Pulmonary ANCA-Associated Vasculitis: Statement Analysis
Statement (b) is correct: Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis) typically shows peripheral blood eosinophilia >10%. 1
Detailed Analysis of Each Statement
Statement (a): EGPA onset precedes asthma exacerbation - FALSE
- Asthma precedes EGPA, not the reverse. The disease classically evolves through three sequential phases: first the allergic phase (distinguished by asthma, allergic rhinitis, and sinusitis), then the eosinophilic phase (with organ infiltrations), and finally the vasculitic phase (with purpura, neuropathy, and constitutional symptoms). 2
- Asthma is present in >90% of EGPA patients and typically begins in adulthood, progressively worsening before other vasculitic manifestations appear. 3
- The statement reverses the actual temporal relationship—asthma is a prodromic feature that precedes the development of systemic vasculitis, not something that worsens after EGPA onset. 4
Statement (b): Eosinophilia >10% in Churg-Strauss syndrome - TRUE
- The 1990 ACR classification criteria explicitly include eosinophilia >10% as one of six diagnostic criteria for EGPA. When four or more criteria are met, vasculitis can be classified as EGPA with 85% sensitivity and 99.7% specificity. 1
- Marked peripheral blood eosinophilia is a characteristic laboratory finding and defining feature of EGPA. 3
- The eosinophilic phase of disease is specifically marked by peripheral eosinophilia and eosinophilic organ infiltrations. 2
Statement (c): Exophthalmos raises suspicion for Wegener's granulomatosis - FALSE
- Ocular manifestations in GPA (Wegener's) typically include scleritis, not exophthalmos. 5, 3
- Scleritis and other ocular manifestations are more common in GPA than in EGPA, but exophthalmos (proptosis) is not a characteristic feature of GPA. 3
- Exophthalmos would more appropriately raise suspicion for orbital pseudotumor, thyroid eye disease, or other orbital inflammatory conditions rather than GPA.
Statement (d): Wegener's limited to lower airways - FALSE
- This statement is completely backwards. Upper respiratory tract disease is a hallmark of GPA, occurring in 85-100% of patients. 3
- Nasal crusting, stuffiness, epistaxis, chronic rhinosinusitis with possible nasal polyps, and nasal septal perforation are common presenting symptoms of GPA. 5
- Persistent sinus pain, congestion, and epistaxis occur in >90% of patients with GPA, making upper airway involvement a key diagnostic clue. 5
- Both upper and lower respiratory tract involvement occur in GPA—the disease does not spare the upper airways. 5
Statement (e): c-ANCA positive in EGPA - FALSE
- EGPA is typically associated with p-ANCA/MPO-ANCA, not c-ANCA. ANCA positivity is detectable in only 30-40% of EGPA patients, and most of these test positive for p-ANCA and MPO-ANCA, not c-ANCA. 1
- In contrast, PR3-ANCA (c-ANCA) positivity is detected in 80-90% of GPA patients and is highly specific for GPA, not EGPA. 5, 3
- The 2022 ACR-EULAR classification criteria for EGPA actually assign negative points (-3) for c-ANCA pattern or PR3-ANCA positivity, as this makes EGPA less likely and GPA more likely. 1
- Patients with PR3-ANCA-positive EGPA are rare and their phenotype more closely resembles GPA than typical EGPA. 1
Clinical Pitfall to Avoid
Do not confuse the ANCA patterns between GPA and EGPA. GPA is strongly associated with c-ANCA/PR3-ANCA (80-90% positive), while EGPA shows p-ANCA/MPO-ANCA in only 30-40% of cases. 1, 5 The presence of c-ANCA should redirect your diagnostic thinking toward GPA rather than EGPA. 1