http://www.emedicine.com/derm/topic664.htmBackground: Geographic tongue (benign migratory glossitis) is a benign condition that occurs in up to 3% of the general population. Most often, it is asymptomatic; however, some patients report increased sensitivity to hot and spicy foods. The etiology and the pathogenesis are still poorly understood. The condition affects males and females and is noted to be more prominent in adults than in children.
Classically, it appears as an area of erythema, with atrophy of the filiform papillae of the tongue, surrounded by a serpiginous, white, hyperkeratotic border. The patient often reports spontaneous resolution of the lesion in one area, with the return of normal tongue architecture, only to have another lesion appear in a different location of the tongue. Lesion activity may wax and wane over time, and patients are occasionally free of lesions. If lesions occur at other mucosal sites, the condition is termed erythema migrans.
Pathophysiology: The most commonly affected site is the tongue; however, other oral mucosal soft tissue sites may be affected. It has been reported with increased frequency in patients with psoriasis and in patients with fissured tongue. Although this is an inflammatory condition histologically, a polygenic mode of inheritance has been suggested because it is seen clustering in families. Associations with human leukocyte antigen DR5 (HLA-DR5), human leukocyte antigen DRW6 (HLA-DRW6), and human leukocyte antigen Cw6 (HLA-Cw6) have also been reported.