Bowen’s disease is an intraepidermal cancer of the skin and mucous membranes, a type of carcinoma that affects the scaly cells of the epidermis, but does not spread to basal cells. Pathological foci have the appearance of plaques of rich pink or red color with raised, uneven, clearly delimited edges. The surface of the plaques is covered with horny scales, brown and grayish crusts. The diagnosis is made on the basis of anamnesis, general examination, dermatoscopy, histological examination of tissue samples. Treatment is mainly surgical: complete removal of the affected areas prevents the development of invasive skin cancer.
D04 Carcinoma in situ of the skin
Synonymous names of the pathological process: Bowen’s dyskeratosis, discoid lentil-shaped dyskeratosis. The first to give a detailed clinical description of the disease was the American dermatologist John T. Bowen at the beginning of the XX century. The disease is rarely diagnosed in children and young people. The incidence of discoid dyskeratosis increases in patients older than 65 years. Men get sick more often than women. People living in regions with intense solar insolation are more likely to get sick. According to statistics, 15 new cases of pathology per 100 thousand white population are registered annually in the USA. In the Hawaiian Islands, this figure is almost 10 times higher.
The occurrence of characteristic changes in Bowen’s disease is a consequence of prolonged, often chronic exposure to open areas of the skin and mucous membranes of damaging environmental factors. Less often there is a connection with endogenous causes (viral infection, neoplasia). The main factors include:
- Exposure to ultraviolet radiation. The probability of the appearance of dyskeratosis is directly dependent on the growing total doses of solar exposure that have occurred in the past of sunburn. The type of ultraviolet radiation does not matter significantly. With the same probability, damage to the skin can be caused by the sun’s rays and the light of the solarium lamps.
- Exposure to carcinogenic substances. Inflammation, atrophy, hyperplasia and other cell changes in the contact areas of the skin can be triggered by coal tar, mineral oils, arsenic, crude kerosene and a number of other substances. One-time contact with carcinogens does not cause tissue degeneration. The cumulative effect matters. These may be occupational hazards or local treatment with drugs containing arsenic, chloromethine and other aggressive compounds.
- Human papillomavirus. HPV viruses of nine different subtypes were isolated from patients with Bowen’s disease. The greatest importance in the genesis of the disease, according to researchers, belongs to the 16th subtype. A feature of viruses is the ability to integrate into the genome of cells and cause changes in their properties, in particular, the ability to divide.
- Paraneoplastic processes. A number of researchers suggest that the appearance of lentil-like dyskeratosis is associated with oncological diseases of internal organs in 15-70% of cases, especially if the foci are localized in places that are hidden by clothing. Studies conducted in different countries give contradictory results on this issue, but this possibility cannot be excluded.
Among the predisposing factors for the development of Bowen’s dyskeratosis can be attributed immunosuppression, which is associated with a decrease in immune control over the appearance of atypical cells in tissues. The body is weakened by severe endocrine and somatic diseases, injuries and surgical interventions. It is suggested that chronic mechanical damage to the skin plays a role in the development of characteristic local symptoms. Of great importance in the structure of morbidity is the belonging of a person to 1 or 2 phototype of the skin, when the skin quickly burns in the sun.
The development of the disease is associated with a change in the mitotic activity of the cells of the growth layer of the epidermis due to a mutation of the main tumor suppressor gene TP53. At the site of the development of the pathological process, the skin thickens due to a rapid increase in the number of spiny cells. For a long time, tumor growth has been localized in the epidermis, but subsequent mutations contribute to the movement of cancer cells into underlying tissues, their spread by hematogenic and lymphogenic pathways.
An increase in the degree of malignancy of a neoplasm can occur gradually or abruptly under the influence of provoking external and internal factors. As long as the altered cells are located above the basement membrane (the boundary between the epidermis and the dermis), Bowen’s disease is regarded as a non-invasive cancer. As soon as the pathological growth covers the dermis, we can talk about invasive cancer.
Bowen’s disease symptoms
Characteristic external manifestations of pathology are single or multiple spots, plaques on the skin. A favorite localization of formations is open areas of the body: the head and neck in men, the lower limbs and cheeks in women. There are plaques on the trunk, genitals, upper extremities, on the oral mucosa. The diameter of the plaques varies widely and ranges from 2 mm to 5 cm. Skin formations grow slowly, gradually spreading to the surrounding tissues. Adjacent elements may merge over time.
The edges of the formations are uneven, slightly raised, the pink or red surface is abundantly flaked. The formation of dense crusts on the surface of the elements is often accompanied by the appearance of cracks. When the crusts are removed, the wet pink surface is exposed. As the disease progresses, areas of atrophy, warty growths, and foci of uneven thickening of the epidermis may appear on the surface of plaques.
On the genitals, plaques may contain pigment, and on the head of the penis, the surface of the formations may be velvety or, conversely, smooth. When the formation is located on the nail phalanx, peeling is observed around the nail, and the nail plate itself can deform and melt over time. The lesion of the skin folds is accompanied by the development of erythematous or chronic nonspecific dermatitis, the addition of an unpleasant odor. Ulceration of the surface of the rash elements, contact bleeding indicate the degeneration of foci of discoid dyskeratosis into invasive cancer.
Bowen’s disease is a so–called “background disease”, on the basis of which squamous cell skin cancer can form. The frequency of transition of lentil-like dyskeratosis to cancerous growth is 3% when the elements are located on the skin of the trunk and limbs and up to 10% when the genitals are affected. In this regard, most oncologists consider Bowen’s disease as an intraepidermal form of squamous cell carcinoma in situ and recommend removing the foci immediately.
