Last reviewed 01/2018
The term Bronchiolitis obliterans may be used in different ways either to describe a histological appearance or to describe a clinical syndrome.
When used to describe a histological appearance it refers to the histological appearance of a polypoid plug of granulation tissue in the lumen of terminal and respiratory bronchioles. This is a non-specific finding and may occur in most infectious pneumonias, following diffuse alveolar damage, aspiration and cryptogenic organising pneumonia.
When used to describe a clinical syndrome it usually implies a chronic scarring process as opposed to a potentially reversible granulating process. It usually affects the small airways of the lung resulting in progressive obliteration of the smaller airways and obstructive lung disease.