Lung - Foreign Material
comment:Foreign material ( Figure 1 , Figure 2 , Figure 3 , and Figure 4 ) refers to inhaled test material or presumed test material. The term "pigmentation" is reserved for endogenous pigments (hemosiderin, lipofuscin) found in the lung and should not be used for exogenous material. If the material has the expected morphologic appearance, is found only in treated animals, and increases in amount with increasing exposure level, it may be assumed to be the test agent. The term "foreign body" is reserved for inhaled bits of plant material (feed or bedding), hair fragments, corn oil from gavage accidents, or other substances that are not found only in the treated animals or do not increase in severity with increasing exposure level.
The response to inhaled test material varies from histiocyte infiltration with relatively inert material to a more severe inflammatory reaction that may be acute (in short-term studies), chronic active, chronic, or granulomatous, depending on the physicochemical properties of the foreign material. Other lesions may be associated with an inflammatory response, such as alveolar proteinosis, necrosis, fibrosis, or epithelial hyperplasia of the airways and/or alveoli.
recommendation:Lung - Foreign material (inhaled test material or presumed test material) should be diagnosed and graded whenever present. The specific location (e.g., alveolus, bronchus, or bronchiole) should be indicated in the diagnosis as a site modifier. If the foreign material is present in more than one location, the site modifier may be omitted and the locations described in the pathology narrative. Associated lesions (e.g., histiocytic infiltration, inflammation, necrosis, fibrosis, epithelial hyperplasia) should be diagnosed and graded separately.
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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.
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