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.
Pigmentation is the coloring of a person's skin. For various reasons, a person's skin may change color, becoming darker (hyperpigmentation) or lighter (hypopigmentation). Hyperpigmentation in skin is caused by an increase in melanin, the substance in the body that is responsible for color (pigment) and is produced by melanocytes at the lower layer of the epidermis.