Organizing Pneumonia Phenotype

Organizing pneumonia (OP) is a nonspecific lung parenchymal response to any form of injury, with its idiopathic variant coined as cryptogenic organizing pneumonia (COP). The hallmark pathological features are presence of polypoid granulation tissue, or Masson bodies, in the alveolar spaces, with lung architecture preserved in most patients with good clinical outcomes poststeroid treatment. Clinically, patients exhibit signs and symptoms of subclinical or subacute infection that do not respond to antibiotics. Computed Tomography (CT) plays a vital role in establishing the diagnosis, monitoring of OP, and for better understanding of its imaging phenotypes which are crucial for clinical decision making. This article highlights the 3 main imaging patterns of OP on CT, the classic, nodular and fibrotic forms. Identifying these diverse imaging features holds the key for precise diagnosis of OP.