After the swelling of the buttocks has subsided, there has been a small spot, may be sebaceous cysts, boils and other causes, need to be further differential diagnosis by a doctor. 1. Sebaceous cysts: sebum secreted by sebaceous glands is not normally discharged and accumulates under the skin to form localized cysts, which are often of different sizes, with small cysts only the size of a grain of rice. After the sebaceous cyst infection subsides, there may be a small opening on the skin surface. 2. Boils: If a single hair follicle is infected by pathogenic bacteria such as Staphylococcus aureus, boils may appear, ranging in size. After the pus drains from the buttock boil and the inflammation subsides, a small spot can also remain on the surface of the skin for a short period of time, which can subside after a few days. It is recommended that the person who has a small spot on the buttocks after the swelling subsides should go to the regular hospital in time if he or she experiences any discomfort, to clarify the cause of the disease and to carry out standardized treatment under the guidance of the doctor, so as not to bring adverse effects to the body due to the delayed condition.