Cryptogenic organizing pneumonia

Discussion

COP is an idiopathic interstitial pneumonia 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.

Clinical Features

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.

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.

Patient #1

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.