A lump at the root of the ear may be related to enlarged lymph nodes, sebaceous cysts, folliculitis, lipoma and so on. 1. Enlarged lymph nodes: There are lymph nodes behind the ear at the root of the ear, and the inflammatory reaction of the lymph nodes leads to an increase in the size of the lymph nodes, accompanied by redness, swelling, pressure and pain in the form of lumps, resulting in a pimple at the root of the ear, which may be accompanied by hearing loss, parotid gland enlargement, sore throat and other symptoms. 2. Sebaceous cysts: Sebaceous glands at the root of the back of the ear secrete exuberantly, resulting in sebaceous gland ducts blocked, appearing as cysts with smooth surfaces and clear boundaries, resulting in a pimple at the back of the ear. 3. Folliculitis: Bacterial infection leads to inflammatory reaction of hair follicles, resulting in red papules, accompanied by itching, pain and other symptoms, resulting in a pimple at the back of the ear. 4. Lipoma: abnormal proliferation of fat cells, the formation of benign soft tissue tumors, lumps under the skin, usually no obvious symptoms, resulting in a lump behind the ear. There are many reasons why a lump grows behind the ear, so it is recommended to go to the hospital in time for examination, to clarify the cause of the disease, and actively treat it, so as to avoid affecting the health of the ear.