Definition of Geographic tongue:

Geographic tongue is a map-like appearance of your tongue due to irregular patches on its surface.

Causes, incidence, and risk factors:

The specific cause of geographic tongue is unknown, although vitamin B deficiency may be involved. Other causes may include irritation from hot or spicy foods, or alcohol. The condition appears to be less common in those who smoke.

The pattern on the surface of the tongue may change very rapidly. This pattern changes occur when there is a loss of the tiny finger-like projections, called papillae, on the tongue's surface. This makes areas of the tongue flat. These areas are said to be "denuded." Denuded areas may persist for more than a month.