The black circle around the anus is usually caused by normal pigmentation, incomplete cleaning of the perianal skin and other non-disease factors, and is a common phenomenon, so pay attention to the daily cleaning of the perianal skin. In addition, physical and chemical factors, disease factors can also cause this phenomenon. A, physiological factors: 1, skin pigmentation: the skin itself is darker patients, if the anal skin is dark is a normal situation. And with age, sexual life and other influences, the level of sex hormones in the body, can also cause pigmentation of the skin around the anus, thus showing the appearance of black. In addition, the local skin of the anus due to defecation stimulation, intimate clothing material is poor, such as long-term friction, will also form pigmentation, this situation is a normal physiological phenomenon, without additional treatment; 2, anal unclean: anal local skin cleaning is not in place, resulting in the accumulation of stains, can also cause the skin around the anus appears a circle of black. After each bowel movement and before going to bed, the anus should be properly cleaned, which can alleviate the phenomenon of a circle of black anus. Second, physical and chemical factors: some physical and chemical factors, such as the use of physical rays for perianal skin irradiation treatment, or the use of potassium permanganate and other strong oxidants for sitz bath treatment, can also cause a circle of black skin around the anus performance, generally after the cessation of the relevant physical and chemical treatment, such symptoms will also be improved. The actual hemorrhoids are generally associated with obstructed venous reflux around the anus, which can cause a circle of black around the anus, and the patient will also be accompanied by anal pain, itching, defecation difficulties, blood in the stool and other uncomfortable symptoms. If the skin involved is small, you can use nitroglycerin ointment, hemorrhoid cream and other topical drugs to relieve, but if it has seriously affected the local blood flow, you can also take surgery to remove; 2, anal eczema: anal eczema can cause skin pigmentation around the anus, manifested as black, in addition to obvious itching, blisters, redness and other changes. The black color caused by anal eczema can be relieved by applying tacrolimus cream, glucocorticoid cream, etc.; 3. pigmented nevus: pigmented nevus is a black mole around the anus, which usually does not cause uncomfortable symptoms and does not affect human health and generally does not need to be treated, but if the mole is enlarged and deformed, it needs to be promptly treated and surgically removed if necessary; 4. melanoma: anal melanoma grows rapidly and They can be cured by complete surgical removal and radiotherapy.