A hard bump on the head that doesn’t hurt or itch may be a sebaceous nevus, sebaceous cyst, dermatofibroma and other diseases. 1. Sebaceous nevus: This disease may be related to the abnormal development of sebaceous glands, or it may be related to gene mutation. Usually during adolescence, a light brown or brown papilloma-like elevation appears on the scalp without hair on it. They are usually removed by cryotherapy and surgery. 2. Sebaceous cysts: The disease is caused by the blockage of sebaceous gland ducts, so that sebum gradually accumulates and forms cysts, which are commonly found on the head, face and back. Sebaceous cysts are usually asymptomatic and appear as hard, painless bags on the head. They are usually treated by surgical excision. 3. Dermatofibroma: the etiology of dermatofibroma is not yet clear, mainly formed by fibroblasts or histiocytes proliferation, hard texture, generally limited. Surgery can be chosen for treatment, but the disease is prone to recurrence. A hard bag on the head without pain or itching may also be caused by other diseases, it is recommended that the patient go to the hospital in time, after a clear diagnosis under the guidance of the doctor standardized treatment.