Leukoplakia is a lesion of the mucous membrane, manifested by focal keratinization of the multilayer flat epithelium. The keratin color of the keratinized epithelium causes the white or grayish color of the foci of leukoplakia. The disease occurs on the mucous membrane of the oral cavity, respiratory tract, urine-genital organs, in the anal area. Disease refers to precancerous diseases and can undergo malignant degeneration. In this regard, a biopsy of the affected areas of the mucosa with subsequent histological and cytological examination of the obtained material is of great diagnostic importance. If cellular atypia is detected during the study, removal of the affected area with leukoplakia is indicated.
Leukoplakia is a dyskeratosis, that is, keratinization disorders. It develops more often in middle-aged and elderly people. So leukoplakia of the cervix is most common in women aged 40 years. It occupies 6% of all cervical diseases. Laryngeal form accounts for a third of all precancerous conditions of the larynx. According to various observations, the transformation of leukoplakia into cancer occurs in 3-20% of cases. However, there are cases of simple leukoplakia, which is not accompanied by atypia of cells and are not precancerous conditions, but relate to the background processes of the body.
The causes and mechanism of leukoplakia have not been fully clarified. An important role in the development of the disease is assigned to the influence of external provoking factors: mechanical, chemical, thermal, etc. irritation of the mucous membranes. For example, according to the observation of gynecologists, a third of women with cervical leukoplakia have a history of data on diathermocoagulation. This is also confirmed by cases of leukoplakia associated with occupational hazards (exposure to the mucous membranes of coal tar, pitch, etc.).
Especially dangerous is the combined effect of several factors on the mucosa at once. Thus, the occurrence of leukoplakia of the oral mucosa is often caused by galvanic current formed from dissimilar metal prostheses and mechanical traumatization of the mucosa by these prostheses. Smokers usually have leukoplakia of the red border of the lips. It is caused by the effect of tobacco smoke and thermal factors on the mucous membrane (especially regular cauterization of the lip, which occurs when a cigarette is completely smoked), as well as chronic injury to the mucous membrane with a cigarette or a tube mouthpiece.
The cause of leukoplakia may be chronic inflammatory and neurodystrophic changes in the mucous membrane (for example, with stomatitis, gingivitis, vaginitis, chronic cystitis, etc.) Probably hereditary factors have a certain role in the development of leukoplakia, since its occurrence is observed in patients with congenital dyskeratosis.
Internal factors related to the state of the human body also play an important role in the development of leukoplakia. These are vitamin A deficiency, hormonal abnormalities, involutional restructuring of the genital mucosa, gastroenterological diseases that cause a decrease in the resistance of the mucous membranes to external irritating factors.
According to the peculiarities of morphological manifestations, the following forms are distinguished:
- verrucose (warty);
Each subsequent form of the disease develops against the background of the previous one and is one of the stages of the ongoing pathological process.
Most often, leukoplakia affects the mucous membrane of the oral cavity in the cheeks, corners of the mouth, lower lip, less often the lateral surface and the back of the tongue, the mucosa in the alveolar processes are involved in the process. Leukoplakia of the genitourinary organs can be located on the mucous membrane of the clitoris, vulva, vagina, cervix, glans penis, urethra and bladder. Leukoplakia of the respiratory tract is more often localized in the area of the vocal cords and on the epiglottis, rarely in the lower part of the larynx.
Leukoplakia is a single or multiple whitish or white-gray foci with clear contours. They can be of various shapes and sizes. As a rule, changes in the mucosa develop imperceptibly, without causing any negative sensations. In this regard, the disease is often an accidental diagnostic finding when visiting a dentist, performing colposcopy, circumcision of the foreskin (circumcision), etc. The exceptions are leukoplakia of the mucosa of the navicular fossa of the urethra, which leads to difficulty urinating, and leukoplakia of the larynx, which causes coughing, hoarseness of the voice and discomfort when talking.
The process of leukoplakia development consists of several stages passing one into another. It begins with the appearance of a small, mildly pronounced inflammation on the area of the mucous membrane. In the future, keratinization of the epithelium of the inflamed area occurs with the formation of a characteristic white focus of flat leukoplakia. Often the white color of the altered mucosa resembles a plaque or film. However, an attempt to remove the “plaque” with a spatula fails.
Over time, against the background of flat leukoplakia, verrucous develops. In this case, the lesion thickens and rises slightly above the surface of the mucosa. A whitish bumpy plaque with warty growths 2-3 mm high is formed . Against the background of keratinization foci, erosions and painful cracks may occur, characteristic of the erosive form of leukoplakia.
