The main causes of this situation include the following: 1. caused by skin lesions around the anus, such as perianal eczema, mainly related to the abnormal secretion of anal glands, conditions that may cause abnormal secretion of glands may cause this reaction. For example, severe prolapse of the rectal mucosa more serious internal hemorrhoids, benign tumors of the rectum, polyps, malignant tumors of the rectum such as rectal cancer, inflammatory reactions of the perianal mucosa. 2, may be related to perianal abscesses, more serious thrombosed external hemorrhoids, both of which may cause the skin around the anus to react, and if accompanied by mild inflammation will produce itching and pain. 3, localized anal itself Lesions such as anal sinusitis are due to blockage of the glandular ducts around the anus, causing an inflammatory reaction in the glands themselves.