ABSTRACT
The terms cryptogenic organizing pneumonia (COP) and idiopathic bronchiolitis obliterans with organizing pneumonia (BOOP) are synonymous. Typical COP should be viewed as a clinicopathological syndrome,
consisting of respiratory and systemic symptoms (usually low-grade), patchy consolidation
on chest radiography and computed tomography, a restrictive defect on pulmonary function
testing, and the presence of buds of granulation tissue within the distal airways
and alveolar spaces. In the correct clinical context, the diagnosis can be secured
by transbronchial biopsy, with typical bronchoalveolar lavage features providing useful
diagnostic support. In typical COP, corticosteroid therapy is highly effective; an
early trial of withdrawal of treatment is appropriate because relapse of COP is not
associated with a poor long-term outcome. Atypical forms of COP are outlined in this
article, including focal, explosive, progressive fibrotic, and nonprogressive fibrotic
variants. The occasional evolution of COP into a progressive fibrotic disorder is
associated with a poor long-term outcome and poses particular therapeutic difficulties.
KEYWORD
Cryptogenic organizing pneumonia - bronchiolitis obliterans organizing pneumonia -
prognosis