Leukoplakia

Leukoplakia - leukokeratosis, manifested in the form of milky-white spots on the mucous membranes covered with multilayered flat epithelium (oral cavity, vagina, red border of the lips), develops as a result of exposure to local irritants, as well as inflammatory phenomena. There are three clinical varieties of leukoplakia: flat, warty and erosive-ulcerative.

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Flat leukoplakia

Flat leukoplakia is characterized by sharply defined, grayish-white keratinized areas of varying size and shape, usually without compaction, not rising above the surrounding mucous membrane, and difficult to remove mechanically. Histological examination reveals acanthosis with parakeratosis at the sites of the lesion, and edema with the presence of merging perivascular polymorphic cellular infiltrates in the stroma.

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Verrucous leukoplakia

The warty form of leukoplakia is a plaque-like, tuberous or warty foci of gray-white color, slightly dense, protruding above the surrounding mucous membrane, sometimes developing on the background of flat leukoplakia. Histologically, pronounced hyperkeratosis is detected without loosening of the stratum corneum, the granular layer consists of 3-6 rows of cells with well-defined granularity, acanthosis with uneven epidermal outgrowths. The outgrowths of the spinous layer are thickened, in some groups of cells - intracellular edema. In the dermis - edema, vasodilation and perivascular lymphocytic infiltrates. On the mucous membrane of the cheeks, parakeratosis is most often noted, sometimes hyperkeratosis, exocytosis and more pronounced infiltrates in the stroma.

Erosive ulcerative leukoplakia

The erosive-ulcerative form of leukoplakia is clinically characterized by the presence of single or multiple erosions of varying sizes, usually occurring against the background of keratinized foci of flat leukoplakia. Histological examination reveals an epithelial defect, along the edges of which acanthosis with elongation of epithelial outgrowths, parakeratosis and exocytosis are found. In the stroma, there are pronounced inflammatory changes, accompanied by hyperemia and edema, as well as the appearance of diffuse infiltrates of lymphocytes with an admixture of plasma cells and tissue basophils.

A. Burkhardt and G. Seifert (1977) differentiate benign, precancerous and cancerous forms of leukoplakia. In the benign form of leukoplakia, acanthosis, hyperkeratosis and a clear basement membrane are found; cellular atypia is absent. Inflammatory phenomena are weakly expressed. Precancerous changes in the epithelium of the mucous membrane in leukoplakia go through three stages. In stage I, discomplexation is noted in the basal and suprabasal layers of the epidermis with insignificant cellular atypia. In stage II, the spread of foci of atypia throughout the entire thickness of the epidermis with dyskeratosis and pronounced parakeratosis is observed. In stage III, the epithelium sharply thickens (acanthosis), cell polymorphism, dyskeratosis and parakeratosis with foci of erosion are expressed. Accordingly, inflammatory phenomena intensify, accompanied by dense infiltration of lymphocytes with an admixture of plasma cells and numerous Russell bodies.

Differentiating benign and precancerous leukoplakia is very difficult, as there are often transitional forms between them. Differential diagnosis should also be made with benign reactive epidermal hyperplasia, for example, in candidiasis of the oral mucosa.

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