Geographic tongue, also known as Erythema Migrans or benign migratory glossitis, is of uncertain etiology. Areas of erythema with discrete white borders appear due to atrophy of the filiform papillae. Usually seen on the dorsal surface of the tongue, but other oral sites such as the buccal mucosa may be involved. Geographic tongue is associated with fissured tongue.
Assimakopoulos D, Patrikakos G, Fotika C, Elisaf M. Benign migratory glossitis or geographic tongue: an enigmatic oral lesion. Am J Med 2002;113(9):751-5.
Reamy BV, Derby R, Bunt CW. Common tongue conditions in primary care. American Family Physician. 2010;81(5):627-634.