A hard lump on the chest may be the patient suffering from sternum fracture, skin tumor, skin allergy, breast disease and other diseases. 1. Sternum fracture protrusion: a hard lump on the chest may be a sternum fracture and protrude from the skin surface, if the chest has suffered violent injuries before, there is a greater possibility of a hard lump on the chest phenomenon, the need for patients to go to the hospital to prevent dislocation. 2. Skin tumors: sebaceous cysts, lipomas, etc., generally benign lesions. Sebaceous cysts protrude on the surface of the skin, the most obvious in the neck and chest back, accompanied by pain and pus when infected; lipoma is generally smoother, clear boundaries, protruding from the surface of the skin, and can be pushed. 3. Skin allergy: certain allergic substances can lead to skin pimples, pimples are a primary skin lesion of dermatological diseases, the skin surface is elevated, the diameter of the size of one centimeter or so, the color is usually black-brown and yellowish, and it is easy to form a protruding hard lump after long-term wear and tear. 4. Breast diseases: such as breast hyperplasia, breast fibroadenoma, breast cancer, etc., will also appear on the chest (on the breast) hard lumps, found that should be timely consultation, clear cause of treatment. There is a hard lump on the chest, patients are advised to go to the hospital for examination and treatment in time to control the condition.