Acne vulgaris is a chronic inflammatory skin disease of the sebaceous glands with a prevalence of 70% to 87%, and it affects adolescents disproportionately. It occurs mainly on the sebaceous areas of the face and chest and back, and is often accompanied by seborrhea. It mostly heals or decreases after puberty. The main factors include increased sebum production, hyperkeratosis of the epithelium at the mouth of the hair follicle and the proliferation of Propionibacterium acnes in the hair follicle, and there is also a relationship with genetic factors. The basic lesion is acne, also known as acne vulgaris. Closed acne is a small pale white nodule that becomes a white-headed acne with occasional redness around it; open acne is a black-headed acne with black congestion in the dilated follicular pores. Clinical manifestations Acne begins to appear in adolescence, although in adolescence there can be significant whiteheads and blackheads acne, but inflammation is often light, only small papules and pustules, when older, the affected area is oily, in addition to acne, there are often papules, nodules, pustules, abscesses, scarring and scar sore damage, often one of the lesions more prominent. The lesions occur mainly on the oily face, but can also appear on the upper chest, back, and even buttocks, ranging from pimples and papules in mild cases to large abscesses in severe cases. The course of the disease can last for many years, often sometimes alleviating, sometimes aggravating to gradually reduce in middle age, usually after 40-50 years of age healed, more or less left atrophic scar, but also have scarring damage. Patients generally have no conscious symptoms, and may have pain and tenderness when the inflammation is intense. There are various names for acne according to the nature of the major lesions: 1. Pitting acne: Blackheads are the main lesions of acne, which are cheese-like semi-solids stuffed in the mouth of a sebaceous gland and exposed outside the mouth of the hair follicle. 2.Papular acne: When acne is inflamed, it can become a small rice to pea-sized hard papule, light red to dark red. There may be a blackheaded pimple in the center of the papule or a sebaceous plug at the tip that has not turned black. 3, Pustular acne: Acne becomes pustules due to secondary infection, which can be as large as a pea or larger, often at the top of the papule, which breaks down and releases sticky pus, sometimes with deeper pustules. 4. Sclerosing acne: When the inflamed area is deeper, pustular acne can develop into thick-walled nodules of varying sizes that are light red or purplish-red. Some of them are buried deeper, while others are significantly elevated and become hemispherical or conical in shape, which exist for a long time or are gradually absorbed. 5. Atrophic acne: The damage to the papules or pustules causes pit-like atrophic scarring, and fibrous degeneration and atrophy are caused by ulcerated pustules or naturally absorbed papules and pustules. 6, cystic acne: In addition to the above types, deep inflammation can also be called giant abscesses, some containing larger blackheads pimples, these cystic abscesses often contain blood-tinged jelly-like pus, while inflammation is often not heavy, later can occur obvious scarring, sometimes become keloid. Papular or pustular damage can also cause scarring lesions. 7, skin scratching acne: occurs in nervous young people, especially young women who love beauty and pay attention to cleanliness, especially care for the tiny facial acne often in front of the mirror squeeze scratching and cause skin scratching, blood scabs or scar formation. Some frequent squeezing and scratching in the pre-menstrual period, and acne is reduced only after the menstrual period or menstruation. This kind of pre-menstrual acne often appears in adult women, and is often related to mental tension. 8. Convergent acne: This is the most serious type of acne, including acne, papules, pustules, abscesses, cysts and fistulas that break down and flow pus. In some patients, lesions occur on the lower back, buttocks and femur.