Cryptogenic organizing pneumonia (COP), previously known as Bronchilitis Obliterans Organizing Pneumonia (BOOP), is a distinct clinical entity with predominant features of pneumonia.
To summarize:
- It usually occurs in fifth or sixth decades of life.
- Men and women are affected equally.
- Most patients are symptomatic for less than two months, with a clinical presentation that mimics community-acquired pneumonia.
- Multiple ground-glass opacities and/or consolidations (with air bronchograms) are commonly noted on imaging.
- An open or thoracoscopic lung biopsy is suggested to confirm the diagnosis.
- Histopathology typically demonstrates excessive proliferation of granulation tissue within small airways (proliferative bronchiolitis) and alveolar ducts, associated with chronic inflammation in the surrounding alveoli.
- The diagnosis of COP requires positive histopathology AND the exclusion of any other possible cause of pneumonia (in particular, infectious causes).
- Glucocorticoid therapy typically induces rapid clinical improvement and clearing of the opacities on chest imaging, usually without significant sequelae.
- Relapses are common upon tapering or discontinuation of glucocorticoids.
- It can be idiopathic, but also associated with connective tissue diseases, a variety of drugs, malignancy, and other interstitial pneumonias.
Please click on this link to read an excellent 2011 review from Chest on this topic.
