Eosinophilic Granulomatosis with Polyangiitis, EGPA (Churg–Strauss Syndrome)
EGPA (formerly Churg-Strauss syndrome, allergic angiitis and granulomatosis) is a granulomatous vasculitis of small- and medium-sized vessels, frequently involving the skin, peripheral nerves, and lungs, and is associated with peripheral eosinophilia. EGPA occurs primarily in patients with a previous history of allergic manifestations, such as rhinitis (often with nasal polyps) (70%) and adult-onset asthma (>95%). Cytokines that affect eosinophils (IL-5) and eosinophil granule proteins (major basic protein, cationic protein) appear to be important in the pathogenesis of this disease.
Clinical phases of EGPA:
The prodromal phase averages 28 months but may persist for years (2 to 7 years). It consists of allergic manifestations of rhinitis, polyposis, and most commonly asthma (80% to 90%). Recurrent fevers occur in 50% of cases during this stage.
Peripheral blood and tissue eosinophilia develop, frequently causing a picture resembling Löffler syndrome (shifting pulmonary infiltrates and eosinophilia), chronic eosinophilic pneumonia, or eosinophilic gastroenteritis. Myocarditis can develop. This second phase may remit or recur over years before the third phase. Fever is always present during the flares.
Life-threatening systemic vasculitis occurs on average 3 years after the onset of the prodromal phase. Asthma can abruptly abate as the patient moves into this phase. Patients can develop myocarditis, valvular insufficiency, neurologic symptoms (most commonly vasculitic peripheral neuropathy), eosinophilic gastroenteritis, purpura, and testicular pain.
Major Clinical Features of Eosinophilic Granulomatosis With Polyangiitis:
Acute or chronic paranasal sinus pain or tenderness, rhinitis (70%), polyposis, opacification of paranasal sinuses on radiographs
Asthma (usually adult onset), patchy and shifting pulmonary infiltrates (70%), nodular infiltrates without cavitations, pleural effusions and diffuse interstitial lung disease seen on chest radiograph. Pulmonary hemorrhage can occur.
Nervous system (60-70%)
Mononeuritis multiplex or asymmetric sensorimotor polyneuropathy; rarely CNS or cranial nerve involvement
Subcutaneous nodules, petechiae, purpura, skin infarction (occur mainly during the vasculitic phase)
Arthralgias and arthritis (rare)
Eosinophilic gastroenteritis (abdominal pain, bloody diarrhea), abdominal masses
Renal failure (uncommon), congestive heart failure, corneal ulcerations, panuveitis, prostatitis
The characteristic laboratory abnormality is eosinophilia (>1500 cells/μL). Anemia, elevated ESR/CRP, elevated IgE (70%), and positive rheumatoid factor (70%) may be found. ANCAs are present in 50% to 65% of patients. These are directed primarily against MPO and give a p-ANCA pattern. Patients who are ANCA-positive are more likely to develop renal disease, alveolar hemorrhage, mononeuritis multiplex, and purpura. There is no direct correlation between the degree of eosinophilia and disease activity
The Five Factor Score (FFS) describes five features, associated with poor prognosis in EGPA:
Creatinine >1.58 mg/dL
Proteinuria >1 g/day
The FFS has recently been applied to GPA and MPA but proteinuria has been excluded as a prognostic marker. Using the four remaining FFS indicators, the 5-year survival for patients with any AAV was 91% for FFS of 0, 79% for FFS of 1, and 60% for FFS ≥2.