Bronchiolitis obliterans
Bronchiolitis obliterans (BO), also known as obliterative bronchiolitis, constrictive bronchiolitis and popcorn lung, is a disease that results in obstruction of the smallest airways of the lungs (bronchioles) due to inflammation. Symptoms include a dry cough, shortness of breath, wheezing and feeling tired. These symptoms generally get worse over weeks to months. It is not related to cryptogenic organizing pneumonia, previously known as bronchiolitis obliterans organizing pneumonia.
| Bronchiolitis obliterans | |
|---|---|
| Other names | Constrictive bronchiolitis, Obliterative bronchiolitis, Popcorn lung |
| High resolution CT scan showing bronchiolitis obliterans with mosaic attenuation, bronchiectasis, air trapping and bronchial thickening | |
| Specialty | Pulmonology |
| Symptoms | Dry cough, shortness of breath, wheezing, feeling tired |
| Usual onset | Worsens over weeks to months in rare cases. |
| Causes | Toxic fumes, respiratory infections, connective tissue disorder, following a bone marrow or heart-lung transplant |
| Diagnostic method | CT scan, pulmonary function tests, lung biopsy |
| Differential diagnosis | Asthma |
| Treatment | Corticosteroids, immunosuppressive medication, lung transplant |
| Prognosis | Often poor |
| Frequency | Rare |
Causes include breathing in toxic fumes, respiratory infections, connective tissue disorder or complications following a bone marrow or heart-lung transplant. Symptoms may not occur until two to eight weeks following toxic exposure or infection. The underlying mechanism involves inflammation that results in scar tissue formation. Diagnosis is by CT scan, pulmonary function tests or lung biopsy. A chest X-ray is often normal.
While the disease is not reversible, treatments can slow further worsening. This may include the use of corticosteroids or immunosuppressive medication. A lung transplant may be offered. Outcomes are often poor, with most people dying in months to years.
Bronchiolitis obliterans is rare in the general population. It, however, affects about 75% of people by ten years following a lung transplant and up to 10% of people who have received a bone marrow transplant from someone else. The condition was first clearly described in 1981. Prior descriptions occurred as early as 1956, with the term "bronchiolitis obliterans" used first by Reynaud in 1835.