A hard lump protruding from the anus and caudal groove may be perianal abscess, external hemorrhoids, etc.; if the lump is near the caudal groove, it may be sebaceous cyst, etc. 1. Perianal abscess: Due to the infection in the rectal-anal tube tissue or its surrounding interstitial space, it can lead to inflammation, redness, swelling, hard lumps and other symptoms of the skin around the anus. If the abscess is small, oral antibiotics, topical anti-infection ointment, etc., and those who have difficulty in defecation can take oral laxatives to soften the stool. If the abscess is large, it needs to be incised and drained as soon as possible to avoid further spreading of the infection. 2. External hemorrhoids: usually due to prolonged standing, abdominal pressure and other factors lead to pathological expansion of the subcutaneous venous plexus on the distal side of the dentate line or connective tissue hyperplasia, which in turn makes the anus appear hard pimples. If the patient has blood in the stool, pain and other symptoms, should go to the hospital in time to receive professional treatment. 3. Sebaceous cysts: If the sebum secreted by the sebaceous glands in the perianal area can not be discharged normally in the mouth of the hair follicles and form accumulation, cysts may be formed in the area. When the cyst is large, it will be seen on the surface of the skin as a rounded bulge and feel hard when touched by hand. The most common cure is surgical excision under local anesthesia, with antibiotics to fight infection. If you have a hard lump in the anus, you need to go to the hospital for examination, make a clear diagnosis, and receive professional treatment as soon as possible to avoid further development and aggravation of the hard lump.