Lung - nontumor
Other interstitial pneumonitis / fibrosis
Respiratory bronchiolitis




Topic Completed: 1 September 2011

Revised: 30 January 2019, last major update September 2011

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PubMed search: respiratory bronchiolitis [title]

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Cite this page: Weisenberg E. Respiratory bronchiolitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungnontumorrespbronchiolitis.html. Accessed February 21st, 2019.
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