The cause of a lump in the jaw may be enlarged lymph nodes, folliculitis, sebaceous cysts, etc. 1. Enlarged lymph nodes. It is a common cause of lumps in the jaw, the causes of lymph node swelling in the jaw include inflammation of the root of the teeth in the jaw, inflammation of the tonsils, colds, chronic pharyngitis, inflammation of the wisdom teeth, etc., and if it does not subside for a long time, you should seek medical treatment in a timely manner. 2. Folliculitis. Folliculitis is a purulent inflammation of the entire hair follicle produced by bacterial infection, which can evolve from red papules to papular pustules, and there will be mild pain. 3. Sebaceous cysts, sebaceous cysts may form when the sebaceous glands produce a lot of fat and clog the pores.