Exogenous pigments are characterized as agents containing color that are formed outside of the body but found within tissues. Exogenous pigments can find their way into the body in a variety of ways. Examples of exogenous pigments are carbon, asbestos fibers, tattoo ink, and metals. Copper is the most commonly visualized exogenous pigment found in liver tissue. Table 3 describes some exogenous pigments found within tissues.
Table 3. Examples of Exogenous Pigments.| Exogenous Pigment | Comments |
| Copper deposits | - Accumulation found within the liver is characteristic of Wilson's disease.
- Hematoxylin and eosin (H&E) stained tissue slides commonly do not reveal the presence of copper.
- Stains such as rhodanine or rubeanic acid, shown in the image, can be used to positively identify copper in liver biopsy tissue.
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| Drug-induced deposits | - Pigment in liver tissue may be deposited from intravenous (IV) gold (used to treat rheumatoid arthritis) or illicit drug use.
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