Cryptogenic organising pneumonia (COP) is a disease of unknown aetiology. A variety of infectious as well as non infectious causes have been associated.
Organizing pneumonia (OP) is a histologic pattern of alveolar inflammation with varied aetiology (including pulmonary infection). The idiopathic form of OP is called cryptogenic organizing pneumonia (COP) and it belongs to idiopathic interstitial pneumonias (IIP's).
COP was previously termed bronchiolitis obliterans organizing pneumonia (BOOP) : (not to be confused with bronchiolitis obliterans per se).8
Epidemiology and clinical presentation
Presentation is commonest in the 55 - 60 age group. Patients present with short history (i.e less than ~ 2 months) of breathlessness, non productive cough, weight loss, malaise and fever. There is no association with smoking.
In addtion to the alveolar inflammatory changes found with a normal pneumonia, there is also involvement of the bronchioles.
Histologically, it is characterized by the presence of buds of granulation tissue (Masson bodies) in the distal airspaces which may cause secondary bronchiolar occlusion due to extension of the inflammatory process. Hence, the reason for being perviously termed bronchiolitis obliterans organizing pneumonia (BOOP).
- bilateral patchy areas ( commonest finding 3 ) : often migratory
- can affect all lung zones
- usually peripheral, sub-pleural, peribronchovascular 2
- foci of granulation tissue up to 1 cm
- may simulate neoplasm if > 5 cm in size
- may be numerous in immunocompromised patients
The most common HRCT features include 6:
- patchy consolidation with a predominantly subpleural and / or peribronchial distribution
- small, ill-defined peribronchial or peribronchiolar nodules
- large nodules or masses
- bronchial wall thickening or dilatation in the abnormal lung regions
- a perilobular pattern with ill-defined linear opacities that are thicker than the thickened interlobular septa and have an arcade or polygonal appearance
- ground glass opacity or crazy paving
It was first described by Davison and colleagues in 1983.
Treatment and prognosis
Corticosteroids have been widely used and most patients recover completely 3-4.
On plain film consider
- differential for peripheral consolidation : reverse bat wing opactities
- differential for bilateral airspace opacities
On HRCT consider
- 1. McQueen AS, Grant LA, Grant L et-al. Grainger & Allison's Diagnostic Radiology, Single Best Answer Mcqs. Churchill Livingstone. (2009) ISBN:0702031496. Read it at Google Books - Find it at Amazon
- 2. Lee KS, Kullnig P, Hartman TE et-al. Cryptogenic organizing pneumonia: CT findings in 43 patients. AJR Am J Roentgenol. 1994;162 (3): 543-6. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. Montesinos JJ, Laguna MA. Case 1: Cryptogenic organizing pneumonia. AJR Am J Roentgenol. 1998;171 (3): 835, 838-9. AJR Am J Roentgenol (citation) - Pubmed citation
- 4. Wittram C, Mark EJ, McLoud TC. CT-histologic correlation of the ATS/ERS 2002 classification of idiopathic interstitial pneumonias. Radiographics. 23 (5): 1057-71. doi:10.1148/rg.235035702 - Pubmed citation
- 5. Kim SJ, Lee KS, Ryu YH et-al. Reversed halo sign on high-resolution CT of cryptogenic organizing pneumonia: diagnostic implications. AJR Am J Roentgenol. 2003;180 (5): 1251-4. AJR Am J Roentgenol (full text) - Pubmed citation
- 6. Webb WR, Műller NL, Naidich DP. High-resolution CT of the lung. Lippincott Williams & Wilkins. (2008) ISBN:0781769094. Read it at Google Books - Find it at Amazon
- 7. Cordier JF. Cryptogenic organising pneumonia. Eur. Respir. J. 2006;28 (2): 422-46. doi:10.1183/09031936.06.00013505 - Pubmed citation
- 8. Demedts M, Costabel U. ATS/ERS international multidisciplinary consensus classification of the idiopathic interstitial pneumonias. Eur. Respir. J. 2002;19 (5): 794-6. Eur. Respir. J. (link) - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Bronchiolitis obliterans organizing pneumonia (BOOP)||✗|
|Cryptogenic Organizing Pneumonia (COP)||✗|
|Bronchiolitis obliterans organising pneumonia (BOOP)||✗|
|Cryptogenic organising pneumonia (COP)||✗|
|Cryptogenic organizing pneumonia||✗|