Dermatitis

Dermatitis is an inflammation of the skin, often of allergic origin, caused by various agents: chemical, physical, etc.

Dermatitis is the most common skin pathology caused by constant exposure to various environmental factors both in everyday life and in conditions of large-scale industrial production and agriculture. In the general structure of dermatological pathology leading to temporary loss of working capacity, dermatitis accounts for 37 to 65%. varying in severity and reasons for their development.

New chemical compounds, synthetic materials, hydrocarbons, as well as various production factors lead to a worsening of the situation, contributing to a sharp increase in dermatitis diseases, especially of an allergic nature.

Dermatitis is an inflammatory reaction of the skin that occurs in response to exogenous irritants of physical, chemical and biological nature.

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Causes of dermatitis

Most dermatitis is based on manifestations of delayed-type hypersensitivity, i.e. foci of inflammation arise on an immune basis with the involvement of the microcirculatory bed and complex biomorphological, tissue and cellular processes developing in this area.

Factors affecting the skin from the outside are divided into physical, chemical and biological by their etiology. By the nature of their impact, they are divided into:

• unconditional (obligatory), capable of causing dermatitis with a certain strength and duration of exposure in each person (mechanical damage, high temperature and other physical factors, concentrated acids and alkalis).
• conditional (optional), causing dermatitis only in individuals with increased sensitivity to them (washing and cleaning agents, turpentine, nickel salts, formalin, chromium compounds, dinitrochlorobenzene, furacilin, rivanol, etc.)

Dermatitis that occurs under the influence of unconditional irritants is called simple, artificial, artificial dermatitis that occurs under the influence of conditional irritants-sensitizers is called allergic.

Depending on the course of the disease, dermatitis is divided into acute and chronic.

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Pathogenetic mechanisms of dermatitis

1. In the development of simple contact dermatitis, which occurs in response to the action of unconditional (obligate) irritants, the leading role is given to the strength and duration of the damaging factor. The consequence of this may be a significant area and depth of damage to the skin. Individual reactivity of the skin plays only an auxiliary role, contributing to a faster or slower restoration of the integrity of the skin or the attenuation of the inflammatory reaction (age-related characteristics of the body, individual ability of the skin to regenerate)
2. In the development of allergic dermatitis, which occurs as a result of contact of the skin with exoallergens (chemical sensitizers, polymers, synthetic resins, low-molecular substances of plant origin, drugs - antibiotics, sulfonamides, rivanol, furacilium, novocaine, etc.), sensitization of the skin occurs, that is, an increase in sensitivity to this allergen. In the process of sensitization, an immunological response is formed in the form of the formation of specific antibodies or sensitized lymphocytes. Langerhans cells (white dendritic epidermocytes) play a significant role in the formation of the primary immune response.

The state of the epidermal barrier, which is in complex dependence on the activity of the nervous, endocrine and immune systems, is of great importance in the development of the disease. Allergic dermatitis, which occurs as a manifestation of delayed-type hypersensitivity, occurs due to the ability of all types of contact allergens to combine with skin proteins.

The main stages of dermatitis development

Risk factors that contribute to the development of simple contact dermatitis, especially in industrial conditions, are non-compliance with safety regulations and violation of working conditions, which lead to damage to exposed areas of the skin. The degree of inflammatory reaction is directly dependent on the strength and duration of exposure to the damaging factor.

The development of allergic dermatitis is mainly facilitated by poorly conducted professional selection, which did not take into account the presence of allergic diseases in the past of persons employed in a particular industry or agriculture, and then - the peculiarities of working conditions (non-compliance with production technology) and everyday life (sensitization to household allergens). In addition, the presence of chronic diseases that change the reactivity of the body as a whole and the skin in particular also contributes to the development of allergic dermatitis.

Pathomorphology of dermatitis

In all clinical forms of dermatitis, the epidermis and dermis are involved in the process. The histological picture is rarely specific, which complicates diagnosis, but the predominance of one or another component of inflammation can serve as a starting point for determining the type of dermatitis. In acute dermatitis, due to severe disorders in the microcirculatory bed, accompanied by sharp disturbances in the permeability of the vessel walls, the exudative component comes to the fore. In the upper parts of the dermis, there is a sharp expansion of the capillaries, edema and mononuclear, mainly perivascular infiltrates. In the epidermis, due to severe edema, as a rule, blisters and vesicles, pronounced spongiosis, intracellular edema near the blisters are found. Increased edema leads to reticular dystrophy of the epidermis and an increase in the number of blisters. Merging, they form large, multi-chambered blisters that contain serous exudate with an admixture of mononuclear cells at the beginning and neutrophilic granulocytes at later stages of the disease. There may be crusts in the stratum corneum.

