Anal surgery is a clinical subspecialty of general surgery, and this specialty covers perianal diseases and colorectal diseases. Today I will briefly introduce the common perianal diseases for you. Common perianal diseases: 1, hemorrhoid disease. 2.Anal fistula and fistula perianal disease. 3.Anal fissure. 4, perianal abscess or other perianal infectious diseases. 5, perianal tumors (including benign or malignant). 6.Perianal functional lesions. Hemorrhoids: External hemorrhoids or mixed hemorrhoids often show perianal swelling prolapse after defecation, which can be returned by itself or not after defecation, dripping blood after defecation, bright red, blood-stained hand paper, with or without painful defecation. Internal hemorrhoids often present with blood in the stool, blood dripping after defecation, blood-stained toilet paper, and separation of blood and stool. Anal fistula: It is often secondary to a perianal abscess or post-infection recovery period, and in the early stage, it usually presents as a gradually increasing perianal mass with pain, and then after treatment or self-rupture into a long-lasting sinus tract. In long-term patients, the subcutaneous sinus tracts may be palpable and point in the direction of the anus. Anal fissures: often secondary to chronic constipation or diarrhea with a high frequency in a short period of time, dry stool or repeated diarrhea leads to tissue damage in the anal canal area, resulting in fresh anal fissures, which, if not properly treated, become chronic. In severe cases, this can lead to fear of defecation, which can increase the degree of dryness of the stool and make defecation more difficult, forming a vicious circle. Perianal abscess: The common manifestation is the gradual increase of the perianal mass with pain, and the superficial abscess is often accompanied by local redness, swelling, heat and pain, and the patient is unable to sit and stand normally, unable to walk normally, and some patients have increased body temperature and other signs of infection. Perianal tumors: benign can be seen as tuberculosis, acromegaly, hyperplasia, inflammation and other masses, which can be diagnosed through pathological examination. Malignant tumors may include squamous carcinoma of the anal canal, malignant melanoma, junctional tumors and other tumors of skin origin.