The color of skin: gray diseases of the skin, nails, and mucosa.

Gray diseases are a group of skin disorders characterized mainly by gray discoloration with or without involving the mucous membranes and nails. These diseases may be hereditary or acquired. Some of the better-known hereditary entities are dermal melanocytosis, incontinentia pigmenti, hypomelanosis of Ito, hemochromatosis, ochronosis, and silvery hair syndrome. Acquired diseases with gray coloring include late-stage organ failure, lichen planus pigmentosus, erythema dyschromicum perstans, and drug reactions. The discoloration is due to either increased epidermal and or dermal melanin or dermal deposition of a chromogen or a combination of both. Investigations are directed to determining the underlying medical condition and a skin biopsy is usually unnecessary. Likewise, treatment is directed mainly toward the underlying medical disease. Although bleaching (lightening) agents may diminish the discoloration, better results may be obtained from using a Q-switched laser and intense pulsed light, either alone or in combination with topical agents.