There is a hard lump on one side of perianal area which is not painful when pressed, and it is considered to be related to anal fissure, lipoma, perianal cancer and other diseases. 1. Anal fissure: anal fissure occurs in the middle of the posterior region, and oval ulcers can appear at the anal verge, while old anal fissure is grayish-white in color, often with anterior hemorrhoids, which can be manifested as the phenomenon of no pain when pressed. 2. Lipoma: it is a mass formed by the proliferation of subcutaneous fat, with soft texture, obvious boundary and good mobility, usually without pain and discomfort. If the lipoma grows too fast and painful, it needs to be removed through surgery. 3. Perianal cancer: In the early stage of perianal cancer, it manifests as a slow-growing hard nodular lump, accompanied by itching symptoms. When the lump increases in size, ulcer and erosion can be formed. If there is a hard lump on one side of perianal area which is not painful when pressed, it is recommended to go to the hospital in time to clarify the cause of the disease and give treatment to avoid delaying the aggravation of the disease.