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.
Melanin is the pigment in skin that gives it a brown color. Hydroquinone topical (for the skin) is used to lighten areas of darkened skin such as freckles, age spots, melasma (sun damage), or chloasma (darkened skin caused by hormonal changes).