Cryptogenic organizing pneumonia
- COP is an idiopathic intersitial pneumonias with characteristic clinical and radiologic features.
- The histologic pattern of COP is organizing pneumonia, formerly referred to as bronchiolitis obliterans organizing pneumonia (BOOP).
- The term BOOP has been omitted to avoid confusion with airway diseases such as constrictive bronchiolitis.
- Mean age of 55 years.
- Present with mild dyspnea, cough, and fever that have been developing over a few weeks.
- Patients typically report a respiratory tract infection preceding their symptoms.
- There is no association with cigarette smoking
- The majority of patients recover completely after administration of corticosteroids, but relapses occur frequently within 3 months after corticosteroid therapy.
 Imaging Findings
 Plain film
- The chest radiograph in patients with COP usually shows unilateral or bilateral patchy consolidations that resemble pneumonic infiltrates.
- However, the consolidations in COP do not represent an active pneumonia but result from intraalveolar fibroblast proliferations.
- Some patients present with nodular opacities on the chest radiograph.
- Frequently, the CT findings are far more extensive than expected from a review of the plain chest radiograph.
- Characteristic peripheral or peribronchial distribution, and the lower lung lobes are more frequently involved.
- In some cases, the outermost subpleural area is spared.
- Typically, the appearance of the lung opacities varies from ground glass to consolidation.
- These opacities have a tendency to migrate, changing location and size, even without treatment.
- They are of variable size, ranging from a few centimeters to an entire lobe.
- Reversed halo sign
 See Also
- Usual interstitial pneumonia (UIP)
- Nonspecific interstitial pneumonia (NSIP)
- Respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- Desquamative interstitial pneumonia (DIP)
- Lymphoid interstitial pneumonia (LIP)
- Acute interstitial pneumonia (AIP)
 External Links
- Christina Mueller-Mang, Claudia Grosse, Katharina Schmid, Leopold Stiebellehner, and Alexander A. Bankier. What Every Radiologist Should Know about Idiopathic Interstitial Pneumonias. RadioGraphics 2007 27: 595-615.