Eczema is an inflammatory skin disease caused by a variety of internal and external factors with a pronounced tendency to exude, accompanied by significant itching, prone to recurrence, and seriously affecting the quality of life of patients. It is a common disease in dermatology, with a prevalence of about 7.5% in the general population in China. The United States is 10.7%. I. Etiology and pathogenesis The etiology of eczema is still unclear. Endogenous causes include abnormal immune function (such as immune imbalance, immunodeficiency, etc.) and systemic diseases (such as endocrine diseases, nutritional disorders, chronic infections, tumors, etc.) and hereditary or acquired skin barrier dysfunction. External factors such as, allergens in the environment or food, irritants, microorganisms, changes in ambient temperature or humidity, and sun exposure can trigger or aggravate eczema. Psychosocial factors such as stress and anxiety can also trigger or aggravate the disease. The pathogenesis of this disease is not clear. At present, it is mostly believed to be the result of a combination of internal and external factors based on internal factors such as abnormal immune function and skin barrier dysfunction. Both immune mechanisms such as allergic reactions and non-immune mechanisms such as skin irritation are involved in the pathogenesis. Microorganisms can trigger or aggravate eczema through direct invasion, superantigen action or induced immune response. The clinical manifestations of eczema can be divided into three phases: acute, subacute and chronic. The acute phase is characterized by erythema, edema on the basis of corn-grain papules, papules, blisters, vesicles and exudate, the center of the lesion is often heavier, and gradually to the surrounding compound extension. The periphery has scattered papules and herpes, so the boundary is unclear. In the subacute stage, the redness and exudation are reduced, and the vesicular surface is crusted and desquamated. Chronic eczema is characterized by coarse hypertrophy and mossy changes. It can be accompanied by pigmentation changes, and eczema on the hands and feet can be accompanied by nail changes. The rash is usually symmetrically distributed, often recurrent, and the conscious symptoms are pruritus, or even severe itching. Laboratory tests are mainly used for differential diagnosis and screening of possible causes, routine blood tests may include eosinophilia, increased serum eosinophilic cationic protein, increased serum IgE in some patients, allergen tests help to find possible allergens, patch test helps to diagnose contact dermatitis, fungal tests can identify superficial fungal disease, scabies tests can help to exclude scabies, serum immune Globulin testing can help identify congenital diseases with eczematous dermatitis lesions. Bacterial culture of skin lesions can help diagnose secondary bacterial infections, etc., and skin histopathology should be performed when necessary. Diagnosis and differential diagnosis The diagnosis of eczema is based mainly on clinical manifestations. Combined with the necessary laboratory tests or histopathological examination. Special types of eczema are diagnosed according to clinical features, such as dry eczema, self-sensitivity dermatitis, coin-shaped eczema, etc.; non-specific cases can be diagnosed according to clinical sites, such as hand eczema, calf eczema, perianal eczema, breast eczema, scrotal eczema, ear eczema, eyelid eczema, etc.; generalized eczema refers to eczema that occurs simultaneously in multiple sites. The severity of eczema can be scored according to its size and the characteristics of the rash. It needs to be differentiated from the following diseases: ①. It should be differentiated from other types of dermatitis with specific etiology and clinical manifestations, such as atopic dermatitis, contact dermatitis, seborrheic dermatitis, bruising dermatitis, and neurodermatitis; ②. It should be differentiated from diseases with similar eczema manifestations, such as superficial fungal disease, scabies, polymorphic heliotrope, eosinophilia syndrome, pellagra, and cutaneous lymphoma; ③. It should be differentiated from rare diseases with eczema-like skin lesions, such as Wiskott-Aldrich syndrome, selective IgA deficiency, and high IgE recurrent infection syndrome. V. Treatment The main goal is to control symptoms, reduce recurrence, and improve the quality of life of patients. Treatment should be considered as a whole, taking into account both the immediate and long-term efficacy, with special attention to medical safety in treatment. 1, basic treatment: ①, patient education: the need to explain the nature of the disease, possible regression, the impact of the disease on the health of the body, the presence of infectious, the clinical efficacy of various treatment methods and possible adverse reactions, etc., to guide patients to find and avoid common allergens and irritants in the environment, avoid scratching and excessive cleaning, the environment, diet, the use of protective equipment, skin cleaning methods, etc. should also be proposed accordingly. ②, avoid triggering or aggravating factors: through detailed history taking, meticulous physical examination, reasonable use of diagnostic tests, careful search for various suspected causes and triggering or aggravating factors, in order to achieve the purpose of removing the cause, treatment, such as dry eczema should be treated to make the skin dry factors. Infectious eczema should be treated for primary infection, etc.; ③, protection of the skin barrier function: eczema patients have damage to the skin barrier function, easy to secondary irritant dermatitis, infection and allergy and aggravate the lesions, so it is very important to protect the barrier function. The patient’s skin should be selected for treatment without irritation, prevention and timely treatment