Leukoplakia
Oral leukoplakia is a potentially malignant disorder affecting the oral mucosa. It is defined as "essentially an oral mucosal white/gray lesion that cannot be considered as any other definable lesion." Oral leukoplakia is a gray patch or plaque that develops in the oral cavity and is strongly associated with smoking. Leukoplakia is a firmly attached white patch on a mucous membrane which is associated with increased risk of cancer. The edges of the lesion are typically abrupt and the lesion changes with time. Advanced forms may develop red patches. There are generally no other symptoms. It usually occurs within the mouth, although sometimes mucosa in other parts of the gastrointestinal tract, urinary tract, or genitals may be affected.
The cause of leukoplakia is unknown. Risk factors for formation inside the mouth include smoking, chewing tobacco, excessive alcohol, and use of betel nuts. One specific type is common in HIV/AIDS. It is a precancerous lesion, a tissue alteration in which cancer is more likely to develop. The chance of cancer formation depends on the type, with between 3–15% of localized leukoplakia and 70–100% of proliferative leukoplakia developing into squamous cell carcinoma.
Leukoplakia is a descriptive term that should only be applied after other possible causes are ruled out. Tissue biopsy generally shows increased keratin build up with or without abnormal cells, but is not diagnostic. Other conditions that can appear similar include yeast infections, lichen planus, and keratosis due to repeated minor trauma. The lesions from a yeast infection can typically be rubbed off while those of leukoplakia cannot.
Treatment recommendations depend on features of the lesion. If abnormal cells are present or the lesion is small surgical removal is often recommended; otherwise close follow up at three to six month intervals may be sufficient. People are generally advised to stop smoking and limit the drinking of alcohol. In potentially half of cases leukoplakia will shrink with stopping smoking; however, if smoking is continued up to 66% of cases will become more white and thick. The percentage of people affected is estimated at 1–3%. Leukoplakia becomes more common with age, typically not occurring until after 30. Rates may be as high as 8% in men over the age of 70.Classification
Leukoplakia could be classified as mucosal disease, and also as a premalignant condition. Although the white color in leukoplakia is a result of hyperkeratosis, similarly appearing white lesions that are caused by reactive keratosis are not considered to be leukoplakias. Leukoplakia could also be considered according to the affected site, e.g. oral leukoplakia, leukoplakia of the urinary tract, including bladder leukoplakia or leukoplakia of the penis, vulvae, cervix or vagina. Leukoplakia may also occur in the larynx, possibly in association with gastro-esophageal reflux disease. Oropharyngeal leukoplakia is linked to the development of esophageal squamous cell carcinoma, and sometimes this is associated with tylosis, which is thickening of the skin on the palms and soles of the feet. Dyskeratosis congenita may be associated with leukoplakia of the oral mucosa and of the anal mucosa.Mouth
Within the mouth, leukoplakia is sometimes further classified according to the site involved, e.g. leukoplakia buccalis or leukoplakia lingualis. There are two main clinical variants of oral leukoplakia, namely homogeneous leukoplakia and non-homogeneous leukoplakia, which are described below. The word leukoplakia is also included within the nomenclature of other oral conditions which present as white patches, however, these are specific diagnoses that are generally considered separate from leukoplakia, with the notable exception of proliferative verrucous leukoplakia, which is a recognized sub-type of leukoplakia.Homogeneous leukoplakia
Homogeneous leukoplakia is usually well defined white patch of uniform, flat appearance and texture, although there may be superficial irregularities. Homogeneous leukoplakia is usually slightly elevated compared to surrounding mucosa, and often has a fissured, wrinkled or corrugated surface texture, with the texture generally consistent throughout the whole lesion. This term has no implications on the size of the lesion, which may be localized or extensive. When homogeneous leukoplakia is palpated, it may feel leathery, dry, or like cracked mud.Non-homogeneous leukoplakia
Non-homogeneous leukoplakia is a lesion of non-uniform appearance. The color may be predominantly white or a mixed white and red. The surface texture is irregular compared to homogeneous leukoplakia, and may be flat, nodular or exophytic. "Verrucous leukoplakia" is a descriptive term used for thick, white, papillary lesions. Verrucous leukoplakias are usually heavily keratinized and are often seen in elderly people. Some verrucous leukoplakias may have an exophytic growth pattern, and some may slowly invade surrounding mucosa, when the term proliferative verrucous leukoplakia may be used. Non-homogeneous leukoplakias have a greater risk of cancerous changes than homogeneous leukoplakias.Proliferative verrucous leukoplakia
