DEFINITION- Leukoplakia (white plaque) may be clinically
defined as a white patch or plaque on the oral mucosa, exceeding 5 mm in diameter, which cannot be rubbed off nor can be classified into any other diagnosable disease.

–the term ‘leukoplakia’ is reserved for epithelial thickening which may range from completely benign to atypical and to premalignant cellular changes.

INCIDENCE–

1. It occurs more frequently in males than
females.

2.The lesions may be of variable size and appearance.

3. The sites of predilection, in descending orderof frequency, are: cheek mucosa, angles of mouth, alveolar mucosa, tongue, lip, hard and soft palate, and floor of the mouth.

4.In about 4-6% cases of leukoplakia, carcinomatous
change is reported.

ETIOLOGY-

1. It has the strongest association with the use of tobacco in various forms, e.g. in heavy smokers (especially in pipeand cigar smokers) and improves when smoking is discontinued, and in those who chew tobacco as in paan, paan masaala, zarda, gutka etc.

2.The condition is also known by other names such as smokers keratosis and stomatitis nicotina.

3. Other etiological factors implicated are chronic friction such as with ill-fitting dentures or jagged teeth, and local irritants like excessive consumption of alcohol and very hot and spicy foods and beverages.

4. A special variety of leukoplakia called ‘hairy leukoplakia’ has
been described in patients of AIDS and has hairy or corrugated surface but is not related to development of
oral cancer.

MORPHOLOGIC FEATURES.

1.Grossly, the lesions of leukoplakia may appear white, whitish-yellow, or redvelvety of more than 5 mm diameter and variable in appearance.

2. They are usually circumscribed, slightly elevated, smooth or wrinkled, speckled or nodular.

Histologically, leukoplakia is of 2 types:

1. The hyperkeratotic type- This is characterised by an orderly and regular hyperplasia of squamous epithelium with hyperkeratosis on the surface.

2. Dysplastic type- When the changes such as irregular stratification of the epithelium, focal areas of increased and abnormal mitotic figures, hyperchromatism, pleomorphism, loss of polarity and individual cell keratinisation are present, the lesion is considered as epithelial dysplasia

-The subepithelial tissues usually show an inflammatory infiltrate composed of lymphocytes and plasma cells.

– The extent and degree of the epithelial changes indicate the degree of severity of the epithelial dysplasia.

-Usually, mild dysplasia may revert back to normal if the offending etiologic factor is removed, whereas severe dysplasia indicates that the case may progress to carcinoma.

source – textbook of pathology for dental students harsh mohan