Carpal Tunnel Syndrome And Tarsal Tunnel Syndrome Carpal tunnel syndrome is a condition in which irritation of the wrist's median nerve causes tingling and numbness of the thumb,...learn more Â». In This Article.
1 Argyria-characterised by a metallic, slate-grey or blue-grey pigmentation. 2  The hyperpigmentation is most apparent in the UV-exposed areas of skin, especially the forehead, nose, and hands, as well as mucous membranes. 3  Argyria results from prolonged contact with or ingestion of silver salts.
Eumelanin is a dark pigment that predominates in black and brunette hair. There are two different types of eumelanin (brown eumelanin and black eumelanin). A small amount of brown eumelanin in the absence of other pigments apparently causes blond hair. Pheomelanin is a lighter pigment found in red hair, and is concentrated in the redder areas of the skin such as the lips.