Allergic contact dermatitis

Contact allergic dermatitis occurs in patients in response to the facultative stimulus (allergen), to which there is increased sensitivity. At the heart of allergic dermatitis is an allergic reaction of a delayed type. As an allergen often act as medicinal and chemical substances. They (haptens), when combined with epidermal proteins, acquire the properties of a complete antigen. Allergens bind to mast cells (macrophages) of the epidermis, which transmit information about the antigen to T-lymphocytes. In response to this, proliferation of T-lymphocytes occurs with the formation of a population of cells specific for this antigen. With repeated contact of the allergen, sensitized lymphocytes accumulate in the locus of exposure to the allergen. Lymphocytes secrete various interleukins that attract fat cells, polymorphonuclear leukocytes to the focus. As a result of the degranulation of the latter, biologically active substances (histamine, bradykinin, etc.) are released, which contribute to the formation of an acute inflammatory process in the skin.

[1], [2], [3], [4]

Histopathology

There are intercellular edema in the epidermis, hypertrophy and hyperplasia of the endothelium and perithelium of the vessels, narrowing of their lumen. Around the vessels there is perivascular infiltration, consisting of lymphoid cells, macrophages, fibroblasts with an admixture of basophils in various stages of degranulation.

Symptoms of contact allergic dermatitis

For allergic dermatitis, the true polymorphism of the rash is localized in the areas exposed to the allergen. In patients with erythema with fuzzy boundaries, papules and edema, clinical manifestations characteristic of eczema (vesiculation, wetness, propensity to relapse) are noted. But they are less pronounced with allergic contact dermatitis.

In some patients, clinical manifestations go beyond the zones of exposure to allergic agents. In varying degrees, subjective sensations are noted: itching, burning, feeling of heat in the lesions. There were cases in patients who experienced acute allergic contact dermatitis after applying 33% sulfuric ointment for scabies and treatment of the genital area with chlorhexidine solution.

Diagnosis and differential diagnosis

The disease should be distinguished from simple contact dermatitis and eczema.

[5], [6], [7], [8], [9], [10]

Treatment of contact allergic dermatitis

First, it is necessary to eliminate the cause that caused contact allergic dermatitis. In severe clinical manifestations prescribed antihistamine (tavegil, fenistil, analergin, diazolin, suprasti, etc.) and hyposensitizing agents (calcium chlorine or calcium gluconate, sodium thiosulfate), vitamins. In severe cases of patients hospitalized and recommended systemic glucocorticosteroids.

External therapy is performed taking into account the stage of the disease and the severity of the inflammatory process. With severe erythema, zinc oxide, white clay in the form of powders, aqueous stirring suspensions, zinc ointments (2-5%), creams and ointments containing glucocorticosteroids are prescribed. Of the analgesic local remedies, a good effect is provided by fenistil-gel. In the case of exudation, lotions are used, as well as aniline dyes, indifferent pastes. To dissolve the process used ointments that have a resolving effect (5-10% ichthyol, 2% sulfuric salicylic, 2% sulfur tar).