Organising pneumonia is an inflammatory and fibroproliferative lung reaction leading to a clinico-radiologic-pathological syndrome. It may occur with no detectable cause (cryptogenic) or may be associated with various processes including, among others, infections, drugs, and connective disorders. The clinical picture is usually subacute and may include fever, fatigue, weight loss, cough, dyspnoea, crackles, and can progress to respiratory failure. At imaging, the most typical pattern consists of multiple subpleural consolidations. Open lung biopsy can be necessary to confirm the diagnosis, showing buds of loose connective tissue filling the lung alveoli. In our case, bronchoscopic transbronchial biopsy with a cryoprobe3
was sufficient to confirm the diagnosis. Most patients respond well to moderate doses of prednisone from 1–3 months. Data coming especially from autopsy studies after influenza pandemics describe a large spectrum of lung changes associated with viral pneumonia. Later stages of influenza virus pneumonia can be associated with organising pneumonia with diffuse alveolar damage and fibrosis.4
In a recent article, seven patients with confirmed H1N1 infection were followed according to the radiographic and chest CT findings. The most common alterations were ground glass opacities, with or without areas of consolidation, with predominant peribronchovascular and subpleural distribution, resembling organising pneumonia.5
There have been radiologically suspected cases of organising pneumonia, but no biopsy proven cases, and to our knowledge no histological confirmation of organising pneumonia secondary to H1N1 infection has been reported. Oseltamivir is indicated in patients admitted to hospital with confirmation of influenza A or in patients included in risk groups. In our case, oseltamivir could not prevent the subacute development of organising pneumonia.
Although this is a single observation, we highlight that:
- Organising pneumonia should also be considered as a possible complication of influenza A (H1N1) infection.
- Patients diagnosed with organising pneumonia secondary to H1N1 can benefit from early diagnosis and appropriate specific management.