Hi, and thanks for your medical question on eHealth forum!
The various possibilities are a cyst, a neurofibroma (localized harmless swelling in a nerve), lipoma (localized collection of fat), a swollen lymph node, a tubercular abscess, or an acne. Rarely is it a bony tumor like osteoma. I think you should discuss these possibilities with your doctor.
Watch the lump. Do not touch everyday but once in 10-15 days. If the lump increases in size, becomes painful, changes color, bleeds, changes shape or consistency or more similar lumps appear then immediately consult a doctor. Otherwise seek a regular appointment and get this investigated. Usually such lumps do not need treatment, unless for cosmetic purpose, and unless it is a tubercular lump. Hope this helps. Take care!