What is bronchiolitis obliterans?
Bronchiolitis obliterans, also called obliterative or constrictive bronchiolitis, is a rare condition in which the smallest airways of the lung (the bronchioles) become inflamed and then scarred. The scar tissue narrows or completely blocks these tiny tubes, so air becomes trapped and breathing out is difficult.
The resulting airflow obstruction does not reverse with inhalers in the way that asthma does, and it is often mistaken for asthma or COPD. The diagnosis matters because the causes, monitoring and treatment are different.
Bronchiolitis obliterans should not be confused with organising pneumonia, a different and usually steroid-responsive condition that was once known by a similar name. Depending on the cause, care is shared with transplant, haematology, rheumatology or paediatric teams. Children are managed jointly with paediatric pulmonology.
Symptoms of bronchiolitis obliterans
Symptoms usually develop over weeks to months and may be subtle at first:
- Breathlessness on exertion: gradually increasing and often the main complaint.
- Persistent dry cough: not explained by infection.
- Wheeze that responds poorly to reliever inhalers.
- Recurrent chest infections, particularly in later stages.
- Fatigue and reduced exercise tolerance.
In transplant recipients, a fall in lung function on routine testing may be detected before any symptoms appear.
Causes and risk factors
Bronchiolitis obliterans is a response to injury of the small airways. Recognised causes include:
- Lung transplantation: as chronic lung allograft dysfunction, the main long-term limitation of lung transplant.
- Bone marrow (haematopoietic stem cell) transplantation: as a form of chronic graft-versus-host disease.
- Severe childhood infections: especially adenovirus, measles and mycoplasma, sometimes producing a one-sided form known as Swyer-James-MacLeod syndrome.
- Inhaled toxic exposures such as nitrogen dioxide, sulphur mustard, ammonia, flavouring chemicals (diacetyl) and fire smoke.
- Autoimmune disease: most often rheumatoid arthritis.
- Certain drugs and dietary agents, and rarely DIPNECH.
In some patients no cause is found.
How bronchiolitis obliterans is diagnosed
A chest X-ray is frequently normal, so diagnosis relies on breathing tests and CT scanning together with the clinical history.
| Test | What it shows |
|---|---|
| Spirometry | Fixed airflow obstruction with little or no improvement after a bronchodilator |
| Full lung function tests | Air trapping, shown by a raised residual volume |
| High-resolution CT with inspiratory and expiratory images | Mosaic attenuation and air trapping on breathing out |
| Bronchoscopy | Excludes infection or rejection in transplant recipients |
| Lung biopsy | Rarely needed, because small airway disease is patchy and easily missed |
After lung or bone marrow transplant, diagnosis is often based on a sustained fall in FEV1 compared with the highest value achieved after transplant, once other causes have been excluded. Regular spirometry is therefore important in these groups.
Treatment of bronchiolitis obliterans
Established scarring cannot be reversed, so treatment aims to stop progression, treat the underlying cause and support breathing.
Treating the cause
This means removing any toxic exposure, adjusting immunosuppression after transplant in partnership with the transplant team, or controlling the underlying autoimmune disease.
Medicines
Long-term azithromycin is used, particularly after lung transplant, for its anti-inflammatory effect. After bone marrow transplant, the combination of an inhaled corticosteroid with a long-acting bronchodilator, azithromycin and montelukast is commonly used. Systemic treatments for graft-versus-host disease, such as ruxolitinib, are directed by the haematology team.
Supportive care
Pulmonary rehabilitation, prompt treatment of infections, vaccination, airway clearance where mucus is a problem, and oxygen where levels are low all help. For severe, progressive disease, referral to a transplant centre or re-transplantation may be discussed.
Outlook and living with the condition
The course varies widely. Disease following childhood infection or a single toxic exposure often stabilises, while transplant-related disease may progress and needs close monitoring. Regular spirometry, often including home monitoring after transplant, helps detect decline early so that treatment can be adjusted. Staying active, avoiding smoke and pollution and keeping vaccinations up to date support long-term lung health.
When to seek urgent care
Seek medical help promptly for breathlessness at rest, a sudden drop in home spirometry readings, fever with cough in a transplant recipient, coughing up blood, chest pain or blue lips. Infections can progress quickly in people on immunosuppressive treatment.
Frequently asked questions
Is bronchiolitis obliterans the same as bronchiolitis in babies?
No. Bronchiolitis in babies is a common, usually short-lived viral infection. Bronchiolitis obliterans is a rare, long-term scarring of the small airways, although a severe infection in early childhood can occasionally lead to it.
Can bronchiolitis obliterans be reversed?
The scarring itself cannot be reversed. Treatment aims to stop further damage, and many patients stabilise, especially when the cause has been removed.
Why do my inhalers not help much?
The airways are narrowed by scar tissue rather than by muscle spasm, so bronchodilators have limited effect. Some inhalers are still used to reduce inflammation and ease symptoms.
Is it the same as asthma or COPD?
No. All three cause airflow obstruction, but bronchiolitis obliterans has different causes and CT findings, and needs different monitoring and treatment.
Can it be detected early after a transplant?
Yes. Regular spirometry, sometimes with a home device, can pick up a fall in lung function before symptoms appear, allowing earlier treatment.
Is bronchiolitis obliterans contagious?
No. Although an infection can trigger it, the condition itself cannot be passed to others.
Related conditions and procedures
Consult Dr. Gogineni Ratnakara Rao
Apollo Hospitals, Financial District: Monday to Saturday, 8:30 AM to 5:00 PM. Anything in Lung Clinic, Chanda Nagar: Monday to Saturday (Thursday closed), 6:00 PM to 9:00 PM.