A 52-year-old pigeon keeper has 6 months of progressive dyspnea with weight loss. Examination reveals bilateral inspiratory squeaks. HRCT shows diffuse centrilobular ground-glass nodules with mosaic attenuation and lobular air trapping on expiratory images. Bronchoalveolar lavage fluid shows 45% lymphocytes. Which diagnosis explains these findings?
- A Nonspecific interstitial pneumonia
- B Pulmonary alveolar proteinosis
- C Hypersensitivity pneumonitis ✓
- D Desquamative interstitial pneumonia
Correct answer: C. Hypersensitivity pneumonitis
Explanation
Chronic avian antigen exposure plus a BAL lymphocytosis above 30%, centrilobular ground-glass nodules, mosaic attenuation and lobular air trapping define hypersensitivity pneumonitis, a cell-mediated granulomatous reaction to inhaled organic antigen. NSIP is subpleural and basal with uniform reticulation rather than centrilobular nodules, DIP occurs in smokers with pigmented intra-alveolar macrophages, and alveolar proteinosis shows crazy paving with milky PAS-positive lavage fluid rather than lymphocytosis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.