A hard lump on the back of the neck pain is common for the following reasons: first, folliculitis, generally do not worry too much, can be applied locally iodophor, pepto-bismol and other topical medications, you can also use iodine to disinfect, and then alcohol deiodination, generally about a week of time the swelling and pain can gradually disappear. Second, sebaceous cyst infection, this is due to follicle obstruction caused by the disease, need to go to the hospital for physical examination and neck ultrasound to make clear, if the disease, need to be under anesthesia to carry out the excision of the swelling, if a long time to not deal with may lead to further aggravation of the swelling and pain, and even the local will be broken, pus, leading to the formation of scarring. Third, the pain caused by lymph node hyperplasia, which needs to further check the blood routine and so on for clarification, and if necessary, need to carry out puncture biopsy of lymph nodes or excision of lymph node biopsy, in order to clarify the nature of its. In conclusion, if there is persistent pain in the swelling, it is necessary to go to the hospital in time in order to clarify the cause of the disease.