Table 5.

Characteristic pathology findings of bronchiolitis obliterans disease from acute irritant gas exposures.

Low acute doses (not sufficient to denude bronchiolar epithelium):

With infrequent exposures, e.g., 2 week intervals⿿Normal healing and replacement of bronchiolar epithelium

With frequent exposures, e.g., daily⿿Remodeling of more sensitive cell types (e.g., clara cells) to less sensitive types

Threshold-dependent responses (doses sufficient to denude bronchiolar epithelium)

Severe bronchiolar inflammatory response

Cytotoxicity with severe basement membrane damage

Severe neutrophilic infiltration

DNA-alkylation and stunted healing and remodeling

Possible longer-term responses (without timely steroid and antibiotic therapy):

Widespread concentric bronchiolar fibrosis

Possible chronic bronchitis (purulent) from repeated infection

Possible bronchiectasis (in addition to concentric fibrosis) from repeated/chronic infection