Respiratory bronchiolitis-interstitial lung disease

Last revised by Liz Silverstone on 6 Aug 2023

Respiratory bronchiolitis interstitial lung disease (RB-ILD) is the symptomatic form of smoking related interstitial lung disease in the same spectrum as respiratory bronchiolitis (RB), but demonstrating more severe histological findings. On CT, the appearances should be reported as RB.

In almost all cases, respiratory bronchiolitis-interstitial lung disease is associated with heavy tobacco smoking (usually 30 pack-years or more) and is often seen in 30-40 years age group.

Chronic cough and progressive dyspnea 4 differentiate RB-ILD from RB. Inspiratory crackles are heard in up to half of patients. Clubbing is rare 1. RB-ILD is a clinical diagnosis.

On lung biopsy of respiratory bronchiolitis-interstitial lung disease, pigment-laden macrophages are found within alveoli, and peribronchial inflammation noted. Unlike simple respiratory bronchiolitis, fibrosis extends beyond the tissues immediately adjacent to respiratory bronchioles and extends into alveolar septae.

Histologically respiratory bronchiolitis-interstitial lung disease is very similar to desquamative interstitial pneumonia (DIP) and many authors feel that the two conditions are closely related, or even variants of the same condition 3. It has even been suggested that DIP should be abolished altogether, and simply thought of as end-stage/severe RB-ILD 5.

  • ground glass opacities: may have a slight upper zone predilection 9

  • poorly defined centrilobular nodules

  • no particular distribution with both upper and lower zones potentially affected

  • if advanced, fibrosis may be evident typically affecting the subpleural regions and more so in the lower lung zones

  • patchy areas of hypoattenuation (~40%) with a lower lung predominance 10

  • other changes related to smoking

Usually, no treatment is required for respiratory bronchiolitis-interstitial lung disease other than giving up smoking.

It was first described in 1974 by the American pulmonologist Dennis E Niewoehner (1940-2020) 15 and colleagues 11,13.

With typical HRCT chest appearances consider:

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Cases and figures

  • Case 1
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  • Case 1: CT 2 months later
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