A 48-year-old non-smoker has progressive exertional breathlessness. HRCT shows bilateral peripheral subpleural consolidation with perilobular opacities, no honeycombing, and areas that migrate on serial imaging. Surgical biopsy shows polypoid plugs of loose fibroblastic connective tissue filling distal bronchioles and alveolar ducts. The diagnosis is:
- A Idiopathic pulmonary fibrosis with usual interstitial pneumonia pattern
- B Cryptogenic organizing pneumonia ✓
- C Pulmonary Langerhans cell histiocytosis
- D Lymphangitic carcinomatosis
Explanation
Polypoid plugs of pale, loosely arranged myofibroblastic tissue, historically called Masson bodies, bridging bronchioles and alveoli define organizing pneumonia. Clinically it presents with a restrictive picture, migratory peripheral consolidation on imaging, absence of honeycombing, and striking response to corticosteroids, unlike UIP which shows temporal heterogeneity, honeycombing, fibroblastic foci, and progressive irreversibility. Langerhans cell histiocytosis gives nodules and bizarre cysts in smokers, while lymphangitic carcinomatosis shows tumor in perilymphatic channels.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.