Proliferative verrucous leukoplakia is a recognized high risk subtype of non-homogeneous leukoplakia. It is uncommon, and usually involves the buccal mucosa and the gingiva. This condition is characterized by extensive, papillary or verrucoid keratotic plaques that tends to slowly enlarge into adjacent mucosal sites. An established PVL lesion is usually thick and exophytic, but initially it may be flat. Smoking does not seem to be as strongly related as it is to leukoplakia generally, and another dissimilarity is the preponderance for women over 50. There is a very high risk of dysplasia, transformation to squamous cell carcinoma with high mortality.Erythroleukoplakia
Erythroleukoplakia is a non-homogeneous lesion of mixed white and red color. Erythroplakia is an entirely red patch that cannot be attributed to any other cause. Erythroleukoplakia can therefore be considered a variant of either leukoplakia or erythroplakia since its appearance is midway between. Erythroleukoplakia frequently occurs on the buccal mucosa in the commissural area as a mixed lesion of white nodular patches on an erythematous background, although any part of the mouth may be affected. Erythroleukoplakia and erythroplakia have a higher risk of cancerous changes than homogeneous leukoplakia.Sublingual keratosis
Sometimes leukoplakia of the floor of mouth or under the tongue is called sublingual keratosis,. though this is not universally accepted to be a distinct clinical entity from idiopathic leukoplakia generally, as it is distinguished from the latter by location only. Usually sublingual keratoses are bilateral and possess a parallel-corrugated, wrinkled surface texture described as "ebbing tide".Candidal leukoplakia
Candidal leukoplakia is usually considered to be a largely historical synonym for a type of oral candidiasis, now more commonly termed chronic hyperplastic candidiasis, rather than a subtype of true leukoplakia. However, some sources use this term to refer to leukoplakia lesions that become colonized secondarily by Candida species, thereby distinguishing it from hyperplastic candidiasis.is a corrugated white lesion on the sides of the tongue caused by opportunistic infection with Epstein-Barr virus on a systemic background of immunodeficiency, almost always human immunodeficiency virus infection. This condition is not considered to be a true idiopathic leukoplakia since the causative agent has been identified. It is one of the most common oral lesions associated with HIV infection, along with pseudomembraneous candidiasis. The appearance of the lesion often heralds the transition from HIV to acquired immunodeficiency syndrome.Syphilitic leukoplakia
This term refers to a white lesion associated with syphilis, specifically in the tertiary stage of the infection. It is not considered to be a type of idiopathic leukoplakia, since the causative agent Treponema pallidum is known. It is now rare, but when syphilis was more common, this white patch usually appeared on the top surface of the tongue and carried a high risk of cancerous changes. It is unclear if this lesion was related to the condition itself or whether it was caused by the treatments for syphilis at the time.Esophagus
Leukoplakia of the esophagus is rare compared to oral leukoplakia. The relationship with esophageal cancer is unclear because the incidence of esophageal leukoplakia is so low. It usually appears as a small, nearly opaque white lesion that may resemble early esophageal squamous cell carcinoma. The histologic appearance is similar to oral leukoplakia, with hyperkeratosis and possible dysplasia.Bladder
In the context of lesions of the mucous membrane lining of the bladder, leukoplakia is a historic term for a visualized white patch which histologically represents keratinization in an area of squamous metaplasia. The symptoms may include frequency, suprapubic pain, hematuria, dysuria, urgency, and urge incontinence. The white lesion may be seen during cystoscopy, where it appears as a whitish-gray or yellow lesion, on a background of inflamed urothelium and there may be floating debris in the bladder. Leukoplakia of the bladder may undergo cancerous changes, so biopsy and long term follow up are usually indicated.Anal canal
Leukoplakia of the anal canal is rare. It may extend up to the anorectal junction. On digital examination it feels hard and granular, and at proctoscopy, it appears as white plaques which may be diffuse, circumferential, or circumscribed. The histologic appearance is similar to oral leukoplakia, with hyperkeratosis and acanthosis. It may be asymptomatic, with symptoms due to other lesions such as hemorrhoids or fissures. Progression to anal stenosis has been described. The malignant potential is seemingly low, and few cases of anal carcinoma have been reported associated with anal leukoplaka.