13 Pigmented lesions
The oral mucosa is usually not very pigmented despite the fact that it has the same melanocyte density as skin. Pigmentation may be superficial (extrinsic) or intrinsic, isolated lesions or generalized, and ranges from light brown to blue-black, gray, red, or purple – the color depending on the pigment and its depth. Melanin pigment is brown, but can impart a black, brown, blue, or green color to the eye. Vascular lesions tend to be red, purple or blue, but hemorrhage can lead to red, purple, brown or other colors (Tables 13.1 and 13.2).
Superficial brown discoloration of tongue and teeth, which is easily removed and of little consequence is commonly caused by habits (e.g. cigarette smoking, tobacco or betel chewing); beverages (e.g. coffee, tea and red wine); foods (e.g. beet, liquorice); or by drugs (e.g. iron, chlorhexidine, bismuth) (Figure 13.2). Hairy tongue, often referred to as black hairy tongue, may also appear brown, white, green, or pink.