A 55-year-old man presents with dry cough and progressive dyspnea for 2 months. CT shows bilateral ground-glass opacities with consolidation in a peripheral, subpleural distribution. Transbronchial biopsy shows organizing fibrosis with intraluminal polyps of loose connective tissue within bronchioles and alveolar ducts. What is the diagnosis?

• A Diffuse alveolar damage (DAD)
• B Respiratory bronchiolitis-associated ILD
• C Non-specific interstitial pneumonia (NSIP)
• D Organizing pneumonia (cryptogenic organizing pneumonia/BOOP) ✓

Explanation

Organizing pneumonia (BOOP/COP) is characterized by intraluminal polyps of loose connective tissue (Masson bodies) within bronchioles and alveolar ducts, with peripheral subpleural ground-glass opacities and consolidation on CT. DAD shows hyaline membranes. NSIP shows diffuse interstitial inflammation or fibrosis without intraluminal polyps. RB-ILD shows pigmented macrophages in centrilobular regions.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.