Respiratory bronchiolitis refers to a histological finding that can be often seen in heavy smokers.
It consists of mild chronic inflammation and accumulation of pigmented macrophages within respiratory bronchioles and related alveoli 1-2. A small amount of fibrosis in the walls of respiratory bronchioles may also be present 2 however these changes are too mild to present with symptoms (by definition).
It is closely related to respiratory bronchiolitis interstitial lung disease (RB-ILD) which represents a more advanced form of the same condition and is also seen almost exclusively amongst smokers. The occurrence of respiratory bronchiolitis in the absence of smoking is extremely uncommon, and its cause is unknown 5. Along the same spectrum of disease is also desquamative interstitial lung disease (DIP) 1 although it is not confined only to smokers.
Usually respiratory bronchiolitis has no imaging findings, although occasionally minor patchy ground glass opacities and ill-defined centrilobular nodules may be seen, which tend to be more pronounced in the upper zones 2.
History and etymology
It is thought to have been first described by D E Niewoehner et.al is 1974 3,4.
- 1. Heyneman LE, Ward S, Lynch DA et-al. Respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia: different entities or part of the spectrum of the same disease process? AJR Am J Roentgenol. 1999;173 (6): 1617-22. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Naidich David P, W. Richard Webb, Nestor L Müller et al. Computed Tomography and Magnetic Resonance of the Thorax. Fourth Edition. Lippincott Williams & Wilkins, 2007. ISBN: 0781757657.
- 3. Niewoehner DE, Kleinerman J, Rice DB. Pathologic changes in the peripheral airways of young cigarette smokers. N. Engl. J. Med. 1974;291 (15): 755-8. doi:10.1056/NEJM197410102911503 - Pubmed citation
- 4. Nakanishi M, Demura Y, Mizuno S et-al. Changes in HRCT findings in patients with respiratory bronchiolitis-associated interstitial lung disease after smoking cessation. Eur. Respir. J. 2007;29 (3): 453-61. Eur. Respir. J. (full text) - doi:10.1183/09031936.00015506 - Pubmed citation
- 5. Woo OH, Yong HS, Oh YW et-al. Respiratory bronchiolitis-associated interstitial lung disease in a nonsmoker: radiologic and pathologic findings. AJR Am J Roentgenol. 2007;188 (5): W412-4. doi:10.2214/AJR.05.0835 - Pubmed citation