Hard bumps on the body may be benign masses, such as sebaceous cysts or epidermoid cysts, or they may be enlarged lymph nodes, or they may be malignant tumors. In the case of sebaceous cysts or epidermoid cysts, the mass is usually hard and subcutaneous, with clear borders, and may or may not be painful on pressure. Sebaceous cysts are small black dots on the surface, which are openings for sebaceous glands. Epidermoid cysts do not have black dots on the surface, and the contents of both are like bean curd-like. If there is a secondary infection, redness and swelling can occur, and even abscess formation, which usually requires surgical removal after the diagnosis is clear. It may also be caused by swollen lymph nodes, mostly seen when the lymph nodes are inflamed, and also seen when the tumor metastasizes, that is, when lymph node metastasis occurs, the lymph nodes need to be removed and sent for pathological examination. If the mass is formed by malignant tumor, it usually includes hard texture and unclear boundary, and when the diagnosis is clear, the mass needs to be completely removed and sent for pathological examination.