Histopathologic Features of Chronic Obstructive Pulmonary Disease Emphysema Proximal acinar emphysema * Destruction of respiratory bronchioles with relative sparing of distal alveoli Panacinar emphysema * Destruction of respiratory bronchioles through to terminal alveoli Alteration of Respiratory (smoker's) bronchiolitis the airways Inflammation and fibrosis of terminal and respiratory bronchioles Reduction in terminal bronchioles Goblet cell metaplasia Squamous metaplasia Alteration of Intimal thickening with smooth muscle the vasculature proliferation and elastin/collagen deposition Smooth muscle hyperplasia of the media
First-generation respiratory bronchiole with macrophages within the airway lumen and also within the adjacent alveolar airspaces (hematoxylin-eosin, original magnification x4.
The lesion consists of sharply circumscribed areas containing a mixture of emphysema and dense, distinctively hyaline paucicellular interstitial fibrosis that often appears to radiate from the region of a respiratory bronchiole
to the pleura (Figure 1, A).
Also includes perivascular adventitia and lymphatic capillaries surrounding pulmonary arterioles, veins, and venules not associated with conducting airways or respiratory bronchioles 8.
One broader anatomic compartment was referred to as parenchymal lumens and consisted of lumens of alveolar ducts and alveoli in rats and lumens of respiratory bronchioles, alveolar ducts, and alveoli in humans.
No more than 2% of the retained material was in the lumens of respiratory bronchioles and conducting airways (combined).
Variably extensive and variably severe inflammatory and fibrotic changes caused by tobacco smoke that are found in the terminal bronchioles and respiratory bronchioles
are termed, respectively, membranous bronchiolitis and respiratory bronchiolitis.
In this paper, we report evidence that both carbonaceous and mineral dust are primarily distributed to the terminal and respiratory bronchioles and that there is anatomical remodeling within these same sites.
We also sampled parenchymal tissues and associated terminal and respiratory bronchioles were also sampled beyond the 12th airway generation of each airway path that was microdissected.
Grading of Severity of Fibrosis for Asbestosis Cases Grade 0 No appreciable peribronchiolar fibrosis, or less than half of bronchioles involved Grade 1 Fibrosis confined to the walls of respiratory bronchioles
and the first adjacent tier of adjacent alveoli, with involvement of more than half of all bronchioles on a slide Grade 2 Extension of fibrosis to involve alveolar ducts and/or 2 or more tiers of alveoli adjacent to the respiratory bronchiole
, with sparing of at least some alveoli between adjacent bronchioles Grade 3 Fibrotic thickening of the walls of all alveoli between at least 2 adjacent respiratory bronchioles
Grade 4 Honeycomb changes Table 2.
Some, such as Ryu et al, (6) appear to accept cases with nothing more than smoker's macrophages (albeit this report does not provide pathologic details), but most authors have noted that the walls of the respiratory bronchioles are fibrotic in RBILD and may also contain inflammatory cells, (1,4,5,7,8) and most have also included fibrosis and inflammation in the alveolar walls surrounding respiratory bronchioles as part of the morphologic spectrum of this disease.
This paradigm suggested that any or all of the small cartilaginous airways and membranous or respiratory bronchioles were structurally altered (remodeled in current COPD terminology) in cigarette smokers and that this remodeling induced turbulent flow and increased airway resistance despite the large cross-sectional area of the airways involved.