A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 45-year-old woman presents to the emergency department due to new-onset symptoms of asthma. She reports that the asthmatic attacks started a week ago. The past medical history includes gastroesophageal reflux disease and hepatitis B. On physical examination, the patient has bilateral foot drop as well as numbness and tingling sensation in all extremities. A complete blood count is relevant for eosinophilia of 9.1 × 108/L. Which of the markers below could explain all of the patient’s current symptoms?
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A
ESRIncorrect. ESR is a nonspecific inflammatory marker that would be elevated in many conditions—it doesn't specifically explain the asthma + neuropathy + eosinophilia triad.
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B
p-ANCACorrect. p-ANCA (anti-MPO) is positive in eosinophilic granulomatosis with polyangiitis (Churg-Strauss), which causes new-onset asthma, eosinophilia, and mononeuritis multiplex (bilateral foot drop).
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C
HLA B-27Incorrect. HLA-B27 is associated with seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis)—not vasculitis with asthma and eosinophilia.
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D
Anti-histone antibodiesIncorrect. Anti-histone antibodies indicate drug-induced lupus, which presents with arthralgia, serositis, and rash—not the asthma/eosinophilia/neuropathy picture of EGPA.
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E
c-ANCAIncorrect. c-ANCA (anti-PR3) is associated with granulomatosis with polyangiitis (Wegener), which causes upper/lower respiratory tract granulomas and glomerulonephritis—not the asthma + eosinophilia + mononeuritis multiplex triad of EGPA, which is p-ANCA positive.
↑ Tap an answer to reveal the reasoning
Answer: B. A 45-year-old with new-onset asthma, peripheral neuropathy (mononeuritis multiplex—bilateral foot drop + paresthesias), and marked eosinophilia (>1.5 × 10^9/L) is the textbook presentation of eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Churg-Strauss syndrome. EGPA is an ANCA-associated small- and medium-vessel vasculitis characterized by: (1) asthma, (2) eosinophilia (often >10% of WBCs or >1500/μL), (3) sinusitis/nasal polyposis, (4) eosinophilic infiltration of organs (pulmonary infiltrates, eosinophilic gastroenteritis, cardiac involvement), (5) vasculitis (mononeuritis multiplex from vasculitis of vasa nervorum), and (6) extravascular eosinophilic granulomas.
Approximately 40–60% of EGPA patients are positive for ANCA, predominantly p-ANCA (perinuclear staining pattern, anti-myeloperoxidase/MPO). The other ANCA-associated vasculitides are granulomatosis with polyangiitis (GPA, formerly Wegener's; c-ANCA/anti-PR3) and microscopic polyangiitis (MPA; p-ANCA/anti-MPO).
Mononeuritis multiplex is the classic neurologic manifestation, caused by vasculitis of the vasa nervorum supplying individual peripheral nerves—producing patchy, asymmetric deficits (e.g., bilateral foot drop from peroneal nerve involvement). Treatment is high-dose corticosteroids; cyclophosphamide or rituximab is added for severe organ-threatening disease.
Distinguishers: ESR is nonspecific (elevated in any inflammation) and doesn't explain the syndrome. HLA-B27 is associated with seronegative spondyloarthropathies. Anti-histone antibodies indicate drug-induced lupus, not vasculitis.
**Why each option:**
**A.** ESR is a nonspecific inflammatory marker that would be elevated in many conditions—it doesn't specifically explain the asthma + neuropathy + eosinophilia triad.
**B.** Correct. p-ANCA (anti-MPO) is positive in eosinophilic granulomatosis with polyangiitis (Churg-Strauss), which causes new-onset asthma, eosinophilia, and mononeuritis multiplex (bilateral foot drop).
**C.** HLA-B27 is associated with seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis)—not vasculitis with asthma and eosinophilia.
**D.** Anti-histone antibodies indicate drug-induced lupus, which presents with arthralgia, serositis, and rash—not the asthma/eosinophilia/neuropathy picture of EGPA.