A 48-year-old pigeon breeder presents with 6 months of progressive dyspnoea and dry cough, worse at work and improving on holidays. Examination reveals fine inspiratory crackles. HRCT shows diffuse centrilobular ground-glass nodules, patchy mosaic attenuation with air trapping on expiratory images, and sparing of the lung bases. Which pattern does this represent?
- A Pulmonary alveolar proteinosis
- B Usual interstitial pneumonia
- C Non-fibrotic hypersensitivity pneumonitis ✓
- D Desquamative interstitial pneumonia
Correct answer: C. Non-fibrotic hypersensitivity pneumonitis
Explanation
Centrilobular ground-glass nodules with three-density mosaic attenuation and air trapping reflect peribronchiolar inflammation and small airway involvement, the hallmark of non-fibrotic hypersensitivity pneumonitis; the exposure history and improvement away from the antigen support it. UIP shows basal subpleural honeycombing without air trapping. Alveolar proteinosis shows crazy paving with geographic sparing. Desquamative interstitial pneumonia occurs in smokers with lower zone ground glass and lacks centrilobular nodularity and air trapping.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.