Hard lumps on the body may be keloids, folliculitis, epidermal cysts or syphilis and other diseases. Keloids are caused by abnormal proliferation of connective tissue. Many patients are genetically predisposed to keloid scarring, and are prone to localized formation of hard, hardened growths protruding from the skin surface after burns, scratches, or surgical procedures. Folliculitis is caused by pathogens such as bacteria or fungi, and is usually caused by small breaks in the skin that are invaded by pathogens. It is prone to occur in people who do not observe hygiene, are immunocompromised or are diabetic. Epidermal cysts are benign skin tumors that may be caused by congenital developmental abnormalities or by trauma and other causes such as implantation of epidermal tissue. The initial manifestation of syphilis is a hard chancre, which may appear as a cartilaginous, hard, painless ulcer on the vulva. Syphilis is a sexually transmitted disease (STD) that is mainly transmitted sexually, through blood or from mother to child. Young people who are sexually active, etc. are susceptible to syphilis. In addition, the appearance of hard lumps on the body may also be the appearance of skin tumors, such as squamous cell carcinoma, basal cell carcinoma or melanoma. These cancers are associated with long-term ultraviolet radiation exposure, inflammatory stimuli, and the use of immunosuppressive drugs. The incidence rate is relatively high in people with family history or long-term sun exposure. It is recommended that patients with hard lumps go to regular hospitals in time for a clear diagnosis and standardized treatment under the guidance of doctors.