Cryptogenic Organizing Pneumonia
Basics
Description
- Cryptogenic organizing pneumonia or COP is the idiopathic inflammatory process of diffuse interstitial granulation extending to the distal airways and alveoli.
- As opposed to secondary organizing pneumonia that has multiple causative etiologies such as medication, infection, connective tissue disease, malignancy, and so forth, COP has no known precipitant.
- May have a gradual or sudden onset
- Unknown pathogenesis
- Chest x-ray (CXR) typically shows a pattern of bilateral, diffuse, or patchy infiltrates and consolidative or ground-glass opacifications. There may be air bronchograms as well.
- Completely reversible restrictive problem. Most cases will respond to corticosteroids, which may have to be given for a year or more.
- Synonym(s): previously known as bronchiolitis obliterans with organizing pneumonia or BOOP; intraluminal fibrosis of distal airways; idiopathic BOOP; obliterative bronchiolitis
Geriatric Considerations
More common than originally thought and may be sudden and very severe in geriatric patients
Pediatric Considerations
Rare but has been reported after viral pneumonia
Epidemiology
- Incidence/prevalence in the United States: estimated at 0.01% but may be underdiagnosed
- Predominant age: most commonly seen in age 50s to 60s
- Males and females affected equally
Prevalence
Unknown
Etiology and Pathophysiology
Idiopathic: a specific complex reaction of lung tissue leading to alveolar wall injury
Genetics
No known genetic component
Risk Factors
- Immunocompromised patients, including transplant recipients and AIDS patients
- Other autoimmune conditions
- Gastroesophageal reflux disease causing microaspiration
- Reported frequency of tobacco use in diagnosed cases 25–50%, making smoking unlikely to be a precipitating factor
General Prevention
Except for prevention of relapse, none known
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Citation
Domino, Frank J., et al., editors. "Cryptogenic Organizing Pneumonia." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688229/all/Cryptogenic_Organizing_Pneumonia.
Cryptogenic Organizing Pneumonia. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688229/all/Cryptogenic_Organizing_Pneumonia. Accessed December 3, 2024.
Cryptogenic Organizing Pneumonia. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688229/all/Cryptogenic_Organizing_Pneumonia
Cryptogenic Organizing Pneumonia [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 03]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688229/all/Cryptogenic_Organizing_Pneumonia.
* Article titles in AMA citation format should be in sentence-case
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T1 - Cryptogenic Organizing Pneumonia
ID - 1688229
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ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688229/all/Cryptogenic_Organizing_Pneumonia
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