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Organizing Pneumonia (Cryptogenic Organizing Pneumonia / BOOP)

Inflammatory pulmonary disease characterized by intra-alveolar fibroblastic plugs and patchy infiltrates, often subacute, that responds dramatically to corticosteroids.

Written by: Saygı Hospital Health Guide Editorial Board
Published:

This content is for general information; please consult your physician for diagnosis and treatment.

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What is Organizing Pneumonia (Cryptogenic Organizing Pneumonia / BOOP)?

Organizing pneumonia is a histopathologic pattern of lung injury characterized by intraluminal granulation tissue plugs (Masson bodies) within alveolar ducts and adjacent alveoli, with preserved lung architecture. Etiology can be cryptogenic (idiopathic, COP — about 50% of cases) or secondary to identifiable triggers.

Secondary causes: post-infectious (viral, bacterial, mycoplasma, fungal — including COVID-19), drug-induced (amiodarone, nitrofurantoin, statins, methotrexate, immune checkpoint inhibitors), connective tissue diseases (RA, dermatomyositis, Sjögren), radiation pneumonitis, post-transplant, hematologic malignancy, aspiration, or environmental exposure.

Imaging shows patchy peripheral or peribronchovascular consolidation with air bronchograms, often migratory, sometimes with reverse halo sign (atoll sign — peripheral consolidation surrounding ground-glass center). HRCT findings combined with clinical context strongly suggest the diagnosis; lung biopsy (transbronchial or VATS) confirms when needed.

Symptoms

Subacute onset over weeks to months
Persistent dry or productive cough
Dyspnea on exertion, gradually progressive
Constitutional symptoms: fever, malaise, weight loss, night sweats
Chest discomfort, sometimes pleuritic
Crackles on auscultation
Failure of empirical antibiotic therapy for community-acquired pneumonia
Migratory pulmonary infiltrates on serial imaging

Risk Factors

Age 50–70 years (peak incidence)
Recent respiratory infection (viral, COVID-19)
Connective tissue disease (RA, dermatomyositis, Sjögren)
Drug exposure (amiodarone, nitrofurantoin, immune checkpoint inhibitors, methotrexate)
Radiation therapy to chest
Hematopoietic stem cell or solid organ transplantation
Inflammatory bowel disease (rare association)
Hematologic malignancy and chemotherapy

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Persistent cough and dyspnea unresponsive to antibiotics — pulmonologist referral
  • New-onset pulmonary infiltrates with fever — workup for OP and infection
  • Migratory or recurrent pulmonary opacities on imaging
  • Worsening symptoms during taper of corticosteroids — relapse evaluation
  • Pulmonary symptoms in patient with connective tissue disease — consider secondary OP

Treatment Methods

01
Diagnostic workup: HRCT chest, BAL (lymphocytosis with low CD4/CD8 ratio supports diagnosis), exclude infection (cultures, PCR for respiratory viruses, atypical pathogens), connective tissue serology (ANA, RF, anti-CCP, myositis panel), drug history review
02
Lung biopsy: transbronchial cryobiopsy or VATS biopsy when imaging and clinical features are atypical or response to therapy uncertain
03
First-line: oral prednisolone 0.5–1 mg/kg/day for 4–8 weeks then gradual taper over 6–12 months total; rapid clinical and radiologic response within days to weeks
04
Relapse common (30–50% during taper): re-escalate corticosteroids, consider corticosteroid-sparing agents (azathioprine, mycophenolate mofetil, cyclosporine) for recurrent disease or steroid-intolerant patients
05
Macrolide therapy (clarithromycin, azithromycin) for milder cases or steroid-sparing in selected patients
06
Identify and remove offending agent: discontinue causative drug, address connective tissue disease activity
07
Acute fibrinous and organizing pneumonia (AFOP) variant: more severe, may require ICU support and pulse methylprednisolone
08
Long-term follow-up: serial spirometry, HRCT at 3 and 6 months, monitor for relapse during taper, screen for underlying connective tissue disease
09
Pulmonary rehabilitation, smoking cessation, vaccination (influenza, pneumococcal, COVID-19)
10
Multidisciplinary discussion (pulmonology, rheumatology, radiology, pathology) for atypical presentations

Which Department to Visit?

You can visit our Göğüs Hastalıkları department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.