Contact dermatitis is an inflammatory reaction of the mucous membrane of the skin due to contact with external substances, such as chemical clothing, cosmetics, drugs, etc. It is characterized clinically by edematous erythema at the site of contact. It is characterized clinically by the occurrence of sharp-edged damage at the site of contact, ranging from edematous erythema in mild cases to papules, bumps and even large scars in more severe cases, and epidermal loosening and even necrosis in more severe cases. If the cause can be removed early and treated appropriately, it can heal quickly, otherwise it may turn into eczema-like dermatitis.
There are many substances that can cause contact dermatitis. Some substances are allergenic at low concentrations and irritating and toxic at high concentrations. According to their nature can be divided into 3 categories.
1, animal: animal toxins, insect secretions, toxic hair, etc.
2, plant-based: pollen, plant leaves, stems, flowers and fruits, etc.
3, chemical: is the main cause of contact dermatitis. There are mainly metals and their products, plastics, rubber, spices, etc.
The onset of the disease is rapid, in contact with the site of the occurrence of clear boundaries of edematous erythema, papules, blisters of varying sizes; blister wall tension, the initial clarification of the liquid in the blister, the formation of pustules after infection; blister rupture to form a vesicular surface, and even tissue necrosis. If the contact material is gas, dust, lesions mostly occur in exposed parts of the body, such as the back of the hands, face, neck, etc., dermatitis boundaries are unclear.
Sometimes the contact is brought to other parts of the body, such as the vulva, waist, etc., due to scratching, similar dermatitis can occur. If the body is in a highly sensitive state, the lesions are not only limited to the contact area, but can be very extensive and even spread throughout the body. Self-perceived symptoms may range from itching to burning or swelling in severe cases. Systemic reactions include fever, chills, headache, nausea and vomiting. The course of the disease is limited. Removal of the cause can be cured after 1-2 weeks of appropriate treatment, but if re-exposed to the allergen can be re-emerged, repeated exposure, and repeated attacks. If not treated properly can develop into subacute or chronic inflammation, localized tinea-like lesions.
Symptoms of contact dermatitis
The contact site occurs clearly bounded edematous erythema, papules, blisters of various sizes; the wall of the blister is tense, the initial liquid in the blister is clarified, the infection forms a pustule; the blister ruptures to form a vesicular surface, and even tissue necrosis. If the contact material is gas, dust, lesions mostly occur in exposed parts of the body, such as the back of the hands, face, neck, etc., dermatitis boundaries are unclear. Sometimes the contact is brought to other parts of the body, such as the vulva, waist, etc., due to scratching, similar dermatitis can occur. If the body is in a highly sensitive state, the lesions are not only limited to the contact area, but can be very wide and even generalized.
Generally speaking, contact dermatitis can be divided into irritant contact dermatitis and allergic contact dermatitis.
The clinical manifestations of irritant contact dermatitis are: erythema, papules, edema, and edema, with erosion, oozing, and crusting after rupture. The local skin is pruritic, burning or painful, and the severity of symptoms is related to the concentration of exposure and the duration of exposure.
The symptoms of allergic contact dermatitis are different, manifesting as a period of latency, that is, not as soon as the contact begins. The diagnosis is confirmed by the patch test.
There is another type of contact urticaria. It appears immediately after contact with a substance and is characterized by a wind cluster, redness, itching, erythema, and edema. It usually disappears after a few hours. Common allergens include local anesthetics, insect stings, certain chemicals, etc.
Diagnosis
1. History of exposure to irritants or allergens.
2. The rash often occurs at the site of contact with the irritant.
3, the rash form often varies depending on the nature of the contact, such as allergens are often clear edges, erythema, papules, blisters, can also occur self allergy; such as irritants are often red, swollen, blisters or blisters, erosion and even necrosis can occur.
4, there is itching and burning sensation, heavy with pain, fever and other systemic symptoms.
5, the course of the disease is self-limiting, certain allergens caused by the rash can be removed after the cause of l to 2 weeks can subside.
6. Positive skin patch test for allergens.
Modern medical treatment of the disease is to stop contact with the allergen, immediately rinse the contact area with water, apply soothing anti-inflammatory and anti-itch topical and internal anti-allergy drugs. If necessary, add corticosteroids and choose antibacterial and internal medicine.