The main danger of leukoplakia is the possibility of its malignant transformation. The period of time after which malignant degeneration begins is very individual and depends on the form of the disease. Leukoplakia can exist for decades without turning into a malignant neoplasm. Verrucose and ulcerative forms are the most prone to cancer, and the highest percentage of malignancy is observed with leukoplakia of the tongue.
There are a number of signs by which it is possible to suspect a malignant transformation of one or another form of leukoplakia. Such signs include the sudden appearance of seals or erosions in the focus of flat leukoplakia, its uneven compaction, capturing only one edge of the focus. For the erosive form, the signs of malignancy are: the appearance of seals in the center of erosion, ulceration of the surface, the formation of papillary growths, a sharp increase in the size of erosion. It should be noted that the absence of these signs is not a guarantee of the goodness of the process and can be observed in the early stages of malignant degeneration of leukoplakia.
When leukoplakia is localized in places accessible to examination (oral cavity, glans penis, clitoris), the diagnosis usually does not cause difficulties. The final diagnosis is established on the basis of cytology and histological examination of the material obtained during a biopsy of the area of the altered mucosa.
Cytological examination is mandatory in the diagnosis of leukoplakia. It makes it possible to identify the cellular atypia characteristic of precancerous diseases. During cytological examination of smears from the affected area of the mucosa, a large number of cells of the multilayer epithelium with signs of keratinization are detected. However, cells from the lower layers of the mucosa, where atypical cells may be located, usually do not get into the smear. Therefore, with leukoplakia, it is important to conduct a cytological examination not of a smear, but of a biopsy material.
The histology of the biopsy material reveals a keratinizing epithelium that does not have a surface functional layer, since the upper layers of the epithelium are in a state of parakeratosis or hyperkeratosis. Various degrees of atypia of basal cells and basal cell hyperactivity can be detected, indicating the possibility of malignant transformation of the formation. Severe atypia is an indication for consultation with an oncologist.
Cervical leukoplakia is diagnosed by a gynecologist when examined in mirrors and during colposcopy. Conducting the Schiller test reveals areas of the mucosa that are not susceptible to iodine staining. If leukoplakia of the cervix is suspected, not only a biopsy of suspicious areas is performed, but also a curettage of the cervical canal. The purpose of this study is to exclude precancerous and cancerous changes in the endocervix.
If laryngoscopy is suspected of leukoplakia of the larynx, laryngoscopy is performed, revealing areas of white plaque tightly soldered to the underlying tissues. The study is supplemented with a biopsy. Diagnosis of leukoplakia of the urethra or bladder is carried out using urethro- and cystoscopy with a biopsy of the affected area.
It is necessary to differentiate leukoplakia from candidal mucosal lesions, lichen planus, manifestations of secondary syphilis, Bowen’s disease, keratinizing squamous cell skin cancer, Keir’s disease.
Leukoplakia of any form and localization requires complex treatment. It consists in eliminating the factors that provoked the development of leukoplakia, and concomitant disorders. This includes: the release of the oral cavity from metal prostheses, smoking cessation, elimination of hypovitaminosis A, therapy of gastrointestinal pathology, treatment of endocrine and somatic diseases, as well as infectious and inflammatory processes.
Simple leukoplakia without cellular atypia often does not require radical therapeutic measures. But such patients should be monitored and periodically examined. The detection of basal cell hyperactivity and cellular atypia during histological examination is an indication for the removal of the focus of leukoplakia in the near future.
Removal of the affected areas of the mucosa can be carried out using a laser or a radio wave method, by diathermocoagulation and electroexection (excision with an electric knife). It is undesirable to use cryodestruction, because after exposure to liquid nitrogen, rough scars remain on the mucosa. In some cases, surgical excision is required not only of the mucous membrane, but also of the affected organ (urethra, vagina, bladder), which entails reconstructive plastic surgery. Signs of malignant transformation of leukoplakia are an indication for radical operations followed by X-ray therapy.
Localization of leukoplakia on the laryngeal mucosa requires microlaryngosurgical surgery. Coagulation of the affected areas of the bladder mucosa is possible during cystoscopy. In the treatment of bladder leukoplakia, the introduction of ozonated oil or liquid into the bladder, as well as gaseous ozone, is successfully used. However, in the case of a persistent course of the disease, resection of the bladder is required.
Timely and adequate treatment of leukoplakia gives a positive result. However, it is impossible to exclude the occurrence of relapses of the disease. Therefore, in the future, the patient needs to be monitored. Folk methods of treatment and thermal procedures should be treated with caution. They can contribute to the malignant transformation of leukoplakia and worsen the course of the disease.