Restrictive Lung Disease USMLE Step 1 Practice Question
A 35-year-old grain silo worker presents 4 hours after occupational exposure with acute fever (38.9°C), productive cough, and dyspnea. Vital signs show HR 102/min, RR 24/min, BP 128/82 mmHg, SpO2 92% on room air. Chest X-ray demonstrates bilateral diffuse alveolar infiltrates. Pulmonary function testing reveals reduced FVC and DLCO with normal bronchodilator response. He denies orthopnea. Which of the following best explains the underlying pathophysiologic mechanism?
Answer choices
- ADirect toxic injury from chemical fumes
- BType I hypersensitivity with anaphylaxis
- CBacterial infection from contaminated grain
- DType III and IV hypersensitivity reaction to organic antigenCorrect answer
- EChronic cumulative asbestos exposure
- FAcute fungal infection with Aspergillus fumigatus colonization
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