCA) with specificity against myeloperoxidase (MPO) is observed in approximately one-third of patients but is not specific to EGPA. MPO-ANCA-positive patients are more likely to have peripheral neurologic involvement and glomerulonephritis, whereas ANCA-negative patients are more likely to have cardiac and pulmonary involvement. What is frequently challenging in the clinical routine is to differentiate EGPA from the hypereosinophilic syndrome (HES). The therapeutic approach to EGPA depends on whether the severity of the disease is potentially organ or life-threatening. For severe forms of EGPA, acute therapy mainly includes glucocorticoids in combination with cyclophosphamide. Rituximab has come to be mentioned as an alternative treatment option in the guidelines. Various immunosuppressive therapies are available for remission maintenance. In EGPA without severe organ involvement, IL-5 blockade with mepolizumab is an approved treatment.