Dermatologic diseases are a general term for diseases that occur in the skin and the skin’s accessory organs. Skin is the largest organ of the human body, skin diseases are not only a variety of types, a variety of internal organs occurring in the disease can also be manifested in the skin. There are many causes of skin diseases, such as skin diseases caused by infectious factors, such as leprosy, scabies, fungal diseases, skin bacterial infections, etc. often have a certain degree of contagious, not only affecting health, but also cause panic and social discrimination, but with the improvement of people’s living standards and scientific and technological advances, leprosy and other infectious diseases around the world has been significantly controlled. Other internal and external factors that cause skin diseases, such as mechanical, physical, chemical, biological, endocrine, immune, etc., are now receiving more and more attention. Classification 1.Viral skin diseases Common herpes simplex, herpes zoster, warts (common warts, plantar warts, flat warts, molluscum contagiosum, condyloma acuminatum), chickenpox, rubella, hand, foot and mouth disease. 2. Bacterial skin diseases Commonly, there are impetigo, folliculitis, boils, carbuncles, cellulitis, dengue and leprosy. 3. Fungal skin diseases: Tinea capitis, ringworm, tinea cruris, nail fungal disease, macular furuncle, malassezia folliculitis. 4. Animal-induced skin diseases such as scabies, mite dermatitis, cryptococcal dermatitis, lice disease, insect chelating injuries or bites. 5. Sexually transmitted diseases such as syphilis, gonorrhea and condyloma acuminatum. 6. Allergic and autoimmune skin diseases Commonly contact dermatitis, eczema, urticaria; allergic skin vasculitis, drug dermatitis, anaphylaxis and so on. 7. Physical skin diseases Commonly, there are sunlight dermatosis, summer dermatitis, prickly heat, frostbite, corns, cracked hands and feet, pressure sores. 8. Neurological dysfunction of skin diseases Common pruritus, neurodermatitis and parasitic paranoia. 9. Erythematous papular scaly skin diseases Common psoriasis, simple furfura, pityriasis rosea, lichen planus, erythroderma. 10. Connective tissue diseases Common lupus erythematosus, scleroderma, dry syndrome and dermatomyositis. 11. Herpetic dermatosis Commonly known as herpes zoster, herpes pemphigoid. 12. Pigment disordered skin diseases The common ones are melasma, vitiligo, tattoo, freckle, pigmented nevus, coffee spot, chloasma, freckle-like nevus, Riehl’s melanosis, perioral nevus, nevus of Ota, pigmented nevus of the hairy epidermis, generalized nevus of black, follicular nevus of facial – neck hair, pigmented pityriasis rosea, nevus of mottled spots, congenital nevus of pigmented nevus, folded part. Reticular pigmentation anomalies, Mongolian spots, tattoos, vitiligo, non-pigmented nevus, centrifugal acquired leukoplakia, hereditary symmetrical pigmentation anomalies, anemia nevus, etc. 13. Diseases of skin appendages Commonly include acne, rosacea, seborrheic dermatitis, pemphigus, alopecia, hyperhidrosis and hyperhidrosis. 14. Hereditary skin diseases The common ones are ichthyosis, keratosis pilaris, lichen planus, hereditary herpetic epidermolysis bullosa, familial benign chronic aspergillosis. 15. Nutritional and metabolic disorders of skin diseases Common vitamin deficiencies (toad skin disease, riboflavin deficiency disease, niacin deficiency), enteropathic acrodermatitis, xanthomatosis. 16. Skin tumors: pre-cancerous skin diseases, such as solar keratosis, mucous membrane leukoplakia; malignant skin tumors, such as Bowen’s disease (carcinoma in situ), eczema-like carcinoma (Paget’s disease), basal cell carcinoma, squamous cell carcinoma, mycosis fungoides granulomatosis, malignant melanoma. Etiology As the first line of physiological defense and the largest organ of the human body, the skin is always involved in the functional activities of the organism and maintains the unity of the organism and the natural environment, and abnormalities of the organism can also be reflected on the surface of the skin. The skin has nearly perfect physiological protection functions, such as barrier function, sensory function, regulation of body temperature, absorption, secretion and excretion, etc., in maintaining the health of the body, plays a very important role. Impairment of the physiological functions of the skin causes skin diseases. Skin diseases in the most common causative factors are infectious diseases and allergic dermatitis, but with the degenerative changes of aging, senile skin disease, skin cancer, etc. is also an important skin disease, in addition to the need to pay attention to various skin disorders due to the side effects of drug therapy diseases. Specifically summarized in the following categories: 1. Physical and chemical factors Pressure and friction, local temperature changes too quickly, radiation, light, thermal radiation, chemical reagents and other factors can cause dermatosis. Some factors can aggravate the skin disease. Such as excessive scratching secondary infection; hot water scalding, soap and water washing, improper use of medication to aggravate eczema lesions; exposure to the sun can aggravate photosensitive diseases. 