The patient is a lifelong heavy smoker. There is no suggestion in her history of exposure or evidence of a hypersensitivity pneumonitis.

The diffuse nodules could be due to sarcoidosis, hypersensitivity pneumonitis, respiratory bronchiolitis interstitial lung disease, or even pulmonary Langerhans cell histiocytosis.

Bronchial washings returned a dark stained bronchial lavage, with heavily pigmented macrophages. This is in keeping with a diagnosis of respiratory bronchiolitis interstitial lung disease (RB-ILD).

This is a smoking related interstitial lung disease closely related to respiratory bronchiolitis, but demonstrating more severe histological, imaging and clinical findings.

Desquamative interstitial pneumonitis is also related to smoking, whether DIP and RB-ILD are part of the same disease process or seperate entities is unclear.