Dermatitis

Dermatitis - inflammatory skin reaction in response to the effects of environmental stimuli. Distinguish contact dermatitis and toxicermy. Contact dermatitis occurs under the influence of direct external factors on the skin, with toxemia the latter initially penetrate into the internal environment of the body.

Etiology and pathogenesis. Irritants, which cause dermatitis, are of a physical, chemical or biological nature. The so-called obligate stimuli cause simple (artificial, artefactual) dermatitis in every person. These include friction, pressure, radiation and temperature effects (see Burns and Frostbites), acids and alkalis, some plants (nettle, ash, cauliflower, euphorbia, etc.). Optional stimuli cause skin inflammation only in persons with k (Sensitization) dermatitis.The number of facultative irritants (sensitizers) is enormous and continuously increasing.The most practical of them are the salts of chromium, nickel, cobalt, formalin, turpentine, polymers, medicines, washing powders, cosmetics, objects Perfumes, insecticides, some plants (primula, aloe, tobacco, snowdrop, geranium, garlic, etc.).

The pathogenesis of simple dermatitis is reduced to direct damage to skin tissue. Therefore, the clinical manifestations of simple dermatitis and its course are determined by the strength (concentration), the duration of the exposure and the nature of the stimulus, with skin damage occurring immediately or soon after the first contact with the stimulus, and the lesion area strictly corresponds to the area of ​​this contact.

At the heart of allergic dermatitis is monovalent skin sensitization. Sensitizers that cause allergic dermatitis are usually haptens. Combining with the skin proteins, they form conjugates that have the properties of full allergens, under the influence of which lymphocytes are stimulated, which causes the development of sensitization dermatitis as an allergic reaction of a delayed type. A huge role in the mechanism of sensitization is played by individual characteristics of the organism: the state of the non-congenital system (including vegetative), genetic predisposition; Transferred and concomitant diseases (including foot mycoses), the state of the water-lipid mantle of the skin, and also the functions of the sebaceous and sweat glands.

Monovalent sensitization determines the features of the clinic and the course of allergic dermatitis: clear specificity (dermatitis develops under the influence of a strictly defined stimulus); The presence of a latent (sensitization) period between the first contact with the stimulus and the onset of dermatitis (from 5 days to 4 weeks), an unusual intense inflammatory skin reaction, an inadequate concentration of the stimulus and the time of its exposure; The vastness of the lesion, which goes far beyond the area of ​​the stimulus.

Clinical picture. Simple dermatitis is acute or chronic. There are three stages of acute dermatitis: erythematous (hyperemia and puffiness of varying severity), vesicular or bullous (on the erythematous-edematic background, bubbles and blisters are formed that dry out into the crusts or open up with the formation of wet erosion), necrotic (tissue decomposition with ulceration and subsequent Scarring). Acute dermatitis is accompanied by itching, burning or pain, which depends on the extent of the lesion. Chronic dermatitis, caused by prolonged exposure to weak stimuli, is characterized by congestive hyperemia, infiltration, lichenification, cracks, increased cornification, and sometimes skin atrophy.

One of the most common varieties of acute dermatitis is abrasion, which usually occurs on the palms of the hands, especially the streets that do not have the habit of manual labor, and the feet when walking in uncomfortable shoes. Clinically characterized by sharply outlined edematous hyperemia, against the background of which, with the continuing impact of the irritating factor, large bubbles appear - "water blisters"; It is possible to join the pyococcal infection. Omozolelost - a chronic form of mechanical dermatitis - develops due to prolonged and systematic pressure and friction on the hands when performing manual operations (professional sign), and on the feet - when wearing tight shoes. Loss can also occur in the folds of friction of contacting surfaces, especially in obese persons.

Solar dermatitis, clinically taking place in the erythematous or vesicle-bulbous type, is characterized by the presence of a small (up to several hours) latent period, the vastness of the lesion and the outcome of pigmentation (sunburn); Common phenomena are possible. Similar changes can also give sources of artificial ultraviolet radiation. As a result of prolonged insolation, to which people subjected to long-term outdoor activities (geologists, shepherds, fishermen) are exposed, chronic dermatitis develops.

Radiation dermatitis proceeds in the same way irrespective of the type of ionizing radiation. Acute radiation dermatitis arising from a single irradiation, less often with radiation treatment (radio epidermis), may be erythematous, vesiculobullous or necrotic, depending on the radiation dose. The latent period has a prognostic value: the shorter it is, the heavier the dermatitis is. Ulcers differ torpid current (many months, even years) and painful pain. There are general phenomena with changes in blood composition. Chronic radiation dermatitis develops as a result of prolonged exposure to ionizing radiation in small but exceeding the maximum permissible doses: dry, atrophic skin is covered with scales, telangiectasias, depigmented and hyperpigmented spots, hyperkeratoses, trophic ulcers prone to malignancy.

Acute dermatitis, caused by acids and alkalis, proceeds according to the type of chemical burn: erythematous, vesiculobullous or necrotic. Their weak solutions with prolonged exposure cause chronic dermatitis in the form of infiltration and lichenification of varying degrees of severity.

The diagnosis of simple dermatitis is based on a clear connection with the effect of the stimulus, the rapid occurrence after contact with it, the sharp boundaries of the lesion, rapid involution after the elimination of the stimulus.

The clinical picture of allergic dermatitis is characterized by a clear erythema with a pronounced edema. Against this background, there may appear numerous bubbles and bubbles, which, when opened, cause erosive erosion. When the inflammation subsides, crusts and scales are formed, after which the cyanotic-pink spots remain for a while. Allergic tests are used to confirm the diagnosis.

Treatment. Elimination of the stimulus. In the erythematous stage - indifferent powder and water-agitated suspensions. Bubbles, especially with scuffs, should be opened and treated with aniline paints. In the vesiculobuluse stage - cold lotions (see Eczema). In all forms and stages, except for ulcers, corticosteroid ointments are indicated, with piococcal complications, with disinfectant components. In the case of chemical burns, first aid consists in immediate, profuse and prolonged washing with water. Treatment of ulcerative necrotic lesions is performed in a hospital.

Prevention. Compliance with occupational safety at work and at home; Timely sanation of focal infection and foot mycoses; The use of antibiotics and other sensitizing drugs is strictly according to the indications given their tolerability in the past.

The prognosis is usually favorable, with the exception of necrotic dermatitis of chemical and especially radiological etiology. See also Toxidermy.