Exogenous pigments - types, organ sites
Common examples of exogenous pigments are:
- Accumulation of Carbon (black), known as Anthracosis
- Commonly occurs from air pollution
- Inhaled and phagocytosed by alveolar macrophages, where it is then transported through lymph to regional tracheobronchial lymph nodes where it aggregates
- Heavy accumulation can induce emphysema or fibroblastic reaction
- Tattooing
- Pigment artificially injected into the dermal part of the skin.
- The ink particles are phagocytosed by dermal macrophages and so remain in the dermal region.
H&E, anthracosis: black carbon particles lie inside macrophages (anthracotic pigment); lymphocytes around them.
Image: “Anthracosis (5568868920)” by Yale Rosen from USA, CC BY-SA 2.0, via Wikimedia Commons.
Examples: other exogenous pigments seen in practice:
- Coal dust in coal workers' pneumoconiosis ('black lung') – heavy anthracosis with fibrosis.
- Silver – argyria: permanent slate-grey skin.
- Lead – blue-black 'lead line' along the gum margin.
- Excess dietary carotene – yellow-orange skin (palms, soles) with white sclerae, unlike jaundice.