20th February 2025

Cryptogenic organising pneumonia (COP)

This is a type of ILD where alveoli become congested with granulation tissue. Organising pneumonias can be cryptogenic (of uncertain origin) or secondary to other insults (infection, drugs, malignancy, etc).

Symptoms of breathlessness and cough typically develop in less than three months and patients may complain of an unresolved chest infection. Clubbing is not present on examination.

Diagnosis is usually made based on clinical features, HRCT and biopsy results.

• HRCT usually shows patchy consolidation with or without ground glass, in a predominantly subpleural and/or peribronchial distribution. Nodules or masses ranging in size might be seen, which can occasionally lead to an erroneous suspicious of malignancy 
• Histology reveals patchy ‘plugging’ of alveolar spaces, and sometimes bronchioles, with granulation tissue

Prognosis is generally good and most patients respond well to steroids, which are the mainstay of treatment. Steroid courses of 6-12 months are usually indicated. If steroid therapy fails, other immunosuppressants such as azathioprine or cyclophosphamide might be used.