Small Airways Disease

This bronchiole is taken from the lung of the patient with aspergillosis, who underwent lung volume reduction surgery. Compare it with the normal bronchiole shown below with respect to:

  • Luminal content
  • Epithelium
  • Mural changes


Small airways disease involves membranous bronchioles, <2 mm in diameter, and respiratory bronchioles. Histologic abnormalities have been graded and scores summed to give a pathologic score that has been shown to correlate with decline in FEV1. Abnormalities include: epithelial erosions, smooth muscle hyperplasia, fibrosis, mural inflammation, luminal exudate, deformity, decreased numbers of alveolar wall attachments, and an increased percentage of airways <400 µm in diameter [1].


1. Saetta M, Finkelstein R, Cosio M. Morphological and cellular basis for airflow limitation in smokers. Eur Respir J 1994; 7:1505-1515.


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Small airways disease

Chronic bronchiolitis

Luminal content: The lumen is filled with a mucous plug.

Epithelium: The epithelium is taller than normal and, although not seen at this power, shows goblet cell metaplasia, which is not normally present in bronchioles.

Mural changes: The wall shows fibrous thickening and increased prominence of smooth muscle (arrows indicate its thickness). Although not evident in the photo, the alveolar attachments to the bronchiolar wall are probably decreased in number.

Normal bronchiole

The normal bronchiole has a patent lumen, cuboid epithelium, a thin fibromuscular wall and multiple alveolar attachments.



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