A soft bump behind the ear that is not painful or itchy is usually a sebaceous cyst. Sebaceous cysts are very common and are superficial swellings that occur on the head, face, back, etc. They are caused by obstruction of the sebaceous glands and can appear as a mass, which is usually painless and does not itch, protruding from the surface skin, often with a black spot in the center. This disease is easily complicated by infection, and once infection occurs, there will be local redness and swelling, which will be painful at this time, and in severe cases, abscesses will appear, and fluctuating sensations can be palpated. When a sebaceous cyst develops behind the ear, surgical removal can be considered to prevent the mass from increasing in size and to prevent it from becoming infected. The surgery is relatively simple and can be performed under local anesthesia to completely cure the disease.