of secondary infections, subacute and chronic eczema with moisturizers for dry skin. 2, local treatment: is the main means of eczema treatment. According to the stage of the lesions should be selected according to the appropriate drug formulations. In the acute stage without blisters, vesicles, exudate, it is recommended to use furnace glycolate lotion, glucocorticoid cream or gel; a large number of exudate should choose cold wet compresses, such as 3% boric acid solution, 0.1% berberine hydrochloride solution, 0.1% ezacrine solution; vesicles but not much exudate can be used when the zinc oxide oil. In the subacute stage, topical zinc oxide paste and glucocorticoid cream are recommended for skin lesions. In the chronic stage, topical glucocorticoid ointment, hard cream, emulsion or tincture are recommended, and moisturizing agents and keratolytic agents, such as 20%-40% urea ointment and 5%-10% salicylic acid ointment, can be used in combination. (1), topical glucocorticoid preparations are still the main drugs used to treat eczema. Initial treatment should be based on the nature of the lesions to choose the appropriate strength of glucocorticoids: mild eczema is recommended to choose weak glucocorticoids such as hydrocortisone, dexamethasone cream; severe hypertrophic lesions are recommended to choose strong glucocorticoids such as harcinexide, halomethasone cream; moderate eczema is recommended to choose medium-acting hormones. such as tretinoin, mometasone furoate, etc. Weak or medium-acting glucocorticoids are generally effective in pediatric patients, facial and skin fold lesions. The continuous application of strong glucocorticoids generally does not exceed 2 weeks to reduce acute tolerance and adverse reactions. (2) Calcium-regulated neurophosphatase inhibitors such as tacrolimus ointment and pimecrolimus cream have therapeutic effects on eczema without the side effects of glucocorticoids, and are especially suitable for the treatment of eczema on the head, face and inter-rub areas. (3), bacterial colonization and infection can often induce or aggravate eczema [8], so antibacterial drugs are also an important aspect of topical treatment. Topical preparations of various antibacterial drugs are available, as well as combinations of glucocorticoids and antibacterial drugs. (4), Other topical drugs such as tar, antipruritic agents, and topical preparations of non-steroidal anti-inflammatory drugs can be selected for application according to the situation. 3, systemic treatment ①, antihistamines: choose appropriate antihistamines to stop itching and anti-inflammation according to the patient’s condition; ②, antibiotics: for those with extensive infection, it is recommended to systematically apply antibiotics for 7-10d; ③, vitamin C + calcium gluconate, etc. have certain anti-allergic effect and can be used for acute attacks or obvious itching; ④, glucocorticoids: generally do not advocate routine use. However, they can be used for patients with clear etiology and short-term elimination of etiology, such as those caused by contact factors, drug factors or self-sensitivity dermatitis; for severe edema, generalized rash, erythroderma, etc., they can also be applied short-term for rapid symptom control, but caution must be exercised to avoid systemic adverse reactions and rebound; ⑤. Immunosuppressants: they should be used with caution and the indications should be strictly controlled. It should be used only in patients with severe disease who have contraindications to the application of glucocorticosteroids, or after the short-term systemic application of glucocorticosteroids has been significantly relieved, and when the use of glucocorticosteroids needs to be reduced or stopped. 4, physical therapy: ultraviolet therapy, including UVA1 (340-400nm) irradiation, UVA/UVB irradiation and narrow-spectrum UVB (310-315nm) irradiation, has a better effect on chronic intractable eczema. 5, Chinese medicine therapy: Chinese medicine can be internal treatment or external treatment, should be based on the condition of evidence-based treatment. Chinese medicine extracts such as compound glycyrrhetinic acid glycosides, tretinoin polysaccharide, etc. are effective for some patients. It should be noted that herbal medicine can also lead to serious adverse reactions, such as allergic reactions, liver and kidney damage, etc. 6, follow-up and follow prevention: the disease is prone to recurrence, it is recommended that patients have regular follow-up. Acute eczema patients should preferably be seen 1 week after treatment, subacute patients 1 to 2 weeks after treatment, and chronic patients 2 to 4 weeks after treatment. The follow-up visit is to evaluate the efficacy, changes in condition, the need for further tests, and to evaluate compliance. For recurrent and persistent cases, attention should be paid to analyze the causes. The common causes are: ①. Irritating factors: Due to the destruction of the skin barrier function, new or weak irritants, or even substances that are not irritating under normal circumstances, also become irritants. Note that therapeutic medication can also produce irritation; ②, neglect of contact allergens: neglect of certain contact allergens in the family, occupation and hobby; ③, cross-allergy: pay attention to the cross-allergens that carefully check the allergens; ④, secondary allergy: pay attention to avoid secondary allergy to drugs (especially adrenal glucocorticoids) and chemicals (such as rubber latex in gloves); ⑤, secondary infection: skin barrier The destruction of skin barrier function, and the application of adrenal glucocorticoids, etc., can easily cause secondary bacterial or fungal infections; ⑥, unfavorable factors: sunlight, hot environment, continuous sweating, cold and dry can aggravate the condition; ⑦, systemic factors: such as diabetic patients prone to itching, secondary skin infections, etc.