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 Changes in Dark Skin. In hyperpigmentation, the skin either produces too much pigment or the pigment is deposited deep within the skin, resulting in dark spots. When color is lost, it's called hypopigmentation, which results in light-colored patches. All people with dark skin are at risk for both skin conditions.