If a patient has a painful bag behind the ear, the following aspects are mainly considered: the first one is a congenital fistula behind the ear, often related to genetic factors, which can be very painful if infected and often requires surgery to resolve. The second is a sebaceous cyst behind the ear, which often occurs in young people because the metabolism is more vigorous and sometimes the sebaceous gland is blocked and the sebaceous cyst becomes infected, so it is recommended that active anti-inflammatory measures be taken to reduce the swelling. Thirdly, the swelling of the lymph nodes behind the ear is usually caused by inflammation in the middle ear cavity. It is recommended that the patient be treated with symptomatic anti-inflammatory and anti-swelling treatment after the CT of the middle ear is completed.