Masson bodies
Summary
Masson bodies are plugs of loose fibromyxoid granulation tissue that fill alveolar ducts and alveoli in organizing pneumonia. They are the histological hallmark of cryptogenic organizing pneumonia, previously called bronchiolitis obliterans organizing pneumonia (BOOP).
Detail
Masson bodies represent an intraluminal fibroproliferative response to alveolar injury: fibroblasts and myofibroblasts in a myxoid matrix form polypoid plugs within distal airspaces while the underlying alveolar architecture stays intact. That preserved architecture is why organizing pneumonia is potentially fully reversible and typically responds briskly to corticosteroids, unlike usual interstitial pneumonia, where destruction and honeycombing are permanent. Organizing pneumonia may be cryptogenic or secondary to infection, drugs (amiodarone, bleomycin), connective tissue disease, radiation, or transplant. Patients present subacutely with cough, dyspnoea, and flu-like illness, and imaging shows patchy peripheral or peribronchial consolidation that characteristically migrates and fails to respond to antibiotics.
Sources
- Robbins Basic Pathology
- Harrison's Principles of Internal Medicine
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