Leukoplakia: white and precancerous lesion
Leukoplakia is a clinical term & a precancerous lesion. (leuko=white, plakia=patch)
The lesion is defined as a white patch or plaque, firmly attached to the oral mucosa, can`t be rubbed off & that cannot be classified as any other disease entity.
- The exact etiology remains unknown. Tobacco, alcohol, chronic local friction, and Candida albicans are important predisposing factors.
- Human papilloma virus (HPV) may also be involved in the pathogenesis of oral leukoplakia.
- Mechanical factors: low grade continuous trauma by sharp teeth, ill-fitting denture
Types: Three clinical varieties are recognized:
2.speckled (less common)
- Age- usually in elderly & middle age
- Sex- male
- Site- The buccal mucosa, tongue, floor of the mouth, gingiva, and lower lip are the most commonly affected sites.
- Tough, adherent and can`t wipped up
- Surface is irregular and raised above the mucosa or surrounding margin
- Speckled and verrucous leukoplakia have a greater risk for malignant transformation than the homogeneous form.
- The average percentage of malignant transformation for leukoplakia varies between 4% and 6%.
Ranking of leukoplakia probability related to occurrence and probability of leukoplakia representing dysplasia, by location
|Occurrence||Probability of dysplasia|
|1. Buccal mucosa
2. Mandibular vestibule
3. Maxillary gingiva
4. Mandibular gingiva
6. Floor of the mouth
7. Lower lip
|1. Floor of the mouth
3. Lower lip
4. Mandibular gingiva
5. Buccal mucosa
6. Mandibular vestibule
7. Maxillary gingiva
Lesions demonstrate a spectrum of histologic change within stratified squamous epithelium, ranging from simple hyperorthokeratosis to hyperparakeratosis and/or acanthosis to defective maturation. The latter changes may be minimal (mild epithelial dysplasia), moderate, or extensive (severe epithelial dysplasia or carcinoma in situ). Because there are no clearly defined histologic criteria to distinguish these groups, there may be considerable variation in diagnosis.
Normal stratified squamous epithelium shows a smooth progression from cuboidal or columnar basal cells through polygonal prickle cells, which flatten as they approach the surface. Thus cells at any given level resemble their neighbors, and the epithelium tends to have a horizontal orientation.(fig)
A dysplastic epithelium, however, will often lose this stratification or polarity as the cells become elongated and appear to stream in a more vertical direction. (Figs)
A dysplastic epithelium will also lose its harmonious, orderly stratification, a feature that can be appreciated at low magnification.(Fig)
The overall appearance may indicate hyperplasia and/or atrophy, but in either case there is often the formation of drop-shaped rete ridges. (Fig) Other distortions of the normal contour of the rete ridges may also occur.
- Lichen planus,
- cinnamon contact stomatitis,
- hairy leukoplakia,
- lichen planus reactions,
- chronic biting,
- tobacco pouch keratosis,
- chemical burn,
- uremic stomatitis,
- skin graft,
- some genodermatoses and
- discoid lupus erythematosus.
It representing benign hyperkeratosis require only continued follow-up and an effort to eliminate any possible causative agents. Cases that show only mild dysplasia are believed to be reversible. Leukoplakias, which is graded as moderate dysplasia to carcinoma in situ, require excision of the entire lesion with a 1-cm margin, regardless of size. The excisional depth should extend into the submucosa, maximizing the possibility of removing a lesion before invasion occurs and gaining a tumor-free margin if an area has just started an invasive pattern. This improves the eventual prognosis and could obviate the need for much more disfiguring and complex surgery or radiotherapy later. If at all possible, the resultant wound should be closed primarily by reasonable advancement of tissues. If it cannot be closed, a split-thickness skin graft for cover may be needed, or the wound may need to be allowed to granulate and then covered by secondary epithelialization.