Allergic contact dermatitis is an inflammatory skin disease that occurs in the place of its direct contact with an allergen. Allergic contact dermatitis is characterized by swelling and redness of the tissues that have come into contact with the allergen, itching, the appearance of papules and bubbles. Diagnosis is based on anamnesis and clinical data, the results of allergy tests and laboratory tests. In the treatment, the main role belongs to the elimination of contact with the substance or object that caused the occurrence of dermatitis. To eliminate swelling and itching, it is possible to use corticosteroid ointments, modern antihistamines.
L23 Allergic contact dermatitis
Allergic contact dermatitis is a common allergodermatosis that affects 1-2% of the population. The disease is more often registered in residents of industrialized countries who are active consumers of household chemicals, medicines, cosmetics, chemicals, etc. Unlike ordinary contact dermatitis, allergic dermatitis develops in sensitized individuals, i.e. in individuals with an allergic mood of the body. The majority of patients in clinical dermatology and allergology-immunology are young and middle-aged people.
Modern industry produces a huge number of chemicals that can cause allergic contact dermatitis. These are paints and varnishes, washing powders and other household chemicals, some components of perfumes and cosmetics, synthetic materials from which clothes are made and dyes with which they are painted. Chemicals with which a person is constantly in contact at work lead to the development of occupational dermatitis. Allergic contact dermatitis can be caused by certain medications. Plants such as hogweed, primrose, white ash, and others can also cause allergic contact dermatitis, which refers to phytodermatitis.
The allergen affects the skin, but the resulting allergic changes affect the entire body. The time during which sensitization develops and an allergic reaction occurs depends on how strong the allergen has affected the skin. An important role in this process is played by the state of the body itself: predisposition to allergic reactions, immune disorders in chronic inflammatory processes, thinning of the stratum corneum of the skin, etc. For example, with increased sweating, allergic contact dermatitis is more often observed, provoked by clothing made of dyed fabrics.
Inflammation develops according to a delayed type of allergic reaction, that is, with regular and sufficiently prolonged contact with an allergen substance. During this contact, the body is sensitized and hypersensitivity to the allergen develops. Local exposure to the skin triggers a tuberculin-like hypersensitivity reaction of the cellular type. When the allergen binds to tissue proteins, antigens are formed that cause activation of Langerhans cells and T-lymphocytes. The latter, in turn, begin to synthesize interleukins 1 and 2, gamma interferon, which stimulate the immune response and inflammatory response. Upon repeated encounter with the allergen, T-lymphocytes (memory cells) are rapidly activated, causing the development of allergic manifestations. Usually, from the moment of first contact with the allergen substance to the onset of symptoms, it takes from 7 to 10-14 days.
Skin changes in acute allergic contact dermatitis are always localized at the site of skin contact with the allergen and slightly go beyond this contact. Characteristic is the presence of clear boundaries of the lesion. Initially, redness of the skin and swelling of tissues develops. Then papules appear, filling with liquid quite quickly and passing into the stage of bubbles. After opening the latter, erosions form on the skin. When healing, they become covered with crusts. These changes on the skin are accompanied by severe itching. The process ends with peeling.
With continued exposure to the allergen against the background of an allergic reaction that has already occurred, a chronic form of allergic contact dermatitis develops. It is characterized by blurred boundaries of lesions on the skin and the spread of inflammatory changes to areas of the skin that are not in contact with the allergen. With a strong sensitization of the body, the generalization of the process is observed. Cutaneous manifestations of chronic allergic contact dermatitis are characterized by the formation of papules, dryness and peeling, thickening of the skin with increased skin pattern (lichenization). Constant itching leads to the appearance of secondary damage to the skin due to its constant combing (excoriation).
Allergic contact dermatitis is quite easily diagnosed by the symptoms characteristic of it and the identification of a connection with exposure to the skin of a substance that is a potential allergen. Skin tests help to accurately determine the cause of dermatitis. They are carried out by practicing allergists using special test strips with allergens applied to them. The strips are glued to the previously cleansed skin. An allergic reaction is determined by the appearance of redness and swelling at the place where the strip is pasted.
To identify concomitant diseases and differential diagnosis of allergic contact dermatitis, additional examinations are carried out: clinical and biochemical analysis of blood and urine, blood test for sugar, feces for dysbiosis. If necessary, an examination of the gastrointestinal tract and a study of the function of the thyroid gland are performed.
The main condition for the successful treatment of contact dermatitis is the complete elimination of the allergen that caused it. So if you are allergic to household chemicals, you should use protective gloves. If you are allergic to synthetic materials, you should wear only cotton underwear, and when buying clothes, carefully study the composition of the fabric. If you are allergic to metal, metal parts of clothing (zippers, buttons, hooks and buttons) should not come into contact with the skin, scissors and other tools should have plastic or wooden handles, it is also necessary to exclude the wearing of metal jewelry.
In the treatment of acute allergic contact dermatitis, the use of corticosteroid ointments is effective. When large bubbles form, they are punctured. To relieve itching and swelling, modern antihistamines are prescribed: cetirizine, loratadine, desloratadine, etc. In severe cases, corticosteroids are taken orally.
Prognosis and prevention
If the patient’s contact with the allergen is excluded, a complete recovery occurs. However, repeated contacts with the allergen are not always avoided, especially if it is a question of professional activity. In such cases, allergic contact dermatitis continues to develop, the sensitization of the body increases, the process is generalized and clinical manifestations take over the entire body. Prevention involves the exclusion of contact with causal allergens, and if contact is unavoidable, preventive intake of antihistamines.