It can be difficult for a dermatologist to make a diagnosis based on the appearance of plaques alone. To establish the nature of the pathological process, the stage of the disease, the presence of concomitant diseases in the patient that may affect the effectiveness of treatment, a comprehensive examination is carried out, which, in addition to general clinical and laboratory tests, includes:
- Epiluminescent microscopy. The use of an optical or electronic dermatoscope allows the doctor to obtain an image of intradermal structures that are indistinguishable to the naked eye. A characteristic feature of plaques with discoid dyskeratosis is the abundant interspersing of single vessels and vascular plexuses, which are located on a uniform pink or red background.
- Digital ultrasound imaging. Unlike conventional soft tissue ultrasound, the method involves the use of devices whose sensors operate at a frequency of 20-100 MHz. Thanks to this, with the help of high-resolution digital ultrasound imaging, it is possible to study the structure of the skin and its individual layers without tissue damage, and to save the results of studies in order to further compare them with each other.
- Confocal laser scanning microscopy. The method allows to obtain images of the layers of the epidermis and dermis, comparable in quality and information content with a conventional microscopic examination. The difference lies in the fact that with scanning microscopy, the analysis of the structure of tissues and individual cells is carried out without their preliminary removal from the body: the lens of the lens is fixed on a certain part of the body and transmits the received data to the memory of the device. There is no need for a biopsy.
- Morphological examination. This is the “gold standard” for the diagnosis of malignant skin neoplasms. Depending on the structure and distribution of the altered cells in the epidermis, dermis, subcutaneous tissue, the doctor can classify the disease, determine its stage, determine the prognosis for life and recovery. For the study, tissue samples are obtained by biopsy.
- Analysis of the antigenic structure of the tumor. The immunohistochemical diagnostic method involves the use of monoclonal antibodies in order to identify specific molecular markers on the surface and inside pathologically altered cells. Using antibodies to individual components of the cytoplasm and cell membrane, it is possible to determine the type of tumor, the degree of differentiation, and the ability to invade.
The differential diagnosis of Bowen’s disease is carried out with a number of oncological diseases: cancer of the sweat glands, basal cell carcinoma, an extramammary variant of Paget’s disease. Dermatological problems that resemble lentil-like dyskeratosis in their clinical manifestations include coin-shaped eczema, psoriasis, solar keratosis.
Therapeutic and operative methods of removing foci used in modern medicine have their advantages and disadvantages. However, the variety of approaches to therapy makes it possible for a dermatooncologist to choose the most appropriate method of treatment, taking into account the localization of the neoplasm, its size, the patient’s condition and the presence of concomitant pathology.
Local exposure to lesions can reduce the overall load on the body, which is especially important for weakened patients, patients with immunodeficiency, drug intolerance and other limiting factors. The methods of therapeutic treatment include:
- Local use of medicines. Creams with imiquimod or 5-fluorouracil are prescribed. The duration of treatment for each of the patients is determined individually, ranging from 1 week to 2-3 months. Provide deeper penetration of 5-fluorouracil, achieving a significant concentration of it in the tissues by occlusive dressings, ionophoresis or preliminary laser irradiation of the pathological focus.
- Photodynamic therapy. The method involves the use of means that increase the sensitivity of tissues to light exposure. The active ingredients of drugs accumulate mainly in the lesions. Under the influence of light, tumor cells die. Photodynamic treatment is indicated primarily for patients with multiple foci of a significant area.
The method of removal of altered tissues is determined by the technical equipment of the clinic, the level of training of the surgeon. High-tech methods allow for treatment with a lower risk of recurrence and scarring, but they are not available everywhere. Simpler methods do not require significant time and money in order to get a satisfactory result. Surgical treatment may include:
- Simple prompt removal. The surgeon excises the neoplasm within healthy tissues. A sample of skin with dyskeratosis is sent to the laboratory for express diagnostics. The edges of the wound are tightened or skin grafting is performed. The method is suitable for the elimination of pathological foci of a small area located on the trunk and limbs. Noticeable scars may remain on the face.
- The Mohs micrographic operation. This surgical technique allows you to remove the neoplasm layer by layer without damaging healthy tissues. It is used for relapses of Bowen’s disease, immunodeficiency conditions, to remove elements in high-risk areas: around the eyes and nose, in the genital area. More subtle and accurate work of the surgeon reduces the likelihood of scarring.
- Curettage. Scraping the lesion with a curette allows you to remove the epidermis with foci of intraepidermal cancer. The procedure has a small number of contraindications, is carried out under local anesthesia, does not violate the patient’s well-being, therefore its use is justified in a wide range of people of the older age group.
- Cryotherapy. The method is effective against single formations of small diameter. Under the influence of liquid nitrogen, the altered tissues are irreversibly damaged and after a while they dry out into a dense crust. The healing of foci occurs without scarring. Cryotherapy does not require prior anesthesia, except for the sensitive area of the face.
- Laser ablation. The procedure is performed on a neodymium or carbon dioxide medical laser system. By changing the settings of the device, the surgeon can control the depth and extent of tissue damage. With the help of a laser, single foci of small size are removed. Laser treatment is performed under local anesthesia. After removal of neoplasms located in the upper layers of the skin, the risk of scarring is minimal.
Prevention and prognosis
The prognosis for recovery is favorable. Bowen’s disease is not life-threatening. After conservative or surgical removal of plaques, relapses are possible, which respond well to treatment. The patient needs to visit his attending physician 1 time every 6-12 months for timely detection of the reappearance of plaques.
It is possible to reduce the likelihood of developing pathology by refusing to visit tanning salons, limiting exposure to the open sun in the warm season, using hats, caps with visors, shirts and dresses with long sleeves, care cosmetics with sun filters. It is recommended to change jobs in the presence of occupational hazards, preventing permanent injury to the skin with protective clothing and gloves.