The term leukoplakia (Greek, “white patch”) is defined by the World Health Organisation as “a white plaque / patch, firmly attached to the oral mucosa, that cannot be rubbed off or clinically identified as another named entity”. It is therefore strictly a clinical label rather than a histological diagnosis.
Leukoplakias should be biopsied, after which a more definitive diagnosis can be assigned. Most prove to be benign (usually hyperkeratosis or chronic inflammation), however, up to 20% may exhibit histological changes consistent with dysplasia or carcinoma. They should therefore be regarded with suspicion until proven otherwise, particularly if occurring in a high-risk site such as the ventral or lateral tongue or floor of mouth.
The clinical appearance is extremely variable with respect to size, shape, thickness, and homogeneity of colour. They are usually asymptomatic.
The exact ætiology remains unknown. Tobacco, alcohol, chronic local friction, betel use; sanguinarine use and Candida albicans are important predisposing factors. Others include Epstein Bar Virus and Syphilis. These latter carry a higher risk of malignant transformation.
Occurs in approx 1% of the population; men > women
Three clinical varieties are recognised:
- homogeneous (common; faintly white – very thick & opaque)
- speckled (less common; non-homogenous / heterogenous leukoplakias has a high risk of malignant transformation) and
- verrucous (rare).
The buccal mucosæ, tongue, floor of the mouth, gingivæ and lower lip are the most commonly affected sites. However, leukoplakias found in the soft palate complex, on ventro-lateral aspects of the tongue & the floor of mouth have a high risk of malignant transformation. The malignant potential depends on appearance, site & some ætiological factors.
The following conditions should be considered before making a diagnosis of leukoplakia:
- Elimination or discontinuation of pre-disposing factors (such as tobacco or betel nut)
- Surgical excision is the treatment of choice
- Medical treatment entails the use of anti-inflammatories or anti fungals; topical anti-cancer drugs or retinoid compounds. These cause regression of the leukoplakias but their efficacy is temporary.
- Chemo-prevention, which prevents leukoplakias from becoming malignant, entail the use of retinoids (such as 13-cis-retinoic acid and fenretinide). However, problems with side-effects, lack of availability and recurrence limits their use.
- Lesions removed followed by regular follow-ups.