Organizing pneumonia (OP) refers to a clinicopathological entity which is associated with non-specific clinical findings, radiographic findings, and pulmonary function test results.
When an underlying cause is unknown it is classified as cryptogenic organizing pneumonia (COP; also referred to as primary organizing pneumonia) whereas if a cause is known it is then termed a secondary organizing pneumonia.
Most cases of organizing pneumonia (50-70%) are classified as cryptogenic .
Organizing pneumonia comprises a histological pattern characterized by granulation tissue polyps within alveolar ducts and alveoli and with chronic inflammation involving the adjacent lung parenchyma.
Treatment and prognosis
Most (especially cryptogenic forms) respond very well to corticosteroid treatment; however, a small percentage of patients many develop progressive fibrosis - fibrosing organizing pneumonia .