Cryptogenic organizing pneumonia | |
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Micrograph showing a Masson body (off center left/bottom of the image – pale circular and paucicellular), as may be seen in cryptogenic organizing pneumonia. The Masson body plugs the airway. The artery associated with the obliterated airway is also seen (far left of the image). H&E stain. | |
Specialty | Pulmonology |
Classification | |
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External resources |
Cryptogenic organizing pneumonia (COP) also known as bronchiolitis obliterans organizing pneumonia (BOOP, not to be confused with bronchiolitis obliterans) is a form of non-infectious pneumonia; more specifically, COP is an inflammation of the bronchioles (bronchiolitis) and surrounding tissue in the lungs. It is often a complication of an existing chronic inflammatory disease such as rheumatoid arthritis, dermatomyositis, or it can be a side effect of certain medications such as amiodarone. COP was first described by Gary Epler in 1985.
The clinical features and radiological imaging resemble infectious pneumonia. However, diagnosis is suspected after there is no response to multiple antibiotics, and blood and sputum cultures are negative for organisms.
"Organizing" refers to unresolved pneumonia (in which the alveolar exudate persists and eventually undergoes fibrosis) in which fibrous tissue forms in the alveoli. The phase of resolution and/or remodeling following bacterial infections is commonly referred to as organizing pneumonia, both clinically and pathologically.
The American Thoracic Society and the European Respiratory Society hold that "cryptogenic organizing pneumonia" is the preferred clinical term for this disease for multiple reasons:
The classic presentation of COP is the development of nonspecific systemic (e.g., fevers, chills, night sweats, fatigue, weight loss) and respiratory (e.g. difficulty breathing, cough) symptoms in association with filling of the lung alveoli that is visible on chest x-ray. This presentation is usually so suggestive of an infection that the majority of patients with COP have been treated with at least one failed course of antibiotics by the time the true diagnosis is made.