Lung - Fibrosis

Lung - Fibrosis in a mouse. The airspaces have been obliterated at the tip of the lung lobe (arrow).
Figure 1 of 8

Lung - Fibrosis in a mouse (same animal as in Figure 1). The blue staining indicates interstitial fibrosis. Masson�s trichrome stain.
Figure 2 of 8

Lung - Fibrosis in a male F344/N rat from a chronic study. Severe interstitial fibrosis replaces the lung parenchyma.
Figure 3 of 8

Lung, Bronchiole - Fibrosis in a female F344/N rat in a subchronic study. There is intraluminal and mural bronchiolar fibrosis.
Figure 4 of 8

Lung, Bronchus - Fibrosis in a male B6C3F1/N mouse from a chronic study. There is multifocal subepithelial bronchial fibrosis (arrow).
Figure 5 of 8

Lung, Bronchus - Fibrosis in a male B6C3F1/N mouse from a chronic study (higher magnification of Figure 5). There is a focus of mature subepithelial bronchial fibrosis with epithelial atrophy.
Figure 6 of 8

Lung, Pleura - Fibrosis in a female B6C3F1/N mouse from a chronic study. The pleura is thickened by fibrosis and inflammation.
Figure 7 of 8
comment:
Fibrosis appears microscopically as an increase in the amount of fibrous tissue that either replaces or expands normal structures. Fibrosis can occur anywhere in the lung, including alveolar septa or interstitium ( Figure 1










recommendation:
Lung - Fibrosis should be diagnosed and graded whenever present. The location of the fibrosis (alveolus, bronchus/bronchiole, pleura) should be included in the diagnosis as a site modifier. The preferred terminology for fibrosis involving the interalveolar septa (alveolar walls) is Lung, Interstitium - Fibrosis. If fibrosis occurs in conjunction with inflammation, it should be diagnosed separately, though if the degree of fibrosis is very minimal or sporadic (occurring in only a few animals), it may be described in the pathology narrative in lieu of a separate diagnosis.references:
Boorman GA, Eustis SL. 1990. Lung. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 339-367.
Dixon D, Herbert RA, Sills RC, Boorman GA. 1999. Lungs, pleura, and mediastinum. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 293-332.
Renne RA, Dungworth DL, Keenan CM, Morgan KT, Hahn FF, Schwartz LW. 2003. Non-proliferative lesions of the respiratory tract in rats. In: Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC.
Web page last updated on: December 07, 2015