The histological picture of subacute dermatitis is characterized by spongiosis, intracellular edema and the presence of blisters in the epidermis, which are usually small in size and located in distinguishable sections of the epidermis between edematous cells. Subsequently, as a result of the proliferation of epidermocytes around the blisters, they seem to move into the upper layers of the epidermis, settling in the upper parts of the germinal layer. Acanthosis and parakeratosis are sometimes observed. The inflammatory infiltrate in the dermis is similar in composition to that in acute dermatitis, the edema and vascular reaction are somewhat reduced.

In chronic dermatitis, moderate acanthosis with elongation of epidermal outgrowths, hyperkeratosis with areas of parakeratosis, slight spongiosis, but without vesicles are observed. Inflammatory infiltrates are localized mainly perivascularly in the upper parts of the dermis, their cellular composition is the same as in subacute dermatitis; exocytosis is usually absent. The vessels are somewhat dilated, the number of capillaries is increased, proliferation of collagen fibers is noted in the upper parts of the dermis, including the papillae.

Symptoms of dermatitis

Simple contact dermatitis is characterized by the following symptoms:

1. The clarity of the boundaries of the lesion, more often in open areas, corresponding to the boundaries of the impact of the damaging factor.
2. An inflammatory response of the skin, corresponding to the strength and duration of the impact of the damaging factor and manifested by monomorphic rashes, in connection with which the stages of the process can be traced:
   • erythematous stage, characterized by inflammatory hyperemia and edema;
   • bullous-vesicular stage - the appearance of tense blisters, blisters filled with serous, less often serous-hemorrhagic contents;
   • ulcerative-necrotic stage - the formation of areas of necrosis with subsequent ulceration and scarring, leading to gross deformations of the skin.
3. After contact with the damaging factor ceases, inflammatory changes resolve depending on the depth of the lesion and the patient’s skin’s ability to regenerate (age, condition of the skin prior to the disease).

Allergic dermatitis occurs in sensitized patients and is characterized by the following symptoms.

1. Lack of clarity of the boundaries of the lesion, with possible spread to areas adjacent to the contact zone, especially with the involvement of nearby skin folds in the process;
2. Polymorphism of rashes (true and false), which does not allow to identify the stages associated with the strength of the effect of the allergen factor, but occurs with severity due to the degree of sensitization. Rashes are most often represented by areas of dull erythema, against the background of which papular, vesicular and vesicular elements are located. Droplet oozing may occur, with further drying of the serous exudate and the formation of small layered crusts, creating a picture of peeling.
3. After contact with the allergen has ceased, inflammatory phenomena on the skin may subside, but in rare cases they may increase, depending on the degree of sensitization. In the future, in the absence of qualified medical care, with an unspecified nature of the allergen, the acute course of the disease may become chronic, with further transformation into an eczematous process.

Depending on the course, dermatitis is divided into acute, subacute and chronic. The clinical picture is characterized by polymorphism of rashes. The range of manifestations can vary from limited edematous erythema to pronounced vesicular and even necrotic changes, generalized erythematous, erythematous-nodular, papulovesicular and vesicular rashes, accompanied by itching of varying degrees. Allergic dermatitis can often recur, which is why infiltrates develop in the lesions, which are often eczematoid in nature and serve as a basis for the development of eczema.

Differential diagnosis of dermatitis

Diagnosis of simple dermatitis is usually not difficult, but one should be aware of the possibility of self-harm to the skin (pathomimia) by people with unstable psyche.

Allergic dermatitis should be differentiated from eczema, which is characterized by a more persistent course, prevalence and polyvalent sensitization, pronounced evolutionary polymorphism (microvesicles, microerosions, microcrusts). In addition, one should remember about the development of professionally caused allergic dermatitis, which requires confirmation by an occupational pathologist.

Indications for hospitalization of the patient are the extent of skin lesions, pronounced subjective sensations (itching, pain), a clinical picture represented by vesicular-bullous elements, foci of necrosis.

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Treatment of dermatitis

In simple contact dermatitis, symptomatic treatment is indicated. At the erythema stage, lotions (1-2% solution of tannin, boric acid, 0.25% solution of silver nitrate) or short-term steroid ointments (celestoderm, prednidolone, sinaflan) are used; at the stage of vesiculation and blister formation, wet-drying dressings with the above solutions are used. Then, after opening the blisters, the erosive surfaces are treated with an aqueous solution of aniline dyes (1-2% solution of brilliant green, methylene blue, Castellani liquid) followed by lubrication of the skin with ointments of epithelializing action (5% methyluracil ointment, solcoserium cold cream).

In the necrosis stage, surgical excision or administration of leading enzymes (trypsin, chymotrypsin) in the form of lotions is indicated, followed by the use of epithelializing agents.

For the treatment of allergic dermatitis, patients in the early stages need to be prescribed desensitizing agents (antihistamines, calcium preparations) in combination with external treatment methods (5% dermatol emulsion, lanolin emulsion, zinc ointment, 3% naphthalene paste, cold cream).