|Classification and external resources|
Geographic tongue, also known by several other terms, is an inflammatory condition of the mucous membrane of the tongue, usually on the dorsal surface. It is a common condition, affecting approximately 2–3% of the general population. It is characterized by areas of smooth, red depapillation (loss of lingual papillae) which migrate over time. The name comes from the map-like appearance of the tongue, with the patches resembling the islands of an archipelago. The cause is unknown, but the condition is entirely benign (importantly, it does not represent oral cancer), and there is no curative treatment. Uncommonly, geographic tongue may cause a burning sensation on the tongue, for which various treatments have been described with little formal evidence of efficacy.
Geographic tongue could be considered to be a type of glossitis. It usually presents only on the dorsal 2/3 and lateral surfaces of the tongue, but less commonly an identical condition can occur on other mucosal sites in the mouth, such as the ventral surface (undersurface) of the tongue, mucosa of the cheeks or lips, soft palate or floor of mouth; usually in addition to tongue involvement. In such cases, terms such as stomatitis erythema migrans, ectopic geographic tongue, areata migrans, geographic stomatitis, or migratory stomatitis are used instead of geographic tongue. Beside the differences in locations of presentation inside the oral cavity and prevalence among the general population, in all other aspects of clinical significance, symptoms, treatment, and histopathologic appearance, these two forms are identical.
This condition is sometimes termed (oral) erythema migrans, but this has no relation to the more common use of the term erythema migrans (erythema chronicum migrans), to describe the appearance of skin lesions in Lyme disease.
Signs and symptoms
In health, the dorsal surface of the tongue is covered in tuft like projections called lingual papillae (some of which are associated with taste buds), which give the tongue an irregular surface texture and a white-pink color. Geographic tongue is characterized by areas of atrophy and depapillation (loss of papillae), leaving an erythematous (darker red) and smoother surface than the unaffected areas. The depapillated areas are usually well demarcated, and bordered by a slightly raised, white, yellow or grey, serpiginous (snaking) peripheral zone. A lesion of geographic tongue may start as a white patch before the depapillation occurs. In certain cases there may be only one lesion, but this is uncommon; the lesions will typically occur in multiple locations on the tongue and coalesce over time to form the typical map-like appearance. The lesions usually change in shape, size and migrate to other areas, sometimes within hours. The condition may affect only part of the tongue, with a predilection for the tip and the sides of the tongue, or the entire dorsal surface at any one time. The condition goes through periods of remission and relapse. Loss of the white peripheral zone is thought to signify periods of mucosal healing.
There are usually no symptoms other than the unusual appearance of the tongue, but in some cases persons may experience pain or burning e.g. when eating hot, acidic, spicy or other kinds of foods (e.g. cheese, tomatoes, fruit). Where there is a burning symptom, other causes of a burning sensation on the tongue are considered, such as oral candidiasis.
The cause is unknown. Geographic tongue does not usually cause any symptoms, and in those cases where there are symptoms, an oral parafunctional habit may be a contributory factor. Persons with parafunctional habits related to the tongue may show scalloping on the sides of the tongue (crenated tongue). Some suggest that hormonal factors may be involved, because one reported case in a female appeared to vary in severity in correlation with oral contraceptive use. People with geographic tongue frequently claim that their condition worsens during periods of psychologic stress. Geographic tongue is inversely associated with smoking and tobacco use. Sometimes geographic tongue is said to run in families, and it is reported to be associated with several different genes, though studies show family association may also be caused by similar diets. Some have reported links with various human leukocyte antigens, such as increased incidence of HLA-DR5, HLA-DRW6 and HLA-Cw6 and decreased incidence in HLA-B51. Vitamin B2 deficiency (ariboflavinosis) can cause several signs in the mouth, possibly including geographic tongue, although other sources state that geographic tongue is not related to nutritional deficiency. Fissured tongue often occurs simultaneously with geographic tongue, and some consider fissured tongue to be an end stage of geographic tongue.
In the past, some research suggested that geographic tongue was associated with diabetes, seborrheic dermatitis and atopy, however newer research does not corroborate these findings. Some studies have reported a link between geographic tongue and psoriasis, although 90% of children who are diagnosed with geographic tongue do not develop psoriasis. Again however, modern research studies do not support any link between psoriasis and geographic tongue. Lesions that are histologically indistinguishable from geographic tongue may also be diagnosed in reactive arthritis (arthritis, uveitis/conjunctivitis and urethritis).
The differential diagnosis includes oral lichen planus, erythematous candidiasis, leukoplakia, lupus erythematosus, glossitis, and chemical burns. Atrophic glossitis is usually distinguished from benign migratory glossitis on the basis of the migrating pattern of the lesions and the presence of a whitish border, features which are not present in atrophic glossitis, which instead shows lesions which enlarge rather than migrate. Rarely, blood tests may be required to distinguish from glossitis associated with anemia or other nutritional deficiencies. Since the appearance and the history of the condition (i.e. migrating areas of depapillation) are so striking, there is rarely any need for biopsy. When biopsy is taken, the histopathologic appearance is quite similar to psoriasis:
- Subepithelial T lymphocyte inflammatory infiltrate.
- Migration of neutrophilic granulocytes into the epithelial layer, which may create superficial microabscesses, similar to the Munro's microabscesses described in pustular psoriasis.
When symptoms are present, topical anesthetics can be used to provide temporary relief. Other drugs that have been used to manage the symptoms include antihistamines, corticosteroids or anxiolytics, but these drugs have not been formally assessed for efficacy in geographic tongue. If some foods exacerbate or trigger the symptoms, then cutting these foods out of the diet may benefit. One uncontrolled trial has shown some benefit in controlling the symptoms of geographic tongue.
Geographic tongue is a common condition, affecting 2-3% of the adult general population, although other sources report a prevalence of up to 14%. It is one of the most common tongue disorders that occurs in children. The condition often starts in childhood, sometimes at an early age, but others report that the highest incidence occurs in the over 40 age group. Females are sometimes reported to be more commonly affected than males, in a 2:1 ratio, although others report that the gender distribution is equal.
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