A 60-year-old woman presents with progressive dyspnea and dry cough. HRCT shows bilateral, symmetric, ground-glass opacities with a mosaic attenuation pattern. Pulmonary function tests reveal an obstructive pattern with air trapping. Which diagnosis best explains these findings?
- A Idiopathic pulmonary fibrosis
- B Usual interstitial pneumonia
- C Hypersensitivity pneumonitis ✓
- D Sarcoidosis
Correct answer: C. Hypersensitivity pneumonitis
Explanation
Hypersensitivity pneumonitis characteristically shows bilateral ground-glass opacities with mosaic attenuation on expiratory CT, reflecting air trapping in small airway disease. Both IPF and UIP show basal-predominant honeycombing and a restrictive pattern, not obstructive. Sarcoidosis shows perilymphatic nodules and upper lobe predominance, not mosaic attenuation with obstruction.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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