Geographic tongue is a condition that causes chronic and recurrent lesions on the tongue that resemble psoriasis of the skin. It is characterized by pink to red, slightly depressed lesions with irregular, elevated, white or yellow borders. The lesions may also occur in the mucosa of the mouth and labia; this condition is called "areata migrans" because these lesions typically disappear from one area and show up in another. The tongue is normally covered with tiny, pinkish-white bumps (papillae), which are actually short, fine, hair-like projections. With geographic tongue, patches on the surface of the tongue are missing papillae and appear as smooth, red "islands," often with slightly raised borders. These patches (lesions) give the tongue a map-like, or geographic, appearance. In most cases there are no symptoms but sometimes it is painful when inflamed.

The cause of this condition is unknown. Many researchers think it is linked with psoriasis, but more research is needed to better understand the connection. Also, hereditary and environmental factors may be involved. The condition is benign and localized, generally requiring no treatment except reassurance. If painful, it may be treated with steroid gels or antihistamine mouth rinses.