Lump behind the ear root should be alert to lymph node enlargement, sebaceous cyst, folliculitis, lipoma and other diseases. 1. Enlarged lymph nodes: Inflammation occurs in the nearby tissues, such as acute pharyngitis, acute tonsillitis, etc. As the inflammation spreads to the lymph nodes behind the ear causing enlargement, so there is a lump at touch, accompanied by pain. 2. Sebaceous cysts: the sebaceous gland ducts at the base of the ear are clogged with exuberant secretion, forming cysts, so there are lumps when touched, most of which do not cause pain. 3. Folliculitis: the hair follicles at the base of the ear become infected and cause inflammation, forming lumps with pain. 4. Lipoma: excessive accumulation of subcutaneous fat cells behind the ear root forms a lump, which is hard to touch and can be moved. If there is a lump behind the ear root, there may be other diseases, it is recommended to consult a doctor in time to find out the cause of the disease and treat it as soon as possible.