Lung - nontumor
Other interstitial pneumonitis / fibrosis
Respiratory bronchiolitis

Author: Elliot Weisenberg, M.D. (see Authors page)

Revised: 1 March 2017, last major update September 2011

Copyright: (c) 2003-2017,, Inc.

PubMed search: respiratory bronchiolitis [title]

Cite this page: Respiratory bronchiolitis. website. Accessed November 17th, 2018.
Definition / general
  • Common, almost always seen in cigarette smokers generally with 30+ pack year history
  • May persist 5 years or more after quitting, often incidental finding (Am J Surg Pathol 2002;26:647)
  • May cause cough and dyspnea, usually mild, which regresses after cigarette cessation
  • Severe disease known as respiratory bronchiolitis associated interstitial lung disease
Microscopic (histologic) description
  • Focal chronic inflammation of terminal bronchioles and alveolar ducts with adjacent focal interstitial inflammation and fibrosis
  • Histiocytes fill alveolar ducts and spaces, but are predominantly peribronchiolar
  • Histiocyte cytoplasm contains brown / black / yellow granules (smoker's granules)
Differential diagnosis
  • DIP: no pigmented macrophages