Organizing pneumonia

Last revised by Dr Daniel J Bell on 18 Feb 2021

Organizing pneumonia (OP) refers to a clinicopathological entity which is associated with non-specific clinical findings, radiographic findings, and pulmonary function test (PFT) 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 5,6.

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. ​

Most (especially cryptogenic forms) respond very well to corticosteroid treatment; however, a small percentage of patients may develop progressive fibrosis -  fibrosing organizing pneumonia 7.

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Cases and figures

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