A hard bump on the chin may be related to boils, sebaceous cysts, acne and other causes. 1. Boils: Acute purulent diseases caused by pathogenic bacteria such as Staphylococcus aureus invading hair follicles and their surrounding tissues, which can cause local redness, swelling and pain. 2. Sebaceous cysts: If the sebaceous gland secretions are blocked and form cysts under the skin, they may appear as hard bags. 3. Acne: Acne is caused by abnormal hormone levels, exuberant secretion of sebaceous glands and proliferation of Propionibacterium acnes, which can manifest as skin nodules and cysts. It is recommended that people with a hard bag on the chin go to the hospital in time to clarify the cause of the disease and carry out standardized treatment under the guidance of the doctor, so as not to delay the disease and bring adverse effects on the body.