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Eosinophilic granulomatosis with polyangiitis
Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as Churg-Strauss syndrome, is a systemic vasculitis of small-to medium vessels, characterized by asthma, transient pulmonary infiltrates, and hypereosinophilia.
ORPHA:183Classification level: Disorder
- Churg-Strauss syndrome
- Granulomatous allergic angiitis
- Prevalence: 1-9 / 100 000
- Inheritance: Not applicable
- Age of onset: Adolescent, Adult, Elderly
- ICD-10: M30.1
- OMIM: -
- UMLS: C0008728
- MeSH: C531653 D015267
- GARD: 6111
- MedDRA: 10048594
The prevalence ranges from 1/100,000 to 1/70,000 in Europe. It is much more frequent in asthmatic patients (around 1/15,000).
Onset usually occurs between 15 and 70 years of age. EGPA may involve multiple organ systems and patients often have an atopic background. The onset of EGPA is often associated with worsening of the asthma. Allergy and angiitis are the two hallmarks of the disease. EGPA has been divided into three distinct phases, which may or may not be sequential. The prodromal phase is characterized by asthma with or without allergic rhinitis. The second phase is marked by peripheral blood eosinophilia and eosinophilic tissue infiltration producing a picture similar to those of simple pulmonary eosinophilia (Loefflers syndrome), chronic eosinophilic pneumonia, or eosinophilic gastroenteritis (see these terms). The third, vasculitic phase usually develops within 3 years of onset and may involve any of the following organs: heart (myocarditis, pericarditis, failure), peripheral nervous system (mononeuritis multiplexa in 78% of patients), kidney, lymph nodes, paranasal sinuses, muscles, and skin. Skin involvement (nodules, utricarial rash) occurs in two thirds of patients. Fever, flu like symptoms, and weight loss are also observed. Anti-myeloperoxidase (MPO)-anti neutrophil cytoplasmic (ANCA)-positive EGPA patients show a somewhat different clinical phenotype (e.g a higher prevalence of renal disease).
Although the exact etiology of EGPA is unknown, the prominence of allergic features and the presence of immune complexes, heightened T-cell immunity, and altered humoral immunity indicate that the syndrome may represent an autoimmune disorder. In around 40% of patients, EGPA is associated with antineutrophil cytoplasmic antibodies, particularly perinuclear-ANCA/MPO-ANCA. Leukotriene receptor antagonists have been associated with the onset of EGPA, but a causative role in the induction of the disease has not yet been clearly demonstrated.
EGPA can be diagnosed if in addition to the signs of vasculitis, four of the following six features are present: asthma, eosinophilia, neuropathy, pulmonary infiltrates, paranasal sinus abnormalities and eosinophilic vasculitis. Eosinophilia above 10% is the hallmark laboratory finding in patients with EGPA and may be as high as 75% of the peripheral blood cell count. Findings in chest X-ray (infiltrates, pneumonitis) are extremely common in EGPA. Tissue biopsies show eosinophilia, necrotizing vasculitis of small-to medium vessels and sometimes small necrotizing granulomatous inflammation.
Differential diagnoses of EGPA include granulomatosis with polyangiitis (formerly Wegener granulomatosis), hypereosinophilic syndrome, microscopic polyangiitis, cryoglobulinemia (see these terms), drug reactions, bronchocentric granulomatosis, fungal and parasitic infections, and malignancy.
Management and treatment
The treatment of patients with mild disease involves glucocorticoid (GC) monotherapy. Other immunosuppressive regimens, such as those using cyclophosphamide (CP), are used for patients with an aggressive disease. Treatment with interferon-alpha has been effective in patients refractory to GC plus CP. Infliximab is used for steroid dependent patients. Treatment with the anti-interleukin-5 antibody mepolizumab might be effective in treating refractory EGPA and is under trial.
Cardiac involvement is the leading cause of death related to EGPA, followed by cerebral hemorrhage and stroke. Despite treatment, neurological sequelae rarely resolve completely.