2. biological factors insect bites, contact with certain plants, parasites and microbial infections are common pathogenic factors, such as viral infections caused by a variety of viral skin diseases. 3. Food and other diseases Some foods such as shrimp can easily cause allergic diseases. Visceral lesions, local infections, blood and lymphatic circulation disorders can cause related skin diseases, such as diabetic patients prone to pruritus, local infections caused by infectious eczema-like dermatitis, circulatory disorders can lead to cyanosis, acrocyanosis, and so on. 4. Heredity Some diseases have obvious family history, such as ichthyosis, albinism and so on. 5. Neuropsychiatric factors Nerve damage can cause trophic ulcers; stress and tension and pemphigus, chronic lichen simplex, etc. closely related. 6. Metabolic and endocrine factors Metabolic disorders can cause skin amyloidosis, xanthoma, Cushing′s syndrome is prone to acne, hairy. Treatment The most widely used treatment for skin diseases is topical medication. If the choice or use of topical drugs is not appropriate, often ineffective, or even make the condition worse. Dermatologic topical drug selection should pay attention to the following aspects: the same drug has different dosage forms, such as solution, burnt, powder, cream, lotion, ointment, tincture and emulsion. Different dosage forms have different effects and indications, so according to the clinical symptoms and lesion characteristics of different stages of the disease, the correct choice of different dosage forms of topical drugs. 1. In general, when the local redness, swelling, blisters and vesicles are in the acute stage, the solution is often used to apply wet compresses, which can play the role of anti-inflammatory and heat dissipation; for those who have oozing fluid, the solution is used to apply wet compresses first, and the oil is used later. 2. When the lesions are in the subacute stage, the redness and swelling are reduced, the exudate is reduced, and char, powder and lotion can be used as appropriate to play the role of anti-inflammatory, antipruritic, astringent, protective effect. 3. When the lesions are thickened in the chronic stage and show mossy changes, creams, ointments and ointments can be used. 4. The time and frequency of medication for skin diseases should also be noted. Medicine and lotion, easy to volatilize and reduce the efficacy, the number of medication is relatively more, generally every 3 hours to apply 1 time; tincture, ointment effect is durable, every morning and evening with 1 time can be. Wet compress method should also be appropriate. Before using the medicine, in addition to cleaning the affected area, for the scab, should be disinfected and softened with food oil and then wiped away. If you see blisters larger than half a centimeter in diameter at the skin lesions, you should use a sterilized empty syringe to extract the contents and retain the walls of the blisters. There are hairy parts of the drug before, should first shave the hair, and then on the drug. 5. The selection of drugs should also take into account the age, gender, location and physical condition of the patient. Such as the old and young patients should choose low concentration of drugs; pregnant women using topical drugs, should take into account the impact on the fetus, breast; face, breast, vulva can not be used in high concentration or irritating drugs, children, women should be used with caution; palms of the hands, the soles of the feet, etc. can be used in high concentration of drugs; skin sensitivity, the first use of low concentration, and then use a high concentration. For new drugs or easily sensitized drugs, the first small area with, such as no reaction, and then according to the need to gradually increase the concentration and expand the use of area. Physical therapy is also a common treatment for skin diseases. Commonly used physical therapy: electrotherapy, light therapy, microwave therapy, cryotherapy, laser, hydrotherapy, radiation therapy. Skin is the most fragile cell of the human body, so we usually must pay attention to hygiene, for example: living supplies can not be common, they should have their own living supplies, go out to wear a mask, do not contact with small animals too closely, go to test their own allergies have no allergic items, to avoid allergic conditions. Increase their own immunity, do not belittle the power of skin disease oh.