Nodular bumps on the skin can be caused by bacterial infections, as well as lipomas, epidermoid cysts, and keloids. 1. Bacterial infection: The skin is damaged by a small injury, bacterial infection, causing folliculitis, boils, resulting in nodular skin elevation. Bacterial infection leads to localized lymph node enlargement, resulting in localized skin nodules, which can also be accompanied by pain. 2. Lipoma: the cause of lipoma is still unclear, and it is currently believed to be related to heredity. Lipoma grows slowly and is easy to be neglected. Tumors gradually increase in size, resulting in the appearance of local elevated swelling. 3. Epidermoid cysts: Epidermoid cysts are associated with epidermal implants, skin infections, acne and other factors. Epidermoid cysts can occur anywhere on the body, resulting in raised nodules on the body surface. 4. Keloid: It is a pathologic scar with abnormal proliferation of connective tissue in the skin, mostly secondary to skin trauma or spontaneous formation. The main clinical manifestation is round or irregular smooth, solid nodules, occasionally itchy and painful. The appearance of palpable nodules on the skin, accompanied by swelling and pain, may also be other causes, you can go to the hospital dermatology, general surgery and other medical treatment, please ask the doctor to deal with.