A hard lump on the side of the anus is mainly considered to be related to pathological factors such as perianal abscess, hemorrhoids, tumors and so on. 1. Perianal abscess: such as sedentary, diarrhea, eating spicy and stimulating food can cause anal gland infection, the infection can spread to the perianal area along the rectum, the anal canal, causing perianal abscess appear hard lumps, can be accompanied by pain. 2. Hemorrhoids: such as mixed hemorrhoids by long-term sedentary, alcohol, spicy diet and other dietary stimuli may cause hemorrhoidal nuclei swelling, stasis, hemorrhoidal vein bruising leading to thrombosis, can be manifested as perianal lumps. 3. Tumor: such as anal canal cancer can cause hard mass in perianal area, and the surface can be cauliflower-like. Therefore, if there is a hard lump on the anus, it is recommended to go to the hospital in time to find out the nature and cause of the hard lump, and actively treat the cause to avoid delaying the condition.