If you feel a hard lump the size of a soybean under the skin of the perianal area, you need to consider that it is related to thrombosed external hemorrhoids, sebaceous cysts, condyloma acuminatum, perianal abscesses, and anal fistulas. 1. thrombosed external hemorrhoids: that is, the area of the capillary rupture bleeding, blood is not discharged smoothly, coagulation in the skin below. Patients will experience more severe pain, the color of the thrombosed external hemorrhoids is usually purplish-red, and may also be accompanied by bleeding during bowel movements. 2. Sebaceous cysts: If the sebaceous glands in the area are blocked, sebum will gather under the skin and form small bumps. 3. Condyloma acuminatum: This is caused by HPV virus infection. In the early stage of the disease, there may be soybean-like or papillary bumps, grayish-white in color, with a foul smell. 4. Perianal abscess: once the formation of perianal abscess, the patient may have purulent secretions around the anus or subcutaneous, gathered together to form small hard lumps, accompanied by obvious pain. 5. Anal fistula: If the perianal abscess is not treated in time, it may develop to the subcutaneous, forming a small hard lump, with pressure pain, may also be accompanied by redness, swelling and pain phenomenon. With the development of the disease, there may be ulceration and bad odor. When a hard lump of soybean size is felt under the skin of the perianal area, considering the complexity of the etiology, it is recommended that the patient seek medical treatment in time for a systematic examination and differential diagnosis.