The common clinical allergic dermatoses include zoonoses, contact dermatitis, eczema, drug rash, atopic dermatitis, auto-sensitivity dermatitis, and papular zoonoses. The etiology and pathogenesis, clinical features and treatment of these diseases are described below:
Etiology and pathogenesis.
Contact dermatitis is an acute, subacute or chronic inflammatory skin disease that occurs at the skin and mucous membrane contact sites due to exposure to a substance, and is divided into two types: primary irritation and delayed metaplasia. The causative factors can be divided into two major categories: animal, plant and chemical. Such as animal fur, caterpillars, cryptomeria toxins, lacquer tree, pyrethrum, metal products, chemical materials, certain topical drugs, cosmetics, pesticides, rubber, plastics, etc..
If the exposure is allergenic in nature, the disease usually develops after 4 days of initial exposure and within 48 hours if re-exposed. If it is a primary irritant. The onset of the disease is usually within a few minutes to a few hours. It is called “lacquer sore” in Chinese medicine.
Clinical features: 1.
1. Medical history.
The length of the incubation period depends on the strength of the irritant. If the irritant is induced by a metabolic reaction, the initial onset is 4 to 20 days, and if the irritant has been sensitized, the onset is often within 24 hours after re-exposure to the allergen.
2.Clinical manifestations.
The rash mostly first appears at the site of direct contact, but can also spread to other parts. Generally, the hands, forearms, face, neck and other exposed areas; damage performance depends on the degree of reaction, from erythema, papules, herpes, blisters to ulcers, necrosis. The damage is more consistent and the margins are clearer. When the disease is prolonged, there may be infiltration thickening, local itching or burning sensation is often associated with heavy cases can be accompanied by hypothermia and other systemic reactions.
3, stop contact with suspected pathogenic substances, the rash often heal quickly.
4. Positive skin patch test: the suspected allergen or its single component is diluted with appropriate solvent to make appropriate concentration for this test, if positive, it means that the patient is allergic to the tested substance. This test has some diagnostic value for allergic contact dermatitis.
Treatment
1.Treatment principles.
Remove the cause of the disease, remove contact irritants and other external irritants, local cleaning treatment, according to the condition of the selection of appropriate topical and internal medication.
2.Western medicine treatment.
(1) systemic treatment: often use antihistamines, such as the first generation of ketamine, Antares, Benadryl and the second generation of cetirizine, loratadine, imipramine, terfenadine, etc.; when the lesions are heavy, consider short-term use of glucocorticoid steroids, such as prednisone 20-40mg in divided oral doses; or in the acute phase of severe disease with hydrogen succinate 200-300mg added to 5% glucose solution 500~1000ml of glucose solution, once a day, and gradually reduce the dosage and change to oral intake after the disease is controlled until the drug is stopped.
(2) Local selection of different topical agents according to different conditions: erythema, papules and blisters are not broken, no exudation, the use of furnace glycolate lotion; erythema, vesicles, exudate lesions with 3% boric acid solution wet dressing; papules, crust lesions with zinc oxide paste or glucocorticoid cream; mossy, chapped lesions with glucocorticoid ointment or 10%-20% urea ointment, feasible sealing package.
(3) Local or systemic antibiotics for secondary infections.
(4) occur in the eyelids, perioral and external genital areas of the lesions, should avoid the use of irritating or highly concentrated agents, available 2% Benadryl cream or 1% hydrocortisone cream.
3, Chinese medicine treatment.
Chinese medicine believes that the disease is externally affected by the poison of pungent heat or contact with a substance, because the endowment is not resistant, the skin and hair couples are not dense, the poison and heat contained in the skin and the onset. Chinese medicine identification of the disease.
(1) External attack of poisonous evil, skin contains heat; treatment should be to clear heat, cool blood, detoxify; formula with the addition and subtraction of clearing heat and removing dampness soup.
(2) Internal use of Chinese herbal medicine such as flower snake itch relief capsule.
(3) Topical application of compound No. 1 lotion, red sea stone lotion, etc.