Obliterative bronchiolitis (OB), also known as bronchiolitis obliterans or constrictive bronchiolitis, is a type of bronchiolitis and refers to bronchiolar inflammation with submucosal peribronchial fibrosis associated with luminal stenosis and occlusions. OB should not be confused with bronchiolitis obliterans organizing pneumonia (BOOP).
Recognized associations include:
- inflammatory bowel disease
- rheumatoid arthritis: considered the commonest connective tissue disease to be associated with obliterative bronchiolitis
- medications, e.g. penicillamine
- as a complication following lung transplantation: post lung transplant bronchiolitis obliterans ; can occur in up to 10% of patients, usually within 6-12 months following bone marrow transplantation
- Swyer-James syndrome
Its cardinal features are progressive breathlessness and a dry cough .
The condition is characterized by concentric luminal narrowing of the membranous and respiratory bronchioles as a result of submucosal and peribronchiolar inflammation and fibrosis without any intraluminal granulation tissue or polyps/polyposis. There is an absence of diffuse parenchymal inflammation.
It can result from number of causes:
- post viral (e.g. adenovirus)
- post atypical infection (e.g. Mycoplasma pneumonia)
- noxious fume inhalation
- neuroendocrine hyperplasia (pulmonary tumourlets)
- post-transplant patients
Chest radiographic findings can be normal or, if abnormal, non-specific. Some associated features include:
- attenuation of vascular markings
- occasionally reticular/reticulonodular markings
On HRCT chest, there are often sharply defined, areas of decreased lung attenuation associated with vessels of reduced caliber. These changes represent a combination of air trapping and oligemia. This combination can give a mosaic attenuation pattern. Other features include:
History and etymology
It was first described by the French physician AC Reynaud in 1835 .